SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion

[russianhalo117]

Anyone know why they didn't use the water deluge?  At least I didn't see evidence of it.

What they call water deluge is more consistent when compared with other domestic and international launch complexes with launch abort and pad fire suppression system given nozzles have horizontal and diagonally upwards facing high pressure nozzles. Water deluge and sound suppression systems generally use a different design using high flow rate rainbird nozzles (similar concept used in organ pipe slit design) in addition to a high concentration ratio of nozzles. The latter two systems do kot physically appear to be present whereas the fire suppression system seems to have a reasonable number of nozzles present.

Agree.  And I went back and watched the video, and they used their suppression system on S24, not B7's SF.  Although I still don't know why they either don't have or haven't used anything under the OLM.

Only the suborbital pads have a ground mounted deluge system. OLM doesn't have any of that visually so far. There is only the mounts fire suppression system.

[CorvusCorax]

Only the suborbital pads have a ground mounted deluge system. OLM doesn't have any of that visually so far. There is only the mounts fire suppression system.

If I remember right from various discussions in various threads here, the issue was the amount of water needed for a 33 engine booster sound suppression system by water deluge was so large, SpaceX would have needed to build this (once planned) sea water desalination plant at the launch site, which was problematic in respect to power usage, environmental assessment, etc...

So in good old Elon fashion, SpaceX decided "best part is no part" and went for "no water deluge is the best water deluge" -- a decision that if I remember right was commented on by Musk on Twitter too along the lines of "might have been a mistake, we shall see.."

either way, right now the orbital launch mount doesn't have water deluge because there's a lack of large enough water towers (*sic*) at Boca Chica (or rather no means to fill them), and as such not enough water to support it.

[rsdavis9]

I could have sworn that I saw a test of the OLM water suppression. I don't have the time to filter through all the images.

[edzieba]

On booster frost lines: The booster has a large 'sump' tank that act as the methane distribution manifold ('Methdusa', a'la 'Loxtopus' on F9). In order for any engine to fire on the booster, this sump tank needs to fill before you can even start filling the main Methane tank. There will be no frost line visible if only the sump tank is filled, as it does not contact the outer surface. Once the Methane tank starts to fill, it would need to fill above the top of the common dome before frost would start forming on the tank skin.
There does not appear to be a dedicated LOX sump or manifold for he outer engines (there may be one for the centre engines) so feeding propellants for them only requires a sufficient fill above the portion of the aft dome where the outlets are located. If the fill line is below the point where the aft dome is joined to the tank wall, then there will also not be a frost line.

An exception is that if a propellant tank is left partially filled for enough time for the vapour in the tank to cool the tank walls below 0°C. This would require the propellant to be left to boil for a protracted period, and with sub-chilled propellants it is likely SpaceX would perform a re-cycle (drain prop back to tank farm, then re-load via sub-chiller) before that could happen.

tl;dr low propellant loads will not result in a frost line visible on the outside of the booster.

[TergenFlerg]

"So in good old Elon fashion, SpaceX decided "best part is no part" and went for "no water deluge is the best water deluge" -- a decision that if I remember right was commented on by Musk on Twitter too along the lines of "might have been a mistake, we shall see.."

I think that comment was regarding a flame diversion trench.

[lykos]

I think there is a big confusion here.
- the comment was for flame diverter for sure
- there is a big water tank and pipes going to OLM. Is it empty or only for fire surpressing system?
- Starship-start without water would be a very big mass !

[edzieba]

Booster 7 is leaving the pad. It would be reasonable to conclude either the pad (e.g. adding igniters and/or other fire suppression systems, or needing space to work on the damaged chopstick arm actuator), or booster, (e.g. if only a handful of engines were fully plumbed in before the initial "do it now!" rollout) require work before they can proceed to multiple engine firings. If no work was required, moving the booster back to the build site and mounting additional engines first does not speed up testing and risks more engines vs. scaling up to an eventual 20-engine firing before rolling back for centre engine install.

[SeaRaven]

Only the suborbital pads have a ground mounted deluge system. OLM doesn't have any of that visually so far. There is only the mounts fire suppression system.

If I remember right from various discussions in various threads here, the issue was the amount of water needed for a 33 engine booster sound suppression system by water deluge was so large, SpaceX would have needed to build this (once planned) sea water desalination plant at the launch site, which was problematic in respect to power usage, environmental assessment, etc...

So in good old Elon fashion, SpaceX decided "best part is no part" and went for "no water deluge is the best water deluge" -- a decision that if I remember right was commented on by Musk on Twitter too along the lines of "might have been a mistake, we shall see.."

either way, right now the orbital launch mount doesn't have water deluge because there's a lack of large enough water towers (*sic*) at Boca Chica (or rather no means to fill them), and as such not enough water to support it.

There is a water deluge system of sorts if you look closely.  I suppose the radial nozzles is the FSS you are referring to. The  dark gray circular dodecagon pipe must serve some purpose, and I can only think of water.  The outer engine spinup supply is higher up.

[Jim]

There is a water deluge system of sorts if you look closely.  I suppose the radial nozzles is the FSS you are referring to. The  dark gray circular dodecagon pipe must serve some purpose, and I can only think of water.  The outer engine spinup supply is higher up.

What FSS?   That is a shuttle specific term.

[Herb Schaltegger]

There is a water deluge system of sorts if you look closely.  I suppose the radial nozzles is the FSS you are referring to. The  dark gray circular dodecagon pipe must serve some purpose, and I can only think of water.  The outer engine spinup supply is higher up.

What FSS?   That is a shuttle specific term.

I think in this context, “FSS” is supposed to denote “Fire Suppression System.”

[baking]

There is a water deluge system of sorts if you look closely.  I suppose the radial nozzles is the FSS you are referring to. The  dark gray circular dodecagon pipe must serve some purpose, and I can only think of water.  The outer engine spinup supply is higher up.

What FSS?   That is a shuttle specific term.

I think in this context, “FSS” is supposed to denote “Fire Suppression System.”

It wouldn't be a NSF post without an acronym, FFS.

[Tangilinear Interjar]

Only the suborbital pads have a ground mounted deluge system. OLM doesn't have any of that visually so far. There is only the mounts fire suppression system.

If I remember right from various discussions in various threads here, the issue was the amount of water needed for a 33 engine booster sound suppression system by water deluge was so large, SpaceX would have needed to build this (once planned) sea water desalination plant at the launch site, which was problematic in respect to power usage, environmental assessment, etc...

So in good old Elon fashion, SpaceX decided "best part is no part" and went for "no water deluge is the best water deluge" -- a decision that if I remember right was commented on by Musk on Twitter too along the lines of "might have been a mistake, we shall see.."

either way, right now the orbital launch mount doesn't have water deluge because there's a lack of large enough water towers (*sic*) at Boca Chica (or rather no means to fill them), and as such not enough water to support it.

There is a water deluge system of sorts if you look closely.  I suppose the radial nozzles is the FSS you are referring to. The  dark gray circular dodecagon pipe must serve some purpose, and I can only think of water.  The outer engine spinup supply is higher up.

I'm pretty sure that the hex'ish pipe is a nitrogen purge/fire suppression system. If you follow the connections it goes back to some insulated pipes.

The water system is fed through the radial oriented pipes with nozzles that are just below the nitrogen pipe.

[alugobi]

Is it really necessary or efficient to have to take the booster back in order to install additional engines?  Update thread comments says additional engines is the reason.  I'm skeptical.  They have a working platform now that should be quite adequate for that purpose.

[dabomb6608]

Is it really necessary or efficient to have to take the booster back in order to install additional engines?  Update thread comments says additional engines is the reason.  I'm skeptical.  They have a working platform now that should be quite adequate for that purpose.

For installation of 13 raptors it is likely more efficient to do so in a dedicated bay than it is while mounted to OLM. If it was only a couple raptors it might be a different story.

[CorvusCorax]

"So in good old Elon fashion, SpaceX decided "best part is no part" and went for "no water deluge is the best water deluge" -- a decision that if I remember right was commented on by Musk on Twitter too along the lines of "might have been a mistake, we shall see.."

I think that comment was regarding a flame diversion trench.

You are right, I misremembered.

That being said, I can't remember seeing any water deluge being used on the OLM ever. Only on pad A and B. The former landing pad had one of these remote controlled fire suppression cannons.

Also for real water deluge you'd need a tall tower for some head pressure and volume. I don't see any such infrastructure anywhere near the Orbital pad.. Compare with the thickness of water pipes on Pad 39A or in Vandenberg SFB.

[edzieba]

A deluge system for the OLP is installed and was tested, but it produced more of a light mist:

[alugobi]

Is it really necessary or efficient to have to take the booster back in order to install additional engines?  Update thread comments says additional engines is the reason.  I'm skeptical.  They have a working platform now that should be quite adequate for that purpose.

For installation of 13 raptors it is likely more efficient to do so in a dedicated bay than it is while mounted to OLM. If it was only a couple raptors it might be a different story.

Why?

[StevenOBrien]

Is it really necessary or efficient to have to take the booster back in order to install additional engines?  Update thread comments says additional engines is the reason.  I'm skeptical.  They have a working platform now that should be quite adequate for that purpose.

For installation of 13 raptors it is likely more efficient to do so in a dedicated bay than it is while mounted to OLM. If it was only a couple raptors it might be a different story.

Why?

The OLM platform is several stories off the ground. I'm sure it's much easier to work with engines from ground level in the highbay, especially when 13 need to be installed at once.

Also, it's a choice between transporting 13 raptors to the launch site or transporting one B7 back to the build site.

Even if it was possible to install 13 on the OLM, other reasons I can think of are:

- They want to test the chopsticks after the hydraulic failure, and B7 interferes with that
- There are still repairs to be done on the OLM that B7 would interfere with
- They want to cryoproof B8 while B7 is getting raptors installed

[peregrine30]

Is it really necessary or efficient to have to take the booster back in order to install additional engines?  Update thread comments says additional engines is the reason.  I'm skeptical.  They have a working platform now that should be quite adequate for that purpose.

For installation of 13 raptors it is likely more efficient to do so in a dedicated bay than it is while mounted to OLM. If it was only a couple raptors it might be a different story.

Why?

The OLM platform is several stories off the ground. I'm sure it's much easier to work with engines from ground level in the highbay, especially when 13 need to be installed at once.

Also, it's a choice between transporting 13 raptors to the launch site or transporting one B7 back to the build site.

Even if it was possible to install 13 on the OLM, other reasons I can think of are:

- They want to test the chopsticks after the hydraulic failure, and B7 interferes with that
- There are still repairs to be done on the OLM that B7 would interfere with
- They want to cryoproof B8 while B7 is getting raptors installed

or they feel some tweaks/enhancements need to be done after looking at the long SF data...

[alugobi]

The new platform effectively makes it ground level when it's raised.  The various camera views show dudes walking around in that space as though they were on the floor.  The raptors are easily trucked; doesn't require the big mover. 

Your additional reasons are more compelling.  Working on the engines is much less so now, with that new raiseable floor.

Edit:  I wish Musk would say something about this, to give us a better idea of the status of B7.