ORIGINAL: Tony Hallo
Yea I hear what you're saying but two perfect flights and then everthing goes south without warning? Runs good on the ground but not it the air? Things are not adding up.
Consider the positioning of the diaphragm pulse opening. If it's facing a forward or nearly forward orientation it will see little impact, or compressibility, pressure on the ground. It will be subjected to quite a bit more in forward flight. Perhaps more than it can compensate for.
Carbs in anything can be working fine today and not work tomorrow. It's called wear and when they have worn enough they cease functioning as they should. Accellerator pumps were really good for that.