Re:Soyuz capsule landing and retrieval photos
by pvg on Wednesday October 06, 2010 @02:51AM
(#1763003)
I meant that as in contrast with the apollo craft which had 3 parachutes
Yeah that's an interesting question. I don't have a definitive answer but we can make some semi-educated guesses by googling about.
I think the failure mode designers worried about was not the parachute just up and ripping off - the forces involved and component strengths and safeties required could be computed. They were concerned about parachutes failing to deploy at all or failing to deploy effectively, which is harder to model and predict.
Both Soviet and early US landing capsules (Mercury, Gemini) had single parachute systems. The Soviet safety design choice from the beginning was a fully redundant main parachute system. I don't know what the setup was for Mercury, Gemini capsules had ejection seats in case the main parachute failed.
Apollo Command Modules, designed to go to the Moon, were both heavier than the other capsules of the time and had stricter weight constraints. It seems like NASA determined two parachutes failing was extremely unlikely. So three parachutes, one of which can fail seems like the right choice given the constraints of weight and safety.
The actual recorded failures appear to confirm the difficulties were about deployment, more than anything else.
In 1967, Soyuz 1's main parachute failed to deploy, the backup parachute deployed but got tangled in the drogue and was ineffective. Cosmonaut Vladimir Komarov was killed on impact.
In 1971, Apollo 15 splashed down safely with two functional and one failed main parachute.
Yeah that's an interesting question. I don't have a definitive answer but we can make some semi-educated guesses by googling about.
I think the failure mode designers worried about was not the parachute just up and ripping off - the forces involved and component strengths and safeties required could be computed. They were concerned about parachutes failing to deploy at all or failing to deploy effectively, which is harder to model and predict.
Both Soviet and early US landing capsules (Mercury, Gemini) had single parachute systems. The Soviet safety design choice from the beginning was a fully redundant main parachute system. I don't know what the setup was for Mercury, Gemini capsules had ejection seats in case the main parachute failed.
Apollo Command Modules, designed to go to the Moon, were both heavier than the other capsules of the time and had stricter weight constraints. It seems like NASA determined two parachutes failing was extremely unlikely. So three parachutes, one of which can fail seems like the right choice given the constraints of weight and safety.
The actual recorded failures appear to confirm the difficulties were about deployment, more than anything else.
In 1967, Soyuz 1's main parachute failed to deploy, the backup parachute deployed but got tangled in the drogue and was ineffective. Cosmonaut Vladimir Komarov was killed on impact.
In 1971, Apollo 15 splashed down safely with two functional and one failed main parachute.
http://en.wikipedia.org/wiki/Soyuz_1 http://en.wikipedia.org/wiki/Apollo_15
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/1973006... http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/1966002...