SpaceX Starship : First Flight : Starbase, TX : 20 April 2023 - DISCUSSION

[kevinof]

I think until we see it or don’t on the day no one can say right now. It makes sense they don’t want to clutter the conversation about ‘crash it into the water’ with lingo about landing it. Best to keep the plan simple ‘we’re gonna lose it’ and then do the flip anyway. I doubt how you crash it into the water in the last 500m makes any difference to launch licences.

Very sensible post there but this is NSF and wild speculation is just another day on this site

[MichaelBlackbourn]

Maybe it's a safety issue.  If it were to survive the landing, there might be some residual fuel in the tanks, leaving recovery team members exposed to a potential bobbing bomb.

Just thinking out load.

Then the navy gets target practice. It’s happened before.

[jstrotha0975]

Maybe it's a safety issue.  If it were to survive the landing, there might be some residual fuel in the tanks, leaving recovery team members exposed to a potential bobbing bomb.

Just thinking out load.

Then the navy gets target practice. It’s happened before.

The Navy would most likely use divers with explosives if they get involved.

[MichaelBlackbourn]

Maybe it's a safety issue.  If it were to survive the landing, there might be some residual fuel in the tanks, leaving recovery team members exposed to a potential bobbing bomb.

Just thinking out load.

Then the navy gets target practice. It’s happened before.

The Navy would most likely use divers with explosives if they get involved.

It was an Air Force air strike last time. So probably not divers.

https://www.thedrive.com/the-war-zone/18343/did-the-u-s-air-force-bomb-a-rogue-spacex-booster-rocket

[sferrin]

So...any word on the FAA license? 

[Lee Jay]

So...any word on the FAA license? 

Soon.

[Cheapchips]

Do we think that the booster's 'water landing' will be a simulated tower landing?

If it comes to rest at catch arm height and then cuts it's engines, it'll fall 40m?  Presumably that's enough of a fall to produce a violent end.

[WisRich]

Do we think that the booster's 'water landing' will be a simulated tower landing?

If it comes to rest at catch arm height and then cuts it's engines, it'll fall 40m?  Presumably that's enough of a fall to produce a violent end.

Interestingly, I was reading the test launch summary from SpaceX and in regards to the tower it says:

 "...the launch and catch tower is designed to support vehicle integration, launch, and catch of the Super heavy rocket booster. For the first flight, the team will not attempt a vertical landing of Starship or catch of the Super Heavy Booster.."

I thought Starship was to be caught by the tower. This passage indicates otherwise.  I guess I overlooked that small detail.

[KilroySmith]

I thought Starship was to be caught by the tower. This passage indicates otherwise.  I guess I overlooked that small detail.

Well, Starship is going to be landing south of Hawaii, and the Tower is in Texas, so unless they extend the chopsticks dramatically the tower ain't gonna be catching Starship this flight.

By next year at this time, I expect to have seen both Booster and Starship landings. But neither one is going to happen this month.  Hopefully there'll be video of the Booster attempting a water landing, but I'm not expecting to see much in the way of video of the Starship impacting other than perhaps a long-distance shot from an airplane.

[JWC]

What if the current prototypes have negative payload?  A year of adding structural reinforcements eating up all the margins until they were forced to drop the landing fuel.  Without that fuel they now have margin to pull off this flight plan.

[Herb Schaltegger]

What if the current prototypes have negative payload?  A year of adding structural reinforcements eating up all the margins until they were forced to drop the landing fuel.  Without that fuel they now have margin to pull off this flight plan.

Starship should be able to loft 100 tons or more to orbit in a fully-reusable configuration. There is no way they have “negative margin” no matter how over-built Ship 24 and Booster 7 might be compared to later models.

[jon.amos]

Could it be as simple as they want belly flop into water data and this ship has no hope of recovery anyway?

[maquinsa]

I have little experience on real world engineering but I have done a lot of programming projects for my own and it is good practice to start testing only part of the code if you know there is even a high chance of not getting to run all of it on the first try anyway. Maybe they believe that adding the complexity of a landing to the flight plan when there is a high probability of not getting there isn’t worth the risk of messing up another part they haven’t researched as much

They are not going to recover it even if it gets to that point so why test something that has already been?

Edited

[mpusch]

It was an Air Force air strike last time. So probably not divers.
https://www.thedrive.com/the-war-zone/18343/did-the-u-s-air-force-bomb-a-rogue-spacex-booster-rocket

Not to go down this rabbit hole too far, but according to Spacex:

"While the Falcon 9 first stage for the GovSat-1 mission was expendable, it initially survived splashdown in the Atlantic Ocean. However, the stage broke apart before we could complete an unplanned recovery effort for this mission. Reports that the Air Force was involved in SpaceX's recovery efforts are categorically false."

[alugobi]

Perhaps the webcast will explain the landing plan.

[rsnellenberger]

The changes to the flight plan may be to eliminate some minor issues that SpaceX feels the FAA is still not satisfied with.

Nope, that's not it. When Gwynne took over some months ago SpaceX did a thorough review of this test flight. Since then a number of test objectives have been moved from this test flight to future ones.

But, why? Flip & landing was already demonstrated by SN15. What was wrong about leaving this maneuver in the flight plan?

I haven't seen it mentioned already, but S24 will be the last Ship that uses hydraulic gimbeling, so the whole "test like you fly" argument really doesn't apply as far as the flip maneuver goes.  The belly landing eliminates the need to make any particular effort to keep the hydraulic systems operational through the coast phase and re-entry, whereas the "elonerons" (sp?) will be operating off batteries as they will in future Ships.

[dodageka]

In the very beginning of the thread there was a discussion why, in the FCC application, SpaceX wrote of a “Booster touchdown” and a “Ship splashdown”. Back then some people thought that this might suggest an actual landing of a booster on a barge, but ist thought that SpaceX just didn’t pay close attention to their wording. That’s what I still believe as well, but in the light of the new information it makes you wonder whether SpaceX already back then decided against the bellyflop on the first flight

[uhuznaa]

What if the current prototypes have negative payload?  A year of adding structural reinforcements eating up all the margins until they were forced to drop the landing fuel.  Without that fuel they now have margin to pull off this flight plan.

I'm sure that their dry mass is higher than they wanted it to be right now, but negative payload would mean it would be higher by 100 or 150 tons. Not very probable.

What I could imagine is that they have thermal problems and that 90 minutes after launch and after reentry and hypersonic flight they know they would have some serious boil-off problems with the propellants in the nose tanks. This is something I always wondered about as soon as they moved their header tanks into the nose from within the main tanks for center of gravity reasons.

Well, or this is just some unlucky wording on their mission page. Just like the graphic that has the booster boost itself down instead of back...

Anyway, getting the ship far enough in one piece and in controlled descent to bellyflop into the water will be a huge success already.

[WisRich]

The changes to the flight plan may be to eliminate some minor issues that SpaceX feels the FAA is still not satisfied with.

Nope, that's not it. When Gwynne took over some months ago SpaceX did a thorough review of this test flight. Since then a number of test objectives have been moved from this test flight to future ones.

But, why? Flip & landing was already demonstrated by SN15. What was wrong about leaving this maneuver in the flight plan?

I haven't seen it mentioned already, but S24 will be the last Ship that uses hydraulic gimbeling, so the whole "test like you fly" argument really doesn't apply as far as the flip maneuver goes.  The belly landing eliminates the need to make any particular effort to keep the hydraulic systems operational through the coast phase and re-entry, whereas the "elonerons" (sp?) will be operating off batteries as they will in future Ships.

Wait, what? No more gimbling? Well that's interesting. I'm looking forward to seeing the new flip maneuver.

[EspenU]

Wait, what? No more gimbling? Well that's interesting. I'm looking forward to seeing the new flip maneuver.

No more hydraulic gimbaling. They will be using electric gimbal going forward.