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That was great! The guys said at the beginning that they are expecting Falcon to blow up because aerodynamics change significantly once the nose separates. St

That was great! The guys said at the beginning that they are expecting Falcon to blow up because aerodynamics change significantly once the nose separates. Stupid question, couldn't they just give Falcon it's own nose so that it doesn't blow up after dragon separates? Dragon could have been mounted on that nose.

Ndymium 7y ago
I would imagine the escape system is only used when there is something very wrong with the flight. In that case there is usually no hope of recovering the rocket anyway (if it didn't explode, could it make it to the landing site?). The added weight and complexity probably make this a bad trade-off.
- skykooler 7y ago
  I remember seeing someone tackle that question on /r/spacex; the consensus was that, while a first stage booster can return on its own, if it has a full second stage attached the extra mass is too much for the legs (it normally lands nearly empty) and the extra length causes aerodynamics issues (the gridfins should be at the top of the rocket but in that scenario there's quite a bit of rocket above them).
nrb 7y ago
In the event an in-flight abort becomes necessary, odds are that the craft is probably going to be lost no matter what. Adding additional complexity or weight for a vanishingly unlikely scenario likely isn't worth it to them.
LeonM 7y ago
> Stupid question, couldn't they just give Falcon it's own nose so that it doesn't blow up after dragon separates? Dragon could have been mounted on that nose. There are no stupid questions. The abort system is only there as a last resort in case of booster failure. So in a situation where the abort system is fired, the falcon has probably already failed beyond the point where it is expected to be able to land.
51Cards 7y ago
There is a great thread on r/spacex discussing the logistics around trying to save the booster. In the end it was generally agreed not to be possible. A VERY brief summary of reasons from memory: deceleration causes fuel to rise up in the tanks likely rupturing them from hydralic impact alone, lack of thrust even momentarily causes the rocket to become unstable end to end, only 3 engines are equipped to be relightable and may not relight because the fuel would be at the top of the tanks, too much fuel mass to burn off before landing, too much mass with second stage, etc. Elon tweeted out the same, that they played with it and deemed it not possible. As such I beleive the rocket was stripped of landing legs and grid fins too. Was a one way ride only.
- jtms 7y ago
  I’m guessing since this test was not focused on the rocket itself that they just decided it wasn’t a problem worth trying to solve simultaneously with the dragon
  - Tuna-Fish 7y ago
    It's a problem that does not need to be solved. If all goes well, this was the very last time the launch abort system is ever fired. It's an emergency escape system for when things have already gone pear-shaped, and in most cases would only be triggered after the rocket below it has failed in some way.
    - DuskStar 7y ago
      Exactly = even if this isn't the last time the launch escape system is used, it'll almost certainly be the last time it's used to escape from a perfectly good booster.
peterburkimsher 7y ago
I think one of the purposes of the test was to ensure that the crew can escape safely from a dramatic fireball. It's hard to simulate throwing shrapnel and fuel at the Dragon capsule without actually blowing up the booster. However, the Falcon wasn't intentionally detonated! This was also by design; if explosive charges were placed down the side and made it come apart naturally, it would come apart in a predictable way. If you know anything about test-driven development, someone would try to made assumptions about the explosion. By allowing an uncontrolled explosion at the time when the Falcon is experiencing the most extreme aerodynamic forces, it's basically creating a worst-case scenario. SpaceX successfully proved that the Dragon capsule can escape from that worst-case, and that's great news. It'll be flying with crew very soon, I think.

Ndymium 7y ago

I would imagine the escape system is only used when there is something very wrong with the flight. In that case there is usually no hope of recovering the rocket anyway (if it didn't explode, could it make it to the landing site?). The added weight and complexity probably make this a bad trade-off.

skykooler 7y ago
I remember seeing someone tackle that question on /r/spacex; the consensus was that, while a first stage booster can return on its own, if it has a full second stage attached the extra mass is too much for the legs (it normally lands nearly empty) and the extra length causes aerodynamics issues (the gridfins should be at the top of the rocket but in that scenario there's quite a bit of rocket above them).

nrb 7y ago

In the event an in-flight abort becomes necessary, odds are that the craft is probably going to be lost no matter what. Adding additional complexity or weight for a vanishingly unlikely scenario likely isn't worth it to them.

LeonM 7y ago

> Stupid question, couldn't they just give Falcon it's own nose so that it doesn't blow up after dragon separates? Dragon could have been mounted on that nose. There are no stupid questions. The abort system is only there as a last resort in case of booster failure. So in a situation where the abort system is fired, the falcon has probably already failed beyond the point where it is expected to be able to land.

51Cards 7y ago

There is a great thread on r/spacex discussing the logistics around trying to save the booster. In the end it was generally agreed not to be possible. A VERY brief summary of reasons from memory: deceleration causes fuel to rise up in the tanks likely rupturing them from hydralic impact alone, lack of thrust even momentarily causes the rocket to become unstable end to end, only 3 engines are equipped to be relightable and may not relight because the fuel would be at the top of the tanks, too much fuel mass to burn off before landing, too much mass with second stage, etc. Elon tweeted out the same, that they played with it and deemed it not possible. As such I beleive the rocket was stripped of landing legs and grid fins too. Was a one way ride only.

jtms 7y ago
I’m guessing since this test was not focused on the rocket itself that they just decided it wasn’t a problem worth trying to solve simultaneously with the dragon
- Tuna-Fish 7y ago
  It's a problem that does not need to be solved. If all goes well, this was the very last time the launch abort system is ever fired. It's an emergency escape system for when things have already gone pear-shaped, and in most cases would only be triggered after the rocket below it has failed in some way.
  - DuskStar 7y ago
    Exactly = even if this isn't the last time the launch escape system is used, it'll almost certainly be the last time it's used to escape from a perfectly good booster.

peterburkimsher 7y ago

I think one of the purposes of the test was to ensure that the crew can escape safely from a dramatic fireball. It's hard to simulate throwing shrapnel and fuel at the Dragon capsule without actually blowing up the booster. However, the Falcon wasn't intentionally detonated! This was also by design; if explosive charges were placed down the side and made it come apart naturally, it would come apart in a predictable way. If you know anything about test-driven development, someone would try to made assumptions about the explosion. By allowing an uncontrolled explosion at the time when the Falcon is experiencing the most extreme aerodynamic forces, it's basically creating a worst-case scenario. SpaceX successfully proved that the Dragon capsule can escape from that worst-case, and that's great news. It'll be flying with crew very soon, I think.