The first glitch in a successful program to qualify the Sierra Nevada Dream Chaser as a Space Station crew taxi vehicle happened March 26.
The Dream Chaser engineering test article was released from an Erickson Sky Crane helicopter at 12,500 feet.
The unmanned prototype followed its automated flight programs perfectly, first diving at 50 degrees, then going to gentle glide slope. It tracked to the landing strip centerline perfectly. But when the landing carriage was commanded down, the left landing gear was slow coming down. Despite the software attempting to hold the left wing up, it scraped the ground. Then in a cloud of dust Dream Chaser veered off the runway and ended in a vertical position.
While the on-board software did its best to hold up the left wing as long as possible after the Dream Chaser prototype’s successful touch down on the centre line of the runway, the unsupported wing did eventually drop to the ground. The result was that the Dream Chaser prototype skidded off the runway in a cloud of dust and sand, ending up after this in an upright position. It is likely that there was a mechanical failure.
The glide flight lasted approximately one minute. The 50 degrees down angle was held for about 10 seconds, both to gain speed and to match the approach that the full space-capable version of the Dream Chaser would perform. At 200 feet altitude, the on-board ground radar altimeter released the F-5 jet-fighter sourced undercarriage. The final approach lasted approximately 20 seconds at a speed of roughly 160-162 kt.
The testing is being conducted jointly by NASA’s Dryden Flight Research Center and Sierra Nevada under a Space Act Agreement. Testing is at Edwards AFB.
There were no injuries associated with the accident, and it was reported that there had been no significant damage to the crew compartment, and that any crew would have survived such an event. Before the free flight test, there have been a series of ground tow testing, and captive carry tests of aerodynamic characteristics without incidents.
Sierra Nevada says that Dream Chaser remains on target to make its first unmanned spaceflight in 2016 on top of an Atlas V launch vehicle, with the first piloted orbital spaceflight following in mid-to-late 2017.