Velocity

2014

NovAtel's Annual Journal of GNSS Technology Solutions and Innovation

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CPAS Orion velocity 2014 For more Solutions visit http://www.novatel.com 38 air turbulence. All CPAS tests are conducted at the U.S. Army's Yuma Proving Ground in Yuma, Arizona. The most recent tests The tests in January and June, which incorporat- ed a Forward Bay Cover for the first time, proved to be one of the more complex Orion flight-like tests to date. The covers act as a shell that fit over the spacecraft's crew module, protecting Orion during launch, flight and re-entry. When Orion is ready to return from space, the cover must come off before the parachutes can deploy. Twenty parachutes were deployed during the January test—nine were test technique related, while 11 were Orion system parachutes, according to NASA. This test set out to demonstrate how the full Orion parachute system performs and inter- acts during an end-to-end test. The test also dem- onstrated extraction using a modified technique in the reposition and programmer staging. "When the drogue parachutes are deployed on the Orion capsule, that's where the test se- quence begins," Williamson says. "These para- chutes slow the vehicle down to a velocity the main parachutes can handle. At this point, the vehicle is going multiple hundreds of miles an hour. If we just deployed the main parachutes, they would fail. So we slow it down with a smaller set of parachutes first. Once the vehicle is at the right velocity the next step is to deploy the Pilot Parachutes. These smaller parachutes pull the main parachutes out so they can be de- ployed. That's when the main parachutes will slow down the vehicle to the rate below 33 feet per second." Researchers looked at the main parachute's modified reefing stage ratio during this test. The drop test article landed at the speed of 17 mph, as measured from a SPAN-SE receiver. The April 2014 test served as a launch abort simulation. Researchers dropped the test vehicle from a lower altitude—13,000 ft msl—skipping the drogues in the parachute deployment se- quence to ensure the main parachutes can in- flate and decelerate the vehicle, even if the launch abort system activates on the pad. Williamson says they got a full data file and early indications show it worked nominally. Test engineers are working with SPAN-SE data within Google Earth, where they are making a 3D plot of the trajectory of the test vehicle from take-off to landing. Other tests A total of 17 development tests will be completed before the team moves on to qualification test- ing, which is expected to begin in early 2016. The design that was refined and functionally proven will then be tested to qualification requirements levied by the Orion Program. The final CPAS en- gineering development unit test (EDU) is sched- uled for February 2015. "Now we're working out bugs, failing parts of the parachutes to see how they react," William- son says. "In one test we failed one of the three main parachutes to make sure we can still meet the safety of the 33 feet per second descent rate even if one of the main parachutes is missing. When we go into qualification we should have all those tests complete. Then we can focus on the design and proving to the program and safe- ty community that our parachutes meet the de- sign requirement that have been levied upon us." The team has tested various failure modes over the years, including a simulated failure in- volving a skipped second reefing stage on the drogue parachutes resulting in higher para- chute loads, and a failure to deploy one of the three pilot parachutes. CPAS also has exam- ined how the wake, or disturbance of airflow behind the vehicle, from the spacecraft affects the parachute system's performance. "To date we've had great success. Most of our failure cases come out with flying colors," Wil- liamson says. "We do a lot of prep work. Tests can take 6 months or more to develop before we go out to Arizona. For me success means hav- ing a good plan, working that good plan and learning something from it." Orion technology advancements Orion is described as the most advanced, safest spacecraft ever built. It will use advances in propulsion, communications, life support, structural design, navigation and power. A dart-shaped test vehicle that simulates Orion's parachute compartment was used in this 2012 test drop. Engineers wanted to know the maximum pressure Orion's chutes might face as they returned from exploration missions.

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