4 ms·
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 abo
by sfeng 12y ago
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-launchprofile_f4fcb1ed474952c078a75c07a96cae6f.jpg 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 to have as minimal impact on the air resistance of the ascending rocket as is possible. They open just before landing.
It can't hover. Even just using a single one of the nine engines, the engine can't be throttled down enough for the rocket to hover. The landing method relies on what they call a 'hover-slam', where they fire the engine during landing to slow it down just before it touches.
Landing this is extremely impressive. It is going four times faster than the speed of sound, and they are landing it on a pad smaller than a football field. Vertical landing of a returning rocket has never been done. It's also the key step in the process of dramatically lowering the cost of spaceflight which could usher in a new era of technology around earth, and on other planets.
- monk_e_boy 12y agoAah, grid fins were the things I was thinking of. That first burn must have some complex maths behind it. Do we know anything of their simulation software?
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- 69_years_and 12y agoWhat'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?
- Two9A 12y agoThe 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.
- 69_years_and 12y agoThanks, that would explain that. 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!
- swamp40 12y agoMaybe it needs to hover? There must be something that can be squeezed to throttle it down some more. Call the NASCAR guys with their restrictor plate designs.
- TeMPOraL 12y agoIMO that landing clearly proved suicide burning is working perfectly fine - they just need to fix something to get rid of the remaining lateral velocity.