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]

Just posted by SpaceX. I think the image of the engines at liftoff came from the camera that took this video. Pretty awesome to watch in slo-mo!

https://twitter.com/x/status/1649172873494556679

 

[Pricee2]

After watching some of the various videos of the launch my theory (NSWAGs) is that multiple engines were damaged by flying debris on lift off. In some of the videos large splashes can be seen in the ocean and in the inland estuaries. Significant chunks were probably bouncing off the inside of the launch mount and into the engine cluster.

 

[ecarfan]

On the NSF forum, @Corvus Corax posted (bottom of that page) that their contact at SpaceX said that the booster did not lose hydraulic power, the loss of control occurred because during the stage separation “flip maneuver” the stages did not separate, for unknown reasons. Read the post and the followup posts on the next page. Another NSF frequent poster, @Herb Schaltegger, says their contact stated “essentially the same”.

And that information in fact supports a comment that John Insprucker made; just when the vehicle started to rotate he said excitedly “the flip is underway!”. At the time that made no sense to me. Stage sep had not occurred; what “flip” was he talking about? But John seemed to have been anticipating the vehicle’s change in attitude, and welcomed it. Then, when no stage sep occurred he grew silent for several seconds.

 

[Grendal]

Here's an important statement from a Starship customer:
(pulled from the Eric Berger article)
"Every great achievement throughout history has demanded some level of calculated risk because with great risk comes great reward," NASA Administrator Bill Nelson said in a statement after the test flight. "Looking forward to all that SpaceX learns, to the next flight test—and beyond."

 

[Electroman]

Why would Starship go to a different totally unproven flip maneuver for stage separation?. What is wrong with the tried and proven standard separation method? The whole idea of separation by flipping and thru angular momentum seem very convoluted to me. Why change the attitude of the Starship? Seems like a solution looking for a problem.

 

[Buckminster]

Watch from 3 mins to 4:30:

Starship is supposed to be 5 times heavier than booster during manoeuvre. I assume it wasn't due to loss of engines.

 

[HVM]

On the NSF forum, @Corvus Corax posted (bottom of that page) that their contact at SpaceX said that the booster did not lose hydraulic power, the loss of control occurred because during the stage separation “flip maneuver” the stages did not separate, for unknown reasons. Read the post and the followup posts on the next page. Another NSF frequent poster, @Herb Schaltegger, says their contact stated “essentially the same”...

That can't be true, stage sep can only happen after MECO for obvious reason. Majority of Raptors were on to the termination.

 

[mongo]

Why would Starship go to a different totally unproven flip maneuver for stage separation?. What is wrong with the tried and proven standard separation method? The whole idea of separation by flipping and thru angular momentum seem very convoluted to me. Why change the attitude of the Starship? Seems like a solution looking for a problem.

Starlink has proven out flip release.
SpaceX's current F9/FH approach is a push stick up the bell of the single mVac engine. Starship is roughly 11 times the mass vs a F9 second stage, so that may not scale well. Plus, it requires extra parts and interstage volume available is practically non-existent.
F9:
Prop: 93 mt
Dry: 4 mt (including fairing?)
Payload: 23 mt
Total: 120 mt

Starship:
Prop: 1,200 mt
Ship: 85 mt
Payload: 100 mt
Total: 1,385 mt

 

[mongo]

On the NSF forum, @Corvus Corax posted (bottom of that page) that their contact at SpaceX said that the booster did not lose hydraulic power, the loss of control occurred because during the stage separation “flip maneuver” the stages did not separate, for unknown reasons. Read the post and the followup posts on the next page. Another NSF frequent poster, @Herb Schaltegger, says their contact stated “essentially the same”.

And that information in fact supports a comment that John Insprucker made; just when the vehicle started to rotate he said excitedly “the flip is underway!”. At the time that made no sense to me. Stage sep had not occurred; what “flip” was he talking about? But John seemed to have been anticipating the vehicle’s change in attitude, and welcomed it. Then, when no stage sep occurred he grew silent for several seconds.

I think John was speaking based on expected timeline. Remember the non-launch "lift off!" mission (not John)? If he wasn't paying attention to altitude, he would realize things were off nominal.

Stack was not at an altitude where separation should trigger. Unless it was also time based, which make little to no sense, at least to me.

 

[ecarfan]

Watch from 3 mins to 4:30:

Starship is supposed to be 5 times heavier than booster during manoeuvre. I assume it wasn't due to loss of engines.

Thanks. I’m still trying to understand this new stage separation technique.

That video states that before MECO, the booster engines gimbal to impart spin to the vehicle along the long axis (adding angular momentum) and also change pitch and that causes stage sep. Do I have that right? A reference is made to this being similar to how the F9 second stage causes Starlink sats to deploy, I assume by using the RCS thrusters?

I rewatched the test flight video, multiple times. Here is what Insprucker said:

T+01:43 “100 seconds into flight“ (What? Is the displayed clock and telemetry that far out of synch?)
T+01:49 “Our next major activity is going to be shutdown of the first stage”
T+01:55 “With shutdown we will get separation of Starship from Super Heavy and ignition of the Starship engines When Starship separates it will light up six engines in a staggered sequence and if all goes well those six engines will burn for almost six and a half minutes.”
T+02:19 “Onboard view from Starship, and there’s views of the Raptor engines on the second stage as we prepare for stage separation.”
T+02:24 “Now after stage separation the first stage will flip and we will begin a boostback maneuver for landing in the Gulf”

As he said that the vehicle was noticeably changing pitch (?) and the crowd grew quiet.

So the SpaceX stated timeline of test flight events, and Insprucker’s own words show that MECO was planned to occur before stage sep.

T+02:29 (Vehicle speed peaks at 2157kph and then steadily decreases, though engines still appear to be running, vehicle is rotating)
T+02:41 “Continuing to fly at two minutes forty seconds as we get ready for main engine cutoff”
T+02:49 “Beginning the flip for stage separation.”

It’s hard for me to tell when or even if MECO occurred, but at this point the vehicle seemed out of control to my admittedly non-expert eye. John stopped talking, there was no commentary for several seconds, and then Kate said “As of now we are awaiting stage separation…” but it seemed obvious that even if that occurred the vehicle was in a spin.

So I remain unclear on what the plan was for stage sep. Here is the SpaceX timeline for the booster (The test flight timeline has been removed from the SpaceX website).

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

 

[ecarfan]

On another topic; the diagram at the lower right showing which engines were running and which were not appeared to undercount the number of operating engines. For example, at this point in the flight the diagram showed 5 engines out but clearly there were 6. Telemetry error?

 

[Electroman]

Unless it was also time based, which make little to no sense, at least to me.

Not withstanding the fact that 6 boosters were out I think even the rest of the Raptors underperformed, leaving the rocket at less than half the height and perhaps at half the velocity of where it should be at that time.

Wondering if SpaceX has some fundamental problem in their hand requiring radical redesign. Perhaps the stack is a bit too big, too heavy for the 33 Raptors. And then they have the problem of stage separation..

 

[mongo]

Thanks. I’m still trying to understand this new stage separation technique.

That video states that before MECO, the booster engines gimbal to impart spin to the vehicle along the long axis (adding angular momentum) and also change pitch and that causes stage sep. Do I have that right? A reference is made to this being similar to how the F9 second stage causes Starlink sats to deploy, I assume by using the RCS thrusters?

I rewatched the test flight video, multiple times. Here is what Insprucker said:

T+01:49 “Our next major activity is going to be shutdown of the first stage”
T+01:55 “With shutdown we will get separation of Starship from Super Heavy and ignition of the Starship engines.”
T+02:19 “Onboard view from Starship, and there is views of the Raptor engines on the second stage as we prepare for stage separation.”
T+02:24 “After stage separation the first stage will flip and we will begin a boostback maneuver for landing in the Gulf”

As he said that the vehicle was noticeably changing pitch (?) and the crowd grew quiet.

So the SpaceX stated timeline of test flight events, and Insprucker’s own words show that MECO was planned to occur before stage sep.

T+02:41 “Continuing to fly at two minutes forty seconds as we get ready for main engine cutoff”
T+02:49 “Beginning the flip for stage separation.”

At this point MECO had not occurred And the vehicle seemed out of control to my admittedly non-expert eye. John stopped talking, there was no commentary for several seconds, and then Kate said “As of now we are awaiting stage separation…” but it seemed obvious that even if that occurred the vehicle was in a spin.

So I remain unclear on what the plan was for stage sep. Here is the SpaceX timeline for the booster (The test flight timeline has been removed from the SpaceX website).

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

Not withstanding the fact that 6 boosters were out I think even the rest of the Raptors underperformed, leaving the rocket at less than half the height and perhaps at half the velocity.

Wondering if SpaceX has some fundamental problem in their hand requiring radical redesign. Perhaps the stack is a bit too big, too heavy for the 33 Raptors. And then they have the problem of stage separation..

Yeah, I just rewatched to log the velocity and altitude data. Crunching those numbers now. We know this stack is less optimized (heavier) than the next version.

Based on timing of events, it seems like some of the systems may have been going for stage separation and part weren't. This could be due to differing criteria for the systems (which isn't great from an overall flight management software point of view).
Example:
Clamp release arms after 60km altitude
Booster performs maneuver at 2:40
MECO at X velocity and Y altitude

Ideally, they reach their altitude and velocity targets, cut all but one or two engines, kick stack into a spin, cut engines, release clamps, and they separate.

Key attribute of the maneuver is that the center of mass/ rotation is near or within Starship so booster departs tangentially.

 

[ecarfan]

Ideally, they reach their altitude and velocity targets, cut all but one or two engines, kick stack into a spin, cut engines, release clamps, and they separate.

Thanks. By “kick stack into a spin”, spin on which axis? Radial, longitudinal, both?

 

[mongo]

Thanks. By “kick stack into a spin”, spin on which axis?

Good question, I'd guess pitch vs yaw (definitely not roll ). Stack already has a pitch up attitude, it's interesting to consider the relative aero drag vs mass of the two stages, would this be an instance of "I'll hit the brakes and he'll fly right by?".

From my preliminary data analysis, it looks like two engine outs clearly show up in the acceleration profile. Velocity plot is very stable. Climb rate is definitely sluggish which makes sense with the early loss of 3-5 engines. At 1.5 TWR @ 100% thrust, 22 engines worth of thrust goes to offset gravity. At 90% thrust, it takes 24.5 leaving 8.5 for acceleration. So it basically lost half it's net force.

Seems loke maybe the flight computer prioritizes velocity over altitude which would result in increased aero losses. Interesting problem, what is the best control method with critical or insufficient thurst?

 

[ecarfan]

Road to the launch site remains closed until 2PM CDT today. I wonder why they are waiting so long? Are there damaged GSE tanks that have not fully vented?

 

[ecarfan]

New image from RGV showing pad damage. Wow. And that’s only part of the damaged area.

 

[tivoboy]

Road to the launch site remains closed until 2PM CDT today. I wonder why they are waiting so long? Are there damaged GSE tanks that have not fully vented?

View attachment 930521

I think it can take DAYS if not WEEKS to actually clean up all the debris..

 

[mongo]

New image from RGV showing pad damage. Wow. And that’s only part of the damaged area.

View attachment 930522

Sure, but that's just concrete, easy to repour. My question is, what did it then land on? And how much of that chunk stayed intact?

 

[ecarfan]

Love Chris Hadfield. His analysis is spot on.