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TOPIC: German TPS: Sharp Edge Flight Experiment (Shefex)

10kBq Jaro

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Date: Nov 14, 2005

German TPS: Sharp Edge Flight Experiment (Shefex)	Permalink

Space Technology Germany Flight Tests Low-Cost Thermal Protection Technology for Spacecraft Aviation Week & Space Technology, 11/14/2005, page 54 Robert Wall, Paris Low-cost thermal protection system targets ESA's future launcher programs German researchers will crunch data in the next few weeks to determine for certain whether their newly flight-tested thermal protection system for future spacecraft met durability goals, after initial indications that the technology passed its first major operational trial. Officials with the German aerospace center (DLR) say they have generated plenty of data to evaluate the performance of the Sharp Edge Flight Experiment (Shefex), although the Oct. 27 flight incurred a problem during the descent phase that led the parachute recovery system to deploy too early and then tear off because of high speed, causing the vehicle to be lost at sea. The flight took place at the Andoya Rocket Range in Norway. The primary goal of the trial was to assess the thermal protection technology the Germans developed and were hoping to fly on NASA's X-38, the crew return vehicle prototype, before that project was terminated. German researchers believe the technology can be produced at about half the cost of NASA's space shuttle thermal tiles, and also have far lower maintenance costs, says project manager Norbert Puttmann. The main reason for the lower cost is that designers have opted for flat, rather than curved, tiles. The flat approach allows them to manufacture a large sheet from which identical protection panels can be cut, a much easier production process than is now used. The panels are attached to the reentry body via ceramic screws and bolts, reducing the tough labor associated with current technology, DLR argues. The Shefex flight was launched Oct. 27 on a sounding rocket consisting of a VS-30 first stage and Hawk missile second stage (left), to explore new thermal protection technology that would allow design of edged tiles (below). Credit: DLR PHOTOS http://www.aviationnow.com/media/images/awst_images/large/AW_11_14_2005_1901_L.jpg Credit: DLR PHOTOS The tiles are also designed to withstand higher temperatures than those on the shuttle. In fact, the flight-tested 3-mm.-thick, carbon-fiber-reinforced silicon carbide is designed to withstand 1800C and be reused thereafter, although developers believe that's not the upper limit. Temperatures during the recent flight test were expected to top out at shuttle-like 1600C. Resistance to higher temperatures allows for an edged design, rather than a rounded one; the former is easier to produce, but can encounter higher temperatures during reentry, Puttmann says. In the flight test, the Shefex was launched using a hybrid sounding rocket consisting of a Brazilian VS-30 as a lower stage, with a Hawk missile serving as the upper stage. The rocket carried Shefex to 211.5 km. (131.5 mi.) altitude. Shefex and the burnt-out Hawk--still attached to make use of its control surfaces--then reentered the atmosphere and reached almost Mach 7. The inadvertent early parachute deployment occurred at about 12 km. altitude. Despite the problems during descent, engineers were able to collect even more mission data than expected, Puttmann says. Readings included input from 61 of 64 pressure sensors--three failed--suggesting that the ceramic protection system withstood the high temperatures. Project officials expect to process a large amount of data in the coming weeks so they can present the first concrete findings during a program review in December. At that point, officials will also discuss whether to conduct a second flight experiment targeting even higher temperatures. Results will also be briefed to European Space Agency representatives, who are interested in incorporating the technology in their Future Launcher Preparatory Program. NASA has been keeping an eye on the endeavor, too, as the new material could allow much higher reentry speeds and temperatures, which would be likely on a return from the Moon or Mars. The flight also represented DLR's first hypersonic mission. DLR has spent about 4 million euros ($4.72 million) on Shefex. __________________

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