Light-Weight Inflatable Hypersonic Drag Device for Planetary Entry”, Paper at the Association Aeronautique de France Conf. at

The author has studied inflatable drag devices (ballute = balloon + parachute) for deceleration in the atmosphere of Venus, for both direct aerocapture and for entry from circular orbit. The studies indicate that ballutes made of thin materials capable of temperatures of about 500 C allow an entry system mass that is, for both aerocapture and entry, less than with the conventional entry body. For aerocapture the exit conditions are controlled by measuring the velocity loss and releasing the ballute when the desired exit conditions are indicated. A development program is necessary to explore the ballute shapes and changes in flight and to mitigate possible instabilities. To design an entry vehicle using a ballute the designer takes the vacuum orbiter or the lander as it is on the surface, chooses one surface to attach the ballute, and places an MLI blanket on the other end. PRIOR BALLUTE STUDIES Ballutes seem to have been invented in the forties and fifies to reduce the ground impact speed of empty sounding rockets or rocket casings. The investigators probably discovered that the mass of a ballute, inflated at high altitude, to slow a returning high altitude sounding rocke