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Old 08-02-2005, 11:22 AM
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bob27s
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Default RE: Predator Misalignment

Is it rolling left constantly, or does it tend to fly somewhat straight but just banked/sideways or in a yaw ?

A roll is caused by a twist in the wing, or is often do to not properly aligning the two wing halves when joining them. At speed, a very tiny bit of twist in the wings will create a large amount of roll. Faster you go, the worse the roll gets.

The Predator rudder function is pretty much a pure yaw - very slight roll couple. A slightly misaligned V-tail (rudder) trim would not tend to induce a heavy roll. But if it is anything close to 'looking correct' it would not cause a condition that was beyond the range of basic trims... you would notice more of a problem in the turns. If the entire V-stab is indeed rotated a full 1/2" from the cradle, yeah..... that might cause some serious yaw.

You noted you had to hold aileron in it to keep it level. Do you notice it needs more trim when going faster, rather than at landing speed ?

Mount the wing on the fuselage. Lay it flat on the bench. Measure the distance to the LE and TE of both wings at the tip.

Re-measure other items as combatpigg noted.

Also, just on a hunch, measure the wing itself. Make sure it is centered (ie, both panels are the same size)

Im not sure where any of the more recent bad press came from on the Predator. The first batch were a mess, but that was a few years ago. Darrol Cady and a host of others worked with Lanier to improve the plane quite a bit. The planes sold for the past 2 years have been very good quality, and the 4 I built were all straight right from the box.

Bob