5 ms·

After Blue Origin’s rocket explodes, its spacecraft makes a dramatic escape

8 points by _Microft 4y ago

aaroninsf 4y ago
Mentioned this in another thread on the fail, the live feed claims the capsule landing was softened by retrothrusters firing before impact. Stepping through the YouTube video frame by frame I see no sign of that... ...did they walk this back yet? Or is just poor video? (I don't think so but it's possible...)
- egberts1 4y ago
  And boy … what a fiery dust cloud that was stirred up by its seemingly harsh landing.
- _Microft 4y ago
  From what I know the retrothrusters ignite in the very last moment. The cloud of dust could well be from that, not only from the impact. Soyuz capsules also soften the landing like that. From what I remember Soyuz ignites its retro rockets less than 1m above ground [0]. [0] https://youtu.be/CYqW0rDEjnE?t=140 https://youtu.be/CYqW0rDEjnE?t=140
  - aaroninsf 4y ago
    I cannot imagine thrust initiated in the last tens of milliseconds being able to ramp up and operate sufficiently to cause meaningful deceleration, and also cannot see how this could do more than "round off" the deceleration curve (lower the spike of force/stress). I take your word for it, I just... can't imagine. That's a failure I guess of imagination and reasoning by analogy instead of looking at the math. It sounds like trading being punched with impact for being punched by 10ms of thrust then a slightly softer punch of impact!
    - _Microft 4y ago
      Apologies for the late reply. If the retro rockets make the deceleration take twice or three times as long, then the acceleration is only half or a third of the impact without braking. That's most likely quite an improvement. I do not know any details about the retro rockets of Blue Origin's capsule or Soyuz but here is some information about the system that SpaceX uses for their launch escape system. The Crew Dragon capsule has eight SuperDraco [0] engines meant to push it away from a failing rocket. These engines have 71kN thrust (16000 lbf) each and reach full thrust a mere 100ms after ignition. [0] https://en.wikipedia.org/wiki/SuperDraco https://en.wikipedia.org/wiki/SuperDraco
themadturk 4y ago
The good news from over the last few years is that both American- and Russian-made escape systems appear to function as designed.

8 points by _Microft 4y ago

Mentioned this in another thread on the fail, the live feed claims the capsule landing was softened by retrothrusters firing before impact. Stepping through the YouTube video frame by frame I see no sign of that... ...did they walk this back yet? Or is just poor video? (I don't think so but it's possible...)

egberts1 4y ago
And boy … what a fiery dust cloud that was stirred up by its seemingly harsh landing.
_Microft 4y ago
From what I know the retrothrusters ignite in the very last moment. The cloud of dust could well be from that, not only from the impact. Soyuz capsules also soften the landing like that. From what I remember Soyuz ignites its retro rockets less than 1m above ground [0]. [0] https://youtu.be/CYqW0rDEjnE?t=140 https://youtu.be/CYqW0rDEjnE?t=140
- aaroninsf 4y ago
  I cannot imagine thrust initiated in the last tens of milliseconds being able to ramp up and operate sufficiently to cause meaningful deceleration, and also cannot see how this could do more than "round off" the deceleration curve (lower the spike of force/stress). I take your word for it, I just... can't imagine. That's a failure I guess of imagination and reasoning by analogy instead of looking at the math. It sounds like trading being punched with impact for being punched by 10ms of thrust then a slightly softer punch of impact!
  - _Microft 4y ago
    Apologies for the late reply. If the retro rockets make the deceleration take twice or three times as long, then the acceleration is only half or a third of the impact without braking. That's most likely quite an improvement. I do not know any details about the retro rockets of Blue Origin's capsule or Soyuz but here is some information about the system that SpaceX uses for their launch escape system. The Crew Dragon capsule has eight SuperDraco [0] engines meant to push it away from a failing rocket. These engines have 71kN thrust (16000 lbf) each and reach full thrust a mere 100ms after ignition. [0] https://en.wikipedia.org/wiki/SuperDraco https://en.wikipedia.org/wiki/SuperDraco

themadturk 4y ago

The good news from over the last few years is that both American- and Russian-made escape systems appear to function as designed.