Burnelli UB-14

[Jamblor]

That's a really cool looking plane, I'm sorry it didn't fly
I hope you can manage to fix it and get it back up in the air.
Like the others, I too believe there is a CG issue.

Although I would like to propose another possibility. Is it possible that there is too much power from the two motors? At high throttle could it be that the motors are pushing so much air that it makes it what to hover vertically?

 

[FlyingMonkey]

Eagle, the Burnelli will fly awesome... once you get your CG correct. It should be balanced perfect with your fingers under that spar. You're going to have to find a way to get more weight forward of the CG point. The clear giveaway is that it goes full nose up once it's in the air.

You might have to move the servos to the front of the plane. Do whatever you can to reduce the weight to the rear of the wing.

Once it balances, it should fly just fine.

 

[quorneng]

Jamblor
Too much power?
Even simple model planes can usually cope with thrust equal to weight or even more so if you really had too much power it would either climb vertically or simply complete a loop from launch, neither of which it did.

It is a balance point issue. Until it is moved forward sufficiently it will not fly properly.

 

[eagle4]

after moving everything forwards, as far as i can get them, and adding some extra bracing to the front, i've managed to move the cg about 1cm, and it actually feels good. i have done some brief throw and catches of the plane and it doesnt have any pitching tendancies, ( i tried it before doing my repaires and it definately had a nose up tendancy) I moved the rear servo fowards into the fuselage, and used a wire for the elevator, i fear i may get too much slop, but i am trying to minimise it. I am contemplating extending the elevator to give me a bit more surface area back there incase i need it. not sure when i'll get a chance to get it in the air next, but we'll see.

 

[eagle4]

Well, its been a while, but I finally got a chance to take my Burnelli UB-14 out for a re-maiden. I had the battery right up against the nose, i moved everything as far forward as possible, even removed the elevator servo from the tail and moved it quite forward and just used a long pushrod to access the elevator. I managed to move the cg forward about 1-2cm infront of the spar. so right at the leading edge of the wing tip.

Here is the video for its flight.

 

[earthsciteach]

Cool! It looks like a decent flyer! She certainly does not lack power.