Author Topic: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION  (Read 229477 times)

Offline Steven Pietrobon

  • Member
  • Senior Member
  • *****
  • Posts: 19578
  • Adelaide, Australia
    • Steven Pietrobon's Space Archive
  • Liked: 7414
  • Likes Given: 993
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #400 on: 05/28/2016 06:49 am »
Mvac thrust can vary from 80 to 210 klbf (356-934 kN). Throttling started soon after second stage second ignition.

Second stage cutoff at 36440 km/h (10,122.2 m/s relative, 10,531.2 m/s inertial).

Simple launch animation. I've enhanced these to make them a bit clearer.

Fairing separation incorrectly shown after second stage first cutoff.

Geosynchronous altitude correctly show as about 36,000 km.
« Last Edit: 05/28/2016 06:56 am by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Steven Pietrobon

  • Member
  • Senior Member
  • *****
  • Posts: 19578
  • Adelaide, Australia
    • Steven Pietrobon's Space Archive
  • Liked: 7414
  • Likes Given: 993
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #401 on: 05/28/2016 06:52 am »
Spacecraft separation.

A happy set of presenters.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Elmar Moelzer

  • Senior Member
  • *****
  • Posts: 3293
  • Liked: 665
  • Likes Given: 945
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #402 on: 05/28/2016 07:01 am »
So what is that black tarp over the second stage engine all about? Is this new? I cant remember seeing it before.

Offline Jarnis

  • Full Member
  • ****
  • Posts: 1160
  • Liked: 620
  • Likes Given: 163
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #403 on: 05/28/2016 07:27 am »
So what is that black tarp over the second stage engine all about? Is this new? I cant remember seeing it before.

Been there at least since F9 FT started to fly.

Offline Elmar Moelzer

  • Senior Member
  • *****
  • Posts: 3293
  • Liked: 665
  • Likes Given: 945
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #404 on: 05/28/2016 07:47 am »
So what is that black tarp over the second stage engine all about? Is this new? I cant remember seeing it before.

Been there at least since F9 FT started to fly.
Ha! Somehow I never noticed it! What is it for?

Offline NovaSilisko

  • Full Member
  • ****
  • Posts: 1828
  • Liked: 1435
  • Likes Given: 1301
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #405 on: 05/28/2016 09:15 am »
So what is that black tarp over the second stage engine all about? Is this new? I cant remember seeing it before.

Been there at least since F9 FT started to fly.
Ha! Somehow I never noticed it! What is it for?

Thermal control seems most likely. They don't want to risk a restart failure from frozen lines ever again.

Online Paul_G

Note the torque on entry burn engine shutdown.

Also, looks like they aim for a near miss off the edge of the barge until braking burn engine starts. Then the redirect to the center of the barge.

You also can note that the grid fins roast after the entry burn before transonic.

I wonder if this gives us a clue as to why the impact point for the SES 9 recovery attempt was where it was - watching this landing, you can see how a landing burn that didn't quite work our for what ever reason would end up with a fast moving stage coming in to the corner of the droneship.

Paul

Offline corrodedNut

  • Full Member
  • ****
  • Posts: 1543
  • Liked: 213
  • Likes Given: 130
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #407 on: 05/28/2016 12:54 pm »
Note the torque on entry burn engine shutdown.

Also, looks like they aim for a near miss off the edge of the barge until braking burn engine starts. Then the redirect to the center of the barge.

You also can note that the grid fins roast after the entry burn before transonic.

I wonder if this gives us a clue as to why the impact point for the SES 9 recovery attempt was where it was - watching this landing, you can see how a landing burn that didn't quite work our for what ever reason would end up with a fast moving stage coming in to the corner of the droneship.

Paul

Just because the stage is *pointing* a certain direction doesn't necessarily mean that it is *aiming* for the same location.

Offline gregpet

  • Member
  • Posts: 49
  • Liked: 14
  • Likes Given: 43
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #408 on: 05/28/2016 01:13 pm »
I wonder if you will start seeing experiments with the re-entry burn.  Different profiles of burn times, engine firings (maybe just 2 outboard instead of all three), etc to help reduce propellant usage so that they can increase margin on the landing burn.  It seems like the landing burn will need to be increased to slow S1 for these higher velocity launches (or much stronger landing legs that will add weight).

All that said, you have to survive the re-entry to get the opportunity to try a landing so maybe not a lot of margin there either!


Offline StevenV

  • Member
  • Posts: 10
  • Liked: 0
  • Likes Given: 1
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #409 on: 05/28/2016 02:15 pm »
Did anyone notice from the video, or know of, any new fairing recovery experiments with this launch?

It was mentioned in the webcast that they're working on fairing recovery, but nothing specific.

Offline testguy

  • Full Member
  • ***
  • Posts: 331
  • Clifton, Virginia
  • Liked: 285
  • Likes Given: 238
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #410 on: 05/28/2016 02:37 pm »
Anyone notice a second cheer from employees within a minute after the employees cheered for the landing?  May have been for a fairing video they could see but we didn't.

Offline cscott

  • Senior Member
  • *****
  • Posts: 2952
  • Liked: 2061
  • Likes Given: 666
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #411 on: 05/28/2016 02:42 pm »
No, the cheer was for second stage MECO1 SECO1, which happens very shortly after first stage landing.

Edit: SECO not MECO, thanks @baldusi.
« Last Edit: 05/28/2016 03:08 pm by cscott »

Online ugordan

  • Senior Member
  • *****
  • Posts: 7773
    • My mainly Cassini image gallery
  • Liked: 2008
  • Likes Given: 467
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #412 on: 05/28/2016 03:08 pm »
Note the torque on entry burn engine shutdown.

What looks to me like is happening is the reentry burn is done with a certain angle of attack (going back to CRS-4 IR footage, there were hints of this in the plume asymmetry), you can tell the exhaust appears the be swept by predominantly to the left. Near the end of the burn, aero-torque becomes significant, but the engines burning and having control authority still maintain that AoA. Once shutdown, the stage immediately relaxes to zero AoA position (or at least to the limits of the grid fin authority) due to airflow.

Online ugordan

  • Senior Member
  • *****
  • Posts: 7773
    • My mainly Cassini image gallery
  • Liked: 2008
  • Likes Given: 467
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #413 on: 05/28/2016 03:12 pm »
No, the cheer was for second stage MECO1 SECO1, which happens very shortly after first stage landing.

Edit: SECO not MECO, thanks @baldusi.

SECO happened more than a minute prior to the 2nd cheer. I'm pretty sure they were cheering because they got the ASDS video back after the dropout and the stage was still standing. Rewatch the hosted stream and look at the mission control background.

Offline llanitedave

  • Senior Member
  • *****
  • Posts: 2169
  • Nevada Desert
  • Liked: 1358
  • Likes Given: 1599
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #414 on: 05/28/2016 03:25 pm »
Not sure if this has been discussed before, but what about that "tarp"? covering part of the second stage engine? Is that some sort of extra insulation for the restart later, or what is the purpose of it? I don't think I have seen it before.

It was there and I made a post mentioning it during the previous mission.  I don't know when they started using it.
"I've just abducted an alien -- now what?"

Offline RedSky

  • Veteran
  • Full Member
  • ****
  • Posts: 494
  • Liked: 62
  • Likes Given: 2
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #415 on: 05/28/2016 03:56 pm »
This take on the on-board video is pretty interesting.  While it has been slowed down a bit (.25)... what makes this great is he tracks the location of OCISLY most of the way down.  I tried doing this by keeping track of cloud patterns, and it seems he's gone and done it really well.

« Last Edit: 05/28/2016 03:57 pm by RedSky »

Offline llanitedave

  • Senior Member
  • *****
  • Posts: 2169
  • Nevada Desert
  • Liked: 1358
  • Likes Given: 1599
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #416 on: 05/28/2016 04:01 pm »
This take on the on-board video is pretty interesting.  While it has been slowed down a bit (.25)... what makes this great is he tracks the location of OCISLY most of the way down.  I tried doing this by keeping track of cloud patterns, and it seems he's gone and done it really well.



This is a good perspective to look for wobble from the asymmetrical crushing of the leg's shock absorbers.  I don't see any.
"I've just abducted an alien -- now what?"

Offline sewebster

  • Full Member
  • **
  • Posts: 295
  • British Columbia
  • Liked: 186
  • Likes Given: 139
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #417 on: 05/28/2016 04:02 pm »
The TVC actuator was off in yesterdays attempt.

What does this mean?

Offline Davp99

  • Full Member
  • **
  • Posts: 232
  • Fall River, MA
  • Liked: 49
  • Likes Given: 257
Re: SpaceX Falcon-9 - Thaicom-8 - May 27, 2016 - DISCUSSION
« Reply #418 on: 05/28/2016 04:12 pm »
For a minute I thought John Federspiel was Clark Kent.. 8)
You Only Live Twice

Offline Wolfram66

Around :19 sec of sped up video, you can see the transonic shockwave briefly as stage drops below supersonic velocity

Tags: