SpaceX F9 : Starlink v1.0 L12 : KSC LC-39A : October 6, 2020 (11:29 UTC)

[FutureSpaceTourist]

https://twitter.com/kyle_m_photo/status/1314558776972922883

The cap is attached to B1058.3 and the leg lifting lines are lowered. #SpaceXFleet #SpaceX

[FutureSpaceTourist]

https://twitter.com/kyle_m_photo/status/1314579331260317696

B1058.3 is in the air. #SpaceXFleet #SpaceX

https://twitter.com/kyle_m_photo/status/1314581787721584641

Way up there now. #SpaceXFleet #SpaceX

[FutureSpaceTourist]

Love this

https://twitter.com/johnpisaniphoto/status/1314678526075973638

A golden hour return to port yesterday for this particular Falcon 9. Thrice flown and scorched from re-entry, yet still gleaming in the setting Space Coast sun.
@SpaceX #Falcon9 #Rocket @PortCanaveral #SpaceCoast

[Comga]

Did anyone else notice the flash of LOC Cam in the webcast?
I’ve been missing the LOX Cam.
It’s such a neat detail and possibly unique to SpaceX among current launchers. 
The Saturn rockets  did this with ejectable film canisters, at least until they had to “strip down” to carry the LEM, and at least for kerosene and LH2 tanks. 
Has any other rocket done this?

[Arb]

Did anyone else notice the flash of LOC Cam in the webcast?
...

Steven Pietrobon on launch day:

A single frame of the LOX tank slipped through at Diego Garcia AOS. :-)

[LouScheffer]

A single frame of the LOX tank slipped through at Diego Garcia AOS. :-)

From this we can guess about how much margin is left, assuming the coast thrusters are scrunching the LOX down into the dome.  From the picture below, we can approximate the LOX dome as a portion of a sphere of 2.35 meter radius.   (the rocket is 3.7 meters and 762 pixels, circle is 1044 pixels).

Now how much volume is contained in a spherical bowl of radius R0, when filled up until the radius of the fluid surface is r?  A little high school calculus (proof left to the reader) shows that if d = sqrt(1-(r/R0)^2) then volume= (2/3-d+d^3/3)*pi*R0^3.  Then given the volume we can find the mass of LOX, at 1141 kg/m^3 (that's at boiling, it might be a little denser from sub-cooling).  Then we can find the remaining seconds of operation at full thrust (though the second stage normally seems to run at 70% thrust or so for orbital maneuvers).  Thrust = 981kN, ISP=348, so flow is 981000/9.801/348 = 287.6 kg/sec.  At a mixture ratio of 2.36 to 1, LOX accounts for 287.6*2.36/(2.36+1) = 202 kg/sec.

As a function of filled radius
pct of radius filled=    0.0%, depth(dipstick)= 0.000m vol=-0.000m^3 mass=  -0.0kg seconds left (FT)=-0.00
pct of radius filled=   10.0%, depth(dipstick)= 0.007m vol= 0.000m^3 mass=   0.4kg seconds left (FT)= 0.00
pct of radius filled=   20.0%, depth(dipstick)= 0.027m vol= 0.006m^3 mass=   6.7kg seconds left (FT)= 0.03
pct of radius filled=   30.0%, depth(dipstick)= 0.062m vol= 0.030m^3 mass=  34.2kg seconds left (FT)= 0.17
pct of radius filled=   40.0%, depth(dipstick)= 0.111m vol= 0.096m^3 mass= 109.4kg seconds left (FT)= 0.54
pct of radius filled=   50.0%, depth(dipstick)= 0.175m vol= 0.238m^3 mass= 271.8kg seconds left (FT)= 1.35
pct of radius filled=   60.0%, depth(dipstick)= 0.257m vol= 0.505m^3 mass= 576.5kg seconds left (FT)= 2.85
pct of radius filled=   70.0%, depth(dipstick)= 0.357m vol= 0.963m^3 mass=1098.8kg seconds left (FT)= 5.44
pct of radius filled=   80.0%, depth(dipstick)= 0.478m vol= 1.702m^3 mass=1942.0kg seconds left (FT)= 9.61
pct of radius filled=   90.0%, depth(dipstick)= 0.625m vol= 2.850m^3 mass=3251.8kg seconds left (FT)=16.10
pct of radius filled=  100.0%, depth(dipstick)= 0.804m vol= 4.596m^3 mass=5243.7kg seconds left (FT)=25.96

plus however much LOX is in the feeder pipe.

From the picture it looks like about 80% of the radius was filled with LOX, so they had about 9.6 seconds at full thrust, or maybe 13 seconds at the 70% thrust they seem to use for orbital maneuvers.  Should be plenty for the brief burp to circularize and then de-orbit.

The first starlink launch LOX tank looks much sketchier.  Although it's not centered, it looks like maybe 60% radius on the average, or 3 seconds of firing left in the tank.

Code in python, if anyone cares to check:

import math
flow = 981000/9.801/348 #981000 newtons, 348 ISP
mr = 2.36
lox = flow * mr/(1+mr)
print(f"LOX flow rate, kg/sec{lox:7.1f}")
r0 = 2.53
print("As a function of filled radius")
for i in range(11):
  fr = float(i)/10
  r = fr*1.85
  d = math.sqrt(1-(r/r0)**2)
  v = (2.0/3.0 - d + d**3/3) * math.pi *r0**3
  mass = v*1141
  seconds = mass/lox
  print(f"pct of radius filled={fr:8.1%}, depth(dipstick)={(1-d)*r0:6.3f}m vol={v:6.3f}m^3 mass={mass:6.1f}kg seconds left (FT)={seconds:5.2f}")

[FutureSpaceTourist]

https://twitter.com/nasaspaceflight/status/1314969190114250756

Starlink mission fairing offload from tarp to trailer... GO Ms. Tree and Ms. Chief deliver their catch right across from @RustysInThePort

Follow along for more full-quality @NASASpaceflight #Fleetcam video updates.

[CraigLieb]

https://twitter.com/trevormahlmann/status/1314331907665080320

🚀#B1058.3🇺🇸

⚙️/⬇️/🖼: tmahlmann.com/photos/Rockets…

And this time we didn't have a landing bingo running......
Does he say how or from where this image was taken?

We could all agree to just use this as the image for the last bingo contest as the method of picking the winner to help us all move forward.  AND change the contest from now on to pick a winner based on the next launch with a viable image to use, rather than a specific launch only.

[FutureSpaceTourist]

https://twitter.com/trevormahlmann/status/1315068725259894784

These two things were once traveling ~5,000 miles per hour in space, came back through the atmosphere, deployed parachutes, soft landed on/nearby some boats & now can be used again🤯 Absolutely mental.

⚙️/⬇️/🖼: tmahlmann.com/photos/Rockets…

[FutureSpaceTourist]

https://twitter.com/gregscott_photo/status/1315797351798317056

SpaceX Starlink 13 - One, two, three & four, all legs up just before sunset today....still standing tonight but I assume it will be laid on the crawler tomorrow morning for transport back to the hanger for refurbishment for the next flight. #NASA #SpaceX #Space #SpaceXFleet

[FutureSpaceTourist]

https://twitter.com/kyle_m_photo/status/1316109359672373254

B1058.3 is off the stand and will be lowered horizontally onto it's transporter soon. #SpaceXFleet #SpaceX

https://twitter.com/kyle_m_photo/status/1316110321984167936

It is tilt time. #SpaceXFleet #SpaceX

[FutureSpaceTourist]

[SMS]

https://twitter.com/TSKelso/status/1316445189393862659

[gongora]

Second stage has been cataloged on Space-Track.

https://twitter.com/Skitt0608/status/1317511793103704067

@planet4589 46669 is the F9 2nd stage rocket body. The team forgot to put it in the list when we cataloged the last batch of sats/rods.

Inclination: 52.99  Apogee: 261km  Perigee: 238km

TLE
1 46669U 20070BS  20290.55527251  .00305404  56129-4  33254-3 0  9998
2 46669  52.9917  32.3428 0017156 329.8735  30.1310 16.08972984  2403

[LouScheffer]

Second stage has been cataloged on Space-Track.

@planet4589 46669 is the F9 2nd stage rocket body. The team forgot to put it in the list when we cataloged the last batch of sats/rods.

Inclination: 52.99  Apogee: 261km  Perigee: 238km

TLE
1 46669U 20070BS  20290.55527251  .00305404  56129-4  33254-3 0  9998
2 46669  52.9917  32.3428 0017156 329.8735  30.1310 16.08972984  2403

So the second stage did not de-orbit?   It looked like it had the fuel to do so, or at least lower the perigee,  from the brief view of the LOX tank during coast.

[zubenelgenubi]

https://twitter.com/planet4589/status/1318966780585512960

Meanwhile from the previous batch [Starlink 13 = Starlink v1.0 Fl. 12] Starlink-1744 appears to have recovered and is now orbit raising at the standard rate (magenta line).

[Chris Bergin]

This is great!

https://twitter.com/TheFavoritist/status/1321217084370669574

[cppetrie]

Second stage reentry predicted today, October 30.  Latest prediction is 14:00 UTC (9 AM Central Time) just east of Houston on an ascending track.  That'll change of course.

5-ish tonnes uncontrolled entry over the central U.S..  ...  But note that the last prediction was at 11:41 UTC, so the time and location could vary substantially.

 - Ed Kyle

How demiseable is the stage expected to be? Are large pieces expected to survive re-entry?

[Bob Shaw]

Roll on Starship, with all stages recoverable!

[Comga]

Second stage reentry predicted today, October 30.  Latest prediction is 14:00 UTC (9 AM Central Time) just east of Houston on an ascending track.  That'll change of course.

5-ish tonnes uncontrolled entry over the central U.S..  ...  But note that the last prediction was at 11:41 UTC, so the time and location could vary substantially.  The predicted window was 30 minutes long, which would be about one-third of an orbit.

 - Ed Kyle

From where are you getting that prediction?
The Satview tracking site shows it at 207 km altitude with a week to go before it decays