C-17 airdrop sets record, completes next step for Ares I program
By Kenji Thuloweit, 95th Air Base Wing Public Affairs
/ Published August 31, 2011
EDWARDS AIR FORCE BASE, Calif. -- Though Edwards, along with the rest of the nation, bid farewell to the space shuttle mission, the 418th Flight Test Squadron and NASA took another step toward the future of America's space program and set a record doing it.
An 85,000-pound jumbo drop test vehicle was extracted out of a C-17A at 25,000 feet over the U.S. Army Yuma Proving Ground in Arizona Aug. 24. The JDTV is used to test the parachutes for NASA's Ares I launch vehicle's solid rocket booster.
"These parachutes are intended to be the recovery chutes for the Ares first stage launch vehicle, which is the solid rocket booster that is planned to be the replacement for the space shuttle in terms of the United States having a manned space launch program," said Chris Webber, 418th FLTS Airdrop Testing lead engineer.
The airdrop set a new weight record for the C-17 Globemaster III.
NASA, in conjunction with Alliant Techsystems and the United Space Alliance, is providing a decelerator recovery system for the new five-motor segment solid rocket booster. This recoverable SRB is used in support of the Ares I space launch vehicle and is heavier than the current recoverable space shuttle SRB. The increase in weight requires a larger set of parachutes for deceleration and recovery. Testing must be accomplished in order to validate the design of a new drogue and new main parachutes for the Ares I launch vehicle.
The C-17 airdrop is part of the JDTV phase II test system which is comprised of a JDTV and a carriage extraction system. The CES is the carriage for the JDTV, which is used for transportation, aircraft loading, extraction and reorientation of the jumbo drop test vehicle prior to its release.
Prior to this record 85,000-pound drop, the 418th FLTS has successfully completed 42-, 60-, 70-, and 77,000-pound JDTV Ares I airdrops. The next airdrop is scheduled for spring 2012 and will be with a 90,000-pound JDTV - the final scheduled weight in the testing.
If successful, that scheduled airdrop will be the heaviest airdrop in history for any airframe.
"Every time we do one of these tests it also happens to be a heaviest airdrop weight record for the C-17 Globemaster III," said Webber. "We and our partners at Boeing in Long Beach [Calif.] are responsible for the effects on the aircraft. Between every drop we look at the data and make sure that the instrumentation that is on the critical aircraft structure is staying within load limits and nothing is going to be exceeded and so far, preliminarily, those data are looking like they're within limits and we'll be cleared to go to the final heaviest drop weight."
Webber added preliminary feedback from NASA indicates the parachutes performed as expected. Test pilots on the project have spent hours in the simulator and aircraft training for the drop tests, to include practicing contingencies and malfunctions and performing airdrops to prepare for the dynamic response of the aircraft during the extraction of the test vehicle.
"We had to get several waivers since we operated the aircraft outside the normal tech order limits," said Maj. Eric Bippert, 418th FLTS assistant director of operations and C-17 test pilot.
"For instance, we had to fly 175 knots while usually we're restricted to 145 for heavy equipment drops. We also had a deck angle of seven degrees when it's usually between 3.5 and 5 degrees, so flying this profile was a little different to make sure the load exited correctly."
Engineers with the 418th FLTS have partnered with Boeing to analyze the effects of these heavyweight drops on aircraft ramp structural members and collect data in real time during the drops. Additionally, mission systems engineers have worked hand in hand with Yuma Proving Ground personnel and NASA to develop rigging procedures for the airdrop platform and test vehicle.
"There's a large number of diverse individuals out there that you have to work with between the airdrop shop in Yuma along with all the contractors as well as everyone on the crew. It's a huge team effort and I'm proud to be a part of it," said Bippert.
Both Bippert and Webber remarked how special it was to be a part of this past test.
"It's all very interesting work and frequently it's one of our warfighting commands who need what we test, but in this case we're supporting the space program because we are the only ones who can do these drop tests for them. There's no one else in the world who can do this," said Webber.
Bippert added, "Just to be a part of our nation's advancement into space and to be a part of the C-17 team to do this was really remarkable."