topper5

My Feedback: (12)

hello i could use some help! recently bought a christen eagle 65" wing, i powered it with a DA-50, i got it all together, balanced, went out for it's maiden flight and wrecked, here is what happened, at about half throttle the tail rotated up i eased back on the elevator stick, and it started to climb and i mean climb straight up! i had to give it allot of down for level flight, when i would reach for the trim straight up it went again, after about 4 minutes of this the motor died and it wasn't a cool dead stick,. its now back flying but with heavy down elevator trim.
the horizontal stab and bottom wing are spec at 0 degrees, and the top was at 1 degree positive, the motor is at 2 degrease down and 2 degrease to the right.
last night i moved the the top wing to 0 degrease incident, i went and flew it today and it's still flying with a tail heavy attitude, but tail heavy its not after the wreak i moved all the battery's forward.
the mfg told me it was the horizontal stab, top wing, or the motor incident, one of them were off, there not except for the top wing witch i moved to 0 witch did'nt help a bit.
a master builder I'm not.
maybe one of you can help me to understand my problem better.

BankYank

My Feedback: (63)

Im no expert but from your post it sounds tail heavy to me. I would try changing the COG forward.
Pat

bhole74

Did it try to pull a loop or just pull up then neutralize? If it pulls a loop, it is an incidence problem, if the latter, a balance problem.

topper5

My Feedback: (12)

you r right bankyank it dose sound tail heavy, but iv got two degrease nose down on the incident meter, after it crashed i felt the same way and moved all three batteries from the cg to the nose, i try-ed a flat spin with it yesterday and it looked like a dead duck falling from the sky, it is defiantly nose heavy.

topper5

My Feedback: (12)

in reply to bhole74 it pulled straight up and neutralized, but i can't think its a balance problem because as i stated before on pre flight it balanced just a little nose heavy, after the crash i put all three batteries in the nose and it didn't help the flight much at all, the plane right know weights 16.5lb,

bhole74

How does it fly once you trim it out with down elevator? Does it climb or drop with different throttle settings? Does it try to balloon on landing? How about inverted flight, how much down is needed or does it still climb?

topper5

My Feedback: (12)

yes pitch changes with throttle but not as bad as it did before i set the top wing to 0 incident, the landings seem to be OK but with the down trim iv got when i get that slow the nose wonts to drop so i have to feather the stick back, and inverted flight it seems to need just a pinch more down for level flight.

Newc

I would move the CG forward an inch and see what the results were. It may well be that you are 'balanced properly' according to the plans and your incidence meter, but the plans and/or the incidence meter could still be wrong for your plane.

mscic-RCU

My Feedback: (6)

Typically a plane with an incident problem will change pitch with throttle changes. Tail heavy planes are very sensitive to elevator changes and will "porpoise" between nose down and nose up. I think you have an incident problem. Another test is gain altitude (probably not a problem at this point) and cut the power back to idle and see how she flies. If it is a tail heavy condition, the elevator will still be sensitive. If it flies normally with out the tail dropping out it is more than likely an incident problem. Try setting the top wing -1 degrees and make sure the stab is 0 degrees and the bottom wing is 0 degrees. I had a Christen Eagle years ago with the same problem, never did work it out.

topper5

My Feedback: (12)

thanks mscic-RCU i guess one more degrees down is Worth a shot and ill try that next, but first i'v put a 1mm washer between the motor and the stand off's at the top, witch now gives me 3 degrees down on the motor now instead of the spec 2 degrees, most people are flying this bird with a 150-180 4 stroke and they don't seem to have the problem that I'm having with the DA-50, but i have yet to here from some one with a christen eagle matched with the DA-50.
so as soon as i get a chance (some time this week) ill try the setup iv got now, witch is both wings and the stab set at 0 degrees and the motor at -3 degrees...

topper5

My Feedback: (12)

3 degrees down still is not enough but it looks like a step in the right direction, now I'm wondering if the standard 2 degrees down and right is just a good place to start, or maybe its just me and this particular set up

Newc

I'll bet that your CG is still too far back. You didn't move it forward, did you?

topper5

My Feedback: (12)

NEWC no i didn't move it back, i sent you a pm please read it and get back with me.