SpaceX Landing Attempt Video Released 248
An anonymous reader writes: Last week, SpaceX attempted to land a Falcon 9 rocket on an autonomous ocean platform after successfully launching supplies to the ISS. It didn't work, but Elon Musk said they were close. Now, an amazing video has been recovered from an onboard camera, and it shows just how close it was. You can see the rocket hitting the platform while descending at an angle, then breaking up. Musk said a few days ago that not only do they know what the problem was, but they've already solved it. The rocket's guiding fins require hydraulic fluid to operate. They had enough fluid to operate for 4 minutes, but ran out just prior to landing. Their next launch already carries 50% more hydraulic fluid, so it shouldn't be an issue next time.
Wait a minute (Score:5, Insightful)
It suddenly occurred to me that I've never heard of a hydraulic system "using up" its fluid before. Anyone know anything about how/why the rocket is different?
Re:Wait a minute (Score:4, Informative)
Maybe they save weight by not providing a return line?
Re: (Score:2)
Maybe they were using it as fuel.
Something isn't adding up here, but it wouldn't have surprised me of the obfuscation filter otherwise known as the media has garbled the message.
Re: (Score:3, Interesting)
Others are posting about an open system. Besides the loss of the hydraulic fluid which would lighten the load you should also consider that to make a closed loop system it would add mass in the parts and tubes which would be required to contain and create the closed loop.
Re:Wait a minute (Score:5, Informative)
And pumps and motors.
All they need is a pressure tank.
Re: (Score:2)
but that means you have to carry more fluid. Unless there's very little fluid normally needed, I don't see how ditching the pumps and motors saved enough weight to put enough additional fluid in the reservoir to matter. I see two lines on a weight graph, a horizontal one for the closed-loop, and a curved line representing the open-loop. At some point these lines cross, and the open-loop becomes a worse option. I'm just surprised that point isn't way earlier for them.
Re: (Score:3)
An open system is also a whole lot simpler. Weight is very important, but so is reliability. If a pump fails (keep in mind the extreme environment), you lose the stage. Increasing the reservoir size is much simpler and more reliable.
Re: (Score:3)
They landed on the barge is the thing. And not badly either - you can see it come down, and then fall over due to skew angle. The fact it landed anywhere even near the barge is damn amazing.
Re: (Score:3)
Yep. From 1300 meters per second to maybe 3 meters per second, with a CEP that would make military ballistics engineers salivate. So, so close.
Re: (Score:3)
The booster already had 2 hydraulic systems when they discovered that they needed fins to stabilise the booster on descent. RP-1 is used for the engine actuators at the bottom of the booster and a separate open hydraulic system was used at the top using pressurised Nitrogen to assist in Stage separation. The RP-1 hydraulics are active when the engines are active but the fins are needed throughout descent (when the motor is off most of the time) so the upper hydraulic system is used.
Re:Wait a minute (Score:4, Interesting)
It's an open loop system, presumably to save mass.
Re:Wait a minute (Score:5, Informative)
@alankerlin Hydraulics are usually closed, but that adds mass vs short acting open systems. F9 fins only work for 4 mins. We were ~10% off.
Better quit from Musk (Score:5, Informative)
he tweeted [twitter.com]
Next rocket landing on drone ship in 2 to 3 weeks w way more hydraulic fluid. At least it shd explode for a diff reason.
Re:Better quit from Musk (Score:5, Funny)
At least it shd explode for a diff reason.
Too much hydraulic fluid?
Re: (Score:2)
Just like water in nuclear reactors, you can't have too much hydraulic fluid in a rocket landing.
Re: (Score:3, Interesting)
I wonder if they are using a pressurized accumulator for the fins instead of a pump. Still a bit odd since the air flow that close to landing should have been next to zero and one would assume that they still had thrust vectoring on the main engine.
Re: (Score:2)
Maybe the main-engine vectoring used hydraulic actuators? Internal verniers, nozzle steering, engine steering... something has to push it around, and why would you have two actuation systems? If you're too mass-cheap for a closed-loop hydraulics, a complete independent actuator system for thrust steering seems like a bad bargain.
Re: (Score:3)
I see later down in this discussion that the engine steering is done with pressurized fuel, which is presumably then dumped into the exhaust stream to burn. And the other actuators are too far from there to make it practical to extend the fuel-based hydraulic system to them.
Weird set of engineering compromises, but they make sense. Too bad about underestimating the capacity needed for the upper hydraulic reserve.
Re: (Score:3)
Using fuel for hydraulics is standard practice for rocket and jet engines. It is really a given. Using a pressurized total loss hydraulic system for the fins is... an interesting system.
Re: (Score:3)
Boosters don't need hydraulics just for the engines, they are also needed to assist in stage separation -- at the opposite side of the booster and at a moment when the engines are off & the RP-1 system is no longer actively being pressurised so they almost always use a separate system using a pressurised tank of fluid. When the need for a hydraulic system for fin actuators on descent was discovered (again, when the engine is mostly off & at the opposite side of the booster) it was logical to use it.
Fins went hard-over when the system ran dry. (Score:4, Interesting)
Elon stated while being questioned last week that the steering fins went hard-over (which means they were driven to their maximum angle) when the fluid ran out. With the fins pushing the rocket over, it didn't have much hope of landing. And, yes, a pressurized accumulator is the most likely design of this system.
/u/DixieAlpha over at reddit programmed a Kerbal Space Program model to try to land with grid fins fixed at 30 degrees. The results were scarily similar to this landing. [reddit.com]
Re:Wait a minute (Score:5, Insightful)
Less complexity, less weight (and gets lighter as you use it). No pumps, no power source for pumps, no return lines, just a pressurized tank and a few valves.
Of course, you have to know how much you'll need before the flight, and the longer you'll need it the lesser the savings over a traditional system.
Re:Wait a minute (Score:5, Funny)
"Elon, I TOLD you we should have pulled over and bought more fluid at the last stop!"
Re: (Score:3)
Extremely funny, but I bet, that small modification might happen that won't increase the weight issue too much. Lot's of nifty ideas floating around here.
Re: (Score:3)
A new dimension for "range anxiety".
Re: (Score:2, Informative)
It is lighter and more simple to use up (to expel it when it has done its work) any hydraulic fluid than it is to have a scavenger system. While this would be a problem on your car if each time you pushed the break cylinders it squirt out the fluid after it had actuated the break on a rocket it saves on over all weight and complexity just to have "enough" fluid to do the job
Re:Wait a minute (Score:5, Informative)
In a normal hydraulic system there is a pump that re-pressurizes and returns the hydraulic fluid to a reservoir. To save weight and complexity here since the hydraulics are only used for a few minutes they instead use an "open" hydraulic system in which the pressure comes from a tank of compressed gas and the hydraulic fluid is expelled or burned up as it is used. (The fluid goes one way - out - as it is used).
After the pressurized gas or fluid was used up they no longer had control over the fins.
Re: (Score:3)
Everyone is assuming that the spent fluid is being dumped overboard. Do we know that to be the case?
It's only necessary to expel the spent fluid externally if you want to reduce overall rocket mass while doing so. If that's not necessary, you can still use an open loop system but have a recovery tank to receive the spent fluid, thereby preventing environmental contamination. That's really the only reason to contain it; the cost of lost spent fluid is probably minimal.
Re:Wait a minute (Score:4, Informative)
The main hydraulic system on the F9 (for gimbaling the engine nozzles) uses RP-1 (i.e. rocket fuel) as its hydraulic fluid. Spent fluid from that system goes into the fuel tank.
The fins are driven by a separate system at the top of the stage, if they pumped the spent RP-1 overboard you'd have flammable liquids running down the stage, I'm pretty sure they don't want to do that. Returning the RP-1 to the fuel tank is unlikely (needs an insulated pipe around the outside, next to the cold LOX tank). So probably a separate waste tank near the fins.
Re: (Score:2)
I was about to ask the same, a bit more poorly worded perhaps :D
Re: (Score:2)
So what happens to the fluid?
Re: (Score:2)
So what happens to the fluid?
Presumably, it just gets dumped out of the rocket somewhere.
Re: (Score:2)
Re:Wait a minute (Score:5, Insightful)
Re:Wait a minute (Score:4, Funny)
It is poured on dolphins.
Re: (Score:2)
Re:Wait a minute (Score:4, Informative)
The first stage of a rocket is never going to Mars, or even to orbit. They may need something different on a third stage of a Mars rocket, but that's no reason not to keep the first stage simple.
Why use hydraulic fluid? (Score:2)
Seems to me that I would save that for emergencies. Use the high speed descent to pressurize air for controlling.
Just saying...
Re: (Score:2)
I would assume for the same reason they are using an open system rather than a closed system: to save weight and complexity.
Also, I'm not a space nutter, but this stuff impresses the hell out of me. That looked damn close.
Re: (Score:2)
So, instead of taking a larger reservoir of hydraulic fluid you recommend they install a secondary pneumatic control system as well, along with an efficiency leeching ramscoop for collecting compressed air? Sounds like a good way to simultaneously increase complexity and reduce payload to me.
Re: (Score:2)
Seems to me that I would save that for emergencies. Use the high speed descent to pressurize air for controlling.
Just saying...
Due to the fact that they've only got 4 mins of fluid, I'd say they're already doing that. It's for the low-speed descent to the capture pad that the fluid is needed. Obviously, they cut their margins a bit too close, and so now will be increasing the fluid instead of decreasing the control time. I'm sure they've run the numbers to see if the other way was more viable, as they want as little extra mass as possible.
Re:Why use hydraulic fluid? (Score:5, Informative)
Seems to me that I would save that for emergencies. Use the high speed descent to pressurize air for controlling.
While IANARE, The problem with pressurized air as a control mechanism is that it is elastic/compressible (while hydraulic fluid is basically non-elastic/non-compressible). Which means that if you use air your control is basically going to suck big donkey's balls as your control vanes will bounce around in the airstream as the air in the control system acts like a big spring. Thus degrading the landing accuracy of your rocket.
On the other hand hydraulic fluid being stiff means that when you send the control vane to a position it stays there, and the only thing that moves it is a leak or destruction of the vane. Note that they will be some bounce in a hydraulic system, but nowhere near as much as in an air based system.
Now as to the hydraulic fluid in this case being used up, I am guessing that they considered the mass imposed by a collection system and decided, "fuck it, it's too much mass to recycle it, we're just going to dump that shit overboard".
Re: (Score:3)
Don't tell us, tell them!
http://www.spacex.com/careers/... [spacex.com]
Re: (Score:2)
Curiously familiar (Score:5, Funny)
Looks like most of my Kerbal Space Program landings.
Re:Curiously familiar (Score:4, Insightful)
Based on my experience in Kerbal, they're 95% of where they need to be. They've done the really hard stuff (controlled burns to bring the craft down at the right spot, slowing the descent at the right time without running out of fuel, etc) successfully. Properly orienting the rocket should be relatively easy assuming that the systems responsible for that haven't run out of fuel. The fact that the engine was able to get it that close without the fins working speaks volumes for how well the thing is operating.
Even if something else goes wrong the next time or two, they'll have a successful landing shortly. The simple fact that it hit the platform ought to be enough to let them start trying on land after another one or two similar attempts. As failures go, this was extremely successful.
Re: (Score:2)
Then your complex part is terrestrial, where it's not offsetting potential payload and easier to maintain.
I know i
Re:Curiously familiar (Score:5, Insightful)
Firstly, it was considerably easier to do it on the moon. Low orbital speed, 1/6 the gravity, no air resistance on descent, very light lander (as it wasn't pushing 40+tons of second stage to orbit).
Secondly, this stage was doing Mach 8 to 10 at about 80km altitude when it separated from the second stage. They did an extra burn that briefly popped it out of the atmosphere, reversed its course, then did a hypersonic re-entry tail first and (nearly) landed on a 50x60m barge.
Nobody has done that before. Not the guys with the shuttle SRB's, they just fell back to earth (and were strong enough to withstand the tumbling in the atmosphere, being SRBs). Not Boeing with it's dinky little hops of 10,000 feet in a continuously-stable attitude at subsonic speeds. Nobody has gotten this far before with the return of the first stage of a liquid-fuelled booster. Seeing as those things are enormously complex and very expensive, it'd be great to get one back in one piece to use again.
Re: (Score:2)
This test was a successful failure (Score:5, Informative)
This was the first time SpaceX had flown the new grid fin control system on a real first stage under real conditions. They did not know exactly how well the grid fins would behave. As it turned out, the grid fins had to move more than they expected during the descent (or the forces were larger than they expected), so they ran out of hydraulic fluid 30 seconds before landing. This is similar to an airplane losing control of its elevator just before landing. The fact that the rocket reached the barge and that its vertical speed was reasonably slow (certainly not 100m/s) indicates the resiliency of their systems. They are putting 50% more fluid into the system, so this shouldn't happen next time.
I think this video is epically cool. I can watch it again and again. Simply awesome.
Re: (Score:2)
Indeed. I'm not a space nutter, but this impresses the hell out of me. With a problem this hard, the fact that they are down to minor mistakes like this and not major fundamental issues is awesome.
Re: (Score:2)
Lots of people find space interesting and are generally supportive of ongoing research and efforts, but generally maintain a healthy balance of other interests.
Space nuttery is in my opinion defined by an unhealthy and unrealistic obsession with space. These are people who would (or at least have said they would) sell all their worldly possessions for the opportunity to spend some time in space, who would volunteer for a one way trip to mars. Basically a space nutter is someone who spends a fair bit of time
Re: (Score:2)
It's a fairly commonly used term, and I wouldn't really call it a grudge so much as an acknowledgement of the disconnect in reality with those who assume an out of proportion interest in anything involving space.
Re:This test was a successful failure (Score:5, Funny)
If you like it more than he does you are a nutter.
This is really easy stuff.
Re: (Score:2)
Interesting that despite running out of fluid 30 seconds before the crash. It still landed in nearly the exact center of the platform. Is it just that it dosn't take much maneuvering even to cover that distance? Or was the platform moving to 'catch' it I wonder?
Try Again Next Time (Score:5, Insightful)
What gets me most about this is the nonchalant attitude.
"yea we blew up the rocket and the barge, but no biggie. We'll do better next time"
I think that is why nerds get so exited over SpaceX. That attitude of not letting fear of failure dictate future actions.
Re:Try Again Next Time (Score:5, Informative)
To be fair, the pictures I've seen of the barge indicate it came through mostly unscathed. So they only blew up the rocket. :)
hey, are you gonna blow that up? can I have it? (Score:3)
So they only blew up the rocket.
Hey, their competitors would have just thrown it away anyway...
Re: (Score:2)
I just got a look at the vine b/c the site is blocked at my work. My thoughts are:
It was much closer than I thought, and that must be one tough barge.
Re: (Score:2)
It looks like they lost a hydraulic pump for one of their thrusters from the photos I've seen. So not quite unscathed, that was probably tens of thousands of dollars of damage, but that's chump change if they can make it work.
Re: (Score:3)
Gotta agree.
Business in general has become very risk adverse with a few exceptions (spacex and google being the big ones). Many of us feel constrained in this environment where everything we do has to mostly work or we won't get a second change or an opportunity to improve it. Everything has become about risk management and ROI and soul crushing metrics. It's very refreshing to see this kind of apparent "lets just do something we know probably won't work the first time, and keep doing it until it does" atti
Re: (Score:2)
Well, they usually just let it fall in the ocean so I don't quite see the big risk they're taking here. The rocket will be FUBAR anyway, the barge is basically a bulk metal piece and I assume that if they were looking at a high speed impact they would have fired the engines to avoid significantly damaging/sinking the barge. The money is spend on all the R&D on engine control, fins, legs and whatnot. They got nothing to lose in the actual landing attempt, basically they get a free shot with every rocket
Re: (Score:2)
They don't have stock-holders or congressmen holding the purse strings to try and impress. They don't need to downplay or spin the outcome of a test flight because everyone involved knows that a good testing program will have some failures. And in fact finding new failure modes in early testing is better then not finding them at all.
So while to SpaceX this was a useful test; their stocks would be falling right now, sending bean counters into a panic were they publicly traded.
Re: (Score:3)
Fuck you.
Re:Try Again Next Time (Score:5, Insightful)
The fact what they think went wrong was insufficient hydraulic fluid, and not their engineering process that allowed a major mistake to make it into the design and not be detected during testing, is the *real* problem.
It was detected during testing. Their entire retrievable/reusable concept is being developed and tested right now. Their contractual requirement is to put payload into orbit. The landing mechanism is merely an economic advantage for the company that will keep their costs lower; their contracts certainly don't specify it as a requirement.
Some shops use an iterative design process. It usually comes with being new to the market (and thus lacking the funds for extended pre-operative testing).
Some shops even do iterative design as standard practice when they are well-funded.
They were only required to launch supplies to the ISS. The ability to test and refine their landing mechanism is a bonus for the company. Hell, NASA's other contractor doesn't even have a reusable vehicle.
In conclusion: Do you know what we call a service that fulfills its contractual requirements? A success.
Re: (Score:2)
Fix slashdot! (Score:5, Informative)
WTF is going on with the left margin. God damn it, it is broken in every single browser. Are they crapping on classic slashdot to punish us for beta not working?
Re: (Score:3)
yes. Right bar is fucked as well. Mine ends up at the bottom of the scroll.
FIX THIS SHIT, DICE!
Re:Fix slashdot! (Score:4, Informative)
It's all these damn ads they've added.
I swear every other week I find a new ad bar, or some ad has moved and margins are all fucked.
Atleast they keep it interesting...
Re:Fix slashdot! (Score:5, Insightful)
Re: (Score:3)
Only when my disable ads checkbox isnt checked
Re: (Score:3)
What are these ads of which you speak? NoScript and AdBlockPlus, and I haven't seen an ad on Slashdot in YEARS.... except for Slashvertisements, of course.
Re: (Score:2)
it is broken in every single browser
Looks fine in Lynx.
no more RUDs, then? (Score:5, Informative)
To borrow from the KSP forum, that's "Rapid Unscheduled Disassembly". Or, "explosions", to the uninitiated.
Well Done, SpaceX (Score:5, Insightful)
This was the first Falcon 9v1.1 flight [1] with gridfins and [2] sent to land on a teeny tiny little platform at sea (a MUCH smaller target than an aircraft carrier, while descending from MUCH higher than any carrier pilot and having no wings and only VERY limited fuel and throttle-range for lift and control)
It was an excellent display of competence that puts Boeing and Lockheed-Martin to shame; both mega-corps have been sucking billions from the government nipple for many decades without ever once even TRYING to make such an improvement for which they certainly had the expertise and resources. These giant aerospace companies were born as innovative entrepreneurial entities that invested in technological advances and experiments to advance "the state of the art" in order to win their share of the free market.... but after the deaths of their founders they got hired-gun CEOs and moved to a model of only innovating when they could get the government to give them billions of dollars to do it. With many decades of "cost-plus" contracts (where the government pays "whatever it costs, PLUS some percent as profit") the big bloated defense contractors have had no incentive to innovate (ABSOLUTELY ZERO incentive to reduce costs) and have become lazy. SpaceX and more more like it are needed to drive the big old firms into either returning to efficiency and innovation, or bankruptcy.
Re: (Score:3)
And yes, the LEM managed a landing and ascent. On the moon. With no air. And 1/6th the gravity. And using separate ascent and landing stages- the stage that launched to lunar orbit was *not* recovered intact, and the landing stage was dis
trial and error (Score:2)
Re: (Score:2)
Re:trial and error (Score:5, Informative)
It seems SpaceX is relying on a trial-and-error strategy during the development of the soft landing capability of their booster much more than they (or others in the industry) do for other components or capabilities of space launch or other aeronautical systems. I don't see (unmanned) rockets or drones being developed in this fashion. Even large rockets that can achieve orbit will normally be modeled, simulated and tested component-wise to the point that they will usually work at the first or second attempt when the entire system is integrated and tested for the first time. So why is this so different here? Is it just cheaper? Or is it actually that much harder to make the rocket land softly on its own exhaust jet than to make it go into orbit?
It's important to remember that the primary mission was a complete success. The Dragon delivered the cargo to the ISS and is awaiting trash and cargo to return to Earth. This was a post mission experiment meant to collect data. It's very common to completely loose a rocket in the early flights, but that's not what happened here.
SpaceX does what's called LEAN development, which is basically like agile software development. Really all development is incremental, the difference with lean/agile is you admit that instead of pretending that you can design the perfect solution from the start. SpaceX has a huge computer cluster and they model the hell out of everything they do. Then they try it to see how it works in the real world, measure the results and make improvements. The experiments are always done after stage separation in a way that collects important data without putting the mission as risk. You can call that trial and error, but that does the process a disservice.
There have been experimental rockets and landers that land vertically, most notably the DCX. But no one has reentered a first stage of an actual in service rocket, the previous vehicles have always been test platforms and never accelerating to launch vehicle velocities nor going to launch vehicle altitudes. NASA has flown aircraft to collect data from earlier SpaceX missions because no one else has EVER controlled a first stage's return to earth. (Shuttle SRBs were not controlled, just big steel tubes falling from lower and slower than the F9.) The first stage is a long cylinder with blunt ends and it reenters the atmosphere at hypersonic velocities. On top of that, it's a super light weight and fragile airframe. Just getting the thing down to terminal velocity in one piece is a big deal.
The LEAN development model is less expensive than the classic approach. It's also faster and yields really good results. You learn about problems sooner and don't bake them too deeply into your design. Look at it this way, the closest competitor to SpaceX in developing a reusable VTVL rocket is Blue Origin, started by Jeff Bezos. Blue Origin started with more money than SpaceX and before SpaceX. SpaceX is delivering cargo to the ISS, and about to test the Dragon V2 abort system in preparation of flying astronauts in 2017. They are also self funding the development of a much bigger reusable rocket (slightly bigger than the Saturn V). They are doing all of this while providing the least expensive launch prices in the world. Less expensive than Russia. Meanwhile Blue Origin hasn't even reached orbit. They aren't even trying to reach orbit, they are still developing a suborbital rocket, even though they have a number of experienced engineers that worked on the DCX. Oh, to be fair, Blue Origin is developing an engine for use by ULA (and Blue Origin) and doing some work on a man rated capsule. But nothing is anywhere close to flying.
I'll take that kind of progress any day. (Score:5, Insightful)
Hey, as these things go, this was a very very good failure. Consider that we've just progressed from the old reality's typical "the vehicle will splash down somewhere in this 500-square-mile area of the ocean," to Spacex's new reality of "we accurately flew down to a 0.0018-square-mile platform, and borked the touchdown on this first try."
I'll take that kind of progress any day.
First Reports vs. Actual Video (Score:2)
Wicked Cool (Score:2)
parachute (Score:2)
Remind me again, why doing this crazy rocket landing is better than using a parachute recovery like the shuttle boosters did?
Re: (Score:2)
Re:parachute (Score:4, Informative)
Because parachute recovery is a method of salvage, while "crazy rocket landing" is a method of full reuse without refurbishment.
Keep in mind that refurbishing the waterlogged shuttle boosters ended up being 3X more costly than original estimates, much of the nozzle apparatus was completely trashed each time, and the whole process took months to turn around a single booster.
SpaceX is working toward an airplane/airport-style refuel-and-refly-immediately model. That autonomous landing platform is actually a fuel depot, with the eventual intention to refuel first stages and relaunch them immediately for short hops back to a proper launch facility where they can be fitted with a new payload within a day. Crazy? Maybe. Wrong? I don't think so.
Re: (Score:2)
Crazy?
Landing your rocket on a fuel depot. Of course not! What could possibly go wrong? :)
Re:parachute (Score:5, Informative)
Remind me again, why doing this crazy rocket landing is better than using a parachute recovery like the shuttle boosters did?
SpaceX tried parachute recovery with the F9 v1 (the rocket flying now is the v1.1, though really is more like a version 2). After multiple attempts, they could not get the rocket to survive reentry. There are many reasons for this. First of all, the shuttle boasters were big heavy steal tubes. That's fine for a strap on booster, but not so good for the first stage. Rocket stages are very light weight, since the lighter the rocket the more payload it can carry (this is true for boosters too, but it's a different trade off when coupled to a "first stage".) Second the shuttle boosters separated at lower speed and a lower altitude than the first stage of an F9. So you have a much lighter, complex F9 reentering at much higher velocities. Third, the shuttle boosters were more "refurbished" than reused. The goal of SpaceX is to (ultimately) land the first stage and be able to refuel and relaunch it with a minimum of work. Shuttle boosters had to be fished out of the water, disassembled, cleaned, inspected, etc... SpaceX was hoping to use parachutes as a first step, but they always hoped to eventually land the boosters. Their timeline just got accelerated when uncontrolled reentries kept breaking up.
Re: (Score:3)
One of the biggest reasons is that, in the location this is happening, parachutes means "lands in the ocean" which implies that your rocket is going to get bathed in salt water, probably engines first. I'm sure you could design some sort of a deployable cover to cover the engines (although they're have to be vented of fuel and cooled first) that would prevent salt water from entering, but I doubt that would be less complex than this scheme and it would almost certainly be heavier.
Finally, remember that one
Isn't this too complicated? (Score:3)
I mean, If it's already slowed down like this, why not just gently land the rocket into the ocean and take it up with some prepared nets/ropes? IMHO it can save a lot of headache from trying to hit a platform this small.
If the water getting in the rocket is problem, what about a gigantic sheet of plastic on the water surface? (still cheaper and more reliable than hitting the landing pad).
Re:How did they run out of fluid? (Score:4, Informative)
Hydraulic systems are in a loop, with the "spent" fluid recirculating back to the reservoir. How did they "run out"?
Where did the fluid go?
The system is an open hydraulic system. Closed systems require tanks and pumps which carry a mass penalty. They only need the system to function for about 4 minutes. Why bother with a closed system when the functioning period is so short. They will increase the amount of fluid by 50% so this shouldn't happen again. All in all a nearly successful experiment.
Re: (Score:2)
Closed systems require tanks and pumps which carry a mass penalty.
Strictly speaking, you don't need multiple reservoirs for a closed hydraulic system. You only need one, and that reservoir can be your accumulator. In practice we usually have at least two; one is the accumulator, and one of them permits degassing the fluid which can be necessary as it heats up. With an open system you definitely only need the accumulator, and some kind of control valve. On a spacecraft, hopefully you also have a backup. A shuttle valve is one valve that lets you pump fluid in (or from) mul
Re: (Score:2)
Explain your alternative ideology, please.
What about corporations as large/powerful as states? Are they good or bad?
--
Remember, when feeding trolls, be sure to keep your hand flat.
Re: (Score:2)
Or hide in your anonymity and know you are a coward
Quite the bluster from an Anonymous Coward.
Re: (Score:3)
I dunno, I'm happy enough with my voluntary free association with the United States. I'm free to leave if I stop liking it, as are you.
What anti-state people don't seem to grasp is that the very same people who you hate in the government, the people who want to control your life and take things from you, weren't made that way by big government. Just look at Mexico. Big drug cartels (who may or may not be entirely the creation of anti-drug big government) are more powerful than the government. Wherever
Re: (Score:3)
Re: Convenience stores have better video coverage (Score:2)
Convince stores in the middle of the Atlantic Ocean? At night? In foggy weather? I'm sue we will see other camera views but this isn't capturing pics of some twerp stealing potato chips.
Further, I don't recall Musk saying anything along the lines that this was about you.
Re: (Score:3)
The "garbled footage" was a radio signal from the incoming first stage. Getting good communications from a vehicle during re-entry is a hard problem. [wikipedia.org] And a GoPro (at least before this landing attempt) wouldn't have helped much because it would have been on the ocean floor along with the rest of the rocket.
And in the case of this particular landing attempt, it was before sunrise in heavy fog.
Radio coverage (Score:3)
The problem with blackout during a hot re-entry from orbit is plasma from the heatshield or tiles (in the case of the Shuttle) blocking radio signals at Mach 20 or so (about 6 km/second or thereabouts). This wasn't the case of the Falcon first stages as they were never going fast enough in the atmosphere to produce any plasma. If any of them had then the bottom of the stage would have melted since it's mostly lightweight low-melting-point alloys. Those sorts of temps would also have damaged a lot of the mot
Re: (Score:2)
It has landing legs. When it hits at a 45 degree angle (that's a lot more than "slightly wrong"), the legs on that side break and the engine assembly smashes into the landing pad.
Re: (Score:3)
Parachutes don't have the accuracy needed to land on a barge, and splashing down in the ocean means complete disassembly to get the residual salt off all the parts.
The Shuttle SRBs could do parachute recovery with ocean splashdown because they consisted of a small number of very large parts, and needed pressure-washing to get the fuel residue off anyway. Taking a liquid-fuel rocket apart is a much harder task.