FLEX - Flexibles and Expansion Joints

Short Description

Liquid rocket engines usually have the possibility of gimballing. Several lines are needed to supply the engine. Typical lines are feed lines, pressurisation lines, purge lines. Flexibility of these lines is necessary, so that they can accommodate deflections imposed by the engine (additional to vibrations, temperature, pressure...) and cryogenic fluid media (LH 2 ... liquid hydrogen, LO X ... liquid oxygen and others).

Therefore engine lines are the most complex lines and have limited life time due to big deflections. The lines may have diameters between 6 and 200 mm. Future propulsion systems will operate at higher pressures compared to actual ones (currently 5 to 10 bar). Therefore flexible lines need to become more sophisticated requiring advanced development techniques.

During the work following aspects have been worked out:

  • requirements for flexible elements from general stage routing considerations have been derived
  • different designs of expansion joints and flexibles (advantages and disadvantages) have been analysed
  • knowledge about the behaviour of expansion joints and flexible hoses and their life time has been increased
  • The methods to predict the life time of expansion joints and flexible hoses have been analysed and new methods for life time and behaviour prediction of flexible hoses have been shown

This study was not only limited to cryogenic feed lines for launchers, but evidently focussed on cryogenic fluids as for future launchers (NGL). Furthermore, this study also includes data of American and Asian stages.

Project Partners


Magna Steyr Fahrzeugtechnik AG & Co KG, Division Space Technology - DI Kurt Irnberger

Contact Address