Falcon Heavy Flight #2 - Arabsat 6A - LC-39A

[SMAlset]

SpaceX website for this goes live in just over 2 Hours now (8pm EST, 5pm PST). Waiting in the background on my laptop! Bad timing for a lot of people getting off work and driving home.

 

[Unpilot]

Launch window is Now 7pm EST

 

[mongo]

Launch window is Now 7pm EST

where are seeing that? SpaceX twitter feed said 8 two hours ago...

 

[Unpilot]

 

[808?]

Pushed another 4 hours now (HK time).

 

[Grendal]

8:32 PM EST

 

[Joe F]

Sitting here all day, and the only exciting thing was a few dolphins swam by.

 

[scaesare]

My feed shows "Live at 11:32PM" and I'm on the East coast... which is exactly 3 hours after the end of the launch window at 8:32PM... so I wonder if the stream is referencing West Coast time?

 

[Joe F]

I think that time on the feed is bogus. They’re pushing it right to the end of the window at 8:32.

 

[miimura]

I think that time on the feed is bogus. They’re pushing it right to the end of the window at 8:32.

Then why does it say "Live in 4 hours"??? The end of the window is coming up in an hour and 20 minutes.

 

[Joe F]

Then why does it say "Live in 4 hours"??? The end of the window is coming up in an hour and 20 minutes.

Bad web management???

Announcement at FTH cited upper level winds a concern, and launch window is now 8:32. Read, launch off for today a strong possibility.

 

[NoirMS]

Then why does it say "Live in 4 hours"??? The end of the window is coming up in an hour and 20 minutes.

 

[Pricee2]

I think it is because the "Live in 4 hours" post was several hours ago.

 

[Grendal]

Scrub! Darn it. See you tomorrow. Same time frame.

 

[Joe F]

Scrubbed.

 

[ecarfan]

Scrub! Darn it. See you tomorrow. Same time frame.

So reason for scrub is unfavorable high altitude winds?

 

[ecarfan]

Informative discussion of how wind shear effects rockets at What factors affect the ability of a rocket to sustain high-altitude wind shear? : spacex

 

[SMAlset]

SpaceX feed window now says Live in 25 hours (April 11, 6:35pm). I wish they would post EST next to the time.

 

[MacGreiner]

Sadly a no go. Jetty park was packed. Tomorrow will be my last shot. Next trip down will be STP-2.

 

[e-FTW]

Informative discussion of how wind shear effects rockets at What factors affect the ability of a rocket to sustain high-altitude wind shear? : spacex

Yes, quite informative! I recommend reading all of the “green” posts after your get past the Shuttle discussion. Including the one from Tory Bruno from ULA.

The tl;dr post for me was this one:

Remember wind shear is not wind speed. It's the difference in wind speed between the top and bottom of the rocket.

What that difference does is turn the rocket. The rocket corrects with an opposing torque by vectoring its engines.

However, in the brief time before this correction is accomplished, the rocket is flying slightly sideways.

Around max-Q, the pressure of the wind on the rocket is very significant. ISTR (someone correct me!) for a Falcon 9 it's around 1 atmosphere, or 14 psi.

A large rocket times a very small angle is a lot of square inches and many tons of additional aerodynamic pressure. Also, there's the torque from the engines that needs to be transmitted along the body of the rocket.

These are additional wonky loads on a rocket structure that's aggressively optimized for weight.

The solution is to either make the rocket stiffer (more weight, boo!), or limit launches to days of low wind shear.