Author Topic: Starship / Superheavy launch process  (Read 26689 times)

Offline RedLineTrain

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Re: Starship / Superheavy launch process
« Reply #60 on: 01/16/2019 03:01 pm »
The permutations of stainless steel compositions are pretty much endless.  Yesterday, I went down the rabbit hole of looking at stainless steel ships on the internet.  Ship hulls are not often made with stainless steel because of the additional expense versus mild steel and the corrosion at weld points.  Lots of talk that 316 L is suitable to the task.

Of course, none of the naval guys are doing "coldformed at cryo," which has the benefit of welds being as strong as the surrounding material.
« Last Edit: 01/16/2019 03:05 pm by RedLineTrain »

Offline cppetrie

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Re: Starship / Superheavy launch process
« Reply #61 on: 01/16/2019 03:05 pm »
I have a stainless steel Ruger rifle.  Used it for 10-15 years hunting in misty weather, sometimes rain, or damp weather.  I kept it taped up with camo tape to keep the shine from scaring off deer.  I also bought a stainless grill to use outside (under a porch).  In two years the grill started to show little rust spots.  So I cleaned it and put on a stainless steel polish.  It has shown no further rust.  Now, I untapped the rifle and it had no rust.  Why?  Maybe Ruger used a better stainless, or no iron in the stainless they used. 

Either way, maybe they will polish the rocket after every use to keep rust at bay.  Or use a grade that doesn't have iron in it.
If it doesn’t have iron it isn’t steel, stainless or otherwise.

Offline Johnnyhinbos

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Re: Starship / Superheavy launch process
« Reply #62 on: 01/16/2019 03:06 pm »
316 rusts. Trust me - I work with it all the time. It's subject to crevice, pit, and galvanic corrosion.
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Offline RedLineTrain

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Re: Starship / Superheavy launch process
« Reply #63 on: 01/16/2019 03:13 pm »
Have you worked with 316L and are there relevant differences versus 316?

In any event, SpaceX sounds like they are using a novel 300 series alloy.

Lots of talk that monel and aluminum were also suitable materials for ship hulls, at considerable additional expense.
« Last Edit: 01/16/2019 03:21 pm by RedLineTrain »

Offline DaveMorgan

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Re: Starship / Superheavy launch process
« Reply #64 on: 01/16/2019 03:28 pm »
it seems obvious that high quality welds (fsw etc) between 9m tube sections could be relatively easily done by rolling the tube sections. (horizontally) I'm not a manufacturing engineer, but that seems so much easier than having a circular machine hoisted 40m + up the growing body, with lots of working at height issues. I assume an fsw machine is pretty massive, and better managed at or near floor level.
Weld two bands together, then jack/crane them up and add the next band underneath while not moving the welding machine?
(e.g. start with the "top" and construct downwards)

Online envy887

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Re: Starship / Superheavy launch process
« Reply #65 on: 01/16/2019 03:37 pm »
it seems obvious that high quality welds (fsw etc) between 9m tube sections could be relatively easily done by rolling the tube sections. (horizontally) I'm not a manufacturing engineer, but that seems so much easier than having a circular machine hoisted 40m + up the growing body, with lots of working at height issues. I assume an fsw machine is pretty massive, and better managed at or near floor level.
Weld two bands together, then jack/crane them up and add the next band underneath while not moving the welding machine?
(e.g. start with the "top" and construct downwards)

Launch pads are expensive and rare (there are perhaps 3 in the US that can handle these thrust levels), while cranes and SPMTs are everywhere and cheap. Building on the pad ties up the pad for no good reason. Even if you can build it outside, it's not that hard to move a booster.

Offline Johnnyhinbos

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Re: Starship / Superheavy launch process
« Reply #66 on: 01/16/2019 03:52 pm »
Have you worked with 316L and are there relevant differences versus 316?

In any event, SpaceX sounds like they are using a novel 300 series alloy.

Lots of talk that monel and aluminum were also suitable materials for ship hulls, at considerable additional expense.
I haven't, though I believe 316L is low carbon and used in welding applications. I have had 1/2" 316 bolts snap off in my hand in salt water through crevice corrosion. The hatch in this photo completely fell off because of corroded 316 hardware. (Disclaimer - I was not actually being attacked by a Humboldt squid...)
« Last Edit: 01/16/2019 03:58 pm by Johnnyhinbos »
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Online envy887

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Re: Starship / Superheavy launch process
« Reply #67 on: 01/16/2019 04:04 pm »
Most of the stuff that will need overhauling (if any!) will be on the interior, so no need for a building for that. For the stuff that is outside, it's mostly engines, so a tent like skirt around the bottom would make that area weather proof. They could even make a mobile building that wraps around the base.

For the hull, it's stainless, so no rust, but will clearly need work occasionally, which I suspect would be done with cherry pickers and/or clamp on workshops.

Why are people still thinking stainless steel does not rust? Without maintance, 304 and 316 steel can rust easily even in kitchens, not to mention seaside launch sites.

SpaceX is probably going to use another metal or a ceramic coating over the stainless, to improve IR reflection at high temperatures. SiO2 over a few microns silver or aluminum layer, for example. This would still require maintenance and cleaning, but would not rust and would always look like "liquid silver".
« Last Edit: 01/16/2019 04:05 pm by envy887 »

Offline mikelepage

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Re: Starship / Superheavy launch process
« Reply #68 on: 01/17/2019 09:18 am »
I was thinking about noise considerations for the launch process and doing some math, comparing the figures for Falcon Heavy with that of Starship Superheavy.  I'm hoping someone can check my calculations, because it makes sense to me that if SS/SH is doing ~8x more work at launch (thrust at launch is 62 MN versus 8 MN for FH), the sound intensity ought to be ~8x higher as well.

Falcon Heavy Noise levels at launch are rated as 160 Db from 125 feet (~38m), and that would predict SS/SH noise levels to be around 178 Db at the same distance (the Decibel scale is logarithmic).

If you look at OHS limits for high noise levels, 100 Db is about as much as anyone should deal with for up to 15 minutes.  >112 Db should only occur for less than 60 seconds, if at all.

Falcon Heavy at launch breaches 100 Db if you're within about 40km.  For SS/SH, it breaches 100 Db if you're within 335km.  The 112 Db limit occurs for FH at 10km (I'm assuming that's about the size of the exclusion zone).  But the 112 Db limit occurs for SS/SH at 88km.

Implications:
1) Downtown Orlando is within 88km of KSC.  If I've calculated this correctly, then I highly doubt SS/SH will be launching from Pad 39A.
2) Better to have any platform >88km from the shoreline.  There are numerous places in the gulf (and around the world) where the depth of the water is <100m deep, even at such distances from shore.  The continental shelf near Brownsville Tx falls off at about this distance, so I expect a jack-barge/platform is the preferred option.
3) Re: PTP passenger travel, having to go nearly 100km in a ferry on either end of the trip adds multiple hours to each trip - especially if you have to get connecting service at the ferry terminal - it basically defeats the purpose of fast round the world travel. 
4) I just looked up the civilian version of the Chinook Helicopter (Boeing-Vertol model 234), which can carry 44 passengers at speeds of up to 260 km/h, with a range of about 1000km (644 mi).  Two of them landing on an offshore platform pre-launch and post-landing would greatly speed up the operation, and allow passengers to commute to the launch pad from 2 (or more) different airports.

In the early stages, I could imagine a space tourism operation operating out of Brownsville, but with Chinooks transporting passengers from Houston airport (and/or even DFW).

EDIT for interest: The continental shelf drops off about 150km South East of New York.  Any SS/SH launch from a platform there would still generate noise of 106 Db in Manhattan!
« Last Edit: 01/17/2019 09:25 am by mikelepage »

Online OneSpeed

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Re: Starship / Superheavy launch process
« Reply #69 on: 01/17/2019 11:23 am »
I was thinking about noise considerations for the launch process and doing some math, comparing the figures for Falcon Heavy with that of Starship Superheavy.  I'm hoping someone can check my calculations, because it makes sense to me that if SS/SH is doing ~8x more work at launch (thrust at launch is 62 MN versus 8 MN for FH), the sound intensity ought to be ~8x higher as well.

Falcon Heavy Noise levels at launch are rated as 160 Db from 125 feet (~38m), and that would predict SS/SH noise levels to be around 178 Db at the same distance (the Decibel scale is logarithmic).

If the increase in power is 8x, then the increase in SPL is 10 x log(8/1) = 9dB, for a total of 169 dB SPL. 178 dB SPL would require 64x the power.
« Last Edit: 01/17/2019 11:28 am by OneSpeed »

Online envy887

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Re: Starship / Superheavy launch process
« Reply #70 on: 01/17/2019 11:27 am »
The Boca Chica EIS has a definitive analysis of Falcon Heavy launch noise, and would probably be a good place to start when estimating Super Heavy launch noise.

As I recall, FH is expected to be under 100 dBa in San Padre Island, which is only 5 miles away.

Offline su27k

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Re: Starship / Superheavy launch process
« Reply #71 on: 01/17/2019 11:27 am »
I was thinking about noise considerations for the launch process and doing some math, comparing the figures for Falcon Heavy with that of Starship Superheavy.  I'm hoping someone can check my calculations, because it makes sense to me that if SS/SH is doing ~8x more work at launch (thrust at launch is 62 MN versus 8 MN for FH), the sound intensity ought to be ~8x higher as well.

7.6~8.2 MN thrust is for one core, all 3 cores of FH put out 22.8 MN of total thrust at sea level, see https://www.spacex.com/falcon-heavy

Offline testguy

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Re: Starship / Superheavy launch process
« Reply #72 on: 01/17/2019 11:45 am »
Have you worked with 316L and are there relevant differences versus 316?

In any event, SpaceX sounds like they are using a novel 300 series alloy.

Lots of talk that monel and aluminum were also suitable materials for ship hulls, at considerable additional expense.

I also have worked with 316 a lot.  316L is good for welding but shouldn't be used for high temperature applications.  I believe ASME Section 8 of the Boiler and Pressure Vessel Code limit its use to 800 F.  I don't have it in front of me.  Whereas 316 can be used up to 1500 F, and I have, of course its useful stress values drop off rapidly at higher temperatures as do all metals.

Offline mikelepage

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Re: Starship / Superheavy launch process
« Reply #73 on: 01/17/2019 12:07 pm »
I was thinking about noise considerations for the launch process and doing some math, comparing the figures for Falcon Heavy with that of Starship Superheavy.  I'm hoping someone can check my calculations, because it makes sense to me that if SS/SH is doing ~8x more work at launch (thrust at launch is 62 MN versus 8 MN for FH), the sound intensity ought to be ~8x higher as well.

7.6~8.2 MN thrust is for one core, all 3 cores of FH put out 22.8 MN of total thrust at sea level, see https://www.spacex.com/falcon-heavy

Aha, I misread wikipedia.  62/22.8 seems a much more likely upscaling of energies

I was thinking about noise considerations for the launch process and doing some math, comparing the figures for Falcon Heavy with that of Starship Superheavy.  I'm hoping someone can check my calculations, because it makes sense to me that if SS/SH is doing ~8x more work at launch (thrust at launch is 62 MN versus 8 MN for FH), the sound intensity ought to be ~8x higher as well.

Falcon Heavy Noise levels at launch are rated as 160 Db from 125 feet (~38m), and that would predict SS/SH noise levels to be around 178 Db at the same distance (the Decibel scale is logarithmic).

If the increase in power is 8x, then the increase in SPL is 10 x log(8/1) = 9dB, for a total of 169 dB SPL. 178 dB SPL would require 64x the power.

Taking the above ratio and plugging it into your formula, that suggests SH is only 4 Db louder = 164 Db (at 125 ft).  Which would suggest each of those exclusion zone (for 100 and 112 Db), for SH would be about 1.6x larger, or 16km and 64km.

The Boca Chica EIS has a definitive analysis of Falcon Heavy launch noise, and would probably be a good place to start when estimating Super Heavy launch noise.

As I recall, FH is expected to be under 100 dBa in San Padre Island, which is only 5 miles away.

The 160 Db figure I found didn't seem to include sound suppression. So 10km down to 8km (5 miles) seems reasonable.  If 20% decrease in distance for equivalent noise level is scalable, then the 16km equivalent noise zone I calculated for for SH could be as low as 12.8km :)

I made a couple mistakes, so forget what I said about pad 39A not being viable.  It looks pretty good then.


Offline rsdavis9

Re: Starship / Superheavy launch process
« Reply #74 on: 01/17/2019 12:15 pm »
If the SS is loaded with only enough fuel(and people/cargo) to hover and translate to the offshore platform...

We would only need 3 engines at low throttle setting. This should be much lower db. Fuel up on the platform. No helicopter needed. Anybody have calcs for how loud a SS is when landing?
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Online envy887

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Re: Starship / Superheavy launch process
« Reply #75 on: 01/17/2019 12:16 pm »
I was thinking about noise considerations for the launch process and doing some math, comparing the figures for Falcon Heavy with that of Starship Superheavy.  I'm hoping someone can check my calculations, because it makes sense to me that if SS/SH is doing ~8x more work at launch (thrust at launch is 62 MN versus 8 MN for FH), the sound intensity ought to be ~8x higher as well.

7.6~8.2 MN thrust is for one core, all 3 cores of FH put out 22.8 MN of total thrust at sea level, see https://www.spacex.com/falcon-heavy

Aha, I misread wikipedia.  62/22.8 seems a much more likely upscaling of energies

The 2017 BFR was shown at 5400 tonnes thrust (54 MN, based on 1750 kN per engine with 31 engines). The wikipedia number is sourced to Musk's "approximately 200 tonnes thrust" quote from the dearmoon presentation. That number seems to be the eventual thrust from a 300 bar Raptor that SpaceX is "aiming for", while the initial operational pressure was expected to be 250 bar.

I would expect closer to 54 MN, at least for initial operation of Super Heavy.

Offline Slarty1080

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Re: Starship / Superheavy launch process
« Reply #76 on: 01/17/2019 03:55 pm »
Given the San Pedro facility will no longer be used for Starship construction and that Starship will now be built at new Boca Chica facility, how practical would it be to launch a Starship/SH from Boca Chica?

Isn't Boca Chica village too close? Following the noise level comments above I would have thought that Boca Chica village would either have to be evacuated during launches or they would need to issue the residents with ear protectors, hard hats and bunkers!
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Offline philw1776

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Re: Starship / Superheavy launch process
« Reply #77 on: 01/17/2019 04:07 pm »
Given the San Pedro facility will no longer be used for Starship construction and that Starship will now be built at new Boca Chica facility, how practical would it be to launch a Starship/SH from Boca Chica?

Isn't Boca Chica village too close? Following the noise level comments above I would have thought that Boca Chica village would either have to be evacuated during launches or they would need to issue the residents with ear protectors, hard hats and bunkers!

Village too close as you say.  Even FH exceeded noise limits but allowed with free ear plugs.  As Dave reminds us the EIS needs to be applied for hearings held to launch anything large from BC.  Also the state park limits launches to weekdays only and max 12 launches per year.

New EIS requires publishing and public hearings.  Has Not happened.

My conclusion has been and continues to be that any BC SH launches take place off shore.  It's shallow for miles out.  Lower cost platforms in shallow waters.
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Offline Slarty1080

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Re: Starship / Superheavy launch process
« Reply #78 on: 01/17/2019 04:09 pm »
Have you worked with 316L and are there relevant differences versus 316?

In any event, SpaceX sounds like they are using a novel 300 series alloy.

Lots of talk that monel and aluminum were also suitable materials for ship hulls, at considerable additional expense.
We don't know what alloy SpaceX is using really do we? From the published information what can we say about its composition? As its stainless steel it must contain iron, but what about being 300 series? What does that specify? How much scope for variation is there? Is the sum information content of our knowledge reduced to just saying it’s an alloy with iron in it?

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Offline AC in NC

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Re: Starship / Superheavy launch process
« Reply #79 on: 01/17/2019 04:54 pm »
We don't know what alloy SpaceX is using really do we? From the published information what can we say about its composition? As its stainless steel it must contain iron, but what about being 300 series? What does that specify? How much scope for variation is there? Is the sum information content of our knowledge reduced to just saying it’s an alloy with iron in it?

If I had to guess, I'd say they might have gotten to something almost "boutique" in being finely tuned for purpose.

https://en.wikipedia.org/wiki/Stainless_steel#Austenitic_stainless_steel

Quote
300 Series are chromium-nickel alloys, which achieve their austenitic microstructure almost exclusively by nickel alloying, some very highly alloyed grades include some nitrogen to reduce nickel requirements. 300 series is the largest group and the most widely used. The best known grade is Type 304, also known as 18/8 and 18/10 for its composition of 18% chromium and 8%/10% nickel, respectively. The second most common austenitic stainless steel is Type 316. The addition of 2% molybdenum provides greater resistance to acids and to localized corrosion caused by chloride ions.
Low-carbon versions, for example 316L or 304L, are used to avoid corrosion problems caused by welding. The "L" means that the carbon content of the alloy is below 0.03%, which prevents sensitization (precipitation of chromium carbides at grain boundaries) caused by the high temperatures involved in welding.[citation needed]

Superaustenitic stainless steels, such as Allegheny Technologies' alloy AL-6XN and Outokumpu's alloy 254 SMO, possess even greater resistance to chloride pitting and crevice corrosion because of their high molybdenum content (>6%) and nitrogen additions. They possess useful service to seawater applications.


Some discussion of the various types of 300 here.  I'd guess we'll never hear what the recipe is but I'd guess there might be some tantalum and maybe titanium too if that's not impossible for some reason.  The trade choice on Carbon for Weldability vs. Strength looks challenging.

https://www.spiusa.com/stainlesssteel_overview.php
« Last Edit: 01/17/2019 05:17 pm by AC in NC »

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