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VentureStar - still the future RSV option?

Venture Star - space-plane of the future Venture Star will revolutionise space transportation by delivering payloads to orbit more reliably and less expensively than today's launch vehicles are able to. By dramatically reducing the cost of space travel, Venture Star will finally open the high frontier - enabling a new breed of pioneers to head out into the solar system and explore opportunities on other planets.

The Venture Star is different from the current Space Shuttle in a number of ways. Firstly, it does not drop tanks or rocket boosters along its flight path, so it operates more like a conventional aeroplane. Between flights, Venture Star will simply undergo inspections, refuelling and reloading. There are no components to re-manufacture or reassemble.

By reusing the vehicle, Venture Star will dramatically cut the cost of space travel to as much as one-tenth of what it is today. Unlike the heavy bell nozzles and steering systems on the current space shuttle, the Venture Star will use a new engine, called a "linear aerospike engine". The new engine is lighter, more efficient, and more powerful. Another clever feature of the aerospike engine is that it can automatically adjust to changing atmospheric conditions as the vehicle climbs into orbit, so it maintains very efficient thrust throughout the ascent.

The X33 - baby-brother test vehicle However, before the Venture Star is actually built, Lockheed Martin, the company contracted by NASA to build the space-plane, has to prove it will do everything they claim it can. To do that, they are building a baby brother demo vehicle, called the X-33. The X-33 is half the size of Venture Star, one ninth of the weight and one fourth of the costs to develop - which makes it ideal for prototyping and testing.

The X-33 will also be unmanned - so should anything go wrong, there will be no risk to life. During flight tests, the data collected will enable the developers to predict how the full scale Venture Star will perform.

Once the demonstration flights by the X-33 are completed and evaluated, Lockheed Martin and its civilian partners will decide whether to develop and build Venture Star. They will have to confirm whether the flights by the X-33 have demonstrated that Venture Star is technically possible. Will Venture Star be able to meet the goal of cheap, low-risk, and routine access to space? Above all, will it be profitable?

If the answers are all "yes," then NASA will have to raise the capital needed to carry out the project. It will need to convince potential investors, and its own upper management, that the risk of developing Venture Star is acceptable, because there will be no federal government funding for this project. It will be strictly a commercial undertaking.

If Venture Star is built and proves successful, the cost of launching one pound of payload into low Earth orbit will be reduced from the $10,000 it costs today with the space shuttle, to $1,000. This cost-reduction is likely to dramatically increase space business: Communications satellites; scientific satellites; servicing the International Space Station; exotic manufacturing laboratories exploiting the near zero-gravity conditions of space; and other novel uses of space yet to be invented by twenty-first century entrepreneurs.

One idea could be the sale of leisure excursions to adventurous private citizens. Apparently a Japanese Hotel group is already selling tickets in advance. So who knows, next we could be telling you about an orbiting hotel - watch this space!

The most-developed second generation concept is Lockheed's VentureStar. It was conceived as a single-stage-to-orbit (SSTO) replacement for the shuttle, and R&D; took place throughout the 90's. Though many new technologies were researched, the VentureStar was never built.

The X-33 was to be a half-scale prototype of the VentureStar. As the program went on, the two designs diverged, with the VentureStar picking up an external cargo bay and larger, differently placed fins. Some of this can be discerned in the sequence of pictures at the top of the page.

The X-33 program ran for 56 months; it was cut by NASA in early 2001. Its overall cost was $1.3 billion, shared by NASA and Lockheed. When problems showed up during composite tank testing, Lockheed would have footed the bill (proposed: $100 million in the next two years) for redesign, and had started preliminary work on aluminum tanks.

The X-33 program eventually foundered because it was too innovative. It combined several new ideas and technologies, most of which had never been tried and certainly not tried in combination. The death knell for the project was the failure of a prototype Graphite/Epoxy composite fuel tank during testing. Upon investigation, the tank contained several serious manufacturing flaws. This was not the fault of the design team; it was simply that materials science and composite manufacturing technology was not advanced enough. In several other areas they were also writing the book as they went along. The X-33, a beautiful design, was too far ahead of its time to be built.

The good news is that we now know exactly what to concentrate on so we can integrate it successfully into the next RLV design.

Specifications:
  • X-33 Specs
  • Length: 69 ft
  • Width: 77 ft
  • Takeoff weight: 285,000 lbs
  • Fuel: LH2/O2
  • Fuel weight: 210,000 lbs
  • Main Propulsion: (2) J-2S Linear
  • Take-off Thrust: Aerospikes
  • Maximum Speed: 410,000 lbsMach 13+
Article from http://www.nasaspaceflight.com/ - Jul 26, 2004, 05:45