4 ms·

Incredible time-lapse of the landing, from Elon Musk's instagram: https://www.instagram.com/p/BVxysOlA04j/ https://www.instagram.com/p/BVxysOlA04j/ The yawing

Incredible time-lapse of the landing, from Elon Musk's instagram: https://www.instagram.com/p/BVxysOlA04j/ https://www.instagram.com/p/BVxysOlA04j/ The yawing motion at the beginning of the video is because they moved the drone ship to avoid stormy seas, so the stage had to thrust sideways to retarget. In calm weather SpaceX positions the ship right along the ballistic path, so the stage only needs to pitch up and "flip." You can also see the grid fins "pulling up" through the atmosphere to bleed off as much speed as possible. I described the optimization a while back. https://news.ycombinator.com/item?id=14288431 https://news.ycombinator.com/item?id=14288431 Fantastic job to everyone at SpaceX!

vvanders 9y ago
That comment is worth a read, I had no clue they were actually generating lift on the body to reduce fuel/etc. Incredible stuff.
- JshWright 9y ago
  The new and improved grid fins debuted on this flight allow them even greater capabilities in that regard (greater control authority means they can achieve a higher angle of attack).
  - deleted 9y ago
    [deleted]
- schiffern 9y ago
  Thanks. I made a mistake in that comment, saying the lift/drag of the Shuttle was 1. The hypersonic L/D was 1, but during subsonic approach it was 4.5. In hindsight it kinda makes sense that wings do something. :) The maneuver is more noticeable with the new titanium grid fins (needed because the old aluminum ones caught fire from aerodynamic heating). Not only are they larger, but they use a "sawtooth" leading edge that increases control authority. New: https://twitter.com/elonmusk/status/879065552060260352 https://twitter.com/elonmusk/status/879065552060260352 Old: http://www.spaceflightinsider.com/wp-content/uploads/2015/12/4571-spacex_falcon_9_orbcomm_og2-michael_howard.jpg http://www.spaceflightinsider.com/wp-content/uploads/2015/12... They also happen to be the largest titanium forgings in the world. https://forum.nasaspaceflight.com/index.php?topic=42544.340#msg1661163 https://forum.nasaspaceflight.com/index.php?topic=42544.340#...
  - skykooler 9y ago
    Well, the plan is to use forging to make them, but the ones on this rocket were cast as a blank and machined. One presumes that they are still working on the forging system. https://twitter.com/elonmusk/status/878821062326198272 https://twitter.com/elonmusk/status/878821062326198272
- azernik 9y ago
  Saying in aviation: If you put a big enough engine on it, even a brick will fly. In this case, it's "given enough initial velocity and control authority, even a brick will glide", but the spirit is the same.
  - WalterBright 9y ago
    I believe the proper term is "brick sthouse". A few years back a group of engineers decided to prove this by attaching a number of solid fuel rocket engines to a port-a-potty and launched it to great applause.
    - ajuc 9y ago
      In RC planes community it's quite common as well :) With modern brushless engines and LiPo batteries aerodynamics becomes optional. https://www.youtube.com/watch?v=bns5x4pvl5Y https://www.youtube.com/watch?v=bns5x4pvl5Y
Lorenzo45 9y ago
By "pulling up" do you mean tilting? I read your other comment but had trouble understanding the effect. Do you think you could draw a quick diagram?
- schiffern 9y ago
  First off, the perspective is confusing. The camera is located on the right side of the rocket (I'm treating the zenith as "up" and the direction of flight as "forward"). So when it pulls to the left shortly after the engine shuts off, the vehicle is really pitching up while in a steep dive. The goal of this maneuver to lengthen the descent path, which in the absence of an atmosphere would be a pure parabola (or more accurately, a suborbital ellipse). Passing through more air means shedding more velocity due to drag, and therefore less fuel is needed to land. Geometrically the best way to do that is to pitch "nose up." No drawing skills except shitty MSPaint, but that's never stopped me before. https://i.imgur.com/VLYXDOf.jpg https://i.imgur.com/VLYXDOf.jpg
ClassyJacket 9y ago
It's sad to click on that video and see conspiracy theorists claiming that it's poor CG. Seems no matter how great your achievements there will always be people there to try to bring you down.
- 9to5isdead 9y ago
  It always happens, but really, they're just trying to hook anyone they can. When it comes down to it, there is everyone, and they are the else.
- goshx 9y ago
  I love how Elon Musk feeds the trolls like saying launches are done at night because "it's much easier to do the CGI that way" https://twitter.com/elonmusk/status/832480331496185857?lang=en https://twitter.com/elonmusk/status/832480331496185857?lang=...
- nkrisc 9y ago
  There will always be some who slip between the fingers of education lifting us up.

vvanders 9y ago

That comment is worth a read, I had no clue they were actually generating lift on the body to reduce fuel/etc. Incredible stuff.

JshWright 9y ago
The new and improved grid fins debuted on this flight allow them even greater capabilities in that regard (greater control authority means they can achieve a higher angle of attack).
- deleted 9y ago
  [deleted]
schiffern 9y ago
Thanks. I made a mistake in that comment, saying the lift/drag of the Shuttle was 1. The hypersonic L/D was 1, but during subsonic approach it was 4.5. In hindsight it kinda makes sense that wings do something. :) The maneuver is more noticeable with the new titanium grid fins (needed because the old aluminum ones caught fire from aerodynamic heating). Not only are they larger, but they use a "sawtooth" leading edge that increases control authority. New: https://twitter.com/elonmusk/status/879065552060260352 https://twitter.com/elonmusk/status/879065552060260352 Old: http://www.spaceflightinsider.com/wp-content/uploads/2015/12/4571-spacex_falcon_9_orbcomm_og2-michael_howard.jpg http://www.spaceflightinsider.com/wp-content/uploads/2015/12... They also happen to be the largest titanium forgings in the world. https://forum.nasaspaceflight.com/index.php?topic=42544.340#msg1661163 https://forum.nasaspaceflight.com/index.php?topic=42544.340#...
- skykooler 9y ago
  Well, the plan is to use forging to make them, but the ones on this rocket were cast as a blank and machined. One presumes that they are still working on the forging system. https://twitter.com/elonmusk/status/878821062326198272 https://twitter.com/elonmusk/status/878821062326198272
azernik 9y ago
Saying in aviation: If you put a big enough engine on it, even a brick will fly. In this case, it's "given enough initial velocity and control authority, even a brick will glide", but the spirit is the same.
- WalterBright 9y ago
  I believe the proper term is "brick sthouse". A few years back a group of engineers decided to prove this by attaching a number of solid fuel rocket engines to a port-a-potty and launched it to great applause.
  - ajuc 9y ago
    In RC planes community it's quite common as well :) With modern brushless engines and LiPo batteries aerodynamics becomes optional. https://www.youtube.com/watch?v=bns5x4pvl5Y https://www.youtube.com/watch?v=bns5x4pvl5Y

Lorenzo45 9y ago

By "pulling up" do you mean tilting? I read your other comment but had trouble understanding the effect. Do you think you could draw a quick diagram?

schiffern 9y ago
First off, the perspective is confusing. The camera is located on the right side of the rocket (I'm treating the zenith as "up" and the direction of flight as "forward"). So when it pulls to the left shortly after the engine shuts off, the vehicle is really pitching up while in a steep dive. The goal of this maneuver to lengthen the descent path, which in the absence of an atmosphere would be a pure parabola (or more accurately, a suborbital ellipse). Passing through more air means shedding more velocity due to drag, and therefore less fuel is needed to land. Geometrically the best way to do that is to pitch "nose up." No drawing skills except shitty MSPaint, but that's never stopped me before. https://i.imgur.com/VLYXDOf.jpg https://i.imgur.com/VLYXDOf.jpg

ClassyJacket 9y ago

It's sad to click on that video and see conspiracy theorists claiming that it's poor CG. Seems no matter how great your achievements there will always be people there to try to bring you down.

9to5isdead 9y ago
It always happens, but really, they're just trying to hook anyone they can. When it comes down to it, there is everyone, and they are the else.
goshx 9y ago
I love how Elon Musk feeds the trolls like saying launches are done at night because "it's much easier to do the CGI that way" https://twitter.com/elonmusk/status/832480331496185857?lang=en https://twitter.com/elonmusk/status/832480331496185857?lang=...
nkrisc 9y ago
There will always be some who slip between the fingers of education lifting us up.