Sharp Edge Flight Experiment

Did You Know?

• SHEFEX III is a small space plane-like vehicle expected to launch in the 2020s on a Brazilian VLM rocket.
• The REX-Free Flyer (SHEFEX IV) is planned as a free-flying platform for high quality microgravity experiments over several days.
• The REX-Free Flyer's modular experiment trays closely resemble those found on sounding rockets.

First spacecraft with sharp corners and edges

The SHEFEX concept introduces a spacecraft shape with sharp corners and edges, in contrast to the rounded forms used in existing space flight. Hendrik Weihs, coordinator for returning technologies at DLR, proposed this design. Flat tile shapes can be produced at lower cost than highly individual rounded shapes. Dr. Klaus Hannemann, Head of the spacecraft department at the DLR Institute of Aerodynamics and Flow Technology in Göttingen, noted that a space shuttle has more than 25,000 differently shaped tiles, whereas the simple shape of SHEFEX tiles should lower maintenance costs and allow simple replacement in space. The project also aims to improve aerodynamics. Weihs stated that the capsule almost achieves the aerodynamic characteristics of a space shuttle but is smaller and does not need wings. DLR programmatically explained that curved outer contours with high accuracy requirements were identified as a major cost driver in thermal protection systems. Tessellating the outer contour with flat tiles of only a few distinct shapes reduces costs, and different flat tiles can be produced from a basic tile by cropping. However, sharp edges and corners create very high temperatures that must be controlled by new technologies such as actively cooled elements. Sharp edges also provide aerodynamic advantages, causing lower drag in hypersonic flight conditions.

SHEFEX I

SHEFEX I, the first test vehicle in the SHEFEX series, launched on October 27, 2005, from Norway's Andøya Rocket Range. It climbed to roughly 200 kilometers above the North Sea before plunging back into the atmosphere in just 20 seconds at nearly seven times the speed of sound. Live video and measurement data from the onboard camera streamed directly to the ground station. When the parachute system tried to deploy, a malfunction caused the loss of both the parachute and the flight unit. The German Aerospace Center (DLR) considered the mission a major success because the data analysis yielded crucial findings. The rocket used was a VS-30 Orion, pairing a Brazilian VS-30 first stage with a HAWK second stage. The three-year project cost about 4 million euros and fell under the space program of the Helmholtz Association of German Research Centers (HGF) and DLR.

SHEFEX II

On June 22, 2012, the SHEFEX II vehicle launched from Norway's Andøya Rocket Range atop a Brazilian VS-40 rocket. It climbed to roughly 180 kilometers and hit about 11,000 kilometers per hour, or Mach 11. The craft carried 300 sensors in its tip to track pressure, heat flux, and temperature. Its faceted skin tested nine different thermal protection systems, mostly new fiber ceramics. EADS Astrium, MT Aerospace, and Boeing also ran their own experiments on parts of the surface. During reentry, SHEFEX II withstood temperatures exceeding 2,500 degrees Celsius while beaming data back to the ground station.