WIND-TUNNEL TESTS OF A SERIES OF 18-FOOT-DIAMETER PARACHUTES WITH EXTENDABLE FLAPS

SUMMARY The performance, stability, and control characte'ristics of a series of parachutes with extendable flaps are presented for a range of free-stream velocities from 20 to 60 feet per second. The tests included the variation of both flap length and flap width. The maximum lift-drag ratio which could be obtained depended upon flap configuration, flap extension, and suspension line length. Aerodynamic data obtained during the tests indicate that the parachutes were statically stable at all values of lift-drag ratio up through the maximum value. Visual observations indicated an increase in dynamic stability as lift-drag ratio increased. INTRODUCTION Conventional parachutes have been used for the recovery of space vehicles, but they provided no control of the glide path and, consequently, no choice of landing site. One means of providing glide-path control is through use of an extendable flap in one side of the canopy. Tests of several flapped parachute configurations were made in the Ames