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[rfurzer]

I am working (slowly) on my steam tug for a stuart 10v - and plan to use a variable pitch prop- the best solution that I can see.

I am aware that a multi-cylinder engine with a 90deg crank will have no dead centres and will self start.

I have read somewhere amongst these pages about a "tumbler" design by Bogstandard being a possible solution, but can't find any details as to what that is and how it might work.

Furthermore, another (stupid?) idea of mine-  is there any reason why a compression spring could not be used in the cylinder head space - able to be fully compressed during a normal cycle but offering a reason to stop before D.C when the throttle is closed? I appreciate that it might be undesirable from an efficiency point of view. Closing the exhaust to stop the engine and then shutting off the steam might do the same thing??

[derekwarner]

Mr Furzer.....just as ball bearings are rated at a B10 [ten million cycles] ...... spring material is also similarly 'cycle' rated 

Anything built in to an engine that will self destruct would be of questionable advantage  ....... Derek
__________________________________________________________________________________
courtesy of GOOGLE..........
"Plastic deformation does play a role in high cycle fatigue; however, the plastic
deformation is very localized and not necessarily discernable by a macroscopic evaluation of the
component. In summary, while a valve spring designer may consider a failure at 10,000 cycles very short
life, the failure can still be the result of high-cycle fatigue because the material response at the
microstructural level is the same as in a 10,000,000-cycle failure under lower applied stresses"

[rfurzer]

Ok fair enough Mr Warner. 10 million cycles will be a fair bit for my little tug 'tho - 500 hours of happy boating. Hopefully my variable pitch prop will last as long (if and when etc). What is the TBO for a 10V in a model tug?

Your smiley seems jolly cross too!

Russ

[kiwimodeller]

Variable pitch props are great and I have never had the engine stop yet as the revs always rise when the prop is moved to the neutral position before it is put in reverse. If you are worried about the engine stopping then the best solution is a small electric motor operated by a switch or speed control and driving the steam engine by an O ring to the flywheel. Using this method the electric motor can restart the steam engine or if there is another problem (such as the burner going out) then by reducing the pitch of the prop the electric motor will have enough power to drive the boat back to the bank. It is another complication to fit the motor, battery and controller but it will give you the peace of mind of having another way to get the boat home. Cheers, Ian.

[rfurzer]

The electric motor idea seems sensible. Like driving through a snow bank on the starter!

Any idea what the "tumbler" might be?

[hammer]

 I saw somewhere on the net, a French single cylinder engine with a device which pushed the flywheel if it stopped at TDC. A servo with a rod would do the trick. Hammer

[ooyah/2]

I saw somewhere on the net, a French single cylinder engine with a device which pushed the flywheel if it stopped at TDC. A servo with a rod would do the trick. Hammer

Not a bad idea, but what if the engine stops at B.D.C.
I think that the French engine was a piston valve , not a slide valve like the 10V.

George.

[hammer]

Well George in that case I guess the engine will have to be double acting.

[frazer heslop]

If I didnt keep getting side tracked I should have built one by now for my next little boat build
http://api.viglink.com/api/click?format=go&key=190cd6dc27c66f8edf4cd0d943583f3b&loc=http%3A%2F%2Fmodelsteam.myfreeforum.org%2Fabout57177.html%26highlight%3D&v=1&libid=1355257107948&out=http%3A%2F%2Fwww.typhoon-motors.com%2F&ref=http%3A%2F%2Fmodelsteam.myfreeforum.org%2Fsearch.php%3Fsearch_id%3Dnewposts&title=The%20Unofficial%20Mamod%20and%20Other%20Steam%20Forum%20%3A%3A%20new%20model%20engine%20manufacturer%20-%20Typhoon&txt=http%3A%2F%2Fwww.typhoon-motors.com%2F&jsonp=vglnk_jsonp_13552571100902
Oh my thats a long link but should work

[ooyah/2]

Well George in that case I guess the engine will have to be double acting.

Hammer

I assumed that you knew that 10V's were double acting.

George.

[rfurzer]

I saw somewhere on the net, a French single cylinder engine with a device which pushed the flywheel if it stopped at TDC. A servo with a rod would do the trick. Hammer

What about a sliding bar with a short rack that can engage a pinion on the flywheel, turn it and then move clear (out of mesh) when activated by a servo. Some deliberate backlash might help its operation.

[ooyah/2]

What about a sliding bar with a short rack that can engage a pinion on the flywheel, turn it and then move clear (out of mesh) when activated by a servo. Some deliberate backlash might help its operation.

Russ ,
This idea has been used before, the movement of the rack kicks the engine over either T.D.C  or  B.D.C.

You could also consider fixing a gear pinion to the main shaft and turn it over with a larger sprocket and use slip eccentric method.
This would mean that you would have to turn the shaft over 120 deg either way.
A spur wheel on the 9/32 shaft would need to be about 20 T and have approx 5/1 ratio on the big sprocket which can have the sprocket teeth removed over the quadrant when the travel has been established, this leaves the rest of the sprocket wheel to make an arm for your servo.
By using slip eccentric you don't need the variable prop, I have successfully used this on a 10 V in a large tug untill I installed a D 10 with full reverse gear.
Unfortunately I can't post pics as my Mac doesn't have Windows but if you wish to P.M. me your mail address I can send you a sketch of the set up.

George.

[hammer]

Sorry George I know nothing about Stuart engines. Except they are on the large side. Just build my own designs.

[ooyah/2]

Martin has suggested that I try to post pics by his method, this was posted on Chit Chat so here is a try.

Russel.
Here is some pics using a small gear box to reverse and start the engine, if this is successful I will describe the G/Box in more detail.

George.

Sorry Russ,
Still no joy on posting pics, this is what comes up.

g:box with s:eccentric:1.
You cannot upload that type of file. The only allowed extensions are txt,doc,jpg,gif,pdf,PNG.

[rfurzer]

Thanks George
The pics you emailed me by PM are .jpg, so not sure why 'the computer says no'.
Russ

[KBIO]

Hello.
If I can give my opinion!
Having experienced those different methods of "reverse", I wish to share .
- The electric motor rubbing against the flywheel or other is not reliable (at least in my case). Always oily, or the engine is water locked or for some other reasons, it does not work when I need. But , I agree that you are probably more clever than i to make a proper installation.
- The variable pitch propeller is wonderfull , but cost concerned and generally fitted on good size engines & boats.
-The gear box is reliable and chip to install.
-The Typhoon single cylinder , double acting engine with the piston valves is easy to work out.
When the engine stops (mandatory) to the TDC or BDC, there is two pins on the flywheel that are excentred with a small angle.
(not aligned with the TDC/BTC.
The servo moves an arm wich pushes one of these pins, thus, displacing the piston a bit and allowing the steam to enter.
The engine runs in the direction that the arm has moved to.
99% reliable by experiment. Brilliant idea, cheap and easy for small engines. (or bigger, why not??).
-Using pignons to reverse the rotation, must be a bit tricky to work out. I do not have experienced  this one.

Hoping to have been a bit helpfull.
Regards.
KBIO
http://modelismenavalradioc.nouvellestar6.com/c9-modelisme-bateau-a-vapeur

[rfurzer]

Thanks KBIO.
I went to your link- sure wish my French was better- there was lots there that looked interesting

[derekwarner]

Mr furzer...........

All of the content of http://modelismenavalradioc.nouvellestar6.com/c9-modelisme-bateau-a-vapeur

.........is able to be translated to English ....either as a facility within the WEB site or within your PC operating system

& so........bonjour KBIO..maybe the birds have flown? .............Derek 

[rfurzer]

Ah- you again Mr Warner !

Regrettably, I find that the automatic translation is of doubtful intelligibility. I prefer to struggle through with my schoolboy French.

'Merci bercoup' for your advice 'tho

[ooyah/2]

What must be remembered here is that the original thread was for a 10V engine which is a slide valve and can't be operate as the French engine..

The French one is a piston valve engine and easy to convert as the engine only requires the exhaust to be transferred to the steam inlet and vice verse to rotate it the other way, along with a little kick to start it.

George.

[ooyah/2]

Here is another method of reversing and self starting a 10V slide valve engine using a reversable electrically operated G/Box and Slip Eccentric on the engine.
George.

[KBIO]

Hello!
Here is a video to help :http://youtu.be/LG8fiJMXzhg
I agree with Oyaah, a slide valve wouldn't work in this case, or would be really tricky to have it working.
Above all with the "lips" of the valves.
Regards.
  KBIO
http://modelismenavalradioc.nouvellestar6.com/c9-modelisme-bateau-a-vapeur

[ooyah/2]

Hello!
Here is a video to help :http://youtu.be/LG8fiJMXzhg
I agree with Oyaah, a slide valve wouldn't work in this case, or would be really tricky to have it working.
Above all with the "lips" of the valves.
Regards.
  KBIO
http://modelismenavalradioc.nouvellestar6.com/c9-modelisme-bateau-a-vapeur

Yves,
It's impossible to reverse and self start a single cylinder slide valve engine  without slip eccentric and some thing to turn the engine over from T.D.C  or  B.D.C.

GEORGE.

[KBIO]

  Yes George.
Ad I said , I do not see how to reverse this type of engine.
Cheers.

[hammer]

The original post did not mention reversing, only stalling on TDC.