Large Ship (Prime) Bill of Material / Mass Allocation

tahanson43206 · 2022-03-21 07:44:43

Out of necessity, this topic is intended to carry items intended for assembly of Large Ship (Prime)

When alternative designs begin to look achievable, they can initiate their own BOM topic.

The (arbitrary) mass allocation for Large Ship (Prime) is 5000 tons. That is a figure chosen by GW Johnson for calculation of quantities of propellant and methods of propulsion, to move Large Ship from LEO to LMO and back to LEO.

An upper figure of 2,000,000 metric tons of propellant appears to be a figure that flows from a flight plan using chemical propellant and no assistance from space tugs at either end of the flight.

Alternative flight plans appear to have the potential to reduce propellant requirements somewhat.

The most attractive alternate flight plan would use space tugs at both ends of the trip, for both departure and arrival.

The Large Ship needs to stay within it's mass budget, whatever that budget turns out to be.

The concept for this new topic is to identify, to quantify and to characterize components.

(th)

tahanson43206 · 2022-03-21 07:56:30

The lead off component for Large Ship (Prime) is hull plating...

The Zoom meeting of 2022/03/20 produced as one of several outputs, a ** real live decision ** ...

The hull plates to carry pressure below the passenger cabins are to be fashioned on Earth and shipped to LEO for welding to Large Ship.

The length of the plates is 19 meters, which fits inside the Starship freight compartment.

The width of the plates is not yet determined, but it is a combination of these factors:

1) A set of these plates will weld together to create a seamless layer of metal 238 meters in length (circumference of habitat ring)

2) The width is less than whatever maximum value is allowed by the Starship freight compartment

3) The configuration of the plates is suggested to be [term to be added] flat sections with ridges raised for strength.

Note: It is NOT necessary for the plates to be curved. Curvature of the hull can be achieved by welding the plates at the required angle.

For example, if the plates are 1 meter wide, then the weld would be performed so that two adjacent plates are 360/238 degrees with respect to each other.

Welding may be either Electron Beam Welding or Laser Welding.

Todo Items for members of the forum:

1) List structural elements of large aircraft fuselage
2) Show suitability (or not) for given structural elements for Large Ship

Please keep ** this ** topic reserved for components agreed upon by the Zoom committee.

Discussion can take place in Large Ship (Prime) topic.

Policy for Updates as Revisions arrive:

This BOM item is incomplete. The only firm configuration element is the length of the plates (19 meters)

As decisions are made, the intention is to update ** this ** post.

SearchTerm:Plates Hull Pressure Large Ship (Prime)
SearchTerm:Hull Plates Pressure

(th)

SpaceNut · 2022-03-22 19:13:29

We do not bend welded plate as that will cause micro fractures to occur of thin to modestly thick joints. Bends for the ring curve must happen in a fixture that bends and aligns the panels for a small seem to be done while the plates are held tightly in place after getting them true plus flush so that we do not have issues with the final weld of the section before moving to the next. The welded panels are then released and the next panel is feed into the device to be bent and moved to the seem so that it can be robotic-ally welded to the last until we are at the last to be done.

A different fixture would be used to hold and cut the panels for the top and bottom portions of the ring to allow for fitting them so as to not have gaps at the seem.
The inner bulkheads and floors that run would be affixed with channels attached to the outer and inner walls to give extra support.

weld joint types pic-1.png?sfvrsn=9c798949_1

Once we get a good portion of the ring started a second machine would shape and weld the iso-grid panels to give the metal stiffness. The seems for each layer are staggered so as to not allow for weld build up in a single location and weakness to happen.

The affixing of the inner hull plates are a different type of weld or assembly so as to give the finned surface for the interior of the ship.

The Starships cargo dock is a LIDS size or that of the Dragon Cargo and that is about a 4' x 4' opening to shove the panels into and the diameter of the spaceship cargo is just 9 m wide.

Until the space x ship is designed with a shuttle like cargo door assembly we are going to have issues with large plates.

tahanson43206 · 2022-03-22 19:26:27

For SpaceNut re #3

Thanks for helping to start adding to this new topic...

The construction advice you've provided seems (to me at least) to be a good fit for a topic about construction of large ship, if we have one.

This topic will (hopefully) contain specifications for particular items that will be given dimensions, materials specifications, special shapes as needed for their function, and precise mass amounts.

You've identified a number of items that look like they'd be needed.

Those need to pass through the decision making process (a Zoom meeting), and then entered into this topic as vetted components.

At this point, I don't think anyone has a clear idea how the panels decided upon at the last Zoom meeting will be held in position.

If you take a look at the Large Ship (Prime) topic, you'll see the beginnings of the thought process that will (hopefully) lead to component specification.

(th)

SpaceNut · 2022-03-22 19:51:44

The large ship ring corners joint (top ring to outer shell) would use a half edge as it needs a ring support rim just recessed below the lip top as to allow for the outer weld to hold more than one piece to the outer shell.

The construction technique will be different from the Cygnus vehicle as we will need to do it in space where the tools will need a support platform that can move to areas that men would normally work within.

I am thinking that we will needs a small self powered unit to move about the ship as its being constructed to give additional data of its construction as it takes shape.

The real BOM starts with what you put into the ship once the hull is complete for manned transfer and affixing to the ship for use.

tahanson43206 · 2022-03-22 21:08:06

For SpaceNut ... neat image in Post #4...

You may be able to clarify the concept of Bill of Material for a ship .... I'm not talking about any ship you might have personal knowledge of ...

However, I get the impression you may (possibly) know what components are brought together to make a ship ... any ship, but preferably a large one.

Your phrasing in the closing line is dismissive of the keel, and the major components of the hull.

Did you intend to dismiss the hull components as unworthy of your attention? It almost seems as though you regard furniture as more important than a building.

Hopefully that is not what you meant to imply.

I have opened this topic so that RobertDyck's support team will be able to identify each and every component needed to assemble Large Ship in LEO.

I opened the topic with the only piece of metal that has come out of the Zoom meetings to this point.

Your anticipation of furniture is getting the cart well ahead of the horse.

We can only work with what RobertDyck delivers to work with.

To this point he has produced hundreds if not thousands of posts covering almost as many aspects of the vision, but only ONE single part has come out of all that thinking and discussion.

Let's focus on the one part that we have in hand.

Those hull plates need to be welded to components that I ** think ** are called "formers" and "stringers"

We need for the formers and stringers to be defined. We need dimensions, materials, mass and probably other measurements I don't know about.

Bill of Materials (BOM) Definition - Investopedia
www.investopedia.com › Corporate Finance & Accounting › Accounting
A bill of materials (BOM) is a centralized source of information used to manufacture a product. It is a list of the items needed to create a product as well as ...

The Bill of Materials for Large Ship will include thousands of items. Because every gram must be justified, every gram will have won its way into the list.

However, so items in the BOM are dependent upon others.

A BOM for an automobile would customarily start with the chassis .. in Ford's day that was an assembly of metal upon which all the rest of the components were hung. Now-a-days, with unibody construction, it is the components of the body that are assembled and welded together, but all those components started out as unique shapes that ended up combined into that unibody.

(th)

tahanson43206 · 2022-03-22 21:49:12

Want to customize your bill of materials? Show Customization Options
BILL OF MATERIALS
From NewMars Large Ship Committee

Product
Product name
Other product information
For
Vendor name
Vendor address
B.O.M. #
0000001
Date
03/23/2022
Part # Name Quantity Unit Price Part Cost

0.00
0.00
0.00
0.00
0.00
0.00
Notes
Part count
0.00

Total Cost
0.00

This example is from a company that offers a computer based Bill of Material service

What I'm looking for for in this topic is more than just a name of an item and a price ...

What I'm looking for is identification of the part, measurements pertinent to procurement and it's relationship to the Large Ship.

Every part will be part of something larger, and all assemblies will ultimately form the Large Ship.

The Habitat Ring is a major subsystem, as is the Central Hub.

Support structure include braces to carry force from the Central Hub to the Habitat Ring (and the reverse of course).

The Radiation Protection system is external to all other components.

The meteor protection and temperature regulation system is between the Radiation Protection system and the Habitat Ring.

A Modular Propulsion System is supported by propellant tanks.

All components are mounted so as to preserve mass symmetry throughout the vessel, since it is to rotate at 3 RPM.

(th)

RobertDyck · 2022-03-22 23:45:42

Star Trek "The Motion Picture", travel pod...

Star Trek TNG, worker bees...
Mark%2BKrentz%2BStar%2BTrek%2BDiscovery%2Bworker%2Bbee.jpg

2001: A Space Odyssey, pod...

From real life. NASA's AERCam Spirit, image taken during STS-87 December 10, 1997...

Japanese camera drone for use inside ISS, called JEM Internal Ball Camera or Int-Ball delivered aboard SpaceX CRS-11 on June 4, 2017...

tahanson43206 · 2022-03-23 06:19:09

For RobertDyck, kbd512 and SpaceNut ...

This topic is set up to allow focus on parts to be incorporated in Large Ship...

Discussion of construction techniques is appropriate in a topic dedicated to discussion of discussion techniques.

At this point, we only have ONE part identified, and it's definition is incomplete.

We have a hull plate for the pressure hull outside the cabin space in the Habitat Ring.

We have ONLY the length! 19 meters

We do NOT have the width (must be small enough to stack in a Starship freight carrier.

We do NOT have the thickness.

We do NOT have the specification for ribbing, if any.

We DO have a decision not to curve the plates. Curvature can be achieved by welding the long sides of the plates at a small angle over 238 meters.

We do NOT have a specification for the material to be used, and for the manufacturing process to yield desired qualities.

I'd like to see this ONE single part defined fully.

I'd like to see at least ONE more part added to the design each week. There are thousands of parts needed to build this vessel.

(th)

tahanson43206 · 2022-03-23 06:29:36

For RobertDyck, kbd512 and SpaceNut ....

It turns out we ** have ** a topic dedicated to assembly on orbit.

Large Ship Assembly and Checkout on Orbit by tahanson43206
Interplanetary transportation 7 2022-03-20 17:47:30 by SpaceNut

Please keep this topic focused tightly on individual parts and assemblies of those parts.

There are many Bill of Materials data base designs, and if necessary one can be created.

However, at present we only have ONE partially defined part for a system that will contain thousands of parts.

I'd like to see at least one part or assembly defined per week.

(th)

RobertDyck · 2022-03-23 12:29:52

One difficulty is we have a fundamental disagreement. I want to harvest a metal asteroid for hull material. That includes the micrometeoroid shield, pressure hull, bulkheads, pressure doors (hatches). Harvest lunar regolith to smelt into aluminum, then produce aluminum oxynitride for windows. Radiators use inconel pipes, but radiator fins are aluminum alloy. Metal asteroids include nickel and chrome, the Moon has aluminum.

One of the points of this are hull plates do not have to fit within a SpaceX Starship fairing if they aren't launched from Earth.

NASA: International Space Station (ISS) Heat Rejection Subsystem (HRS) Radiator Face Sheet Damage

The tube spacing is closer near the panel center to prevent ammonia freezing due to the higher head load density in the radiator panel. The 0.125-inch Inconel® 718 tubes have a wall thickness of 0.029 inches and are individually proof tested to 39,000 psig for freeze tolerance. Each tube is encased in an aluminum extrusion that is epoxy-bonded to both face sheets. Within each extrusion, the tube is bonded using silver-filled epoxy to maximize heat transfer as shown in Figures 5.1-6 and 5.1-7.

Images on page numbered 20, but page 24 in the PDF. They didn't number the title pages.

From a company called Special Metals: Inconel alloy 718 Missing are rare earth metals: neobium and tantalum.

Nickel (plus Cobalt) .......................................................50.00-55.00
Chromium......................................................................17.00-21.00
Iron .....................................................................................Balance*
Niobium (plus Tantalum)....................................................4.75-5.50
Molybdenum .....................................................................2.80-3.30
Titanium.............................................................................0.65-1.15
Aluminum ..........................................................................0.20-0.80
Cobalt ...............................................................................1.00 max.
Carbon ..............................................................................0.08 max.
Manganese .......................................................................0.35 max.
Silicon ...............................................................................0.35 max.
Phosphorus.....................................................................0.015 max.
Sulfur...............................................................................0.015 max.
Boron ..............................................................................0.006 max.
Copper..............................................................................0.30 max.

Note: anything that says "max" is not required, but allowed. This means required metals are nickel, chromium, iron, nobium, molybdenum, titanium, aluminum. Metal asteroids are mostly iron, with significant nickel. I treat meteorites as a reasonable sample of Near Earth Objects, if something contains more than 0.05% chrome, it isn't a meteorite. This requires going through a lot of asteroid metal to get enough chrome. The Moon has a lot of aluminum and a little titanium.

Here's an average calculation of group IVB iron meteorites:

SpaceNut · 2022-03-23 18:56:31

Many of the raw ore sources are with some expenditure even if it takes less fuel for it to be mode and processed its still a delay in beginning the building process. It also adds to the initial upfront costs to get so that we can utilize these resources.

This is where a trade study comes in once you have the estimate BOM to make use of for what you want to build.

Along with the resource you need to understand the equipment and not just how to make use of the raw to finished materials for the construction.

I gave an estimate of what we need for each combined section covering the use of an outer shell of stainless steel, aluminum isogrid stiffener and more stainless steel.

480 mT ring materials
120 mT tunnels x 3
+160 mT main hub
--------
760 mT

I would shoot for a rough 1,000 mT of supplied materials to finish up making it sealed

If we use the cygnus as the construction technique the isogrid material is welded to the curved welded inner and outer of the stainless steel.

This one is a solid milled but we can also use a stamped pressed version of the isogrid to weld with as well and the sections are staggered so that seams are not at the same point.

?url=http:%2F%2Fnewatlas-brightspot.s3.amazonaws.com%2Farchive%2Forbital-crs-6-launch-6.jpg

Notice that the outer stainless steel is not welded but makes use of fastener hardware.

Now once we get the inner shell air lock and decks inside which are the only angled welds from the inner to outer ring hull wall.

Do not forget that once we get the hull complete we are using sacrifice blankets to aid in the hulls protection that will be added to the outside surface.

Now that we can dock a ship to the central hub we are able to move the interior content in shirt sleeves. This includes the plumbing, wiring ect to start creating rooms and habitat spaces.

Not having a room count, number of outlets, switches for each room to be constructed means we need to guess on the mass and length as well as the possible counts of the electrical stuff to be brought up to build with.

The food court areas which have the kitchens, freezers, refrigeration also are another unknown as we need to count up the circuits for each power levels and plug type which will be required.

We also need a final determination of shower and water locations to be plumbed so that a drain system can be mapped as well. Of course this feeds holding tanks for the recovery process and waste management section.

The we move onto the food garden location of the ship so that we supply what it needs as well.

Last items are for safety and emergency use locker and systems to ensure we have a safe journey with the proper collective of apparatus for these events.

We will also need to do drills to ensure people know what to do in case of one.

tahanson43206 · 2022-03-24 08:49:50

For SpaceNut ... thank you for Post #12

The images of a space craft that exists and is in service is helpful.

The many suggestions for activities to be carried out is also helpful, but it does not fit naturally in a topic devoted to specific items to be assembled to create (some version of) Large Ship in LEO.

All we have right now is a single firmly defined part, and even ** it ** is incomplete.

Your suggestions for activities to be carried out are important and needed, and they should be posted in a topic devoted to tasks ...

Such a topic might have a title like "Large Ship Task List"

If anyone has the time, the energy, and above all, the ability to focus, I am asking/calling for completion of the specifications for the one part we have in work.

We can build the entire Large Ship with that single part as the foundation element.

A Blender drawing of that ONE part, replicated as many times as necessary, would be a valuable addition to THIS topic.

Reminder to all ... the pressure hull is NOT a walk-on floor of a cabin.

Therefore, the size of the pressure hull circumference should be increased so that the cabin floor is able to reside at the 238 meter circumference called for by RobertDyck in his stone tablets.

GW Johnson recommends there be enough space between the floor of the cabins, and the pressure hull, so that a human being encumbered with a space suit can locate an impact site.

It has been suggested that floor panels in the cabins and in the corridors might be a substitute way of accessing the pressure hull.

This idea is interesting, and it may have merit.

However, I recommend not putting holes in the cabin floor, because it needs to be able to hold pressure if the entire Habitat ring loses pressure.

If the hole to be patched is under a cabin with people being protected by pressure in the cabin, then it is not practical to lift a panel in the cabin floor.

Furthermore, adding a set of panels to the cabin floor vastly increases the cost and mass of the cabin floor.

This entire post (most likely) belongs in another topic.

(th)

tahanson43206 · 2022-03-24 09:10:00

The focus of ** this ** post is Open Source Bill of Materials software, including specific database designs/templates that may exist.

It appears that the Linux Foundation is offering a class for a software Bill of Materials ... While I have not encountered that concept in commercial practice, it certainly makes sense as part of the documentation of a software system.

Developer Tools provide what amounts to the same information, when asked to show where a particular module is used in a large system.

The Linux Foundation training page on Software BOM gives reasons why such a set of data might be helpful to a manager of a large system.

The issue that caught my eye in particular is the licensing of components blended into a large project. Each component has a license agreement that may derive from the one for the project itself, or may have an entirely different lineage. In any case, the manager is at risk if the license agreement situation is unknown. Most of us computer users just accept the risks of using free software because we don't have a lot of choice.

In the case of Large Ship, I think the example of NASA is instructive.

Every part that goes into a NASA vehicle/probe/whatever is tracked on an individual basis.

Because of the life-or-death nature of the Large Ship project, I think it is well worth implementing that exact same procedure for every part that goes into the vessel. Most of such tracking can be (and should be) automated.

When an inspection on orbit, or in flight, reveals that a particular part has failed prematurely, it will be possible to examine the history of that specific part all the way back to the garage where someone moonlighting turned it out on a lathe.

(th)

RobertDyck · 2022-03-24 09:39:43

Be very very careful. Detailed records are kept of commercial jet airliners: every repair, every bolt. However, paperwork for Space Shuttle was so extreme that technicians had to do 6 hours of paperwork for 1/2 an hour of actual work. A manager said if the paper for a single launch were stacked it would be taller than the Shuttle launch stack. NASA administrators desired to reduce the paperwork to equal that of commercial jet airliners. So I think you should use airliners as an example, not NASA.

tahanson43206 · 2022-03-24 09:46:44

For RobertDyck re #15

Your opening line says it all!

Be very very careful.

Now you know, and ** I ** know that you did not intend this as advice for workers building Large Ship.

However, ** I ** am glad to see your opening words, because ** I ** hope they will be taken to heart by everyone working on this vessel, regardless of their position in the hierarchy.

Automation of record keeping is possible today, which was NOT the case when the Space Shuttle was built.

Your insurance company will be liable for every life lost on board a vessel you have built and for which you have accepted responsibility.

Your insurance company, therefore, will expect ** you ** to exercise every possible precaution against accidental error. The insurance company will not expect you to prevent willful damage to any part of Large Ship, but it ** will ** expect you do do the proper diligence in hiring, and in giving any person access to the ship itself, or to any component of the ship.

So! Your opening line deserves to stand as a mantra!

Be very very careful.

(th)

SpaceNut · 2022-03-24 20:26:29

A list of what you think is required for the building of a large ship will fall short of every goal required as you also need to know the equipment you will need, the processes you will use and where each piece will need to go. With out these its just a pile of crap setting on the ground with no means to do anything with it.

Large Ship (Prime) is designed/intended to carry 1000 passengers and 60 crew members safely

The large ship has people and yet we have no working limits as to how many are men, women or children that will be onboard.
Each has different needs in dietary, square footage to stay sane, places to sleep, places to play if you are a kid.

1. So easy list how many sleeping mattress sizes you need to cover what quantity of each, how much mass they are each, what types of frames will be used to support them plus mass, how they are attached to keep them in place until the ship is under way and rotating. Just how many quarters are there to be and what foot print let alone the arrangement around the ships interior. Then what are the sleeping bag locations for micro-gravity until they get to be used as the numbers if personnel are ramped up.

2. how many dishes, silverware, pots or pans, drinking glass or cups, ect will we need to cover all use for a 24/7 operation?

3. logistical plan for health of all that board and what it will take to keep them all in good health.

We are doing more than bringing our home and way of life with us to mars as we have an empty ship to start with.

tahanson43206 · 2022-03-25 05:26:49

For SpaceNut ... your post #17 is packed with (what come across to me as) good ideas for the project taken as a whole.

However, from my perspective, it seems to me that you are putting the cart about six blocks in front of the horse.

If you were planning the materials to build a house, or a shed for that matter, you would NOT be thinking about pots and pans for the kitchen.

You wouldn't even be thinking about cupboards for the kitchen.

Long before you would think about such things, (I would ** hope **) you would be thinking about the foundation, the frame, the roof, the walls and flooring. You might then begin to think about flooring.

However, as I try to follow your lead here, I find myself trying to imagine the uses to which the enclosed volume would be put.

Pondering a bit further... the writing in your post reminds me of what (I imagine) would be in the mind of an architect with a commission to build a home for a family on a particular lot. The shape of the home might be a cookie cutter from a pile of previously designed homes, or it might be designed in a unique manner adapted to the lot and to the family, and perhaps to the neighborhood.

In this case, we have a fundamental constraint that is (roughly) equivalent to the lot.

The circular shape of the habitat ring is predefined as a customer requirement.

The number of passengers and crew are defined, as you noted.

The rotation rate is defined, and it will not be changed, so the consequences of operating a rotating system must be accepted.

Those consequences include precision in mass distribution, and avoidance of out-of-round conditions caused by movement of mass inside the vessel during operation.

There is an opportunity here for Division of Labor ... if a member of the family would like to work on pot and pan selection, the architect can work on designing the foundation, the framing, the roof, the walls and such other essential components as are needed to support the user population as PERMANENT fixtures.

Pots and pans are going to come and go over the life of the structure. The roof will need maintenance, as well other parts of the structure.

Space for the pots and pans, on the other hand, is a permanent feature of the structure.

I find myself coming around to liking your suggestion, and now wondering how to incorporate visualizing the end state (happy people) into the Bill of Material database.

Planning for the health of the crew and passengers is important as well, but it is a very small part of a Bill of Material database.

On the other hand, I take your point that space is needed for storage of medical equipment and supplies.

Please consider moving your design conversation out of Bill of Material.

In future, please consider using Bill of Material to hold specific items you want to see included in the planning for Large Ship (Prime).

It may very well turn out that a topic devoted to architecture of large Ship (Prime) needs it's own topic.

It may even turn out that we already have such a topic ... the Large Ship (Prime) topic is perfect for contributions such as yours.

The manager of that topic may reveal preconceived notions that differ from your suggestions, but I think it is helpful to everyone to have your suggestions considered.

(th)

kbd512 · 2022-03-25 12:11:59

Does anyone else understand that using a material like 304 stainless steel is the entire reason why an isogrid pattern has to be carved into the plating to begin with?

304 is so soft and the yield strength so low that it mandates special machining and fabrication techniques to make it strong enough to withstand the tensile forces applied to it. Most of the super alloys are worse, in that regard. They can be made much stronger, but only by significantly sacrificing on other important mechanical properties like notch strength or toughness (the ability to smack the crap out of the metal and not shear or crack it).

The 625 Inconel bolts and studs that ARP manufactures are great at withstanding tensile forces applied in one direction, but if you were to accidentally smack a head stud connecting the head to the engine block, then the bolt would likely shear. It's great for that specific use case, namely keeping the heads connected to the engine block in high-heat / high-horsepower applications, but it would be a terrible material choice for a crankshaft or a main cap. It might be okay for a camshaft, but it would be absurdly expensive and tool steel is still much harder and tougher. These 625 Inconel parts also go through numerous heat treatment cycles to give them the mechanical properties that ARP is after.

Here's an interesting tidbit from ARP on their 304 stainless fasteners:

12. What does a “stainless steel” atom arrangement look like? How many atoms?
A face centered cubic arrangement of atoms Stainless Steel 300 series is not heat-treatable. But heavy reduction (power dumping), in the cross section, during forging causes a dramatic increase in strength. This is the process ARP uses to make 304 Stainless Steel reach 170,000 psi UTS.
...
17. Define “Power Dump.”
This is a term used to define the heavy extrusion of the fastener body during forging. The part is forced into a die much smaller than the blank thereby causing a severe reduction in cross section area. This reduction of the cross sectional area is accompanied by an increase in length because metals can’t be compressed. However, power dumping or reduction, delivers a significant increase in strength properties and is part of the patented process we use to produce fasteners from 304 stainless steel with 170,000 psi UTS and AMS 5844 (ARP 3.5) with ultimate tensile strengths in the 270,000 psi UTS range with outstanding fatigue.
...
19. What exactly is ARP2000 and how does it compare to 8740 and 4340?
ARP2000 is a heavily alloyed martensitic quench and temper steel, initially developed for use in steam power plants. As such it has excellent stability at high temperatures. But most important, ARP research discovered that in addition to temperature stability it has excellent notch toughness in the higher strength ranges and is alloyed to be tempered to Rc44/47. 8740 and 4340 can be tempered to the same hardness. But, the tempering temperature would yield material in the “temper brittle zone” (between 500° and 700°F), producing significant notch sensitivity. ARP2000 is tempered above that temperature range and has a strength between 200,000 and 220,000 psi.

Translation: No matter what you do to stainless, you can't get its tensile strength to come close to matching a martensitic alloy steel.

Aerospace Specification Metals Inc - AISI Type 304 Stainless Steel

Yield Strength - 31.2ksi
Rockwell Hardness (B-scale): 70

Even the cheap and plentiful A36 low alloy steel has a Yield Strength of 36.3ksi, and is identical in hardness to 304 on the Rockwell B-scale.

AircraftMetals.com - C300 Maraging Steel

Yield Strength (annealed, aka "dead soft") - 120ksi (4X greater yield strength than 304 stainless)
Rockwell Hardness (C-scale): 30
Yield Strength (aged at 900°F for 3 hours) - 280ksi (9X greater yield strength than 304 stainless)
Rockwell Hardness (C-scale): 52

Rockwell B-scale hardness of 87 = Rockwell C-scale hardness of 1

Substitute aircraft landing gear steel for stainless steel, and then you don't need an isogrid or orthogrid. A "nosogrid" pattern is A-OK.

A nosogrid pattern is also known as plain old sheet or plate steel.

What's so great about this "nosogrid" pattern I speak of?

For starters, it requires zero machining. It requires no special tools or techniques to repair, either. You cut out the affected area, weld in another piece of sheet or plate, and then you're done. It can either be the same weight as 304 for 4X to 9X greater strength, or it can be much thinner and therefore lighter for equivalent strength. C300's strength-to-weight ratio is about 1/3rd greater than the hardest Titanium alloys, which are also far more brittle than any of the steels being discussed here.

C300 may require some corrosion protection, but that is absurdly easy to do. Spray a ceramic oxide coating onto the steel. Bake the coating on. Problem solved. If baking is problematic because it requires an oven, then plasma spray the coating onto the steel. Again, problem solved. It will then withstand corrosive environments that would badly corrode 304 or even 316 inside of a month.

C300 can be had in powdered form for Hot-Isostatic Pressing as well. It forges well. It welds well. It can be hot or cold worked. It resists crack propagation quite well (which is why it gets used in landing gear). It also happens to have a chemical composition that matches up quite nicely with asteroid metal content.

If C300 is too expensive, then HY100 is an even more inexpensive low alloy steel that is both a certified aerospace material and is actually used in naval construction to build high strength pressure vessels like nuclear submarines.

Laser Beam Welding of HY80 and HY100 Steels Using Hot Welding Wire Addition

You can laser beam weld HY100 inside or outside of an atmosphere with appropriate shielding gas.

HY100 also has more than 3X greater yield strength than 304 stainless. If you're going to spend the money on 304, then at least use 4130, a little over 2X the yield strength of 304 and 90+ on the Rockwell C scale. It's as hard as a crankshaft or a gun barrel, because this is what they're made from. Basically, it's a moderately hard tool steel and is as tough as tool steel. If you had a battle axe, you couldn't hurt the hull if it was made from HY100, much less C300 or 4130. You don't have to worry about walking on any of those steels, or dropping something on it, because it's going to be A-OK afterwards.

As far as cost is concerned:

A36 Mild Steel: $300/t to $600/t
HY100: $500/t
Maraging C300: $600/t to $750/t
304 Stainless: $1,800 to $2,300/t
SAE 4130: $800 to $2,000/t
Inconel 625: $40,000/t to $50,000/t (seamless tubing prices, no idea about the base metal, but scrap price is $18,000/t)

Now everybody knows why a car chassis is typically made from A36, right?

Not even Rolls Royce uses special steel. Their car chassis steels are 1.5X as thick as most others. That's why they're stronger, but don't cost any more than a car chassis made from a specialty steel. They spend plenty of money on the car to make it one of the nicest in the entire world, just not on steel. Put another way, you can affodably source enough material for 3 complete ship hulls using anything but 304 or 4130. If we're talking about A36 mild steel, almost the same mechanical properties as 304 except for corrosion resistance, then 5 complete ship hulls. If you want corrosion resistance, you coat the steel with a ceramic oxide. That makes it more corrosion resistant, at normal or elevated temperatures than any type of otherwise unprotected steel will ever be.

If you're dead set on using 304, then you can increase the yield strength to the point that it doesn't require an isogrid pattern using an extremely powerful forging machine that can drastically reduce the cross-section of the metal plate during the forging operation, bumping tensile strength up to 170ksi or so. However, HY100 and C300 do not require those massive forging dies to confer the tensile strength that the sheet or plate has by virtue of its differing crystalline structure.

If a 2mm thick 304 stainless was sufficient to withstand 14.7psi, then a 0.22mm thick C300 would have equivalent strength. 0.22mm is about as thick as two sheets of copier paper stacked on top of each other. If a C300 hull was a whopping 0.5mm thick, then it has more than double the tensile strength of a 2mm thick 304 stainless. If we need more stiffness, which is required for the 304 because it's so soft and weak by way of comparison, then we can easily weld sheet metal ribbing onto the hull. If we elect to devote 1,000t of steel to the ship's hull no matter the design used, then our ship is minimally 9X stronger, the metal is always 2X to 3X harder, and the pressurized structures can be much stiffer as a result, therefore less likely to fatigue into uselessness over time.

SpaceNut · 2022-03-26 12:31:05

Th. for what will be used we can not even tell what mass let alone how much it will cost until its fully discussed and its not just for the hull its the total ship.

edit
post 7 is for when you are writing a contract to get a supplier to provide the materials for the build and not the engineering that is required.

my post 12 continuation for what metals and of what thickness.

SpaceX switched away from carbon fiber is cost, as stainless steel costs $2,500 per ton versus $130,000 per ton for carbon fiber.

The Starhopper, he explained, used 12.5 millimeter thick steel. The SN1 prototype uses four millimeter thick steel. For optimized versions, they could go as low as two millimeters in areas with a circular steel design that measures 9,000 millimeters in diameter.

https://www.teslarati.com/spacex-sleeve … rage-tank/

https://www.reddit.com/r/SpaceXLounge/c … starships/

Falcon 9 wall thickness: 4.7 mm
Shuttle external fuel tank wall thickness: 2.5 mm
Apollo lunar module wall thickness: 0.305 mm

https://space.stackexchange.com/questio … cket-tanks

Shuttle External Tank was as thin as 2.5mm.
Atlas -- 0.1 to 0.4 inches (2.5 to 10 mm) thick
Centaur upper stage tanks -- 0.014"--0.016" (0.36 to 0.41 mm) thick
Saturn V's 1st stage tanks varied in thickness from 0.170"-0.254" (4.32 to 6.45 mm)
Falcon 9 apparently has 3/16''-thick walls (4.7mm).
ariane 5 the thickness is: 8mm for the solid boosters 4mm for the cryogenic main stage.

tahanson43206 · 2022-03-26 13:51:14

For SpaceNut .... Post #20 appears (as I read it) to cast doubt on the viability of the project.

If this project succeeds, it will because everyone involved commits to solving whatever problems are found along the way, and not giving up just because we are facing what appear to be obstacles.

The Large Ship most certainly CAN be built. There is nothing about the scale of the project, or any of the technologies involved, that have not been done before.

GW Johnson has shown a way the flight can be accomplished with chemical propellant, and since there is nothing new required in technology, I recommend we simply buckle down and do what is necessary to move the project along.

Lamenting a particular obstacle, and offering to give up, is NOT the way forward.

The immediate concern, and the BOM item I am focused upon as we head into the next Zoom meeting, is the specific shape, configuration and material makeup of the pressure hull plates.

In the next Zoom meeting, I am hoping for progress in defining the girder structure to which the hull plates are to be welded. I believe (subject to correction of course) that the structures are called "formers" and "stringers".

As a near term outcome of deliberations, I would like to see firmed up Blender drawings of the entire ring girder assembly, including segment specifications that will fit in a Starship freight carrier.

(th)

kbd512 · 2022-03-26 13:59:42

I don't see anything that looks like an insurmountable obstacle here. Some practical compromises need to be made, but we have the tools and materials to construct colonization ships. I don't see chemical propulsion as a practical option. We have electric propulsion that can provide the thrust required, even if it takes more time. Fuel economy in orbit is king, or else you're burning so much gas that the gas bill becomes the limiting factor that slows down colonization.

So what if we need giant solar arrays?

That's never stopped us from building them on Earth and the ISS solar arrays were nowhere near as big as they could be made. Given appropriate radiation protection, smooth and gradual acceleration / deceleration is good for the ship and good for the crew. We have sunlight 24/7/365 in space, so we may as well use it. That's the major advantage to being in space- more energy from the nearest fusion reactor than you can shake a stick at, at all times. If you can do some kind of nuclear fusion propulsion, then that's added gravy.

RobertDyck · 2022-03-26 15:25:45

Young Sheldon advertised for old smoke detectors to be sent to him. He extracted the nuclear material. Intended to build a nuclear reactor to supply power to his block. Somehow the powers that be didn't like a 10-year-old boy building a nuclear reactor in his parents' garage.
Bildschirmfoto%2B2019-01-24%2Bum%2B22.21.42.png

::Edit:: I'll do some math because I can't resist. Each smoke detector has on average 0.29 micrograms of Americium-241. I thought that isotope was not fissile, but according to Wikipedia it is, critical mass of a bare sphere is 55–77 kg. There's a 1,000 micrograms per gram, and 1,000 grams per kilogram. So assuming the lower end of that estimate, minimum mass for a bare sphere to start to react is 55kg. So young Sheldon would have to extract nuclear material from 189,655,172 smoke detectors. That could be reduces somewhat by a neutron reflector, assuming the 10-year-old knew that. Say reduce critical mass in half, as a rough rule of thumb. The image of the workbench appears to have a dozen smoke detectors open, and a stack not yet opened. As I recall from the episode, he had a couple cardboard boxes with more. So a few dozen. He required over 90 million smoke detectors. These are old smoke detectors, so the nuclear material would have gone through radioactive decay. That isotope has a half-life of 432.2 years, after 20 years 96.843% will remain. So he would need about 100 million smoke detectors. I think he had a way to go. Not really a hazard for the neighbourhood.

Last edited by RobertDyck (2022-03-26 19:33:28)

SpaceNut · 2022-03-26 16:08:51

71c5cf33-21e3-494d-9a04-8a14e15eff74-e8haippviauzag7.jpeg?w=710&h=947&fit=max&auto=format%2Ccompress

Without this modified for our intent we can not build what we desire.

It requires even more than that to support the build of even just the Hull casing as we need to plan out all features to it internal and external and what that requires as well.

kbd512 · 2022-03-26 19:07:50

Robert,

At least he wasn't trying to get our whole big universe in a hot dense state, just enough heavy metal to go critical.

New Mars Forums

Announcement

#1 2022-03-21 07:44:43

Large Ship (Prime) Bill of Material / Mass Allocation

#2 2022-03-21 07:56:30

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#3 2022-03-22 19:13:29

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#4 2022-03-22 19:26:27

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#5 2022-03-22 19:51:44

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#6 2022-03-22 21:08:06

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#7 2022-03-22 21:49:12

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#8 2022-03-22 23:45:42

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#9 2022-03-23 06:19:09

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#10 2022-03-23 06:29:36

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#11 2022-03-23 12:29:52

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#12 2022-03-23 18:56:31

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#13 2022-03-24 08:49:50

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#14 2022-03-24 09:10:00

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#15 2022-03-24 09:39:43

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#16 2022-03-24 09:46:44

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#17 2022-03-24 20:26:29

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#18 2022-03-25 05:26:49

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#19 2022-03-25 12:11:59

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#20 2022-03-26 12:31:05

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#21 2022-03-26 13:51:14

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#22 2022-03-26 13:59:42

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#23 2022-03-26 15:25:45

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#24 2022-03-26 16:08:51

Re: Large Ship (Prime) Bill of Material / Mass Allocation

#25 2022-03-26 19:07:50

Re: Large Ship (Prime) Bill of Material / Mass Allocation

Board footer