Problems of Ensuring Sub-orbital Cruise Safety

Paper number

IAC-08.D5.1.1

Author

Prof. Alexander Filatyev, Central Aero-HydroDynamic Institute, Russia

Coauthor

Mr. Alexander Golikov, Central Aero-HydroDynamic Institute, Russia

Coauthor

Dr. Olga Yanova, Central Aero-HydroDynamic Institute, Russia

Year

2008

Abstract

One of the major factors determining the safety of sub-orbital transportation systems (SOTS) for space tourism is to ensure a permissible g-load level at ascent and descent phases. According to the theory of non-equilibrium atmospheric reentry (Filatyev, A.S. Space Vehicle Safety Problem: Reentry with Subcircular Speeds. Science and Technology Series “Space Safety and Rescue”, v. 87, 1993) the aerodynamic loads can considerably increase due to reduction of the initial velocity (at apogee) of a reentry vehicle (RV). Therefore the implementation of sub-orbital flights, however paradoxical it may be, can face with additional problems of the maintenance of a permissible load level as compared to reentry of the same vehicle from the Earth orbit.

    Two rated cases of critical importance for SOTS safety are considered in this paper:

    1. Ensuring acceptable loads at all phases of a nominal flight due to setting appropriate values of RV and launcher parameters.

    2. Ensuring acceptable RV’s loads after the ascent abort. In these circumstances the velocity of atmospheric reentry is less than nominal one that can result, as mentioned above, in significant raise of aerodynamic loads.

    In the first case it is shown that requirements to SOTS at the ascent and descent phases become contradictory, that bounds such parameters as mass and apogee speed of RV both above and below. As a result the required level of g-loads on ascent and descent phases at the assigned launcher characteristics determines a quite narrow range of admissible RV design parameters.

    In the second case it is obtained that if RV parameters don’t enable to return from any trajectory point without an excess of permissible g-loads, the nominal injection trajectory should be shaped in view of fail-safety requirements. The synthesis of fail-safe control laws and SOTS injection trajectories is shown in the paper.

    The peculiarities of SOTS safety requirements are demonstrated with examples of some perspective launchers and reentry vehicles. 

Abstract document

IAC-08.D5.1.1.pdf

Manuscript document

IAC-08.D5.1.1.pdf (🔒 authorized access only).

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