The effects of trailing edge up flap deflection and center of gravity position on aircraft power required and drag

Previous research at the University of Tennessee Space Institute determined the effects of trailing edge up flap deflection on the best range, best endurance and maximum level flight speed. It was thought that a trailing edge up flap deflection would cause a reduction in the induced drag and trim drag and an improvement in the aerodynamic performance parameters discussed above. This study determined that the best range and maximum level flight speed were improved at a trailing edge up flap deflection of four degrees. Previous research did not determine if these improvements were due to a reduction in parasite or induced drag. The primary focus of current research is to determine the cause or causes of this improvement. A secondary focus looked into the variation of the results with movement of the center of gravity. A level flight performance test series was performed on a variable stability North American Aviation Navion. This series tested 0, 2,4, 6, 8 and 10 degrees trailing edge up flap deflections and two e.g. positions. Current research found that the best endurance was improved at a flap deflection of eight degrees for both e.g. positions and the best range and maximum level flight speed were improved at a flap deflection between two and four degrees for the forward e.g. position. The best range and maximum level flight speed were found at a flap deflection of zero degrees for the aft e.g. position. The study also found that the best range and maximum level flight speed results were more closely correlated to the zero lift drag effects. The best endurance was more closely correlated to the induced drag effects. Movement of the center of gravity aft effects the results by increasing the zero lift drag coefficient at two and four degrees trailing edge up flap deflection and increasing Oswald's efficiency factor of the wing throughout the range of flap deflections tested.