SpaceX Falcon 9 : Telstar 19 Vantage : July 22, 2018 - DISCUSSION

[input~2]

From the Catalog:2018-059A    43562    TELSTAR 19V    317.93 minutes    27.02 degrees    17862 km    243 km

[IainMcClatchie]

I noticed two odd things about the upper stage burn.

First at 17:46 in the video (), you can see that a few seconds after the second stage has started up the flexible reflective fabric around the upper engine suddenly puffs up.  Does anyone know why that would happen?

Then, after a few more seconds, something at the bottom of the fabric covered area on the MVac makes a jerky motion about once per second.  I've circled the area where it happens in the attached picture.  Does anyone know what that might be?

Thanks!

[tyrred]

The mylar blanket around the MVAC base is a beast of it's own, it has exhibited similar behavior over many of the past launches.  Go back and watch the last few launches for the beating heart of the Mvac.  Exhaust ports/relief valves in action?

[Jarnis]

You are looking at it in vacuum. Even a tiny bit of gas inside the blanket would "puff it up". Also once it is "puffed up", there is nothing to make it collapse again. Even if all that gas just escapes from under the blanket, it stays puffed up unless something pushes it from the outside.

[Steven Pietrobon]

Could you compare with JCSAT-16? It's a close match telemetry-wise, but the final orbit from F9 was 184 km × 35,912 km × 20.85°.

Using my all singing, all dancing GTO program I get the following values. Difference is 592 m/s. For those who don't have my program, it is attached.

Enter initial perigee height (km): 243
Enter initial apogee height (km): 17863
Enter required inclination change (deg): 27
theta1 =  0.34 deg, dv1 =  479.9 m/s
theta2 = 26.66 deg, dv2 = 1793.4 m/s
dv = 2273.3 m/s

Enter initial perigee height (km): 184
Enter initial apogee height (km): 35912
Enter required inclination change (deg): 20.85
theta1 = 20.83 deg, dv1 = 1678.8 m/s
theta2 =  0.02 deg, dv2 =    2.5 m/s
dv = 1681.3 m/s

[envy887]

You are looking at it in vacuum. Even a tiny bit of gas inside the blanket would "puff it up". Also once it is "puffed up", there is nothing to make it collapse again. Even if all that gas just escapes from under the blanket, it stays puffed up unless something pushes it from the outside.

Since the vehicle is accelerating, every part of it is under the force of its own weight. If it is disturbed by a puff of gas, it could "fall" back to it's original position.

[mn]

You are looking at it in vacuum. Even a tiny bit of gas inside the blanket would "puff it up". Also once it is "puffed up", there is nothing to make it collapse again. Even if all that gas just escapes from under the blanket, it stays puffed up unless something pushes it from the outside.

Sounds good in theory but all the videos show it repeatedly puffing

[Elmar Moelzer]

Seeing the stage returning on the droneship, it seems like it looks pretty clean considering that this was a pretty hot return. At least to me, it looks a lot cleaner than previous returned stages.

[IainMcClatchie]

I'm trying to imagine what would cyclically puff on an upper stage engine.  I thinking it wouldn't be anything to do with the main combustion path, but rather the guidance system.

A 1 Hz cycle seems slow, but maybe when the thrust vector control tweaks the firing direction of the MVac, it either leaks a little propellant into the mylar bag (inflating it), or it causes the exterior gas pressure around the top of the MVac to momentarily rise, which collapses the bag a little against an extremely tiny interior pressure.

The upper stage uses cold gas thrusters for roll control, right?  Maybe those things firing impinge on the bag a little.

[MarekCyzio]

Anybody noticed that one of the LOX tank panels is significantly darker?

[cppetrie]

Will be interesting to see if they fold up legs or remove them as they did with the first Block 5.

[Alexphysics]

It seems they have disconnected the hydraulics from what The Aerospace Geek said yesterday on twitter so it's quite possible they'll remove them instead of folding them up. We'll see what happens

[ugordan]

Anybody noticed that one of the LOX tank panels is significantly darker?

Even on the 1st block 5, I could discern (I think in prelaunch photos) that the top section of the LOX tank had a slightly different look, the area where the grid fins lockdown points are. I wonder if they're experimenting with different hydrophobic coatings or something.

It would also be interesting to know whether the noticeably less soot being deposited is due to such a coating or the fact they replaced the TPS around the engine area.

[Alexphysics]

It seems they're going to manually retract the legs with cables running down from the lifting cap to the legs

This was the rumor that was going on since yesterday about the leg retraction:

https://twitter.com/MatthewCable6/status/1022285498612690944

Now it seems real:

https://twitter.com/ThAerospaceGeek/status/1022507131331911680

Edit: Another picture in this tweet (I don't know how to add photos here) of the cables being lowered down from the cap to the bottom

https://twitter.com/ken_kremer/status/1022514478355763200

[Johnnyhinbos]

It seems they're going to manually retract the legs with cables running down from the lifting cap to the legs

This was the rumor that was going on since yesterday about the leg retraction:

https://twitter.com/MatthewCable6/status/1022285498612690944

Now it seems real:

https://twitter.com/ThAerospaceGeek/status/1022507131331911680

Edit: Another picture in this tweet (I don't know how to add photos here) of the cables being lowered down from the cap to the bottom

https://twitter.com/ken_kremer/status/1022514478355763200

Personally I find this highly suspect. It's been common practice for SpaceX to run guy wires from cap to automatic tensioners on the ground to keep the rocket stable. To me these images look like they are rigging those lines. I'd be happy to be proven wrong however...

[envy887]

It seems they're going to manually retract the legs with cables running down from the lifting cap to the legs

This was the rumor that was going on since yesterday about the leg retraction:

https://twitter.com/MatthewCable6/status/1022285498612690944

Now it seems real:

https://twitter.com/ThAerospaceGeek/status/1022507131331911680

Edit: Another picture in this tweet (I don't know how to add photos here) of the cables being lowered down from the cap to the bottom

https://twitter.com/ken_kremer/status/1022514478355763200

Personally I find this highly suspect. It's been common practice for SpaceX to run guy wires from cap to automatic tensioners on the ground to keep the rocket stable. To me these images look like they are rigging those lines. I'd be happy to be proven wrong however...

They are still runnign the guy wires; however, the guy wires appear to be indexed at 45 degree angles in between the legs, while the pulleys and drop cables are indexed directly over the legs.

See Julia's picture here:
https://twitter.com/julia_bergeron/status/1022548915953065984

[TOG]

Were  the fairings halves  recovered?

If you mean were they caught by a ship with the net on it?  No.  If the fairings had the recovery hardware installed, they may get picked up from the ocean surface.  But SpaceX doesn't currently have a fairing catching ship on the east coast.  Their only one Mr. Steven, which operates out of Los Angeles and attempts catching fairing halves from launches out of VAFB.  Next attempt will be on the upcoming Iridium 7 launch.

This is an actual headline on CNN:
       SpaceX loses multi million dollar fairing

The headline doesn't mention that the launch and primary mission were successful, nor does it mention that SpaceX landed the first stage in the worst conditions ever.  Nope, the headline is about how SpaceX FAILED to catch the fairing.

Wow, are we disappointed in SpaceX for failing to do something that has NEVER been done by anyone before.

[TripleSeven]

Were  the fairings halves  recovered?

If you mean were they caught by a ship with the net on it?  No.  If the fairings had the recovery hardware installed, they may get picked up from the ocean surface.  But SpaceX doesn't currently have a fairing catching ship on the east coast.  Their only one Mr. Steven, which operates out of Los Angeles and attempts catching fairing halves from launches out of VAFB.  Next attempt will be on the upcoming Iridium 7 launch.

This is an actual headline on CNN:
       SpaceX loses multi million dollar fairing

The headline doesn't mention that the launch and primary mission were successful, nor does it mention that SpaceX landed the first stage in the worst conditions ever.  Nope, the headline is about how SpaceX FAILED to catch the fairing.

Wow, are we disappointed in SpaceX for failing to do something that has NEVER been done by anyone before.

just saw the CNN story it was in my view not that negative I guess mileage might vary

[Chris Bergin]

I pointed out the poor headline. (Note the headline is the reference, not the article).

Some journalists thought it was fine. (I didn't). Interesting thread:

https://twitter.com/NASASpaceflight/status/1022246752861282305

[envy887]

Were  the fairings halves  recovered?

If you mean were they caught by a ship with the net on it?  No.  If the fairings had the recovery hardware installed, they may get picked up from the ocean surface.  But SpaceX doesn't currently have a fairing catching ship on the east coast.  Their only one Mr. Steven, which operates out of Los Angeles and attempts catching fairing halves from launches out of VAFB.  Next attempt will be on the upcoming Iridium 7 launch.

This is an actual headline on CNN:
       SpaceX loses multi million dollar fairing

The headline doesn't mention that the launch and primary mission were successful, nor does it mention that SpaceX landed the first stage in the worst conditions ever.  Nope, the headline is about how SpaceX FAILED to catch the fairing.

Wow, are we disappointed in SpaceX for failing to do something that has NEVER been done by anyone before.

just saw the CNN story it was in my view not that negative I guess mileage might vary

Negative is one thing. Factually incorrect is much another.