Reuse the Force, Luke: SpaceX's Elon Musk reveals X-WING designs SpaceX boss Elon Musk has been showing off steerable wings on his company's Falcon rocket booster – and a floating landing pad to catch the reusable craft out at sea. Musk revealed the tech in a series of tweets over the weekend. He said future builds of the Falcon rocket system would carry stabilizing tabs – dubbed "X-wings …
" It remains to be seen if a top-heavy rocket booster can successfully land and be safely secured in heavy seas."
Mr. Thomson, wouldn't the Falcon 9 rockets be extremely bottom-heavy? The only thing on their top (after second stage separation) are lightweight, empty fuel tanks. On the other hand, there will be 9 dense rocket motors, 4 landing legs, and now 4 steering fins at the bottom, and any residual propellants will also be in the bottoms of the tanks.
I mean, it kind of seems like the center of gravity would be similar to a hammer standing on its head: very near the bottom. The light body would be an annoying sail in high cross-winds, but balance shouldn't be an issue unless I'm misunderstanding the weight distribution in the Falcon 9.
I am guessing that there are quite a few kg fuel still in the tank, presumably near the bottom.
NASA did sums years ago that said that the cost of the fuel carried in order to effect a soft landing is far greater than the cost of manufacturing more rockets and high pressure pumps is too high - given that rocket motors beat the crap out of themselves and are not ideal for prolonged use. Mr Musk must have a cheaper fuel system and more robust motors.
The cost of the LOX and RP-1 used in the launch is noise compared with the cost of the hardware. I think the figure of $200K was stated, a Falcon 9 launch is in the order of $54M. The 'cost' is the lost of performance involved of keeping some back for the the boost back and landing. This means that the 2nd stage will need to do more work, so some lost of payload.
The Merlin engines will have been designed with reuse in mind with greater margins, specially in the turbopump area.
"The 'cost' is the lost of performance involved of keeping some back for the the boost back and landing. This means that the 2nd stage will need to do more work, so some lost of payload."
Or plan B: make the first stage bigger to carry more fuel. ;)
The v1.1 of the Falcon 9 is 505 tons on the pad, versus 333 for v1.0. It also stretched by a third (68m tall vs 54) on the same diameter. To handle the fatter rocket, the Merlin engines grew ~20% in thrust between the 1C and 1D models, while their "mileage" increased by 7 seconds of specific impulse.
Supposedly, the Falcon 9 v1.1's 13 tons of payload to low orbit (vs 10 tons on the v1.0) does not include a 30% margin reserved for landing fuel. So, the Falcon 9 not only stretched to handle first stage landing fuel requirements, but also gained 30% more payload.
"NASA did sums years ago that said that the cost of the fuel carried in order to effect a soft landing is far greater than the cost of manufacturing more rockets and high pressure pumps"
It's not the fuel directly - fuel itself is a small part of rocket operating costs, especially in expendables. The problem is all the parts that handle the fuel (tanks, pumps, valves) stop being single use. The short cuts you can take with single-use, short-lived hardware are interesting, be they computer chips or rocket motor housings. For example, compare the cooling system of a well-made desktop computer to a short-ranged missile guidance system: one needs a small block of aluminum to soak heat for 5 minutes (after which no one cares about the chip because some nearby energetic material went high order) while the other needs a much-larger assemblage of heat pipes, copper fins, water pumps, fans, and/or radiators that should last for thousands of hours.
"given that rocket motors beat the crap out of themselves and are not ideal for prolonged use. Mr Musk must have a cheaper fuel system and more robust motors."
Rocket motors aren't ideal for prolonged use, but there's always shades of reusability. The expendable F-1 engine of the Saturn V was tested and reused in ground tests and experiments (such as dropping them in water for engine recovery testing for the potential Saturn ID stage), and was fairly modest in its maintenance requirements between engine firings. As I recall, soot accumulation in the turbopump and nozzle cooling passages was one of the larger issues. On the other hand, the Shuttle's SSME was meant to be reusable, but was 1) very high-strung and thus had limited margins - it was barely tough enough to endure the beating it gave itself, and 2) the parts that needed a lot of attention were difficult to inspect (requiring borescope inspections) and hard to open for repair.
If you don't mind taking some percentage off efficiency and adding a few pounds here and there for more robust, easily-dismounted components, liquid fuel rocket motors can be fairly reusable. And even if you only get 4 or 5 extra uses out of an engine and maintenance proves to be 90% as expensive as building a new motor...well, you're still saving money.
What's interesting to me is that SpaceX's Merlin engines are not just reusable to some degree, but very light. They've set records for thrust-to-weight ratios. I'd like to learn more about the techniques behind them.
This contraption is in the video clearly frightening the cattle, I am sure it will also sufficiently frighten farm fowl that they will cease to lay. What will happen to our breakfasts with all farm beasts terrified and what about our terrorised children?
This foul smoking machine of the Devil will come to no good! Mark my words!
Signed Colonel Sir Nimby Upping-Twatberry (Mrs) ( Major RTD)
On a slightly more normal note, the date on the video was June, Haven't we seen this before?
Musky could afford to buy (or build) his own island or volcano to land the boosters in/on, would be a lot better than trying to land on a tarted up oil rig.
I have to say I'm quite surprised they didn't go with a SWATH ship - its whole point is that it is as immune to rough seas as one can possibly get in the 21st century - and the layout seems to naturally fit the requirement for a wide, flat vessel (well, maybe they aren't watching as much Discovery Channel as they should)... Paris, 'cos we are just about on the same level of expertise on this stuff.
Remember that this is being done with private funding, not Government OPM. retrofitting a barge is a lot cheaper than building a whole new boat and cutting a SWATH through the bank account. Still, it is impressive what a couple of billion will buy these days compared to what you got in 1969.
"I have to say I'm quite surprised they didn't go with a SWATH ship - its whole point is that it is as immune to rough seas as one can possibly get in the 21st century - and the layout seems to naturally fit the requirement for a wide, flat vessel"
True. You could custom-build a very stable SWATH. But I'm guessing this is just a stopgap until he can prove he can do it safely and then move recovery operations onto land.
Consequently I very much doubt that barge was built for SpaceX - it's probably just a second-hand commercial barge that they bolted some hefty station-keeping gear on and a big landing deck.
"This contraption is in the video clearly frightening the cattle"
Yes, they do seem to be running away in fear during the launch. On the other hand, they all seem to running for a closer look at the landing. Maybe they are realy interested in the outcome of these tests. They do have a vested interest after all. It's long time since a cow jumped over the moon.
A superlative idea, sir, with only two minor flaws:
1. We have no idea what kind of material could support its own weight over a length of tens of thousands of kilometres; and
2. We have no idea what kind of material could support its own weight over a length of tens of thousands of kilometres.
Now, I realise that, technically speaking, that's only one flaw. But it's such a big flaw, I thought I ought to mention it twice.
© Red Dwarf
"2. We have no idea what kind of material could support its own weight over a length of tens of thousands of kilometres."
3: Even if it existed, we have no practical way of getting enough of it into place to drop down.
No, Falcon XX heavy isn't nearly large enough for a 70,000 mile long ball of string.
From the launch video, any sort of launch failure could lead to an impromptu BBQ.
I would not bet against Elon Musk. The guy seems to be a winner. The reusable rockets scenario has high promise. If he can't get commercial cargos for the reused rockets it looks like he can launch his own Skynet.
As is typical of articles like this the author did not understand what he was reporting on. The platform as per the information released by Elon Musk was that he platform was 300 x 170 feet. The platform was 100 feet wide with 70 feet of extensions making it 170 ft. The rocket on decent is bottom heavy as stated above but the fins are at the top of the first stage not the bottom. There are two good examples of this. One if the photo of the Falcon 9 1.1 on its side posted this weekend showing the fins. The part of the rocket to the right of the clamp around it is the faring that fits the Dragon with the Solar Arrays folded and covered. The other is the video of the 1000 ft flight of the F9R 1.1 at McGregor, Texas. It is clear that the fins are at the top of the First stage here also.
Pretty sure I've seen these grid type affairs on smaller missiles (IE smaller than a cruise missile size) because they give more control for the same surface area, require less torque to turn, and other such reasons.
Edit: I probably recognise them from the MOAB - AKA the bomb you don't want dropped on you any time soon. Dunno about smaller things, maybe my imagination?
Looks cool in action though, dunnit?
Everything having to do with space is a harsh mistress. The Moon, John Clark's rocket fuels, etc.
To quote yet another author: "Rocket science is a harsh mistress. Please her and she'll send you blasting off to amazing new worlds, but screw up in the slightest and she'll slam your balls in a car door so hard they explode in flaming pieces across five states."
...if, and it's a big if...
Gadzooks, sir! Seeing as how SpaceX has Landed a rocket from space before (on water, true, but still, landed), I'd say it's a much smaller 'if' than, say, in 2010.
Surely they're at least at the 'probably going to work' stage now.
"Gadzooks, sir! Seeing as how SpaceX has Landed a rocket from space before (on water, true, but still, landed), I'd say it's a much smaller 'if' than, say, in 2010."
Pshaw. Landing a rocket stage in water is easy, the US has been doing it for decades. Intact landings, though, are a rather smaller subset of the practice. ;)
Those were water landings? I thought they were drone strikes (and before there were drones no less!) against evil, terrorist fish! It certainly explains why we haven't heard of... Salmon Bin Leapin...
Hey, the icon says 'joke', it doesn't say good joke...
When I was but a wee lad...
~~~ wavy lines as we cut to a scene in the distant past ~~~
I was fortunate enough to have a look around HMS Liverpool, a big navy ship with a helicopter deck at the back. I remember there was a grid of holes in the central area of the helicopter deck so I asked one of the crew what the holes were for. I was told that the helicopters were fitted with a downward-pointing spike thingy which would grab the holes as the helicopter landed so that the helicopter was held down and couldn't get bounced off if the sea was rough.
~~~ wavy lines as we return to the present ~~~
Would SpaceX's Falcon benefit from using such a system to anchor it onto the floating landing pad?
EDIT: here is a description of the sort of thing I mean: clickety
Size matters, size matters.
I suggest the author of the article takes the Stena Superferry between the hook of Holland and Harwich. I have done the crossing in a level 6 storm and you could not feel a thing. If the landing barge is big enough it should indeed be OK for a reasonable storm (I would not try to land on it in a tropical hurricane). It also depends where you land. The beauty of sea launch and recovery is that you can do it anywhere. While the Indian and Pacific oceans always have a sizeable wave, the Atlantic puddle quite often calms down to a nearly-lake state (especially in the tropics).
As far as wings... these are not wings, these are aerodynamic control paddles same as on the ESA reusable "spaceplane" project. Nice design - should allow the rocket to use less fuel during the return phase.
Re-usable rocketry and marine landings my arse.
Look at that boat deck - Elon Musk is clearly attempting to get a head start in the soon-to-be-announced interplanetary darts championship, while those steerable wings look suspiciously like orbital ping pong paddles to me...
How will it avoid getting hit by orbiting space junk? Long story short, it won't. So there'll have to be enough redundancy/toughness in the building material to survive that. That said, there won't be that much junk on an orbit that intersects with the elevator.
A lot in total, yes but not that much in the fairly small volume, as compared to all of Earth's orbital volume, will be prone to bumping into the elevator.
One thing they've discussed for space junk is lasers. Not big blast-em lasers to vapourise them but just to heat them up and so 'nudge' them into raising/lowering their apogee/perigee so as to shorten their orbital life. If you can do that, then surely you can use lasers (small ones, remember) to prod the junk into (or away from) certain orbits so as to diminish the frequency of likely meetings.
Just wait, soon a newsreader will be calling them 'orbital oopsies'....
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