Space Rotor - A French Concept for a Reusable Recovery System 670391
The space rotor corresponds to a device designed to satisfy the general requirement for a light, maneuvrable, fully reusable reentry system, having a high capability to spot-land, softly, a variety of space vehicles in unprepared areas.
Recent feasibility studies carried out for the “Centre de Prospective et d'Evaluation” under French Ministry of Defence contracts have shawn that the space rotor exhibits a number remarkable features, its light weight characteristics, when compared with maneuvrable or ballistic reentry means, being the most striking ones. In general the combined system, space-rotor-vehicle, can be regarded as a hypersonic glider having a L/D ratio of the order of 1.0 to 1.5. However, whatever are the applications envisaged, booster recoveries, orbital recoveries of manned or unmanned vehicles, the weight penalty incurred by this new system is fairly constant and situated well below that of the equivalent, more conventional, means of reentry and recovery. The feasibility studies show that the rotating parts of a space rotor amount to 7 % to 9 % and the total recovery system to 11 % to 14 % of the total landed weight. In consequence equivalent missions can be satisfied using half as powerful launchers, or inversely the same launchers can put, for the same mission, twice as much useful load into the orbit.
From a practical point of view the space rotor represesnts a fully reusable metallic structure built from nickel superalloys to withstand temperature ranging from 1650°F to 1800°F. During the reentry the heat problems of the space rotor are considerably reduced thanks to the migrating stagnation point effect which eliminates the usual “hot spots” present on fixed geometry vehicles and levels down the temperature distribution to the mean radiation temperature. The variable geometry of the space rotor confers to this system the capability to reconcile, in one integral system, the difficult problems of the maneuvrable hypersonic reentry and the soft spot landing. In fact the final flare permits to use the stored kinetic energy of the rotor to reduce the approach velocity of the vehicle from 40 kts to 6 ft/sec.
The paper ends with an analysis of the technological and economical advantages of the space rotor and their comparison with other reentry and recovery means. A project of an aerospace transporter is presented as an other example of the potential capabilities of the rotary wing techniques for low cost orbital transportation.