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Makes me wonder if they just leave them on the ground of the ocean or recover them? ...I bet otherwise the Russians or Chinese would love to get their hands one of them :)
this footage give a real sense of how close they are to getting it right
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It burns three times after the second stage detaches. The first is to get the landing zone closer to the takeoff, the second slows it down from 1300 m/s to about 250 m/s, the third slows it to (hopefully) 0 m/s on the landing pad. Here's a diagram: http://media2.s-nbcnews.com/i/newscms/2014_51/812491/141217-... If the 'x-wings' are what I think you're referring to, they're the landing legs. They are shaped like that…
What's the difference between the tests on earth (as seen on youtube etc) where the engine runs the whole time and seems to display good throttle control and this type of landing?
Of course, these barge landings are the first high-velocity tests, so there'll be kinks to work out.
It must be amazing working in a field where failure is almost as exciting as success. What's the main obstacle to slowing down and stabilizing the rocket on its descent to the platform? Is it just a matter of speed or also the shape of the rocket and its center of gravity? Would a set of 3 parachutes might slow it down a little bit or at the very least straighten it before the rockets need to kick in saving some fuel…
I don't think incoming velocity is much of a problem. Terminal velocity is gonna be no more than 90 m/s. The engines on that stage are more than capable of slowing it down--and fast. In fact, they're too powerful--it can't hover.
Why did it explode in such a dramatic fashion? I thought the booster was almost entirely empty when it returns to the barge.
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Watching it made me realize I only had an abstract idea of how difficult it was to even attempt this. It's insanely hard, and they're so close!
Yes its a very hard problem but what makes it hard ? Is it engineering of the components, algorithms or expensive tests and economics of it ? Maybe people before Elon Musk were not interested in solving this problem not because its technically hard problem but because their existing business model is much more lucrative.
It could be as simple as a huge ring of cable that just closes around the top of the rocket, then pulls it tight on all sides- like the guidelines on a tower to keep it stable.
Maybe they don't want to do that because they think they can do it without it?
I wonder what happened there. Looks at 4 seconds the guidance system figured it needed to pull an ultra manoeuvre to slow the the horizontal speed(was drifting left) but ended up with a solution putting the rocket upright again at nearly 0m. If it would have left some altitude for stabilizing I think they would have had it. Arm chair rocket science is fun.
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What's the difference between the tests on earth (as seen on youtube etc) where the engine runs the whole time and seems to display good throttle control and this type of landing?
The Grasshopper tests had a full tank of fuel and (if I recall) additional ballast, to counteract the thrust of the engines. That's what allowed them to hover and perform the various low-velocity translation tests. Of course, these barge landings are the first high-velocity tests, so there'll be kinks to work out.
I was impressed by how small the barge looked compared with the F9 it's clever that the F9 can autonomously target such a small area. If they keep targeting 'Just Read the Instructions' by the time land based landings come to be it will be nailed. Awesome stuff!