Wing parachutes for recovery from the spin. Part I - General design requirements. Part II - Wake Phenomena.

Abstract

Part I. The suggestion to use parachutes attached near the wing tips for recovery from bad spins is not news, but was considered -before tail parachutes were introduced. With the increasing interest in tailless types it has become necessary to reconsider the wing parachute as a safety device, and wind-tunnel tests have showvn that it can be of powerful assistance. Part II. The wing parachutes of a tailless aircraft prototype failed to open when streamed in an accidental spin. This gave a clue to the existence of a marked wake effect when a parachute is deployed on a tow cable behind a stalled wing. This wake effect is such as greatly to reduce the critical closing speed of the parachute. The effect measured in a wind tunnel diminishes as the cable is lengthened. It is recommended that the cables should be made as long as possible up to one and a half spans in length; here the danger of entanglement becomes real. The centrifugal forces in spinning may also be turned to good account in making the parachutes ride outside the wing wake; for the same reason, attachment at the extreme tip is preferred to attachment inboard.