RE: sig 1/4 scale cub Engine thrust Q's
Forget all these experts with their "I could have..." "I can't imagine........" "It looks like......" and similar opinions. These armchair experts are speculating only, never having operated that plane. Everyone has an opinion about how it must be to avoid total failure, especially those who have never actually done it.
I built, according to plan and flew a Sig 1/4 size clipped wing Cub for many hundreds of successful flights over a more than 20 year period on both wheels and floats. I flew it in both Canada and the USA. I flew it on numerous lakes and rivers and at numerous fields and airports, including off field ops on a couple of cross country runs. I flew it on calm days and others when the wind just about tore the windsock off its pole.
Build the plane as the instructions show. Use an engine more or less in the suggested size range. Whatever thrust is built in as per the plans is all that you need. Period.
Mine flew behind an inverted, fully cowled OS 1.08 and Slimline inverted muffler, swinging a Zinger wood 15-8 prop without any engine problems.
End of story on thrust angles for that plane.