Mortar Deployment Extensibility for the Low Density Supersonic Decelerator Parachute

A pilot ballute deployment planned for use with the Low Density Supersonic Decelerator parachute is shown to be capable of producing canopy initial presentation and inflation conditions functionally equivalent to those encountered in a traditional mortar deployment. This equivalence is critically important as it allows the pilot deployed test results to be extended to a mortar deployment without necessitating the use of a large mortar. In this manner the as-tested parachute can be brought to TRL 6 making it suitable for use in future Mars landed missions. This equivalence is achieved through the use of a full-scale decelerator system with matching flow characteristics and vehicle relative velocities. Most notably, a solution was found that maintains at least some tension in the parachute rigging throughout the deployment process and releases the ballute prior to line stretch such that the parachute extraction from the deployment bag is unaided and proceeds in a manner nearly identical to that expected for a Mars mortar deployment. The pilot ballute is also shown to automatically compensate for the uncertainty in dynamic pressure inherent to the uncontrolled flight of the test vehicle. Hence, the test deployment problem reduces to designing for a minimum ballistic coefficient ratio between the vehicle and the ballute/pack system. The ensuing design is demonstrated to be robust to the expected LDSD deployment environment.