SpaceX Starship - Orbital Test Flight - Starbase TX

Launch Date: April 20
Launch Window: 8:28am CDT (6:28am PDT, 13:28 UTC) - 62 minute window
Launch site: LC-1? - Starbase, Boca Chica Beach, Texas
Core Booster Recovery: Expended in Gulf
Starship Recovery: Water landing near Hawaii
Booster: Super Heavy Booster 7
Starship: Starship 24
Mass: No mass simulator mentioned
Orbit: LEO-ish
Yearly Launch Number: 26

A SpaceX Super Heavy and Starship launch vehicle will launch on its first orbital test flight. The mission will attempt to travel around the world for nearly one full orbit, resulting in a re-entry and splashdown of the Starship near Hawaii.

Webcast:

 

[ecarfan]

S24 was unstacked (temporarily, I assume) sometime last night for “final launch preps”.

 

[mongo]

New video from NSF covering the latest info SpaceX released about the test flight. Most of what the video covered won’t be news to those on this thread, but there were a couple of things I noted:

1) Elon told this to Tim Dodd two years ago but I had forgotten; For SH/Starship there is no “pusher” stage separation mechanism, instead there are three “latches” that will be released and then “conservation of angular momentum” will “separate the stages” in the same manner as payloads are released from an F9 second stage adaptor (I hope I am understanding this correctly).

2) NSF expects all 6 Starship engines to be ignited once stage sep has occurred, based on the Starship engine burn time specified.

3) No mention by the NSF narrator of what I considered to be an error in the SpaceX test flight diagram; the booster orientation shown during the boostback burn. It’s hard to believe that NSF didn’t notice the booster orientation shown at that point: is the diagram actually correct? The NSF Forum thread on the test flight makes no mention of it. Perhaps I am wrong; my spouse noted it would not be the first time.

1) I'm sure they did the numbers, but the thought of Starship hanging off Super Heavy in a more horizontal orientation held only by those three latches weirds me out. (Really, it's held in place by acceleration, aero resistance, resulting friction, and the latch shear strength)

3) yeah, graphics messed those up. Desktop version is worse than mobile.

 

[mongo]

Maybe today for license

https://twitter.com/x/status/1646484466481651715

 

[JSNH1919]

Maybe today for license

https://twitter.com/x/status/1646484466481651715

Anyone traveling down to see the launch?
I am. I even rented a Tesla.
Meetup at Margaritaville?

 

[mongo]

Flight road closure 17th
https://www.cameroncountytx.gov/wp-...TO-TEMP.-BEACH-CLOSURE-AND-HWY.04.17.2023.pdf

https://twitter.com/x/status/1646595466803687426

 

[ecarfan]

NSF says that S24 was destacked for arming the FTS.

 

[ecarfan]

(EDIT: oops, @mongo beat me to it!)

Amended Order Closing Boca Chica Beach and State Hwy 4; April 17, 2023 with alternative date of April 18, 2023 or April 19, 2023 - Cameron County

Scheduled Road Closure, SpaceX

www.cameroncountytx.gov

Road closures updated to flight closures.

"Subject to approval of a flight activity license by FAA if the closure is to be used for a launch."

April 17th-19th, 12AM to 2PM local time.

 

[ecarfan]

SpaceX graphic for the test flight has been changed, the booster pointing the wrong direction has been moved. However the new graphic is still confusing to me; it shows the orientation during the boostback burn but does not show the path the booster will take to get the engine end pointing down for descent.

 

[Electroman]

It starts going east and then after MECO flips and goes west. So far so good. But why would it again end up going east? Doesn’t make sense

 

[ecarfan]

What a static diagram like that can’t convey is the dynamic trajectory of the vehicles. At stage sep the booster doesn’t just stop and flip; the flip happens as it continues to go eastward (in this case). The burn serves to slow down that eastward trajectory so that it lands in the Gulf and not out in the Atlantic. The booster never actually “goes west”.

 

[Electroman]

What a static diagram like that can’t convey is the dynamic trajectory of the vehicles. At stage sep the booster doesn’t just stop and flip; the flip happens as it continues to go eastward (in this case). The burn serves to slow down that eastward trajectory so that it lands in the Gulf and not out in the Atlantic. The booster never actually “goes west”.

Agreed. That is why nothing makes sense in that diagram.

 

[JohnnyEnglish]

What a static diagram like that can’t convey is the dynamic trajectory of the vehicles. At stage sep the booster doesn’t just stop and flip; the flip happens as it continues to go eastward (in this case). The burn serves to slow down that eastward trajectory so that it lands in the Gulf and not out in the Atlantic. The booster never actually “goes west”.

For RTLS the boostback burn does reverse the booster's direction of travel, otherwise how would it get back to the launch site? I assume that SpaceX will be trying to make the test flight as close to an RTLS profile as they think is safe (hence the landing in the Gulf) in order to provide data that best fits their target mode of operation.

 

[mongo]

If they made things somewhat scaled, it would be illegible. As it is, booster would not be pointing downward while firing (most likely) and return path is all westward.
Super Heavy will do mostly the same things as an F9 booster

*Fast* flip turn at (with?) separation
Boostback burn (firing while pointing west) to reverse horizontal velocity for 55 seconds
Continues rising while RTLS and does a *slow* spin to an engine first orientation
Back through atmosphere *no* re-entry burn
Descend
Kick on engines at last minute, *literally*, engines fire for only 23 seconds. Transonic to stopped is 31 seconds, >1 G deceleration.
Bloop

00:00:55	Max Q (Moment of Peak Mechanical Stress on the Rocket)
00:02:49	Booster Main Engine Cutoff
00:02:52	Stage Separation
00:02:57	Starship Ignition
00:03:11	Booster Boostback Burn Startup
00:04:06	Booster Boostback Burn Shutdown
00:07:32	Booster is Transonic
00:07:40	Booster Landing Burn Startup
00:08:03	Booster Landing Burn Shutdown

 

[mongo]

TFR for the 17th
3/1793 NOTAM Details

 

[ecarfan]

For RTLS the boostback burn does reverse the booster's direction of travel, otherwise how would it get back to the launch site?

For this Starship test flight the booster does not do an RTLS profile (of course it will in the future, that is the plan, to land at Stage Zero). My attempt at describing the part of the booster, to answer the question posed by @Electroman, said that the overall path of the booster was eastward over the Gulf. It does not go west even though it does flip around an “point” westwards.

Sorry for any confusion.

 

[ecarfan]

What a static diagram like that can’t convey is the dynamic trajectory of the vehicles. At stage sep the booster doesn’t just stop and flip; the flip happens as it continues to go eastward (in this case). The burn serves to slow down that eastward trajectory so that it lands in the Gulf and not out in the Atlantic. The booster never actually “goes west”.

And I may in fact be wrong. An amazing graphic has been posted at:

https://twitter.com/x/status/1646701133803520000

 

[ecarfan]

S24 remains unstacked, resting on the transporter stand. No FAA launch license yet. Hopefully it will be issued today.

https://twitter.com/x/status/1646833617669177346

 

[mongo]

NOTAM "Navigational hazards from rocket launching activity may include, free falling debris and/or descending vehicles or vehicle components, under various means of control."

https://twitter.com/x/status/1646938322189557760

 

[HVM]

https://twitter.com/x/status/1646994586768756736

Green light go: SpaceX receives a launch license from the FAA for Starship

"So far they’ve done what they need to do with regard to environmental impact."

arstechnica.com

Green light go: SpaceX receives a launch license from the FAA for Starship​

 

[HVM]

https://twitter.com/x/status/1646996041978507264