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.
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.
Quote from: DistantTemple on 01/15/2019 08:03 pmit 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)
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.
Quote from: JamesH65 on 01/15/2019 12:05 pmMost 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.
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.
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).
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.
Quote from: mikelepage on 01/17/2019 09:18 amI 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
Quote from: mikelepage on 01/17/2019 09:18 amI 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.
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.
Quote from: su27k on 01/17/2019 11:27 amQuote from: mikelepage on 01/17/2019 09:18 amI 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-heavyAha, I misread wikipedia. 62/22.8 seems a much more likely upscaling of energies
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!
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?
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.