Author Topic: SpaceX Texas launch site Discussion and Updates - Thread 12  (Read 1292912 times)

Offline InterestedEngineer

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1380 on: 11/16/2022 06:47 pm »


By some simple math, the recent Booster static fire of 14 engines retired a good chunk of risk on the hold downs and the OLM structure.

14 * 250t thrust = 3,500t of thrust.   The booster probably ended up with 3,200t of net upward force on the hold downs by the end of the static fire.

This is more than the 2,500t needed for an orbital flight, by at least 20% margin.

Congrats SpaceX on not 'launching' the booster!

Are we sure the engines were throttled to 100%?

Cheers, Martin

Min throttle is 40%. I'm not sure they can start engines at min throttle, does anyone know?

Assuming since the start is sequential and they can throttle down relatively quickly so they can maintain at least 50% average throttle, then 50% of 3,500t is 1,750t.

I'm not sure why they would min-throttle and not actually test the hold downs  to full strength though, so barring other evidence I would assume they would not min-throttle.

If they haven't tested the hold-downs to full strength, then they are delaying that risk-reduction to a fully stacked system test fire, which risks a lot more hard to replace OLM infrastructure because more fuel is present for a ooopsie.   

The 14 engine booster-only test with minimum fuel (per the frost lines) is the minimum-consequence test i can think of to test all those risk items I noted.

Online FutureSpaceTourist

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1381 on: 11/16/2022 08:56 pm »

Offline InterestedEngineer

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1382 on: 11/16/2022 10:40 pm »
Is there any evidence of a helium supply (tanks, lines) for the OLM?

Offline InterestedEngineer

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1383 on: 11/16/2022 10:50 pm »


I don't see any major damage.  Some peeled paint on pipes that are about to be covered anyways.

Quite impressive, better than I thought it'd be with 650*14 = 9.1t / sec of exhaust at 3.21km/sec, kinetic energy rate of 47GW and thermal energy rate of 35GW.

I don't think the takeoff rates of 2.4x the above energy numbers are going to be a problem for the base of OLM.

Offline alugobi

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1384 on: 11/16/2022 11:10 pm »
We can't see the surface below.  I still don't think that that was ice raining down post-fire.

Offline InterestedEngineer

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1385 on: 11/17/2022 12:00 am »
We can't see the surface below.  I still don't think that that was ice raining down post-fire.

The winds 50 meters from the pad will exceed Mach 1, so the debris may be from within 50-200 meters of the OLM and not the OLM itself.

A virtual cone forms at the base of the OLM so I doubt the bottom is damaged (look up the college junior physics problem "flow perpendicular to surface".  Also, they just parked the OLM lift under the pad, so if there's damage it can't be very much.

Offline InterestedEngineer

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1386 on: 11/17/2022 12:07 am »


I don't see any major damage.  Some peeled paint on pipes that are about to be covered anyways.

Quite impressive, better than I thought it'd be with 650*14 = 9.1t / sec of exhaust at 3.21km/sec, kinetic energy rate of 47GW and thermal energy rate of 35GW.

I don't think the takeoff rates of 2.4x the above energy numbers are going to be a problem for the base of OLM.

Note lack of damage higher up indicating almost no rebound (red oval highlighted)

The clouds that exited from the OLM base also indicating the flow taking a nice 90 degree turn.

 The shape of the discoloration and the 90 degree turn makes it look like a virtual "boundary layer" cone was formed that turns the flow.

https://www.researchgate.net/figure/Schematic-diagram-of-flow-physics-of-impinging-jet_fig1_233731586

Offline CorvusCorax

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1387 on: 11/17/2022 06:45 pm »
Is the amount of wear on the launchmount, inc. leg paint and/or metal a concern to SpaceX? Or does it look much worse than it is?

Offline RamsesBic

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1388 on: 11/17/2022 09:25 pm »
Is the amount of wear on the launchmount, inc. leg paint and/or metal a concern to SpaceX? Or does it look much worse than it is?

I don't know, but I am keeping an eye on the work being done to it. I expect new concrete at some point, but if we also see new steel being added to the inner surfaces of the legs then that would clearly indicate that the damage was more than expected. If we don't, then it just is paint and maybe some minor pitting.

One thing they have not had time to add yet are the covers that would seal in the piping on the legs from most of the hot gases. Such covers have been spotted. They have hinges and bolts (to give them access).

Offline Alvian@IDN

Noted for flame trench AND proper water deluge concerner, spoiler: it wouldn't necessarily save the facilities
https://twitter.com/DutchSatellites/status/1593520419872641024?t=DThCON3HLtbMfLUiyT0Icg&s=19

Unlike SLS ofc, SpaceX is most likely planning to conduct 33 engine static fire(s) before launch, meaning they will get most of the real-world data on how the launch site will be performing. And with higher cadence, they're needing it sooner rather than later
« Last Edit: 11/18/2022 10:53 am by Alvian@IDN »
My parents was just being born when the Apollo program is over. Why we are still stuck in this stagnation, let's go forward again

Offline kevinof

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1390 on: 11/18/2022 09:23 am »
Well NASA and the SLS team have a couple of years to fix it.  :)

Just shows you the power of these heavy boosters - Even with all the planning you can still get it wrong. As you say at least SpaceX is seeing the damge as they go, learning, fixing and going again.

Noted for flame trench-concerner, spoiler: it wouldn't necessarily save the facilities
https://twitter.com/DutchSatellites/status/1593520419872641024?t=DThCON3HLtbMfLUiyT0Icg&s=19

Unlike SLS ofc, SpaceX is most likely planning to conduct 33 engine static fire(s) before launch, meaning they will get most of the real-world data on how the launch site will be performing. And with higher cadence, they're needing it sooner rather than later
« Last Edit: 11/18/2022 09:24 am by kevinof »

Online DanClemmensen

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1391 on: 11/18/2022 02:58 pm »
Well NASA and the SLS team have a couple of years to fix it.  :)

Just shows you the power of these heavy boosters - Even with all the planning you can still get it wrong. As you say at least SpaceX is seeing the damge as they go, learning, fixing and going again.
It's a bit difficult(!) to test SRBs incrementally on the launch pad. The SRBs provide about 75% of the liftoff thrust for SLS. We are seeing a secondary benefit of the decision to build a fully-reusable system.

Offline kevinof

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1392 on: 11/18/2022 03:01 pm »
Well NASA and the SLS team have a couple of years to fix it.  :)

Just shows you the power of these heavy boosters - Even with all the planning you can still get it wrong. As you say at least SpaceX is seeing the damge as they go, learning, fixing and going again.
It's a bit difficult(!) to test SRBs incrementally on the launch pad. The SRBs provide about 75% of the liftoff thrust for SLS. We are seeing a secondary benefit of the decision to build a fully-reusable system.
Yes good point on the SRBs. SpaceX should be able to take steps (as they are with the blast panels) to reduce the damage but it will be interesting to see how it fares once the booster lifts off and the blast hits the top of the launch mount.

Online FutureSpaceTourist

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1393 on: 11/18/2022 04:55 pm »
https://twitter.com/chrisk_91/status/1593664051992731657

Quote
SpaceX has added additional cladding to the Orbital Launch Tower.

@NASASpaceflight

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1394 on: 11/18/2022 05:08 pm »
I had a feeling we'd be seeing a lot more cladding to protect the OLM legs, at the minimum.
Aviation/space enthusiast, retired control system SW engineer, doesn't know anything!

Offline EL_DIABLO

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1395 on: 11/18/2022 05:27 pm »
What's up with the gaps?

Offline InterestedEngineer

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1396 on: 11/18/2022 06:17 pm »
Well NASA and the SLS team have a couple of years to fix it.  :)

Just shows you the power of these heavy boosters - Even with all the planning you can still get it wrong. As you say at least SpaceX is seeing the damge as they go, learning, fixing and going again.
It's a bit difficult(!) to test SRBs incrementally on the launch pad. The SRBs provide about 75% of the liftoff thrust for SLS. We are seeing a secondary benefit of the decision to build a fully-reusable system.

Iteration is so valuable that it should preclude non-reusable or hard to replicate expensive components from a design, such as SRBs.

Which is a main concern about the tower/OLM.   It's the one place in Starship development that violates this rule.

Hopefully small iterations are enough to cover this.

Offline Robotbeat

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1397 on: 11/18/2022 06:19 pm »
Well NASA and the SLS team have a couple of years to fix it.  :)

Just shows you the power of these heavy boosters - Even with all the planning you can still get it wrong. As you say at least SpaceX is seeing the damge as they go, learning, fixing and going again.
It's a bit difficult(!) to test SRBs incrementally on the launch pad. The SRBs provide about 75% of the liftoff thrust for SLS. We are seeing a secondary benefit of the decision to build a fully-reusable system.

Iteration is so valuable that it should preclude non-reusable or hard to replicate expensive components from a design, such as SRBs.

Which is a main concern about the tower/OLM.   It's the one place in Starship development that violates this rule.

Hopefully small iterations are enough to cover this.
The tower isn’t that expensive, tho. Cheap enough they’re basically building a spare as far as we can tell. Probably costs less than a complete Starship/SuperHeavy stack.
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Offline alugobi

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1398 on: 11/18/2022 07:01 pm »
The time to remove and replace a too-damaged tower would be a hefty expense.

Offline russianhalo117

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Re: SpaceX Texas launch site Discussion and Updates - Thread 12
« Reply #1399 on: 11/18/2022 07:26 pm »
What's up with the gaps?
Mechzilla carriage clearance henceangle metal. metal.

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