SpaceX landing

[billvon 2,998]

These stills look like they could have come from a science fiction movie - and the video is even more impressive.

[ryoder 1,590]

Video: https://scontent.cdninstagram.com/t50.2886-16/18316660_811973342289674_4783593347170172928_n.mp4

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

[tkhayes 348]

fucking awesome

[normiss 801]

That burn to roll it over into a landing position is aerodynamically amazing IMO.
It just shouldn't work at that speed!

[BillyVance 34]

Parachutes? Parachutes?? We don't need no stinkin' parachutes!!

"Mediocre people don't like high achievers, and high achievers don't like mediocre people." - SIX TIME National Champion coach Nick Saban

[wmw999 2,452]

Quote

fucking awesome

Perfectly stated!

Wendy P.

There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

[fanya 3]

jfc some humans are really fucking impressive

[councilman24 37]

BillyVance

Parachutes? Parachutes?? We don't need no stinkin' parachutes!!

Time for the jetman jumpers to stand up and land like that.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

[Phil1111 1,149]

COLORADO SPRINGS — SpaceX saw significant cost savings by reusing a Falcon 9 first stage in a launch last week, a key factor for the economic viability of reusable launch vehicles.

SpaceX President Gwynne Shotwell, speaking at the 33rd Space Symposium here April 5, said the company expects to see greater cost savings on future launches of reused Falcon 9 vehicles as the company reduces the amount of refurbishment work it does on the recovered stages.
SpaceX's first previously flown Falcon 9 booster lands after launching SES-10. Credit: SpaceX
SpaceX’s first previously flown Falcon 9 booster lands after launching SES-10. Credit: SpaceX

Shotwell did not give a specific figure for the cost of refurbishing a Falcon 9 first stage that first flew on an April 2016 launch of a Dragon cargo spacecraft so it could launch the SES-10 communications satellite March 30. “It was substantially less than half” the cost of new first stage, she said.

That cost savings, she said, came even though SpaceX did extensive work to examine and refurbish the stage. “We did way more on this one than we’re doing on future ones, of course,” she said...

“Our challenge right now is to refly a rocket within 24 hours. -
http://spacenews.com/spacex-gaining-substantial-cost-savings-from-reused-falcon-9/

China studying reusable rockets similar to SpaceX
http://spacenews.com/china-studying-reusable-rockets-similar-to-spacex/

[quade 4]

normiss

That burn to roll it over into a landing position is aerodynamically amazing IMO.
It just shouldn't work at that speed!

It wouldn't if it was in the thicker air closer to the ground. At a "high enough" altitude, even if you're not quite out of the atmosphere officially (Karman Line), it's close enough to not matter a whole lot.

When you watch a rocket launch you'll almost always hear a call out for Max-Q or Maximum Dynamic Pressure. If somebody sneezed at that moment and the rocket was yawed or pitched just a little bit out of line the entire thing would probably come apart. After that, the aerodynamic forces on the rocket are diminishing.

The really impressive part is the pin-point landing. Landing at all is difficult enough, but when you consider the speeds, energy, momentum, variations in winds at altitudes, rotation of the planet, and some butterfly flapping its wings on the other side of the planet, it is -amazing-.

None of that would be possible without modern computer technology. It would next to impossible to "hand fly" that as a human. Try it yourself in Kerbal Space Program. Try making just a "simple" pinpoint landing on its version of the Moon where you don't have to deal with atmosphere, planetary rotation (well, hardly), and the gravity is about 1/6th. Good luck. Oh, and be sure to give it a shot doing the suicide burn like SpaceX does. Geebus.

quade -
The World's Most Boring Skydiver

[quade 4]

PS

One of the things that's striking about the North Korean missile program is they're roughly where the US was 60 years ago. Let that sink in. Meanwhile, one billionaire's private rocket company is pretty much unquestionably the most sophisticated space program on Earth easily besting anything NASA can do (okay, sure, NASA has reasons, I don't hold it against them).

SpaceX is engineering magic.

quade -
The World's Most Boring Skydiver

[jumpwally 0]

cool stuff,,,how does it not tumble all over the place ?

smile, be nice, enjoy life
FB # - 1083

[BillyVance 34]

jumpwally

cool stuff,,,how does it not tumble all over the place ?

They kind of did in the beginning. A few failed landings, and then they figured things out.

"Mediocre people don't like high achievers, and high achievers don't like mediocre people." - SIX TIME National Champion coach Nick Saban

[billvon 2,998]

>cool stuff,,,how does it not tumble all over the place ?

Good question. A few ways:

1) When it's out of the atmosphere it uses cold-gas (nitrogen) thrusters to orient the stage. There's so little air up there that the thrusters can easily overcome any tendency for the air to tumble it.

2) Once it hits denser air it deploys grid fins, which give it a little bit of aerodynamic stability. Also, as long as it hits the denser air tail-first, the fuel settles to the bottom of the tank. Weight in the bottom means it becomes stable falling tail first.

3) During re-entry, during the time you would expect the most forces on the stage, it burns one of its engines. When its engine is burning it can gimbal it in different directions to keep the stage stable.

4) During landing, it again fires one of its engines to start to brake. During this time it's doing three things. One is using its engine to maintain stability; as it slows down aerodynamic forces no longer stabilize it, so it needs the engine to keep it from tumbling. (There's a lot of gimbaling going on during this time.) The second is using its engine to keep it close as possible to its planned flight path, so it lands on target. It does this by tilting slightly away from vertical and using the engine's thrust to adjust trajectory. The third is throttling the engine's thrust so that it hits zero velocity at zero altitude.

If it sounds like it's hard to do all those things at once, it is. Adding to the problem is that fuel is shifting around, that tilting the stage also adds aerodynamic lift to the problem (when speeds are still high) and that those landing legs add a big amount of drag, which is one reason they are deployed so late (and only when the engine is firing.)

Another problem is that even firing one engine at minimum thrust you have more thrust than you need, so you have to time it just right.

A third problem is that since you can only fire a single engine you don't have roll control. So during the final phase of descent you need to use a combination of those nitrogen thrusters and the grid fins to maintain roll control. But the grid fins don't work at low speeds, so you have to rely entirely on thrusters.

(During one of the first tests the thrusters didn't have enough authority to stop the roll. The stage started to spin up, and started spinning so fast the the fuel centrifuged away from the intake ports; the rocket then flamed out and the stage crashed.)

[DJL 235]

quade

PS

One of the things that's striking about the North Korean missile program is they're roughly where the US was 60 years ago. Let that sink in. Meanwhile, one billionaire's private rocket company is pretty much unquestionably the most sophisticated space program on Earth easily besting anything NASA can do (okay, sure, NASA has reasons, I don't hold it against them).

SpaceX is engineering magic.

Would be amazing if our space program got true funding. Seems like we're always quoting NASA on things yet their funding is entirely political. I wonder if someday they'll only be a regulatory instead of a research and exploration agency.

"I encourage all awesome dangerous behavior." - Jeffro Fincher

[quade 4]

DJL

I wonder if someday they'll only be a regulatory instead of a research and exploration agency.

Folded into the FAA. I can see it, or I can at least see somebody proposing it. I'm not sure who would win in that though because the current funding isn't really all that big as it is. I'm sure there are some Randian types that would like to do away with its funding altogether, but they'd also probably want to get rid of the regulation as well.

I think NASA holds a special place in government as a source of pride. No matter how big of an a-hole a President is (I'm talking Nixon, but if the shoe fits go for it), they can't go too far wrong making a phone call to astronauts doing a mission in space.

It's also a part of the military / industrial complex and a way to dole out some jobs so it gets used as leverage. A very useful thing those in power.

I think there's a balance to be struck between NASA and the billionaire rocketeers. I don't think you'd want the entire thing in private hands as it's also a national security issue, but I can see some advantages in scaling back certain manned missions as long as the billionaire rocketeers have those same dreams. For instance, I see no point whatsoever in NASA pursuing any manned Mars missions as long as that's where Musk is headed.

I'd like to see NASA do more in terms of things that are never going to be financially viable, but are potential planet saviors. Asteroid redirect has huge implications in terms of actually saving the entire planet from disaster as well as enormous commercial spin offs in terms of mining.

quade -
The World's Most Boring Skydiver

[wmw999 2,452]

I see NASA's position kind of the same; the government should do what is felt to be important, that isn't commercially viable, or viable yet (sorry, brenthutch -- sometimes things that aren't commercially viable are still worth doing).

I think the right time was chosen to put more into the commercial world. Commercial entities can take risks that the government just can't. We used to tell new hires, quite honestly, that they were working on a national monument, and that a big enough screw-up could easily end up having to be discussed with congress.

When one of the commercial guys lost a pilot, it was a shame, but not the cause for a multi-year program shutdown. It is for the US space program, just because of all the public navel-gazing. That navel-gazing isn't without value, but it adds seriously to the expense and time.

Wendy P.

There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)