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SpaceX Landing Attempt Video Released
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.
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?
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Looks like most of my Kerbal Space Program landings.
How can I believe you when you tell me what I don't want to hear?
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.
This and no other is the root from which a tyrant springs; when first he appears as a protector - Plato (423 to 327 BC)
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.
"There are lies, there are damn lies, and there are statistics"
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".
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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?
he tweeted
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.
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To borrow from the KSP forum, that's "Rapid Unscheduled Disassembly". Or, "explosions", to the uninitiated.
Political debates have me rolling my eyes so much I think I got optical whiplash. I should sue. - Foamy The Squirrel
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.
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.
I think not...(*poof*)
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.
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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.
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