Sunday, October 27, 2013

It's Not the Fall ...

A computer animation of Dream Chaser operations. Video source: Sierra Nevada Corporation.

The first remotely operated drop test of the Sierra Nevada Dream Chaser ended badly yesterday, when landing gear failed and the vehicle flipped.

According to a Sierra Nevada press release:

The vehicle successfully released from its carrier aircraft, an Erickson Air-Crane helicopter, as planned at approximately 11:10 a.m. Pacific Daylight Time. Following release, the Dream Chaser spacecraft automated flight control system gently steered the vehicle to its intended glide slope. The vehicle adhered to the design flight trajectory throughout the flight profile. Less than a minute later, Dream Chaser smoothly flared and touched down on Edwards Air Force Base’s Runway 22L right on centerline. While there was an anomaly with the left landing gear deployment, the high-quality flight and telemetry data throughout all phases of the approach-and-landing test will allow SNC teams to continue to refine their spacecraft design. SNC and NASA Dryden are currently reviewing the data. As with any space flight test program, there will be anomalies that we can learn from, allowing us to improve our vehicle and accelerate our rate of progress. explained the “anomaly” (ETA means Engineering Test Article):

However, via what is being classed as a mechanical failure of the left landing gear (failure to deploy), the ETA lost control when “weight on wheels”, and flipped over on the runway.

Notably, the main landing gear on the ETA is not the same as what set to be employed on future Dream Chasers.

The beauty of the commercial crew competition is that participants must complete milestones to receive awards from NASA. Failures are not rewarded. Spaceflight Now explains:

NASA and Sierra Nevada have a Space Act Agreement to provide up to $227.5 million of NASA funding to the company. NASA makes payments as Sierra Nevada completes Dream Chaser design and development milestones.

One of the milestones tied to a financial payment was the completion of approach and landing test. Upon meeting predetermined success criteria, Sierra Nevada was set to receive $15 million at the conclusion of the milestone.

The Space Act Agreement describes the test this way: “A minimum of one and up to five additional Engineering Test Article free flight test(s) will be completed to characterize the aerodynamics and controllability of the Dream Chaser Orbital Vehicle outer mold line configuration during the subsonic approach and landing phase.”

The test's success criteria was redacted in a copy of the Space Act Agreement posted online.

Sierra Nevada has not yet disclosed the condition of the ETA. Even if it can be repaired, it will delay further tests and set back the company even further in the competition.

With the final selection of at least one commercial crew participant anticipated for the summer of 2014 (depending on Congressional funding), yesterday's incident would suggest that it's down to SpaceX and Boeing.

But that doesn't put Sierra Nevada out of orbital business. All three companies anticipate flights to the private Bigelow Aerospace inflatable habitats later in the decade.

UPDATE October 27, 2013Alan Boyle of NBC News reports that Sierra Nevada will hold a press conference on Tuesday October 29 to discuss the incident.

UPDATE October 29, 2013 — Sierra Nevada released today a video of the test flight, but not the landing:

Click the arrow to watch the test flight on YouTube. Video source: Sierra Nevada Corporation.

A SNC representative posted this comment on the YouTube video:

We have assembled a team to investigate the cause of the anomaly and cannot release any further video at this time. Thank you for your patience while we conduct the investigation!

Alan Boyle of NBC News reports on today's press conference:

During a teleconference on Tuesday, Sirangelo said the vehicle was “repairable and [would be] flyable again.” There was no damage to the test vehicle's internal shell or electronics, and the damage to the external carbon-composite shell can be fixed, he said. The only question is whether the Dream Chaser would be repaired for another autonomous flight, or retooled for its first piloted flight. Either way, the vehicle would fly again later this year or next year, Sirangelo said.

“Our timeline isn't going to be affected by this,” Sirangelo said. The flight yielded so much good data about Dream Chaser's aerodynamics that “in a strange way [it] might actually accelerate the program,” he said.

Sirangelo stressed that the landing gear used during Saturday's test was adapted from the equipment for an F-5 fighter jet, and would not be used on future configurations of the test vehicle.

Early reports had said the ETA flipped on the runway, but Sirangelo contradicted that.

According to Robert Pearlman at

“Unfortunately, we encountered an anomaly with the gear that we're still investigating, which caused the gear to not deploy properly on the left side,” SNC vice president Mark Sirangelo, head of the company's space systems division, explained to reporters Tuesday (Oct. 29). “After a period of time, the vehicle was unable to continue its roll down the runway and landed down on its left side and skidded off the runway into sandy dirt.”

The prototype space plane, which took several months to build, was damaged from the skid, but was otherwise left intact after the crash.

“The core structure, all of the flight controls, the rudders, the ailerons, all of those are all still attached, still working and are still part of the vehicle,” Sirangelo said. “What we did lose was some of the protective coating shell off of the vehicle and some minor damage to the composites and wheel structure.”

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