REOUIREMENTS FOR PARACHUTES OF GLIDER RECOVERY AND PILOT RESCUE SYSTEMS

Abstract

The German Federal Ministry of Transport (BMV) commissioned the Fachhochschule Aachen (F.H.A.) to investigate the fundamentals of glider parachute recovery systems (GPRS). The final report was completed in April, 1994 but an overview of the whole program had already been presented in Borlange. The present paper takes a closer look at parachute characteristics and attachment points, as well as bridles and risers, in connection with their influence on the system's dynamic stability. It should be read in conjunction with, and is supplementary to an earlier study. Glider parachute recovery systems are feasible. The parachute should be deployed actively by a mortar or a rocket to let it go well over the tail unit. The opening peak force must be reduced by reefing to prevent the glider from disintegration and tuming over. For a successful rescue the GPRS requires a minimum height of about 180 m (600 ft) at level flight and even more at higher dive angles. A properly designed reefing phase adds only a minor height loss. A long three line bridle connecting the glider to the parachute at about -30 degrees nosedown angle assures moderate oscillation and satisfactory ground impact behavior. At a bridle length of one wingspan or more, the parachute stays almost clear of the forebody wake. This minimizes the drag loss of the parachute system.