Three Cylinder Radial Steam Engine

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Hi Guys

I'd like to thank you all for your real nice comments. th_wav

As I said it was a real enjoyable project, in fact its knocked my plan to get on with my loco build off target a bit, it was the redesign work with the loco lubricator and water pump that prompted me to make the three cylinder, it reminded me how much I enjoy design and development work. So I've got a bit of shop maintenance work to do and a bit of tooling to make, and I want to finish off the part finished elbow engine to raise a bit of shop cash, then I'm seriously considering doing another small engine build, I've seen a small Grasshopper Engine at the Manchester Museum of Science and Industry that's just crying out to be modeled.

I've attached a pdf file thats got all four drawing sheets on one file.

Thanks again


View attachment PottyThreeCylinder.pdf
Hi Chaps
it going to be based on two design of model radial steam engines, I'm going to try and take what I think are the best parts in terms of good design and ease of manufacture from these two designs, plus a bit of bling so that they represent an aircraft engine (cooling fins on the cylinders)

The two design I'm going to work with are:-

The Cygnet Royal by Edgar T Westbury, I got my drawing free from Model Engineer but you can buy them from I understand that you can buy a set of castings for this design but I'm going to use bar stock.

Elmers Radial Engine drawings are available on John Tom>

Hi Stew, I've rad through this thread with interest, and will no doubt learn much more from it as I proceed to build. I have some basic design questions.
1. What did you think were the "best parts in terms of good design" in each?
2. Do you still think so?
3. Can you outline the way the rotary valve works, and give your assessment of how well it works?