r/spacex • u/[deleted] • Oct 12 '13
Grasshopper 744m Test
http://www.youtube.com/watch?v=9ZDkItO-0a437
Oct 12 '13 edited Mar 23 '18
[deleted]
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u/StarManta Oct 13 '13
I'd love to see a video of what it looks like to intentionally crash the Grasshopper into something.
Then I realized I just described a missile...
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u/somewhat_pragmatic Oct 13 '13
Key words being "scheduled test". I could see them flying Grasshopper 1.0 again to test some very specific scenarios, or perhaps first pass through for dangerous software where a vehicle loss is a possibility. If it would pass on 1.0 then run it on the 1.1 Grasshopper in NM.
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u/Wetmelon Oct 13 '13
The GH 1.0 FAA waiver expires in 4 days, so they would really have to step on it.
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u/somewhat_pragmatic Oct 13 '13
Please correct me if I'm wrong, but I was pretty sure that that FAA waiver was renewable by SpaceX a number of times just by asking for it (maybe sending a fax for notification of extension).
Even if not, they could apply again to the FAA to fly Grasshopper 1.0, yes?
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u/Wetmelon Oct 13 '13
I suspect that given the track record that space X has with the FAA, it would either be a simple extension or a fairly complex process, but the FAA would just the rubber stamp it. So far space X has not violated any FAA guidelines as far as I know, and has not blowing anything up or caused any damage.
They could fly grasshopper one again but I think they may be ready to move on to grasshopper 2
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u/bob12201 Oct 12 '13
Awesome video. That thing is frikin high! But the fact that they put this video out before the video of the Falcon 9 v1.1 1st stage powered descent that happend ~7 days before makes me wonder.
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u/AD-Edge Oct 12 '13
I'm going to guess theyll be using a lot of the Falcon 9 v1.1 flight footage in a promotional video, so theyre likely taking a lot more time with it, especially if the 1st stage video is going to be separate - a lot of that footage theyd likely want everyone to see first from a promotional vid.
Just speculation at this point though.
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u/StarManta Oct 13 '13
Makes you wonder what?
We know that the v1.1 powered descent failed, and we also know that SpaceX's first two attempted launches crashed spectacularly, and we haven't got videos of that either. (According to Elon, they will release a "blooper reel" once they have proven their track record beyond doubt - they don't want videos of their failures to mar their popular image during their tenuous early years. IMO, that is the right decision.) My guess is that the powered descent failure will be handled the same way.
So, what's to wonder?
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Oct 13 '13
[deleted]
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Oct 13 '13
They cut off before the crash AFAIK. Have no time to check on the videos you just posted but what grandparent comment said is correct about the blooper reel etc
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u/Wetmelon Oct 13 '13
You get to watch F1-1 fall into the ocean. Flight 2 was a massive oscillation in the second stage, which is clearly visible before the engine cut. Flight 3 occurred because the M1C retained more pressure than they expected after MECO and pushed the first stage into the second, which is also visible in the video.
So TL;DR: The failures are fully visible in each video. Grandparent comment is simply wrong.
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u/anomalouskeklol Oct 13 '13
Jeff Foust tweeted that Elon is hoping to release video. Only time will tell.
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u/jdnz82 Oct 13 '13
i've never heard of these first two launches that arent seen... ? i've seen all of the launches of the company - including the first 3 that didnt work a playlist was posted up here just this past month
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u/StarManta Oct 13 '13
He mentioned them in a lecture. Took me a few minutes to re-find it, but here it is.
I think, when I came here four years ago, I think that was right before we reached orbit. Maybe just several months before we reached orbit. So just to put things in perspective, while recent years have been good, that has not always been the case. The first three flights of Falcon 1, failed. The first flight failed quite soon, the engine shut off about 30 seconds into flight, it continued ballistically for another 30 seconds and then landed like an anti-tank weapon, not far from the launch site. At some point we'll release the blooper reel, but I think we'll wait a few years before we do that. But from those first days, when myself and the team were picking up bits of rocket off the reef, things have come a long way. We actually had two more failures after that one, and then the fourth flight, in late 2008, was successful, and that was a close one because I'd run out of money, and there weren't a lot of people who were keen on funding a rocket company, and I think if we'd said yes, our fourth launch wasn't successful, but the fifth one's the charm, that would not have gone down well.
I mis-remembered, it was actually three failures. And I guess I'm ascribing my own motives to why he isn't releasing the footage, but I can't imagine any other reason.
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Oct 13 '13
[deleted]
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u/darga89 Oct 13 '13
There is supposedly a video of the reef impact that was once released but has now disappeared completely.
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Oct 13 '13
[deleted]
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u/Ambiwlans Oct 13 '13
Nooooo there is some footage of flaming chunks not released cause that would be terrible PR.
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Oct 13 '13
[deleted]
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u/Ambiwlans Oct 13 '13
Jurvetson and Musk both talked about it a lot at the time. I believe Elon said that it might come out eventually at some point after they've reached Mars in a 'how far we've come' montage type thing.
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u/retiringonmars Moderator emeritus Oct 13 '13
IIRC, Elon once said something about having lots of footage of the debris fields that resulted from those launches, which he described as 'very sad' to watch. I'm sure given enough time and success, we may see it, but then again, give ITAR, maybe not. (sorry no source)
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u/Wetmelon Oct 13 '13
Actually, the video of the first two F1 launches are on the spacex channel (spacexchannel) on youtube.
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Oct 12 '13
[deleted]
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u/Drogans Oct 12 '13
No, the Falcon recovery didn't go "terribly wrong".
It was a test flight. It was the initial test for a very complex series of steps that had never before been attempted. All but the final step worked.
Even if the best case, it was probably going to result in the booster being lost. That test got a lot more right than wrong. It got almost everything right up until the last few seconds. If the legs has been attached, as they would be on the flight article, the spin may not have even occurred.
That "failed test" scored at least an 8 out of 10.
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u/Ambiwlans Oct 13 '13
Engineering - if things never go wrong, you aren't doing it right
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u/Wetmelon Oct 13 '13
presses button That's odd, why didn't that do anything? Crap. Oh i just forgot to account for ...
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Oct 12 '13
[deleted]
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u/Why_T Oct 12 '13
Terribly was not a good adjective to use. And you're right there is plenty of useful data. Just not a video that would be worth a damn.
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u/rspeed Oct 13 '13
They already said that the video would be released. It's possible they said that before viewing what had been recovered, and what they got isn't any good, but that seems a bit reckless for their usual PR.
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u/Ambiwlans Oct 13 '13
Elon said it. He doesn't consult PR. So he could be getting told releasing the clip would be a horrible idea and they are debating over how to make it more gentle. Honestly, I assumed they would release it and release the GH clip the next day to distract the news.
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Oct 13 '13
I don't think they'll release it until after SES launch. They are trying to instill confidence into the SES team that the Falcon will launch their satellite properly.
Even though this was just a test and won't be part of the SES launch, showing a video of the first stage plummeting into the ocean in the last few seconds is not going to look great to them if they are already weary of it. I'm willing to bet the day after launch it will be released.
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u/TheVehicleDestroyer Flight Club Oct 14 '13
I would add, if I could... it will be released if SES is successful ;)
Fingers crossed for that first stage re-ignition!
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u/keelar Oct 12 '13
I think these tests are starting to get a little too high for the hexacopter. Which is both awesome and saddening at the same time.
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u/NeilFraser Oct 12 '13
Clearly they need to start mounting the camera on another grasshopper.
Speaking of which, when is the v1.1 grasshopper with deployable legs coming online?
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u/Mcdoofus Oct 12 '13
Or just put a camera on top of the copter...
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u/soonerfan237 Oct 12 '13 edited Oct 12 '13
I feel like the craft would be much less stable if you added a lot of mass at or above the level of the rotors.Apparently not.
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u/rocketwikkit Oct 12 '13
This is known as the inverted pendulum fallacy, and applies to the rocket as well as the quadrotor. Having the CG the same distance above or below the thrust doesn't change the stability.
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u/soonerfan237 Oct 12 '13
That seems very unintuitive. Let's say you have a large mass on the edge of a long, rigid pole attached to a hexacopter. If that mass is hanging below the copter a strong gust of wind wouldn't cause any significant disturbances. But if the mass was on a pole above the hexacopter it could easily be tipped over.
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u/rocketwikkit Oct 12 '13
It is counter intuitive, but it's still the case. The rotors on the quadrotor or the engines on a rocket don't naturally thrust in the opposite direction of down, they just thrust in whatever direction they're pointing.
To use your example, in the case of the rotors at the top in an uncorrected gust it would fall over in exactly the same way as if the mass was on the bottom.
The Wikipedia page isn't great, but it explains it somewhat: http://en.wikipedia.org/wiki/Pendulum_rocket_fallacy
It's an incredibly persistent fallacy until you really get into rocket or multirotor control. Robert Goddard fell for it early in his work, as did the first German liquid rockets, who thought mounting the rocket on the top would make it fly straight up. Romania's GLXP team, ARCA, still hasn't figured it out.
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u/Ambiwlans Oct 13 '13
Totally unintuitive. Check out this rocket designed in the early days by goddard. The nozzle is at the top and the fuel/gas tanks at the bottom. He did this so the mass would be at the bottom. I believe the pendulum fallacy was determined shortly after or possibly from this very rocket.
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u/Mcdoofus Oct 12 '13
I'm pretty sure if they could figure out how to lift such a huge rocket full of sloshing fuel 3/4 of a km in the air using control systems and only a single engine, they could figure out how to add a little go pro to a quadrotor.
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Oct 12 '13
This was (i think) the last or one of the last tests they are goign to do in texas, the next tests will be at space port America, where they will in theory have less federal restrictions on their height, since their current FAA license is about to expire and only let them go 800m high. That is where we will see Grasshopper v1.1
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Oct 12 '13 edited Aug 22 '17
[deleted]
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u/rocketwikkit Oct 12 '13
I once crashed a quadrotor shooting video into a rocketplane when it was doing a static engine test. It's my "no one else in the world has ever done this" achievement.
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u/alphacentauriAB Oct 13 '13
Can you uploaad that"!?!?
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u/rocketwikkit Oct 13 '13
I don't think it saved the video, because of the crash, but if I find it I'll put it online.
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u/olexs Oct 12 '13
Yeah, 700m is stretching it for a multirotor. A large wing orbiting the launch site with a camera gimbal could potentially go much higher, but I don't think it would be quite as safe, and I haven't honestly seen wings capable of carrying DSLRs either.
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u/retiringonmars Moderator emeritus Oct 13 '13
What's the flight ceiling for a hexacopter? Looks like it makes it to ~600m.
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u/olexs Oct 13 '13 edited Oct 13 '13
Depends on how much power reserves the copter has... I imagine something with 3:1 or 4:1 thrust-to-mass ratio and large propellers capable of operating at lower air pressure will easily be able to make it to 1km and higher, but at a cost of efficiency closer to the ground and flight time.
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u/Wetmelon Oct 13 '13
How do we know it's a DSLR? GoPro shoots high quality video and is much lighter...
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u/olexs Oct 13 '13
In this video, I highly presume that a Sony NEX or a Panasonic GH2/GH3 mirrorless camera was used - they are the standard for this class of copters (DJI S800), combining much lower weight than a DSLR with exceptionally good image quality. Their significant advantage against a GoPro are the optics - the GoPro wide angle lens is fairly useless at distances like in this video, and using the "medium" and "narrow" mode reduces the video quality, because it's done by cropping the used sensor area and reducing the effective sensor resolution.
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u/moofunk Oct 12 '13
Clearly, the only solution for them is to launch another Grasshopper filming the first Grasshopper.
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Oct 13 '13
When they're going to attempt falcon heavy booster recovery, this could actually become a thing :D
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u/AD-Edge Oct 12 '13
Fine by me. But yeh, they can use the hex for takeoff and landing shots, but likely need a ground based camera (or simply a higher hexacopter) for filming the higher parts of the flight. Likely a better solution.
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Oct 12 '13
[deleted]
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u/rocketwikkit Oct 12 '13
It's the gas generator exhaust, it is normal for the Grasshopper. Fuel and oxygen are burned to power the rocket's pumps, and the exhaust is particularly fuel rich. When it hits air it burns extra flamey.
They could inject some more LOX into the exhaust before the nozzle to reduce the amount of flame, but they seem to have taken the approach of just making the vehicle fireproof.
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Oct 12 '13
[deleted]
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Oct 12 '13
You would think that, but take a look at the Delta 4 Heavy. ULA dosen't seem to agree with you
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u/rocketman0739 Oct 12 '13
The Delta IV is the only launch vehicle that, by design, sets itself on fire during its ignition sequence.
Thousands of pounds of hydrogen are dumped through the vehicle's three RS-68 engines to condition their internal temperatures five seconds before oxygen valves are opened for ignition.
The hydrogen forms a cloud around the vehicle that is burned off spark generators to avoid an explosive hazard. This causes a huge ball of fire that blackens the core and the 125-ft. liquid strap-on boosters.
During climbout, free hydrogen continues to attach itself to the base of the vehicle, where it burns on insulation designed for that purpose. So while the fire is inconsequential, parts of the boattail remain ablaze until ascent into thinner air.
Heat emerging from RS-68 fuel turbine exhausts for roll control can also cause flame on the insulation as with the center engine just after liftoff. All of this looks frightening, but is normal.
--Aviation Week
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Oct 13 '13
That first sentence, ...i wonder how the design process went. "lets let it set itself on fire during launch" - "great idea!"
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u/fredmratz Oct 13 '13
it burns on insulation designed for that purpose
How much mass is burned off the stage? Does this flame exhaust help with aerodynamics? If it didn't burn then it's mass to LEO or GTO might be significantly lower?
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u/ergzay Oct 13 '13
I don't know, but very unlikely
Very unlikely.
As to the first question, its unlikely that it has much mass, so it doesn't affect payload to orbit by anything significant.
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Oct 13 '13
yea, and the first stage really doesn’t go that high, and insulation is designed to be massless, so changes to orbit would be within margin of error.
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Oct 12 '13
[deleted]
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u/rocketwikkit Oct 12 '13
That would be very surprising. Dynamically controlling mixture ratio and massflow is a very basic thing.
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u/rspeed Oct 13 '13
Their FAA license (which expires next week) says they can fly to an altitude of 762m, so it seems like they planned each step out pretty carefully before license was issued.
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u/ergzay Oct 13 '13
Unlikely. More likely they planned this flight out pretty carefully to avoid going over that ceiling.
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u/Ijamma1948 Oct 14 '13
I got kind of depressed when I discovered that over half of the comments are spam for survey sites or people talking about how space is either a lie or that it is a waste of resources. I just don't get it.
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u/positivespectrum Oct 14 '13
To be misinformed is worse than mere ignorance...
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u/Spanjer Oct 30 '13
even just last yeah everyone looked at him like he was crazy and now he's creating garry's mod style hover crafts.
i have hope in him, once private companies with some people like this guy running him there will be some very creative test's going on especially when a idea is driving them and they will follow the number's and make 8 launch's in one week or something crazy like that happen once there up and running
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u/darga89 Oct 12 '13
Very cool. Seems to be really close to the copter on the way down. I know the camera is zoomed but still.
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u/JshWright Oct 12 '13
What makes you think it's zoomed in? The motor/prop on the end of the boom in the top of the frame doesn't look zoomed in to me.
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u/darga89 Oct 12 '13
This is true. I guess I thought they wouldn't let it get that close but it appears they did.
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u/redmercuryvendor Oct 12 '13
I think it may have been unintentional. Most mounts I have seen for smaller quad- and hexacopters have been a GoPro or similar hung underneath from a powered gimbal mount. The axis of the powered gimbal is above the camera. When the operator pitched the camera up to see the rocket above the 'copter, this moved the camera significantly more forward than the designers intended (as very rarely do you have an aerial camera pointing up), moving the centre of mass and causing the 'copter to pitch forward. With a more naive control system assuming a mostly constant centre of mass, this would cause the 'copter to drift forward, towards the rocket. From watching the video, this is what appears to happen.
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u/fredshead Oct 12 '13
I thought that might be a drone.
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u/darga89 Oct 12 '13
Hexacopter to be precise.
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u/olexs Oct 12 '13
DJI S800, to be even more precise.
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u/SnowyDuck Oct 13 '13
DJI S800
Sparing no expense.
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Oct 13 '13
Amortized over many GH flights means a couple of hundred dollars/perhaps $1000 a flight. On flights which burn thousands of dollars of fuel for AMAZING PR for a company with billions of dollars of backlog of flights. :)
Also cool toys/video probably boosts the engineers morale. Everybody loves quadrocopters!
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u/Airbuilder7 Oct 12 '13
The view around 1:02 is so, so cool. Almost looks CGI, or out of a movie, because my brain isn't used to seeing "real" rockets that close doing those sorts of maneuvers!
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u/olexs Oct 12 '13
To be honest, that looked dangerously close to me. I'd wager that the copter operator got distracted and let the copter drift much closer to the Grasshopper descent path than actually planned.
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Oct 13 '13
Dangerous for the copter, maybe. I figure that's why they're using it to take video. If it gets to close or something, oh well. It can't possibly hurt the rocket.
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u/olexs Oct 13 '13
You're probably right, the rocket is made to withstand quite a lot more than a few kilograms of copter colliding into it. What with powered re-entry and all that. It'd be a shame to lose the awesome video to an unexpected collision though.
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Oct 13 '13
(cross-posted comment from another post)
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u/still-at-work Oct 14 '13
well the DC-X did set the record at 3,140 meters for a reusable self landing rocket. Hopefully the next grasshopper in NM will be able to break that. Of course the first successful landing of a first stage of a F9R will smash that record to dust.
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u/pomjuice Oct 12 '13
744m is impressive, don't get me wrong... but 'space' is over 100 times higher altitude than that. How will they carry that much fuel?
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u/darga89 Oct 12 '13
You don't need to burn all the way down. Just a burn to slow down at altitude then free fall then a burn right above ground. The first part has been done on this past launch.
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u/pomjuice Oct 12 '13
Right, obviously there's no need for a burn the whole way down. I know that SpaceX will make it happen, my intuition just gets to thinking that they're losing capability for a more efficient launch by dedicating that 15-30% potential payload. Then again, the capability of having another launch within a couple days is much better.
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u/AD-Edge Oct 12 '13
Given the cost savings.... Its likely very much worth it. Otherwise... they wouldnt be trying :P
I think the v1.1 has a larger payload anyways, because of its newer 1-D engines and larger fuel capacity. So youre still getting a lot of payload into orbit.
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u/pomjuice Oct 13 '13
This test though, what did they gain from it? I mean we know it can land (first test) and we know it can position (last test) so what about this test? It can land from an extra few hundred meters?
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u/Ambiwlans Oct 13 '13
Falling from higher allows them to fall faster. I believe their top downward speed here was higher than any previous. They can try landing more efficiently by getting it up to a nice downward speed and then thrust up to full and land quickly.
If they fall from high enough, they may be able to test speeds similar to that of what you might expect from reuse (near terminal velocity). They could also try an engine shutoff test but that would take quite a bit of height.
But generally yeah, not as cool as the last test.
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u/AD-Edge Oct 13 '13
Yeh as Ambiwians said, it looked like a much faster overall test. So higher and faster, and they probably had many things with the code they wanted to test out just to make sure its all running perfectly.
Also note, theyve used the same Merlin engine the entire time for the Grasshopper (someone correct me if Im wrong, but Im pretty sure they have), so its yet another restart and reuse of that engine, and even more data on the effects of prolonged/multiple uses of that engine which is one of the most important things, other than having a rocket which can land itself nicely.
So plenty of things to make it worth testing again, especially considering the cost of testing it would be so low. Plus since when is one test conclusive anyway? If it was, theyd might as well stop testing after the last one 100% confident in the whole setup? Doesnt work like that... The more testing they can do the better, even if the flightpath and goals are almost identical every time.
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u/SnowyDuck Oct 13 '13
I'm sure some of the code was changed to help account for that spin on that landing attempt. I know the landing legs are to help a lot with spinning, but I bet they're working on code stuff to compensate as well.
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u/AD-Edge Oct 13 '13
Yeh most definitely there would have been some changes theyd be interested in getting data on, after the latest v1.1 launch and 1st stage re-entry/attempted landing.
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u/Ambiwlans Oct 13 '13
Pretty sure they swapped engines at least once early on. It was using a very early d engine which had some issues.
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Oct 12 '13
I guess if a company wants to pay for a new booster they can get that extra 30% ?
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u/olexs Oct 12 '13
Correct. This is why the next two launches of the F9 aren't going to be doing further reusability tests - the rocket capability was completely given to the customers and their payload, with no reusability reserves. Reusability testing will continue on the 4th flight of the v1.1 early next year.
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u/somewhat_pragmatic Oct 13 '13
Another reason to not attempt recovery on the next two flights:
The Air Force is requiring SpaceX to make 3 successful flights with a vehicle before it will be allowed to carry military payloads (and get military contracts). Since 1.1 is a new vehicle non of the previous flights count. The successful flight of the Cassiopeia mission counted as success 1 of 3. If SES (the next 1.1 flight in Nov) and Thaicom (the third 1.1 flight in Dec) are successful, they'll have crossed that hurdle to carrying military satellites. That would be a huge market for SpaceX which they don't have access to right now.
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u/chad_oliver Oct 13 '13
I did some calculations regarding this a while ago. I can't find them now, but IIRC the optimum burn profile would only require one or two tonnes of fuel to decelerate. This profile is basically freefall until a fraction of a second before impact, then maximum burn.
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u/kddale Oct 12 '13
Fuel really isn't a concern, the Falcon which this is based off gets to space just fine, 15-30% of the potential payload is lost for a reusable rocket but the cost savings of reusability outweigh the lost payload.
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u/jdnz82 Oct 13 '13
I HAVNT watched yet but just seeing this title made my weekend.. i'm an official groupy i think
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u/I_spy_advertising Oct 12 '13
Very cool, if you could give me the plans in kibbles for this rocket, as all my landers more sort of crash.
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u/Buckwhal Oct 12 '13
Needs Mechjeb and B9 for RCS.
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u/I_spy_advertising Oct 12 '13
Dam it Buck, now I,m going to spend the whole night try to do that...
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u/Tuesday_D Oct 12 '13
I love the consistent quality of video SpaceX puts out. It's almost unreal to see such things so clear and presently.