ORIGINAL: freeair
Guys, i have a new fibreglass fuselage of the Extra 300L which is designed for gas engines of 50 to 80 cc,s . the plan states no right thrust to be added when mounting the engine but when i measured the fuse it has left thrust built in plus the fin also has abit of left and not dead straight ahead. i thought normally right thrust is built in but not left , any help ? thanks.
The left angle on the fin makes sense to me. A lot of full scale airplanes have the fin angled a few degrees to the left, to line up with the spiraling slipstream from the prop. Normally this slipstream spirals down under the fuse and back up and over the left side of the fuse, striking the fin, causing the tail to be forced to the right, hence the nose to the left. A little left angle on the fin will eliminate this force. Model designers build in right thrust for the same reason, as the angle of the slipstream misses the fin. The left thrust is a mystery to me. Are you sure you didn't measure that left thrust while the fuse was upside down?............sorry!!
Lm