7 ms·

SpaceX Grasshopper 744m test flight [video]

171 points by nkoren 13y ago

GuerraEarth 13y ago
RLV Grasshopper is well named.
ChuckMcM 13y ago
744 meters is just over 2,440 feet, I wonder what they are doing to deal with the spin issue from the Falcon9 flight out of Vandenberg. Watching this makes me feel the same way I did seeing the DC-X take off and land which is make me feel like "real" science fiction rockets are about to be realized.
- InclinedPlane 13y ago
  Apparently simply having landing legs on the stage (and extending them) will be enough to stabilize the spin problem sufficiently to allow it to be controllable by the RCS et al.
  - revelation 13y ago
    Since you've been likely keeping up with this, has there been any video released on the fate of the return stage? Musk mentioned they would put something out there, but it doesn't seem to have materialized yet.
  - ChuckMcM 13y ago
    I realize that Elon speculated that would be the case, but I wasn't neccesarily buying his explanation. Two things need additional color, one being given the lack of atomosphere at the altitude where the first stage separates (tapes put it at just over 3 minutes into the flight), and two structural integirty of those struts making the atmospheric transition. So you need to get the retro burn off while you are exo-atmospheric or you risk melting off the important bits when you re-enter. That suggests that you need some sort of RCS to cut rotational dynamics so that you can stage for retro, then re-enter at less than hypersonic velocity. Further you can't do you retro burn until you've allowed the upper stage to clear. Another interesting bit is that the first stage appears to have cameras, they were showing video from them during the launch, but we've not seen the post separation video. I hope that video surfaces at some point as it could help design something to mitigate the whole roll thing before it got out of hand.
    - coob 13y ago
      Musk has mentioned posting that video online[1]. [1] http://www.reddit.com/r/spacex/comments/1ne36t/partial_success_for_falcon_9_first_stage_reentry/ http://www.reddit.com/r/spacex/comments/1ne36t/partial_succe...
      - novalis78 13y ago
        great resource thanks. Looks like the first test with legs is going to be in FL.
- lyndonh 13y ago
  I thought the spin problem was a non issue: they just wanted to see if they could relight the engine when Falcon is falling back to earth at speed. When it's relit they can compensate the spin and take control.
  - ChuckMcM 13y ago
    The challenge was that with the stage spinning they couldn't feed fuel to the engines to finish the retro burn. That is an issue. They need to work around that in the next attempt (either by not spinning or by allowing for it with a different fuel feed mechanism)
    - XorNot 13y ago
      Increasing tank pressurization would mitigate it, but I suspect it's a lot easier to plan to control the spin.
      - ChuckMcM 13y ago
        It is a fascinating problem, you launch with one type of space craft and then you recover with a different craft (in terms of mass distribution, fuel supply, etc). I'd love to hear how the avionics deals with the two systems. especially given that most of the rocket systems I've seen internal descriptions of are very narrowly tuned to be critically damped around their launch parameters. Unlike say aircraft that are dealing with fuel weight management issues and load balancing. I know Elon said he would release the videos, and I'm sure they will, this is definitly the kind of 'rocket science' that is very intriguing to me.
dhughes 13y ago
As fantastic as that was I can't help but think that now I want a quadcopter with an HD video camera on it.
- JshWright 13y ago
  Start with a tricopter. They're a lot more fun to fly. http://www.youtube.com/watch?v=YCPMC_fiSMI http://www.youtube.com/watch?v=YCPMC_fiSMI
- tgb 13y ago
  Anyone know what models and price ranges can get to altitudes like that? And how are these controlled - if manually in real-time what kind of connection is needed?
  - ivarvong 13y ago
    I think this was shot with a DJI S800. The RC link to fly it is usually 2.4GHz. A separate link, often at 5.8GHz, is used to send the camera feed back to the ground to help the pilot or compose the shot, or both.
    - stevenrace 13y ago
      Good eye ID'ing the distinctive DJI arms on the hexacopter. The convention seems to be 2.4Ghz for telemetry back the to base-station or radio display - and something lower in the UHF band like 433 or 900Mhz for actual control. Mainly because Zigbee/802.15.4 radios are readily available in 2.4Ghz and 433Mhz goes a lot further (and through more things) by comparison at 1W. [/sitting next to 3 hexacopters at the moment]
      - NickNameNick 13y ago
        What kind of transmitter are you using for manual control? I assume you aren't using a ground station all the time... I only ask because most new 'brand name' (JR, Futaba, Airtronics, Robbe) tramsitters seem to be 2.4Ghz. I know FM radios are still available on 36 and 40 Mhz, among others, but I haven't seen many used for a while with new aircraft.
kcorbitt 13y ago
This is really exciting technology, but as far as I can tell not even SpaceX is sure that it will be practical to include it in a production rocket (https://www.youtube.com/watch?v=IIVCCaYWGpk https://www.youtube.com/watch?v=IIVCCaYWGpk). That's not meant as a criticism though -- the fact that they're willing to try anyway already brings them to legendary status in my book.
- cryptoz 13y ago
  It doesn't matter to them that they think it might fail. The only reason that SpaceX exists is to colonize Mars, and the only way to do that is with reusable spaceships. The reason they're willing to try it is the same reason they were willing to build non-reusable rockets to start: it's the only way forward.
- cfreeman 13y ago
  Elon appears to be pretty confident after they tested booster return on the last Falcon 9 flight. See this tweet: https://twitter.com/elonmusk/status/384407846349062144 https://twitter.com/elonmusk/status/384407846349062144
- rajivtiru 13y ago
  You're pretty much right. This has no production value. This is great "look at this thing that we can do" video but the reason no one else attempts it is because there is no next step. They didn't just stop at 744 meters for no reason, fuel is the limitation here. It is impossible(unless you want to build something the size of Saturn V again) to put enough fuel on a launch vehicle to carry a satellite to orbit and then land it back like this. I don't have the exact data, but as an guesstimate it would take twice as much fuel(fuel + "return fuel") to land the rocket back like this. We also need to put in extra fuel to take the "return fuel" up there in the first place...you get the idea. Extremely un-economical. I do not see a next step for grasshopper because building another rocket is cheaper than returning the engine back like this.
  - voodoomagicman 13y ago
    The idea is not to slowly fly to orbit and back - it is for the stages to fall to earth and then decelerate from terminal velocity to a gentle landing. The reason for these tests is to develop the technology required to do that. According to Musk, fuel accounts for only 0.3% of the costs of a launch, so a re-usable rocket could achieve significant cost savings even though it would require more fuel.
bane 13y ago
That may have been the coolest cinematography of a real piece of space hardware I've ever seen. One robotically controlled flying camera shooting and flying around a reusable spaceship, both right out of sci-fi.
- flippyhead 13y ago
  More often I feel that I'm living in the future.
- girvo 13y ago
  I didn't read about what it was supposed to do before I watched the video. Seeing it stop in mid-air then land perfectly... wow. It actually gave me chills. That's some year 2213 shit, here, now. Amazing.
deletes 13y ago
Did you notice how the rocket tilted to correctly position itself over the landing strip. Great camera angle.
6ren 13y ago
This is so cool, it looks CGI. Unbelievable. At first I thought the camera was in a helicopter, but a drone makes more sense (and is even cooler). Elon Musk is Tom Swift.

171 points by nkoren 13y ago

RLV Grasshopper is well named.

744 meters is just over 2,440 feet, I wonder what they are doing to deal with the spin issue from the Falcon9 flight out of Vandenberg. Watching this makes me feel the same way I did seeing the DC-X take off and land which is make me feel like "real" science fiction rockets are about to be realized.

InclinedPlane 13y ago
Apparently simply having landing legs on the stage (and extending them) will be enough to stabilize the spin problem sufficiently to allow it to be controllable by the RCS et al.
- revelation 13y ago
  Since you've been likely keeping up with this, has there been any video released on the fate of the return stage? Musk mentioned they would put something out there, but it doesn't seem to have materialized yet.
- ChuckMcM 13y ago
  I realize that Elon speculated that would be the case, but I wasn't neccesarily buying his explanation. Two things need additional color, one being given the lack of atomosphere at the altitude where the first stage separates (tapes put it at just over 3 minutes into the flight), and two structural integirty of those struts making the atmospheric transition. So you need to get the retro burn off while you are exo-atmospheric or you risk melting off the important bits when you re-enter. That suggests that you need some sort of RCS to cut rotational dynamics so that you can stage for retro, then re-enter at less than hypersonic velocity. Further you can't do you retro burn until you've allowed the upper stage to clear. Another interesting bit is that the first stage appears to have cameras, they were showing video from them during the launch, but we've not seen the post separation video. I hope that video surfaces at some point as it could help design something to mitigate the whole roll thing before it got out of hand.
  - coob 13y ago
    Musk has mentioned posting that video online[1]. [1] http://www.reddit.com/r/spacex/comments/1ne36t/partial_success_for_falcon_9_first_stage_reentry/ http://www.reddit.com/r/spacex/comments/1ne36t/partial_succe...
    - novalis78 13y ago
      great resource thanks. Looks like the first test with legs is going to be in FL.
lyndonh 13y ago
I thought the spin problem was a non issue: they just wanted to see if they could relight the engine when Falcon is falling back to earth at speed. When it's relit they can compensate the spin and take control.
- ChuckMcM 13y ago
  The challenge was that with the stage spinning they couldn't feed fuel to the engines to finish the retro burn. That is an issue. They need to work around that in the next attempt (either by not spinning or by allowing for it with a different fuel feed mechanism)
  - XorNot 13y ago
    Increasing tank pressurization would mitigate it, but I suspect it's a lot easier to plan to control the spin.
    - ChuckMcM 13y ago
      It is a fascinating problem, you launch with one type of space craft and then you recover with a different craft (in terms of mass distribution, fuel supply, etc). I'd love to hear how the avionics deals with the two systems. especially given that most of the rocket systems I've seen internal descriptions of are very narrowly tuned to be critically damped around their launch parameters. Unlike say aircraft that are dealing with fuel weight management issues and load balancing. I know Elon said he would release the videos, and I'm sure they will, this is definitly the kind of 'rocket science' that is very intriguing to me.

dhughes 13y ago

As fantastic as that was I can't help but think that now I want a quadcopter with an HD video camera on it.

JshWright 13y ago
Start with a tricopter. They're a lot more fun to fly. http://www.youtube.com/watch?v=YCPMC_fiSMI http://www.youtube.com/watch?v=YCPMC_fiSMI
tgb 13y ago
Anyone know what models and price ranges can get to altitudes like that? And how are these controlled - if manually in real-time what kind of connection is needed?
- ivarvong 13y ago
  I think this was shot with a DJI S800. The RC link to fly it is usually 2.4GHz. A separate link, often at 5.8GHz, is used to send the camera feed back to the ground to help the pilot or compose the shot, or both.
  - stevenrace 13y ago
    Good eye ID'ing the distinctive DJI arms on the hexacopter. The convention seems to be 2.4Ghz for telemetry back the to base-station or radio display - and something lower in the UHF band like 433 or 900Mhz for actual control. Mainly because Zigbee/802.15.4 radios are readily available in 2.4Ghz and 433Mhz goes a lot further (and through more things) by comparison at 1W. [/sitting next to 3 hexacopters at the moment]
    - NickNameNick 13y ago
      What kind of transmitter are you using for manual control? I assume you aren't using a ground station all the time... I only ask because most new 'brand name' (JR, Futaba, Airtronics, Robbe) tramsitters seem to be 2.4Ghz. I know FM radios are still available on 36 and 40 Mhz, among others, but I haven't seen many used for a while with new aircraft.

kcorbitt 13y ago

This is really exciting technology, but as far as I can tell not even SpaceX is sure that it will be practical to include it in a production rocket (https://www.youtube.com/watch?v=IIVCCaYWGpk https://www.youtube.com/watch?v=IIVCCaYWGpk). That's not meant as a criticism though -- the fact that they're willing to try anyway already brings them to legendary status in my book.

cryptoz 13y ago
It doesn't matter to them that they think it might fail. The only reason that SpaceX exists is to colonize Mars, and the only way to do that is with reusable spaceships. The reason they're willing to try it is the same reason they were willing to build non-reusable rockets to start: it's the only way forward.
cfreeman 13y ago
Elon appears to be pretty confident after they tested booster return on the last Falcon 9 flight. See this tweet: https://twitter.com/elonmusk/status/384407846349062144 https://twitter.com/elonmusk/status/384407846349062144
rajivtiru 13y ago
You're pretty much right. This has no production value. This is great "look at this thing that we can do" video but the reason no one else attempts it is because there is no next step. They didn't just stop at 744 meters for no reason, fuel is the limitation here. It is impossible(unless you want to build something the size of Saturn V again) to put enough fuel on a launch vehicle to carry a satellite to orbit and then land it back like this. I don't have the exact data, but as an guesstimate it would take twice as much fuel(fuel + "return fuel") to land the rocket back like this. We also need to put in extra fuel to take the "return fuel" up there in the first place...you get the idea. Extremely un-economical. I do not see a next step for grasshopper because building another rocket is cheaper than returning the engine back like this.
- voodoomagicman 13y ago
  The idea is not to slowly fly to orbit and back - it is for the stages to fall to earth and then decelerate from terminal velocity to a gentle landing. The reason for these tests is to develop the technology required to do that. According to Musk, fuel accounts for only 0.3% of the costs of a launch, so a re-usable rocket could achieve significant cost savings even though it would require more fuel.

bane 13y ago

That may have been the coolest cinematography of a real piece of space hardware I've ever seen. One robotically controlled flying camera shooting and flying around a reusable spaceship, both right out of sci-fi.

flippyhead 13y ago
More often I feel that I'm living in the future.
girvo 13y ago
I didn't read about what it was supposed to do before I watched the video. Seeing it stop in mid-air then land perfectly... wow. It actually gave me chills. That's some year 2213 shit, here, now. Amazing.

deletes 13y ago

Did you notice how the rocket tilted to correctly position itself over the landing strip. Great camera angle.

6ren 13y ago

This is so cool, it looks CGI. Unbelievable. At first I thought the camera was in a helicopter, but a drone makes more sense (and is even cooler). Elon Musk is Tom Swift.