Author Topic: OLM height and width  (Read 5139 times)

Offline weileyc

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OLM height and width
« on: 01/17/2023 12:45 am »
With every test of booster, we see that the pad under the OLM gets destroyed.  Water deluge would help, but I wonder if it would be better to increase height and width of the OLM to give the exhaust more room to expand and dissipate energy.

SpaceX has already proven that it can lift using the chopsticks.  Increasing OLM height would require the tower to also increase in height.

Attached is bad paint diagram showing two towers (two chopsticks allow for simultaneous lifting of booster and ship.  Also doubles possible catch area.  Both could also provide stability before launch).  It also shows two possible test stand locations that would allow for lift using chopsticks.

Increased height may require second set of pumps to supply the vehicles.

Please forgive my bad paint and perspective.

Thoughts?
« Last Edit: 01/17/2023 12:47 am by weileyc »

Offline Bob Niland

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Re: OLM height and width
« Reply #1 on: 01/17/2023 01:01 am »
My impression is that the original Texas OLM has already had its design height raised once, via those vertical sections above the knee bends.
It makes me wonder if the Florida OLMs are the same or a different height. They omit the knees.
Chances are this has already been explored here and escaped my notice.
But because people are doing various sims on all this, I suspect that pretty close to accurate numbers are available.
Working for SX could be exhilarating, as long as the job description doesn't include Master PERT Chart.

Offline edzieba

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Re: OLM height and width
« Reply #2 on: 01/17/2023 10:57 am »
Increasing vehicle height above ground also increases required pump power to move propellants into the vehicle, and pressures in the plumbing carrying those fluids. You might also start to encounter weird issues with long vertical plumbing runs, like opening or closing valves in partially full pipes resulting in spontaneous boiling from the pressure drop between the top and bottom of the run, or vacuum induced collapse. Certainly seems like more headache to add extra cryogen handling systems than to add a water handling system for deluge if needed.

Offline alugobi

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Re: OLM height and width
« Reply #3 on: 01/17/2023 04:07 pm »
Concrete is inexpensive, easy to hammer out and replace.

Offline weileyc

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Re: OLM height and width
« Reply #4 on: 01/17/2023 04:31 pm »
Concrete is inexpensive, but takes time to cure.  If rapid reuse is to be achieved, the concrete needs to survive.

Offline edzieba

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Re: OLM height and width
« Reply #5 on: 01/17/2023 04:44 pm »
Concrete is inexpensive, but takes time to cure.  If rapid reuse is to be achieved, the concrete needs to survive.
Concrete can also be pre-cast into blocks offsite and lifted into place, in the event launch mount recycle time needs to be faster than the few hours/days for pouring and curing.

Online eriblo

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Re: OLM height and width
« Reply #6 on: 01/17/2023 05:42 pm »
There is likely little need to make the OLM taller to increase area for the plume to exit in as it does not even fill the current openings.

Problems with the pad surface being damaged are probably easier dealt with by improving the surface itself. Remember that SpaceX has 10s of thousands of seconds of firing Raptors into flame diverters at McGregor. They have a better idea than anyone what happens to the structures involved...

With the Fondag pads the damage appears to be a few cm of melted/ablated material directly underneath each engine. If there is no large debris this might be fine for now.

Offline alugobi

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Re: OLM height and width
« Reply #7 on: 01/17/2023 07:42 pm »
Concrete is inexpensive, but takes time to cure.  If rapid reuse is to be achieved, the concrete needs to survive.
At BC at least, they aren't approved for the kind of launch cadence that would be considered rapid.  Maybe in future, but not now, and perhaps even foreseeable. 

Online DanClemmensen

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Re: OLM height and width
« Reply #8 on: 01/17/2023 07:51 pm »
Concrete is inexpensive, but takes time to cure.  If rapid reuse is to be achieved, the concrete needs to survive.
At BC at least, they aren't approved for the kind of launch cadence that would be considered rapid.  Maybe in future, but not now, and perhaps even foreseeable.
They intend to launch five times in 2023 with the first launch NET late February, so a rate of once every two months, probably with a new booster each time. but a new booster traditionally requires a 33-engine static fire test in addition to the launch, so that's ten damage events, which is an average of once a month. That's a lot of concrete and not much time to cure it.

BC is supposed to be the prototyping site for the OLM, not just the Starship. They will try to build something that can be replicated at KSC and later at other sites. Those sites are supposed to support rapid reuse.


Offline alugobi

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Re: OLM height and width
« Reply #9 on: 01/17/2023 08:02 pm »
The new concrete type they're using has a cure time measured in days, I believe. 

Anyway, the OP proposes a radical hardware design change that just doesn't seem practical, for reasons of piping, pumping, and service, as mentioned, and is a lot of overkill to spare some concrete.

Online DanClemmensen

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Re: OLM height and width
« Reply #10 on: 01/17/2023 08:47 pm »
The new concrete type they're using has a cure time measured in days, I believe. 

Anyway, the OP proposes a radical hardware design change that just doesn't seem practical, for reasons of piping, pumping, and service, as mentioned, and is a lot of overkill to spare some concrete.
I doubt that any radical redesign is needed. However, I also doubt that the operational design will require replacing the concrete after each use.

Offline alugobi

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Re: OLM height and width
« Reply #11 on: 01/17/2023 09:01 pm »
Did you see the comparative sizes of the two launch mounts in the OP? I'd call that a radical redesign. You could see the proposed setup from over the horizon.

Offline weileyc

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Re: OLM height and width
« Reply #12 on: 01/17/2023 09:19 pm »
Did you see the comparative sizes of the two launch mounts in the OP? I'd call that a radical redesign. You could see the proposed setup from over the horizon.

I did say that my perspective was off.  I also haven't done any calculations on what height and width would be needed.  The drawing was only to scale in relation between tower and olm.

Of course any change would have to pass cost benefit analysis.

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