19. July 2021
Ready for practical use

Hy­brid rock­et en­gine VIS­E­RI­ON suc­cess­ful­ly test­ed

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Space
VISERION hybrid rocket engine test in Trauen
VIS­E­RI­ON hy­brid rock­et en­gine test in Trauen
Image 1/4, Credit: DLR (CC BY-NC-ND 3.0)

VISERION hybrid rocket engine test in Trauen

VIS­E­RI­ON hy­brid rock­et en­gine test in Trauen.
Video: VIS­E­RI­ON hy­brid rock­et en­gine on the test bench
Video 2/4, Credit: © DLR. All rights reserved

Video: VISERION hybrid rocket engine on the test bench

Length: 00:00:56
Dur­ing the test runs at the fa­cil­i­ty at DLR's Trauen site, the cat­alyt­i­cal­ly de­com­posed hy­dro­gen per­ox­ide en­tered the com­bus­tion cham­ber at ap­prox­i­mate­ly 650 de­grees Cel­sius. The heat re­leased was con­vert­ed in­to ki­net­ic en­er­gy – pro­vid­ing ap­prox­i­mate­ly 12,000 new­tons of thrust.
VISERION engine
VIS­E­RI­ON en­gine
Image 3/4, Credit: DLR (CC BY-NC-ND 3.0)

VISERION engine

The VIS­E­RI­ON en­gine on the 'Viererblock' test stand at the In­sti­tute of Aero­dy­nam­ics and Flow Tech­nol­o­gy at DLR Trauen. VIS­E­RI­ON is a lab­o­ra­to­ry en­gine whose in­ner work­ings can al­so be used in a lightweight ver­sion suit­able for flight vir­tu­al­ly un­al­tered.
Schematic of a hybrid rocket engine
Schemat­ic of a hy­brid rock­et en­gine
Image 4/4, Credit: DLR (CC BY-NC-ND 3.0)

Schematic of a hybrid rocket engine

Hy­brid rock­et en­gines are com­bi­na­tions of sol­id and liq­uid en­gines and com­bine the best fea­tures of both en­gine types. The liq­uid oxy­gen car­ri­er re­quired for com­bus­tion – in this case high­ly con­cen­trat­ed hy­dro­gen per­ox­ide – and the sol­id fu­el hy­drox­yl-ter­mi­nat­ed polybu­ta­di­ene (HTPB) are present in VIS­E­RI­ON in dif­fer­ent phys­i­cal states and on­ly re­act with each oth­er at high tem­per­a­tures and pres­sures in the com­bus­tion cham­ber. The ad­van­tage is that, as a re­sult, there is no risk of ex­plo­sion dur­ing stor­age and op­er­a­tion. Fur­ther­more, the sub­stances used are non-tox­ic and not haz­ardous to the en­vi­ron­ment.
  • Hybrid rocket engines can be operated more economically and safely than conventional rocket engines.
  • The tests show that the new VISERION engine is more efficient than its predecessors.
  • To ensure environment-friendly and safe operation, hydrogen peroxide is used for combustion.
  • In addition to a more compact design, components made of carbon fibre reinforced polymers are used.
  • Focus: Space, safety and security

Following the successful test of the novel hybrid rocket engine 'AHRES-B' in spring 2019, the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) carried out two further successful tests with the significantly larger VISERION variant on 17 June and 7 July 2021. The test preparations and commissioning were carried out by a team from the Spacecraft Department of the Institute of Aerodynamics and Flow Technology at the test stand for hybrid rocket engines at the DLR site in Trauen.

The results of the current tests show that the VISERION engine, which was developed in the DLR projects AHRES and ATEK and is now being tested in the DLR cross-sectional Simulation Based Certification (SimBaCon) project, is far more efficient than previous hybrid rocket engines. For the researchers at the Institute of Aerodynamics and Flow Technology, this is a particular cause for celebration, because hybrid rocket engines are not only fundamentally more economical and safer than conventional rocket engines, VISERION is also significantly more efficient than all of its predecessors. "The current tests have shown that the technological development of hybrid rocket engines has now advanced far enough for practical uses such as in sounding rockets," explains Thino Eggers, Head of the Spacecraft Department at the DLR Institute of Aerodynamics and Flow Technology.

What are hybrid rocket engines?

Hybrid rocket engines are combinations of solid and liquid engines and combine the best features of both engine types. The liquid oxygen carrier required for combustion – in this case highly concentrated hydrogen peroxide – and the solid fuel hydroxyl-terminated polybutadiene (HTPB) are present in VISERION in different physical states and only react with each other at high temperatures and pressures in the combustion chamber. The advantage is that, as a result, there is no risk of explosion during storage and operation. Furthermore, the substances used are non-toxic and not environmentally unfriendly.

More compact, lighter and safer

In contrast to other oxidiser-fuel combinations used in hybrid engines, the use of hydrogen peroxide as an oxidiser has some significant advantages. For example, its use allows for noticeably more compact engines than those that use liquid oxygen. The flat curve of the specific impulse allows for improved controllability, and simple ignition by catalysis eliminates the need for an igniter as an additional component. The significantly lower combustion chamber temperature and the resulting lower structural requirements also result in a weight saving regarding the thermal protection systems. Furthermore, the hydrogen peroxide used here is easier to handle and store than, for example, the liquid oxygen normally used.

During the test runs at the experimental facility at DLR's Trauen site, the catalytically decomposed hydrogen peroxide entered the combustion chamber at approximately 650 degrees Celsius. The heat released was converted into kinetic energy – providing approximately 12,000 newtons of thrust. In the process, VISERION consumed almost the entirety of the fuel over a period of 27 seconds and, similar to AHRES-B, achieved a significantly increased burn rate compared to earlier hybrid rocket engines. The latter fact is important for the design of an efficient and compact engine and was also achieved in VISERION using an innovative, twisted 'fin geometry'.

Pioneer for efficient and flexible sounding rockets

The test stand in Trauen is equipped with numerous modern measuring and control facilities and enables the safe test operation of hybrid rocket engines. The infrastructure for the safe, environment-friendly handling of large quantities of hydrogen peroxide is the only one of its kind in Germany.

"The functional verification is an essential milestone on the way to a flight-capable combustor in lightweight construction with a supporting structure made of carbon fibre reinforced polymers (CFRP)," adds Eggers. "The flight-capable variant is being further developed under the name VISERION+ and can serve as a hybrid upper stage for future high-altitude research experiments."

Research on hybrid rocket engines at DLR

The development and supervision of the production of the VISERION engine were carried out at the DLR Institute of Aerodynamics and Flow Technology in Braunschweig. The funds for the construction of VISERION were provided by the the Investitions- und Förderbank des Landes Niedersachsen (NBank). In terms of personnel, the activities relating to VISERION have also been supported since January 2021 by the newly founded Competence Centre for Responsive Space of DLR's Security Research, which has a particular interest in alternative, simply constructed upper stages for satellite transport.

Contact
  • Andreas Ellmerer
    Ed­i­tor
    Ger­man Aerospace Cen­ter (DLR)
    Me­dia Re­la­tions
    Com­mu­ni­ca­tions and Me­dia Re­la­tions
    Telephone: +49 2203 601-3983
    Linder Höhe
    51147 Cologne
    Contact
  • Stefan May
    Test man­age­ment VIS­E­RI­ON
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of Aero­dy­nam­ics and Flow Tech­nol­o­gy
    Space­craft
    Lilienthalplatz 7
    38108 Braunschweig
    Contact
  • Vera Koopmann
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of Aero­dy­nam­ics and Flow Tech­nol­o­gy
    Telephone: +49 531 295-3405
    Lilienthalplatz 7
    38108 Braunschweig
    Contact
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