SpaceX Falcon 9 - EchoStar 23 - March 16, 2017 - DISCUSSION

[manoweb]

Also going to be one of the colder launches, with temperatures predicted to be around 42F at the time of T-0 and dropping throughout the window.

Many times in automotive races, colder weather means more power as intake air is denser. In a rocket however, colder weather makes it worse? Is this going to be colder than the last V1.1 launch in Jan 2016 from Vandenberg (where apparently ice did not allow the legs to lock in place once landed (yes I know this launch won't try a landing))

[WmThomas]

Maybe they just need more LOX ready than on typical launches because it's such a long window, so could potentially have more recycles than normal.

I'm no expert, but I think you are confusing normal, near-boiling-point LOX with the super cooled LOX SpaceX is now using. As super-cooled warms, it doesn't boil off: it just expands. They could drain it, perhaps, but they couldn't maintain the same mass of LOX over time.

Normal, boiling-point LOX can be boiled off and replaced the way you described. Not so super-cooled.

Cooler air temperatures will widen their effective window, though.

[ZachS09]

Why have a long launch window if the supercold LOX warms up over time, causing the thrust level to decrease?

They should make the windows instantaneous specifically for F9 Full Thrust and any launch vehicle that uses supercold densified propellant.

[Req]

Draining and refilling is exactly what they have been doing since subcooling became the norm.  This is old and well-known/discussed information, along with how it decreases the number of opportunities in any given window.  And why they could potentially need more LOX than usual in a window that allows more of these recycles than normal.

[pstephens]

Why have a long launch window if the supercold LOX warms up over time, causing the thrust level to decrease?

One reason is to delay prop load until later in the window if the beginning of the window is going to have a problem. A weather issue may blow over, for example.

I believe once they've initiated prop load their launch window is narrowed considerably.

[Jim]

Why have a long launch window if the supercold LOX warms up over time, causing the thrust level to decrease?

One reason is to delay prop load until later in the window if the beginning of the window is going to have a problem. A weather issue may blow over, for example.

I believe once they've initiated prop load their launch window is narrowed considerably.

10 to 20 minutes would be a good guess.   Depends on the bulk temp of the loaded LOX and the outside temp.

[Lars-J]

Sweet image from SpaceX:

The RCS pods appear to be present on the interstage, but they could be plugged/inert.

EDIT: And did someone forget their car at the launch pad?  That would be an interesting insurance call...     (probably gone by now)

[Flying Beaver]

Sweet image from SpaceX:

The RCS pods appear to be present on the interstage, but they could be plugged/inert.

EDIT: And did someone forget their car at the launch pad?  That would be an interesting insurance call...     (probably gone by now)

This core (30) was seen at McGregor with all the landing 'bits'. So yes you can see everything has either been taken out or plugged.

(look close at the base in other pics and you can see the landing leg wiring).

[Steven Pietrobon]

EDIT: And did someone forget their car at the launch pad?  That would be an interesting insurance call...     (probably gone by now)

That might be the photographer's car.

[old_sellsword]

Sweet image from SpaceX:

The RCS pods appear to be present on the interstage, but they could be plugged/inert.

EDIT: And did someone forget their car at the launch pad?  That would be an interesting insurance call...     (probably gone by now)

This core (30) was seen at McGregor with all the landing 'bits'. So yes you can see everything has either been taken out or plugged.

(look close at the base in other pics and you can see the landing leg wiring).

I think the only thing they changed was to remove the entire grid fin assembly (stowing latches and all). They left most (if not all) of the landing leg wiring as you noted, and the RCS thruster blocks are still present; neither of those two things will be on future expendable cores.

[Lars-J]

I just noticed that the TE blue actuators don't really look like hydraulic actuators at all. Are they mechanical with a track in the center? Interesting. They look quite different than the 'Vandy' TE actuators. (see pic)

[dmc6960]

Just made it to my viewing point in Titusville. Much more cars here than previous attempt.

[old_sellsword]

No technical webcast tonight? Only the hosted webcast is working now.

SpaceX employee (works with the webcasts) Bencredible says this is supposed to happen.

https://www.reddit.com/r/spacex/comments/5z8dkm/welcome_to_the_rspacex_echostar23_official_launch/dezsgng/

FYI - I need to start the technical webcast 10 minutes after the hosted so you will only get 2 minutes of SpaceX FM on technical.

[sewebster]

They just showed a shot on the hosted webcast of the vehicle going up the ramp with the payload "pointing down", i.e. not using the TEL to keep it level...

[mvpel]

I just noticed that the TE blue actuators don't really look like hydraulic actuators at all. Are they mechanical with a track in the center? Interesting. They look quite different than the 'Vandy' TE actuators. (see pic)

Protective covers.

https://i.stack.imgur.com/Xpl61.jpg

[Orbiter]

Just came back inside, freezing cold. Tracked the launch in my telescope. Anyone notice the plume being lit up by the moonlight? Really provided quite a site.

[Pete]

Quite the difference in speed at MECO.  9500 km/h, vs the about 6000km/h when in reusable configuration.

[MarekCyzio]

View from my neighborhood

[RotoSequence]

That last sliver of Stage 1's trajectory hasn't moved in a while. Point where they lost tracking/signal from Stage 1?

[dmc6960]

Very nice. I have now seen a shuttle launch up close, Falcon 9 launch up close, and Delta IV launch from afar (Orlando). Will do again.