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Longer Video Shows How Incredibly Close Falcon Stage Came To Successful Landing
Bruce Perens writes In the video here, the Falcon 9 first stage is shown landing with a tilt, and then a thruster keeps the rocket vertical on the barge for a few seconds before it quits, followed by Kabooom with obvious significant damage to the barge. It looks like this attempt was incredibly close to success. Given fixes, a successful first-stage recovery seems likely.
You can see a lot more if you go to 1080 HD and full screen. There's some large piece of equipment, perhaps the motor head for one of the barge's corner thrusters, being thrust off of the barge in flames.
It looks like they'll need to do a lot of work on the barge. The support ship Go Quest and the tug Elsbeth III seem to be back in Jacksonville according to vessel tracking sites. There is a Carnival cruise ship that parks next to the barge's dock every 4 days, so we will probably see photos from its bow netcam if we don't see them otherwise.
Oh, check out this newscast. At 2:43, CBS News uses a sequence a SpaceX fan produced with Kerbal Space Program to illustrate how the landing is supposed to work.
Bruce Perens.
The tweet from Musk this morning used the word "sticktion", meaning static friction. And said it was the cause of a phase delay. And then the tweet got deleted.
Bruce Perens.
The forces required are enormous, and even 10m away the rocket thrust would toast most materials. It still has to be caught in a specific orientation to minimize stresses, which means stabilization. As for stopping further, a 10m fall would probably far outstrip the capacity of the structure. (For comparison, more heavily built high power / amateur rockets are designed for touch down forces equivalent to a drop of about 2 meters). The fuel difference is near zero since the full motion of the rocket must be arrested prior to that final "fall".
It also means that the rockets could never land on an arbitrary location, which would be a future goal. Solving it now is a Good Thing (TM).
Is it just my observation, or are there way too many stupid people in the world?
The F9 is intended to land with what they call a "Hover Slam" maneuver - the engines decelerate it to zero right above the surface in as little time as possible. The Merlin engines have a limited throttle range, and with the stage empty, just one engine firing at the lowest throttle setting has a thrust-to-weight ratio somewhere around 1.8, so it can't hover. It would decelerate to zero and then start to lift off again if the engine isn't shut off, you'd need a TWR of 1.0 to just counter gravity and make it hover.
This
fuel needed for the landing is inefficient compared to a splashdown parachute recovery
The barge/ocean is just a temporary measure. The vision is twenty rockets launching a day and returning to the launch site to prep for the next launch.
There were about 120 rocket launches last year. SpaceX's mission statement is to reduce the cost of launches by 100x, and utilization rates go up as costs fall, so it's not just 100x more launches - twenty a day is probably very conservative if they hit their price targets.
Queue the folks who can't imagine what anybody would do with more than 640 launches a year.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
Armadillo Aerospace had their own prototype hovering-gimballing single engine rocket, and Carmack was heavily involved in development of the logic and systems that made that possible.
Close to where I live are large intertidal mudflats. Every other summer some tourist drives a brand new four by four out there and gets stuck. And then, of course, the tide comes in. When the vehicles are recovered two or three tides later, they are insurance write-offs - the electrics, interior, and engine are all beyond repair.
You do not want to immerse something complex and expensive in salt water unless you really, really have to.
I'm old enough to remember when discussions on Slashdot were well informed.
Specifically, from a starting height of 50 feet, and a starting velocity of 50 mph downward, it would require a net acceleration of ~16.5 m/s^2 to come to a stop at ground level.
Since a single (much less nine) Merlin engine can manage 654 kN thrust at sealevel, and a (nearly) empty Falcon 9 first stage masses under 20000 kg, a Falcon first stage is capable of >32.7 m/s^2 acceleration (assuming only one engine burning, of course). Which is more than plenty to allow it to come to a stop on the ground from the estimated speed/height of the OP....
"I do not agree with what you say, but I will defend to the death your right to say it"