Dream Chaser receives CCDev-2 green light from NASA

by Chris Bergin

As had been expected, Sierra Nevada Corporation’s Dream Chaser ETA (Engineering Test Article) spacecraft successfully passed the final NASA Commercial Crew Development Round 2 (CCDev-2) milestone requirement, despite her tumble at the end of what was an impressive debut free flight in October.

Dream Chaser Progress:

One of the three main contenders to regain American independence for domestic crewed launch capability, Dream Chaser stands alone as the only lifting body design that has the capability to land on an airstrip.

She is in competition with two capsules, namely SpaceX’s Dragon and Boeing’s CST-100, under the funded Commercial Crew Program (CCP) drive to remove the reliance on the Russian Soyuz as the only means of crewed transportation into space for NASA astronauts heading to the International Space Station (ISS).

Although a painful downselect may take place in 2014, all three cotentenders – along with the wildcard Blue Origin option – are making good progress in their drive to be certified to transport American astronauts, a domestic capability lost since the final mission of the Space Shuttle Program (SSP), when Atlantis landed to conclude her STS-135 mission.

Z7There’s a large amount of synergy between Dream Chaser and her since-retired Aunties, with the SNC vehicle often described as a “baby orbiter” by nature of her design and appearance.

However, their cross range capability and ability to glide into a runway is a tactical advantage, thanks to their lifting body designs, allowing for astronauts and downmass cargo to roll to a stop on the end of a preselected landing strip.

At the same time, being able to safely re-enter, glide to the runway and land safely is a challenge in itself, with the Dream Chaser ETA having to earn her wings when she was cut loose from her safety line during the October test.

Z779She had been in the air before – both in the open air of her Colorado base, and again several times during her Californian working holiday at the Dryden Flight Research Center (DFRC).

These Captive Carry tests allowed SNC and NASA engineers to check out how the vehicle performed with the wind in her hair, as the practise runs mimicked the final approach to the runway.

However, the real test would come when the harness connected to noisy partner was severed, allowing her to fly on her own for the first time.

Z4On October, 26 – at 11:05am local time – and after several final passes over the test range, the command of “release” was given over the loop.

The ETA began her flight at 12,500 feet, flying for real to prove her design. A failure at this point would have been a serious blow to her career, but it was a real risk, given it had been decades since a vehicle of this nature had been tested.

Following release, the ETA dove into a steep down angle of around 50 degrees in order to pick up speed, before her autonomous flight computer system broke the dive, as her nose started to rise and Dream Chaser began to fly proudly.

Following that key objective, the next 30 seconds involved the ETA refining her approach to the runway in preparation for landing. The vehicle showed no difficulties in the air and smoothly approach to the runway, firing test data back to engineers as she continued towards landing.

Z7Heading towards Runway 22L at Edwards Air Force Base, the ETA flared up her nose and lowered her air speed to 160 knots, mirroring the familiar final segment of flight observed by the Shuttle orbiters.

Sinking towards the landing strip, the ETA then commanded for her gear to deploy, following data from her onboard ground radar altimeter.

Both the nose skid and the starboard gear deployed as planned. However, the port landing gear door remained closed, later understood to be the result of contamination in the hydraulic fluid used to power the system.

Notably, the landing gear were donated parts from a fighter jet, as opposed to the actual gear she will eventually conduct missions with in the future.

Z8The ETA had no option but to continue towards landing, aiming down the centerline of the runway, touching down on her right MLG.

Despite holding her form during the opening seconds of touchdown, she began to lean to the left, as the weight on her port side found there was nothing but air between the structure and the runway.

As her port airframe touched the runway, she began to skid off the strip, heading into the sandy surroundings of Runway 22L, before the vehicle structure dug into the ground, causing her to go for a tumble, surrounded by dust, debris and her imitation Thermal Protection System (TPS) tiles flying off in all directions. She came to rest in the upright position.

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Thankfully, the damage was not as bad as that feared by those observing the landing, with her scars mainly of the cosmetic nature, as opposed to structural. It was later revealed that had there been a crew on board, they would have “walked away” from the accident.

While that provided SNC with an unscheduled test of Dream Chaser’s strength during such an incident, the focus was soon switched back towards what were numerous successes during her first free flight.

The objective of the test milestone under CCDev-2 focused on the ability for Dream Chaser to fly and approach the runway. As such, SNC were confident NASA managers would provide a green light to class the test as complete.

Although it took over a month, that confirmation recently arrived, allowing for SNC to tick off the remaining box on their CCDev-2 requirements.

Z9“SNC is pleased to begin flight testing and to have successfully completed the CCDev2 agreement,” said Mark Sirangelo, corporate vice president and head of SNC’s Space Systems.

“Having the Dream Chaser flight exceed our expectations on its first autonomous flight was an extraordinary accomplishment for SNC, its team of industry, government and university partners and all those who worked on the NASA heritage HL-20.”

In reviewing the performance of the ETA, all expected trajectory and flight data – including the nominal glide slope and other aerodynamic data – were successfully demonstrated and collected in-flight. The vehicle’s performance during flight exceeded predictions and requirements.

Z66“A spacecraft that lands on runways provides unique benefits for commercial spaceflight, but also presents unique development challenges,” added Phil McAlister, NASA’s director of Commercial Spaceflight Development.

“This flight of the Dream Chaser’s full-scale atmospheric flight test vehicle considerably improves confidence in the Dream Chaser’s design and Sierra Nevada Corporation’s ability to overcome engineering development challenges.”

The confirmation of the successful milestone came after extensive post-flight analysis by NASA, resulting in SNC receiving the full award value.

“We thank NASA for the tremendous support we have received over the life of the CCDev2 agreement and look forward to continuing our strong working relationship in building the next-generation crew transportation vehicle,” added Mr. Sirangelo.

“Our goal is to restore America’s leadership in human spaceflight and completing CCDev2 was a critical step along that path.”

SNC now move into an busy period of pressing towards their upcoming CCiCAP milestones, as they press ahead into what could be a 2016 flight into space via a future Dream Chaser.

Dream Chaser has also attracted interest from Europe – namely the Germany space agency, DLR – in using the vehicle in several capacities, with a future article set to outline the vehicle’s American and overseas aspirations.

(Images via SNC, NASA and L2)

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