srp55

My Feedback: (54)

Gentlemen I have a Pilot SBACH 26% with a DLE 30, I have the plane balanced slighly nose heavy for my first flights. On my first flightafter trimming it out I noticed the plane started toclimb when I decreased throttle to land. Iincreased throttle took the plane up and verified that when the throttle is cut down to a 1/4 the plane climbs.A senoir pilot/instructer checked the plane over as well as the radio no mixing of servos was found or any other apparent radio issues. I checked the thrust line by leveling the fuz and checking the thrust lineat the propeller hubusing a 6" levelthe bubble was between the lines indicating0thrust. Any suggestions?????

Scar

My Feedback: (3)

Add a half degree up thrust & recheck.

Let us know how that works out.

Best wishes,
Dave Olson

speedracerntrixie

My Feedback: (29)

Now that you have verified the thrust angle, check the stab and wing. I always set up my aerobatic airplanes with zero on the stab and .5 degree positive on the wing. For a 30cc airplane this will be about the 1/16" trailing edge low or close to the thickness of the trailing edge. Verify these measurements and try again. I'm curious how you determined it is nose heavy? Here are a couple more things to try. Fly a 45 degree uplune and half roll. See what the airplane does hands off. If it steepens the upline or maintains, it is tail heavy. What you are looking for is a gradual arc to inverted level. Should take about 5 seconds. The second in knife edge. If the airplane tucks to the gear more then just slightly it's an indication you are tail heavy. I will only adjust thrust angle as needed for true uplines. A little up or down thrust has little to no effect level flight.


I'm suspecting that you are actually a bit tail heavy but will know more after you measure the whole airplane and report back.

Gray Beard

My Feedback: (-1)

That is usually a sign of too much engine down thrust but it can also be incidence and CG. When I set up a plane I put no engine thrust in them at all until I'm doing flight trim testing and see how the plane acts in flight. Most of the time they require a little right thrust but more often then not no down thrust. You can pull up a trim chart from the AMA pattern web site to help figure out what your plane is telling you.

dbacque

My Feedback: (3)

Could be thrust line, could be incidence. It depends on if you mean that it trims differently at different speeds or if you mean it trims differently at the same speed with different throttle settings.

To determine for sure if it is thrust line do the following:

Trim the plane out for full throttle straight and level flight. Then in a full speed level pass, chop the throttle to idle and observe the results. If the plane immediately climbs you have too much down thrust. If the plane continues level and doesn't climb until it slows down considerably then it is probably an incidence issue.

Dave

jetmech05

I was flying a friends airplane the other day and had the exact same issue....he had a mix in it, I can't remember what it was....go back and double checks all your mixes.
I have a Pilot 50CC Yak that required the engine box to be cut before installing the fire wal. Is it the same with the Sbach? if so double check your angle