RE: 52cc conversion engine and biplane
After todays game, I should have told you the 20 lb combo would hover like a hummingbird and pull vertical like a rocket.
I've had a 50cc conversion (at least 6 lbs) like your's in a 1/4 scale Extra. It flew very heavy and didn't have much vertical. Been that route. The 50cc engines with mucho grunt like the DA, 3W or ZDZ have small lite-weight crank cases and electric spark in place of the heavy magneto system.