Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Steam => Topic started by: captain_reg on August 01, 2023, 07:20:22 pm
-
I'm currently restoring a Graupner Glasgow with a Cheddar Models steam plant. I've read a lot about the various different sensors for monitoring the boiler water level but there is just something about them that doesn't take my fancy. Can't quite put my finger on why but it has got me thinking, has anyone ever tried to use a live video feed to a shore based monitor and just visually keeping and eye on the water level and pressure. I'm thinking a drone style FPV setup linked to a 3.5inch monitor mounted onto the transmitter. Spare channels on the transmitter would be used to control the gas valve & water pump. I've not got any of the equipment either way so cost I estimate would be about the same either way.
Anyone tried anything similar? Can anyone think of any problems that I'm missing?
-
Bonjour,
My friend Eric has tested a FPV system on his boat : https://youtu.be/yttHfVIZ1XQ (https://youtu.be/yttHfVIZ1XQ)
Personnally, see my own topic in the same thread, I have had the opportunity to ask my friend Jean-Marc a simple sensor which lights on a LED or a relay when the boiler water level is empty.
This means that some water remains in the boiler, quite enough to bring the boat back. For example, my 100 x 160 mm horizontal boilers contain 900 ml of water in total and only 600 useful visible in the water level
Very simple (important), cheap (also important), I will install my first one in a boat which has an electric pump that I will manually manage to avoid all possible electronic issue.
I wouldn't install any sensor on my boats equipped with couples pumps as I have tested them, measured theur autonomy, know how to manage the bypass valve and trust them, example : https://youtu.be/QqgnnKakl_o (https://youtu.be/QqgnnKakl_o)
-
It’s great to hear that you are experimenting with these ideas. I have installed several systems, and all work, the choice usually dictated by space,weight and budget. There are very good systems available for controlling the , gas, the water level or both. Here is an example from Dènes of a great water level controller. https://youtu.be/Pf-3yVGfrVg (https://youtu.be/Pf-3yVGfrVg)
-
Here is a link to a video of a camera set up as an experiment on the boat to monitor the boiler pressure, the camera is small but the transmitter board and 12v battery all took up space. Care also needed since the camera gets hot
https://youtu.be/A0W8UeumhRs (https://youtu.be/A0W8UeumhRs)
-
Here is a link to a video of me setting up the pilot light setting on an automatic gas control unit made by Dènes, it’s very effective and it’s better than the Stuart/Cheddar version because it’s not just full on or pilot, the Dènes version gradually increases and decrease the gas to ensure the boiler pressure remains constant. It’s easy to install and setup, it works really well
https://youtu.be/ACWF3svmx_8 (https://youtu.be/ACWF3svmx_8)
-
Thanks all, seems like the idea has promise. I'll give it a go and see where I get to.
RegardsRichard
-
Bonjour Richard,
As you may notice it, we have different solutions which correspond to different purposes.
Take your time to define your need/want because it has a possible important financial differential.
The more complex is the facility, the harder it becomes to find a solution to an issue if it occurs.
And the room/energy... needed are also parameters to be taken in account.
As steam passionate, one of my future goal is to install a steam pump like this example https://youtu.be/hSwG2p45iGY (quite smaller than the Stuart one) on one of my steam plants.
Even if I have a large fleet, not obvious to find the appropriate boat :}2
-
This is how I solved it: Assuming a burner control of some sort is used, so boiler pressure can be considered "constant" (it does not really matter HOW constant, because any variations in that pressure also are determined by the position of the steam control valve, therefore repeatable), the steam consumption is determined by the steam control valve. Which means, water supply should follow the position of that steam valve.
I have a transmitter with decent programming possibilities WRT slaved channels and curves.
I installed a feedpump with speed control (in my case the "electronic" version of the Regner feedpump), and slaved that channel to the throttle.
Then I did four runs, each run at one constant speed, and of course each run at a different speed (test basin recommended for close observation of the boiler level), and adjusted the pump speed curve for each of those power settings.
It keeps my boiler level absolutely stable for the duration of a full feedwater tank, without ANY form of control, or additional subsystems.
One of the reasons why I prefer simplicity over "control systems" is that the waterlevel in the boiler is affected by load changes, and a feedwater control cannot do anything but respond to those immediate and sudden level changes, while in reality it should NOT: it should only respond to trends in the water level.
For example: if after a period of low speed steaming the steam control is suddenly opened, the water level will show a quick increase due to the intensifying of the boiling process caused by the pressure drop. The pressure drop will cause the burner control to open fuel supply, boiling intensifies even more. At that point in time an active feedwater control will reduce or even stop the feedpump temporary because it sees a high water level, while in reality the boiler still contains the same amount of water, but needs MORE water, not less, because it is delivering steam at a higher rate.
Opposite is also true: Coming from a period of full speed steaming and the throttle valve is closed, the boiler level will initially drop, leading to increased activity of the feedpump.
Like in all controlled systems, time is a factor here, and depending on how often the throttle valve setting is changed, this can lead to "oscillation" of the waterlevel.
In itself, this will usually NOT lead to any problems with the boiler itself, usually the water level margins will be wide enough. But it will affect the "quality" of the steam the engine receives (wetter or drier), which can cause issues with irregular lubrication in case of a displacement lubricator, and also the oil separator (assuming one is fitted) might fill up quicker than necessary.
The latter especially became an issue for me when the operating time of the system as a whole started to exceed the safe operating time of the oil separator: I had to come in for "slops disposal" halfway, which was annoying.
Based in real life engineering experience, I am a strong believer in striving for an as stable operation as possible. Each factor in and of itself has not that much effect, but all factors combined can result in very significant improvements, even in small scale installations.
And isn't "optimizing" an important part of the fun we have?
-
Well done for this new approach and thankyou for taking the time to update us with the results. Every day is a School day with steam and I have enjoyed learning more from your experience.
-
This is most certainly not a new approach this is going back to the philosophies that were used to control levels before we ever saw the first Cheddar electronic ABC unit.
Most systems then used an engine pump, driven from an eccentric on the crankshaft, which went through a two port valve to either feed the boiler or return to the feed tank. The valve position and hence the direction of the output being adjustable. Engine revs was a reasonable approximation to water consumption, certainly for the length of time a model was expected to be on the water. By a coincidence I have only in the last few days been explaining to a chap that a more modern parallel to this system can be to use an electrically driven pump, through a speed controller, which takes it's signal from a 'Y' lead on the throttle channel. It's exactly the same set up using engine speed to control the water fed into the boiler. Using a two port valve allows adjustment for varying conditions but, as 1967Brutus has indicated, once you have the valve position set by a few trial runs it is surprising how stable the water level can be.
There is actually a model boat in our club that uses an electric motor driven feed pump, through a speed controller, which gets its signal from the throttle channel, that I have been annually testing for a number of years. It works perfectly.
Another option to consider is controlling a servo via the throttle channel, which operates the two port valve such that an increase in throttle pushes the valve lever further to the feed position. I'm with 1967Brutus though, probably because we are both marine engineers, as regards the philosophy of keeping things simple.
-
This is most certainly not a new approach this is going back to the philosophies that were used to control levels before we ever saw the first Cheddar electronic ABC unit.
:D don't get me wrong, not pretending I invented something new here... But with the nowadays availlable transmitters (I use a Taranis) it can be perfected to better than 1 mm of waterlevel per 10 min... and for operating periods of close to an hour regardless of throttle regime And THAT is "new"... :D :D :D
And apart from being simple and reliable, above all it is something that is incorporated into a lot of transmitters nowadays without people knowing about it. Both my automated burner control and this feedwater thing were within the programming capabilities of the Taranis, and did not cost me any money...
Marine engineers like "cheap" too :D :D :D
-
It would be interesting to see a comparison between using using the pump speed controller as a slave channel to the throttle then incorporating a curved relationship in the transmitter with simply using a 'Y' connector in the model from the throttle channel to feed both the throttle servo and the pump speed controller. Obviously then you have the less accurate proportional relationship balanced against the significantly simpler physical set up. Not everyone has a radio with such capabilities and, of those that do, not all of them want to get involved with such procedures.
For a typical period of time on the water would the less accurate relationship justify the more complex set up of the transmitter?
-
It would be interesting to see a comparison between using using the pump speed controller as a slave channel to the throttle then incorporating a curved relationship in the transmitter with simply using a 'Y' connector in the model from the throttle channel to feed both the throttle servo and the pump speed controller. Obviously then you have the less accurate proportional relationship balanced against the significantly simpler physical set up. Not everyone has a radio with such capabilities and, of those that do, not all of them want to get involved with such procedures.
That is a bit tricky, because at least the Regner pump such as I use, only utilizes one side of the servo signal and then only half the range. Meaning it starts running from "midstick" and allready runs full speed halfway the stick travel. Suitable for a steam valve/reversing function that is closed at midstick and goes in either direction off-midstick, but I have a separate controlled steam valve and a separate reversing function.
I allready had the Taranis for several years and absolutely LOVE the virtually unlimited possibilities it offers, so for me a no-brainer, but I can see your point of not everybody having such a set-up.
For a typical period of time on the water would the less accurate relationship justify the more complex set up of the transmitter?
Hard to say: for a 10 minute operating range, I do not need a feedpump at all, for a 20~25 minute operating range, a single speed pump would most likely suffice as well. Anyone happy with that kind of endurance, I would strongly suggest to indeed not even bother.
A bit of a revelation about myself: my YT handle is not for nothing "rigididiot", I am amongst other things, like being a marine engineer, also slightly autistic (which might be related to my choice of profession, I never figured that one out really :D) and I just wanted to see how far I could stretch that endurance without resorting to exotic materials and equipment. But THAT is the topic of my thread about pimping the Microcosm... ;)
So please keep in mind, NOTHING of what I post is a "reccomendation on how people should do things", at the very best is is a series of alternatives to common used set-ups intended to provide inspiration, or to jog peoples minds, and I always try to keep at least materials and such as low tech/cheap as possible.
-
There is a lot to be said for the simplicity of an engine driven pump. If it has been designed properly by the manufacturer it should be a fairly close match to the demand of the engine.
-
There is a lot to be said for the simplicity of an engine driven pump. If it has been designed properly by the manufacturer it should be a fairly close match to the demand of the engine.
True... There is a lot to be said for simplicity...
But it also robs a LOT of power, relatively. With an eccentric driven plunger type pump, power consumption of a feedpump rated to match the consumption of the engine, is close to 10% of indicated engine power...
For a pump rated for overcapacity, capacity control via throttled bypass, that power consumption rises proportional with pump capacity.
If alternative the pump has overcapacity and boiler level is controlled by means of full open or full closed bypass (on/off control) the pump loss becomes very noticable in the drop or rise of engine RPM every time the valve is switched.
There are downsides with every system: an electric pump robs that same amount of power from the RX battery, and that is a significant load: in my boat the pump consumes 80~90% of the total electric consumption), so there is a significant reduction in operating time of the RX.
We all have to pick our poison then drink it, I guess. All we can do is share the info and each decide for ourselves.
I have stumbled too often over "it should be..." when in hindsight it wasn't... Me opting for the cheapest options of course could play a role in that :D :D :D
That is one beautiful engine, by the way!
-
Bonjour,
The possible lack of power is not an issue as soon as you add the pump to a powerful machine, I personnaly go :
- from 8 cm3 https://youtu.be/TnNkqDPZnWw in my tug Abeille 13 https://youtu.be/f3AbEtBcb4I
- To 20 cm3 https://youtu.be/hHnH30v66xA in my launch Moune https://youtu.be/QqgnnKakl_o
I prefer simplicity to complex electronic devices :-))
-
Bonjour,
The possible lack of power is not an issue as soon as you add the pump to a powerful machine, I personnaly go :
- from 8 cm3 https://youtu.be/TnNkqDPZnWw (https://youtu.be/TnNkqDPZnWw) in my tug Abeille 13 https://youtu.be/f3AbEtBcb4I (https://youtu.be/f3AbEtBcb4I)
- To 20 cm3 https://youtu.be/hHnH30v66xA (https://youtu.be/hHnH30v66xA) in my launch Moune https://youtu.be/QqgnnKakl_o (https://youtu.be/QqgnnKakl_o)
I prefer simplicity to complex electronic devices :-))
:D :D :D I have only one engine to choose from :D :D :D
-
True... There is a lot to be said for simplicity...
But it also robs a LOT of power, relatively. With an eccentric driven plunger type pump, power consumption of a feedpump rated to match the consumption of the engine, is close to 10% of indicated engine power...
For a pump rated for overcapacity, capacity control via throttled bypass, that power consumption rises proportional with pump capacity.
If alternative the pump has overcapacity and boiler level is controlled by means of full open or full closed bypass (on/off control) the pump loss becomes very noticable in the drop or rise of engine RPM every time the valve is switched.
There are downsides with every system: an electric pump robs that same amount of power from the RX battery, and that is a significant load: in my boat the pump consumes 80~90% of the total electric consumption), so there is a significant reduction in operating time of the RX.
We all have to pick our poison then drink it, I guess. All we can do is share the info and each decide for ourselves.
I have stumbled too often over "it should be..." when in hindsight it wasn't... Me opting for the cheapest options of course could play a role in that :D :D :D
That is one beautiful engine, by the way!
I'd be interested to know how you arrived at the 10% figure but would question whether IP is as relevant as actual power for such a comparison? Surely the biggest factor in the amount of power required would be the WP of the boiler, as that is what the pump piston has to overcome? This is obviously accommodated by the fact that a small diameter pump piston is used and WP is frequently in the 3 bar range or less for most of our models.
I actually don't think 10% is too bad anyway, bearing in mind that most of us use a plant that has a significant amount of spare capacity in the first place. I think when you consider the weight of an engine driven pump against the option of an electrically driven pump as well there are a lot of aspects of the balance to consider. For the chap I mentioned above he already had 6v available from an existing power supply and he didn't have any room on the crankshaft for another eccentric so we decided to go electric but my first choice is always an engine driven pump if possible.
-
I'd be interested to know how you arrived at the 10% figure but would question whether IP is as relevant as actual power for such a comparison?
First the use of "IP"... for small steamplants like mine, there is not much to go on other than IP, and it follows (under the assumption of minimal pressure losses in the piping, throttle, slidevalves etc etc) simply from boiler pressure times displacement times RPM.
I haven't taken the trouble to ACTUALLY measure shaft output (I have done that in the past for other projects and when I set my mind to it, I can fairly accurately physically measure shaft outputs in the 5 to 50 W range). It is only relevant in that the theoretical max output of for example my Microcosm is give or take 30W @ 1000 RPM. Reality is a LOT lower. Let's optimistically say it's 20W on the shaft, give or take.
Pump power is fairly easy: Total efficiency of small plungerpumps or gearpumps (positive displacement pumps) by experience is in the order of magnitude of 5%, which is a general rule of thumb by personal experience, also valid for window wiper pumps and the likes. Aquarium or pond pumps do not do much better by the way.
One can easily calculate the output power, volume flow times pressure directly calculates a power. 1,5 bar (0,15 MPa) times 0,6 ml/sec is 0,09W. Multiply that by 20 and you've got the total power consumption, give or take.
Meaning the absorbed power of the pump is 20 times that, or order of magnitude of 2W. (and current draw of the Regner pump more or less confirms that at a measured 300~400 mA @5V).
That is for my installation, and it stands to reason that an engine of 10 cc displacement, or 15 cc, will develop proportionally more power but also reqire proportionally more feedwater, which will increase the power consumption of the pump proportionally.
I actually don't think 10% is too bad anyway, bearing in mind that most of us use a plant that has a significant amount of spare capacity in the first place.
It is not a big deal, it just is something to consider, because whichever way you turn it, steam is not the most powerful boat propulsion out there, and VERY voluminous for very little power. So "spare capacity" only happens when a large installation is used, and that contradicts "availlable room".
I visit a fair amount of shows, and most steam powered boats I see are not all that impressive WRT performance.
Mine isn't a raceboat either, but I know it can hold its own among other steam powered boats.
[/size]I think when you consider the weight of an engine driven pump against the option of an electrically driven pump as well there are a lot of aspects of the balance to consider.
That I can't confirm. True, a mechanically driven pump alone is lighter than an electrical pump, but not when all gears, mounting brackets and the additional piping (electrical pumps can be placed in the most convenient place, engine driven pumps have to be located on the engine and often require more tubing, a possible bypass valve and a servo to operate that valve) are taken into account, then you end up fairly equal in both weight and complexity.
For the chap I mentioned above he already had 6v available from an existing power supply and he didn't have any room on the crankshaft for another eccentric so we decided to go electric but my first choice is always an engine driven pump if possible.
What can I say? So was mine... When I ran my installation for the first time and it became clear that I was going to need a boiler feed, I did not think but ordered a mechanical (engine driven) pump... Instant gut reaction.
Then I started thinking, and I concluded that while it is the "traditional" solution, it also is the inferior one for a wide array of reasons.
I absolutely can see the appeal of an engine driven pump (:D I'm an engineer, right?), but it is not the logical one from a tech POV.
But the power supply is a non-issue: We ALL have 5 or 6V availlable if we're talking model boats. It's what we power the Receiver and servo's with.
My feedpump runs directly off the RX battery. A common 4 AA cell size receiver pack will power the entire set-up for about 4 hours including non-stop pumping.
-
This is a very interesting thread. I like the idea of programming the r/c so it operates an electric pump in relation to the engine steam throttle valve. And since I have a Taranis radio I haven't used yet, it is a good thing to try to learn.
-
This is a very interesting thread. I like the idea of programming the r/c so it operates an electric pump in relation to the engine steam throttle valve. And since I have a Taranis radio I haven't used yet, it is a good thing to try to learn.
If you are interested, I can show you how it is done. And I have gone one step further: Taranis can do a proportional timer (a timer that runs quicker or slower proportional to for example throttle value) This timer is set to count down, and it counts slower if throttle is closed.
Since the pump is linked to the throttle, thus the remaining water in the feedwater tank is ALSO linked to the throttle, I now get a warning for low level without having a floatswitch or level measurement. Tested and working pretty good.
I have progged timer one as a runhour counter. It functions on a logical switch that returns "1" if two conditions are met:
Condition 1 is steam valve open (value for % of opening is the smallest where the engine will run)
Condition 2 is boiler pressure above 50% of set value.
This timer keeps track of the actual runtime of the engine, ignoring the time the system is idle or for example the boiler still busy raising steam.
Timer 2 is used as feed water level warning. The time set for this warning needs to be determined empirically, but I am using this now since about 7 or 8 runhours, and it has so far proven to be reliable. I can send the boat out to the pond, and be confident that by the time the warning comes, I have 15~20% water left.
But you definitely need a stabilized onboard voltage, in order to have an as consistent as possible pump speed, and you need to take your time determining the proper pump curve. It is absolutely NOT difficult, but it is pretty time consuming.
You also need a properly functioning pressure control (regardless of HOW that is done, what is important is that boiler pressure is consistent).
please, just to prevent confusion due to translation: "consistent" is not the same as "constant". Boiler pressure does not have to be absolutely constant, but it needs to be predictable, responding always the same to a certain situation.
If you need assistance in setting up the programming, just give me a shout.