Thursday, October 08, 2009

Orion Main Parachute Testing Technique Demonstrated

NASA and engineering support contractors completed a demonstration test of the main parachute test equipment for the Orion crew exploration vehicle Oct. 2 at the U.S. Army’s Yuma Proving Grounds in Yuma, Ariz.

The demonstration is part of a series of tests to support the design and development of the Orion parachute recovery system, which is derived from the system NASA used to recover the Apollo spacecraft.

In August 2008, NASA experienced an anomaly in the test technique when deploying a full-scale Orion boilerplate parachute test vehicle (PTV). To improve the testing technique and prevent such an anomaly from occurring again, NASA is developing “smart” systems to make the extraction of large, oversized payloads from the C-17 aircraft repeatable and creation of the right test conditions more reliable.

For the recent test, a 20,700-pound test vehicle was extracted from a C-130 aircraft at an altitude of 20,500 feet. The test conditions simulated the dynamic environment that the test vehicle experiences when extracted from an aircraft. The new “smart” avionic systems are designed to sense the attitude and pitch rate of the test vehicle and trigger the proper time to release the vehicle from the test platform to begin the parachute test. All of the new avionics worked as planned, recorded the proper release points and the equipment landed safely.

The test vehicle consisted of a nine-foot-wide by 24-foot-long platform with a 16-foot-long weight tub. The tub included a backstop structure to provide a positive angle of attack when the vehicle was descending under the programmer parachute. Honeycomb was built up on the weight tub to simulate the profile and aerodynamics of the actual test vehicle that will be used in later testing. Simulating the aerodynamics of the vehicle is important since that contributes to the pitch motion when the vehicle is extracted from an aircraft.

The next demonstration of the new test equipment is scheduled for November 2009. A third demonstration focused on better understanding the wake effects of the programmer parachute is scheduled for January 2010. Tests for the pilots, drogues and main parachutes are scheduled to begin in late 2010 and continue through 2014.

To gather additional useful data during this demonstration of the testing technique, two Orion main parachutes were deployed with over-inflation control lines to investigate their effects on drag oscillation.

One of the causes of drag oscillation is the “breathing” of the large ring sail parachutes resulting in time-varying drag performance. Better understanding the drag performance will improve the calculations of Orion’s touchdown velocity and the impact loads the vehicle must be designed to sustain. Engineers will study the data collected to see if the design modifications can be used to optimize the main parachute performance.

Orion will carry NASA's next generation of astronauts to the International Space Station and beyond. NASA's Johnson Space Center in Houston manages the Orion Project for the Constellation Program and leads the design and development of the crew exploration vehicle recovery system. The Houston division of Jacobs Technology Inc. in conjunction with Airborne Systems of Santa Ana, Calif. are designing, developing and testing the parachutes in Yuma.