Stupidly high drag for re-entry? | Command module design | Forum

Post edited 3:23 am – December 1, 2009 by Rocket-To-The-Moon

I was thinking of something like this earlier. We would need a variable system so that we could have very high drag (parachute type device) that is deployed at a very high altitude (120km+). Even though the atmosphere is thin at these altitudes it would help to scrub some of the energy. There could then be a shear pin in the line that would automatically shear when the capsule reaches a certain g force (7-9g for example). Once the shear pin breaks the chute is lost and the capsule returns to a much lower acceleration (1-2g) due entirely to the drag of the capsule itself. The acceleration will continue to build up as the atmosphere becomes more dense at lower altitudes but hopefully it is much less than if there was no high altitude drag chute.

If the parachute had some kind of variable drag coefficient (by opening the hole in the center) we could keep the vehicle at a continuous maximum acceleration until the capsule's drag alone equals the maximum at which point the chute would be cut. This would let us take advantage of the parachute longer instead of cutting (shearing it) it once the acceleration builds to a certain point. The downside is that it is more complex since we would have to modulate the parachute as a function of spacecraft acceleration which doesn't coincide with "the simplest thing that could possibly work".

Is this what you had in mind?

Edit: To clarify, the parachute is providing drag when there is little aerodynamic heating of the capsule.