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Old 09-06-2007 | 11:07 AM
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rmenke
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Default RE: Thrust angles??

patnchris:

Thrust angles are usually built into the firewall at the factory, and are generally like girls. Come in all shapes and sizes, not necessarly correct. Thrust and incidence vary from design to design and preferences including the CG will differ between pilots much the same as the use of dual rates and expo. All these factors will determine how well, or how poorley something will fly. I recently finished a high dollar pattern plane that called for 1/2% positive incidence in the wing and 1/2%negative in the elevator stab. Got a real kick out of ths as I don't thing there are many people in the World able to set up and capable of measuring incidence that close. A typical Robats meeter can get you to around 1-2%, but you need a digital meeters (2) and a flat floor and work bench to make things workable. There is a digital incidence meeter now on the market, you can also buy digital incline meeters from various places, Sears is one, called "Smart Levels" that are accurate to one tenth of one degree. Unfortunately they are around $75.00 each. A very accurate meeter does not do you much good working off a unlevel bench or floor and some device to hold the plane in place so that measurements can be repeated and checked with accuracy. Once you do all this incline/thrust stuff, you then go to the field and trim in the airplane. If your were 100% on the workbench, no trim would be needed. Your better pilots, and top pattern flyers will spend days, weeks or months gertting their ship trimmed. There are elaborate trim proceedures used by the pattern guys that do in the end, improve the flight caracter of their airplanes. Hope this helps. ENJOY