Aerodynamic Decelerators, The Year in Review,

Aerospace America, December 1998

Copyright c 1998 by the American Institute of Aeronautics and Astronautics, Inc, all rights reserved

The state of the art in aerodynamic decelerator technology has advanced significantly this year. Contributions toward a wide range of applications have been reported from all sectors of government, industry, and academia, from fundamental research through large-scale development.

In the area of planetary exploration, postflight data analysis has confirmed the excellent performance of the NASA/JPL Mars Pathfinder parachute system. A nearly identical system has been built by Pioneer Aerospace for use on the upcoming Mars Surveyor 98 lander. Lockheed Martin Astro- nautics has completed integration of the Stardust comet sample return capsule. This probe will be launched in February 1999 to return seven years later on a two-stage parachute system. Lockheed Martin has teamed with Pioneer Aerospace and Vertigo to develop the next-generation parafoil Mid-Air-Retrieval System, which will be used for the first time on the Genesis solar particle sample return capsule.

Closer to Earth, Irvin Aerospace is developing the landing system for the Kistler Aerospace K-1 reusable launch vehicle. The main parachute test program was concluded with the successful drop of six 156-ft-diam ringsail parachutes (a world record). Drop testing of the drogue and stabilization parachutes will be completed in the near future. Ground impact tests of one-fourth-scale airbags are also nearing completion, and results are being used to calibrate analytical models.

The X-38 performed its first free flight and successful, safe landing under a 5,500-ft2 parafoil at NASA-Dryden in March. The X-38 is a NASA in-house technology demonstration program established to satisfy the International Space Station requirement for a crew return vehicle to replace Soyuz. The successful drop followed extensive testing of the parafoil-based recovery system (from Pioneer Aerospace) using a weighted pallet at Yuma Proving Grounds. Among the objectives achieved were successful deployment of the drogue/parafoil recovery system from the X-38, positive parafoil control authority, and low landing vertical velocities.

Even closer to Earth, the USAF Office of Scientific Research, with the Army Soldier Systems Command (Natick, Mass.), teamed with industry and academia on the New World Vistas Precision Air Delivery program. This basic research program is exploring low-cost technologies to improve high-altitude aerial delivery accuracy. The program is integrating advanced wind sensors and models into a computed aerial release point planning tool from Draper Labs that will be able to communicate with the payload. Decelerator technologies covered include autonomous control of round parachutes (Boeing/Vertigo) and a ballistic low opening cross system from Paranetics and Parks College of St. Louis University.

Natick has teamed with Simula to develop a replacement for the T-10 personnel airdrop system. The new system has dem-onstrated soft landing technology to allow for a faster overall descent with a landing velocity of less than 16 ft/sec. USBI's 30-ft autonomous semirigid wing (successfully drop tested over 100 times) is being scaled up to a 58-ft version (5,000-lb payload), and initial testing of the extraction process has been completed. Na-tick is also conducting research on new parafoil opening and fabrication technologies, and on soft landing technologies. Autonomous parafoil technology is being pursued in several locations, including Natick and Germany.

High-performance computer models that couple the fluid and structural dynamic phenomena of decelerators are being developed by Natick with the Army High-Performance Computing Research Center, the University of Connecticut, and others. Similar efforts are progressing at Sandia, the French ministry of defense, and other facilities. A fully coupled 3D capability has been demonstrated in this area for a wide range of systems. These tools are being validated with wind tunnel testing at Sandia, Parks College of St. Louis University, and others. The goal is to obtain an airdrop "virtual proving ground."

By Richard J. Benney