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They didn't scrap it exactly, they just relegated its function to use as an emergency propulsive abort system. But the Dragon 2 still has the super dracos... an

They didn't scrap it exactly, they just relegated its function to use as an emergency propulsive abort system. But the Dragon 2 still has the super dracos... and one of them exploded, causing the loss of a test vehicle, a few months ago, which has resulted in timeline setbacks to the program. It doesn't seem like reliability has been a walk in the park there either.

waiseristy 7y ago
The super draco didn't explode fyi, it was the fueling system.
- wolfram74 7y ago
  An interesting distinction, like saying "the engine didn't explode, the gas tank did" but one wouldn't be there except for the other. I suppose for properly fixing the problem it's important to say one vs the other, but in general conversation it could come off as a pedantic?
  - waiseristy 7y ago
    Well, yes. Pedantic as it may be, the fueling systems seem to be a recurring theme for SpaceX, not their motors. Remember Amos-6?
    - Klathmon 7y ago
      Both failures may have had something to do with "fuel", but they aren't in any way related. The Crew Dragon abort test anomaly was caused by a problematic valve leaking oxidizer "backwards" into the helium tubes which are used to pressurize the system right before ignition. The second they pressurized, it sent a huge amount of oxidizer into the engine where there should have only been helium at the time which caused the explosion. The AMOS-6 anomaly was caused by LOX pooling and working it's way into the liner of a COPV inside the LOX tank. The LOX got into the fibers, and a small amount of friction ignited the oxygen and caused the "boom". They may seem similar in that they are both related to the oxidizers getting somewhere they shouldn't and igniting, but a rocket is pretty much just a tube of carefully controlled fuel and oxidizer and a nozzle to shoot it out. Of course most problems are probably going to result in fuel or oxidizer getting somewhere it shouldn't, and when that happens they are going to explode. For laypeople the exact reason why the fuel and oxidizer mixed at the wrong time isn't really important, but don't fall into the trap of thinking that the 2 are related.
      - waiseristy 7y ago
        So at this point who is being the pedantic one? Lol!
        Klathmon 7y ago
        It's not being pedantic if you are correcting the conclusion. You mentioned that fueling system issues have been a recurring theme in failures, and I just wanted to point out that it's not really correct. Even though the 2 failures looked somewhat similar from the outside, they actually had basically nothing in common.
        waiseristy 7y ago
        I think I was also "correcting a conclusion"? A fuel system exploding and a rocket motor exploding are 2 failures that look somewhat similar from the outside, but in reality have nothing in common other than that they rely on one another. We are both arguing pedantics
        Klathmon 7y ago
        I was just sharing information that I found interesting which kind of contradicted your claim that fueling was a common source of issues for SpaceX. I find this stuff super interesting, and I figured others might as well. I'm not trying to argue or get in internet fights here, I just like talking about space stuff.
        waiseristy 7y ago
        Same, and I thought it was important to point out that the Draco motor has so far been reliable in testing. The fuel systems seem to be tricky regardless of their failure modes: mechanical, or as you pointed out for Amos-6, material. I too like talking about space stuff, I just think it's deconstructive to call out some random poster on the internet as pedantic lol
  - SEJeff 7y ago
    Well an engine explosion and a gas tank explosion are very difference failure modes, and in rockets, pedantics matter.

waiseristy 7y ago

The super draco didn't explode fyi, it was the fueling system.

wolfram74 7y ago
An interesting distinction, like saying "the engine didn't explode, the gas tank did" but one wouldn't be there except for the other. I suppose for properly fixing the problem it's important to say one vs the other, but in general conversation it could come off as a pedantic?
- waiseristy 7y ago
  Well, yes. Pedantic as it may be, the fueling systems seem to be a recurring theme for SpaceX, not their motors. Remember Amos-6?
  - Klathmon 7y ago
    Both failures may have had something to do with "fuel", but they aren't in any way related. The Crew Dragon abort test anomaly was caused by a problematic valve leaking oxidizer "backwards" into the helium tubes which are used to pressurize the system right before ignition. The second they pressurized, it sent a huge amount of oxidizer into the engine where there should have only been helium at the time which caused the explosion. The AMOS-6 anomaly was caused by LOX pooling and working it's way into the liner of a COPV inside the LOX tank. The LOX got into the fibers, and a small amount of friction ignited the oxygen and caused the "boom". They may seem similar in that they are both related to the oxidizers getting somewhere they shouldn't and igniting, but a rocket is pretty much just a tube of carefully controlled fuel and oxidizer and a nozzle to shoot it out. Of course most problems are probably going to result in fuel or oxidizer getting somewhere it shouldn't, and when that happens they are going to explode. For laypeople the exact reason why the fuel and oxidizer mixed at the wrong time isn't really important, but don't fall into the trap of thinking that the 2 are related.
    - waiseristy 7y ago
      So at this point who is being the pedantic one? Lol!
      - Klathmon 7y ago
        It's not being pedantic if you are correcting the conclusion. You mentioned that fueling system issues have been a recurring theme in failures, and I just wanted to point out that it's not really correct. Even though the 2 failures looked somewhat similar from the outside, they actually had basically nothing in common.
        waiseristy 7y ago
        I think I was also "correcting a conclusion"? A fuel system exploding and a rocket motor exploding are 2 failures that look somewhat similar from the outside, but in reality have nothing in common other than that they rely on one another. We are both arguing pedantics
        Klathmon 7y ago
        I was just sharing information that I found interesting which kind of contradicted your claim that fueling was a common source of issues for SpaceX. I find this stuff super interesting, and I figured others might as well. I'm not trying to argue or get in internet fights here, I just like talking about space stuff.
        waiseristy 7y ago
        Same, and I thought it was important to point out that the Draco motor has so far been reliable in testing. The fuel systems seem to be tricky regardless of their failure modes: mechanical, or as you pointed out for Amos-6, material. I too like talking about space stuff, I just think it's deconstructive to call out some random poster on the internet as pedantic lol
- SEJeff 7y ago
  Well an engine explosion and a gas tank explosion are very difference failure modes, and in rockets, pedantics matter.