A Breath of Fresh Air for Re-entry Technology

Olá leitor!

Segue abaixo uma matéria em inglês publicada na edição de dezembro de 2010 da revista “DLR MAGAZINE”, destacando o projeto alemão SHEFEX II (Sharp Edge Flight Experiment II) que contará com a participação do Instituto de Aeronáutica e Espaço (IAE) cedendo um foguete brasileiro VS-40 para o lançamento deste experimento no espaço, previsto agora para ocorrer da Base de Woomera (sul da Austrália) no segundo semestre de 2011, segundo consta na programação do site da agência espacial alemã.

Duda Falcão

A Breath of Fresh Air for

Re-entry Technology

A new German project with the potential to unlock novel possibilities

for spaceflight, DLR has developed the experimental SHEFEX II spacecraft

that promises to make flying to space and back safer, cheaper and more

flexible. This aerospace project utilises innovative Technologies including a

sharp-edged heat shield with actively cooled elements.

Angular-Design Spacecraft SHEFEX II Set for Space

By Jens Wucherpfennig

The heart of SHEFEX II - the angular nose cone after assembly

in Stuttgart; (from left to right) Hannah Böhrk, Henning ElsäBer

and project manager Hendrik Weihs stand beside their experimental

re-entry vehicle. They are looking forward eagerly to the launch

of the new spacecraft in early 2011

SHEFEX II, which stands for Sharp edge flight experiment, is expected to take off from Woomera in Austrália at the beginning of 2011. It is a unique spacecraft in more ways than one. Even at first glance, the differences when compared to previous spacecraft are immediately apparent. Compared to re-entry vehicles of today, its outer skin is angular rather than rounded, and for the first time in spaceflight, SHEFEX II Will test an actively-cooled heat shield. In addition, it is the first actively-controlled spacecraft with re-entry capability that hás been built and financed by Germany alone.

The two-metre long spacecraft has undergone comprehensive testing during its three-year development programme. During autumm 2010, it will be mounted on a two-stage sounding rocket at DLR Oberpfaffenhofen. The rocket will be launched from the Woomera test site in Australia in early 2011. This second flight in the DLR SHEFEX programme will test the spacecraft’s angular design, its novel thermal protection and innovative control system.

Like a flying wind tunnel

Numerous sensors will measure the aerodynamic effects and behaviour of the spacecraft during re-entry into the atmosphere – one of the most critical moments in spaceflight. Like a flying Wind tunnel, SHEFEX II is expected to deliver additional data to aid further development. At the core of this cutting-edge technology are 160 sensors that have been integrated by DLR’s Supersonic and Hypersonic Technology Department in Cologne. These are intended to monitor the pressure, heat flow, and temperature at the tipo of the payload during the flight. Their findings concerning the processes affecting the craft’s external skin, at temperatures that are expected to exceed 2000 degrees Celsius, will be the most valuable results of the flight experiment.

SHEFEX II will test nine different thermal protection systems making up its multi-faceted outer skin, which are largely the result of the development of fibre-reinforced ceramics by DLR in Stuttgard and Cologne, and well as experiments by German aerospace industry (Astrium na MIT Aerospace) and international partners.

Germany at the cutting edge

“Germany is playing a pioneering role in advanced re-entry systems,” explains Hendrik Weihs, a researcher at DLR’s Institute of Structures and Design in Stuttgard and Project Manager of the national SHEFEX programme. His view of the future sees a possibly manned European spaceflight programme. The idea behind SHEFEX is to use its experimental flights to explore new re-entry technologies as economically as possible. To pursue this goal, the test vehicle will be launched on a relatively low-cost sounding rocket.

Its predecessor, SHEFEX I, was launched from the north of Norway in 2005 on a combination of a Brazilian VS-30 lower-stage rocket and a Hawk upper stage. Following its launch, SHEFEX I reached an altitude of 211.5 kilometres over the Norwegian Sea and re-entered Earth’s atmosphere at almost seven times the speed of sound – fast enough to generate temperatures of 1600 degrees Celsius at the sharp leading edge of the payload. These temperatures are typical for a spacecraft as it re-enters Earth’s Atmosphere. During re-entry, the experimental body remained coupled to the upper stage in order to utilize its fins for stabilisation.

Valuable findings despite the loss of SHEFEX I

SHEFEX I should have splashed down after a nine-minute flight, some 200 kilometres from the launch site. However , the real-time vídeo transmission from the rocket revealed that the recovery system – a parachute and buoyancy device – had been deployed too early, at too high a velocity. SHEFEX I was lost at sea, but the mission was still a success because of the valuable data that it sent back; besides, recovery was only na add-on option and not a primary mission goal. Analysis of the test results confirmed that the high cost of the complex, shaped components used in the test device’s construction could be reduced drastically by replacing them with flat panels. This simplified configuration could potentially lead to significant cost savings during maintenance and replacement of damaged components on future reusable vehicles along Space Shuttle lines. With a relatively modest budget – approximately four million Euro, the larger part of which was spent on the experiment and not its Carrier – excellent results were achieved.

At 12.6 metres in height, the rocket that will carry SHEFEX II is a larger Brazilian model, selected to achieve a higher velocity – up to 12,000 kilometres per hour. In contrast with its predecessor, SHEFEX II boasts small moveable wings, called canards, for flight control. The launch from Woomera should take SHEFEX II to an altitude of 200 kilometres. The descent and re-entry into Earth’s atmosphere – at altitudes of 100 to 200 kilometres – interests the researchers the most. The vehicles’s subsequent landing in the desert with the aid of a parachute will ensure that the spacecraft can be recovered.

Also in contrast to its predecessor, SHEFEX II will be actively steered upon re-entry. DLR has developed a custom aerodynamic flight control system that will guide the spacecraft as it returns to Earth. The key components of the ‘Canard Control System’, designed by DLR researchers at its Institute of Flight Systems in Braunschweig, are the canard control surfaces mounted near the front of the craft, which provide active guidance. Initial ground tests have been conducted successfully.

Landing in Germany also a possibility

The objective of the SHEFEX programme is the creation of a novel orbital glider called ‘REX Free-Flyer’, to be available for conducting experiments under zero gravity conditions from 2020. This vehicle might have come from a science-fiction film, and is perhaps the harbinger of future space travel. Its angular shape promises two significant advantages. Firstly, its heat shield can be simpler and safer, and secondly, its faceted shape provides improved aerodynamic properties. “Application of SHEFEX technology will enable a relatively simple design and therefore a low cost orbital glider, with precision landing capabilities like the Space Shuttle,” says DLR Project head Weihs. “From the technical point of view, REX will be able to land at any normal airport or airfield in Germany.” This technology opens the door to numerous future applications. Re-entry technology lies at the heart of many space missons, ranging from sample-return journeys – for example, the collection of samples from the Moon or Mars – to manned re-entry vehicles, forming parto f a fully or partially reusable space transportation system. This new technology could also be of interest for space tourism.

Expertise from various DLR institutes

The aerodynamic design is a result of computer simulations of flow characteristics and tests in various wind tunnels performed at DLR’s Institute of Aerodynamics and Flow Technology in Braunschweig, Cologne and Göttingen. Researchers in Cologne are in charge of payload instrumentation. The SHEFEX II experiment itself has been developed, manufactured and integrated by the DLR Institute of Structures and Design in Stuttgart, while personnel from DLR’s Institute of Flight Systems in Braunschweig are responsible for theflight guidance system. DLR’s Mobile Rocket Base, Moraba, in Oberpfaffenhofen is responsible for the rocket and launch, while the newly established DLR Institute of Space Systems in Bremen is providing a navigation experiment.

About the author:

Jens Wucherpfennig is a Communication

Officer at DLR’s Göttingen facility

More Information:

www.DLR.de/en/shefex

Source: DLR Magazine - December 2010 - pages 24 to 27

Comentário: Apesar da matéria da revista alemã confirmar o vôo do SHEFEX II para os primeiros meses desse ano, como já havíamos divulgado o vôo só ocorrerá entre os meses de setembro e outubro desse ano, portanto somente no segundo semestre. Vale sempre lembrar leitor que a Missão VS-40/SHEFEX II carregará abordo um experimento brasileiro relativo ao projeto da SARA Orbital.