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Radames
11-01-2009, 07:58 AM
Dear all,

the problem of today reentry is the heat due to the friction of hypersonic speed (mach ~25).

If there is enough air to heat metals to 1000°C and more, I would expect that this is enough air to produce some lift. Since we need to save weight, I suggest the usage of a paraglider.

My reentry scenario:

The spacecraft has finished its mission in orbit, e.g. height 250 km.
The spacecraft opens a paraglider. In this step it is behind the craft. So it increases the air drag. Because of the thin air it is only a small drag and therefore the temperature is low.
The height of the orbiting spacecraft decreases. The air becomes thicker and the drag starts to heat the craft and the paraglider. To avoid overheating the angle of attack of the paraglider is changed such that it produces less drag and more lift. Due to the lift the craft keeps a higher height but its speed decreases slower.
The speed decreases to subsonic speed. The craft glides to its landing runway and touches down.


Is such a reentry possible?
How long would such a reentry take?

RaresH
11-02-2009, 02:24 AM
Well I like the sound of that. It would certainly take longer if it were feasible. Although it would be cheaper if the heat shielding was bypassed.

Radames
11-08-2009, 03:26 PM
It looks like such designs was studied in the '60, c.f.:

http://www.astronautix.com/craft/paracone.htm
http://www.astronautix.com/craft/reeystem.htm


How can we calculate the heating in low density air at hypersonic speed (mach 25 = 7.5 km/s)?