Author Topic: SpaceX F9 : Starlink v1.0 L16 : KSC LC-39A : 20 Jan 2021 (1302 UTC) (Read 71528 times)

Jansen · « **Reply #100 on:** 01/20/2021 01:01 pm »

Acquisition of signal Tasmania

RocketLover0119 · « **Reply #101 on:** 01/20/2021 01:07 pm »

Starlink deploy confirmed! Another 60 happy sats on their way.

Jansen · « **Reply #102 on:** 01/20/2021 01:09 pm »

Successful payload deployment just SE of Australia

FutureSpaceTourist · « **Reply #103 on:** 01/20/2021 01:09 pm »

https://twitter.com/spacex/status/1351894372426498049

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Deployment of 60 Starlink satellites confirmed

eeergo · « **Reply #104 on:** 01/20/2021 01:09 pm »

Deployment of the 60 spacecraft.

zubenelgenubi · « **Reply #105 on:** 01/20/2021 01:15 pm »

Some observations leading to satellites deployment:
Solid oxygen "flower" grown on a second stage valve.
"Tiny" Moon passing through camera view as the stage rotated on its pitch axis.

FutureSpaceTourist · « **Reply #106 on:** 01/20/2021 01:40 pm »

twitter.com/nextspaceflight/status/1351900535738142721

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With today's launch, Falcon 9 now has the highest number of consecutive fully successful missions of any active orbital-class rocket. Falcon's 77 consecutive successes in a row move it ahead of Atlas V by one mission.

https://twitter.com/nextspaceflight/status/1351901482501763074

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This tally does include Crew Dragon's Inflight Abort Test, which is a debatable inclusion due to the suborbital nature of the flight. I include it as it utilized a very close to standard Falcon 9. However, if you disagree with it, just wait a few days.

FutureSpaceTourist · « **Reply #107 on:** 01/20/2021 01:48 pm »

SpaceX launch photo by Ben Cooper

FutureSpaceTourist · « **Reply #108 on:** 01/20/2021 02:32 pm »

More SpaceX photos

https://twitter.com/spacex/status/1351913896274128898

scr00chy · « **Reply #109 on:** 01/20/2021 03:27 pm »

This launch also marked the shortest time between JRTI landings at 12 days.

zaitcev · « **Reply #110 on:** 01/20/2021 04:32 pm »

In the mission video for Starlink L16 it was plainly noticeable that the rocket dialed a significant angle of attack after MaxQ, which continued almost until the separation. The most obvious confirmation that it wasn't just an artifact of the view from the ground came when the booster straightened itself out right before the separation. You can see Earth moving in the background together with the plume becoming symmetric.

Anyone has a good guess what this strange maneuver is for?

The screencaps show the visible angle between the exhaust and the rocket body and the 2 back-to-back captures before and after the moment when the rocket straightened up ahead of the MECO.

zaitcev · « **Reply #111 on:** 01/20/2021 04:37 pm »

My personal guess is that one of the Merlins did not come out of the lower throttle setting after MaxQ. The rest of them tilted to compensate. The engine continued to operate at reduced thrust until MECO. As other 8 engines started to throttle down ahead of MECO, their thrust equated that of the underperforming engine and the rocket straightened out.

the_other_Doug · « **Reply #112 on:** 01/20/2021 04:40 pm »

Whereas I would guess it's due to upper level winds. Or a programmed lofting of the trajectory just before MECO, perhaps to shape the F9 first stage's recovery trajectory.

soltasto · « **Reply #113 on:** 01/20/2021 04:48 pm »

This happens most of the times, especially for mission with ADSD landings.
My guess is that they take advantage of the little available lift to compensate a bit of gravity losses

zaitcev · « **Reply #114 on:** 01/20/2021 04:52 pm »

Thanks. I also thought that the direction of the tilt seemed suspiciously convenient.

ugordan · « **Reply #115 on:** 01/20/2021 05:05 pm »

F9 is far from the only rocket that does this, see a very obvious case of Delta II:

That one only had 3 solids so the trajectory shaping was very obvious.

ZachS09 · « **Reply #116 on:** 01/20/2021 05:16 pm »

Quote from: SMS on 01/19/2021 04:02 pm

https://twitter.com/TSKelso/status/1351572205235101697

Per this tweet, I predicted the T0 would be 13:02:22 UTC.

Total mission duration is 1 hour, 4 minutes, 32 seconds. Subtract that from 14:06:54, which gives the T0 estimate.

wannamoonbase · « **Reply #117 on:** 01/20/2021 07:59 pm »

Quote from: zaitcev on 01/20/2021 04:52 pm

Thanks. I also thought that the direction of the tilt seemed suspiciously convenient.

I noticed it too and thought it was the camera angle. Interesting to know that they can be that flexible on using the vehicle's body. Pretty cool.

vaporcobra · « **Reply #118 on:** 01/20/2021 08:59 pm »

LauncherOne was an extreme example but it also just demonstrated the use of a high-alpha maneuver to generate vertical lift.

zaitcev · « **Reply #119 on:** 01/20/2021 09:04 pm »

Quote from: wannamoonbase on 01/20/2021 07:59 pm

I noticed it too and thought it was the camera angle.

We can see how the attitude changes a few seconds before MECO, and the plume shape changes with it. So it's most definitely not just the camera. But as others mentioned, this sort of thing is rather common. I just wish to know what the benefit is.

Regarding the interaction with the relative wind, I thought it odd that the program calls for the rocket to tilt to a set angle, stay like that for a good minute, then abruptly return to centered attitude before MECO. If this were an airplane, the angle of attack would be changing gradually according to the airspeed and thickness of the atmosphere.