Actually, the mfg calls for a .32 to .40 2-stroke, so an OS .46FX would actually already be "overpowered"

So I think an Irvine .53, putting out a 1.7Bhp might be a bit to much... remember this is a very small, light plane.

Anyway, if you decide to build one, let me know !

I already read some articles on structural weakness in the kit, that must be reinforced (for which purpose I will use carbonfiber/epoxy)

The GreatPlanes prototype has an OS.40 LA inside, but this will be underpowered for vertical I'm sure. Apparently even a .46LA doesn't pull it.

So perhaps an OS.40FX or .46FX are good, let's wait and see what SHARADEDGE540 's experiences are...