Hi Tom,
I will give Morris a call but he is bound to have a vested interest. I was looking for an unbiased report. I guess I will have to wait a while. At the moment the project is just in my imagination, but I have always loved theRAF Bristol Bulldog biplane from the 1930's. Its a lovery looking machine, but like a Stearman, it hangs all of its cylinders out in the breeze and there are 9 of them. Looking at the tiny pdf on the UMS website the diameter is only 260mm, which at scale size could result in a model of around 80" wingspan. With care I think I could get this under 8 Kg or 17.5 lbs.
Having seen the original Seidel radials perform in the past, they were beautiful things, but not so powerful. So the questions if would the UMS 9 cylinder 115 Gas engine adequately power such a model? Opions welcome.

John