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Building Tips and technical articles. => 1/2 A building. => Topic started by: Tim Wescott on March 06, 2010, 10:50:43 PM
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Da Plane: 20" wing span, 100 squares of area, generous elevator area (the top view looks like someone left a Nobler stallion with a Ringmaster mare).
The leadouts are about 1/2" apart, and about 1-1/2 inches back from the leading edge, a good 1/2 inch back from the CG. The plane has very little side area, about 1/8" rudder deflection, very little 'out' thrust on the engine, and a nickel on the outboard tip for balance (I didn't have any pennies).
In level flight and mild maneuvers the line tension is OK if not stellar, but on sharp maneuvers it really loses line tension. It does have an engine sag problem which may be contributing, but it seems to lose tension even when the engine manages to stay strong through a maneuver.
Any suggestions on what I should be looking for or trying? I'm thinking of maybe having someone watching the thing when I pull up sharply, to see if it's rolling in, but that's about as far as I go.
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You don't say how long your lines are. Also I think leadouts may be too far back. Tip weight can be determined by having someone hold the handle with the lines attached. You hold the plane by the prop shaft(or center of nose of plane) and the center at the tail. If plane rolls in you need more tip weight. H^^
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... To Doc's suggestion, but before you go to the field...
Get an empty reel (spool, whatever) the same as the one with your flying lines on it.
Set the model on its back on something soft (so's not to scuff the finish).
Put your reel (spool, whatever) halfway out from the fuselage on the inboard wing panel. Without handle but with any line clips... the wing rocks down, right?
Put the empty (whatever) the same distance out on the outboard wing. With the same number and type of line clips.
Add tipweight until the model about balances - i.e., neither wing panel is detectably heavier...
What this, and Doc's method, does is put half the line weight on the inboard tip. Full line weight at half distance is the same as half the weight at full distance. We end up with an imitation of the weights in flight, where we support half the line weight, and the model supports the other half at the leadout guides. (Not technically correct at higher line angles, but a good starting point.)
This is usually only a starting point, but a decent one. Each model is different, and many may need a bit further tweaking as you get used to flying it.
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Have someone watch your plane when you do a hard corner. If the outboard tip drops, you have too much tip weight, if it lifts, you have too little. Any mechanical test on the ground does not compare to what happens in the air. Flying is the ONLY test that counts. As far as leadout location, for first ground setup ( I know, I know), hang the plane by the leadouts and the fuselage should be nose low by about 5 degrees. THEN fly it and look at the wheels. You should only see one! Figure out whether the inboard wheel is forward or back and adjust until they are in line to your eye. One final adjustment is to sight across the top, then bottom of your handle. The plane should be flying in line with those references, not above or below.
If you do all that and you have differences with inside and outside corners, let me know and we will start a whole new thread... S?P