Sharp Edge Flight Experiment

The Sharp Edge Flight Experiment ( SHEFEX ) ( German sharp-edged flight experiment ) is a program of the German Aerospace Center (DLR ) for the development of some new, cheaper and safer design principles for space capsules and space shuttle with re-entry capability in the atmosphere and their integration into an overall system. DLR explained to the objectives of SHEFEX intentions: The aim of the research is a spaceplane that will from 2020 be traceable for experiments under microgravity conditions available. The spaceplane project is named REX Free Flyer received (REX for Returnable experiment, dt return experiment).

During re-entry from space vehicles in the earth's atmosphere caused by the high velocity of the spacecraft, and the friction of the molecules of air and the displacement of temperatures of about 2000 degrees Celsius. In order not to burn up, spaceships, therefore, so far require very expensive and sometimes failing heat shields.

First spacecraft with sharp corners and edges

The eponymous idea for the sharp-edged flight experiment of Project Hendrik Weihs, coordinator for return technologies in the DLR, is a completely new form for a spacecraft, namely with sharp corners and edges, instead of the round so far used throughout in space forms. Flat individual components that make up this form may be composed, can be produced at lower cost than rounded.

To this basic advantage of the concept explained Dr. Klaus Hannemann, Head of spacecraft at the DLR Institute of Aerodynamics and Flow Technology in Göttingen:

" A space shuttle has more than 25,000 different shaped tiles. Due to the simple form of Shefex tiles, the maintenance costs of the thermal protection system can be reduced and a simple exchange in the universe would be conceivable. "

Further, the managers strive for better aerodynamics. Overall Project Manager Hendrik Weihs said:

" The capsule almost reached the aerodynamic characteristics of a space shuttle, but it is smaller and takes no wings "

Programmatically declared the DLR this:

" From the experience in the development of thermal protection systems, the default curved outer contours with high accuracy could be identified as a major cost factor. Large, curved fiber-ceramic structures require complex manufacturing aids and appropriate for each individual component auxiliary shapes and optimized manufacturing processes. Therefore, a potential savings, the simplification of the outer contour by dissolution in as few flat surfaces dar. Basically, plate-shaped panels can be produced from a basic shape and adapt by simply cutting. This also leads to significant savings in maintenance and replacement of damaged elements. Flow Technically, however, arise during re-entry problems at the edges and corners. There appear to very high temperatures by new technologies, such as actively cooled elements that must be mastered. Aerodynamically, however, arise in the hypersonic flight this shaping also benefits because they generate in this speed range contours with sharp leading edges lower resistance. "

Ceramic fiber composite materials for the heat shield

Suitable materials for the shields fiber-ceramic composite materials. Thus, for example, II tested nine different materials at second rocket test SHEFEX, mostly developments of the DLR in Stuttgart and Cologne. These are - so the DLR - dimensionally stable compared to metallic materials significantly more heat resistant, extremely light and even at high temperatures.

Active cooling of the heat shield

In addition, a thermal protection system is developed and tested, in which, during the re-entry of nitrogen through a porous tile flows and cools the missile. Project Manager Hendrik Weihs told about this Project:

" The escaping gas forms a kind of cooling protective layer around the surface so that the atmospheric gas does not reach the spacecraft "

Control during re-entry at SHEFEX II

The second experiment SHEFEX II was equipped with active aerodynamic control elements that allow an active flight control during re-entry phase. These ceramic called canards with their mechanical actuators and an autonomous control system are another key development goal of the project dar.

Participating Institutes

The flying experiment platform SHEFEX is a collaborative effort of seven DLR institutes and facilities:

• The Institute of Aerodynamics and Flow Technology conducted wind tunnel experiments and calculated the flow field during re-entry and equipping the missile with sensors for measuring temperature, pressure and heat load from.
• The Institute of Structures and Design made ​​the missile, and designed and produced, among others, the ceramic thermal protection systems. At one of these thermal protection systems during re-entry passes through a porous tile nitrogen and so cools the missile.
• The Institute of Flight Systems tested canards, which are control surfaces, with which the position of SHEFEX II to be actively managed.
• The Institute of Materials Research presented ceramic tiles ago
• The Institute for Space Systems and the
• Device simulation and software technology developed a navigation platform for determining the position of the spacecraft during the flight.
• The Mobile Rocket Base MORABA DLR contributed the two- carrier system added, steered the rocket and received the data sent SHEFEX during the flight.

I SHEFEX

The first test vehicle Shefex I started on 28 October 2005 on a two-stage sounding rocket from a launch facility on the island near the Norwegian town of Andenes Andøya. Shefex I reached over the North Sea a height of over 200 km. The unit came within 20 seconds with almost seven times the speed of sound back into the earth's atmosphere. The measurement data as well as live images of the on-board camera were transferred directly to the ground station. Since the activation of the parachute system encountered an error that led to the loss of the parachute system, the flight unit Shefex I was lost. The evaluation of the measured data delivered but according to the DLR important insights that Shefex I could be a great success from the perspective of the DLR. When driving a rocket system was used, which has been combined from a Brazilian VS -30 Sub- stage and a HAWK missile as a secondary school. The cost of the three-year project were approximately 4 million euros and were space in the framework of the program of the Helmholtz Association of German Research Centres ( HGF) and the DLR applied.

SHEFEX II

With the development SHEFEX II should be tested on the faceted outer skin nine different Hitzschutzsysteme. These are mostly developments of fiber ceramic DLR locations in Stuttgart and Cologne. But also the German aerospace company EADS Astrium and MT Aerospace, as well as the international partners were asked Boeing test surfaces available supplement. In the test vehicle sensors were installed, which were developed by the DLR hypersonic technology department in Cologne. You should measure during the flight pressure, heat flux and temperature in the payload tip.

On 22 June 2012 at 21.18 CEST clock the seven -ton, almost 13 meter long rocket was launched with its payload SHEFEX II from the Norwegian rocket launch site Andøya. The space capsule SHEFEX II reached while a height of about 180 kilometers. SHEFEX II flew at a speed of 11,000 kilometers per hour ( eleven times the speed of sound ) through the atmosphere. During re-entry into the atmosphere SHEFEX supernatant II temperatures of over 2,500 degrees centigrade, and sent data from the sensors to the ground station 300.

SHEFEX III

The DLR has for 2016Vorlage: the project SHEFEX III taken future / In 2 years in the eye of the fly much faster, resemble a spaceplane and should stay 15 minutes in the atmosphere. The aim of the research is there, then using this information to develop a missile over days allows experiments in microgravity after its launch and then undamaged in re- scheduled to land on the ground.

REX Free Flyer ( SHEFEX IV)

As a first application for SHEFEX, the German program for hypersonic and re-entry technology development, the REX Free Flyer was envisaged. The system should allow a free-flying platform with high quality micro -G gravity experiments over several days. The possibility of controlled recirculation and a modular design of the experiment racks that much in line with those of sounding rockets should allow experimenters to provide a quick and inexpensive access to their experiments.