Starship all weather launch capability

[Vettedrmr]

The Russians have no problem launching Soyuz in all manner of awful weather and it has a near-flawless safety record to show for it.  Surely it can't be impossible if they're doing it.

Not really.  They launch in rain and snow, but they still don't launch in electrical storm conditions (which don't happen much at those latitudes).  Florida, OTOH, is the thunderstorm capital of the world.

[Jim]

To sound out your expert knowledge, do you believe Soyuz to have the lowest constraints for a liquid fueled launcher currently operated however? What would you feel is the origin of those lower constraints? Or as you imply, it's merely luck that Baikonur has low weather violation probability and as such Soyuz is just lucky in that regard and it doesn't actually have a substantial poor weather capability margin over other launcher/spaceport combos?

It can handle cold weather because it was designed for cold weather. 

Baikonur is in a desert (annual precipitation 5 in) so it doesn't get the rain and storms like Florida. 

The vehicle is fairly robust structurally, but I have no idea about winds aloft in Baikonur.

[Jim]

I'd love to understand more about, for example, high-level wind shear, what could be done to better cope with (not avoid) it, and what the penalties of those mitigations would be.

reduce structural margins - increases risk of structural failure

increase vehicle structural strength -  reduces payload

decrease length/diameter ratio

[edzieba]

Wind shear tolerance: lower fineness ratio, stronger structure.

Lightning: Lightning hardening of electronics (Starship is already even better shielded than your average aluminium-skinned aircraft due to its thicker skin with a higher melting point, and those are struck on average once per year) and ensuring skin heating from an estimated maximum energy lightning strike is not sufficient to cause a tank to fail.
There is also the Soyuz stuck by lightning during a GLONASS launch to no ill effect:

Ground level winds: As long as the wind direction is not pushing the vehicle into the support tower, and the supper surface of the launch platform is free from protrusions, then avionics programming to allow the vehicle to stably 'crab' sideways during the initial ascent determines the tolerance to ground wind speed and gusts.

Freezing rain and ice: A tough one. Full enclosure of the vehicle is likely not feasible (not without your enclosure being unintentionally single use), but similar insulation mats to those seen on Soyuz and Proton during transport, that can be removed remotely immediately before launch, could keep ice buildup on the vehicle itself to a minimum - at least for the first launch attempt of the day. This in particular is going to be the hardest problem for Starship, as it has the double-whammie of externally exposed mechanisms (flap actuation) and exposed hygroscopic TPS, both of which could be rendered inoperable by ice buildup. Superheavy has the gridfins, which would also be exposed to the same issue.

For the offshore platforms, sea-state is going to be the bigger problem. Not just for platform stability during launch, but for all the other operations prior to them (hooking up to propellant supply tankers, transferring personnel on and off, hoisting payload onto the platform for integration, etc).

[Jim]

Ground level winds: As long as the wind direction is not pushing the vehicle into the support tower, and the supper surface of the launch platform is free from protrusions, then avionics programming to allow the vehicle to stably 'crab' sideways during the initial ascent determines the tolerance to ground wind speed and gusts.

There are also exhaust impingement issues that have to be taken into account.

[cuddihy]

Does a wider Superheavy with same Starship help in this regard? In another thread there was speculation that going to an 18m superheavy reduces the volume required height of the superheavy to (pi/4)  ratio of original superheavy height, although increased wall & end bulkhead thickness/ SH->SS transition adaptor/increased structural mass probably cuts it to ~1/4 reduction -- so reduction from 70 m ~ 50m for superheavy, making Starship & Superheavy about the same height & the stack 20m shorter.

fineness ratio goes from 120/9 = 13.3 currently to 100/18 = 5.6  (help me out engineers, did I calculate that right?)

That's got to help on windshear resistance, right?

*edit* not saying this is going to happen for obvious tooling, process, and material reasons, just asking if it would help for all-weather, particularly windshear resistance.

[Barnalby]

SpaceX loves its pencil boosters though.  Sometimes I wonder if they poached someone from the Zenit design team back in the 2000s.

[steveleach]

Freezing rain and ice: A tough one. Full enclosure of the vehicle is likely not feasible (not without your enclosure being unintentionally single use), but similar insulation mats to those seen on Soyuz and Proton during transport, that can be removed remotely immediately before launch, could keep ice buildup on the vehicle itself to a minimum - at least for the first launch attempt of the day. This in particular is going to be the hardest problem for Starship, as it has the double-whammie of externally exposed mechanisms (flap actuation) and exposed hygroscopic TPS, both of which could be rendered inoperable by ice buildup. Superheavy has the gridfins, which would also be exposed to the same issue.

Would the kind of de-icing spray that we see used on commercial passenger jets be of any use for this sort of thing?

And even discounting freezing, how would the felt backing (or whatever it is) behind the TPS cope with getting wet? Presumably that's something they are already dealing with.

[Jim]

Would the kind of de-icing spray that we see used on commercial passenger jets be of any use for this sort of thing?

No.  Too cold, it would add to the ice

[steveleach]

Would the kind of de-icing spray that we see used on commercial passenger jets be of any use for this sort of thing?

No.  Too cold, it would add to the ice

You mean because of the combination of the subcooled propellant and the ambient temperature?

I'm still trying to get my head around the problems of 250k vs 300k air temperature in the immediate vicinity of 100k LOX tanks.

[edzieba]

Would the kind of de-icing spray that we see used on commercial passenger jets be of any use for this sort of thing?

No.  Too cold, it would add to the ice

You mean because of the combination of the subcooled propellant and the ambient temperature?

I'm still trying to get my head around the problems of 250k vs 300k air temperature in the immediate vicinity of 100k LOX tanks.

Add external insulation, shorten time the cryogens are in the uninsulated tanks (load late, load fast), or flood the local atmosphere with dry Nitrogen (not feasible for non-silo launches).

[Jim]

Would the kind of de-icing spray that we see used on commercial passenger jets be of any use for this sort of thing?

No.  Too cold, it would add to the ice

You mean because of the combination of the subcooled propellant and the ambient temperature?

I'm still trying to get my head around the problems of 250k vs 300k air temperature in the immediate vicinity of 100k LOX tanks.

Methane is just as cold. 

Deicing fluid lowest freezing point is -60C.  That is 100 degrees warmer than the propellants.

[Jim]

Add external insulation,

with increased maintenance and turnaround time

[steveleach]

Would the kind of de-icing spray that we see used on commercial passenger jets be of any use for this sort of thing?

No.  Too cold, it would add to the ice

You mean because of the combination of the subcooled propellant and the ambient temperature?

I'm still trying to get my head around the problems of 250k vs 300k air temperature in the immediate vicinity of 100k LOX tanks.

Methane is just as cold. 

Deicing fluid lowest freezing point is -60C.  That is 100 degrees warmer than the propellants.

That makes sense, but just leaves me wondering why cold weather would be a problem at all. They already have to deal with temperatures much colder than anything the weather might throw at them.

[Jim]

That makes sense, but just leaves me wondering why cold weather would be a problem at all. They already have to deal with temperatures much colder than anything the weather might throw at them.

Because the rest of the hardware doesn't like it. The payload, avionics, cabling, GSE and other system. 

Engine compartments, interstages, avionics compartments are purged with warm gas during launch.  But not during all ops and there is risk of water condensation. 

Russians use sealed pressurized containers for their electronics

[cuddihy]

Russians use sealed pressurized containers for their electronics

Given the mass budget would expect SpaceX to do the same with Starship. Also although I can't find it now I remember a detailed interview with the SpaceX avionics team about F1/F9 from 8-10 years ago. They were pressure sealing avionics at the time. Did that change during F9 development?

Do we have any evidence the avionics are not in pressurized containers?

[Jim]

Russians use sealed pressurized containers for their electronics

Given the mass budget would expect SpaceX to do the same with Starship. Also although I can't find it now I remember a detailed interview with the SpaceX avionics team about F1/F9 from 8-10 years ago. They were pressure sealing avionics at the time. Did that change during F9 development?

Do we have any evidence the avionics are not in pressurized containers?

https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=37476.0;attach=1036642;image

[Jim]

Given the mass budget would expect SpaceX to do the same with Starship.

No, not the same. 

This is what is meant by sealed pressurized containers.

https://www.esa.int/var/esa/storage/images/esa_multimedia/images/2003/04/fregat_upper_stage_diagram/9791890-3-eng-GB/Fregat_upper_stage_diagram_pillars.jpg

[cuddihy]

Russians use sealed pressurized containers for their electronics

Given the mass budget would expect SpaceX to do the same with Starship. Also although I can't find it now I remember a detailed interview with the SpaceX avionics team about F1/F9 from 8-10 years ago. They were pressure sealing avionics at the time. Did that change during F9 development?

Do we have any evidence the avionics are not in pressurized containers?

https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=37476.0;attach=1036642;image

You must have access to a photo with resolution sufficient to tell detail that I can't see there...I definitely take your word for it that F9 avionics are not currently in pressurized containers. (Wow, not even boxes for the computers?)

Surely that will be corrected with Starship.

[Jim]

Surely that will be corrected with Starship.

why?  How are you going to cool them?