back to article Leaping SpaceX GRASSHOPPER ROCKET jumps 2,500ft, lands safely

Elon Musk's Grasshooper vehicle has inched a little closer to becoming a viable VTVL (vertical takeoff, vertical landing) rocket, last week completing its highest flight to date. A video published by SpaceX on YouTube shows the ten-storey-tall jumper reaching 744 metres in altitude (a snip over 2,500 feet) before performing its …

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Sometimes you just gotta say "awesome" and stop there.

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Agreed - have an up-vote and I will say no more :)

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Flame

Awesome soundtrack

Just sayin'

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Thumb Up

Re: Awesome soundtrack

If you watch it with the sound off, I swear you can hear the Thunderbirds theme...

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Re: Awesome soundtrack

It's the flame licking back up the lower part of the rocket that makes me wonder whether Derek Meddings was prescient or had a way of looking into the future (he was a model making technological genius after all).

I always though 'it would never look like that' when I watched TB1 and TB2 land, but I was so obviously wrong!

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Re: Awesome soundtrack

I actually found it a little disconcerting the way the sound synced up with the action --- sound is *slow*, dammit, and takes a long time to get from the ground to the camera. I think that's one of the things that contributes to that wonderful air of unreality to the whole video.

I know why they did it, of course. I'm pretty sure the sound was recorded on the ground, otherwise mostly all you'd hear would be hexacopter drone. (At least, up until that scarily close fly-past.)

Do you think we could get them to rerecord it from a hot air balloon? They're quiet.

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This post has been deleted by its author

Did anyone else start watching this and think "wow that's a crappy CGI rocket, but at least the dust effect is pretty well done"?

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Anonymous Coward

The whole video is clearly CGI.

Look at how the horizon moves: perfectly smooth pan up, then as it reaches the bottom of the screen there's an instantaneous stop, zero judder, absolutely motionless. You couldn't even do that from a static tower.

Then look at the trajectory of the rocket: absolutely perfectly vertical, not the slightest flicker of deviation and correction.

The rotor blades are just a superimposed distractor. The cigarette-lighter flame effect was an odd choice.

Are SpaceX really trying to claim this is genuine footage?

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Are you taking the piss? Its real I'm afraid.

This is real stuff - there was a photo posted on Twitter taken by someone off site (ie not SpaceX) of this flight.

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Joke

"The whole video is clearly CGI."

And when the rocket touches down, it's not touching its shadow and the shadow has to keep on moving for a second.

Obligatory XKCD reference [331].

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HMB

@Brewster's AG

An up vote wasn't enough. I was properly laughing out loud, cheers for the XKCD, very appropriate.

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Too damn cool

Congrats again to Space X for another successful milestone.

If I didn't know that was real, I would have sworn I was watching some very cool CG.

Too bad the DC-X project was abandoned years ago. We could have already had this technology.

Good for Space X to pick this up and continue its development. I sincerely wish them godspeed and good luck.

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*scratching head*

I clearly know nothing about rocket science math, but I keep wondering how exactly that "powered descent after launch" is supposed to work, given that a launcher is supposed to boost its cargo to some seriously high speeds and heights? How much "reserved" fuel does one need to do a controlled descent from that height / speed...? Or is this going to come back down the standard way (a parachute), jettisoning it and powering up just before it touched back down...?

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Happy

Re: *scratching head*

I think there's some nominative determinism at work in your comment. (It's a good question too.)

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Boffin

Re: *scratching head*

The plan is for the firs stage to separate at Mach 6 and coast up till the air is very thin. It then does an end flip and fires 3 of its 9 engines. This has already been tried in the 1st V1.1 launch. This cancels its forward speed and (I think) gives it a bit of momentum so it "falls" back to the landing site. It's then flipped backwards so it will land engines down.

The powered bit only starts up in (maybe) the last 1/2 mile of descent. So far it appears to be a "bang bang" approach. A short sharp 3g burst of thrust that kills momentum leaving a short fall onto the landing pad cushioned by its legs.

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Re: *scratching head*

with no organic meatbags to worry about it can be pretty sharp on the acceleration too.

If it goes wrong you might have a big fireball at the launch site.

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Re: *scratching head*

It's also a lot lighter when it comes down, so it doesn't need a comparable amount of fuel to stop as it needed for going up the hill...

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Re: *scratching head*

The boosters that are being trialled here don't push the satellite all the way into orbit. They are the first stage boosters only and detach shortly after launch (like the boosters on the space shuttle). As they are travelling 'relatively' slow (but still a few machs!) they get slowed down by air resistance as they fall to earth and land and are recovered.

The main booster that takes the rest of the satellite all the way to orbit will still be use-once disposable rockets.

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Re: *scratching head*

This is the proposed launch sequence.

http://www.youtube.com/watch?v=sSF81yjVbJE

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Re: *scratching head*

It's been a while since I saw information about this. There is some debate but as I recall the estimate is from 10% to 30% of the fuel. The key thing is that the returning rocket is not longer carrying the weight of the second (& following) stages, most of the fuel is gone, and a big part of the fuel was spent achieving maximum velocity. That velocity can be given away by merely letting gravity take over, only maintaining the proper vertical attitude**, until the thing is coming back at a suitable rate - in fact I think it's best to wait to decelerate (perhaps just maintaining some maximum descent speed?) until the last minute* and use the remaining fuel all at once IIRC. So, taking all that into account, the fuel required to bring it back is much less.

* the last minute - gravity is always accelerating the vehicle downwards. If you slow it down too soon, you'll have to keep burning fuel for a longer time.

** some reusable vehicle designs have been based on a 'flyable' first stage that would use minimal fuel to return, and land on a runway. But that has its own price in weight.

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Alien

Re: *scratching head*

The numbers seem about right. The higher you go the more fuel you will need for return though so you do have to spend more on that but it is no problem as it is not the main cost factor. There will have to be multiple burns on descent to keep the thing relatively cool and possibly stable but should not be too many. In theory you could haul ass down an then do a crazy -x*g burn just before touch down but you would need an engine that produces huge trust on demand, not an optimal solution as u use the same engine to go up.

Keep in mind that this is all just a beginning, mostly touch down tests that have been done many times before, relatively proven stuff. Once you start dealing with the low orbit re-entry, the flip in the atmosphere, things will get rough and lot of unpredictable events can happen. The success I believe largely depends on the proper timing and very good control systems. Structural dynamics will also play important role because some of the maneuvers at such high speed will create huge amounts of stress on some parts.

It is a good start though, that is for sure. Keep it up.

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Re: *scratching head*

The last Falcon 9 launch did some first stage tests to check out exactly this. (The first stage started to spin longitudinally, which centrifuged the fuel away from the inlets at the bottom of the tanks, and the engines went out. They're working on it.)

It's also worth pointing out that:

(a) the F9 first stage carries extra fuel *anyway*, in order to compensate if an engine dies on launch --- this happened on a previous flight. So a landable first stage doesn't need more fuel. It just lands on the safety margin left in the tank. If you end up using this safety margin in launch then you don't get to recover the first stage. No big deal.

(b) falling through air soaks up an enormous amount of velocity. Instead of having to decelerate from 7000 km/h at mach 6, you let the air do it for you; when you get close to the ground you're only moving at a few hundred km/h. This saves an incredible amount of fuel.

Regarding (b), go get the eval copy of Kerbal Space Program and try it out for yourself.

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Re: *scratching head*

They tried reigniting the second stage as well, but stopped due to a problem.

They're looking at recovering both stages.

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re. the observing video camera

I just watched the video (I had to disable AdBlock .....shudders). Is that one of the arms of a quadracopter, or similar remote controlled device, that you can see towards the peak of the climb? I suppose it would be cheaper than using a helicopter.

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Re: re. the observing video camera

Yes it is. You can see two of the rotors at one point.

Guessing hexaopter, but harder to tell

It's the only sane way to get this kind of footage - no helicopter pilot is ever going to agree to fly that close to an operating rocket!

I think some of the apparent CG-ness comes because the camera gimbal is too good!

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Holmes

Re: re. the observing video camera

It is a hexacopter. Clue is in the title of the youtube vid.......

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Anonymous Coward

Re: re. the observing video camera

> I just watched the video (I had to disable AdBlock .....shudders).

I use AdBlock too, but it doesn't block TheyTube by default. It just adds a little "Block" tab next to the Flash object, should I want to block that content (it does block Flash ads, btw). I don't recall modifying the default configuration, btw.

> I suppose it would be cheaper than using a helicopter.

And safer!

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Re: re. the observing video camera

Richard 12 wrote:

"I think some of the apparent CG-ness comes because the camera gimbal is too good!"
I'm fairly certain the footage has also been additionally stabilised after shooting. A clue is the way the horizon seems almost locked in place yet one of the hexacopters rotors drops into view then goes back out of frame... Thats either post stabilised footage or one bendy rotor arm! Further still, when the camera tilts up, past the horizon, and the rotor comes completely into view the rocket then almost seems locked into place while the rotor is all over the shop, again a classic sign of post stabilised footage.

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Happy

Re: re. the observing video camera

It's the only sane way to get this kind of footage - no helicopter pilot is ever going to agree to fly that close to an operating rocket!

Well they should just man up! What a bunch of big-girls'-blouses!

There's always the tactic used when they made 'The Battle of Britain'. They had a B17 as their main camera plane, because it was about the same speed as the fighters, and had lots of places to stick cameras.

But obviously too dangerous for shots of fighters coming at the camera head-on, or the really close dog-fighting stuff. So their solution was to get a helicopter, and rig a cradle on a 300 foot wire. Then their looniest cameraman sat in that, with a camera rigged on some kind of gimbal mounting and let planes fly almost straight at him. Balls of steel. Not sure what it says for his brains though...

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Re: re. the observing video camera

For this kind of shoot, you generally mount the camera on its own stabilised gimbal.

This is the only way to ensure the camera stays pointed in the chosen direction while the 'copter moves around to manoeuvre and stabilise the overall frame.

A two axis, tilt and roll gimbal covers the stabilisation motions a 'copter will do, then pan by rotating the whole airframe.

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Can someone explain...

..why SpaceX did not get the "most innovative company" award?

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Yag

Re: Can someone explain...

Because they're not innovative enough where it counts (according to the jury) : PR, marketing and fiscal avoidance.

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Re: Can someone explain...

HA! I made the same comment to that article as well!

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Re: Can someone explain...

it is primarily based off Mcdonnell D DC-X though and since that had a contract to scaled composites they are simply reexamining work done by a bigger team. Sure they are making it work better but not innovating (it is fantastic work nontheless)

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Re: Can someone explain...

"it is primarily based off Mcdonnell D DC-X though and since that had a contract to scaled composites they are simply reexamining work done by a bigger team. Sure they are making it work better but not innovating (it is fantastic work nontheless)"

Wrong.

Blue Origin (or rather what little they release) is doing some work based on the DC-X.

DC-x sidesteps the control problems by using a wide/squat lifting capsule shape. This is much simpler to control and make (relatively) rigid. OTOH normal rocket stages have high aspect ratios and are "floppy." The control problem has AFAIK never been thoroughly worked out, which is what they are doing.

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Well it works in Kerbal Space Program.

What took them so long?

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Clearly...

Clearly they used mechjeb. Cheats!

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Re: Mechjeb

Mechjeb isn't cheating!

It just makes things slightly easier....

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Re: Well it works in Kerbal Space Program.

It looked a lot like they used KSP to create that footage.

jk Great job again Space-X!

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Nya

FAB!

They have to paint one up to look like Thunderbird 1.

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Re: FAB!

Damn! That's genius! (seriously. wished I thought of that)

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Mushroom

Re: FAB!

Or TB3. I (think I) remember seeing TB3 return to base. Alan has to get the craft back through the opening in the torus-shaped building. At least Scott had a swimming pool he could dump on the flaming wreckage should he get the landing wrong.

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Re: FAB!

If you remember, the swimming pool moved under the patio when TB1 took off or landed, so he did not have that option.

The torus shaped building was called 'the roundhouse'. Quite what you use such an unusually shaped building for, I don't know.

I'm sure that the few times they show the clip of TB3 landing, they've even managed to collect the smoke again. That's really environmentally aware!

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Re: FAB!

"The torus shaped building was called 'the roundhouse'. Quite what you use such an unusually shaped building for, I don't know."

The Fusion Reactor (probably).

Perhaps Musk's eggheads can get to work on that unsolved problem after completing the full set of TB craft.

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Anonymous Coward

That cameraman ...

.. should be shot.

Otherwise, yes .. Awesome!

That noise!!!!

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Re: That cameraman ...

You do realise that the cameraman was one the ground controlling a remote hexacopter? Seems to me that he did a pretty good job.

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extra flame

What is the extra, non-thrusting, flame coming out of the side?

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Re: extra flame

Think it's part of the control system - presumably it's adjusting position by dropping power to certain parts of the rocket engine, and those flames are the excess fuel being dumped and burned in a non-power generating method?

That's what I've assumed, anyway - anyone know any better? As noted above, they don't seem to be especially powerful (compared to the main engines) so just dumping fuel before it hits the main engine units to 'dial them back' and allow attitude control?

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Re: extra flame

No, it's the exhaust from the turbopump I believe. Quite a flamy one!

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