i decided to stuff an O.S. 91 four stroke in this bird, so this morning i measured the thrust angles and cut the firewall out. marked the fuselage where the firewall needs to go. tomorrow I'll cut out a new firewall
I didn't want the engine sticking way out the nose, plus this engine weighs 7 ounces more than the 40 that came out of it, so shifting weight rearward will help balance things out.
this sets me back on finishing, but if it isn't done right, why do it?