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[Martin (Admin)]

Can't wait to see this project on the water,

   ... got my wetsuit and Skis ready to go !   

[1967Brutus]

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.

[1967Brutus]

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... :(

[1967Brutus]

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...

[SteamboatPhil]

Your tenacity its an example to us all


Bon Courage 

[1967Brutus]

I am still convinced, this contraption somehow, someway, WILL be operational.

[1967Brutus]

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: The servo is in line with the linear movement of the throttle valve, and The controlrod will clear flywheel, driveline and exhaust system. Next step: RPM detection...

[1967Brutus]

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

[KNO3]

Great to see it running!

[1967Brutus]

State of affairs:




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...

[1967Brutus]

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...

[1967Brutus]

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.


Pitch servo has been installed. The servo mount has to be sturdy, since the required actuating force is pretty high.



The engine is in place, and bolted down this time... I expect it to stay there for a while...


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.



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.

[1967Brutus]

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...

[1967Brutus]

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...

 

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.

[1967Brutus]

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:




Bolts removed, due to the bottom stud being very short, the rudder can easily be tilted out




and the rudder lifted out





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.

[1967Brutus]

Every day a bit more progress... Things start to function... a bit better than the day before


https://www.youtube.com/watch?v=kiRjcK16TYI

[Colin Bishop]

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

[1967Brutus]

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.





Hope to also fit the starting electrics.
Still plenty to do...

[1967Brutus]

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.



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.

[1967Brutus]

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.

[1967Brutus]

https://www.youtube.com/shorts/B-1DDHUXVjs

[1967Brutus]

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

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...

[1967Brutus]

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:



the shaft end, that is in the pitch yoke, the sheared locking pin visible:



The flange at the end of the tunnel:




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...

[JimG]

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

[1967Brutus]

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.