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[kno3]

Hello!

I have what I believe to be a marine plant with a Cheddar boiler and a Stuart single cylinder oscillating engine ()I'd appreciate your opinions if I guessed the makers correctly) and I'm planning to build a boat for it.
To make sure the boat doesn't end up with a stalled engine out on the pond, I'd like to make a sort of electric starter. That way one could play with the throttle without problems.

So I was envisioning a small electric motor that has a wheel with a rubber gasket on it. This engine would be mounted on a hinge, so that when it gets the signal from the remote control the motor with rubber wheel can press on the steam engine's flywheel to turn it for starting. Upon releasing the command it would fall back and disengage the steam engine flywheel.

Before building I'd like to ask if you have tried to build a starter for a single cylinder steam engine before? What device did you use, perhaps there are others better than my idea?

[Bunkerbarge]

The type of device you are referring to tend to get complicated and therefore unreliable and hence detract from the simplicity of the plant.

My suggestion would be, as I intend doing sometime in the future with a similar arrangement, to use a controllable pitch propeller.  Simple to control and no additional clutter in the model.

I don't know if anyone makes them at the moment but keep an eye open for them on eBay or other second hand outlets.  You would even be better trying to make one than the unit you are referring to.

[HS93 (RIP)]

Yes it is cheddar its a Pipit. I have seen a simple hinge with a small 280 size motor fixed to it that is spring loaded to hold it away , to start a servo pushes the motor which also pushes a small micro switch that starts the motor so the motor is running before it hits the flywheel. a simple idea would be a kitchen rudder there was one in model boats by I think his name was Edward Komstat ? chap from the contanant who I think started or pushed the mini Vap series. this will also give you reverse and you can controle speed roughly without touching the steam valve. and would only rec 2 channels.

Hs93

[sheerline]

What about a small clutch arrangement such as that found on model nitro cars. Refit it with weak springs so it will pull in at the low rpm experienced with small steam plants and it will begin to bite as you slowly speed up the engine. It could be arranged so the engine slowly idles in the stopped position with no drag on the clutch....just a thought.
 
A constantly engaged small motor would be a feasable idea and would, if geared correctly with a pulley, impart only a small load on your engine . If configured this way you would only need one sevo operated switch to engage it and this could be arranged to work from your throttle servo so it came on just as you move the contol lever forward and go off just as the engine started to run at very slow idle.
 If constantly engaged with the engine, you could also use the motor to power your navigation lights as it would run as a generator but if you do this, it will load your engine to a degree as lights obviously require power.
 As Bunkebarge has pointed out however, it detracts from the purity of a steam plant and does add a complication to the sheer simplicity of your engine.
If you like tinkering, give it a try as it would be an interesting little excersise.

[bogstandard]

If you go down the page here a little bit,

http://www.modelboatmayhem.co.uk/forum/index.php?topic=6781.80

I did a rough sketch and explanation of how to do exactly what you are talking about. Using a few gears. It has the advantage that as the engine restarts, and the electric motor is turned off, the gear is thrown out of the way awaiting the next time. It can also be used for emergency rescue.

John

[kno3]

Thanks a lot for your answers! I have looked at your gears and it seems to be a pretty simple solution, so I'll give it a thought.
Let's see if i can find the necessary gears to build it.
Might also try my original idea with motor directly on the flywheel, via hinge.

Anyway, this will take some time, as I have to finish my current steamtug project first.

[Bee]

Find in an old clock or meccano  or make a toothed wheel just a little larger than the flywheel (for looks not operation) and attach to the flywheel. Arrange two little levers (pawls), one for each direction,  that can engage a tooth and push it forward one or two teeth with very little movement. When retracted the pawl should be held clear of the teeth by a banking pin. With ingenuity connect these pawls to engage using the over-run of your servo. You may have to waggle the control a few times to move enough teeth but perforce when it gets over dead center it will be at full throttle to get away cleanly. It is not complicated and made in brass will enhance the look of the engine.

[kiwimodeller]

Hi, this may be a bit late for you but over the weekend we were talking at the lake about the same subject and one of the members said he had seen a setup where the electric motor was permanently connected to the flywheel with a rubber O ring and geared down with only a small pulley on the electric motor. It was wired in such a way that when the steam plant was running the electric motor acted like a generator and ran a lightbulb on the cabin top. If the light was shining the motor was running! If the light went out the owner adjusted the trim on the throttle control to giive extra movement to the servo which then turned on a switch to feed battery power to the electric motor. This meant he could still get away with two channel radio. Apparently even if the steam engine did not start again the electric had enough power to get the boat slowly home. Sounded neat and I will put it on the list of things to try "one day". Most small electric motors spin fairly easily so I cannot see any disadvantage with it being permantly engaged to the plant. Hope this helps, Cheers.

[kno3]

Guys, thanks, this is very helpful. I have a few alternatives now to consider.

I am still busy with my other project (the steam tug) so any input is good, as I won't do anything with the single cylinder engine until I finish the other.

[Bunkerbarge]

Obviously lot of potential ideas but to me, being an engineer, you can't beat the simplest and technically efficient solution. 

All the motors, clutches, switches, gearboxes and linkages incorporate losses and potential unreliability and, at the end of the day, whilst looking impressive in a Heath Robinson type of manner, don't come anywhere near as elegant, simple and infinately more relaible than a controllable pitch propeller.

[kno3]

I'd love to have a propeller with reversible pitch, but couldn't find a metal one to buy anywhere. At the moment I don't have the tools necessary to make one myself.

And by the way, the controllable pitch propeller is not the perfect solution either, because I would still need a way to restart the single cylinder engine, should it stall.

[Bunkerbarge]

You adjust the throttle control to come down to a tickover at minimum setting so the engine never stops.

If you are unlucky enough to snag the propeller and that stops the engine then you are only faced with exactly the same situation if that happens with an electric driven model and you blow the fuse.

....and don't forget nothing of course is ever perfect anyway.