SNC outline Dream Chaser’s Enterprise-style landing test approach
Sierra Nevada Corporation’s Dream Chaser – one of the leading candidates to win the right to launch US astronauts to the International Space Station (ISS) – is heading towards its extensive Approach and Landing Test (ALT) schedule. Using the Engineering Test Article (ETA) as “their Enterprise”, the testing will ramp up towards crewed landings at Edwards Air Force Base.
Dream Chaser ALT:
Although the start of the Space Shuttle era began when Columbia roared off the launch pad in 1981, the path-finding work that preceded the STS-1 mission was extensive and essential.
The majority of that work was conducted by Enterprise, a vehicle that received approval for its construction nine years before Columbia’s launch, resulting in the test vehicle being transported 36 miles over land from her Palmdale construction facility to Edwards Air Force Base and NASA’s Dryden Flight Research Center in 1977 for the series of ALT tests.
Now, in 2012, the Californian base will welcome another pathfinder vehicle, one that is also aiming to lay the foundations for sending American astronauts into space via NASA’s Commercial Crew program.
“We’re working with the NASA Dryden Flight Test center which is at Edwards Air Force Base,” noted Mark Sirangelo, Corporate Vice President and head of SNC’s Space Systems in an interview with NASASpaceflight.com’s Lee Jay Fingersh, adding that he is fully aware of the heritage behind his “baby shuttle’s” visit to the famous site.
“Edwards is a historical place where many of America’s most famous planes and spacecraft have gotten tested and we like history in that regard. We think there’s a lot of value to it and so we’re going to be doing virtually the same thing that the first Shuttle tests did.”
Like Enterprise, the Dream Chaser ETA will never fly in space. However, it will provide the same level of required flight data for its siblings, as did the famous OV-101, a vehicle now retired to its new home in New York City.
“It is like Enterprise and you could look at it like that way. It’s going to do an Enterprise-like testing called an ‘ALT’ or ‘Approach and Landing Test’,” added Mr Sirangelo.
With the Captive Carry Test already under their belts, along with the successful completion of the Preliminary Design Review (PDR), SNC are now in a position to progress towards the Edwards leg of their test schedule in the the third quarter of this year.
Unlike Enterprise, the tests won’t involve riding atop of the Shuttle Carrier Aircraft (SCA), although they may opt to use another famous carrier aircraft, Scaled Composites White Knight Two (WK2) – although this option is yet to be confirmed, due to the need to confirm its availability during the test phase.
Mr Sirangelo noted that the testing will involve numerous runs and could involve a variety of carrier aircraft, starting with helicopters, later with other aircraft – such as White Knight Two. These initial tests will be uncrewed, to be followed by crewed tests.
As previously noted, the most likely pilot option for the crewed flight tests will be SNC’s own Director of Flight Operations, Steve Lindsey. Mr Sirangelo noted that the former Shuttle commander’s qualifications are obviously extensive.
With the test schedule currently being refined, SNC note they will likely open with test flights via the use of a SkyCrane helicopter, as they did during the Captive Carry Test, before moving on to other carrier aircraft, as they “expand the envelope” to higher and faster tests.
“We want to expand the envelope up, starting low, and gradually increasing in altitude, speed and maneuvers,” added Mr Sirangelo. “It’s going to have some forward momentum (with the helicopter) as we’re moving it and then it’s going to drop very quickly, then it’ll pick up speed and then it’ll pick up lift and then it’ll fly in and do its work.”
The test plan also progresses towards the use of Dream Chaser’s hybrid motors, for the purpose of expanding the flight envelope to be both faster and higher, during the later stages of testing.
While Dream Chaser offers the only major cross range ability out of all the Commercial Crew options – something SNC have previously described as something the ISS program consider particularly valuable, due to its “dissimilar redundancy” when compared to capsules - its landing will offer one unique difference to that of a Space Shuttle orbiter.
With a target a landing speed of 191 knots, Dream Chaser will touch down with its Main Landing Gear, before pitching the nose forward on to an inbuilt skid strip, as opposed to a Nose Landing Gear wheel.
Speaking of the rationale for opting to use a skid strip, SNC noted it is a simple, light, safe option. They also added that there had been some issues with the analysis of the performance of tires in the space environment and this eliminates one of the tires – with the other two tires easier to control than the nose wheel if there’s a problem with one of them.
SNC noted they do not expect any crosswind limitations from the skid.
For Enterprise, the naming of OV-101 was of national interest, with the United States’ bicentennial resulting in NASA choosing the name Constitution for OV-101, prior to a letter writing campaign by Star Trek fans, leading NASA to opt for the name of the TV show’s flagship.
As for the Dream Chaser fleet, SNC noted they have talked about giving names to the vehicles, but no decision has yet been made thus far.
The next Dream Chaser article will focus on the vehicle’s launch and on orbit operations.
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