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> The Superdracos are powerful engines but they don't have anything near the delta-v to always return to land after an abort even if you fill the entire Dragon
by speedplane 7y ago
> The Superdracos are powerful engines but they don't have anything near the delta-v to always return to land after an abort even if you fill the entire Dragon with propellant. So you'd always need the chutes anyway.
Not sure that's true. The chutes bring the speed of the capsule down quite a bit, just a short burst of the dracos at the last few feet could allow it to softly land and wouldn't require much propellant. This is exactly what the Soyuz does. My guess is that this approach was rejected by NASA (not SpaceX) due to complexity rather than feasibility.
- hadlock 7y agoThis is what's referred to in some circles as a "suicide burn"; in that you wait until the absolute last second, then ignite the engines at full throttle to zero out velocity. Assuming the engines work, it's very efficent as you're not accruing what's called "gravity drag" as the velocity goes to zero very rapidly and you're not fighting 9.8m/s acceleration. If the engines don't start, or you don't get the predicted thrust out of them, well, that's why it's called a suicide burn.
- speedplane 7y ago> If the engines don't start, or you don't get the predicted thrust out of them, well, that's why it's called a suicide burn. Fair enough, but this is exactly what the Soyuz has done for decades, and NASA (as well as Roscosmos) found the approach to be acceptable for human spaceflight. It may introduce complications, but it's clear that it's doable.