Posts Tagged‘drop test’

Dream Chaser: The Other Shuttle Replacement.

The International Space Station hasn’t really been struggling since the retirement of the Shuttle with it still being able to maintain its full 6 person crew even with the significantly reduced launch capacity. Indeed the bevy of alternative craft that have been visiting the ISS, such as the SpaceX Dragon and the Orbital Sciences Cygnus, have meant that it’s also been well supplied in the absence of a largo cargo tug like the Shuttle. Still there is no current replacement for getting humans up there with that responsibility falling solely to the Russian Soyuz craft although NASA is funding some alternatives. I’ve covered most of them in the past but one of the main contenders, Sierra Nevada Corporation’s Dream Chaser, just passed a significant milestone, albeit with a few issues.

Dream_Chaser_pre-drop_tests.6Their craft bears a striking resemblance to the Shuttle, sporting the same thermal tile underside and similar aerodynamic profile. It’s quite a bit smaller than the Shuttle however, being about a quarter of the length and a seventh of the mass, mostly due to its lack of payload bay. It can still carry up a comparable number of astronauts however, up to 7 in its current configuration which is only 1 shy of the Shuttle’s maximum. The design is also quite interesting as whilst it looks like any other space plane it is in fact a lifting body with those wings being on there for control purposes only.

Lifting bodies are an interesting type of craft whereby the craft’s design makes it one giant aerofoil, eliminating the need for big wings in order to generate lift. Indeed NASA has quite a history with lifting body craft having designed and built at least 3 of them in the past. The idea was solid enough for it even to be considered as one of the alternative designs for the Space Shuttle itself although the other requirements (primarily from the Department of Defense) meant that it wasn’t used in the end. Dream Chaser’s design then uses the lifting body for simplicity and efficiency, allowing for their smaller craft to do the one task of ferrying humans into orbit well without any of the additional cruft that plagued the Shuttle.

Dream Chaser recently underwent its first unmanned drop test to confirm its flight characteristics and to give all of its systems their first shakedown. For the most part the mission was a success with the lifting body performing as expected and the remote control systems functioning perfectly. However upon landing the left landing gear failed to deploy causing the craft to spin uncontrollably when the left wing contacted the run way. It’s eerily similar to the landing skid failure that SpaceShipOne encountered during one of its shakedown flights, although that one had a person inside it at the time (he was unscathed, however). It’s not a show stopping issue but it will probably mean furthering testing will be delayed until they can figure out why it happened, and make repairs to their prototype.

For what its worth I think the future of space travel will be in craft like Dream Chaser, ones that favour simplicity and efficiency over trying to make a multi-purpose craft. Indeed all the current contenders in the private space industry are doing just that, building craft with a specific purpose in mind and ensuring they do it efficiently. Whilst this first drop test might have had some hiccups it’s shown that the lifting body idea is aerodynamically sound and that there’s no fundamental flaws in their idea. Once they’ve worked out that landing gear kink I’m sure we’ll see dozens of successful drop tests to follow and, hopefully, some fully powered tests in the not too distant future.