How to fix a bad left hand snap


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cccdad
Posts: 37
Joined: Wed Oct 11, 2006 8:21 pm
Location: USA

How to fix a bad left hand snap

Post by cccdad »

I just built a 2548 Hat trick p51. It does not fly to bad but it has a bad left snap when you crank in the elevator. It makes loops look like immelmans and left hand turns want to snap in the dirt. CG is at 3.5 inches from the leading edge (recomended spot)I just checked all my incidences and took out about 4 degrees of down thrust to make the wing/ HS and motor at 0 incidence with no help. I have tried refex in the alierons to no help. My next step was maybe to add right thrust. Any other ideas would help. Building for 2548 is beating me up more than the contests.
montague
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Post by montague »

Well, remember that 2548 planes don't turn as tightly as any other class of combat plane. So you might just be asking too much. Try reducing the elevator.

If it always goes left, and goes down from a left turn and up from a right turn, then check the lateral balance, you may have a heavy wing.

If the balance is on, check for warps in the vertical tail, there's a good chance you have some "left rudder trim" in the tail. You can often fix or reduce this kind of thing by twisting the tail a bit to add some rudder in the opposite direciton. I sometimes put a bit of music wire in the tail to allow me to put in a bend and keep it there.
cccdad
Posts: 37
Joined: Wed Oct 11, 2006 8:21 pm
Location: USA

Post by cccdad »

The left bend in the coroplast tail seems to be a prime suspect. No matter how straight I try to make it as soon as the coro sits in the heat of the sun or truck it usually takes on an unexpected bend. I'm going to try the music wire and let you know.
cccdad
Posts: 37
Joined: Wed Oct 11, 2006 8:21 pm
Location: USA

Post by cccdad »

Tried the music wire yesterday. It helped alot that the snap is "managable" but still there and consistent to the left. I may go so far to put a washer under the motor for a little right thrust.
montague
Posts: 1639
Joined: Wed Feb 27, 2002 3:24 pm
Location: Maryland
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Post by montague »

Yep, or bend the tail to the right with the wire to hold the right rudder. Also check the balance as well, if you have multiple things going on, you can really get a mess.
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