First Stirling Motor

[hermanpwillis]

Hi, I'm new here and interested in building my first Stirling Motor....hopefully this year. My reason for wanting to do this is to power a small boat. I would like to build a PD Racer and put a Stirling Motor in it. I hope this is possible. I'm trying to decide which type of engine would be best and easiest to build. I would also like to build a water cooler (with pump) to cool the proper side of the engine to make it run faster.
Has anyone on here tried to use one of these to power a boat? I have seen one on Youtube, but it was a canoe. It looked like it works, but slowly. Speed is not an issue. I want to be able to use it on a small pond and be able to go a little faster than a trolling motor, but not neccasarily as fast as an outboard.
Thanks in advance for any imput. Scott

[Ian S C]

Scott, Have a look at Andy Ross's motors, his Ross Yoke motors are very compact, I'v built one with a 35mm bore, and 20mm stroke, unpressurised it delivers 5watts, I intend to build one with 50mm bore and 30mm stroke. If you don't like the Ross Yoke, an Alpha motor in a V is a good compact type, these motors have two power pistons, one hot, and one cold. There should be no problem with water cooling, preferably it would be fresh water.
I'm gathering bits at the moment to make a motor for a model boat, as yet the hull is undesided, some thing roomy, about 500mm long, may be a little more.
There are a number of boats in the UK, they have had reggattas on the Thames, there was a sit on the web with photos etc. Ian S C

[hermanpwillis]

I might be in a little over my head then! If you all with your experience in this haven't been able to do it makes me think that I won't be able to achieve it in my two car garage. hhmmmmm.......
So, (I should research this I know) what is it that makes these engines more powerful? What gets in their way of that? I think that being able to produce extreme temperature differences would help, but what else? Better sealing? Thanks for your patience, Scott

[vile_fly]

Well, I don't know about it being more powerful, just more efficient. Power and efficiency never quite go hand in hand, even with gasoline engines. From what I've read, the efficiency of the regenerator is first a design consideration while keeping dead air space down. This is harder than it looks. Next, the cooling system must be optimised, but with an entire lake at your disposal, that should not be too big a problem with an open circuit cooling system. Burning a clean fuel keeps the heater side from clogging up with soot. Making the heater survive in a moist environment may be the biggest issue you have.
An optimal regenerator would be a porous metal displacer piston. I just can't get anyone in that market to acknowledge me as a customer. For a small hobby engine, a sintered stainless fuel filter can be used. I am still working on the v-twin stirling engine, but am not even close to being done.
Pressurizing the engine is probably going to be a must in your application, so sealing will be an issue for you. My v-twin is definitely going to be pressurized.