SpaceX FH : Falcon Heavy Demo : Feb 6, 2018 : Discussion Thread 2

[envy887]

This is a question I get asked a lot in my launch videos, and Flight Club's excellent web-based simulator helps illustrate the answer.

Orbital launches do appear to pitch down towards the horizon, but are you sure the simulation is accurate? The boosters appear to be landing about 70 kms downrange, and I would have expected something closer to parabolic trajectories for the ballistic phases.

It looks like a perspective view from a location on shore, so the ballistic trajectories do not look parabolic as they would from a side view.

[OneSpeed]

Moving this to discussion.

Orbital launches do appear to pitch down towards the horizon, but are you sure the simulation is accurate? The boosters appear to be landing about 70 kms downrange, and I would have expected something closer to parabolic trajectories for the ballistic phases.

It looks like a perspective view from a location on shore, so the ballistic trajectories do not look parabolic as they would from a side view.

Yes, also the core appears to be landing about 300kms downrange, rather than the 500kms mentioned on the webcast.

[dorkmo]

heres the casting number....  https://forum.nasaspaceflight.com/index.php?topic=44376.msg1792327#msg1792327

looks like they machined the top surface

looks like they might have filled some holes with some welding

also looks like they might have added some material to the tips of some of the down facing peaks

[cscott]

Here's an excellent article by Trevor Mahlmann (ArsTechnica's photographer and a great friend of mine) on what it was like to shoot Falcon Heavy and Elon Musk.

https://arstechnica.com/science/2018/03/how-to-photograph-a-rocket-launch-from-a-rooftop-on-falcon-heavys-historic-day/

Seems like you did us all a solid favor by handling his remote cameras so we readers could get some quality Elon pics.  Thanks!

[speedevil]

Further to the video in this post on the discussion thread.

Counting frames at 1:13, I make the stage going very close to its own length in half a second as it hit, which would make it more like 180MPH than the reported 300MPH just after the landing.
(not that 180MPH is remotely survivable of course).

[intrepidpursuit]

I hadn't realized in the original footage how far off center the core landing on the new pad was. Definitely the farthest off the X we have ever seen.

[jabe]

Further to the video in this post on the discussion thread.

Counting frames at 1:13, I make the stage going very close to its own length in half a second as it hit, which would make it more like 180MPH than the reported 300MPH just after the landing.
(not that 180MPH is remotely survivable of course).

the clip seems to show the crash slowed down..splash post crash seems like in slow mo... so can't time it to get accurate speed... ymmv

[Lars-J]

I guess this footage should end the debate of whether or not a stage will overshoot or undershoot it’s landing spot if the engines fail to light for the landing burn. (But who am I kidding, of course it won’t)

[speedevil]

the clip seems to show the crash slowed down..splash post crash seems like in slow mo... so can't time it to get accurate speed... ymmv

I'm unsure - you don't usually see things of that scale - with water going so fast, and this makes it look slower than it should be as you're implicitly assuming it's smaller than it is, so gravity 'looks' slower, and hence slowed down.

[meekGee]

I guess this footage should end the debate of whether or not a stage will overshoot or undershoot it’s landing spot if the engines fail to light for the landing burn. (But who am I kidding, of course it won’t)

Just wait for the comments that SpaceX clearly photo-shopped the water splash to make the crash look more benign.

[mme]

Further to the video in this post on the discussion thread.

Counting frames at 1:13, I make the stage going very close to its own length in half a second as it hit, which would make it more like 180MPH than the reported 300MPH just after the landing.
(not that 180MPH is remotely survivable of course).

I'm pretty sure Elon said about 300 KPH which is about 180 MPH.

Edit: Nevermind, I misremembered.

[Johnnyhinbos]

No deployed legs...

[Kabloona]

I guess this footage should end the debate of whether or not a stage will overshoot or undershoot it’s landing spot if the engines fail to light for the landing burn. (But who am I kidding, of course it won’t)

Yes, the video clearly shows the stage coming in at an angle and overshooting the ASDS. For those who missed it, the great "overshoot vs. undershoot" debate started here:

https://forum.nasaspaceflight.com/index.php?topic=44778.msg1788585#msg1788585

...and lasted several pages, so is worth revisiting in light of the new video. Hopefully all debaters will view the video and some will see the error of their ways.  Meanwhile, you may bask in the knowledge that you were indeed correct. 

[AC in NC]

I'm pretty sure Elon said about 300 KPH which is about 180 MPH.

https://expeditedtranscripts.com/full-transcript-news-conference-spacex-falcon-heavy-test-flight/

ELON MUSK: Again, I would take any information I give with regard to this with a bit of a grain of salt, because I’ll tell you the information that I have but the information I have may be incorrect, so it could be way off.

So the information I received was that we hit the water at about 300 miles an hour, 500 kilometers – roughly 500 kilometers an hour, so that’s hard, and about 100 meters away from the ship. So – which was enough to take out two thrusters and shower the deck with shrapnel. (Laughter.)

[Steven Pietrobon]

Starman unedited. (Ducks and runs for cover :-)

[penguin44]

I also noticed that the center core did not have deployed landing legs. Although now that as I type I am thinking that the stage was at a super high speed and the legs won't deploy above a certain speed. I've flown some aircraft that won't let you drop the gear above a certain speed. (you can use manual override)

[kevinof]

probably more can't than won't deploy.  I suspect the windage at that speed may have prevented them from deploying at all.

[rsdavis9]

So I like the separation video showing the struts separating.  Also is there any references/videos/diagrams of the center booster and side core separation/attachment system?

[Jcc]

So I like the separation video showing the struts separating.  Also is there any references/videos/diagrams of the center booster and side core separation/attachment system?

Seems to have a gas piston pusher to give the boosters a shove off, which makes sense, and consistent with SpaceX preferred methods.

[francesco nicoli]

when is the next FH flight scheduled?