Investigation of Discrepancies between Flight-Measured and Calculated F- 80A Derivatives and Responses Including a Study of Aeroelastic Effects
CORNELL AERONAUTICAL LAB INC BUFFALO NY
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Studies have been made to determine if discrepancies existing between calculated and measured tail loads, responses, and derivatives, as obtained for the F-80A, can be eliminated or explained. These discrepancies were evidenced as 1 a tail load smaller than that predicted, 2 the measured aerodynamic stiffness being significantly greater than that indicated by wind tunnel tests, and 3 an unreasonably large value of stabilizer effectiveness being obtained in the analysis of the flight data. Certain of these results indicated that investigations should be made to establish the manner in which aeroelasticity and unsteady flow aerodynamics influence the tail loads and rigid body response of the F-80A airplane. It was found that a the failure of measured tail loads to agree with calculations is primarily due to an error in measurement due to limitations in strain gage location, b the effect of aeroelasticity is small and not of a dynamic nature, c the lack of agreement between predicted and measured responses at low Mach numbers is due to prediction being based on a wind tunnel evaluation of tail-off static stability which was different from that obtained in flight, and d the stabilizer effectiveness and downwash cannot be accurately evaluated unless the tail-off damping in pitch is determined.
- Attack and Fighter Aircraft