While flying my son's 33% Edge 540, I flipped her on her back and she was climbing at about a 15-20 degree angle! With stick in neutral - she flys flat as a table, but inverted she climbs.....so we tried the 'check' for CG (45 degree power dive and cut power) and it just continued without dropping or climbing....

I'm confused, why would this plane fly level upright, climb when inverted (sticks neutralized).....anyone?

Jerry

I doubt if it is too much down thrust. Possible, but not likely. If you are tail heavy you may have trimmed in a lot of down trim and which converts to up when inverted. This might also apply if you don't have your incidences correct, but this is unlikely too, given that most ARF's now days are stone cold accurate on the incidences.
Check how much down trim you have the next time you land and you might go back and re-check your incidences.
Golly, gee, that is a mystery.

Mountain Bob (AKA 3dbob)

Cg is to far rearward. I'm afraid I fly the little electric shockys, and that's the way the plane is set up. Playing with the CG till there is no trim change whether upright or inverted

Thrust line changes don't really do anything -
It is all cg setups the trailing angle of the elevator will change response somewhat but not much.
If--you have really odd geometry on elevator linkage - or have sticky/strange linkage -this also can do funny up/down trim changes.
I have th 33% EDGE by H9 -CG is best in forward range - -I balance models such that a relocation of batts will run cg from one end to other of the recommended CG- then fly and locate battery till it feels good .

I have the same problem with a Royal Curtiss P-6-E hawk. Model was set up per the plans and the first flight was a hand full. I ended up with lots of down elevator trim. I never had any feeling that it was about to stall. First change was to move CG 1/2 inch forward. It still climbed inverted and elevator authority was reduced so that I ran out of elevator on the landing flare. Next tried two washers under rear engine mounting lug to give downthrust. This reduced down elevator trim, but now model would balloon when throttled back and I had to hold down stick on landing approaches. Inverted flight required minimal elevator control. I have reset the thrust line to zero and decided to fly it like this. Perhaps it could be fixed if wing incidences were adjusted, but that would make a mess of the struts and functional rigging. I guess if I want an aerobatic biplane I'll have to get busy and build the Aeromaster kit I have stashed away. The Hawk can just fly around and look pretty. Last weekend I landed a Midwest Super Pitts biplane that the owner was having a bad time with. I tried to trim first and when I went inverted it climbed. It was trimmed well enough to land, so I did and decided that particular plane is HIS PROBLEM!
Chuck

Another way to fix your Curtiss Hawk without changing the flying wires, struts,etc, would be to cut the stab loose and put some positive incidence in it. Preferably, as you say, at 0 incidence with the wing. To bad it's capabilities can't be used.

An easy possible fix is to just change the neautral position of the ailerons, put just a bit of up on both, retrim elevator for level flight and then check the inverted flight for climb or dive. Costs nothing to try and may save extensive structural or equipment remounting modifications. Let us know if this works please. If you have a computer radio the change should be effortless.

Rodney,
Good idea!!! I'll try that but it will be a few days before I can get to the field again.
Thanks,
Chuck

You most probably have a wing/horizontal tail incidence problem. Place the plane upright in a cradle and level the fuselage using the thrust line drawn from the firewall to the tail post. Place a incidence meter such as a Robart unit on the horizonal stab and read the the meter measurement, now do the same thing for the corresponding wing panel. The wing and the stab both should be close to zero. I'll bet the stab is a neagitive number. When inverted the stab will react as up elevator.

I'll check it! Thanks for the suggestion....

Jerry

Move the cg forward!