totm nov 2023 SpaceX Discussion Thread

[RCgothic]

19 hours ago, caecilliusinhorto said:

I thought the reason they made the launch mount so high was so that they wouldn't have to use water deluge systems?

Another reason is a high water table isn't conducive to flame trenches.

I believe they're also trying to get by without a blast deflector, although not sure why given it's a relatively cheap and easy addition.

Edited December 31, 2021 by RCgothic

[magnemoe]

1 hour ago, RCgothic said:

Another reason is a low water table isn't conducive to flame trenches.

I believe they're also trying to get by without a blast deflector, although not sure why given it's a relatively cheap and easy addition.

Think you meant high water table, KSC has the same issue and they solved it by making the launch pad on artificial hills because the needed to access the pad with crawlers. 
Since starship and booster is lifted onto the pad they simply raised it. 
And yes an simple blast deflector is cheap and easy to make, its not that they are low on scrap metal after all  
 

[tater]

 

 

[tater]

 

 

[Beccab]

Either there's a lift soon or they will be replaced
Edit: worth watching this

 

Edited January 3, 2022 by Beccab

[CatastrophicFailure]

 

 

[cubinator]

And here I am fretting over 300 psi...

[Beccab]

 

[JoeSchmuckatelli]

8 hours ago, Beccab said:

 

How does moving a tank into the nose cone help develop a ship that can carry payloads or people? 

[Beccab]

9 minutes ago, JoeSchmuckatelli said:

How does moving a tank into the nose cone help develop a ship that can carry payloads or people? 

...there's already a tank in the nose, the lox header tank. You may be overestimating how big these are:

There's nothing preventing moving them back down the ship ITS style (see below), but currently they give a better center of mass on the way down

Edited January 4, 2022 by Beccab

[JoeSchmuckatelli]

5 minutes ago, Beccab said:

give a better center of mass on the way down

That makes sense for testing / learning to fly standpoint.  However - at some point I expect SS to carry payloads, and the craft is expected to deliver the payloads to space and land without, correct? 

[Beccab]

6 minutes ago, JoeSchmuckatelli said:

That makes sense for testing / learning to fly standpoint.  However - at some point I expect SS to carry payloads, and the craft is expected to deliver the payloads to space and land without, correct? 

We ultimately don't know what they will end up doing, but keeping it is the currenty plan. See, for example:

Again, plans change fast with especially with tanks (they switched the LOX and LCH4 tanks on Superheavy two times already between prototypes and moved the header tank twice I believe), but I don't see the header tank in the nose as a problem. One of the plans for it is to keep it insulated for Martian landing for example, not sure if that would be easier or harder inside the empty LOX tank

[Beccab]

The berms at the original Superheavy landing pads are being removed as the suborbital tank farm is being reconfigured to provide additional LCH4 to the orbital launch tower - the second and likely last consequence of the methane tanks installation issue that prevents them from being used that the twitter thread talked about last week. The suborbital pad and the horizontal tanks will provide enough LCH4 for the orbital flight (as well as a few recycles likely) in the near future until a permanent replacement is in place

[magnemoe]

58 minutes ago, JoeSchmuckatelli said:

That makes sense for testing / learning to fly standpoint.  However - at some point I expect SS to carry payloads, and the craft is expected to deliver the payloads to space and land without, correct? 

I say the nose is of little use for cargo anyway as its narrowing. Assuming the do common bulkhead this will be an larger sphere wrapping around the LOX tank. Not that much larger because of the cube law. Now it might be an problem with the forward RCS but I kind of suspect they need to insulate the header tanks for long missions in any case. 
One benefit of this is that the methane header tank is a bit stupid, it need to have valves at the bottom of main tank to fuel full trust burns but it will leave fuel in the main tank unless you also burn half the fuel in the header tank. You will then have to pump it into the header tank. Yes I'm sure its pumps to top off the header tanks in orbit anyway.

For manned flights well you have lots of fuel for an abort system . 

[JoeSchmuckatelli]

The graphic Beccab showed is interesting.  I guess I always expected some variation on what Neutron is doing, given that the payload could just slide straight forward.  With that illustration, deployment is going to be slightly more complicated - but I can't see any reason why it should not work.

Also - every graphic I've seen of a manned lander shows no nose deployment stuff - just side doors and elevators.  I guess I kind of expected a good 1/3 to 1/2 of the structure to be where the command crew sat (and yes, I know everything is automated so it does not matter where they sit... but traditions, you know).

[Rakaydos]

2 minutes ago, JoeSchmuckatelli said:

The graphic Beccab showed is interesting.  I guess I always expected some variation on what Neutron is doing, given that the payload could just slide straight forward.  With that illustration, deployment is going to be slightly more complicated - but I can't see any reason why it should not work.

Also - every graphic I've seen of a manned lander shows no nose deployment stuff - just side doors and elevators.  I guess I kind of expected a good 1/3 to 1/2 of the structure to be where the command crew sat (and yes, I know everything is automated so it does not matter where they sit... but traditions, you know).

The short explanation is that heat shields dont fold well, without a lot of difficult and expansive (and heavy) extra engineering. It's easier to have a 1-sided door open 90 degrees, set decoupler strength to 0 and rotate out of the way.

[Beccab]

11 minutes ago, JoeSchmuckatelli said:

The graphic Beccab showed is interesting.  I guess I always expected some variation on what Neutron is doing, given that the payload could just slide straight forward.  With that illustration, deployment is going to be slightly more complicated - but I can't see any reason why it should not work.

Yup, the chomper bay is part the official Starship cargo currently. From the Spacex website:

Almost certainly it won't be as large as in the graphics due to heat shielding requirements, but it's definitely going to be a considerable portion of the Starship nosecone. However, if there's a way to split partially the heat shield ala Shuttle landing gear then the problem is solved, which could happen given that it would only become relevant after the payload is deployed and the empty Starship is reentering (and thus fits in the general Starship testing regime)
Worth mentioning that the deployment for large satellites could be similar to what the Shuttle did for the IUS, angling the payload out of the cargo bay and then deploying it

Edited January 4, 2022 by Beccab

[JoeSchmuckatelli]

10 minutes ago, Beccab said:

the deployment for large satellites

...and telescopes larger than Webb is part of the reason I'm so excited about the potential of SX and SS.

Hoping '22 is a year filled with success for those folks.  So much to look forward to!

[CatastrophicFailure]

Didn’t Elon say recently they were going to stretch Starship, possibly starting with 24?  That could be the tank issue right there, no cargo space really lost (actually gained) if they put another tank in the nose and add another barrel section, too. 

[Beccab]

4 minutes ago, CatastrophicFailure said:

Didn’t Elon say recently they were going to stretch Starship, possibly starting with 24?  That could be the tank issue right there, no cargo space really lost (actually gained) if they put another tank in the nose and add another barrel section, too. 

Not 24, but yes it's going to be stretched - 8 meters is the maximum possible structurally may that be fuel or payload (probably less initially)

[kerbiloid]

41 minutes ago, Beccab said:

Works against the space pests either.

Spoiler

 

[Beccab]

1 hour ago, Beccab said:

The berms at the original Superheavy landing pads are being removed as the suborbital tank farm is being reconfigured to provide additional LCH4 to the orbital launch tower - the second and likely last consequence of the methane tanks installation issue that prevents them from being used that the twitter thread talked about last week. The suborbital pad and the horizontal tanks will provide enough LCH4 for the orbital flight (as well as a few recycles likely) in the near future until a permanent replacement is in place

Was going to add it as an edit but since it's relatively important:

Methane deliveries to the suborbital tank farm have begun, meaning something is going to do a static fire or WDR soon enough. Wether that is S20 or B4 isn't yet clear since both completed at least ambient testing (and B4 is hooked again to its crane, perhaps going back to the OLM once the work on the booster quick disconnect is complete). A lot of LOX has also been delivered to both the suborbital and orbital tank farms

Edited January 4, 2022 by Beccab

[magnemoe]

3 hours ago, JoeSchmuckatelli said:

The graphic Beccab showed is interesting.  I guess I always expected some variation on what Neutron is doing, given that the payload could just slide straight forward.  With that illustration, deployment is going to be slightly more complicated - but I can't see any reason why it should not work.

Also - every graphic I've seen of a manned lander shows no nose deployment stuff - just side doors and elevators.  I guess I kind of expected a good 1/3 to 1/2 of the structure to be where the command crew sat (and yes, I know everything is automated so it does not matter where they sit... but traditions, you know).

Neutron split the nose, Starship has an large door open up like an mouth. not an huge fan of this design, yes it might be the most lightweight but it makes deployment of groups of satellites hard as you can only deploy forward and integration of new payloads pretty cumbersome unless you remove the door, hint you can not use cranes or standard systems to load new cargo. I would go for an side hinged door I think. 

Now the manned versions wee seen has an around 2 story cargo bay, and garage between the fuel part and the crew quarters. Main airlock is also here, on the schematics this has entrance to the cargo hold and an docking port, presumable so you can use the docking port as an backup if the main cargo hatch jams, having the docking port in the airlock has the extra benefit if the docking adapter get problems. 

Moonship will have an forward docking port, not sure if they keep the side one but it will also have an backup air lock, this might be an smaller one who is an backup / back door or it might using the cargo bay itself as an emergency airlock. as default its pressurized and this will be nice servicing vertices. 
Now Moonship does not need the huge crew compartment manned starship drawings as it will have an small crew. And I don't see an crew above 8-16 for an two weeks stay on the moon to be of much use anyway so probably shorter. 

[Beccab]

I still can't believe they are actually going to catch a superheavy class rocket mid-air with its launch tower. Who knows, if everything goes fine in a few years it could even seem normal

[mikegarrison]

10 hours ago, Beccab said:

I still can't believe they are actually going to catch a superheavy class rocket mid-air with its launch tower. Who knows, if everything goes fine in a few years it could even seem normal

Either it will seem normal, or it will seem like a seemingly crazy idea that turned out to be just an actually crazy idea.

Edited January 5, 2022 by mikegarrison