Design and Testing of a Collapsible Drogue Parachute for the X-37 Vehicle

This paper describes the development and testing of a collapsible drogue parachute design, which was required for the testing of NASA’s X-37 Approach and Landing Test Vehicle (ALTV) from the B-52 H aircraft. The ALTV, which has a relatively low drop weight of 7000 lbs. and an L/D in excess of 4.4 at the time of release from the B-52, also has completely autonomous control authority during the test flights, which, in the event of a software failure, could result in re-contact of the ALTV and the B-52 after release. To eliminate the possibility of re-contact, several mitigation strategies were investigated. The strategy selected involved deploying a drogue parachute from the ALTV prior to release from the B-52, and then releasing the drogue from the ALTV a few seconds after the ALTV separates from the B-52. However, due to the high altitude at which the drogue is released, the predominant wind direction, and the close proximity of an air corridor of a major commercial airport, the drogue was required to collapse after release to minimize its drift potential. Since the drogue parachute required the use of a swivel, the collapse mechanism chosen was a silicone band attached at the drogue skirt. While the chute was attached to the ALTV, the high aerodynamic loading would cause the band to stretch to the skirt diameter, causing only negligible drag loss, but would retract when the drogue was released, causing the drogue to collapse and fall rapidly to the ground. Ground testing demonstrated that the design worked, but the program was cancelled prior to flight testing with the B-52.