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I only build monoplanes with clean lines, and try to build them all to the same wing loading. Recent models weigh 35 - 38 grams and have wingspans of 25 - 31 inches. By doing this I can use the same P/D props and the same rubber motors. Usually I use 4 strands of 1/8" tan II and cut the length according to the weight of the model. I also use the same initial adjustments on all my models, 3 degrees right, 3 degrees down, 2.5 - 3 degrees positive wing incidence and start the glide tests with zero degrees on the stab. Both wings have a little washout as well (maybe a little more in the left).
I fly all my high wingers and some of my low wingers to the right under power with a right glide. Those low wingers that refuse to groove with a right pattern are trimmed to fly left. The warps in the wings are reversed and the right thrust is reduced to about 1 degree. Otherwise the trim settings are the same. I use a 10% Neemeyer airfoil wing section and a 6% flat bottom stab. I use lifting stabs on all my scale models, even Peanuts, for several reasons. They can be made just as light as flat section but are stronger and more warp resistant. I believe that the lifting section increases what the aerodynamacists call "tail volume". This enables me to use a more rearward CG location and less incidence, which yields less drag and less tendency for the model to loop on the power burst. The props I use on all my scale models are not helical. They have a diameter of 10" and an average pitch of 11". Highest pitch is at 50 - 60% radius with less pitch at root and tip. I also use a chart tape turbulator on the blades. I use such a low pitch because these props work better with the skimpy 15% motors required in New England competition. I was frightened of the wing on my new Reggiane 2005 because it is similar to the Spitfire wing, which seems to be hard to trim. However, the Reggiane has a lower thrust line which I think adds to the stability of a low winger ( Al "Gray-Hawk" Lawton says the same about his geat flying Ki.61 design...Ed.) I was surprised that it flew right off the drawing board in a nice right circle with 450 hand winds. In my opinion, the Reggiane 2005, the Fiat G.55, and the Macchi 202/205 have as good or better potential as models than any other WW II subjects. I would not consider building a scale model that did not have the potential to fly in the two minute range. Originally published in "Tailspin" the journal of the New England Flying Aces, 24th FAC Squadron. |