Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Working Vessels => Topic started by: 1967Brutus on December 13, 2023, 08:40:25 am
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Since most likely in this section there is the most experience with propulsion systems on tugboats, I'd like to ask you guys:
For a 105 mm diameter fourbladed prop in a tugboat, what would be the expected thrust at a given amount of power, and what kind of RPM would I be looking at? Does anybody know if there is this kind of info availlable in for example tables or online propcalculators or such?
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You have listed the diameter of the prop, but other factors need consideration. 1) the shape of the prop, 2) the pitch of the prop, the operating rpm of the prop. I'm not a naval engineer so there are probably more factors involved. %)
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That's the thing: I actually AM a naval engineer, and I do know what factors are in play, but...
I cannot give a pitch, because it is a controllable pitch propeller (4 blades), and I do not know an RPM, I only know that I most likely have 80 Watt availlable at somewhere between 1000 and 1500 RPM.
So I need "general propeller data" to be able to make an estimate on the eventual reduction ratio, IF needed...
If anything else fails, I would be interested in for example, people that use a 4 bladed 105-ish mm prop and ever have measured, to hear their ree running and moored shaft RPM and Watts (Volt x Amps)
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I think you could be better off by reversing the matter and using old propellor design formulae which seem to be simpler.
You'll have to choose a series of discrete pitches covering the range you're working in and you should get a graph.
Good luck anyway :-))
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I think you could be better off by reversing the matter and using old propellor design formulae which seem to be simpler.
You'll have to choose a series of discrete pitches covering the range you're working in and you should get a graph.
Good luck anyway :-))
That is exactly what I intend to do, because I am aware that a controllable pitch propeller does not have a fixed set of parameters... IF ONLY... If only I could find propellerdata, and I seem not to be able to find that.
All I see is propcalculators that are laid out to find a prop for a boat and installed power, but I want it the other way around: I want to find a power and RPM for a given prop. The imput fields of those prop calculators however do not allow the search the way I want it. So I am a bit depending on those of you that have measurements done on their props, so I can collect data and construct a graph.
I have contacted the original manufacturer, Raboesch, which still exists and even is located in my home country, but I have not yet heard back (sent my question Sunday evening).
I am at sea right now, but if I haven't heard from them by the time I get home, I'll either call them or even visit them (they are about 100 km away from me).
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Selecting scale model boat props has always been a black art depending more on empirical comparisons than theoretical data.
In your case not many conventional model boats employ props of that diameter and the number of those using controllable pitch must be negligible so you are extremely unlikely to find any convenient tabular data.
You might be better off setting up a test rig in a tank and measuring the various inputs and outputs as best you can at varying pitch settings on the prop. Power consumption can be readily measured using a wattmeter but output thrust would be more difficult and might need to be assessed by eye.
Colin
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Selecting scale model boat props has always been a black art depending more on empirical comparisons than theoretical data.
In your case not many conventional model boats employ props of that diameter and the number of those using controllable pitch must be negligible so you are extremely unlikely to find any convenient tabular data.
You might be better off setting up a test rig in a tank and measuring the various inputs and outputs as best you can at varying pitch settings on the prop. Power consumption can be readily measured using a wattmeter but output thrust would be more difficult and might need to be assessed by eye.
Colin
That would require me to build a fairly large test tank, and buy a large electric motor and measuring equipment. I know large boats are relatively rare, but I was hoping that, since people building large boats tend to be a bit more finicky, might have measured their amps and RPMs.
I am an engineer, and I have some empirical data on a 50 mm controllable prop, but from 50 to 100 mm is a bit too large of an extrapolation to be really reliable.
Oh well, it was worth a shot...
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What I was thinking of when I suggested reversing the situation was using a simple flat-bladed prop as an example, with a 1:1 pitch, calculating the possible thrust, allowing for a guestimate of the slip, from the 80 watts you think. If you repeat, changing the pitch in increments, you should get a graph which would give an indication. Also, a decent prop should be more efficient so the graph should understate.
Better than doing a Computational Fluid Dynamics degree anyhow. %)
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What I was thinking of when I suggested reversing the situation was using a simple flat-bladed prop as an example, with a 1:1 pitch, calculating the possible thrust, allowing for a guestimate of the slip, from the 80 watts you think. If you repeat, changing the pitch in increments, you should get a graph which would give an indication. Also, a decent prop should be more efficient so the graph should understate.
Better than doing a Computational Fluid Dynamics degree anyhow. %)
I know what you mean.
The thing is: For aero propellers, calculators that return a thrust and absorbed power, for an imput of propsize and RPM, are in abundance.
I cannot find that for ships propellers.
Mind you, I may not be expressing myself properly, English is not my first language.
If you have such a calculator that calculates the thrust and RPM for a given imput and propsize, I would be much obliged.
I can reverse that by messing with the numbers to create the graph. But the calculators I find, do not work very convenient for that purpose.
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I know large boats are relatively rare, but I was hoping that, since people building large boats tend to be a bit more finicky, might have measured their amps and RPMs.
Many large model boats are warships which, like their full size counterparts, use multiple screws. A 100mm prop is huge by comparison; there are very few single screw boats with this size and most are tugs as you know. (of these steam is often the favoured power plant as it offers lower rpm combined with high torque.)
Matching motors to props at model sizes is a question that often comes up but there is not much in the way of published data and in most cases the empirical route is taken whereby you try to identify a similar model which works satisfactorily and extrapolate from that. Back in 2021 I contributed an article in Model Boats magazine which was intended to help modellers in selecting motors and props by publishing the details and characteristics of a number of typical scale model boats which could be used as rough benchmarks for comparison purposes. It was practical rather than scientific as I am no engineer. If you PM me your email address I can send you a copy but the largest propellor size mentioned is 70mm.
There are large plastic plant troughs that could be used as a test tank and don't cost much. You mention a large electric motor but surely with a prop of that size you will be using some form of gearing to bridge the gap between motor RPM and prop rpm to maximise efficiency and reduce current drain?
Tony's suggestion could give you a rough estimate of the thrust.
It would be certainly interesting to hear from any forum members who run large single screw boats.
Colin
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Many large model boats are warships which, like their full size counterparts, use multiple screws. A 100mm prop is huge by comparison; there are very few single screw boats with this size and most are tugs as you know. (of these steam is often the favoured power plant as it offers lower rpm combined with high torque.)
Matching motors to props at model sizes is a question that often comes up but there is not much in the way of published data and in most cases the empirical route is taken whereby you try to identify a similar model which works satisfactorily and extrapolate from that. Back in 2021 I contributed an article in Model Boats magazine which was intended to help modellers in selecting motors and props by publishing the details and characteristics of a number of typical scale model boats which could be used as rough benchmarks for comparison purposes. It was practical rather than scientific as I am no engineer. If you PM me your email address I can send you a copy but the largest propellor size mentioned is 70mm.
There are large plastic plant troughs that could be used as a test tank and don't cost much. You mention a large electric motor but surely with a prop of that size you will be using some form of gearing to bridge the gap between motor RPM and prop rpm to maximise efficiency and reduce current drain?
Tony's suggestion could give you a rough estimate of the thrust.
It would be certainly interesting to hear from any forum members who run large single screw boats.
Colin
First bolded: that is what I am trying to collect data for, by asking the question in first post.
second bolded: Will do, and as long as there is enough range in the propellers in that article, I might be able to determine a mathematical relation and extrapolate. I surely appreciate the offer for practical help.
third bolded: There are several ways around that, Direct drive with variable voltage should be not too inefficient and lead to decent calculations, and a geared motor sure also is an option, because in the end, Watts are Watts, and it is rather irrelevant which method is chosen (I am a naval engineer and fairly familiar with all kinds of methods to determine power and efficiency, both electric and IC). I am fairly confident that I can work something out and correct for scale etc etc.
As it is, the drive is going to be a slow-speed single cylinder fourstroke of which I have no data yet, only estimates and goals.
Way I see it, I expect about 80~100 Watt at 1100~1500 RPM, but RPM still has to be selected (sound is the determining factor here) and the actual power to be had, depends on me modifying carb and camshaft (valve timing, these engines are timed for 10K and I need to change that).
I have experience with this kind of drive (thread in the pleasure boat section about Krick Alexandra). I have a 5 cc fourstroke tuned for 1500 RPM. 7 years ago I measured that engine to about 17 Watt and that was enough to drive a Marx 50 mm controllable pitch prop, but just about...
Back then, that was with original valve timing. I recently altered valve timing and by feel, torque (and thus power) doubled but I can't say for sure because it bottomed out my torque measurement set-up. So I would say I am at least able to get 30W from that 5 cc, extrapolating says I should be able to get 80~100 from a 15 cc, give or take.
Now, the situation is, last week I suddenly came into the poisession of this controllable pitch prop, and I have blades for 86 mm or 105 mm.
The idea to go for a 15 cc engine followed the purchase of the prop, not the other way around, so now I am tryingto figure out if the whole idea is viable in the first place.
Just to give an insight in my train of thought here.
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Colin, PM sent. Thanks for the offer.
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Thanks for the additional information, I think we had assumed you would be using an electric motor. A low RPM 4 stroke is of course a different matter. I will send you the article but it may not be of very much use in your circumstances.
Would it be worth looking at advertisements for electric trolling motors (for fishing dinghies etc.)? Some of these have props of around 100mm and there is often thrust and power data quoted for the various motors. You might be able to extract some relevant data.
Colin
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https://the-contact-patch.com/book/fluids/f1518-propeller-thrust (https://the-contact-patch.com/book/fluids/f1518-propeller-thrust)
This looks interesting :-))
Sadly, my son is now in Canada and he's a hydraulics engineer who did his masters on CFD. That said, I'm pretty sure that his answer would be "trial and error" simply because there are so many variables, not the least of which is the prop being in very shallow water.
Another factor in play relates to why the need to know. The prop size and the revs are inter-related anyway so it could be worth looking at some of the steam threads on here where models are used to tow one or two "passengers" along in dinghys. OK, the acceleration is not great but are you planning on towing or just sailing solo?
Also, see if you can find a book by Sidney Barnaby who wrote one of the first guide to prop designs in the 1920's. Worth reading! The copy I had may now be in Nick (raflaunches) reference library.
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Would it be worth looking at advertisements for electric trolling motors (for fishing dinghies etc.)? Some of these have props of around 100mm and there is often thrust and power data quoted for the various motors. You might be able to extract some relevant data.
Colin
Now THAT is a possibly very useful suggestion!
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OK, the acceleration is not great but are you planning on towing or just sailing solo?
I am not really planning anything, I just want to build "a little engine that CAN"... :D :D :D
I don't expect to be towing a lot. It is going to be a large and awkward to handle boat, not something you bring along every sunday, but I just want to be able to "drain the pond and wash all the fish ashore" when I jam the lever to deck.
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%% %% %% :-))
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Thanks for the additional information, I think we had assumed you would be using an electric motor. A low RPM 4 stroke is of course a different matter. I will send you the article but it may not be of very much use in your circumstances.
Would it be worth looking at advertisements for electric trolling motors (for fishing dinghies etc.)? Some of these have props of around 100mm and there is often thrust and power data quoted for the various motors. You might be able to extract some relevant data.
Colin
E-mail received, many thanks again, Colin!
Going to read it tonight, and let the info sink in.
From other sources, I could more or less destill out that per 1W of power (as measured by current, brushed motor, Bühler to be exact but I do not know the type) an approximate of 0,4N of thrust can be generated. Person that shared that with me, said his boat did 10N at 24Watt with normal props in Kort-nozzles, and with props designed for use in tunnels he reached 15N at 36 Watt.
Both measured with tied up boat.
I do not know the diameter, but it is a start that I can theoretically achieve 0,4N per Watt.
That does not yet give me any info on the RPM or the diameter, or the relation between those two.
Some simple idiot-mathematics however would suggest, that maybe tip velocity is a factor, and currently my 50 mm prop runs 1500 RPM, which seems quite OK, therefore for a 100-ish mm prop 750 RPM would be a nice value to start with.
Just going by disk-surface (I would not be surprised if disksurface is a factor) it is for starters not unreasonable to assume, that for same tip velocity, but disk surface quadrupling, absorbed power could be 4 times as high.
Maybe the blade surface/disk surface ratio plays a role in it as well, I need to think about that.
Mind you, this is just some redneck engineering right now, I still need to read those articles you sent me.
But at least I think I start to see some light at the end of the tunnel :D
Will keep you guys updated.
To the moderators: If this thread would be more appropriate in the R&D section, feel free to move it.
EDIT: Oh, and Colin.... :D I don't do "electric"... :p :p :p :p
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EDIT: Oh, and Colin.... :D I don't do "electric"... :p :p :p :p
:-)) :}
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I would tend to think 1500 rpm is about right.
If it was me I would use something like a 550 motor geared down to that speed on 6 volts.
If more speed required up the voltage, if too fast trim the ESC.
Also a Marine Engineer with a few years experience not greatly into indicated power ratings as the wind and waves are not to scale.
Bob
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I would tend to think 1500 rpm is about right.
If it was me I would use something like a 550 motor geared down to that speed on 6 volts.
If more speed required up the voltage, if too fast trim the ESC.
Also a Marine Engineer with a few years experience not greatly into indicated power ratings as the wind and waves are not to scale.
Bob
It is a bit hard for me to copy you guys all in on what I find on other forums, but right now, picking up things left and right, I am inclined to think that this 105 mm prop will absorb somewhere in the neighbourhood of 50~60 Watt at full pitch and 750 RPM
That is in part based on that my current prop (the old Marx 50 mm variable prop) absorbs in the order of magnitude of 12~15W at 1500 RPM and full pitch. Both props appear to have a max blade angle of 45 degrees if I am not mistaken.
Since 750 RPM for the large prop results in by and large the same tip speed as 1500 RPM on the 50 mm prop, and blade angle is the same, but disk surface is 4 times as high, I think power absorption is also 4 times as high.
I think, 1500 RPM is too high, that would make power absorption increase by four, to about 240 Watt.
Mind you, I throw out numbers like it's nothing, but these are ONLY estimations and deductions, I could be wayyy off here. but it is supported by the following: I more or less measured my current prop at roughly 15 Watt at 1500RPM, and according to Marx, the manufacturer, that prop was rated for 500W and 10K RPM.
Now if I go by "double the speed=four times the power" that would be 60W at 3000, 240W at 6000 and if I want to double that, that would be 6000 times root of 2, which is about 8500 RPM. It's not quite there, but close enough to regard "double speed is 4 timesthe power" as to be a reasonable assumption.
am thinking: 1100 RPM should be possible with a direct drive, and the beauty of a variable pitch prop, is that I do not HAVE to have full deflection, now do I? IF, big if, power absorption at 750 RPM would indeed be about 60W, then 1100 RPM (which is pretty close to 750 times root of 2) would be about 120 Watt. 1100 RPM still is low enough to generate a cool tugboat sound...
Since electronics can do amazing things, and I have aquaintances with amazing programming skills, maybe I can have a feedback loop on the engine throttle lever, cutting the pitch back if the throttle passes a pre-set position, preventing the engine to overload. That would result in a control loop that would limit the pitch to full engine load in a bollard pull or towing situation, but release the pitch for a free running boat, and anything inbetween.
Heck, possibly I can even arrange something like that via telemetry feedback and programming in my FrSky Taranis. Who knows?
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I have a small MAP publication titled 'Model boat propellers', which has very good practical advice for matching speeds, calculating thrust etc. Sadly long out of print AFAIK, it was first published in 1972, and revised in 1980.
Books on fullsize propeller design tend to be a little too involved I think.
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Thrust is one factor. Another is the shape and displacement of the hull you are pushing. A lot of variables to get to the end result.
Colin
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Books on fullsize propeller design tend to be a little too involved I think.
Correct... Believe it or not, nautical college does not spend much time on the subject, given that a ship has a propeller and that's that. No one is going to change one iota about that thing, they are in general too expensive.
Several ships that I worked on had fairly extensive data on the installed propeller and I have out of interest tried to wrestle myself through those books, but man, that is tough stuff.
The basics I can understand about the relation to pitch and speed, speed and power, and such, but only on a level as more or less expressed in my previous post, which still basically is "redneck engineering".
But I am slowly getting at least in the ballpark, and things seem to settle in the direction of about 1100 RPM. That should allow the engine to develop decent power, and the prop to absorb that power, give or take. Which is a relief, because it saves me the construction of a reduction gear.
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Thrust is one factor. Another is the shape and displacement of the hull you are pushing. A lot of variables to get to the end result.
Colin
Yup.. and a lot of THAT info, I do not yet even have a clue, as I do not yet have a boat.
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You said this was for a tugboat, so a displacement hull and generally quite a chunky one at that.
For a scale subject, the size and style of prop is often dictated to by the original boat. We can tinker a little with the pitch and sometimes the blade shape is tweaked a bit, but overall remains a faithful miniature version of the 1:1 item.
I tend to look at what would be my desired speed and work back from that.
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You said this was for a tugboat, so a displacement hull and generally quite a chunky one at that.
For a scale subject, the size and style of prop is often dictated to by the original boat. We can tinker a little with the pitch and sometimes the blade shape is tweaked a bit, but overall remains a faithful miniature version of the 1:1 item.
I tend to look at what would be my desired speed and work back from that.
I would tend to 100% agree... the thing is, I do not have a boat yet, and no idea what kind of boat would sport a 105 mm prop.
On another note: So far, I have assumed to be using a 15 cc single cylinder engine, and assumed that I would expect to get about 80 to 100 W out of that...
Stupid me... This thing is allready lying jobless somewhere around the home for about 2 years or so...
(https://www.youtube.com/shorts/LGYRdGOq5xg)
I still have quite a bit to modify on it, but it already HAS water cooling, a built on water pump, a built on starter and the flywheel is better suited to hook up to a drive system. I only would wish the flywheel would be a bit heavier...
But it should have no issues delivering 100 W whatsoever.
Imagine the run a bit more stabilized and regular, and the sound a bit more muffled...
How cool would THAT be?
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Meanwhile....
Itstarts to look like a 105 mm fourbladed prop, at normal pitch settings (around 1:1), would absorb in the neighbourhood of 80 Watt at around 2000 RPM.
I am going to spin slower, but have a significantly larger pitch range (estimated to be at least 1,5:1).
So I think that will match fairly well.
The purchase of a boat is also in progress, if all goes well, it is going to be a "Wouter Goedkoop" of 110 cm length and 32 cm beam. Displacement probably somewhere in the order of magnitude of 20 kilo, probably a touch more. That remains to be determined.
I probably need to work out the prop frame a bit, but only marginally so, to be able to install the Raboesch propeller.
(https://www.modelbouwforum.nl/attachments/img_1901-jpg.564757/)
(https://www.modelbouwforum.nl/attachments/img_1940-jpg.564758/)
A pitch limiter system is also in the making. This is a digital system programmed to determine pitch setting based on stick imput, and governor throttle output, with an adaptive deadband to minimize unnecessary pitch movements.
The engine is going to be a single cylinder, since I do expect the V8 to be a HUGE amount of work to get it to run right and reliable. The single I have experience with on how to get that right.
I will report back when things start to take shape.
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Well...
Things have taken shape, plans have been amended a little bit, and progress is slow but steady.
The boat has been purchased, it is an old "Wouter Goedkoop" (1950's era harbour tug, back then active in the port of Amsterdam).
Some cute details but not very skillfully built.
Most important is that the hull is strong, tight and well waterproofed, inside and out coated with Epoxy.
The internals are a bit of a mess, and I expect to have quite a bit of work to clear things out.
(https://www.modelbouwforum.nl/attachments/20240107_022530-1-jpg.566347/)
But the propeller.... Oh, Boy! What a beaut...
(https://www.modelbouwforum.nl/attachments/20240107_022541-1-jpg.566348/)
Most definitely very much "1980's technology" WRT manufacturing, but absolutely top notch in finish and precision.
Unfortunately, back then grease was the only option for constructions such as this, and the prophub needs to be completely filled with grease, so I will need to find a decent alternative that won't leave spots on the water.
The shaft is ball raced, but depends on a full grease filling for water tightness I think, as I do not see any rubber seals anywhere.
The shaft is supplied very complete with a VERY sturdy dog bone coupler, grease nipples (plural, there is a nipple supplied for fixed fitting to the tube, and a separate nipple that can be temporary fitted to the hub in order to top that off with lubricant, for which the hub has a plug that closes off the boss to fit the grease nipple.
The only thing I would have liked would be trust bearings in the pitch control mechanism, but those can be retrofitted.
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Dow Corning Rubber Grease or Penrite Rubber Grease has no affinity with water......I have used it in a 1:48 model ship stern tube gland tube bearing
It will migrate slowly out of through the clearance between the propeller shaft OD and the gland ID [0.002"], but stays as a small goop & easily cleaned after running
1.
https://www.google.com/aclk?sa=l&ai=DChcSEwjji9OkocqDAxVnKIMDHe7xC9QYABAMGgJzZg&ase=2&gclid=EAIaIQobChMI44vTpKHKgwMVZyiDAx3u8QvUEAQYByABEgKkmfD_BwE&sig=AOD64_32OukOBAwXwu2s8H27i4RwaQjk4g&ctype=5&q&nis=6&adurl=https://www.ebay.com.au/itm/166499645814?chn%3Dps%26_ul%3DAU%26norover%3D1%26mkevt%3D1%26mkrid%3D705-139619-5960-0%26mkcid%3D2%26mkscid%3D101%26itemid%3D166499645814%26targetid%3D1741701787178%26device%3Dc%26mktype%3Dpla%26googleloc%3D1000286%26poi%3D%26campaignid%3D18278742238%26mkgroupid%3D141565058112%26rlsatarget%3Dpla-1741701787178%26abcId%3D9301725%26merchantid%3D107329482&nb=0&nm=66&is=650x357&clkt=92&nx=61&ny=12 (https://www.google.com/aclk?sa=l&ai=DChcSEwjji9OkocqDAxVnKIMDHe7xC9QYABAMGgJzZg&ase=2&gclid=EAIaIQobChMI44vTpKHKgwMVZyiDAx3u8QvUEAQYByABEgKkmfD_BwE&sig=AOD64_32OukOBAwXwu2s8H27i4RwaQjk4g&ctype=5&q&nis=6&adurl=https://www.ebay.com.au/itm/166499645814?chn%3Dps%26_ul%3DAU%26norover%3D1%26mkevt%3D1%26mkrid%3D705-139619-5960-0%26mkcid%3D2%26mkscid%3D101%26itemid%3D166499645814%26targetid%3D1741701787178%26device%3Dc%26mktype%3Dpla%26googleloc%3D1000286%26poi%3D%26campaignid%3D18278742238%26mkgroupid%3D141565058112%26rlsatarget%3Dpla-1741701787178%26abcId%3D9301725%26merchantid%3D107329482&nb=0&nm=66&is=650x357&clkt=92&nx=61&ny=12)
You mentioned your thoughts on 0-rings powering the engine accessories as shown.........model size transmission toothed belts are used for the main drive on model off-road cars [1:16] and would be absolutely suitable to transmit the power on the engine to the accessories without failure....
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My Dow Corning Rubber Grease May 2009 reply number #10 and #14...................
https://www.modelboatmayhem.co.uk/forum/index.php/topic,16799.0.html (https://www.modelboatmayhem.co.uk/forum/index.php/topic,16799.0.html)
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Dow Corning Rubber Grease or Penrite Rubber Grease has no affinity with water......I have used it in a 1:48 model ship stern tube gland tube bearing
It will migrate slowly out of through the clearance between the propeller shaft OD and the gland ID [0.002"], but stays as a small goop & easily cleaned after running
1.
https://www.google.com/aclk?sa=l&ai=DChcSEwjji9OkocqDAxVnKIMDHe7xC9QYABAMGgJzZg&ase=2&gclid=EAIaIQobChMI44vTpKHKgwMVZyiDAx3u8QvUEAQYByABEgKkmfD_BwE&sig=AOD64_32OukOBAwXwu2s8H27i4RwaQjk4g&ctype=5&q&nis=6&adurl=https://www.ebay.com.au/itm/166499645814?chn%3Dps%26_ul%3DAU%26norover%3D1%26mkevt%3D1%26mkrid%3D705-139619-5960-0%26mkcid%3D2%26mkscid%3D101%26itemid%3D166499645814%26targetid%3D1741701787178%26device%3Dc%26mktype%3Dpla%26googleloc%3D1000286%26poi%3D%26campaignid%3D18278742238%26mkgroupid%3D141565058112%26rlsatarget%3Dpla-1741701787178%26abcId%3D9301725%26merchantid%3D107329482&nb=0&nm=66&is=650x357&clkt=92&nx=61&ny=12 (https://www.google.com/aclk?sa=l&ai=DChcSEwjji9OkocqDAxVnKIMDHe7xC9QYABAMGgJzZg&ase=2&gclid=EAIaIQobChMI44vTpKHKgwMVZyiDAx3u8QvUEAQYByABEgKkmfD_BwE&sig=AOD64_32OukOBAwXwu2s8H27i4RwaQjk4g&ctype=5&q&nis=6&adurl=https://www.ebay.com.au/itm/166499645814?chn%3Dps%26_ul%3DAU%26norover%3D1%26mkevt%3D1%26mkrid%3D705-139619-5960-0%26mkcid%3D2%26mkscid%3D101%26itemid%3D166499645814%26targetid%3D1741701787178%26device%3Dc%26mktype%3Dpla%26googleloc%3D1000286%26poi%3D%26campaignid%3D18278742238%26mkgroupid%3D141565058112%26rlsatarget%3Dpla-1741701787178%26abcId%3D9301725%26merchantid%3D107329482&nb=0&nm=66&is=650x357&clkt=92&nx=61&ny=12)
You mentioned your thoughts on 0-rings powering the engine accessories as shown.........model size transmission toothed belts are used for the main drive on model off-road cars [1:16] and would be absolutely suitable to transmit the power on the engine to the accessories without failure....
Thanks for the tip about the grease. Does it lubicate Brass and Stainless?
Right now I have filled the hub with a mix of EP2 grease and Steam Oil (steam oil makes the grease more goopy and does not wash off in water), but I don't know if I will stick with that.
I am not disconnecting the pumps because of the belts (plays a significant role in the decision, but is not the main reason).
Main reason is because I am going to run as low as possible RPM, I want to take any unecessary load off the engine. So I won't modify to toothed belt.
The starter (the intended engine has a built on starter) allready needs to drag along the prop plus shaft, better to keep its job as light as possible.
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Attached is one of the better MSDS for Red Rubber Grease, complete with technical data
One point is that it is listed as non harm to aquatic environment
It has totally difererent characteristics to EP2 lubricants when the grease is wipped or stirred in water
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Attached is one of the better MSDS for Red Rubber Grease, complete with technical data
One point is that it is listed as non harm to aquatic environment
It has totally difererent characteristics to EP2 lubricants when the grease is wipped or stirred in water
Thanks... Although I do not see real technical data on lubrication characteristics, material compatibility and area of application...
I think I'll play it safe and fall back on greases as used for outboard engines.
MEANWHILE....
The old sterntube had to be removed, and I happened to have a very tiny burner that came with my Portasol soldering set. That is a burner head only 8 mm diameter, and I could stick it IN the tunnel, leading the flame and gasses only through the metal tube, not charring the wood or paint or anything.
This burned the Epoxy that held the old tube in place within minute. First hurdle passed, but now the tube was loose in the hull, but it was not yet out, and I managed to work it backwards about 25 mm, then it stopped, but there was a flange of sorts on the wet end of the (Apparently home made) tunnel so it could not go out in forward direction either. Had to cut it through. No problem, I wasn't going to salvage it anyway.
A 12 mm drill up the rear of the hull cleared the way for the Raboesch tunnel&shaft.
I had to rework the rudder frame a bit in order to let the propeller blades clear the frame, and here she is...
(https://www.modelbouwforum.nl/attachments/20240107_230537-1-jpg.566442/)
(https://www.modelbouwforum.nl/attachments/20240107_230526-1-jpg.566437/)
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The propshaft has been mounted with heavy duty Epoxy (Araldite 2011, very similar to UHU Plus E300):
(https://www.modelbouwforum.nl/attachments/20240110_122731-1-jpg.566607/)
Waiting for the resin to set and cure.
The propframe has been reinforced to make up for the necessary clearance for the prop:
(https://www.modelbouwforum.nl/attachments/20240110_124052-1-jpg.566608/)
And I decided to add a few thrustbearings for the pitch control mechanism, which consistst of a sliding, not rotating bush around the shaft, pushing against two stoppers that are rotating with the shaft. One way or another that would lead to wear and play, regardless of the amount of lubrication.
Hence the trustbearings, to be placed between the bushing and the stoppers.
(https://www.modelbouwforum.nl/attachments/20240110_124717-1-jpg.566609/)
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Topic renamed from: Question about propellers.
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Thanks Martin!
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That Epoxy gives great results, but it is annoyingly slow setting, halting progress...
All that has been done additionally, was fitting the grease point to the tunnel.
(https://www.modelbouwforum.nl/attachments/20240110_223529-1-jpg.566724/)
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That wood looks very shiny, it's not oil soaked, is it? {:-{
(https://www.modelbouwforum.nl/attachments/20240110_223529-1-jpg.566724/)
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I made a few small mods to the transfer linkage of the pitch control.
As per design this linkage would consist, aside from the lever, of a stationary slider on the shaft, locked in between two stopper rings, the stationary slider pushing against the rotating stoppers (metal to metal contact with a fair bit of force), prone to wear and play.
So I installed two ball raced thrust bearings on each side of the slider one. Less friction, and no wear and play.
The slider got a grease hole to the inside, and a groove in the running bore, spreading grease over the lengthe of the slider, and eventually to the inside of the thrustbearings.
https://www.modelbouwforum.nl/attachments/20240111_065646-1-jpg.566739/
I hope this will be a significant improvement.
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That wood looks very shiny, it's not oil soaked, is it? {:-{
(https://www.modelbouwforum.nl/attachments/20240110_223529-1-jpg.566724/)
No... fortunately not...
One of the previous owners, or perhaps the builder, nobody knows, has treated the inside of the hull with a resin, and has done so very sloppy... Lots of grass, dust, dirt and what not in the resin, and the resin has pooled at the bottom.
Aesthetics were not a priority apparently...
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First in-water test... Cordless drill for temporary drive
https://www.youtube.com/watch?v=koKyiab5nTo
quite a bit of water movement. No idea about bollard pull, but it is hard to keep the boat still when reversing the pitch.
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Propframe "rerouted"
(https://www.modelbouwforum.nl/attachments/img-20240112-wa0002-1-jpeg.566840/)
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The next step:
(https://www.modelbouwforum.nl/attachments/20240228_190149-1-jpg.573912/)
(https://www.modelbouwforum.nl/attachments/20240228_190248-1-jpg.573913/)(https://www.modelbouwforum.nl/attachments/20240228_190414-1-jpg.573914/)(https://www.modelbouwforum.nl/attachments/20240228_190424-1-jpg.573915/)
(https://www.modelbouwforum.nl/attachments/20240228_190443-1-jpg.573916/)
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I have not kept up here for a while,
my bad...
Apologies for the pictures being links but here are some from the engine build:
First step in the build was to fit the liners into the cylinder block. In order to do that, for each cylinder three O-rings sealing off the cooling water jacket needed to be installed. These things are pretty filigrane (string diameter about 0,7 mm), and the bores are only about 17 or 18 mm.
(https://www.modelbouwforum.nl/attachments/20240310_114830-1-jpg.575042/)
I could barely get my index finger into the bore whatsoever, so it was a lot of fussing about with one pinky and a toothpick to manipulate the rings in their slots.
(https://www.modelbouwforum.nl/attachments/20240310_114748-1-jpg.575041/)
A bit of grease on the liner serves to allow the liner to be slid into the bore, and care must be taken that the bevelled edge passes the rings properly, or liner and block will act like a scissors and cut the rings.
(https://www.modelbouwforum.nl/attachments/20240310_115421-1-jpg.575043/)
There are 12 O-rings needed, and 13 in the kit, so you can only make ONE mistake...
Next step was the installation of crankshaft (of which I did not really take pics, sorry) but it was pretty straightforward: a ball bearing on the distribution side of the crankshaft, and since clearances are extremely tight, a bit of fiddling is needed to jiggle the crank into position.
About 5 mm before the crank is in position, the two halves of the brass support bearing heed to be placed, and although an easy understandable operation, due to the tight clearances and fit, this is a bit of a hassle. Once in place, the crank can be pushed home, and a single M3 bolt locks the support bearing assembly against rotation.
In my case, the crank turned over extremely smooth, no fuss, no fiddling, no search for undesirable friction.
After that, time to install camshaft and distribution.
This part is really beautifully made, with proper keyways and keys, all extremely miniature and ultra-realistic.
(https://www.modelbouwforum.nl/attachments/20240310_203943-1-jpg.575134/)
(https://www.modelbouwforum.nl/attachments/20240310_212239-1-jpg.575133/)
(the hole in the large gear has a reason: Once fitted, it is impossible to pull the gear off due to lack of purchase. The bearing of the camshaft is locked in place with two screws, so the hole serves to remove these screws, in order to pull camshaft and gear together. There are no timing marks, the keys serve that function)
This was the first point where I encountered poor fit: the keys were ever so slightly too large and I had to file them down a touch with a needle file, which is not that easy to do given that the key was about 1,5 x 1,5 x 5 mm. How do you hold that in a vise?
(you don't... between the fingertips and accept that you're going to loose a bit of epidermis on the fingertips... :p )
Then the conrods and pistons need to be joined. Another not too impressive part of the engine: According to the description, the bosses in the piston should be a bit different in diameter, with one slide fit and one press fit. The idea is to fit the gudgeon pin into the slide fit, position the small end, then carefully push the gudgeon pin home, with the addition of a bit "anaerobic 242/271" (more commonly known as "loctite" :D ).
Only one piston showed these characteristics, the other three pistons had no noticable difference in fit and were slide fits.
One of the gudgeon pins even was a tiny bit too large and I had to carefully grind that one down ever so slightly.
So I fitted all four gudgeon pins with loctite, something I raise my eyebrows over to be totally honest.
There was no space to place Teflon pads like in most normal model engines.
Oh well, nothing I can do about that...
The piston rings are pretty filigrane too, and I was worried that fitting the 2nd ring (which has to pass the first ring) would be problematic, but I was surprised how easy each ring (all 8 of them) went in their allocated slots.
(https://www.modelbouwforum.nl/attachments/20240311_172413-1-jpg.575201/)
Next step, the pistons need to be placed in the liners and the conrods hooked up to the crankpins.
First a drop of oil in the liner, on the piston, on the small end and the crankpin.
Next the big end bearing is opened. Care to be taken that only one rod is opened at a time so as to not mix rods and caps, because the rod and cap are paired. The caps also should be fitted in the same position as they came off, there is a tiny notch indicating that position.
The big end bearing has an oiler hole in the rod, the oiler hole should be on the side of the oil gallery.
When fitting the piston into the cylinder, the liner has a tiny bevel topside, the first ring easily slides in with a bit of pushing the ring in with a toothpick.
The pitfall is getting the top ring in: It just so happens that at the same point where the top ring needs to pass the top of the liner, also the conrod meets the crankwebs at the tiniest bit of misalignment. If you don't catch this interference, there is a risk of damage to the bigend bore and the landing face of the big end cap when you push too hard in an effort to get that darn ring (which is NOT the cause of resistance) into the liner.
REAL care must be taken that the rod is hanging free between the webs instead of interfering with them.
Once that hurdle is passed, pushing everything home and fitting the bearing cap is straightforward.
(https://www.modelbouwforum.nl/attachments/20240311_174651-1-jpg.575202/)
Now immediately it becomes clear how much friction piston rings generate: that smoothly turning crank became increasingly resistive with every piston installed.
That should cure itself during break-in I guess.
Fitting the flywheel casing (which also holds the pre-fitted DE bearing of the crankshaft, is nothing worth mentioning, and ditto the fitting of the largely pre-assembled head. I am a bit sceptical about the non-metallic head gasket, but it is what it is, more about that later.
Fitting the cam followers, pushrods and rocker arms also is very uneventful, but one thing that stood out: the designer took a shortcut for the cups holding the pushrods. Normally, pushrods are fitted with hemisphere ends, and rest in properly fitting cups. On this engine, the rods are rounded, and the cups are.... the internal hex holes of Allen head bolts... {:-{ :((
It will probably work just fine, but hey...???
The downside of this is that valve clearance probably will need frequent adjustment initially because of the rod-ends mating with the Allen heads, working their way in a bit, and that's the thing: adjustment needs to be done with needle nose pliers acting on those cups, there are no slots in the threaded ends of the adjusters. Oh well, that 1000 Euro price HAS to come from somewhere, right?
Installing the starting gear is a real PITA, because the one way bearing in the main starter wheel is keyed to the shaft and a fairly tight fit.
Pushing this home while only being able to turn one way to align the slot, while at the same time trying to make the teeth of the intermediate gear mesh, well, it took me several hours before it suddenly and without identifiable reason clicked into place...
And that's where I have landed now...
<iframe width="560" height="315" src="https://www.youtube.com/embed/h7xRAO7QpUY?si=98UIDTsX_pkxOdg6" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
https://www.youtube.com/watch?v=h7xRAO7QpUY (https://www.youtube.com/watch?v=h7xRAO7QpUY)
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So on with the next steps, the fluid circulation devices (AKA "pumps").
The oil pump is a really tiny affair:
(https://www.modelbouwforum.nl/attachments/img-20240321-wa0008-1-jpeg.576174/)
Not much to tell about it, it worked at first assembly. I am not sure if the oil flow will be sufficient, I will have to judge that at the first engine run.
Constructionwise not much remarkable about it, closed housing, single oillite bearing outside of the oil space, a shaft seal behind the oillite beearing to hold the oil in the system. In general the design is rather simple and no-nonsense.
The oil pump can pivot around its lower mounting point and doubles as a belt tensioner. The "belt" is a set of thin long O-rings
The waterpump was a different affair...
The existing design of the cylinder block was prepared to accept a direct bolt-on centrifugal waterpump that could not convince anyone with its pumping capacity, so the designer felt that a gear pump had to be fitted into the existing layout, and to be totally honest, the result is not what I would have come up with.
The pump housing consists of two parts, sealed off by a thin paper gasket, which due to the inconvenient layout of the fluid channels does not really have the simplest of shapes. Dry, it is perfectly manageable, but once fluid has been in the system, and the gasket is wet, it turns into a fragile and difficult to handle scrap of paper vaguely resembling the consistency of a boiled leaf of spinach...
Virtually all other gaskets have been stamped out of Teflon sheet, and are much easier to handle, I have no clue as to why the designer here opted for paper, it really is the wrong choice of material IMHO.
That would not be so bad if the pump could be assembled and boxed up as a separate bolt-on unit, but here is where the designers really messed up: The three bolts that hold the two pump parts together ALSO hold it to the engine block. In other words, assembly of the pump AND fitting it to the engine block are one single operation, which is made more difficult due to one of the bearings of the driven shaft being placed in the engine block and not in the pump itself. This makes it virtually impossible to keep the (previously wetted) split-gasket in its proper place while manipulating one other gasket (between pump and cylinderblock), two pump halves, a drive shaft, AND three bolts...
I normally am a fairly patient messer-abouter with teeny tiny engine parts and delicate mechanisms, but this one tested my patience and dexterity to the limit and (a touch beyond, actually)... I mean: it took me the better part of 45 minutes to assemble the pump because I kept noticing the gaskets slid out of place during assembly. A Teflon splitgasket would literally have made this job a one minute affair... :( :( :(
To make matters worse: I think Cison has some issues with their boring and drilling department, because the gear and shaft are supposed to be an interference fit. They were not... So during the initial test the pump did not work... Dammit! That's when I found out that disassembling the pump in wet condition is a nightmare.
I found the gear to be loose on the shaft, so I took the Dremel and ground a few notches in both the shaft and the gear bore, degreased the parts thoroughly, coated shaft and bore with heat-curable Epoxy (UHU Plus E300), assembled the shaft and gear taking care to properly locate the gear on the shaft, and baked it in the oven at 75 degC for about 2 hours.
The notches serve to give the Epoxy some purchase, but care must be taken that the fit is not affected, so the notches have to be very local.
This solved the issue, but the split-gasket being near impossible to locate properly during assembly, probably there was a bit of gasket stuck between the gears, which I carefully pried loose by turning the pumpshaft by hand about 10 turns.
The resulting "drill powered" testrun with liquid in the system showed a puff of dark dirt coming out with the first dash of cooling liquid from the return line.
I ran the pump like that for a few minutes, then flushed with fresh and clean fluid, and ran the pump some more.
FWIW I am using off the shelf automotive "ready to use" cooling liquid (in my case Gulf XXL, but I don't think that is really important) primarily because of its corrosion inhibiting and lubricating properties
https://www.youtube.com/watch?v=WQtj0qeJ4Go (https://www.youtube.com/watch?v=WQtj0qeJ4Go)
At this speed, I measured a volume flow of about 100 ml/minute, and although I do not know the exact RPM of the cordless drill, I estimate it at between 1000 and 1500. The engine is intended to run 1500 governed, and given the pulley ratio (approx 2:1), I should have about double that flow in running conditions. A careful estimate would hint at a delta-T of about 15 deg C over the cylinder block.
After this "break in" the pump turned over smooth enough for not to cause slippage of the belts.
At this point in time, here's what the engine looks like right now:
(https://www.modelbouwforum.nl/attachments/20240321_232338-1-jpg.576175/)
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Fitting the intake manifold was the next job and equally similar to pulling teeth...
The manifold itself is a fairly decent piece of 3D-printed metal.I have no clue how strong or brittle this stuff is, so it was out with the silk gloves...
The availlable access for tooling is minimal, the manifold is attached to the head by 8 bolts in 4 flanges, with O-rings to seal the intake tract off.
First step is to lay the engine on its side and place the O-rings in their rather shallow chambers, then fit the manifold.
In order to fit the manifold you need to first locate all 8 bolts, and those bolts are slippery, not easy to grip with pliers or pincers.
(https://www.modelbouwforum.nl/attachments/20240322_120325-1-jpg.576209/)
Then you need to hold the manifold with one hand in place, while the other hand needs to get each bolt going on its first thread, which is tricky because they are allen head bolts but there is only marginal access for a normal schrewdriver type allen wrench.
Only tighten the bolts one turn at a time, because screwing in the first bolt, lowers the manifold in place, and the remaining bolts now sticking out high, become unreachable for further tightening.
And all this time you HAVE to hold the manifold up with the other hand, in order to prevent dislocating one of the O-rings...
(https://www.modelbouwforum.nl/attachments/20240322_120736-1-jpg.576208/)
I had to shorten an old Allen Key in order to be able to reach the bolts.
(https://www.modelbouwforum.nl/attachments/20240322_121137-1-jpg.576215/)
The carb visually looks different from normal glow style carbs, with several things that looked like adjustment possibilities, so I had high hopes that this would be some special gasoline adapted design, but on closer examination, it turns out it is basically an old faxhioned airbleed-carb, just built a bit unusual. Not very optimistic about that, since previous experience with airbleed carbs and gasoline is not very faith inspiring.
(https://www.modelbouwforum.nl/attachments/20240322_121832-1-jpg.576216/)
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There is one thing I have not yet mentioned here, which, when I found out was a bit of a bummer...
According to the info on the Stirlingkit.com page where I bought the engine, the sparkplug size was 1/4"-32, the common glow plug thread size.
Since I allready own a couple of 4-cylinder ignition sets and literally a dozen or so spare plugs (all my planes run converted ex-glow engines, among them at least one twin and a 5-cylinder radial, so one tends to keep some stock:D :D ), I ordered the engine without the starter kit that contains the ignition, plugs and a radiator, which of course I thought I would not need at all...
My dissapointment was great when I found out that during the revision of this engine, in early 2024 Cison in their infinite wisdom decided to use an even smaller spark plug, and since to the best of my knowledge those plugs are not manufactured anywhere else, Cison also is the sole supplier of this (to me unknown) plug, which seems to have something like an M5 fine thread series thread or something.
Although it is possible that these are Rimfire Viper series plugs which are supposed to have 10-40UNEF thread, that are close to 5 mm external. But I cannot find that thread size anywhere else.
Anyway, that was a bummer, but I have to say, Stirlingkit appears to be VERY customer oriented, since I posted a review of the engine mentioning that fact, and immediately (within 6 hours or so) received an e-mail, and the follow-up on that e-mail conversation was swift, to the poiint and friendly.
Can't say anything else.
But of course, now I need to wait for the plugs to arrive...
Oh well, gives me time to set up a testrig for the engine. Planning to hook up an old unused starter motor to serve as a variable load (a variable resistor should allow to it to function as a varable load...)
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The engine assembly is done, apart from the ignition system.
The cooling pump I allready showed, here's the functioning of the lube oil pump:
https://www.youtube.com/watch?v=w5AhLWr3ksQ (https://www.youtube.com/watch?v=w5AhLWr3ksQ)
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The engine is done, apart from the ignition. So that part of the project is temporarily halted.
Since it is crappy weather anyway, I thought I would go prepare the old hull because there's a lot to do there as well, and then I am thinking about installing a bilge cooler tube (maybe I need two, no idea yet), I need to start thinking about the rest of the cooling system (expansion tank, temperature control valve, etc etc), a fuel supply (probably a gravity feed fuel tank and a floatbowl from an old moped carb or such), exhaust system with dirt collecting tank, servo's, electricals, ballast and much more.
So I turned the hull upside down and... :(( {:-{
(https://www.modelbouwforum.nl/attachments/20240324_092129-1-jpg.576433/)
(https://www.modelbouwforum.nl/attachments/20240324_092209-1-jpg.576434/)
Looks like I need to break out the 180 grit waterproof, because that coat of paint ain't waterproof no more.
Oh well, the waterline was located wrong anyway (too low, the boat needs to be ballasted quite a bit deeper than that) and as I said, it's crappy weather, nothing better to do anyway.
Gonna be a very messy job... <*<
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Paint or Hull crack? .... :((
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Paint or Hull crack? .... :((
Paint and maybe the bondo, but the wood is intact as far as I can see...
But despite sanding down, the cracks kept sucking up paint.
So I applied a first pretty heavy coat, kept the cracks "wet" with paint for a while, and after 2 hrs applied a 2nd heavy coat, and the 2nd coat the cracks did barely draw in any paint.
With a bit of luck it'll be allright. If it isn't, I'll have to gouge out the cracks and fill them with 2 component glassfilled bondo.
While I was at it, I corrected the horribly misplaced "waterline".
Not bad, even if I say so myself.
(https://www.modelbouwforum.nl/attachments/20240324_173712-1-jpg.576662/)
(https://www.modelbouwforum.nl/attachments/20240324_174042-1-jpg.576663/)
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OK... the ignition parts landed this morning, so they could be on my doorstep as early as Tuesday (but probably not... :p ).
So I need to get the testbed ready...
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Apologies, I let posting here slide a bit in the last couple of days...
Monday around noon, to my amazement a courier knocked on my door, and there it was....
First of all those elusive tiny sparkplugs...
For those of you guys familiar with glow engines: On the right is a sparkplug in the standard thread for glow-engines (1/4"-32) and on the left is the amazingly tiny things this engine requires...
(https://www.modelbouwforum.nl/attachments/20240325_222153-1-jpg.576898/)
The nasty thing was that the kit as received, still basically was intended for the "large" sparkplugs In fact, it was a kit containing 4 large plugs, and the new smaller plugs were added in. Have to hand it to them chinese, no extra cost so I have 4 plugs 1/4"-32 for free basically), so the rubber caps supplied were loose on the new tiny plugs.
Also, for RF supression, 4 resistors 5K were supplied. Regular resistors, and how you want to install them is left to the imagination.
So here's what I did:
I cut one of the pins to half length, and ground it sharp using the Dremel.
(https://www.modelbouwforum.nl/attachments/20240325_230726-1-jpg.576902/)
This sharp end is stuck in the end of a HT lead
The other pin is coiled up using a small needle-nose pliers
(https://www.modelbouwforum.nl/attachments/20240325_230946-1-jpg.576903/)
Now I cut about 5 mm of silicone tubing (3 mm inner dia, 1 mm wallthickness) to make the plugboot fit snug on the porcelain of the plug, and stick everything together.
(https://www.modelbouwforum.nl/attachments/20240325_231107-1-jpg.576906/)
(https://www.modelbouwforum.nl/attachments/20240325_231123-1-jpg.576907/)
(https://www.modelbouwforum.nl/attachments/20240325_231209-1-jpg.576908/)
(https://www.modelbouwforum.nl/attachments/20240325_231352-1-jpg.576909/)
Now I had the issue, that the instructions (not supplied with the ignition kit, but on the vendor's website) still mentioned a ground cable, but this info was valid for a previous version. The new version did not have a groundcable, but silly me, it took me a day to figure out HOW that would work, and why.
Since I am slightly autistic (fo'realz) I did not dare powering up the ignition until I was sure I would not blow up the Hall sensor arrangement.
Next step was fitting that arrangement on the engine, and I've got to say, this all went together perfectly. Pretty nice design!
(https://www.modelbouwforum.nl/attachments/20240326_090351-1-jpg.576936/)
I was initially dissapointed that Cison does not use the RcExl (another chinese manufacturer of Model engine ignitions) standardized connectors, because I have a timing gadget for that brand...
But to my great surprise, the Hall sensor arrangement was fitted with LEDs, so this thing really is a doddle to set the timing right.
https://www.youtube.com/shorts/nz96OEWUXA0
Soo yesterday evening, I mounted the engine on my teststand, with just a tank for the coolant, no radiator yet (I have one, supplied in the ignition/starter kit) because that radiator has connections totally different from the connections supplied with the engine. So I have to first figure out how to fix that.
But I was guessing it would take a minute or two to warm up 250 ml of coolant, so for short runs, no problems.
Well... No more beating around the bush, no more delays:
https://www.youtube.com/watch?v=-GnA-3U9ap8
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I was counting on the heat capacity of the coolingwater tank to run the engine for short periods, but 250 ml of cooling water reaches about 70 dgrees within 2 minutes, and takes forever to cool down.
So I did include the fan and radiator in the cooling circuit. Basically, this radiator is laid out for just the heat generated during no load operation at very moderate RPM. It sure as heck won't be able to dissipate the heat generated when the engine is under load.
"As is" with zero regulationg or temperature control, the fan at full power will stabilize the temperature of the idling engine at about 60~70 deg C at the engine outlet.
https://www.youtube.com/watch?v=-kXbG0_pZ3A
This allready results in a delta-T over the engine of approx 25~20 deg C, so the cooling water flow is marginal as well.
Oil temperature seems to stabilize at about 60 degrees under these conditions, which is fair enough.
Although I most likely will run the engine with original pump set-up during the break in period, but will change to electrically driven pumps for the final installation. Because the first set of belts allready have snapped...
I ordered NBR 90 shore O-rings from a local supplier, 50 pieces, soi I can break a few...
Edit: just a few additional remarks...
-The engine is pretty much vibration free, starts extremely easy and is smooth. With a decent muffler, the sound is at very acceptable levels and I have the feeling a decent exhaust system also affects running behaviour in a positive way. Throttle response can only be described as "snappy" and "enthousiastic"
-The engine delivers an unbelievable torque allready at low RPM, if I had to estimate it might not beat a Robbe Power1000, but it darn well comes pretty close. In all fairness, I was amazed, especially given that the engine is yet a long way from being broken in.
It now has about 20, maybe 25 minutes of runtime, but compression also allready is really impressive.
-There are lots of small issues with it, but the basic design absolutely has potential. Those issues are a challenge to fix (if you're into that kind of thing. I know I am...) but once those fixes are done, it is pretty clear the design allows for to use this engine as a serious power plant for practical application, anywhere where "racing" or "speed" are at the bottom of the priority list. This thing seems to be made for pulling stumps. This thing can drive large boats.
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Since I cannot run the engine due to lack of "belts", and I had to do something due to lack of a better thing to do, I wasted a little bit time on an oil cooler of sorts.
I do not have the faintest clue it would need one in the first place, but given that virtually anyone running this engine is is either running it on the bench (no load whatsoever, or in a car model (exposed engine, air flow when at speed), but my application is in the enclosed space of a boat hull, I can imagine that there is very little empirical information availlable about oil temperatures and such.
The thought was that if it won't help, it won't hurt either, so first a little bit of figuring out how to arrange it, I came up with this:
(https://www.modelbouwforum.nl/attachments/20240328_190438-1-jpg.577308/)
Temperature controller is trying to keep enigne outlet temp constant, so increasing load will result in lower inlet temp.
I can select the coolingwater pump speed, so I can determine the range of inlet temperature (this is a fixed setting to be determined on the testbed)
By connecting the LO cooler in series before the cylinder block, and optimizing the waterflow through the engine, theoretically the oil temperature will also be around that range. It won't get colder than the cooling water inlet temperature, and it won't get much hotter either.
What is more: At increasing load, the inlet temperature is lowered by the temperature controller, so oil cooling is "controlled" without adding a 2nd control loop.
Again: No idea if it is needed, but it is just fun in itself figuring out stuff like this.
So I bought some brass tubing 6, 5, 4 and 3 mm OD, wall thickness 0,5 mm.
The outer shell is 6 mm tubing, the oil tube is 3 mm (2 mm ID like the rest of the oil tubing), the water connections are 4 mm OD (so 3 mm ID like all the coolingwater tubing) and the "bulkheads" are short rings of 4 mm and 5 mm tubing
(https://www.modelbouwforum.nl/attachments/20240331_162927-1-jpg.577678/)
The water connections are silverbrazed to the shell, the oil tube and bulkheads are Epoxied in with UHU Plus E300, oven cured.
In front of the engine for an impression of size:
(https://www.modelbouwforum.nl/attachments/20240331_183700-1-jpg.577708/)
And installed:
(https://www.modelbouwforum.nl/attachments/20240331_185409-1-jpg.577709/)
Cooling surface is approx 10 cm2
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So...
The wait was long and frustrating, it always is when you really REALLY want something, but the belts arrived early in the afternoon.
The good news was that I measured correctly, the bummer was that apparently I overestimated the quality (hardness) of the originals.
I ordered 90 Shore hardness, and although both string diameter as well as length were spot on, the new rings were extremely tight.
So instead of both belts driving both pulleys simultaneously, I let one belt drive the waterpump and the other drive the oil pump.
Due to the tighter fit in the pulley grooves, there was no visual slippage, so off we go, fuel, water, oil, electricity and fire it up.
The engine had about 20 or so minutes of runtime previously, and those were a bit interrupted with issues with the cooling pump (leakage, and when fixed the pump turned a bit stiff which killed the original belts).
This first run of today (3rd run overall), of about 20~25 minutes, burned 100 ml of fuel (still 50:1 ratio), and starting with clean sump oil, at the end of this run the oil appeared a bit too dark for my liking, so I changed the oil. There was no noticable oil consumption. The old oil was dark but not black and I did not see any sign of wear particles
The waterpump remained completely dry, and the belt had no issue with the stiffness of the pump, so that was a good thing.
I saw a minor leakage on the oil pump, it's not from the shaft seal but so far not yet identified or remedied.
The oil cooler seems to work, the oil temperature (measured on the oil pan) appeared to closely follow the water inlet temperature. So that is good also.
Total Runtime at this point about 45 minutes.
https://www.youtube.com/watch?v=zrU1uKIq4sY
The 2nd run of today (4rth overall) was about 30 minutes on 100 ml of fuel, because I leaned out the engine quite a bit.
Now the carb started to show the same nasty habits as the one on my gasoline powered Krick Alexandra (see "pleasure and sports boats"), very poor fuel metering capability: Fuel/air ratio remains nowhere near constant over the throttle range, forcing the user to set a slobbering rich idle in order to be able to rev or deliver power. But since I don't want to rev, and I wanted to brak in the engine as clean as possible, I set the mixture as lean as it wanted to go.
Resulting in fairly smokefree running, firing on all 4 barrels and a decent run quality (regularity).
This run brought the total runtime to 1 hr and 15 minutes, and the oil appeared clean enough that I decided to do another run with the same oil
https://www.youtube.com/watch?v=nIBzI1fCJ48
The lrd run of today (fifth overall, totalling 1hr 45 min) was not filmed, and nothing noteworthy happened.
At the end of the day I still had a tiny dash of mixed fuel, which brought total runtime to 2 hrs.
During this run I tried to get the lowest consistent run with the leanest possible mixture.
Take a look at the carb opening size... That's a 20,5 cc engine drawing air through that tiny opening...
https://www.youtube.com/watch?v=Yh-zcVJ9ohE
I am absolutely happy with how slow the engine wants to go without any modification whatsoever, and it still allows for some static load at this RPM.
Pretty sure it will pull the submerged prop at neutral pitch at this RPM...
The carburettor is going to be a challenge (but I have seen those before) but all in all the engine appears to be quite a strong one.
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Could the carb problems be partly due to it's position at the end of the intake duct, this gives uneven distances between the carb and the cylinders. Therefore fuel takes longer to get to the end cylinder than the near one. Full size 4 cylinder engines will have the carb in the center of the intake duct giving a more symmetrical feed.
Jim
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Not as far as I can tell. Although the shape of the intake manifold to me also seemed a bit strange, as far as I can tell all four cylinders fire pretty even. There is no irregularity in the powerpulses and the echaust headers seem fairly evenly hot.
What I do know is that this specific type of carb has zero tendency to maintain a constant fuel/air ratio. Any change in parameters (throttle position or RPM or the relation between those two) the fuel/air ratio changes also. This forces the user to set the needle for the leanest practical condition (which is full throttle and high RPM) making ALL other throttle positions and RPM's rich to extremely rich. This in turn will cause the engine to load up.
There is a relative simple way to improve this, but the (for me irrelevant) downside is that the usable throttle range narrows considerably, which is OK, because I do not need 9K RPM and 3 horsepower. I need 1500 RPM constant, at varying load, and within this small sub-range of parameters, I need an as consistent as possible fuel/air ratio, in order to keep the exhaust as clean as possible: Nobody is going to like a boat that belches out blue foul smelling exhaustgasses and trails oil all over the pond.
That adaptation consists of a carefully calibrated air restriction upstream of the throttle valve. Ideally that restriction does not have any effect at no-load condition, but when load is increased it should be large enoug to allow for that load, but small enough to create just a tiny pressure drop. increasing fuel draw in ratio with the increase in air induction.
It works on the single cylinder fourstroke in my Alexandra, it should work here.
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Last week I wrote:
This allready results in a delta-T over the engine of approx 25~20 deg C, so the cooling water flow is marginal as well.
I ordered NBR 90 shore O-rings from a local supplier, 50 pieces, soi I can break a few...
Yesterday I noticed that the delta-T was only about 8~10 degrees C and I can only conclude that the original belts, that were pretty stretchy and loose, allowed for some serious slippage on the pulleys. I see more signs of an increased waterflow, but they are circumstantial at best, not rock-hard proof or such...
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Lovely little engine! Love it.
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Lovely little engine! Love it.
You can own one too if you want... ;)
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First logistical announcement: The last video I posted, of the engine idling, I have finally been able to measure that RPM and it is below 750 RPM.
It actually amazes me.
Meanwhile I noticed that heat transfer to the carb affected running, and a heat insulating sleeve made out of Teflon improved things significantly. I need to re-do that with POM as working material.
Also, something I noticd was that the reockerbox basically was only lubricated by the smell of oil, and I don't like dry moving parts.
So I thought I might be able to fit an oil gallery over the rockers. Measurement confirmed that there was 2,7 mm clearance between rockers and cover, enough to fit a 2 mm brass tube in the cover.
In this tube, careefully aligned to run directly over the fulcrum shaft, 4 tiny 0,8 mm holes were drilled, located centered above each pair of rockers. The oil will drip on the shaft and spread from there.
This would look a bit like this:
(https://www.modelbouwforum.nl/attachments/20240410_215050-1-jpg.578659/)
Oil supply was branched off from the main line, by silvrbrazing a "T" out of 2 cm of 3 mm tubing and 8 cm of 2 mm tubing. After brazing and quenching brass gets as soft as copper. So easy to bend the 2 mm line such that it connects with the oil gallery.
(https://www.modelbouwforum.nl/attachments/20240410_220416-1-jpg.578660/)
And if you look closely, when I pull the filler cap, you can see some oil flowing over the rocker arm, oil that was not there before...
Valve lubrication for CISON OHV L4-205 (youtube.com) (https://www.youtube.com/watch?v=TerYHyLwpzs)
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"only lubricated by the smell of oil" {-) {-)
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Well, the valve lubrication was a bad idea: Heavily smoking engine and rapid drop of oil level, so that idea can be discarded.
Next issue will be carburettor temperature control.
The way the carb is fitted, direct metal to metal in the intake manifold, results in massive heat to the carb as soon as the hot engine stops, making a delayed restart impossible: Either immediately, or wait until things have cooled down completely.
When running, things tend to get inconsistent bcause of this: Every time the throttle position is changed, the balance between heat supply through metal-to-metal conduction, and the heat removal through evaporating fuel is disturbed, leading to wandering RPM.
A thermal isolator has an immediate positive effect on this, but the downside is that today (miserable cold weather with high humidity) I saw signs of carb freezing.
I don't expect this to become an issue in the boat (enclosed space, nice warm and comfy) but for benchtesting most definitely I need to adress this.
So next step will be active carb heating (piece of brass tubing epoxied to the carb body, cooling water return routed through this). Can be easily connected or disconnected, and the great thing about it is: when the engine runs, there is virtually immediate carb heating, when the engine stops, so does the cooling water flow, and heat soaking of the carb should be a non-issue.
Now I can hear you guys thinking: If you won't need it in the boat, why bother? but I can assure from exoperience that it is pretty imperative to go through all this in order to end up with a reliable engine as a final result.
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This project hibernated for almost 9 months...
Looks like slowly the drive is coming back:
A few minutes with a blowtorch annealing brass tubing, and a little bit free-hand bending gave me this:
(https://www.modelbouwforum.nl/attachments/20250119_190719-1-jpg.607300/)
And two minutes with the cordless drill resulted in this:
(https://www.modelbouwforum.nl/attachments/20250119_191206-1-jpg.607301/)
Now it's a matter of a few distance pieces, and a decent dollop of Epoxy, and they should be sealed up.
That's how you make bilge cooling... :D
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Excellent! Welcome back .... :}2
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After a night of curing:
(https://www.modelbouwforum.nl/attachments/20250120_101306-1-jpg.607324/)
It is pretty difficult to keep the curing epoxy under control, so on close examination unfortunately a few big "blobs and sags" which I am hesitant to try and remove, worried that I might pull the paint off.
Right now, each tube is approx 43 cm (17") of exposed length, and at a diameter of 4 mm, that means a total exposed surface of about 105 cm2 or 16,5 sq.in.
At the amount of heat I expect to dissipate (I am guessing in the neighbourhood of 500W), and with water-to-water exchange, I expect this to be enough.
Possibly (but that ould be a real stroke of luck) close enough to function acceptably without temperature control
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My biggest fear....
was that the starter would be unable to pull the additional resistance of the (rather heavy turning) ancient Raboesch controllable pitch propeller.[/size]It was something I had zero options to test until AFTER at least a partial installation.So with great relief I can present you guys:
https://www.youtube.com/watch?v=60cVvXRJz4w
Reason for the stiff turning is that the shaft and prophub basically are completely stuffed with grease, AND the shaft basically has zero runhours (Raboesch back then mentioned in the instruction leaflet that the shaft and pitch control could be running pretty heavy until a few hours of operation should make things run in, knead the grease a bit and things would lighten up.
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Floorplate with driptray, in case of oilspills (the tray should be able to easily hold the contents of the sump 2 times over with a margin).
(https://www.modelbouwforum.nl/attachments/20250120_200527-1-jpg.607390/)
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Yesterday, I brushed on a few layers of filler and 2 layers of Glitsa polyurethane floor laquer. "poured some over it" could be a better word...
This morning, a few holes drilled and a few insert-nuts on the underside, and voilá... An engine on its foundation!
(https://www.modelbouwforum.nl/attachments/20250121_070501-jpg.607418/)
Now, it would of course be mighty nice if the engine could be removed and placed complete with its floorplate, so...
(https://www.modelbouwforum.nl/attachments/20250121_070511-jpg.607419/)
Hmmmm should fit...
ZIG
(https://www.modelbouwforum.nl/attachments/20250121_070518-jpg.607420/)
ZAG
(https://www.modelbouwforum.nl/attachments/20250121_070525-jpg.607421/)
ZOOM
(https://www.modelbouwforum.nl/attachments/20250121_070556-jpg.607422/)
A few simple woodscrews to fixate the floorplate in location should do it, as the engine itself is running fairly balanced and vibration free, but I'll have to think up a convnient tie-down set up.
Now the big jobs begin, the "growth" of the systems around the engine.
Still to do:
-Fabricate and install an RPM sensor for the governor
-fabricate and install a throttle servo bracket
-install the fuel tank and supply system
-install coolingwater expansion tank, piping, and possibly a temperature control
-Install ballast-batteries(I have a surplus of big dry lead batteries, and the boat requires a LOT of ballast, the idea is to install 2 x 6V 7 Ah for RX and separate ignition, and 12V 7 Ah for starting and other possible auxiliaries in the future, like a towing winch
-install the starting and ignition system
-install rudder and pitch servo. Especially the pitch servo is going to be a mechanically heavily stressed linkage.
-Fitting RX and in general, programming the entire set-up
-build and install an exhaust system, which also will be a challenge, because the stack is located on the removable superstructure, and OF COURSE, the exhaust has to be routed via the stack.
Challenges galore, will take some time, I'm sure.
But for now, I have to clean house, tomorrow another week on a REAL tugboat... :D
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Oh that is looking good, and a great little engine, looking forward to sea trails :-))
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Thanks, Phil!
I am slowly starting to get good hopes on a succesful outcome.
Still a LOT of issues to solve, but at least I know now, that the engine will start...
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Great project, will follow!
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Today again a bit of "mechanics" instead of "shipbuilding"... Wouters main engine needs to be installed, but that involves quite a bit, and what's more, there's also some work to be done on that machine first: One of the things that "bothered" me a bit about the design, was the fact that the cylinder head is not only "completely uncooled" (no cooling water flows through it) but also rests on a non-metallic gasket.
I see two problems with that: firstly, such a gasket will burn away slowly sooner or later, secondly, it forms a heat barrier. The heat is dissipated (it has to, because the temperature eventually stabilizes), but because of that barrier, the temperature of that head is quite high. Up until now, that engine has only run "unloaded", but soon it will of course have to deliver power, and then I don't like that, because replacing such a gasket is difficult, and those high temperatures can lead to warping. A buddy of mine, who is VERY handy with metal, CNC milled a gasket out of aluminum for me.
The idea is to anneal that aluminum plate so that it becomes soft and hopefully seals well.
Of course, a very thin smear of Loctite is also added for good measure. This gives us a gasket that is less sensitive to burning away, and the heat from the head can escape better.
Another advantage is HOPEFULLY, that this gasket will come off undamaged if necessary, because that is the other disadvantage of non-metallic: it "bakes" and does not come off undamaged. Cleaning the gasket surfaces is of course VERY critical, you don't want any scratches here.(https://www.modelbouwforum.nl/attachments/20250130_091724-1-jpg.608393/)
Of course, this is a good opportunity to inspect the engine internally, and I was actually quite happy about that: Very little carbon on the pistons, the cylinders are greased on the inside, and no running marks on the linings.
(https://www.modelbouwforum.nl/attachments/20250130_091647-1-jpg.608391/)
The head showed some carbon on the exhaust valves, I think that is partly due to the experiment with the oil line above the rocker arms (which has already been closed off by the way).
(https://www.modelbouwforum.nl/attachments/20250130_091700-1-jpg.608392/)
Furthermore, the "cam trough" (actually a misnomer, this is where the cam followers and push rods are located) also looked fantastic.
(https://www.modelbouwforum.nl/attachments/20250130_091746-1-jpg.608394/)
I am VERY pleased with how the engine looks on the inside, although in all honesty I have to say that the machine has only been running for about 4 hours, and in fact completely unloaded. The times that it ran under load were just with my finger against the flywheel, so relatively short-lived. I am starting to become more and more optimistic in that respect. Now first the new gasket has to be made to fit (one hole still has to be made, which my mate forgot to mill), annealed, and mounted.
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Can't wait to see this project on the water,
... got my wetsuit and Skis ready to go ! {-)
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And of course, I messed up the annealing of the headgasket (overheated, slight deforming), but with a bit of luck it is still usable.
What is worse is that when tightening down the head, it felt as if a few of the threaded holes for the head bolts felt like they were giving in.
Scary...
Later today, an attempt at running, to see if everything still is allright.
If the threaded holes indeed have collapsed, I still have the option to glue in a few studs with Belzona 1111, but that's a last resort... Dammit.
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Well... A bummer.Not a disaster, but a bummer.
I can't get that metallic gasket to close, and so close that I can't get the engine to start because of no compression.
So I HAD a well-running engine, and now it doesn't for a while, because...
The fact that the aluminum gasket went wrong is a shame but not insurmountable. Then we'll just go back to the non-metallic gasket What's more annoying is a combination of circumstances: The cylinder head is attached with 10 M2.5 screws, strong enough in themselves (looks a lot like material quality 12.9 but I don't know, because they're Chinese, right?) and they are in threaded holes in the cylinder block. Unfortunately, those threaded holes are 8 mm deep, the cylinder head is exactly 10 mm thick, but they opted for bolts with a thread length of 13.5 mm. So the last part of the thread of three or possibly four holes has become overloaded... Shite!
The original design was 17.5 cc, but this version is a whopping 20.5 cc, which means there is no meat left in the cylinder block to drill out and go to M3, OR to put a helicoil (which I don't think exist in this size anyway). There are two options, longer bolts, or glueing threaded rods into the block with Belzona 1111. The latter option will be very difficult, because there is actually no room for nuts. So I would have to try to create space in several places, including UNDER the bearing blocks of the rocker shafts. So first try the longest possible bolts that will fit.
They have already been ordered, with a bit of luck they will be delivered tomorrow, but I'm afraid not, it will probably be Saturday... :(
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Can't wait to see this project on the water,
... got my wetsuit and Skis ready to go ! {-)
Patience, Martin... It's gonna be a while, I'm afraid...
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Your tenacity its an example to us all
Bon Courage :-))
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I am still convinced, this contraption somehow, someway, WILL be operational.
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We undeterred continue with the "installation", fully expecting that I will get the engine running again with the longer headbolts and the paper gasket. Of course, if you want an engine to run at a regular speed, you need some kind of regulation, and that starts with a throttle servo. I didn't make it very easy for myself, because the simple carburetor that was originally on it was rather awkwardly placed, but at least it still had a throttle lever. I replaced that carb with a slide carb from a Force .15 car engine, because it has a bit more "mixture regulation", AND a plastic insulation sheath on the neck.But those things don't have a throttle lever, which makes the control even more difficult. Add to that the fact that the needles of such a carb are also relatively unfavourably placed, and that again limits the options for turning the carburetor to a favourable angle.
It is what it is, and this is what it has become: (https://www.modelbouwforum.nl/attachments/20250201_093638-1-jpg.608589/) The servo is in line with the linear movement of the throttle valve, and (https://www.modelbouwforum.nl/attachments/20250201_093659-1-jpg.608590/)The controlrod will clear flywheel, driveline and exhaust system. Next step: RPM detection...
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Happy to report, that the engine survived the operation. The goal (metallic headgasket) remained unachieved, but the engine survived and has been run in the meantime.
https://www.youtube.com/watch?v=kNUmQaStzGI (https://www.youtube.com/watch?v=kNUmQaStzGI)
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Great to see it running!
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State of affairs:
(https://www.modelbouwforum.nl/attachments/20250202_224537-1-jpg.608857/)
A beautiful lightweightcarbon throtttle control rod (for that all important lightningfast throttle response {-) ) and the RPM sensor has been installed too.
This sensor is not the original supplied with the Futaba GV1 governor, which needs a pulse magnet, because I did not want to drill up the flywheel, causing a possible unbalance. Instead, I am using a special Hall sensor that functions as a proximity switch (for those interested, a Melexis MLX90217), which detects the 6 boltheads that hold the outputshaft to the flywheel.
These sensors are pretty tiny, about 3 x 3 x 1,5 mm. It needs a 10K pull-up resistor over + and ~ connections to function, and my soldering skills are as far as electronics and tiny components go, mediocre at best. But even that went over fairly uneventful. No blistered fingers, no half-burnt components.
Tomorrow setting up the governor and TX, and a testrun to see if the governor functions properly, and then it is time to start installing the engine and building up the "surroundings" (cooling system, fuel system, exhaust system, controls).
Slow process, most time is spent thinking about how to make it all fit spacially. Cooling water expansion tank has to be higher than the engine, fuel tank has to be level with the carb, Exhaust needs to be a little lower, but not so low that the oil residue cannot be drained out (The exhaust contains a bit of oily residue, and that residue leaving the stack is an absolute no-no, things like that have all to be considered), so it is 5 hours "thinkering" for every 5 minutes of tinkering...
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Completely to be expected because the governor is not made for boat applications,the first test with the governor failed.
https://www.youtube.com/watch?v=99MqQLXUBCM
Of course these things do not work at first try, I spent months getting the governor of my other little gasoline boat (https://www.modelboatmayhem.co.uk/forum/index.php/topic,69665.0.html) functioning properly.
Trouble is, basically, that it was about 10 years ago when I did that, and the settings menu in the governor, Futaba never published any documentation about that. Back then it was a total matter of trial and error, I will have to retrieve that from reading back in very old forum topics.
Also: apparently, my earlier measurements of lowest RPM were a bit off, at least, the governor display won't drop below 1300... That's a bit of a bummer, but still workable and within the RPM limit of the propeller...
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Tiny change of plans...
For now I am going to ditch the governor, and go with the simple makeshift, a throttle curve. This, because contrary to the single cylinder in the little launch, which shows virtually zero tendency for RPM stability, this fourcylinder, if I set it at throttle position X, it runs all day at a constant RPM.
Which should mean, that a simple throttle curve connected to the pitch control, should be sufficient, after all, I have flown helicopers with that set-up for the better part of 30 years.
Which means I have meanwhile started installing the engine.
(https://www.modelbouwforum.nl/attachments/20250203_184226-jpg.608916/)
Pitch servo has been installed. The servo mount has to be sturdy, since the required actuating force is pretty high.
(https://www.modelbouwforum.nl/attachments/20250203_184245-jpg.608917/)
The engine is in place, and bolted down this time... I expect it to stay there for a while...
(https://www.modelbouwforum.nl/attachments/20250203_184253-jpg.608918/)
The cold end of the bilge cooler tubes is connected to the inlet of the oil cooler, from where it passes on top the suction side of the cooling pump.
(https://www.modelbouwforum.nl/attachments/20250203_185528-jpg.608919/)
The hot end of the bilge cooler tubes has the supply line from the expansion tank, but the expansion tank itself has not yet been installed.
Fuel tank, expansion tank, that kind of stuff all has to wait until next week.
As can be seen in the pics, I have also fitted about 5,5 kilograms of lead in the sides.
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Dammit! It HAS been in the water, WITH a running engine.... And then the boat itself reminded me of that one grubscrew left un-loctited...
Runtime has been too short to judge the effectiveness of the bilge coolers.
The contraption has been fixed, waiting for the loctite to cure, report back in about half an hour...
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Cursed! Again... I was very sure that the other part of the cardanic coupling was secured with loctite, but now this one is loose, and that is, to be honest, going to be problematic, because it is the layshaft side, meaning the cardanic for now stays in the hull, loctited to the propshaft...
>:-o >:-o >:-o
BUT... on a positive note, it DID hold for a few minutes, so I got to see the prop churning water. Wow, that has some giddyupgo in it...
I also got time to judge cooling, at least with idling engine and no waterflow around the cooling tubes.
I saw an engine outlet temperature stabilizing at about 55 deg C, which is a whopping 15 degrees lower than the aircooled radiator for this engine.
And that's with the boat stationary... I expect the cooling effect to improve when running through the water.
All in all, I am not dissatisfied.
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Meanwhile, the drive shaft has been repaired and improved, but not yet tested.
An issue that was still to be solved, was to enlarge the rudder, AND modify it such that it becomes easily removable.
This is a necessity because the pitch propeller needs relatively frequent regreasing via a grease nipple in the back of the prop hub.
The rudder the hull came with, had a throughgoing rudder kingpin all the way down to the heel. To pull the rudder, it needed to be lifted a bit, after which the bottom of the kingpin could be pried sideways, and the entire rudder assembly forced downwards. That took quite a bit of force, and the rudder arm had to be removed every time, making readjustment of neutral position a repeated necessity. I was afraid sooner or later something would get damaged.
The idea was to fabricate a rudder kingpin with a clevis holding the rudder blade. The rudder blade will rest in the heel on a short stump, and the clevis on top butting against the rudder tube will prevent the stud at the bottom of the rudder lifting out of its pocket.
This is what I came up with:
(https://www.modelbouwforum.nl/attachments/20250213_144443-jpg.609838/)
Bolts removed, due to the bottom stud being very short, the rudder can easily be tilted out
(https://www.modelbouwforum.nl/attachments/20250213_144652-jpg.609839/)
and the rudder lifted out
(https://www.modelbouwforum.nl/attachments/20250213_144705-jpg.609840/)
The bolt holes in the rudder are (not yet on the pics, but meanwhile) fitted with brass tubing glued in, so the holes in the wood will not ream out by the screws or the steering forces, and also to prevent water from soaking the wood.
Of course, the rudder WILL be painted and sealed.
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Every day a bit more progress... Things start to function... a bit better than the day before
https://www.youtube.com/watch?v=kiRjcK16TYI
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Every day a bit more progress... Things start to function... a bit better than the day before
I wish that description could apply to many of us on here! Keep up the good work.
Colin
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A wise and clever Chief Engineer I worked with over the years, back when I still was not one of those, had that as his motivational morning speech: "If at the end of today, we're a little bit better off than the day before, today will have been a good day".
I have taken that as a life-slogan, trying to live up to it, not always that succesful though... {-) {-) {-)
But today I managed to give the ignition a decent place in the boat.
(https://www.modelbouwforum.nl/attachments/20250214_131931-jpg.609928/)
Hope to also fit the starting electrics.
Still plenty to do...
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For one reason or another, I never stick to "the plan"...
I was going to focus on the electrics of the starting system. Not so much the system itself (that's a ready made item that came with the engine support parts kit, the "starting kit", that contains the ignition system, a radiator and electric cooling fan, and the pre-wired starting relay and switch), but more exact the installation of that system, including the actuating servo, somewhere in the boat.
But nope, you can't force "inspiration", what kept droning through my head was "cooling system... You've GOT to do the cooling system"... So I did.
(https://www.modelbouwforum.nl/attachments/20250214_203302-jpg.609976/)
A tank support, expansion tank with approx 100 ml of cooling liquid, a suction line from tank to bilge cooling tubes, and a return line from engine to tank.
The bilge tubes, as well as the connection to oil cooler, pump and cylinderblock were allready done at an earlier stage.
As it is, this system is functional, but what still needs to be done at a later stage is a temperature sensor in the returnline, and a servo-operated bypass valve over the bilge cooling tubes, to send part of the water as required, uncooled back to the engine.
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Well.... Crap!
I was hoping to be able to do an inwater test today, but when attempting to fabricate the threstle forthe fuel tank, my tiny hands still were too large, and I knocked the support for the expansion tank loose.
That goo that the builder used to waterproof the hull internally, I don't know what is wrong with that crap, but it somehow never cured properly apparently, and it caused a weak glue joint.
So I first had to figure out how to clean that crap off the hull frames, in order to re-glue. With Bison Kombi Power this time. Hopefully this time it will hold better.
Because of that the support for the ful tank had to be postponed, so I continued with the starting arrangement.
At least, that now works from the TX, so remote starting is an option.
I did however, find in my crap-boxes a small car-type muffler that should be able to handle the volume of exhaust gas, and of convinient size and with convenient stump locations.
So all in all, still living up to the motto: every day a little bit better than the day before.
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https://www.youtube.com/shorts/B-1DDHUXVjs
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poop AND DISASTER!
Words fail me to dscribe my current emotional state...
First start this morning, boat in the water, THE PROP FAILED INTERNALLY...
As far as I can tell, the driveshaft transfers both pitch control movement, as well as driving torque, via a square block in the prop hub, attached at the end of the drive shaft.
It has all appearance, that this block disconnected from the shaft the first time I actually tried to move pitch with running engine.
I started the engine with pitch in neutral, carefully adjusted pitch to "absolute" neutral and tried giving a little bit astern and ahead. The boat responded to astern, jerked forward when I gave it the slightest bit of ahead, then basically lost all drive, apart from a very low RPM at the prop due to residual friction.
The hairpulling thing is that EVERYTHING ELSE works: Cooling system, fuel feed, starting system, throttle and rudder control... Even the exhaustgasses exiting the boat via the (rather characteristic shaped) funnel works beautifully...
Also, the sound is beautiful, extremely realistic, originating from the funnel, there is not a lot of mechanical noise...
Here's all I can show you, but this is from after the prop failed:
https://www.youtube.com/watch?v=DX2nxHbRj20 (https://www.youtube.com/watch?v=DX2nxHbRj20)
Tomorrow I am going to call Raboesch, to see if there is still anything that can be done... But from what I gathered during an earlier phone conversation I had with the guy that actually made thse props years ago, IF possible, it is going to be a very costly affair...
I am VER bummed out right now...
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This morning I had a talk with Raboesch Models, the maker of this prop.
With some advise over telephone, I pulled the prop off, and since Raboesch is located approx 100 km from whre I live, a quick drive and I delivered it to them.
Since this particular prop turned out to be VERY old (one of the first designs, probably made about 40 years ago) they were not 100% sure but they were going to try to fabricate a new pitch yoke and shaft according to the later, improved design.
In the old design, the one I have, a single 1,5 mm pin was the only connection between pitch yoke and shaft.
In the later design, cross-axial slots are milled in the shaft on four sides, and pins are inserted in holes in the yoke, locking in the shaft all around, which has a much higher allowable torque load, and the yoke stability is much better, reducing friction when adjusting pitch.
So it's a bit of a stressful situation right now, since there is good hope, but not 100% certainty.
Here are some pics...
The prop, pulled from the shaft:
(https://www.modelbouwforum.nl/attachments/img-20250217-wa0002-jpg.610249/)
the shaft end, that is in the pitch yoke, the sheared locking pin visible:
(https://www.modelbouwforum.nl/attachments/img-20250217-wa0004-jpg.610250/)
The flange at the end of the tunnel:
(https://www.modelbouwforum.nl/attachments/20250217_145601-jpg.610251/)
(https://www.modelbouwforum.nl/attachments/20250217_145607-jpg.610252/)
Now they are extremely busy over there at Raboesch, flu outbreak so a lot of people with sickleave but with a bit of luck, I will have th prop back in about a month.
Since the repair is skilled labou and a "one-off" handwork, I am told to expect a repair price of around €250 or therabout, which is of course quite a bit, but it is either shelling out, or the project can be scrapped...
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Looks like rather a weak link in the drive. I have an old vp prop made by Rivabo that I used in a Culamix steam tug powered by a Stuart Turner 10V. This used a square block on the end of the shaft and the shaft was moved back and forwards to vary the pitch. The block was threaded onto the shaft giving a much more secure link, as the shaft only turned in one direction it could never unscrew in use.
The 10V on 60 psi had plenty of power, the tug would tow a full size rowing boat with a passenger.
Jim
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It IS a very weak link, and for the life of me I cannot think why they did it like that. EDIT: But that they did not use a screw connection was due to the fact that both directions of rotation were availlable.
Rivabo, the name rings familiar, but I can't remember whether they built variable pitc props. If they did, I was still a kid back then...
I am aiming for the same kind of power, and I have a small hope that I can achieve about 3 kilo of pull IF the engine will pull the large diameter blades.
To come back to that "weak link", it turns out, that my prop was one of the very first designs, probably about 40 years old. The current boss of Raboesch, who in his younger days was involved in the handywork of those variable props, did not recognize its design.
I'll try to make a drawing of the later Raboesch design for the yoke attachment to the shaft. It's pretty cleverly designed and should in theory be "unbreakable". It was back then a very difficult to manufacture design (faillure percentages in the machining process, which all was done manually, about 30%), but he told me, nowadays they can achieve a much better accuracy with near zero machining faillure, using CNC controlled spark erosion.
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I'll try to make a drawing of the later Raboesch design for the yoke attachment to the shaft. It's pretty cleverly designed and should in theory be "unbreakable". It was back then a very difficult to manufacture design (faillure percentages in the machining process, which all was done manually, about 30%), but he told me, nowadays they can achieve a much better accuracy with near zero machining faillure, using CNC controlled spark erosion.
(https://www.modelbouwforum.nl/attachments/20250218_102412-jpg.610293/)
This is that design: four recesses are cut in the shaft, and four tangentially placed holes drilled in the yoke. The hardened pins are placed with Loctite, and the connection between shaft and yoke should theoretically be as strong as the shaft itself.
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The newer design looks to be more secure. I probabbly bought the Rivabo vp prop around 40 years ago to replace the reversing gear setup I had originally made for the tug. This worked ok but with straight cut steel gears it was noisy and gave a loud clunk every time iit changed from forwards to reverse or back, there was also no proper neutral position so the boat couldn't be stopped.
Jim
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I had no option for a reversing gearbox, for reasons that I would then end up with a boat that would have a fairly high minimum speed due to the fact that there is a limit to how slow an internal combustion engine at this size can run, and of course gear reductions can lower that minimum speed, but then higher speeds or stump pulling bollard pull would make the boat sound like a Formula One car, and that would totally ruin "the experience"...
And without that, this boat would have nothing going for it...
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The newer design looks to be more secure. I probabbly bought the Rivabo vp prop around 40 years ago to replace the reversing gear setup I had originally made for the tug. This worked ok but with straight cut steel gears it was noisy and gave a loud clunk every time iit changed from forwards to reverse or back, there was also no proper neutral position so the boat couldn't be stopped.
Jim
By the way, and just out of curiosity WRT longevity of such mechanisms... Is that tug still active or at least that prop still in operattional condition?
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I'me afraid the tug has not been active for many years, it was rather large and awkward to carry on a motorbike so has been lying in the workshop for quite a while. The steam plant has been out of action as it doesn't have a boiler certificate so I can't run it. It was fully hydraulicaly and steam tested after I made it but there was no one at the club who could officially test it for a certificate.As far as I know the prop is still working OK although I have not looked at it for some time. It probably had around 5 to 10 hours running in total over the time I used it.
Jim
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It probably had around 5 to 10 hours running in total over the time I used it.
:D :D :D I probably go through that in one, maybe 2 months... :D :D :D
Bummer about that testing you guys have...
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Is the basic problem that the gasoline engine is simply putting too much stress on the mechanism? Would an electric motor have worked better. Maybe the gasoline engine really needs a more robust gearbox/clutch mechanism rather than relying upon the built in variable prop components which were probably never designed to accept a motor of that type.
Colin
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Is the basic problem that the gasoline engine is simply putting too much stress on the mechanism? Would an electric motor have worked better. Maybe the gasoline engine really needs a more robust gearbox/clutch mechanism rather than relying upon the built in variable prop components which were probably never designed to accept a motor of that type.
Colin
these props are advertised as suitable for steam engines. A twin double acting compound runs quite a bit chunkier than this fourcylinder I am using, which runs remarkably vibration-free, also in the torsional sense.
But as stated, the prop I have, appears to be of a really old design from Raboesch, which was extremely flawed. In hindsight, now that I know how it was constructed, I could have twisted this locking pin basically by hand allready.
The tiny 5 cc single cylinder runs quite a bit rougher judging by the rocking action of the boat when in neutral, and that prop is made of 40 year old plastic.
According to the current owner of Raboesch, who worked in production during the last years of production of these props, there was zero doubt that these props should be able to handle any type of powerplant that would be capable of running it at 4K. But he was NOT aware of this old design.
So it stands to reason that once modified to the new design, it should hold as long as I make sure it never exceeds 4K, which should not be very complicated since I still intend to use a governor.
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A few cosmetic changes:
The wheelhouse windows were a horrible orange colour (can't imagine why anyone would want to do THAT...) and are replaced for clear glass.
(https://www.modelbouwforum.nl/attachments/img-20250219-wa0011-jpeg.610384/)
And the slide hatch on the rear deckhouse was a horribly poor fitting ugly piece of black plastic, now a proper wooden hatch. It only needs some darker colour (woodstaining or something) and a coat of laquer.
(https://www.modelbouwforum.nl/attachments/img-20250219-wa0013-jpeg.610385/)
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Telemetry for the coolingwater temperature is installed. This sensor is ALSO going to control the servo that opens or closes the bypass over the cooler.
(https://www.modelbouwforum.nl/attachments/20250220_145152-jpg.610515/)
For temperature control, this location is less ideal: rapid loadchanges will show rapid temperature changes, and that tends to lead to a valve overcontrolling.
A sensor in the expansion tank would be better.
But IF the coolingwater pump drivebelt snaps, the temperature of the expansion tank will not change, but this location will se virtually immediately steam, AKA a very rapid jump in temperature to 100 deg C.
On the other hand: I have two temperature channels availlable, I could fit a second sensor on the outlet of the xpansion tank, and use one for alarm, the other for control.
More work, but perhaps worth it. Not sure yet. Going to test without control first anyway, just to see where temperatures end up.
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And THIS:
(https://www.modelbouwforum.nl/attachments/20250220_170834-jpg.610535/)
(https://www.modelbouwforum.nl/attachments/20250220_170850-jpg.610536/)
is how you make a variable throttle, otherwise known as a controlvalve, with the bare minimum in materials, tooling and cost.
I will be using this as a variable bypass on the bilge-coolers, in order to control engine temperature, IF necessary.
:-))
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Talked to Hanco (owner of Raboesch) this morning, the guy that was to make the shaft reported sick this morning, but with a bit of luck, I will have my prop back somewhere in the coming week.
Fingers crossed...
So now out with the old Ducati to work on its electrics (and no, I know their reputation, but this 38 year old bike does not have issues, it's an upgrade to LED headlight that I started a few weeks back and still have to finish).
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Darned flu epidemic is keeping me from getting my prop back... >:-o >:-o >:-o
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YESSSS!!!!!
Just got news from Raboesch, my prop has been repaired.
Cost me an arm and a leg, but who cares?
Only frustrating thing right now is that I just yesterday began another 2 week shift on board, and by the time I get back (9th of April, Raboesch is closed for almost a week... Dammit!
But in 3 weeks, I'll be fitting back that darned prop!
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And TRIPLE YESSS!!!
I have my prop back, and it appears to be a solid repair.
(https://www.modelbouwforum.nl/attachments/20250416_140844-1-jpg.615618/)
This was the culprit..
(https://www.modelbouwforum.nl/attachments/20250416_141010-1-jpg.615619/)
This USED to be one single pin, only 1,5 mm diameter, which couldn't cut it therefore it got cut...
The small boss at the forward end of the prophub has a press fit in the sterntube, and I did not, of course, want to mess with this fit, so I had to figure out a way to get it in the tube with as little friction as possible.
So the shaft and hub went into the freezer at -20 deg C for half an hour, and I had to devise a way of heating the tube without damaging the Epoxy that holds it in the hull.
(https://www.modelbouwforum.nl/attachments/20250416_152828-1-jpg.615628/)
The tube is 8 mm inner diameter, so I took an old drillshank and iserted it in the tube, resting a plugged in 75W soldering iron on the drill.
This turned out to provide gentle heating, it took about 40 minutes toi reach 50~60ish degrees C.
The shaft being so cold that when I applied an anaerobic sealant on it, that sealant basically froze, but it allowed for simply pushing the hub home, where within 5 seconds it locked in place.
I am pretty sure, this will hold until the next time I need to get it off. Which hopefully is never.
There is about 2 hours of tool-time in it to reconnect everything, adjust and check, cure the threadlocks (I use Loxeal 85-21, pretty strong stuff).
With a bit of luck, There will be a bathtub testing session this evening, and if so, possibly tomorrow (weather permitting) a careful maiden.
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With a bit of luck, There will be a bathtub testing session this evening, and if so, possibly tomorrow (weather permitting) a careful maiden.
:D :D :D
Still FAR from p[erfect, and a long way to go...
https://www.youtube.com/watch?v=XsUOplituBA
And VERY promising:
https://www.youtube.com/watch?v=FyKuIq1pNKA
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Anyone wondering where the pics went, the forum they are hosted on, is currently under maintenance, and they should reappear later today.
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Meanwhile, while still quite a way to go, At least I am getting some control over the mixture under load changes.
Ithis is achieved by placing an orifice in the airfilter, restricting airflow just a tiny bit, just enough to generate a slight underpressure at the air intake when the throttle is opened. This tends to linearize fuel draw through a single metering valve, more in line with the increase in air consumption.
It is a bit of a "bandaid solution" but it did work well in my earlier single cylinder boat.
First vid, it was still a bit too rich, hence cutting short the test.
https://www.youtube.com/watch?v=TpzFsvcesJM
But there definitely was improvement in the engine not shutting down, so a touch leaner and...
https://www.youtube.com/watch?v=uZ2tDX4aUIk
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Still a lot of work to be done, but the maiden voyage was all in all a resounding succes!
in total maybe 35~40 minutes of runtime, the first 25~30 were non-stop to see if the engine kept running reliably.
It did... It kept running without any serious issues, and I had to shut it down to get it to stop. Which I did, and restarted, etc etc. Working brilliantly!
The superstructure, it turns out the boat fills with exhaust gas, and the engine increasingly started to labour and lose power.
So most of the testing was done without superstructure, but here it is:
https://www.youtube.com/watch?v=EWfugslE3_8
She is quite fast, although I do not have that on video, she easily exceeds "hull-speed", and I haven't yet pushed her to the limit.
https://www.youtube.com/watch?v=cF-NWFQT-Xg
Bollardpull was tested, not measured, I wanted to know first if the boat would be controllable under tow, and she is.
It FELT like approximately 1 kilo, not even at full power, but the prop pulls airt too easily, it needs ballast.
https://www.youtube.com/shorts/hLom8fwTScc
If I had to estimate, there could be between 1,5 and 2 kilo of bollardpull, but that remains to be seen, also because there still is a lot of work to be done getting the combination between prop-pitch and throttle functioning.
The cooling, it HAS to be luck, was "goldilocks".... Júst right....
Free running, I saw between 68 and 74 degrees and during the bollard pull test, about 1,5 minute in, I saw 79 degrees Celsius.
I am an extremely happy chappy...
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Meanwhile, no posts did not mean I did not do anything...
As stated in previous post, the superstructure apparently affected how the engine was running, within 10 minutes from start during the maiden test, engine seemed to struggle, which as by flicking a switch dissapeared when running the open boat.
Initially, I thought it was exhaust gas leakage internally displacing oxygen and suffocating the engine. This suspicion was supported when I found the pressure tap of the Notro car muffler had come loose.
So yesterday, I tested with the repaired exhaust. The engine held out longer (approx 18 minutes, but then it started to bog down again. What was more remarkable, after running the boat 5 minutes without the superstructure, I placed it back and the engine bogged down within 2 minutes/ This made me think, heat could also have to do with it.
After all, there is an engine block at 70 degrees radiating heat, there is a 100 ml expansion tankof the same temperature radiating heat, and there is an exhaust muffler of maybe 150~200 deg C. And the only ventilation would be the engine drawing its air from inside the boat.
I still had the 62 mm electric cooling fan that came with the Engines accessory kit, and I decided to install that above the engine, blowing down at the carb area, but in general ventilating the entire boat at a decent rate (I have no fan data, but if I had to guess, something like a full airchange every minute or so)
I decided to place the fan in the superstructure, and feed it from the starting battery. That would allow me to camouflage the intake as an open Engine Room skylight.
Since the fan turns out to consume only about 400 mA, and the starting battery is a 2500 mAh 3S LiPo, that should result in PLENTY capacity to be able to runthe fan basically all day and still start towards the end of the day.
(https://www.modelbouwforum.nl/attachments/img-20250420-wa0003-1-jpeg.615746/)
opening the skylight hatches... I did not yet know if I would need one or two, but one was sufficient in the end.
(https://www.modelbouwforum.nl/attachments/img-20250420-wa0001-1-jpeg.615749/)
Constructing an airduct/fan base
(https://www.modelbouwforum.nl/attachments/20250420_195116-1-jpg.615794/)
The open skylight...
(https://www.modelbouwforum.nl/attachments/20250421_113114-1-jpg.615850/)
the fan, installed under its airduct, in the superstructure
Off I went testing. Started the boat, placed the superstructure from the get-go, and for 22 minutes I had a very consistent engine behaviour, when the pitch control linkage malfunctioned at half ahead, which forced me to bring the boat in, shut down the engine and take it out of the water.
This turned out to be just a linkage pin that had worked itself loose, and that was a 2 minute fix.
Boat back into the water, and off we went again. another rather uneventful 41 minutes later, I was wondering how long the fuel (normal filling capacity approx 250 ml) would last, because I noticed the engine leaning out a bit.
Bringing the boat in, there was about 50 ml of fuel left. Not bad.
So we have the following figured: Fuel capacity appr 250 ml., consumption appr 200 ml/hr, theoretical 75 minutes endurance.
Ignition current draw 200 mA, Ignition battery 1000 mAh, theoretical endurance (taking max allowable depletion of LiPo into account) of 4 hours
Fan current draw 400 mAh. battery 2500 mAh, so theoretical endurance until max depletion 5 hrs
Starting current is 2 sec bursts of 12 A, the equivalent of 7 mAh per start, so that does not do much
RX/servo consumption still to be determined, will edit in later, but estimated around 600 mA average, expected runtime about 3 hrs. EDIT: 1 hr of running the boat resulted in a recharge of 635 mAh for a 2000 mAh RX battery. So there is roughly 3 hours of operating time there as well.
All in all a boat very usable for demo days and such.
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Just hit a snag... >:-o
(https://www.modelbouwforum.nl/attachments/20250422_091450-1-jpg.615897/)
This is the cup of the engine side dogbone coupler, and it has wallowed out severely.
This limits the fore/aft movement of the shaft considerably, as well as that it transfers axial loads on the crankshaft.
Big bummer.
Going to ask a friend to make me a cup from hardened steel.
Also going to try and fabricate damper rubbers in the drivetrain, apparently the torque is not as constant as it seemed when the engine was on the testbench.
No idea yet how to do that (making a torsional damper, I mean).
Crap!
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Abstract art...?
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How about ....
(https://i.postimg.cc/1V1Z3Wtr/Screenshot-2025-04-22-092956.jpg) (https://postimg.cc/1V1Z3Wtr)
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How about ....
(https://i.postimg.cc/1V1Z3Wtr/Screenshot-2025-04-22-092956.jpg) (https://postimg.cc/1V1Z3Wtr)
The shaft travels some 5~6 mm in forward/aft direction when pitch is being adjusted, and there is a very shallow angle (less than 5 degrees). The dogbone coupler was the one supplied with the prop when I bought it, so I was hoping it could handle it. My hope was in vain.
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True.... why do the must hopeful wrong paths take so long to be discovered !
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or .... https://www.ebay.com/itm/355588326442
or .... eBay item number:355367341102
(https://i.postimg.cc/MTyNvsyC/Coupling.jpg)
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That is one of the great questions of life...
And unfortunately, the "why" will never be explained. All we can do is walk along ALL hopeful wrong paths until we have the one that is not wrong...
I know about these telescopic shafts. There is one downside, they are to the best of my knowledge not availlable in the length that I need... Otherwise I would have ordered one long ago.
What I need is one that has a safe extendable length under load of 24 cm.
I have not yet seen them longer than 22 cm...
They are usually intended for Crawlers, so probably not that suitable for heavy loads.
Which is a real shame, since these splines look like they would slide excellently under load...
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A friend of mine made a copy of the coupling=cup out of hardened tool steel.
This evening I took the boat out for nearly to the minute exact 1 hour of sailing (I believe the runhour counter said 1 hr 1 minute). Where the brass cup severely worn away in less than 2 hours, the new cup did not show ANY detectable wear or wallowing-out after this hour.
Of course, pitch, now not being hindered by those horrible notches, responded quite a bit better (but still needs some work to improve controllability, because there's quite a bit of hysteresis) and all in all, I just had a nice evening of absolutely troublefree operation.
Engine started immediately, kept running, and seems to run better every outing...
The warm weather of the last few days was noticable in that in general the entire system consistently ran 2~3 degrees hotter than 2 weeks ago. It means that probably I need to increase cooling capacity a bit/ Most likely I will simply replace the existing 3 mm ID tubes for 4 mm ID. That will increase effective surface by about 30%, and dwell time (time the water spends in those cooling tubes, dissipating heat) by about 75%.
The cooling fan works wonders, and all in all, I am happy with the set-up.
https://www.youtube.com/watch?v=apmv7IJsEKM
https://www.youtube.com/watch?v=_6-f_VWYC54
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The engine by now has about 4 hr 20 minutes of "in-water" runtime.
I kept myself busy with tryihg to get the governor to work, but 3 things stood in the way. ome down, 2 to go.
One issue was that the throttle servo mount was rather flexible. this hs severe impact on precision of control. THat has been fixed.
Did not solve the governor issues.
on the to-do list are stil the issue of carburation, on this scale and for this purpose and fuel type, there simply are NO suitable carbs availlable. That is going to be a real chore.
The last thing is that this governor is very fast, and difficult to "tame".
The idea is, that I will fit a servo-slowdown in order to make it move so slow that the engine will follow without overshooting.
BUT...
In the meantime I got myself a digital dynamometer, and with that I managed to measure bollard pull.
She pulls in current shape and form about 1,9 kilo, and that is by all standards quite impressive...
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After some consideration, I have decided to try a reduction gear for the following reason:
The more RPM the prop turns, the more difficult the pitch adjusting mechanism moves, due to the centrifugal forces acting on the blade roots.
The engine won't run below approx 1500 RPM, and this RPM allready makes the pitch mechanism move "notchy".
Now if I could reduce that prop RPM, pitch will move more freely and controllability of the boat improves.'
Since I have basically 100% freedom of programming in the Taranis, my thought was as follows: I can utilize the centre half of the stick movement for pitch control at minimum RPM, from neutral to max in both directions. This should allow for fine control of thrust, and thus a good manouverability.
At stickdeflection above half, I can hold pitch as fixed in max position, and start adding RPM.
The downside is a higher engine RPM when towing, taking away a bit of the sound and "feel" of the boat, but that is going to be used only when actually towing so probably less important.
I ordered a planetary gear, as that does not change the alignment of the shaftline.
The only suitable gearbox I could find (5 mm in, 5 mm out) has a reduction ratio of 1:3.7, meaning at idling engine (appr 1500 RPM) prop RPM will be appr 400 RPM.
I have no idea what kind of engine RPM will still be acceptable WRT sound, but probably 3000~3500 and that should result in around 800~950 on the prop.
With a bit of luck, I can use a higher max pitch value, so I should not loose too much static pull.
It's a long road, but slowly I'll be getting there...
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Slight delay, I thought I had placed a valid order for a gearbox, but somehow, payment never happened, so no gearbox yet...
With a bit of luck, 2 weeks from now...
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<:(
-
<:(
It gets worse, I repeatedly tried ordering yesterday, none of them "caught", and I am pretty bummed about that.
But the good news is, I also ordered NOT using PayPal but just my own banking service, and that one went through, even received a confirmation from AliExpress, so fingers crossed...
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Meanwhile, received confirmation that a reduction gear with my name on it, has left China...
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Still no gearbox... >>:-(
But a nice meeting in horrible hot weather (32 deg C), the boat functioning as flawless as the rather stubborn pitch control allowed, no engineroom temperature issues (ventilating the engineroom with 32 deg C outside air apparently still is sufficient), no signs of overheating (highest cooling water temp 81 deg after a few minutes dead in the water with running engine), and a first (not too heavy) tow...
All in all close to 55 minutes of runtime consuming about 150 ml of fuel.
Towing, due to the not yet perfect pitch control needs to be done a bit careful, but the towing bit seems to be in a very usable spot: straight line course stability is basically as good as it gets, wider turns under power (when the towing wire is pointing other than straight aft and excerts a listing force) not causing any issues either.
The other two boats (gas powered cabin boat and the steamer) also each did about 1 hr of runtime, also flawless.
All in all a very lovely day if it would not have been zo awfully hot. Pretty exhausted...
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A different 'Gasoline powered Tugboat' !
Seen about 20 years ago at Deans Marine ...
(https://i.postimg.cc/ht86nv9X/505186146-10225514842409728-1222023404631722636-n.jpg)
(https://i.postimg.cc/ZqVQ9QsZ/504378117-10225514843329751-8671661226950994427-n.jpg)
(https://i.postimg.cc/Jh1gz8qP/504658613-10225514842889740-301638179008152834-n.jpg)
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WOW! That looks metal built?
Judging by the greasenipple on that propshaft tunnel, the window wiper mechanism being used as a rudder actuator, and what looks like some sort of Briggs&Stratton-like stationary engine engine, that thing must be HUGE...
Would love to see more about that.
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Found one more photo.
Sorry, the photos are all I know about it ..... anyone else?
(https://www.modelboatmayhemimages.co.uk/images/2025/06/22/PetolTugboat-Gapoline-1.jpg) (https://www.modelboatmayhemimages.co.uk/image/16fR1)
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:o Damn! That's BIG....
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Good grief how much bigger will it be with the superstructure {-)
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Personally, I would not fit a superstructure.... I would fit a seat...
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Meanwhile....
my gearbox has arrived!
Nicely made item, servicable, nothing complicated, BUT... The pinion gear, which I ordered for 5 mm shaft diameter, seems to be a press fit item, it does not have a setting screw, which is pretty weird, because the construction of the box itself would offer PLENTY of room for that. But alas, it is what it is, beggars can't be choosers, it is 5 mm and that is what is important.
(https://www.modelbouwforum.nl/attachments/20250623_111521-1-jpg.621860/)
A bit of a downside is that the output shaft, which I believed ALSO to be 5 mm, isn't, it is 8 mm. No biggie, the coupler that I have offers sufficient material to allow it to be drilled out.
(https://www.modelbouwforum.nl/attachments/20250623_124624-1-jpg.621862/)
One other thing that needs to be tackled is the flywheel adapter plate, which needs to be turned down a bit, in order to offer sufficient reach to get the pinion into the ring of satellite gears.
(https://www.modelbouwforum.nl/attachments/20250623_124655-1-jpg.621863/)
The 5 mm sticky-outtie part needs to be a bit more sticky-outier, so I called my lathe-kwondo Sensei, we're gonna fix that this evening.
The nice thing about planetary gears, is that they have no lateral forces, and the gear engagement being symetrically divided over its circumference, they tend to be a bit self-centering, only requiring a mount that mainly needs to be able to handle the torque, and halfway decent centered.
So installing that gearbox only requires a reasonably light bulkhead with slotted boltholes.
It really should not be a too complicated installation. Wednessday the workweek starts again, only one week this turn, so next week it should maybe take me 2 or 3 days to get the installation fixed.
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At the end of the tinker-session of this evening:
(https://www.modelbouwforum.nl/attachments/20250623_222358-1-jpg.621919/)
The coupler has been fitted on the output shaft. Probably a tiny burr at the threaded hole for the grubscrew, it did not want to slide home despite the bore being reamed to dimension. But I did not want to tap it home with a hammer, because that could damage the ball bearing.
The pinion was heated to appr 100 deg C, while the flywheel-adapter was cooled to around freezing, and I applied LoXeal 85-21.
Despite the temperature difference it took considerable force to hammer the pinion home.
Too late for turning down the adapter now (lathes make considerable noise when it is quiet in the evening). That will be tomorrow morning, first order of the day, and the last thing before returning to work.
Next week I hope to finish the installation before the weekend.
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Planetary or epicyclic .... are they both the same thing?
What ratio? ( Edit "1:3.7" .... Doh! )
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Planetary or epicyclic .... are they both the same thing?
Yup, different name, same thing.
1:3,7 was the lowest ratio I could find with these shaft diametres. It is apparently pretty difficult to construct 1:3, and the only ones I could find with that ratio had 3,17 mm shafts.
For constructive reasons I needed a gearbox with the shafts in line with each other, because initially I installed the engine as a direct drive with a straight shaft line.
I could design a 2 stage 1:2 or such, that would have its shafts more or less in line, but I do not have the means to build it and I could not find anything suitable and ready-made on AliExpress.
It would also have been much less compact, and constructive precautions would be needed to prevent lateral forces on the crankshaft output end.
So I will have to accept a much lower prop RPM and possibly a lower bollard pull. Upside is much lower forces on the conrods and big ends.
One of the downsides of the rather high RPM in direct drive, aside from the notchy pitch control, is that in neutral, due to the blades being curved, the prop causes a rather strong water movement when stopped in the water. This not only generates a considerable propwalk (the boat turning to SB on the spot continuously) but it also greatly increases the tendency to cavitate when reverse is ordered.
A boat spinning clockwise when stopped, is no good when the towing wire is connected to a tow...
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The last operations this leave period, in a week we can continue, but for now,,,
I had THIS:
(https://www.modelbouwforum.nl/attachments/20250623_124655-1-jpg.621924/)
but this would not provide the reach to allow the pinion to engage with the (I learned a new word :-)) ) epicyclic gears.
So I fired up the trusty old Ferm piece of crap masquerading as a lathe, and ended up with this:
(https://www.modelbouwforum.nl/attachments/20250624_091807-1-jpg.621925/)
The hub was turned down from 30 mm to 13 mm, over a lenght of 6 mm, so now this is possible:
(https://www.modelbouwforum.nl/attachments/20250624_091822-1-jpg.621926/)
Now off to work tomorrow, and I'll see you guys with more updates next week after Wednessday.
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Burt....considering their size and actual loading, what type of grease lubrication is recommended for these speed reducers?........
From an earlier image, the speed reducer appears to have a ZZ [metal shield] for the output shaft bearing, which is interesting. I would have thought LLU [plastic shields] would have been chosen due to cost minimization??
Looking forward to hearing in the improvements in propeller pitch control from this modification
Derek
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Burt....considering their size and actual loading, what type of grease lubrication is recommended for these speed reducers?........
From an earlier image, the speed reducer appears to have a ZZ [metal shield] for the output shaft bearing, which is interesting. I would have thought LLU [plastic shields] would have been chosen due to cost minimization??
Looking forward to hearing in the improvements in propeller pitch control from this modification
Derek
Given the size, load and expected speeds (I intend to keep RPM at or below 3K for the engine, MAYBE 4K, and I doubt power will be over 100W) I would say that for the gearteeth, a simple EP2 grease should do it.
I am however in doubt whether that grease will keep the pins and plain bearings in the epicyclic gears lubricated.
Right now, I am leaning towards a heavy duty gear oil like Epona 150 or maybe 220, hoping that the agitation will make it reach those pins
The gearbox, as received, appears to have been supplied a marginal amount of grease of questionable origins and quality. I have no idea how well that would hold up in use, and I tend to not really wanting to find out.
As for the type of shields, I have always operated under the assumption that metal shields were cheaper than plastic or rubber ones...
I am pretty eager to find out whether or how much improvement this will give as well, but I am fairly sure it will.
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Got home from work today around noon, meaning I have 2,5 days to get that gearbox installed before the weekend, when there is some RC boating to do.
The gearbox came with a very marginal filling of grease of which I had zero faith that it would ever migrate through the box to lubricate the spinny bits. Especially the bearings of the epicyclic wheels worry me a bit.
Better greases are availlable, but the downside of grease is that in order to replace it, the gearbox needs dismantling and solvent-cleaning.
So I decided to "waterproof" it, and use an oil filling. If I would drill a drainport, I can replace the oil without dismantling.
There is not much volume availlable, and since I simply LIKE doing stuff differently, I did the following:
I drilled a tiny hole all the way through into the bottom of the outer gear ring, and fitted a bent tube into that hole. This hole is located in the path of the epicyclic gear wheels, and I expect each passing of a gear, to push a tiny bit of oil into that hole, creating kind of a pumping action.
A 2nd hole is drilled 90 degrees offset to the first one, but also offset to exit in the plane of the rotating gear carrier.. With a bit of luck, this creates a circulation, where the epicyclic wheels push with each passing a tiny bit of oil in an external line directing oil towards the gear carrier.
(https://www.modelbouwforum.nl/attachments/20250702_191202-1-jpg.622631/)
The pic unfortunately is rotated clockwise 90 deg, the left side of the pic in reality is "bottom"
EDIT: and dang.... Not only did I manage to seal up that gearbox, the oil circulation actually works... A lot slower than I hoped, but never mind that... it circulates, and that's what's important!
I have Epona Z, a heavy duty gear oil, in three viscosity classes, 100, 150 and 220. If 220 turns out running hot, I guess I'll try the lower viscosities.
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EDIT: and dang.... Not only did I manage to seal up that gearbox, the oil circulation actually works... A lot slower than I hoped, but never mind that... it circulates, and that's what's important!
I have Epona Z, a heavy duty gear oil, in three viscosity classes, 100, 150 and 220. If 220 turns out running hot, I guess I'll try the lower viscosities.
To be honest, it is not even THAT slow... I hooked up the gearbox to a cordless drill to spin it with some velocity, and it turns out, there is some frothing of the oil, making the flow pretty good visible, and If I have to estimate (based on tube ID and flow velocity) about 1 ml/min, which sounds like "not a lot", but it means a circulation time of appr 2 minutes, because there's only 2 ml of oil in the gearbox. And at least, circulation means the oil REALLY gets everywhere.
As a nice side effect, since there is no way of looking INSIDE the gearbox, the transparent piece of tubing allows for at least a visual indication (colour) of the oil quality.
Next step: Hauling the engine out.
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Engine is out, and this situation:
(https://www.modelbouwforum.nl/attachments/img-20250703-wa0004-1-jpeg.622674/)
has to somehow change into something like this:
(https://www.modelbouwforum.nl/attachments/img-20250703-wa0002-1-jpeg.622675/)
I did some off the cuff calculations, which suggest that in the direct drive situation, the prop demanded about 1 Nm of torque to maintain 1500 RPM, at the pitch setting the engine would still pull at that RPM. Just as an indication: that is about the torque a 10 kg servo pulls.
Although intuitively one might think, that a reduction gear increases torque, this is not the case, it is the load that DETERMINES torque. The prop now spinning 3,7 times slower, means that the prop demands a lot less torque.
Meanwhile, firing up the trusty old Electric Jigsaw, because I have some carpentry to do, in order to install that gearbox.
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The rusty old electric jigsaw still functions well, so about 1,5 hrs (most of it "curing time") later, I basically ended up with this:
(https://www.modelbouwforum.nl/attachments/20250703_143724-1-jpg.622717/)
(https://www.modelbouwforum.nl/attachments/20250703_143731-1-jpg.622718/)
(https://www.modelbouwforum.nl/attachments/20250703_143741-1-jpg.622719/)
To my eye (I have a very vivid imagination, did I allready tell you guys?) it starts to look more and more like a true marine Diesel...
The boltholes are slotted to allow for alignment, and the bracket is built to be plane-parallel with the flywheel. That should make it possible to align the gearbox parallel and concentric with the crankshaft. to within a sufficient small margin.
One or two hours more to allow the aliphatic to thoroughly cure, I will slap on two coats of pore filler, and then two more coats of polyurethane parquet lacquer for oil and waterproofing.
The blocked portside cooling tube turned out to get unblocked very easily so now that we have ample cooling capacity, it also is time to install a controlled cooling bypass, which can be done in the meantime the coating of the gearbox-bracket is curing.
The way this is going, I expect to be able to do a bathtub-testrun tomorrow evening, which opens up tyhe possibility to take part in a Demo on Saturday.
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I know this pic is a near duplicate of one posted earlier, but it really is not.
(https://www.modelbouwforum.nl/attachments/20250703_194745-1-jpg.622763/)
The gearbox in its final installation.
The construction is strong enough to turn over the engine acting on the gearbox output shaft (against a 3,7:1 increasing gear ratio, takes considerable force) so I am more than positive that this will hold, and alignment seems to be quite OK.
Also did a quick 'n dirty bypass control valve for temperature regulation, no pics yet, will be posted later.
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https://www.youtube.com/watch?v=eZqfwz1ecFU
Not the prettiest video I've ever made, but I'm absolutely very satisfied...
Unfortunately I can't measure any bollard pull in the bathtub, but the first impression suggests that I've made considerable concessions in that area, but judging by the propwash the speed is still OK.
The engine runs a bit rougher and more irregular due to the lower torque load and especially the reduced inertia in the driveline, but this could also be a carburetion issue, because the engine is now running in a completely different load range.
I was a bit afraid of a lot of gear whine, but that's not too bad.
But then the advantages: WOW! I have "pitch control" like I've never experienced before with this boat. Stop is stop, and everything reacts immediately to small changes, whether forward, backward, or "a little more or less".
I've set everything up so that in forward position at 65% stick, the pitch is at full tilt. From 50% onwards, throttle is added as well.
The first part of the stick deflection is therefore purely pitch at more or less constant speed, the second part is mainly "speed controlled".
Where previously with the propeller in neutral position there was a lot of turbulence in the water, this has now almost disappeared. I think the "prop walk" has now also almost disappeared (previously Woutertje was turning on the spot at a fairly fast pace when stopped).
The temperature control also works brilliantly, responds well to the settings, only those settings are a bit "coarse".
In the bathtub test I saw the temperature go up and down by 2 degrees at most, where it was striking to see that when I gave full throttle, due to the higher speed (and therefore higher pump speed) the temperature first dropped by 1 degree.
When adjusting the control point, a reaction was visible within a few seconds, but the smallest step is soon 4 or 5 degrees.
I now have a temperature of between 74 and 76 degrees, one step higher and we soon see 80 degrees, one step lower and the whole thing goes to 70 degrees plus minus.
I have been running without a superstructure for a while, I see no strange vibrations or oscillations in the driveline, I think this is going well.
What I unfortunately did NOT see was oil circulation in the gearbox, but it could be that there was a bit too little oil in it.
I am happy, and this afternoon I will go to the club pond to test on open water, and then we will also do a bollard pull test.
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Really good work there, I don't know if you use Facebook or not. If you are on Facebook there is a group Model Engines - Old and New whose members would be really interested in seeing your work. It is a private group so you need to join it before seeing anything. Engines include I.C and steam.
Jim
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Really good work there, I don't know if you use Facebook or not. If you are on Facebook there is a group Model Engines - Old and New whose members would be really interested in seeing your work. It is a private group so you need to join it before seeing anything. Engines include I.C and steam.
Jim
Hi Jim,
I have too many groups and pages to attend to as it is allready, but you have my full permission to link to this thread, as well as the "gasoline Alexandra" thread in the sports&pleasureboats section, or the "Pimped Microcosm" in the steam section, in that facebook group.
Bert
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Well...
For a very first time sailing, not bad at all... Not perfect, I noticed that the completely different load and torque range in which the engine is now running has quite an effect on the carburetor settings. And since the fuel consumption has also visibly decreased (I think I have now sailed for a good hour with 150 ml, that was around 200 ml before) things are now EVEN more critical than they already were...
The engine stalled quite often on the water this session, and that is not nice of course, but that on-board starter is fantastic. I guess, with some finetuning, that will slowly get better.
What I expected turned out to be true: I have lost a lot of pulling power, but I do not know exactly how much yet, because my unster jumps on hold after a few seconds, and I spend too much time letting the boat rest fall into the wire. I really need some help with that. But from what I could see, it dropped from 1,9 kilo in the direct drive version, to about 1, maybe 1,1 kilo in this set-up.
I made a "towing resistance", just an almost filled (so still just floating) jerrycan.
That actually went quite well... Towing and filming at the same time is quite difficult, so just a short vid:
https://www.youtube.com/watch?v=KO_pu-FzcXs
Of course, the improved functioning of the propeller pitch control was also filmed, and this is also a cinematographic disaster of a film, but anyway:
https://www.youtube.com/watch?v=n34LlAlYJj0
The swift and unambiguous response of the boat is a HUGE improvement, propwalk indeed is virtually completely gone when the boat is stopped in the water, and this makes handling the boat when there is a towing line out behind it, a LOT easier and safer.
At the end of the ride, the drive belt of the water pump snapped (lucky, because I can see THAT on the telemetry, I still have to figure something out for the lub oil pump), so to be on the safe side, I replaced both.
This set has been on, if I remember correctly, since just before the engine was tinkered with in Woutertje, the hour counter is now at 6 hours, so I think I'll replace them every 2 hours to be on the safe side. Then I still have stock for at least 70 hours of operation.
I think the gearbox reaches about 60 degrees, about "hot to the fingertips, but no pull-back reflex".
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So I fired up the trusty old Ferm piece of crap masquerading as a lathe
{-)
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Not sure if you've already posted Brutus... how is the exhaust routed?
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Not sure if you've already posted Brutus... how is the exhaust routed?
I think I posted that, but can't remember for sure.
In any case, I routed the exhaust through the actual funnel. For that, I took off the funnel from the accomodation, worked out the innards so I could fit an aluminium tube all the way up.
At the engine manifold, I hooked up an old expansion muffler from a .12 class IC RC car model, which "more or less" fitted relatively conveniently.
(https://www.modelbouwforum.nl/attachments/20250220_145152-jpg.610515/)
The muffler is connected to the funnel-tube by about 20 cm (8") thin walled very flexible Silicone tubing.
(https://www.modelbouwforum.nl/attachments/20250421_113114-1-jpg.615850/)
It is a bit of a fuss to pop that tubing on the muffler, but once done, it usually does not have to come off again for a while.
So when the boat is sailing, it emits a nice blue plume of exhaust gas from the authentic place.
https://www.youtube.com/watch?v=_6-f_VWYC54
It is remarkable how positive people respond to that: "Oh, look, it even has smoke coming out"... Most people do not realize that that is not just smoke but actual exhaust gas from an actual engine... Funny, that...
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Me and my smug self...
Tested the boat yesterday because of a meeting today.
No problems yesterday, but today went through 6 or 7 water pump drive belts, none lasted longer than 2 or 3 minutes, but no apparent reason for the faillure.
Finally the last run, the pump turned out to be stuck, so I was of course pretty "xxxxx".
Initially feared pump bearings were shot, but it turned out I obviously failed to clean out all the metal debris from modifying the cooling system.
Had to open the pump to remove a few splinters, and flush out the entire system.
Tested the boat in the bathtub for 15 minutes, seems OK.
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Finally the last run, the pump turned out to be stuck, so I was of course pretty "xxxxx".
Oops... Apparently I used language that was off limits.
My sincere apologies to the users and mods, I really was not out to offend anyone.
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Since I hurt my back yesterday putting the boat in the water, I did not feel going back to the RC meeting today.
So I did a little maintenance (refreshed oil, regreased prop, adjusted valve clearances, nothing too fancy) and cleaned the "engine room" a bit.
Sump oil probably has been in the engine for about 5 runhours, and was black, but did not look "dirty" if you get what I mean. Pretty sure, the new charge can hold maybe 10 hours.
Put the boat through its paces one more time, for 30 minutes, most of it at full power, with occasional manouvering, mainly to fine tune the temperature control.
Since I now have variable RPM (and thus coolant flowrate rising and falling with RPM) this "following flowrate" apparently greatly assists in keeping water temperature constant. I draw that conclusion because I most definitely see controlling action of the bypass valve, and the temperature very positively follows the setpoint if I change that in the TX programming, but there is very little action based on "load": If the RPM goes up, the controlvalve more or less remains in the same position, and the temperature by and large remains constant. Which makes sense, I guess, since a higher flowrate at the same temperature also results in a greater heat transfer, apparently keeping pace with the also increased heat production.
The funny thing is: if the engine has stabilized at idle/prop neutral, and then full ahead is ordered, due to the immediate rise in flowrate, while the engine block is not yet "heat saturated", the temperature initially DROPS a bit, and vice versa, when the engine has stabilized at full ahead, and neutral is ordered, the heat-saturated block and now reduced flow cause the temperature to rise, ever so slightly.
I got that on (rather boring) video.
https://www.youtube.com/watch?v=HkTEqgTl8Bk
Also, due to the control system, the engine heats up much quicker, previously it took about 4~5 minutes for the temperature to stabilize (not very stable, I usually saw about 5~10 degrees C variation, depending on load and speed through water), but now it stabilizes in about 1~1,5 minute, and variation is 1, maybe 2 degrees.
I still want to try and install an oil temperature sensor, because of how I connected the coolant-bypass to end between oil cooler and liner-cooling.
After the moral dip of yesterday, now pretty happy about how the installation is functioning.
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Where last weekend (Saturday) was a total off day, today was the local club-evening, and Woutertje functioned flawless, for a full two runs of each approx 50 minutes, with a bunkerstop inbetween. The fuel tank was nowhere near empty at the first stop, but better safe than sorry. I think the tank allows about 90 minutes of runtime.
EDIT: Checking the "bunkerstation" it turns out I went through approx 250 ml of "bunkers"...
Bought myself a cheap inflatable dhingy, and duh, what do you think....
https://www.youtube.com/watch?v=VW7p_9WWX_8
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And a next step has been made:
A long time ago I made a "kinda-sorta" oil cooler for the Cison, basically the reasoning was "if it helps none, it also won't hurt none".
I still had a free temperature telemetry port, so a few minutes fidgetting with the sensor, a piece of brass tubing and opening the oil line after the pump, and presto, an oil temperature measurement.
Of course, this needed to be tested, because I wanted to know what kind of oil temperature we are running, and of course I also wanted to know if this oil cooler thingy actually does anything... (yup, ANY excuse to play in the bathtub... :p).
Tested for little bit over 15 minutes. Water temperature rose pretty quickly, in about 2 minutes that was above 70 deg C and stabilizing.
Oil temperature came up a LOT slower, took about 10 minutes to stabilize, and it ended around 56~57 deg C.
Now the interesting thing was that oil temperature followed load, but SLOWLY... At full ahead it crept to 57, at zero pitch, it VERY slowly dropped to 56. I repeated this 2 or 3 times to make sure, and it was repeatable.
The latter means that the oil cooler is ACTUALLY functioning, because the topside of the engine never dropped below 75 degrees, and that drop in temperature needs to come from somewhere.
55~60 degrees is a mighty fine temperature, loads of headroom, the oils I am using can easily handle 100 deg C or higher, but below 60 is very nice.
Only thing is, it is not hot enough for the oil to evaporate water or fuel, so it means regular oil changes to get rid of accumulated pollutants. But that is no biggie, it's only 25 ml per charge.
I'm a happy chappy again...