Hi All,

Does anyone know a way of calculating the right engine to fit to a new design? []

There must be a formula I can use to at least give a guide to the right engine size.

Thanks

Nope.

It is a lot of experience and some rules of thumb, but there is no magic formula because the question is too complicated. You need to consider the model size, wing area, AUW, flight envelope (unlimited 3D or gentle scale flying) and more to come up with a starting point and then you refine those initial guesses as you work through to the final design.


Mark

some of the guide lines you can look at kits or other plans of the same deminsions and see what engines are recommended.
I use these as a guide
weight abot 1 pound .049 area 100-200 sq in
2 pounds .10 area 200-300 sq in
3 pounds .15 250-350 sq in
4 pounds .20-.25 350-425 sq in
5 pound .35-.40 .425-550 sq in
6 pounds .50-.61 550-650 sq in
of course these are sport/aerobatic non 3d guides.scale would be higher weights with the same engine,what size are you thinking of?