During alpha-sweep flight testing of the short take-off and landing (STOL) experimental aircraft ASKA, a buffet occurred earlier than expected, as well as large airframe vibrations, both of which contributed to preventing the high angle of attack portion of alpha-sweep testing from being conducted. Wind tunnel tests were subsequently performed in order to delay the onset of the wind buffet that prevented the performance of this flight test, and also to determine effective aerodynamic means to alleviate the buffet's strength. Results confirmed that both triangular fences fitted to the side of the nacelle and a drooped nose on the leading edge between the nacelles were most effective. These buffet countermeasures were then applied on ASKA and flight tests were conducted. It was found that the onset of the buffet was delayed and the vibration frequency of the airframe was reduced. This allowed the alpha-sweep testing to be safely carried out at higher angles of attack; hence enabling the initial objective to be achieved.
Wind Tunnel Investigation to Determine Buffet Countermeasures for STOL Aircraft alpha-Sweep Flight Testing
1991
50 pages
Report
No indication
English