A vortex panel method for calculating aircraft downwash on parachutetrajectories
- Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Parachute system performance issues such as turnover and wake recontact may be influenced by velocities induced by the wake of the delivering aircraft. The magnitude and direction of these aircraft-induced velocities is dependent on the specific delivering aircraft (as characterized by its size, shape, and weight), the aircraft’s speed and flight path (including any maneuvers which it is performing), and the location on the aircraft from which the system is released. In addition, the parachute deployment sequence is of major importance. The most significant effects will tend to occur after parachute deployment since induced velocities from the aircraft may become significant when compared to the velocity of the parachute system. For example, any downwash behind an aircraft will tend to cause a parachute system, which is horizontally deployed, to fly at a more positive angle of attack. As the forward speed of the parachute system decreases after deployment, this induced angle of attack will tend to increase. This effect tends to retard the rate at which the parachute system “turns over” from a horizontal trajectory into a vertical one. On the other hand, a maneuvering aircraft might produce upwash in its wake which would produce an opposite effect. In this case, the turnover rate would be enhanced. Aircraft-induced velocities may also affect the process known as “wake recontact” in which the momentum of the parachute wake causes the wake itself to overtake the parachute. This sometimes causes severe collapse of the canopy such as reported by Spahr and Wolf. Wake recontact may be either hastened or delayed, depending upon the aircraft flight path and the parachute deployment sequence
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 6062561
- Report Number(s):
- SAND-90-2178C; CONF-9104171-7; ON: DE91009764
- Journal Information:
- 11th Aerodynamic Decelerator Systems Technology Conference, Conference: 11. AIAA Aerodynamic Decelerator Systems Technology Conference, San Diego, CA (United States), 9-11 Apr 1991; Related Information: Chapter in the book titled "11th Aerodynamic Decelerator Systems Technology Conference"
- Publisher:
- AIAA
- Country of Publication:
- United States
- Language:
- English
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