thank you very much for the answer...
I m flying an heavy curare equipped with an ys 60 fr, running at about 15000 rpm and an 11/7.
That change the plane, as it is really ballistic, and flies straight, due to the speed...
the same plane has flown with an os 61 sf pump, and, the speed is a lot less, the "big" 12/10 prop induce a lot of gyroscopic and torque effect, does not fly the same as it was in the beginning of the eighties...

an electric classic pattern sounds a bit a shame...

On the other side, electric propulsion has made so much progress, it could be a pity to do no use it...

Main thing for a classic, go ballistic!