The Shipyard ( Dry Dock ): Builds & Questions > Steam

Reversing Mechanism

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Ken S.:
Hello Group:


I just picked up a Stuart Sirius steam engine and was wondering about my options to install a reversing mechanism.  I'm trying to get a layout set up.


Thanks for the thoughts.


Ken S.

derekwarner:
Welcome Ken...it will certainly be of benefit to read as much about the Stuart Sirius engines  :o prior to any further work

Following is a somewhat lengthy paragraph from the Stuart home page....

"The Stuart Sirius was originally designed for racing steam hydroplanes. Particular attention was given to the valve gear and steam passage design with the result that the engine produces great power using a surprisingly low volume of steam. Our tests have shown that running at 2800 rpm the engine produces 1/3 bhp. at 80 psi"

https://www.stuartmodels.com/item/59/stuart-sirius-unmachined

The last sentence in the 2nd paragraph has me a little perplexed  O0

Derek

pendlesteam:
As far as I know it cant be fitted with reverse. To reverse it would require a change in valve timing and there is no way to do this without making it a permanent change. Ive worked on a few of these and timing is critical.

malcolmbeak:
     That’s quite right, the Sirius engine can’t be reversed. Some piston valve engines can be reversed by swapping the intake and exhaust, but the engine doesn’t run nearly as well. I have an old Stuart MTB1 which has the same basic configuration as the Sirius (twin cylinder single acting with a piston valve) and I’ve just tried swapping the intake and exhaust and it doesn’t work.
In any case the Sirius will not always self start as there are only two power strokes per revolution, and even if it could be made to reverse, in a radio controlled boat, you could be left with a model out of reach and no power.
Derek, I think the 2nd para. means only castings and gears are included unlike most of the other Stuart kits that include other materials, nuts , bolts etc.
     
Malcolm
 

TheLongBuild:
I think My Modean engine goes faster in reverse,   %%   As can be seen going forward in this Months Model Boats Mag   :}

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