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#26 2022-03-28 16:28:05

kbd512
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Registered: 2015-01-02
Posts: 7,607

Re: Large Ship hull material

Some mechanical engineering basics (the site contains an entire course, and this is one excerpt):

BENDING STRESS

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#27 2022-03-28 16:44:22

RobertDyck
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Re: Large Ship hull material

Corrigated core means you have a bunch of triangles. (top-left in this image)
13-Figure1-1.png

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#28 2022-03-28 19:08:48

SpaceNut
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Posts: 29,310

Re: Large Ship hull material

These are all just flavor variations of the isogrid made to give stiffness to the outer and inner sandwich that it makes.

A suspended floor above these must affix to the hull in some manner and that is to the inner layer. To make it tougher you need to multi layer or use a thick material where that point of attachment is.

pic-1.png?sfvrsn=9c798949_1

RobertDyck, remember that with each flat floor section (level) there is a gradient from being near mars gravity to if to long a value that is to much as you walk across its length.

1024px-Circularsegment.svg.png

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#29 2022-03-29 04:49:54

RobertDyck
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Re: Large Ship hull material

SpaceNut, I don't think you understand what we mean by "flat". The floor of the upper level is the ceiling of the lower level. However, it's actually a cylinder. Centre of the cylinder is centre of rotation. However, due to the large radius, it will appear flat, or mostly flat. Bulkheads will be truly flat.

Here is a website that helps: Structural performance of near-optimal sandwich panels with corrugated cores
It's interesting that the material tested in this article is stainless steel 304. Dimensions:
1-s2.0-S0020768305003665-gr1.jpg
Table 1. Geometric parameters of the two panel designs

df (mm)	dc (mm)	Hc (mm)	l (mm)	df/l	dc/l	Hc/l	θ (°)
0.635	0.25	17.5	152.4	0.00417	0.0016	0.115	45
0.635	0.25	8.4	152.4	0.00417	0.0016	0.055	45

Load orientation:
1-s2.0-S0020768305003665-gr6.jpg
Greater strength is shown in the longitudinal direction, so oriented that along the width of the wall, with transverse oriented along the height of the wall.

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#30 2022-03-29 17:49:25

SpaceNut
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Posts: 29,310

Re: Large Ship hull material

It they can be bent to shape without damaging the internal welds and be welded from both sides of the adjoining ends sure. It does come done to cost of materials and mass to make use of them and of less equipment on orbit to achieve separate piece use.

It only appears flat due to the 3' curve over a 2 meter distance of which at the 1 meter step you foot is going to making a step that is a few inches lower on the curve while the next is rising up to that cord length of 2 meters. The next level will have a shorter stride distance feeling that same effect. In time the brain will ignore it as it will feel normal as it opposite what we are doing on earth but the stride will not even notice it here unless you are rock climbing.

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#31 2022-03-29 18:05:06

RobertDyck
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Re: Large Ship hull material

The article talks about brazing, but our ship will use electron beam welding. kbd512 gave a good description of the advantages and disadvantages of laser welding vs electron beam. In space we can use either. On Earth electron beam welding is expensive because it requires a vacuum chamber, but space is the universes largest vacuum chamber. Corrugated steel can be made by either pressing a segment into a mould, or rolling. Using sheet steel to make corrugated core sandwich is easier to manufacture than cutting isogrid. We talked about using electron beam welding to apply risers to sheet steel for the outside hull. Corrugated steel sandwich looks like a good choice for bulkheads and floor/ceiling between decks.

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#32 2022-03-29 18:35:27

SpaceNut
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Re: Large Ship hull material

repost for inside the hull

I believe you are thinking about a warehouse pallet shelving system to be used inside of the hull and I think that it would start the shape so that we get the support that we are looking for internally.

Of course rather than rectangular we would be making them into 119 pie shapes.

Industrial-Shelving-Phoenix.jpg

The cross supports would go against the hull and be welded to it with the end doing the same.

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#33 2022-03-29 20:56:50

kbd512
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Re: Large Ship hull material

I recently discovered a company that offers EBW machines that establish a local coarse vacuum, such that a gigantic vacuum chamber is not required, which would drastically reduce cost and drastically increase productivity.  They say they can keep distortion to within 10% of the thickness of the part, which would mean 0.2mm for a 2mm thick C300 sheet steel.  That kind of distortion is low enough that the part could be mechanically adjusted back into shape without cracking.

EB Flow - Local Vacuum Welding

EBW is the optimal welding technique because it will produce a weld closest in strength to the base metal and has the smallest heat-affected zone for minimal heat distortion of the welded parts, and minimal changes to the mechanical properties of the metal near weld seam.  If humans or sensitive electronics are near, then laser welding is probably better, especially for thin sheet steel, because it's almost as good as EBW, can also be used for cutting, can be used inside or outside of an atmosphere, and can allow for simultaneous welding from both sides of a part in a practical manner.  EBW produces strong X-rays, so significant shielding is required if humans or electronics are in close proximity.  Basically, that means enough steel or Lead surrounding the gun or sufficient distance.

If the thickness of the welded part is 1 inch or greater, then EBW is the only practical option to avoid annealing or tempering the metal.  You can do diffusion bonding of thick metal parts, as is done in heat exchangers where even EBW is not practical due to the geometry of the parts to be bonded, but then you have to re-temper the metal, and very precisely at that.  That would be difficult to do, on-orbit.

The real issue is the pre-fabrication work done on Earth.  If you mandate the use of EBW for that, then you're resigned to slower work completion rates and higher costs.  The local vacuum EBW machine could partially or completely negate that, but the machine will be so expensive that you could purchase a dozen laser welders for less money.  However, it looks like distortion and weld speed is no better or worse than laser welding.

I'm not fixated on it, but tooling cost is an issue.  That said, scrap rates with EBW are exceptionally low and there are no consumables as is the case for laser welding, which requires an inert cover gas like Argon.

Maybe we should use laser cutters for precisely cutting the sheet metal and then use local vacuum EBW for welding, which could, at least in theory, be done within the skin of the ship during an emergency.

Anyway, there's another rather expensive issue to contend with.  Precision jigging will be very expensive.  We need an Invar or Kovar jig for these 19m long sheet metal parts.

We will lay the annealed C300 sheet into the jig (outer hull section) so it will conform to the 3mm bend under its own weight, we will weld the bulkheads / "walls" to that sheet, we will then rotate the top jig (with the work piece clamped to it and then the bottom sheet (the inner radius hull section closest to the center barrel section), lay that sheet of C300 into the jig and it will conform to that bend using its own weight, and then we will EBW the completed "doughnut slice" together, forming a rigid steel box.  If any external sheet metal stiffeners are required, then they will be welded after all internal welding has been completed, mostly to correct any distortions that fabricating the pressure compartments produces.

We're talking about big fat 19m slabs of Invar or Kovar that's precision machined and perfectly smooth.  I don't see any practical way around that, if the goal is to have these things so precisely welded that they go together like Lego bricks when they're welded together on-orbit.

Robert, I thought some more about the viability of internal composite or plastic panels to form lightweight pressure compartments, but due to the way they will have to be secured into place to resist a pressure differential from either side, I'm thinking that both assembly and repair would be more trouble than it's worth, so we're going with your welded corrugated sheet steel idea with external stiffeners that can serve as mount points for bunk beds.  Since we're talking about perfectly flat sheet, we will use local vacuum EBW to weld thin sheet together.

After all that has been done and any distortions mechanically removed (bent back into the desired shape), the annealed steel needs to be aged in a furnace to achieve full strength and hardness.  All C200/250/300/350 martensitic alloys are heated between 480°C to 510°C for 3 to 6 hours and then air cooled.  We'll be a lot closer to 3 hours than 6 hours since our sheet metal is so thin, and probably less than that.  2 hours is probably overkill, given how thin these pieces will be.

I selected the C300 alloy for the combination of its mechanical properties, which include yield, compressive yield strength, hardness, notch strength, fatigue endurance limit, excellent weldability, and good corrosion resistance.

I have selected an ion-bonded Silicon Dioxide coating to protect the base metal from atomic Oxygen, due to its proven performance as a protective coating against atomic Oxygen in LEO, abrasion resistance, excellent resistance to most dilute acids (excluding hydrofluoric acid- we really shouldn't have anything that nasty on the ship), and resistance to corrosion chloride salts dissolved in the water tanks.  SiO2 does not stand up well to strong bases like Sodium Hydroxide, so any interior space where strongly basic chemicals will be used, a different or additional coating is required.  For example, if strong bases or acids are used to adjust the pH of the water in the water tanks, then a PTFE overcoat will be necessary.

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#34 2022-03-30 11:11:55

RobertDyck
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Re: Large Ship hull material

Hmm. Pressure applies force evenly across the bulkhead. Should the longitudinal direction be oriented vertically, so it's shorter. Greater overall strength to prevent buckling.

kbd512: I know you want to make absolutely every cabin a pressure-tight compartment since that that's what the navy did. However, passenger ships have larger water-tight compartments, with walls between cabins not water-tight. I followed that same design philosophy with pressure-tight compartments. To keep weight down, cabin walls within a compartment are composite to reduce weight. That would include a steel sheet metal frame, fluoropolymer film sealed to the steel frame, and a rubber seal between steel frame and the hull. The wall frame would be bolted down tight to the hull. So a riser in the hull would have to be where the interior composite wall will go.

Back wall of the cabin is side wall of the ring. On the forward side, that's not a problem. The composite wall will be bolted to the hull the same way. Cabins with an arched ceiling, the wall will be bolted to the hull the same way again. Cabins with a "flat" ceiling, remember the ceiling isn't really flat, it's a cylinder with the centre as the centre of rotation of the ring. Cabins with a "flat" ceiling will have a room above, and use steel corrugated core. Longitudinal corrugations will be across the 19m width of the ring, with support attached to the steel bulkhead separating subcompartments. That means a plate must be welded within the core at the bulkhead so space within the corrugation does not become an air transfer path.

Attachment of composite wall to aft hull is more complicated. That's the water wall. Allowing an individual cabin to be depressurized without decompressing the rest of the subcompartment is problematic. The "end wall" of cabins will be a composite wall between cabin and water bladder. One option is to make that composite wall pressure sealed as well. This would require a pressure seal around the window frame. If a meteoroid punches through the aft wall, that creates a pressure leak through the water wall.

The more we get into details, the more I lean toward my original design. That is a whole subcompartment will decompress in case of a hull breach. Again for passenger ships, individual cabins are not water-tight.

During the space race, NASA had a problem with mass creep. Engineers kept adding things that significantly increased mass. For Gemini, NASA hired engineers from Canada, when the Avro Arrow was cancelled. That allowed American engineers to focus on the Apollo spacecraft. That sped development of Apollo because without them some American engineers would have been pulled off to work on Gemini. Gemini didn't have mass creep, the engineers were able to keep mass to original estimates. They did attempt an ambitious horizontal landing system using a Rogallo Wing, something proposed by a US air force engineer. The Rogallo Wing proved unreliable, it collapsed under load, so they had to go back to round parachutes. But my point is they avoided mass creep by not adding superfluous stuff.

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#35 2022-03-30 12:09:19

tahanson43206
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Re: Large Ship hull material

For RobertDyck ...

Thanks for your continued leadership of this important undertaking.

It is NOT time to be worried about mass creep!

You can always guide the team back to 2500 tons after we exceed it.

For the time being, nickel diming (or whatever the Canadian equivalent may be) is NOT what we need.

We need to maintain a steady pace of progress on the ** real Universe ** structure, and we do not need to go down rabbit holes based upon too-early worries about what the final total mass might  be.

We simply have NO IDEA at this point.

Safety of the passengers and crew is upper most in my mind.

We have a decent mass budget to work with.  Let's proceed to build a system that is safe and reliable and which can get  the job done first, and go back to tweak mass if we exceed the budget.

(th)

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#36 2022-03-30 12:32:43

RobertDyck
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Re: Large Ship hull material

Changing absolutely every cabin to a pressure compartment causes a lot of changes. Here is a modern cruise ship design as comparison. Notice multiple cabins within a single watertight compartment.
Watertight-subdivision-of-a-passenger-ship-with-three-examples-of-non-watertight_W640.jpg
Visualisation-of-various-typical-structures-in-the-WT-compartments-of-a-passenger-ship_W640.jpg

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#37 2022-04-02 11:49:46

kbd512
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Re: Large Ship hull material

Robert,

I'm not trying to derail your ideas or anything of that nature, so I hope you're not taking it that way.  I'm concerned about the survival of the ship's crew, nothing more than that.  Is it overkill?  Possibly.  I guess that depends upon whether or not it's your life at stake.  If you had a child, are you comfortable putting your child in this ship?  If so, then rock on.  If not, then look at it from that perspective, because that's the perspective I view it from.

My goal behind serious compartmentalization was to drastically reduce the number of people who would require evacuation or rescue if there was ever a hull penetration.  Maybe that's the wrong approach if they have sufficient life support equipment in the compartment they're trapped in, as well as serious training to use that equipment, but that was my thought process on this matter.

The most catastrophic events for ships in modern times seem to be simply running into things, not getting attacked.  Outside of WWII, vastly more ships have been sunk or scuttled after something ripped the hull open.  This is with rescue within mere hours, possibly a day or two at most, of the stricken ship.  If we trust that the whipple shield will stop all reasonably-sized objects, then maybe we can stop there.  At some point, a big enough and/or fast enough piece of debris will get through.  I'm accepting of that possibility, but then I want to minimize casualties if that happens.

Gemini was so simplistic compared to what we're doing here that the comparison isn't valid.  I get your point about eliminating superfluous features, but Mercury, Gemini, and to a lesser extent Apollo, were all experiments in spacecraft design.  Some of the things they tried didn't work out the way they wanted them to.  Yes, there's an object lesson in there for us, too.

If you're going to use larger pressure compartments, then you need more rescue equipment that's readily accessible without having to traverse a football field to get to it.  If there's a serious hull breach, then everyone involved has mere seconds to respond appropriately and accurately.  Is that realistic?  Maybe, maybe not.  It's your call.

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#38 2022-04-02 13:52:49

RobertDyck
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Re: Large Ship hull material

Your idea of rescue balls for every passenger in their bunk is a good idea. They'll have to be light, compact. Ring circumference is 236.87 metres, with a closet of emergency equipment at the base of every spoke, and 3 spokes, maximum distance is equidistant between spokes so roughly 1/6 of circumference. We could quibble about distance to a compartment pressure door. But using 1/6, that's 39.48 metres (43 yards 6 inches, or 129 feet 6 inches). Not quite half a football field.

Every kitchen will require a fire extinguisher. Modern commercial kitchens have fire suppression built into the overhead hood for the range (cooking surface). But a hand-held fire extinguisher as well is a good idea. An additional fire extinguisher in the corridor, one for every pressure subcompartment? That means a group of 8 cabins (4 on the left, 4 on the right) will have one. Or one fire extinguisher every 9.6 metres (31' 6"). CO2 fire extinguishers are rated for flammable liquids like cooking oil, as well as electrical fires. CO2 would obviously be compatible with life support on the ship.

With hull and bulkheads made of steel, and composite partition walls made of mineral wool, chance of fire is greatly reduced. But...

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#39 2022-04-02 15:13:11

kbd512
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Re: Large Ship hull material

Robert,

The use of rescue balls was NASA's idea, or someone working for them, not mine.  If you're going to have larger pressure compartments, then it makes sense to give your rescue team considerably more time to completely evacuate those compartments by ensuring that equipment is immediately available for maintaining life support in the event of a hull penetration.

It's going to take time to mount a rescue effort.  I would say that having anyone go from woken up in the middle of their "night", to fully awake, in their pressure suit, and at the scene of the affected compartment with clear instructions about what their rescue task will be, within 10 minutes, is approaching the least amount of time for a realistic response.  15 minutes is more practical.  We did general quarters drills as often as twice per day, to the point that only a few short and to-the-point commands needed to be issued, but that's about how long it took to go from sleeping to dressed-out in full FFE and awaiting DCO commands for making entry into a mainspace.  Nobody will survive a serious depressurization event for 10 to 15 minutes without their own in-compartment self-rescue equipment.  People on the other side of the ship won't immediately know what's going on or what they need to do, thus the need for assigned damage control lockers and assigned tasks during general quarters, even if that assigned task is "stay in your berthing compartment" or "round up the kiddos".

The person responding to the emergency may have to go to the spoke and then come back to the scene of the emergency.  If the emergency is in the compartment at the base of the spoke, then you really will have to cover a football field, at a minimum.  That's obviously doable, but it takes time you don't have.

Of all the likely damage control scenarios, fire is the most likely and the one most likely to result in serious non-repairable damage to the ship or shipboard systems.  Fire and smoke has the ability to kill every bit as effectively as a hard vacuum, it will weaken bulkheads and decks over time if not extinguished in a timely manner, and it will obliterate vital life support equipment and electrical cabling.  A water leak from a pipe is the second most probable, and can also cause serious damage.

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#40 2022-04-03 18:52:26

SpaceNut
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Re: Large Ship hull material

Please consider the tunnels being brought out to the full hull width of 19 meters as it will give more space and structural force capability for moving it based on the internal ribs and stringers that will be used to help in the forming and welding of the shell.

The larger tunnel will allow for a bi-direction elevator that can now have one at each end of the tunnel and switch location when one is used so as to increase safety needs.

Also consider having a third deck since we need to have tank storage below the people deck to hold water and waste making room for the plumbing and other stuff. It should adhere to the keep away zone of the first meter from the exterior wall of the hull as well.

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#41 2022-04-03 20:12:15

tahanson43206
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Re: Large Ship hull material

For SpaceNut re #40

The April 3rd Zoom just ended ... Executive Director James Burk had another meeting scheduled at the top of the hour, but this time he joined our meeting, and I got a chance to thank him (again) for providing this powerful communications technology! 

Among other outcomes for the meeting, we were joined by a rep from North Houston NSS, and a high speed exchange between GW Johnson, kbd512 and the NSS rep resolved last minute details in planning for April 9th.

This decision making process is what Zoom is perfect for.  We'd been swapping emails all week, and in a little over five minutes we got everything firmed up.

And! Before I forget ... Executive Director James Burk asked for a link to the video of Dr. Johnson's presentation, and he agreed to look for the link from you.  I will make it available to you to forward as soon as I have it, probably on Monday after April 9th.

Progress on specifying the part for fabrication of the pressure hull was not as productive as I had hoped.

The pressure hull of Large Ship is comparable to the keel of a traditional wooden ship ... it is the piece to which everything else connects, and it is the piece upon which all the living entities on board are dependent.

We made excellent progress during the meeting when RobertDyck was away.  This week, we lost ground badly, and have ended up with nothing that I can point to.

I am trying (as best I can) to move this operation from science fiction fantasy to Real Universe plans that are suitable for fund raising, and I'll keep trying, but we definitely took a hit this evening.

*** Regarding your post #40

I think your suggestion to enlarge the spokes to the full width of the habitat ring is excellent, and for the reasons you gave.  That change will increase the strength of the spoke, increase convenience for storage and personnel movement, and quite likely for other reasons we don't know about.

However, that particular battle lies ahead, because at this point, the Zoom Committee can't even agree on the nature of the hull plates.

(th)

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#42 2022-04-03 20:24:50

SpaceNut
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Re: Large Ship hull material

The keel is the first girder that has a panel that is attached to it. That girder needs to reach to the internal hub that is part of the elevator shaft or we will not have the strength for moving the structure. Its that shaft that gives the ring the strength to the central hub, that will supply the push which we must have. Its also why I suggest changing the elevator shaft dimensions to give it the strength that we need.

Use the iso grid corrugated fill of Robertdycks post as the panel connection to the girder that is 19 meters down its center. Then use the slot fit girder that heads towards the center to connect to the inner wall system that is made up the same way.

I will see whom I can find at work for structural to look at what we are doing.

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#43 2022-04-03 20:26:56

tahanson43206
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Re: Large Ship hull material

For SpaceNut .... this request/question may not be something you can address, but you may know someone who can help...

One of the issues that came up during this evening's Zoom was how best to fabricate the ribs that will run across the panels that will hold pressure.  The only thing that i can hold onto, coming out of the meeting, is a specification of 2 millimeters for the thickness of the steel plate.

The question to be addressed is how much stiffening is required to allow the pressure hull to withstand 1/2 Earth atmosphere (ie, 8 PSI). Those 8 PSI are going to be felt along the full 19 meter width of the panels after they are welded, and along the entire 238 meter length of the welded surface.

The question to be answered is: What stiffening is needed to keep the metal from bowing out under that pressure.

We don't need people walking on that surface, but the Zoom Committee hasn't even agreed on that elementary safety practice.

By any chance, do you know someone able to address this question? It is a straight engineering question.

The ribs (formers and stringers?) need to be as light as possible, suitable for welding to the steel plate of the hull, and able to withstand that 8 PSI for 50 years of service.

We started to address the issue of how to design the hull components for assembly on orbit.

One interesting suggestion was to make the hull plates out of steel that is magnetic enough to be secured by robots with magnetic pickers. That would certainly help to be able to move pieces into position for mechanical securing, and ultimately for welding.

(th)

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#44 2022-04-03 20:51:17

SpaceNut
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Re: Large Ship hull material

They are looking at the hull of the starship gauge as a reference point which is the outside thickness that needs the more robust on the inside for the area that contains the people. Welding to the trusses on the inside means that we can get away with a thinner sandwich of materials as we are welding to the support structure. The corrugated panels are welded in between the shape of the girders and that gives the compression strength that the hull needs.

The end of the stringer goes from panel to panel along the edge..think how the Ferris wheel looks...

We slide the ends of the stringer into each other and weld in place to form a solid frame around the edge as each panel is welded to the next.

The stringers take all of the mass pressure and stresses with the shell seeing less as its not the support.

The shelves that are used for pallets I can lift so while they are heavy its not that much. They support of over 1000 psi on a shelf so we have lots of strength due to spacing so it can be thinner but that is what a mechanical engineer does.

We change the shape from the L to one that has a shelf for the inner panels to drop into and weld in place looking more like T. When the panel for the inside is placed on the shelf of the T it greats the finished hull seal.

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#45 2022-04-03 21:05:40

SpaceNut
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#46 2022-04-03 21:10:08

tahanson43206
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Re: Large Ship hull material

For SpaceNut re #44

Thanks for continuing to think about this challenge!

The ribs need to be on the outside for a space craft.

They need to be on the inside for a submarine.

The surface of the pressure hull must be completely clean throughout the entire expanse of the inside of the pressure hull.

There must be no one walking on a 2 millimeter thin sheet of metal carrying 8 PSI.

If a weld fails the seam will rip from end to end. The entire spacecraft will empty within seconds.

I get the impression the members of this undertaking are not taking the matter seriously.

This undertaking started out as a science fiction fantasy.  No one (except for GW Johnson) has any experience building anything that must contain pressure.

I would like to see signs the realities of what is proposed are registering.

We have another week before the next Zoom meeting.

Hopefully we can make another tiny step forward next week.

All I have so far is:

1) length of panel: 19 meters
2) width of panel: 2 meters
3) thickness of panel: 2 millimeters
4) Material: #300 steel alloy

We have suggestions to reduce the length from 19 meters to something less for ease of stamping.

We have no answers about how to withstand 8 PSI without bowing, or pulling the sides in as the plate bows out.

All the discussion of other features of the ship are just hot air if we can't even design a simple pressure plate.

(th)

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#47 2022-04-03 21:43:03

SpaceNut
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Re: Large Ship hull material

The rib on the inside of the sub is not the hull stringer as its for implosion of pressure from the outside depth of water.

Think thermos bottle for the people hull and the casing is the outside hull with a corrugated sandwich that keeps everything together.

No one is walking on the inside paper thin hull as its not paper thin....as its a sandwich of materials stacked up....with the stiffeners in between.

The outer shell sees no pressure. The inner corrugated sees no pressure... the inner shell pushes against the stringer shelf and is welled. the floor rests on the riser step of the T center line. Each layer is staggers so that welds are not common but are over lapping to build strength.

The rib on the outside of the people tank of a Cygnus is to hang the outer shell that has the isogrid pattern in between them and it sees no air pressure...The isogrid pattern is what stops the panels from ballooning...

Take a balloon and blow it up inside a soda bottle and see once inflated that you can bow the bottle.....

We are building up strength by multiple layers.

Reducing the 19m reduces internal volume, cabin count as well as human numbers as its also reducing the greenhouse life support....

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#48 2022-04-04 06:14:01

tahanson43206
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Re: Large Ship hull material

For SpaceNut re #47

It seems you have some (or a lot) of good ideas, but they are not making there way into the Zoom discussion.

In the Zoom discussion, we have a paper thin piece of material as the hull.

There are not yet any ribs or strengtheners of any kind.

We cannot have people walking on a paper thin pressure hull, but we still have some members of the committee wanting to do that.

It would help if you were in a position to show some of your ideas with drawings, but that appears to be a future development.

We cannot have anything welded to the interior of a paper thin pressure hull, but we still have some members wanting to do that.

The group must ** somehow ** achieve the transition from science fiction fantasy to real world achievement. 

I have hope that we can make the transition, because other groups have done so in the past.

You can help if you can find examples of drawings of Real Universe space craft ... what we are focused upon right now is the pressure hull.

There are (by now) numerous (or at least several) examples of space craft able to safely hold people, and one or two are large enough to provide a useful comparison with Large Ship.

A reasonable question to ask is why the pressure hull is not toroidal in shape.  Material "wants" to form a torus under gas pressure.  Why are we trying to force the pressure hull into an unnatural cube shape? 

(th)

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#49 2022-04-04 08:07:44

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 18,142

Re: Large Ship hull material

The subject of this post is knowledge/experience/best practice for design of a pressure hull for space.

I expect to find that ALL pressure hulls for space are spherical (a) or cylindrical with dome ends (b).

However, what ** actually ** occurs remains to be revealed as we study the historical record:

Pressure Vessels in Space - ASME - The American Society of ...

www.asme.org › topics-resources › content › pressure-vessels-in-space
Dec 28, 2010 · The history of pressure vessel types has been one of gradual lightening toward that ideal. From the type I propane anvils attached to every ...

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Next-generation pressure vessels in space | CompositesWorld

www.compositesworld.com › articles › next-generation-pressure-vessels-in-...
Jul 13, 2016 · The company created a patented infinite composite pressure vessel or infiniteCPV (iCPV), which is a Type-5 (Type V), liner-less all-composite ...

nasa/sp-8083, nasa space vehicle design criteria (structures)

everyspec.com › Library › NASA › NASA-SP-PUBS

The applicable types of pressure vessels include propellant tanks ranging from main load-carrying integral tank structure to small auxiliary tanks, storage ...

(th)

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#50 2022-04-04 18:43:07

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 29,310

Re: Large Ship hull material

Yes tanks have domed ends as they are linear in length the large ship prime is not a tank and is not linear as its a loop.

The only thing that would have a dome end is due to the docking hatch which would have a dome shape to the central hub.

Tanks are also for liquid fuel to be held in that is under in this case for starship 8 atmospheric level not under 1 atm

Capsules are pressure vessels and they do not have domed surfaces....

walking along a flat ring curved surface was an issue just make it now a doughnut inner tube shape and the curve now is problematic to live in.

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