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:

 

[Grendal]

Scott Manley's take on it.

 

[ecarfan]

Awe yeah!

https://twitter.com/x/status/1649523985837686784

I admire Elon’s optimism! But I will be stunned if there is another test flight in 2 months, or even in 3.

 

[Electroman]

Awe yeah!

https://twitter.com/x/status/1649523985837686784

“Massive water cooled Steel Plate”, meaning no flame trench.

I can see how a steel plate can avoid debris. But still a hot exhaust blow back has the potential to cause damage to the under part of the booster and the engines.

Why the resistance to build a trench? One time expense but probably worth it.

 

[ecarfan]

Scott Manley's take on it.

Just watched that before you posted It. Good analysis as always from Scott. He does state that a SpaceX source confirms the speculated HPU failure, even though as I posted upthread two NSF forum members have stated their SpaceX sources deny any HPU failure.

Scott included in his video this “leaked” image (it was not in the SpaceX webcast) of the vehicle shortly before destruction. Note how the vehicle is bent at the interstage area during the tumbling, not surprising given the the booster tanks were almost empty and the ship tanks were full, creating a massive imbalance between the two ends of the vehicle as it rotated!

Note that in the tiled area visible, only a few tiles are missing. That’s a hopeful sign.

 

[ecarfan]

Why the resistance to build a trench?

The water table at Boca Chica is very high; it’s a tideland. So a difficult project and yes, expensive.

 

[Electroman]

I guess the OLM legs also have to be steel plated.

 

[mongo]

“Massive water cooled Steel Plate”, meaning no flame trench.

I can see how a steel plate can avoid debris. But still a hot exhaust blow back has the potential to cause damage to the under part of the booster and the engines.

Why the resistance to build a trench? One time expense but probably worth it.

I'm thinking that, other that some standing wave effect, nothing is swimming upstream against that exhaust flow. Engine section is built to handle reentry without a burn.

Flame trench needs more depth, exit room, and water handling. All things in short supply at Starbase.

I guess the OLM legs also have to be steel plated.

They are. Well, at least above the old ground level.

 

[bxr140]

Bull feathers

Nope.

Where once there were joking remarks about a rocket blowing up, there are now bulleted list of successes.
A typical reporter doing research is not going to associate the former with actual success criteria.

 

[JB47394]

That's not uncommon, actually. Big motors need time to come up to a relatively steady state operation...things like transients in engine temperatures and pump pressures and combustion flame fronts, etc need to ~settle out before you want to release the vehicle....and there's an additional element of most rockets using this phase as the equivalent of what we think of with F9's 'static fire', so that takes a little bit of time too. (One could imagine this concept is baked into the Booster timeline)

I don't believe this is the case. If you watch the test firings of Raptors, they just light up and are stable in a split second. As I understand things, there is an eight second delay because of staggered starts of the 33 engines. So stuff like combustion fronts and such are probably at play, but only for the rocket as a whole, not the individual engines.

 

[Grendal]

Was any of the Charity Bets criteria met?

 

[Pricee2]

Water cooled steel plate below the orbital mount seems like a possible remedy to me. I have no expertise in this field but if the steel plate was dome shaped it seems that less energy would reflect back towards the base of the rocket.

 

[EVCollies]

Was any of the Charity Bets criteria met?

Yes, I did not win.

 

[ecarfan]

Water cooled steel plate below the orbital mount seems like a possible remedy to me. I have no expertise in this field but if the steel plate was dome shaped it seems that less energy would reflect back towards the base of the rocket.

SpaceX is on it. This tweet earlier today from Elon was posted upthread.

https://twitter.com/x/status/1649523985837686784

 

[bxr140]

I don't believe this is the case. If you watch the test firings of Raptors, they just light up and are stable in a split second.

Sure it is.

To be clear I don't contest raptor startup is 6-8 seconds, but for sure go/nogo criteria on a motor does not include "looks stable to me". There's plenty of motor level things that need to be stabilized [enough] and then as I noted once you get up to the rocket level and have 33 of them, it compounds things (and thus time).

Water cooled steel plate below the orbital mount seems like a possible remedy to me. I have no expertise in this field but if the steel plate was dome shaped it seems that less energy would reflect back towards the base of the rocket.

Likely.

Watercooled diverters are pretty common for Big Fire rockets; most have been deluge cooled. IIRC the NG diverter at LC-36 actually has internal passages (though I also recall it being deluged). Steel is typically used because it ablates pretty slow and predictably and can be pretty easily repaired by swapping out panels.

If SX maintains the OLM concept without a traditional @Electroman flame trench, I'd expect a concave conical diverter in the middle directing exhaust radially in ~all directions (maybe around the OLM legs a bit and less toward the tower?) and then maybe even secondary deflectors a la old school 39A. Ariane-like tunnels might also be a clever solution.

 

[Electroman]

Was any of the Charity Bets criteria met?

I would like to think I won.. but ..

 

[Electroman]

If SX maintains the OLM concept without a traditional @Electroman flame trench

I would love it, if they build one and name it after me..

 

[Matias]

Is there any acronym dictionary?
OLM= ?
HPU = hydraulic power unit?

 

[arnolddeleon]

Is there any acronym dictionary?
OLM= ?
HPU = hydraulic power unit?

Orbital Launch Mount

 

[HVM]

This is why hw4 is still closed:

https://twitter.com/x/status/1649497824457904129

The Kzinti Lesson works fine even with chemical rockets, if rocket is big enough.
(Ok, this is probable just sand and pieces of the wall, and asphalt is fine under that rubble.)

 

[NewbyMaybe]

Back pressure issue? The ignition blast created a crater large enough to reduce thrust? The engine failure/damage reduced thrust.
Reduced thrust resulted in altitude too low to trigger separation but the timing was correct to trigger flip?
Cascading faults but massive quantities of data so SpaceX wins again.