Author Topic: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion  (Read 516891 times)

Offline meekGee

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #40 on: 02/15/2023 11:14 pm »

Switching to S26 would add months in preflight testing.  Maybe they do that, but at this point, just lob something into the atmosphere and clear the OLM for the next set.

Yes, and there are several posts that have mentioned S24 can only be flown on B7 because the following ships (S25 onward) are different enough and the following boosters (B9 and onward) are different enough that S24 with B9+ (and B7 with S25+) won't be a viable stack. I believe I remember these posts were well sourced.
Maybe the plan is that B7 flies 24, but B9 will nominally throw more than one ship?

That's insane (actual reuse as opposed to just retrieval) but they catch B9 and can inspect it, they can make the call then.

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Offline baking

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #41 on: 02/15/2023 11:28 pm »
So if Ship 26 is for the Tipping Point Demo it has to have at least an additional tank in the cargo area.

"Large-scale flight demonstration to transfer 10 metric tons of cryogenic propellant, specifically liquid oxygen, between tanks on a Starship vehicle. SpaceX will collaborate with Glenn and Marshall."

https://www.nasa.gov/directorates/spacetech/solicitations/tipping_points/2020_selections

(Presumably they wouldn't want to transfer liquid oxygen to the methane tanks.)

So Cryotesting and structural testing of the new tank structure is a must.  Therefore, if Ship 26 is a tanker prototype, it seems likely that it will never see flight and orbit.  Some later version could get the fins, flaps, and heatshield for reentry.  Why test only 2 of 3 phases if you have such a limited number of launches.  We all agree that the Starship factory can crank them out at whatever pace is needed.

The only way Ship 26 is getting to fly is if it is deadweight for an early orbital attempt because there is concern that the earlier Starship prototypes would not survive the ascent and risk forcing a flight termination of the booster..
« Last Edit: 02/15/2023 11:29 pm by baking »

Offline DanClemmensen

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #42 on: 02/15/2023 11:50 pm »
So if Ship 26 is for the Tipping Point Demo it has to have at least an additional tank in the cargo area.

"Large-scale flight demonstration to transfer 10 metric tons of cryogenic propellant, specifically liquid oxygen, between tanks on a Starship vehicle. SpaceX will collaborate with Glenn and Marshall."

https://www.nasa.gov/directorates/spacetech/solicitations/tipping_points/2020_selections

(Presumably they wouldn't want to transfer liquid oxygen to the methane tanks.)

So Cryotesting and structural testing of the new tank structure is a must.  Therefore, if Ship 26 is a tanker prototype, it seems likely that it will never see flight and orbit.  Some later version could get the fins, flaps, and heatshield for reentry.  Why test only 2 of 3 phases if you have such a limited number of launches.  We all agree that the Starship factory can crank them out at whatever pace is needed.

The only way Ship 26 is getting to fly is if it is deadweight for an early orbital attempt because there is concern that the earlier Starship prototypes would not survive the ascent and risk forcing a flight termination of the booster..
I think they need to do the cryo transfer test to validate cryo transfer before finalizing the Depot and Tanker designs.They may as well do it early, because they will get paid $53 million for it. I don't know if there is a tank in the payload area or if the payload area IS the tank.

Offline sferrin

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #43 on: 02/16/2023 12:38 am »
(Presumably they wouldn't want to transfer liquid oxygen to the methane tanks.)
Stupid question here.  If they didn't plan on bringing 26 back anyway, and both methane and O2 being cryogenic, would venting one of them to space in a controlled manner clean it up enough to minimize the risk of explosion when pumping the other propellant into the now empty tank?
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Offline robot_enthusiast

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #44 on: 02/16/2023 12:38 am »
So if Ship 26 is for the Tipping Point Demo it has to have at least an additional tank in the cargo area.

"Large-scale flight demonstration to transfer 10 metric tons of cryogenic propellant, specifically liquid oxygen, between tanks on a Starship vehicle. SpaceX will collaborate with Glenn and Marshall."

https://www.nasa.gov/directorates/spacetech/solicitations/tipping_points/2020_selections

(Presumably they wouldn't want to transfer liquid oxygen to the methane tanks.)

So Cryotesting and structural testing of the new tank structure is a must.  Therefore, if Ship 26 is a tanker prototype, it seems likely that it will never see flight and orbit.  Some later version could get the fins, flaps, and heatshield for reentry.  Why test only 2 of 3 phases if you have such a limited number of launches.  We all agree that the Starship factory can crank them out at whatever pace is needed.

The only way Ship 26 is getting to fly is if it is deadweight for an early orbital attempt because there is concern that the earlier Starship prototypes would not survive the ascent and risk forcing a flight termination of the booster..
S26 is believed to have standard header tanks installed, which are large enough to accomplish the test and would not require any additional testing which would only be useful for a one off vehicle.

Online Oersted

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #45 on: 02/16/2023 03:48 pm »
I just now realise that when the first orbital flight is in the books we will be in for a smorgasbord of complex test flights to wring out the crinkles of the Starship system at an ever accelerating pace, and to thoroughly try out all its capabilities. It will be totally exhilarating to follow!

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #46 on: 02/16/2023 03:55 pm »
Only 5 flights/year from Boca Chica, so need to get to FL ASAP (maybe 3rd flight if first 2 are fairly successful?).  I think the ramp up is going to be fairly gradual, due to implementing lessons learned about launch support, mainly.
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Offline CorvusCorax

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #47 on: 02/16/2023 08:55 pm »
(Presumably they wouldn't want to transfer liquid oxygen to the methane tanks.)
Stupid question here.  If they didn't plan on bringing 26 back anyway, and both methane and O2 being cryogenic, would venting one of them to space in a controlled manner clean it up enough to minimize the risk of explosion when pumping the other propellant into the now empty tank?

Tricky, if you vent a tank completely the propellant starts boiling and cooling, until it turns to ice. You.might end up with methane ice in a vacuum insulated stainless steel thermos bottle.

When you then start tranfering  liquid oxygen xou have solid methane immersed in liquid oxygen.

Aka a very potent explosive.

You vould vent the liquids completely if you apply a) ullage thrust for settling and then b) use a pressurized ullage gas to blow it out, for example from Nitrogen COPVS

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #48 on: 02/16/2023 10:21 pm »
Only 5 flights/year from Boca Chica, so need to get to FL ASAP (maybe 3rd flight if first 2 are fairly successful?).  I think the ramp up is going to be fairly gradual, due to implementing lessons learned about launch support, mainly.
Or add a WR to the EIS when more flights are required. As has occurred multiple times at the other pads SpaceX operate.
The 5 launches a year 'limit' is no actual limit.

Offline ppb

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #49 on: 02/16/2023 10:49 pm »
Ugh, I can't believe you reference that guy.  Of all the very thin YouTuber space guys, he's one of the thinner ones.

Agree. I expressly said "His opinion". My post was more of a snarky remark, not meant to inform.
Too bad facial expressions can't be seen on posts. I was grinning ::)  because I thought his opinion was out there lol.
But most of all, he urges all of you.....
TA STAY ANGRY ABOUT SPACE!!!!

NASA's WB-57 reconnaissance aircraft's online schedule indicates it is on tap for the S24/B7 mission.  I love this platform's capabilities.   Should it (optimistically) be in Hawaii to cover the re-entry, or (pessimistically) be offshore from Boca Chica to be in position to cover ascent anomalies?   What's your call ... if you were SpaceX ... if you were NASA ... if you were you?

Online edzieba

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #51 on: 02/16/2023 11:28 pm »
NASA's WB-57 reconnaissance aircraft's online schedule indicates it is on tap for the S24/B7 mission.  I love this platform's capabilities.   Should it (optimistically) be in Hawaii to cover the re-entry, or (pessimistically) be offshore from Boca Chica to be in position to cover ascent anomalies?   What's your call ... if you were SpaceX ... if you were NASA ... if you were you?
Starship entry is intended to be over a very well instrumented test range (Pacific Missile Range Facility, Barking Sands) the mobile capabilities of the WB-57 are probably better suited to observing booster entry in the Gulf of Mexico.

In the update thread, the latest post mentions engine shields being removed, possibly for swapping out engines.

If that's the case, this would require another static fire with the new engines, right?
If it’s only a two or three, it may not be needed if they’ve already been acceptance fired in Texas.

For fun, 0.99 to the thirty-third power is 71.8 percent.  So say (hypothetically) each Raptor 2 has a .99 reliability for startup, the probability of at least one engine not successfully lighting up in a static fire (or launch) is still 28.3 percent.   

YES, by all means change out the two problem engines and just static fire the pair.  But I wouldn't continually repeat the 33-engine static fire until 100% successful.  The next time you fire/launch, you still have the 28.3 percent chance of one or more engines opting out. 

Only SpaceX has an informed estimate of Raptor 2 reliability ... yet if we reduce the hypothetical start reliability per engine to .98, then there's a 48.6% probability of not having all 33 engines starting up for liftoff.

Hence the very reason for the massive redundancy.

Yet take heart in that Booster 4, with only 29 Raptor 1s, was expected to send Ship 20 to orbit with just 410K-lbs of engine thrust each vs Booster 7's 33 Raptor 2s at 510K-lbs of thrust each (Wikipedia stats).  That's 11.9M-lbs of thrust (B4) verses 16.8M-lbs (B7).  Or put another way, Booster 7 could lose nine (9) Raptor 2s at liftoff and still have more thrust than Booster 4 would have had with all 29 of its Raptor 1s working.

Let's hopefully not delay the orbital launch attempt in the hunt for the perfect static fire.

Now if you want to do a full-33 engine attempt at liftoff thrust (Did Elon say 90 percent?) to see how the OLM holds up, well by all means

Offline matthewkantar

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #53 on: 02/17/2023 03:18 am »
If doable, I’d have the WB57 peep the stage separation. Get second stage ignition and maybe some booster maneuvering.

Offline Nevyn72

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #54 on: 02/17/2023 05:51 am »
If doable, I’d have the WB57 peep the stage separation. Get second stage ignition and maybe some booster maneuvering.

Does it have to be only one choice?
I thought there was more than one WB57 in NASA's fleet.

Offline Gonz58

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #55 on: 02/17/2023 10:57 am »
In the update thread, the latest post mentions engine shields being removed, possibly for swapping out engines.

If that's the case, this would require another static fire with the new engines, right?
If it’s only a two or three, it may not be needed if they’ve already been acceptance fired in Texas.

For fun, 0.99 to the thirty-third power is 71.8 percent.  So say (hypothetically) each Raptor 2 has a .99 reliability for startup, the probability of at least one engine not successfully lighting up in a static fire (or launch) is still 28.3 percent.   

YES, by all means change out the two problem engines and just static fire the pair.  But I wouldn't continually repeat the 33-engine static fire until 100% successful.  The next time you fire/launch, you still have the 28.3 percent chance of one or more engines opting out. 

Only SpaceX has an informed estimate of Raptor 2 reliability ... yet if we reduce the hypothetical start reliability per engine to .98, then there's a 48.6% probability of not having all 33 engines starting up for liftoff.

Hence the very reason for the massive redundancy.

Yet take heart in that Booster 4, with only 29 Raptor 1s, was expected to send Ship 20 to orbit with just 410K-lbs of engine thrust each vs Booster 7's 33 Raptor 2s at 510K-lbs of thrust each (Wikipedia stats).  That's 11.9M-lbs of thrust (B4) verses 16.8M-lbs (B7).  Or put another way, Booster 7 could lose nine (9) Raptor 2s at liftoff and still have more thrust than Booster 4 would have had with all 29 of its Raptor 1s working.

Let's hopefully not delay the orbital launch attempt in the hunt for the perfect static fire.

Now if you want to do a full-33 engine attempt at liftoff thrust (Did Elon say 90 percent?) to see how the OLM holds up, well by all means
I don't think I saw this hypothesis before. What if there was nothing wrong with the 2 raptors but instead something wrong with the OLM. If I understood correctly, the OLM provide spin-up gas for at least the 20 outer engines. Could it be possible that the OLM couldn't provide enough spin up gas to these 2 raptors because of some valve fault or not enough pressure ?
« Last Edit: 02/17/2023 10:58 am by Gonz58 »

Offline clongton

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #56 on: 02/17/2023 11:52 am »
If doable, I’d have the WB57 peep the stage separation. Get second stage ignition and maybe some booster maneuvering.

Does it have to be only one choice?
I thought there was more than one WB57 in NASA's fleet.

NASA has three (3) WB57s. They are based near JSC at Ellington Field.
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Offline Slothman

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #57 on: 02/17/2023 12:46 pm »
If doable, I’d have the WB57 peep the stage separation. Get second stage ignition and maybe some booster maneuvering.
I think all of those are doable by onboard cameras, no? Sure not in a 3rd person perspective, but current falcon onboards are pretty great already. Of course, if a stage fails, outside footage is very helpful, but probably not desired to be shown to the general audience.

I'm sure they'll have plenty of offboard (is that a term?) Surveillance going on, drones, telescopes, planes, maybe even satellites.that we'll never see (unless elon decides it's funny enough to share)
« Last Edit: 02/17/2023 12:57 pm by Slothman »

Online JayWee

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #58 on: 02/17/2023 01:14 pm »
If doable, I’d have the WB57 peep the stage separation. Get second stage ignition and maybe some booster maneuvering.
I think all of those are doable by onboard cameras, no? Sure not in a 3rd person perspective, but current falcon onboards are pretty great already. Of course, if a stage fails, outside footage is very helpful, but probably not desired to be shown to the general audience.

I'm sure they'll have plenty of offboard (is that a term?) Surveillance going on, drones, telescopes, planes, maybe even satellites.that we'll never see (unless elon decides it's funny enough to share)
On top of it - SH/SS should stage lower than F9 does. Easier to use telescope.

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Re: SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion
« Reply #59 on: 02/17/2023 02:56 pm »
   Should it (optimistically) be in Hawaii to cover the re-entry, or (pessimistically) be offshore from Boca Chica to be in position to cover ascent anomalies?   What's your call ... if you were SpaceX ... if you were NASA ... if you were you?
I would guess that the re-entry is observed.  See also here https://ntrs.nasa.gov/citations/20210020835
 In the appendix, the presentation slides have been converted into a PDF that can be read on a mobile phone.

Tags: Super-heavy 
 

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