SpaceX Performs Successful Dragon Pad Abort Test

SpaceX performed a successful pad abort test at Cape Canaveral this morning. The capsule rocketed skyward using Super Draco abort motors and then splashed down at sea. The test was not completely nominal; the vehicle didn’t reach as high as expected.

The video above is long. Skip ahead to about 15 minutes to catch the final countdown and abort test.

Here’s a shorter version of the video.

  • DavidR2015

    Short and sweet…

  • Andrew Tubbiolo

    Wow, and they used their pad they flew from last week, and will fly from again in a few weeks. Well done again Space X. All the more pressure to bring to bear to reform the primes. Good times indeed.

  • Kirk

    Here is a replay of the NASA video (which does a better job tracking the launch).

    While certainly a successful abort test, performance doesn’t appear to have been quite up to expectations. A small puff of smoke, about one second before the larger puff at thruster shutdown, suggests that one or two thrusters shut down prematurely.

    As was emphasized at the press conference, this was a test.

  • Snofru Chufu

    I am surprized to see this low acceleration (only 4-5 g’s based on SpaceX data). I hope this high enough in case of an exploding rocket. Soyuz’s LES reaches 14-17 g’s (Wiki). I assume also Apollo’s and Orion’s LES exhibit higher escape accelerations. The test did also not achieved the projected downrange of 2.2 km. It was much shorter, it landed nearly on land.

  • Hug Doug

    SpaceX’s abort system burns for 6 seconds, so it can get away from a failing rocket while experiencing lower g forces.

    Other abort systems fired for shorter periods of time (2-3 seconds), so higher g forces were experienced.

    I think windy conditions pushed the capsule closer to land than they would have liked.

    Splashdown velocity looked fine to me. Apollo speed at splashdown was about 30 mph.

  • DavidR2015

    Having a look at Google maps, I would estimate that the capsule traveled around 1200m downrange.
    Looking at Kirk’s NASA video above, apogee appears to have occurred around 18s. Apogee was planned to occur somewhere between 15 and 21s.
    Looking at the Spacex video, splashdown occured at 1 min 39s (99s) or so. It was sheduled to splashdown at T+107s.
    So the degree to which the test was off-nominal was small, and I think that the emphasis on “what went wrong” which is being splashed around in the media at the moment is misplaced. The evidence that is in the public domain at the moment suggests that the test was near perfect.

  • Geobram

    I wouldn’t want to be in that capsule. That dummy is shaken and stirred 😉 Still better than blown to bits though.

  • Snofru Chufu

    Long burn times and final velocity are not the most important requirement in such escape situation. The most important requirement is clearly a very high initial acceleration or a minimum time to reach the first 100 or 200 m distance to the exploding rocket. It surprised me that NASA excepts this scenario with that low acceleration.
    Splash-down: It is only my personal visual impression, which displays a bit harsher too me as Apollo splash-downs.

  • Hug Doug

    The initial “escape distance” looked fine to me. It’s well above the lightning towers in the first two seconds. After that the idea is to get downrange from the failing rocket, and it also did that.

  • Snofru Chufu

    No discussion:15 g are much better 5 g with a exploding rocket under the seat.

    BTW, it seems that they need the heavy drunk for aerodynamic stabilization.

  • Andrew Tubbiolo

    Don’t forget the goal is to escape shrapnel from an exploding rocket and also escape and get clear of the spilled propellant plume. 12g might not be required. If you watch the Soyuz booster failure/escape success they had plenty of time to escape the disaster and were beyond well clear of the fireball when they decided escape.

    https://www.youtube.com/watch?v=UyFF4cpMVag

    I can’t say I’ve done the research on the problem to say that 5g is too little, or that a 12g is too much. However the problem was given some review before Dragon V2’s capabilities were defined. My bet is it’s enough.

  • Hug Doug

    Yes discussion. If the capsule can get clear with 5 g acceleration it’s much better. Certainly much more comfortable for the crew, and poses far less risk of injury to them.

    Trunk is very lightweight, actually, since it’s basically an empty can. It’s the fins on it that gave it aerodynamic stability.

  • Andrew Tubbiolo

    Have you tried pulling 5g? I highly suggest it. Go to your nearest muni airport. Look up an FBO for someone who teaches aerobatics to licensed pilots. Have him take you up. It’ll cost about $150 bucks. Have him take you thru, 2, 4, then 5 g. Then ask yourself if you want to experience twice that unless you REALLY have to. Not to mention you’ll have a lot of fun.

  • DavidR2015

    Worth noting, that Falcon 9 V1.0 lifted about 12 tons to LEO. Dragon carries something like 6 tons of cargo, so the empty cargo dragon weighs something like six tons.
    Assuming that the crewed dragon empty weight is similar to the cargo dragon, the what flew today weighed around 6 tons, about 12,000 lbs.
    Superdraco full power is rated at 120,000lbs for all eight engines. That would produce around 10g’s of acceleration in a Launch escape scenario.
    Today’s test, we were told that Dragon would do 0-100mph in around one second, that’s about 4g’s of acceleration, and because it is travelling straight up, we have to add one g for gravity.
    This back of a fag packet calculation suggests that today’s test featured engines on the crewed dragon that were limited to about 50% power.
    Why would Spacex do this? I’m not sure, maybe because its a test it makes sense to run things a bit slower, and not put such high g forces on components, in order to do as well in the test as possible. You can test components for full intensity in the lab or at a later date.
    The idea that Crewed Dragon can only pull 5g’s of acceleration is disturbing if you consider a launch abort late in the launch process. As the rocket nears orbit, it is likely to be accelerating at around 3g’s. Having 5g’s of performance makes it essential that you can shut down the main engine on the rocket before you abort, otherwise you won’t get very much separation at all, due to the similar accelerations of the Dragon, and the second stage if its payload had been jettisoned.
    As a result of today’s test, I suspect that the Dragon launch escape system has a much higher level of performance than was demonstrated today.
    Maybe the lower power makes it easier for Spacex to maximise the probability of getting paid the milestone by NASA.

  • Hug Doug

    It was weighted on the inside to simulate a max-capacity crew. You can see the steel plates bolted to aluminum frames here:

    http://www.nasaspaceflight.com/wp-content/uploads/2015/05/2015-05-05-235317-350×231.jpg

  • Snofru Chufu

    Comfortable for crew, killed already by the launcher?

  • Snofru Chufu

    “As a result of today’s test, I suspect that the Dragon launch escape system has a much higher level of performance than was demonstrated today.”

    Hoppefully! 🙂 Thanks for detailed consideration.

  • therealdmt

    Woo hoo!

  • Snofru Chufu

    In case of being death or alive you will accept also 15 g for a second as the Russian cosmonauts did.

  • Hug Doug

    His post is based on an incorrect premise. See my reply.

  • Hug Doug

    … read what I wrote.

    If you can get away safely, then 5 g is preferable. Apollo had to get away from the enormous Saturn V rocket. The Falcon 9 is much smaller.

  • Snofru Chufu

    It is shame to see in this case that LES was activated so late. Why did they wait so long? The launcher was already losed after appearance of first flames. Every spilt of a second the booster could explode. I would say we see here an erroneous behavior and much luck.

  • Andrew Tubbiolo

    Have you done the analysis or are you familiar with the problem enough to know that 15g is required? Or are you asserting more is better?

  • Jim R

    “I am surprised to see this low acceleration”: CST-100 would have a similar acceleration (4 x 39,000 pounds abort engine vs 8 x 16,000 pounds SuperDraco), so clearly not a problem for NASA.

  • therealdmt

    I had similar impressions — it landed a bit closer to shore than I would have liked. I could see strong onshore winds blowing the capsule back over land. And that splashdown was pretty hard — if that thing lands on land, the crew gonna be in a world of hurt!

    Still, it basically looked good. It got it up and then out to sea, under control. The chutes deployed, it splashed down. It floated rightside up.

  • Snofru Chufu

    Do you have also the number of the other LES’s (BO, Orion, Apollo). Thank you.

  • Larry J

    We don’t know the flight profile well enough to determine if an engine shut down early on its own or if that was planned. Pressure fed hypergolic engines are pretty simple – open the propellant feeds and they go.

  • Snofru Chufu

    A general comment to SpaceX: I have no problems if a test shows some smaller and larger problems. That is normal and for that purpose tests are performed. However, I do not like SpaceX’s or Musk’s bragging and style of advertising. That’s why I like it to look for weaknesses in their designs.

  • Larry J

    I heard the winds were over 20 MPH during the test but don’t know the direction. That is strong enough to effect the downrange distance and impact velocity. At impact with the water, you’d have a substantial horizontal component in addition to the vertical velocity.

  • Larry J

    Yes, the engines only burn for a few seconds. After that, the trunk fins provide the required stabilization. Without the fins, the capsule would likely tumble.

  • Geobram

    Will the dragon always escape with that trunk? What if it is going to escape without the extra trunk in an emergency? Without the aerodynamic stability it seems to roll every way.

  • Snofru Chufu

    Yes, the capsule did tumble significantly after trunk separation, just before pilot parachutes release. Intended or not?

  • Snofru Chufu

    I am asking only and compare observed behavior to existing designs as that of Soyuz, Orion and Apollo.

  • Hug Doug

    Yes, it will always have to abort with the trunk.

  • Jim R

    Blue Origin: No idea. Orion: 400,000 pounds. Apollo: Between 147,000 and 200,000 pounds.

  • Snofru Chufu

    I just viewed the BO video. The ascent looks also faster as that from today and it needs no additional aerodynamic means for stabilization.

  • Snofru Chufu

    Thanks.

  • Hug Doug

    At that time, activation of the Soyuz launch abort system when the rocket was still on the ground required the input of commands from two separate ground controller stations. The crew in the capsule could not initiate an abort and the automatic abort system on the rocket was not yet active. However, the cables connecting the ground controllers to the rocket had burned through before the command to abort could be given. They had to switch to a back-up system using signals sent from a range control station 30 kilometers away. The back-up launch abort procedures took 20 seconds to perform, and the signals got there just in time to get the crew to safety.

  • HyperJ

    Don’t be so childish. You really feel that you need to counter Elon hype with your armchair engineering? Really?

  • Jim R

    Note Blue Origin’s capsule is for their suborbital system, so probably not a good comparison to Dragon. As for Orion LES, its high acceleration is probably designed to get away from an out of control solid booster (originally Ares I, SLS has solids too).

  • Michael Vaicaitis

    What if the trunk is filled with 3 tonnes of cargo?. Or perhaps it is not the intention to combine crew with unpressurised cargo?.

    I’m not seeing why “aerodynamic stability” is required. While the engines are burning, they are also steering. Once the engines stop, who cares about a low g tumble or two?.

  • Snofru Chufu

    1200 m downrange are 1000 m shorter as expected. It doubt that it comes only from wind influence.

  • Snofru Chufu

    I do not see what childish means in this context? I see only that this test flight brought a number questions to the table, which shall be discussed. Nobody shall loss his critical thinking only because Godfather Musk was involved. BTW, was there a similar hype about similar test conducted by BO years ago? No. Only silence and at least some laughter. I am not sure that this toxic, hypergolic, complex bipropellant propulsion system is a good idea for this application.

  • Snofru Chufu

    I recalled that there were some problems, but I forgot the details. Thank you for updating myself and searching.

  • HyperJ

    What is childish is that you feel the need to post just because you don’t like how he promotes himself, as if you will somehow balance it. That is childish, and I stick by that.

    Also, your same sentiments could have been said by anyone when gasoline engines overtook steam engines. It is a great idea for this application since the same amount of propellant can be used for abort, in space maneuvers, and landing. It seems like a pretty elegant solution.

  • Andrew Tubbiolo

    It’s a fair question. And we know Space X is willing to wipe the slate clean of assumptions. Space X will have a disaster one day. I think we’ll get to see their escape system in action. Also keep in mind, if there’s a heroic solution to a problem. The Russians will take the heroic solution every time. If it came out that the Russians thought of 1 situation where 15g was required, and 25 where 5 would suffice, and they took the 15g solution. I would not be surprised at all. We suffer from the same disease. If you look at some of the early shuttle concepts, you’ll see some very sane designs meant to be steps in an evolution. We can fall into heroism too. Being a wimp is sometimes perfectly okay, and is usually cheaper and less risky.

  • Hug Doug

    The fins provide stability for the coast phase, after powered flight has ended. You can see that once the capsule separates from the trunk, , it immediately starts to tumble.

    Apparently the SpaceX engineers care.

  • Snofru Chufu

    I would say Musk’s behavior and “style” is often childish. I deleted my comment’s part about the hypergolic system, because it is not my main point on the subject of this test.

    However, you responded already, so I will give an answer. I think a very important safety system of this kind shall exist be separated from other propulsion task and not mixed up.

    Yes, I breathed solid rocket exhaust and I breathed by the way even N2O4 and hydrazine fumes, my dear armchair fellow. It is also wrong to think a solid rocket is old technology as a steam-engine and a hypergolic liquid system is new technology as a gasoline engine. That is complete nonsense. That are very different technologies, both have its right to exist and its technological development.

    However, in many cases solid propellant propulsion replaces older liquid hypergolic systems (statement can be applied to more or less all missile systems). By the
    way, SpaceX (or Musk) is not innovative enough to replace this toxic hypergolic system by non-toxic one.

  • Michael Vaicaitis

    After separation, Dragon tumbles only once before drogue deploy. Looks likely that it would tumble to heavy end first, which being less aerodynamic, might decrease the height and distance reached during the coast.
    Might also be that the trunk can detach from the rocket by pyros?, but that Dragon detaches from the trunk by mechanical release?.

    I don’t doubt that the SpaceX engineers have thought this all through. The fins certainly do scream aero stabilisers and no other nominal mission scenario occurs to me that might require those fins. I still wonder though, are those fins to stop Dragon tumbling during coast, or are they there to stop Dragon+trunk tumbling before the trunk can be detached?. It don’t matter either way, but still I’m curious.

  • Hug Doug

    My point is it starts to tumble right away. Blunted cones seek stable flight, which is blunt end first, and you’re right, this is a high-drag orientation. This would happen immediately after the SD engines stop firing, except for the fins on the trunk. They do want a smooth coast phase so they can get as far away from an exploding rocket as possible.

    The hinged bit you saw has the electrical and other data connections to the trunk, which will have the solar arrays on it. The rest of it does separate by the firing of explosive bolts, as it has on the Cargo Dragon.

    “are those fins to stop Dragon tumbling during coast, or are they there to stop Dragon+trunk tumbling before the trunk can be detached?”

    I think those are two sides of the same coin, the fins definitely perform both functions.