Wiki Super Heavy/Starship - General Development Discussion

[scaesare]

Indeed impressive they are testing so soon after we saw the pieces being moved out.

So we were talking about potential water pressure levels earlier... I'm sure that was not a full pressure test. Interesting comment later in that Twitter thread:

The system appears to be in the process of being expanded and might eventually have double the amount of high pressure gas tanks feeding it.

 

[JB47394]

I'm sure that was not a full pressure test.

The extra tanks may also exist to provide a longer duration deluge.

 

[ecarfan]

New NSF video of the water deluge system test shows it from multiple camera angles. Interesting that the water jets seem much higher on one of the sides of the OLM closer to the tower. Also, water was released at several points close to the water tanks on the other side of the tower. I wonder why?

 

[mongo]

New NSF video of the water deluge system test shows it from multiple camera angles. Interesting that the water jets seem much higher on one of the sides of the OLM closer to the tower. Also, water was released at several points close to the water tanks on the other side of the tower. I wonder why?

There are two feeds to the plate, one splits to two manifolds the other feeds the third, so unbalance isn't surprising.

Blowoff/ vent down/ vacuum break valves on the top of the knees:

 

[scaesare]

Second shot with the dented up vertical tanks in the background lol..

Later angles from some distance away across the road and across the water channel are still surprisingly loud...

 

[ecarfan]

There are two feeds to the plate, one splits to two manifolds the other feeds the third, so unbalance isn't surprising.

Okay, thanks, that makes sense. I wonder if it was decided to channel more water to the side of the plate closest to the tower to provide it with additional protection? Looking at the video, that seems to be the case.

 

[JB47394]

Later angles from some distance away across the road and across the water channel are still surprisingly loud...

It's a noise cancellation system. When the booster fires its engines, the whole thing will be perfectly quiet because the water deluge system is just as loud, but precisely out of phase.

Yes, I'm joking.

 

[ecarfan]

NSF livestream right now showing B9 being moved to the launch area. S25 remains on its suborbital test stand, still needs a few tiles, the ones that came off during the static fire have not been replaced yet. Of course work remains ongoing around the OLM. One of the NSF hosts mentioned S26 is being scrapped.

 

[ecarfan]

B9 has been placed on the OLM! Will they do a static fire of just a few engines and use the deluge system at partial pressure? Many engines at full pressure? Eventually all engines at full pressure?

NSF livestream of the booster being placed on the OLM

 

[JB47394]

B9 has been placed on the OLM! Will they do a static fire of just a few engines and use the deluge system at partial pressure? Many engines at full pressure? Eventually all engines at full pressure?

NSF livestream of the booster being placed on the OLM

They'll walk into it, like they do all other testing. Spin prime testing, fire one engine - or a few engines - more engines, perhaps a short full engine test, then fire for the full duration that the booster will be thrusting against the plate (which is supposed to be much shorter than the first launch). I assume that all hot fires will use the deluge system.

They have an untested booster that needs to go through the normal test regimen, and they have a water deluge system for which they need to do integration testing. Perhaps more unit testing as well. They've also made repairs and changes to the launch mount itself, and those need to be tested.

The NSF guys commented that there's no hardware for hot firing on booster 9. If they intend to use that staging technique for the next test, then they've got a fair amount of work yet to do. I wonder if they plan on some kind of unit test of that. That is, static fire a Starship with the staging hardware from a booster under it. As far as I know, no existing test stand could handle that, and I doubt they'd do a static fire of the Starship on top of a gas pressurized booster. Perhaps they'll just leave it to the flight test and hope for the best. After all, they're not trying to save the booster from that flight.

Then there's the idea that SpaceX may junk booster 9 because it can't be built as a hot fire booster. Then we'd have to wait for booster 10 and its testing campaign.

It may well be a while. I've been guessing September, but they could run out a ways beyond that with all the changes they keep throwing into the mix. I wonder if SpaceX decided to switch to hot staging now (and possibly some other changes) because they had the time as a result of the launch mount repairs.

All that said, the booster going onto the launch mount last night was a pleasant surprise.

 

[ecarfan]

The NSF guys commented that there's no hardware for hot firing on booster 9. If they intend to use that staging technique for the next test, then they've got a fair amount of work yet to do.

I’m unclear on what you mean by “hot firing”. Do you mean “hot staging”?

If so, what you are saying is that B9 does not have the new additional top ring with vents that is needed for the hot staging technique, where the Starship sea level Raptors ignite just before stage sep and most of the booster Raptors shut down so that stage sep can occur.

Let me know if I’ve got that right. Thanks.

 

[mongo]

Prediction:
Static fire B9
*Swap engines that failed
Roll back to high bay
Fix issues from static fire and add hot staging ring
Roll back
*Swap engines if not done already
Static fire
Fix issues
Stack Starship
Fix clamp issues
Launch

Sea level testing of hot staging isn't practical. They could put a test ring/ done under the existing stand, but there's no way to simulate the separation and initial pressures are wrong (plus it's hard on the vacume engines).

 

[JB47394]

I’m unclear on what you mean by “hot firing”. Do you mean “hot staging”?

Yeah, sorry. I meant hot staging. Static firing. Hot staging.

If so, what you are saying is that B9 does not have the new additional top ring with vents that is needed for the hot staging technique, where the Starship sea level Raptors ignite just before stage sep and most of the booster Raptors shut down so that stage sep can occur.

That's what the NSF guys assert, and they're following all this much more closely than I am. SpaceX has mounted that ring with the ports onto a test article, but it doesn't look right as something that would work with hot staging.

Sea level testing of hot staging isn't practical. They could put a test ring/ done under the existing stand, but there's no way to simulate the separation and initial pressures are wrong (plus it's hard on the vacume engines).

Certainly separation testing is out of the question. You may be right that the initial pressures are so different that it wouldn't be a useful test. Simulations may suffice.

 

[Electroman]

then fire for the full duration that the booster will be thrusting against the plate (which is supposed to be much shorter than the first launch)

How so? Why would the duration be much shorter? Shouldn’t the booster take the same duration and thrust against the launch plate as last time?

 

[arnolddeleon]

How so? Why would the duration be much shorter? Shouldn’t the booster take the same duration and thrust against the launch plate as last time?

With static fire the booster doesn't leave stand (that's the plan anyway). With an actual launch the booster leaves so the impact on the stand is likely less.

 

[ICUDoc]

that's the plan anyway

 

[JB47394]

How so? Why would the duration be much shorter? Shouldn’t the booster take the same duration and thrust against the launch plate as last time?

The first launch used an ignition sequence that took a long time to come up to power and they're changing something about the firing sequence, or the throttle schedule, whatever. Then there's the hope that they won't lose any engines during startup, which also slows the liftoff. Changes like this shouldn't come as too much of a surprise given the many things they must have learned from the first launch.

 

[JB47394]

SpaceX has mounted that ring with the ports onto a test article, but it doesn't look right as something that would work with hot staging.

Here's a video from Marcus House's channel that shows test article 24.2 with the odd ring (video link is timestamped). The number says that it's a Starship test article, and this structure also has a payload door on it. I have no idea what the ports are for, and Marcus didn't speculate.

Edit: Later in the same video, Marcus talks about a ring section that was spotted and is thought to be a proper vented design.

 

[mongo]

Here's a video from Marcus House's channel that shows test article 24.2 with the odd ring (video link is timestamped). The number says that it's a Starship test article, and this structure also has a payload door on it. I have no idea what the ports are for, and Marcus didn't speculate.

The port are theoretically for the test rams to go through to push/ pull the test articles.

 

[JB47394]

The port are theoretically for the test rams to go through to push/ pull the test articles.

What sort of test would need rams to pass through to the interior of a Starship?

Looking at it again, my guess is that this is for booster connection points for the outer ring of engines. I think the number of ports matches. Obviously, this ring being mounted on a Starship test article doesn't jibe with that theory at all.