Hey, does anyone know where the Center of gravity is on a Hangar 9 Extra easy trainer? If not, how would i go about finding the CG on this airplane. The reason i'm asking is because i'm using a different engine than what it came with, and therefore a different weight. Unfortunately, the manual doesnt say either, i guess because its a RTF, and almost completely assembled already. I want to balance this plane before i go and attempt to fly it. I would appreciate any help.
-Jamie

I find it hard to beleive that the manual dosen't tell you where the CG is of that airplane. that's one of the most basic checks you make before you fly! Usually a trainer will balance at the main spar, usually right in front of where the wing LE sheeting ends. Or about 1/3 the chord of the wing. Search the forums and you'll find a LOT of advice about setting CG!

Balance that sucker and fly the wings off it!

Andy

For a trainer, 1/3 is the outer limit I'd personally consider... I like to set trainers up at about 28% and move it back as the comfort level grows.

A warning: Andy's right -- you sure can find a lot of advice about balancing your plane on the forums... Consider the advice about relative positions (like when somebody tells you to put it some portion of the way back the chord length). Unless the measurement came from your particular plane, don't listen to advice about position with respect to the wing spar (like when somebody tells you that most planes balance right at or a quarter inch in front of the spar)... a designer can specify that spar at 25%, 35%, 3" or wherever he wants, and then the builder can MOVE it wherever HE wants... No guarantee of any particular relationship between the spar position and the desired balance point of the plane.

ok, thanks Al , Andy. I will try at 1/3 and see what happens. I dont know why, but trainers always have a tendancy to want to nose up after takeoff, espcecially RTF. Maybe i should keep it back as far as possible.

The climbing tendency could be due to the trainer's flat bottom wing. The faster they move through the air, the more lift they generate and the faster the nose points to the sky.

I like 25% to start off with.

Remember the old saying: "Nose heavy planes fly poorly, tail heavy planes fly once"