Redux of ISS If we could

SpaceNut · 2019-07-05 16:24:58

Here is what started off the topic in.

Its sad that Nasa has taken so long to get this going NASA seeks proposals for commercial ISS modules

RobertDyck wrote:

We have used aluminum alloy with an isogrid to reduce weight. How much would it weigh to use stainless steel sheet metal with something similar to an isogrid? Perhaps GW Johnson can tell us how long such a module would last, how to fabricate such a thing, and how much weight gain vs current module design.

If I was making a new module with stainless versus Aluminum alloy the one feature to make it easier to construct is to not change the material thickness unless its inferior to the pressures of use.
Isogrid is a pattern to use less materials but to still give it strength.

https://www.wenzelmetalspinning.com/ste … minum.html

https://eagle-aluminum.com/blog/steel-vs-aluminum/

https://tampasteel.com/5-differences-be … -aluminum/

https://www.metalsupermarkets.com/10-di … ess-steel/

RobertDyck · 2019-07-05 16:47:17

The reason I ask about changing to stainless is durability. Once a module is in space, it needs to stay there for decades. Pressure shouldn't change much, pressure is stable. Temperature changes, but there are thermal blankets to mediate extreme temperature fluctuations. The airlock experiences pressure cycles, but other modules remain pressurized. The first module for ISS was launched in 1998. It's 21 years old now; modules obviously have to last longer than that. So what material do we need to ensure modules can last 100 years? I'm serious, equipment can be updated/replaced but we are learning the pressure hull must last a very long time. Soviets replaced space stations often: Salyut 1 through 7, and Mir. The intended to replace it with Mir 2, but after the Soviet Union broke up they didn't have the money. Components for Mir 2 are now part of ISS, including the first 2 modules: Zarya and Zvezda. Neither Russia nor NASA have funds to replace ISS with another station. The Douglas DC-3 was produced 1936-1942 and 1950; there are still commercial aircraft in operation today. They aren't in the air 24/7, but still! This demonstrates the need for a reliable facility; 1936 to today is 83 years, ISS must last at least that long. Zvezda docked with Zarya in year 2000, so replacement modules must last at least 64 years from launch.

Stainless steel is stronger than aluminum alloy, so it may be possible to mitigate mass gain by reducing thickness. Aluminum hulls are already thin, not sure how much can be gained that way. And manufacturing with stainless is different than aluminum. I'm hoping GW Johnson will chime in.

SpaceNut · 2019-07-05 19:04:13

It seems that Nasa is finally ready to make the station into a commercial use in the future.

What a Space Vacation Deal

Starting in 2020, the station will be open to vacationers and others at a per-night-rate of $35,000.

While this is the first time the American side of the ISS has been promoted as a high-flying hotel, there have been five tourists who have visited the Russian side of the station, starting with Dennis Tito in 2001. He spent eight days in the ISS.
The hotel room was part of a complete travel package negotiated with the Russians. The total cost was $20,000,000 including round-trip accommodations on a Soyuz spacecraft. Dennis probably thought this was an expensive trip, but he could afford it.
As it turns out, he had a great deal on the hotel accommodations and the transportation. Today, Dennis would have to pay $245,000 per week for an "American room" and probably close to $60,000,000 for the round-trip transport to and from the station.

So how is Nasa going to generate 3.5 billion for a yearly funding for its end of the bargain.

GW Johnson · 2019-07-06 10:06:15

Structures made from aluminum are lighter than structures made from any steel, including stainless, because the tensile strength/density ("strength to weight") is better with aluminum. If heat is involved, the steels are the better choice, still possessing considerable strength at 700-1000 F when aluminum is a fluid puddle at 1000 F. Aluminum strength is pretty much gone at 300-400 F.

The "strength" in "strength to weight" is usually something like an ultimate tensile strength or a yield strength. This is the wrong value to consider, unless you are doing a one-shot non-reusable design. All metals suffer fatigue damage, but aluminum is infamous for it. This was a bit of a mystery until investigated thoroughly, and found to be the cause of the fatal DeHavilland "Comet" crashes of the early-to-mid 1950's.

Mind you there is a different plot for every type of loading, but the usual form is a log-log plot of cyclic stress level versus number of cycles to specimen failure. The usual layout is stress on the vertical axis, and cycles on the horizontal axis. In log-log format, data correlate as a straight line fit, with a negative slope, except that at low enough stress, the slope zeroes out level and flat. What that says is that for a low-enough loading level, fatigue life is infinite.

Otherwise it is predictably finite. The higher you stress the part, the shorter its life. Up near yield or beyond, a single handful of cycles is the most you could ever expect.

When Donald Douglas designed the DC-2 and DC-3, he used a cellular structure of ribs and multiple spar-like members, such that any one part was very lightly loaded. He did not understand fatigue life then, he was just lucky. Those stresses just happened to fall on the infinite fatigue life portion of aluminum's behavior, as determined by other investigators around 2 decades later.

THAT low-stress design approach is the only reason why DC-3's still fly today 70 and 80 years (and millions of flight hours) after their manufacture. Many were downed by hostile fire, weather, engine failure, or crew incapacitation, but none ever broke up structurally in midair from fatigue. You get what you pay for: the DC-3 has a higher inert mass fraction than modern transports, and so carries less payload for less range, even adjusting for the lower flight speed.

The more modern prop and jet aluminum transports were usually designed for something like 40,000 cycles. They get sold off to the 3rd world when over-aged, who then suffer the mid-air breakups. (How do you like those corporate ethics? But that's a different story.)

The B-52 suffers from fatigue problems. It is still flying, but has had its wings and tails replaced more than once. Only the H-models still fly (A-G were junked years ago). The last one of those rolled off the production line in May 1961. There was one B-52A flying at Edwards AFB for NASA. It carried the X-15, but has been junked. The first B-52's came off the assembly line in 1952.

If you stay under the infinite fatigue stress limit for aluminum and for stainless steel, the allowable stresses for aluminum are quite low, somewhere around 5 ksi. Stainless's fatigue limit is much higher, nearer 20 ksi. (Values vary greatly with alloy and with type of loading.) Most of the strength/weight advantage of aluminum pretty much disappears under those circumstances. If you fly faster than about Mach 2.2, you start replacing hot parts with stainless steel and titanium. By Mach 3, pretty much the whole airplane is stainless steel or titanium. Stainless will go hotter than titanium will go.

"They say" that composites have an infinite fatigue life. I do not believe it!

After some lifetime, weathering and internal delamination cause failure. I've already seen it. It has already caused some fatal crashes, just not an airliner yet. Fatigue life (or whatever you want to call it) of a composite is finite, it is just not yet understood properly. Same as was fatigue of metals behavior in 1950 just before the "Comets" crashed.

Re: "Comet" fatigue failures. Pressurized cabins were a new thing in 1950. Failure occurred at the corners of the windows, where stresses were greatly magnified by the sharp corner. The crack propagating from the first window corner to crack would cause the fuselage to split wide apart in cruising flight at high altitude (really disappointing for the occupants).

This is why modern jet airliner windows have rounded (and thicker-framed) corners today: to lower the corner stresses, and thus increase fatigue life of those parts back up to where the rest of the fuselage parts run.

GW

Last edited by GW Johnson (2019-07-06 10:25:09)

RobertDyck · 2019-07-06 12:04:09

How very vague. That's the same stuff you posted before. Specifics. What does it take to ensure station modules will last the life I just said.

SpaceNut · 2019-07-06 12:36:49

Aluminum has a tensile strength of 276 MPa and a density of 2.81gcm-3. ... Stainless steel has a tensile strength of 505 MPa and a density of 8 gcm-3. Stainless steel is, therefore, stronger than aluminum.

https://www.shieldcoart.com/custom-meta … metal-sign

So the chamber for exit from a module will need to be full thinkness where as it looks like the remaining module portion can be reduced as it does not change.

GW Johnson · 2019-07-06 15:03:35

I've had lots of complaints, but specifics was never one before!! (Ha ha ha !!!)

Unless heat above 300 F is involved, you can make very long-life modules out of aluminum. For whatever the loading is, use the fatigue curve for that loading and alloy, and stay out on the flat for allowable stress less than the infinite fatigue life limit, by around a factor of 2. The module will still be lighter than a thinner one made of stainless, but only slightly.

The allowable tensile stress will be a lot closer to 3-5 ksi than the 40 ksi = 276 MPa that Spacenut quoted, almost no matter which alloy or what loading. Allowable shear stresses will be around 2/3 that value. Allowable bearing stresses might be twice that value. Bending stresses are related to tensile, usually, but also depend upon lateral collapse stability and effective bracing. These values are very variable, and depend upon the nature of the loading, including whether it reverses or not in its cycling.

You have to count up how many day/night heating/cooling cycles there are, and how many airlock pressurization cycles there are going to be. You also have to look at the expected number of docking force applications you have to survive as spacecraft visit. It's a bit complicated, but if you accept the low allowable stresses associated with infinite fatigue life, you really can have an infinite part life.

It just WILL NOT be aluminum foil-type thicknesses! It will have to be made of sheet more like what aircraft are fabricated from. Shell thicknesses nearer sheet thicknesses of .02 to maybe .06 inch (0.5 to 1.5 mm). Highly loaded parts like window and doorway rims will have to be plate, not sheet. That sort of thing.

GW

Last edited by GW Johnson (2019-07-06 15:09:31)

tahanson43206 · 2019-07-06 15:05:11

For GW Johnson re #479 ....

This is a request in support of RobertDyck in #480 .... It may be asking too much (of you or anyone else), but the question is certainly timely ...

What would it take to design a space structure to last 100 years. We humans are on the verge of needing that capability, if we aren't there already.

By coincidence, Gerard O'Neill's name came up in conversation where I am .... Dr. O'Neill is gone, of course, but his students are among those engaged in building out the infrastructure for space development. I understand that Elon Musk is NOT one of them, but Jeff Bezos appears to have been influenced by O'Neill's writings.
A quick Google search yielded this confirmation:

Why Jeff Bezos's Space Habitats Already Feel Stale - CityLab
https://www.citylab.com/perspective/201 … ../589294/
May 13, 2019 - O'Neill asked an advanced group of students to study a direct question: “Is the surface of a planet really the right place for an expanding technological civilization?” ... Jeff Bezos was one of Gerard O'Neill's students at Princeton in the mid-1980s.

O'Neill was thinking about structures that would last in space for extended periods, but my guess is he was anticipating an unlimited budget for those structures.

(th)

GW Johnson · 2019-07-06 15:13:16

I think I answered Tahanson43206's question in my post 482 above. Every detail part is different. The exception might be radiation damage to the material.

I dunno a whole lot about that, but at intense irradiation, the damage effect is real. You don't find aluminum used inside a reactor containment vessel. Part of that is heat, but part is radiation damage.

All materials suffer from it to one extent or another. It's why the reactor guys are so selective about the materials they use. Zubrin knows a lot more about that than I do.

About the only other thing to worry about is cold approaching the cryogenic. I know aluminum gets used for "one-shot" or "few-shot" propellant tanks, but the cryo storage tanks that have to last for years and tens of thousands of cycles here on Earth get made of 300-series stainless. That's just hard-knocks experience talking: it's simply the best there is for long life use with cryogenics.

GW

Last edited by GW Johnson (2019-07-06 15:18:08)

kbd512 · 2019-07-06 15:15:44

Robert,

How is that vague?

If you want a load bearing structure to last a really long time, then you design that structure in such a way that it's yield strength and plastic deformation limits are significantly above what the structure actually has to withstand in operational use. Typically, that means adding more mass. Stiffness, another important mechanical property, prevents a material from deforming under load and subsequently diminishing its ability to withstand a load applied to it. All well-understood structural materials have quantified mechanical properties at given temperatures and mechanical loadings, and strength varies considerably by temperature.

You seem to want some kind of engineering exercise to be performed, yet those exercises have already been completed by teams of hundreds of engineers who have determined what will work acceptably well. Simply stating that some structure must last for a century under a given set of operating temperatures and pressures and actually engineering it are two entirely different exercises. The fact that the ISS modules are still in one piece and not leaking like sieves after more than two decades in the shooting gallery of low Earth orbit is testament to the durability of those structures for that specific use case.

In crystalline structures such as metals, strength is lost whenever a single crack forms and begins to propagate. To signficantly enhance the strength of these structures, nano-sized ceramic particles that reinforce the grain boundaries of the crystalline lattice can be used. This type of reinforcement is colloquially known as a ceramic metal matrix composite. Alloying a base metal, such as Aluminum or Iron, with other metals is a much older technique, but the one most often used because it's so well understood. The newer technique has proven more effective than alloying, for a marginal increase in cost, but is still in its infancy. Beyond that, the purity of the materials used and the manufacturing techniques are quite important. It's not overly difficult to make a heavier part structurally weaker than a lighter part, so most of a part's design focuses on using materials that conform to a given set of specifications for materials with very well understood mechanical properties determined through exhaustive testing, part geometry that mass-efficiently resists deformation under load, and repeatable fabrication techniques to produce light but strong parts with good service life in a specific operational environment.

SpaceNut,

Stainless steel is only stronger than Aluminum by volume, not by weight. If weight is of no consequence, then you can always add more mass to something to make it stronger. For what should already be obvious reasons, this is problematic for all aerospace vehicles. Thus, the old adage, "Make the part as strong as it needs to be and no stronger." How strong the part "needs to be" is obviously dictated by the loads that will be applied to it. The use of "stronger-by-weight" structural materials such as Carbon Fiber or CNT, or composites containing those materials, is all about making something stronger for a given mass or weight.

Incidentally, GW is dead on correct about how modern aircraft are designed, whether we're talking about fighter jets or airliners. The engineers who design them are only interested in the machine surviving a pre-defined number of uses over a given period of time. This would be an example of a "duty cycle" or "fatigue life", before the part or structure is no longer capable of that type of use without an unacceptable risk of catastrophic failure. In order to make these aircraft lighter / stronger / faster, service life had to be sacrificed. The newer composites offer the promise of extended service life, but fabrication techniques have to be rigorously controlled and inspections using newer and more expensive techniques applied. In either case, to achieve service lives into perpetuity with aerospace vehicles, you will necessarily sacrifice fuel economy and useful payload. At some point, efficiency and useful load is more important than extreme longevity.

We know how to make a jet that can survive a 200mph impact with the ground, but it would fly like crap and even if the jet was in one pretty piece after it hit the ground at that speed, everyone inside it would still be killed by that sudden stop at the end of the flight. Basically, finesse at the controls and an operator who cares for his / her machine was deemed more useful than ultimate durability.

SpaceNut · 2019-07-06 15:25:36

Comparison values gave that....

Plus cnt flexing means a broken module...

Here is the radiation stuff which was posted already...

SpaceNut wrote:

Next to artificial gravity being absent its the lack of protection that is also troubling.
Radiation damage to the human body extends to the brain, heart and the central nervous system. Space radiation passes through matter and penetrates the human body. Energetic particles impact living tissues, impairing normal function of cells and even killing them. Scientists are encouraged to investigate radiation risks and how to stop them with the right countermeasures.
Space Weather causes years of radiation damage to satellites using electric propulsion
geostationary orbit can result in significant solar cell degradation
The study concludes that after a radiation storm, maximum solar cell output power could be reduced by up to 8% by the time satellites reach their target destination using electric orbit raising. This is equivalent to the level of damage that would be expected after spending around 15 years at geostationary orbit.
During a radiation storm, charged particles released by the Sun become trapped within Earth's magnetic field, forming the Van Allen radiation belts which encircle Earth, and collisions with these charged particles causes damage to the solar cells. This degradation is up to 8% of output power in a worst-case scenario, but even in a quiet environment, the study predicts a 1-3% reduction in output.
http://dx.doi.org/10.1029/2019SW002213

GW Johnson · 2019-07-06 15:26:46

As I said before, when you look at material strength to weight ratios, for something that only has to be used once, you can look at ultimate tensile strength divided by density. If it has to have a long life, you cannot use ultimate strength, but you still have to use the same density.

You have to use a stress at or below the fatigue limit, which for aluminum is factor 10 or more (!!!!) below ultimate. The steels do not suffer quite so large a reduction for infinite fatigue life, which offsets some of their higher density, in a strength to weight ratio.

As I also said above, it just so happens by fortuitous accident, the wings of the DC-3 (and DC-2) got designed well below what turned out to be the infinite-life stress for those alloys, in a non-reversed cyclic load test. That's why they have lasted 7 decades without cracking due to fatigue. Very few aircraft designs have ever fallen in that category. None since cruise speeds exceeded 300 mph.

GW

Last edited by GW Johnson (2019-07-06 15:28:11)

SpaceNut · 2019-07-06 15:42:59

Here is the thermal cycling values of rotation and of orbiting Space Station's Sun-facing side would soar to 250 degrees F (121 C), while thermometers on the dark side would plunge to minus 250 degrees F (-157 C).

https://hackaday.com/2018/03/12/lost-in … -in-space/

http://www.barringer1.com/mil_files/NASA-SP-8053.pdf

RobertDyck · 2019-07-06 18:01:42

kbd512: as long as modules have to be replaced, or operators of ISS seriously talk of decommissioning/de-orbiting it, then it hasn't been done acceptably well.

And I'm tired of people keeping me out of the loop. Members of the Mars Society are highly skilled. GW Johnson is a retired professional engineer. I'm a computer software developer, with experience developing software & firmware for real time embedded systems. We can do a lot. Together we (The Mars Society) form a team with rather high competency. So yes, I do want an engineering study. And NASA has been puttering about, wasting time and money, every time they are given a mandate by a President or Congress they squander the opportunity. So they need someone to kick them in the ass! The Mars Society is capable of doing that.

SpaceNut · 2019-07-06 18:16:17

Even of a higher severity is that mind of thought for the lunar gateway and transport system to mars. It needs to be made to last if its going to cost like it already has....or be built at such a low cost as to be able to throw it away.

tahanson43206 · 2019-07-06 18:34:46

for RobertDyck re #489 ....

Best wishes for success inspiring members of the forum to pitch in on a project ... The goal of designing a space habitat able to survive 100 years seems worth considering. I can speak only for myself (of course) but from GW Johnson I get the impression that if walls are to be made of metal, then stainless steel is superior to aluminum. Aluminum is abundant on the Moon, but iron and carbon would need to be procured from further out. A well chosen asteroid fragment might be just the ticket.

However, since no one else has brought it up, I'd like to invite consideration of the Bigelow module, which has been installed on the ISS for some time now, and which is reported to be holding up reasonably well as a storage locker. Can ** that ** technology last 100 years? We sure don't have an example to study.

In contrast, the lunar landing components which were discarded are accumulating useful data to study, if only there were a way to study them.

While searching for information about any lunar flight components which might still be in Solar orbit, i found the site at the link below, where observations of the Apollo spacecraft traveling to and from the Moon were recorded by Earth observers. There is a report of a Pan American aircraft turning to allow passengers to watch the passage of one of the return capsules through the atmosphere.

http://pages.astronomy.ua.edu/keel/space/apollo.html

To recap ... I'm wondering if the Bigelow space habitat offers potential to outlive metal structures.

The link below came up during a search for the Bigelow system. It is from June of 2017, and covers radiation experiments inside the module.

https://www.space.com/37068-beam-inflat … space.html

(th)

Last edited by tahanson43206 (2019-07-06 18:36:50)

SpaceNut · 2019-07-06 19:03:06

Bigelows inflatables require micro meteor shielding once we leave orbit and unless its design simular to the transhab concept they are just empty areas to grow into....

kbd512 · 2019-07-06 19:23:28

SpaceNut,

Composites don't fail in the same way that metals do. However, in my Starship Lite proposal, the part that the humans live in is mostly a multi-layer woven fabric. Bigelow's free flying module (not the one attached to ISS, the one that had to be proven to last for years before NASA would even agree to attaching one to ISS) has been floating around up there for many years now, still maintaining pressure. A woven CNT fiber shell would simply take achievable strength to the next level, grossly exceeding that of the various para-aramid fibers used in the Bigelow / TransHab inflatables, even with current manufacturing imperfections. In this application, it's well worth the additional cost.

Robert,

There are lots of systems inside the module that have been trashed over the years from decades of use. When it was designed, it was apparent that on-orbit replacement wasn't much of a consideration. So far as I know, nothing we can easily send into orbit can survive orbital velocity impacts into perpetuity. There's a design service life limit to nearly everything made these days, to include forged steel tools. Look at the bright side, though. Something designed in the 80's and built in the 90's is still chugging along in the 2020's. Our ability to make lighter and stronger aerospace vehicles has only increased over the decades.

Although I really wished we could, just because I want to see humans land on Mars before I croak, I don't think a bunch of amateurs are going to convince NASA to do much of anything. Anyway, nobody is trying to keep you in the dark. They hide all that knowledge of materials science and mechanical properties in these wonderful things called books. They don't even need to be plugged in at night, although reading in the dark is somewhat problematic and they really hate water. Since they're readily available online these days, they're arguably one of the worst kept secrets in aerospace engineering.

kbd512 · 2019-07-06 19:24:45

SpaceNut wrote:

Bigelows inflatables require micro meteor shielding once we leave orbit and unless its design simular to the transhab concept they are just empty areas to grow into....

You mean the inflatables need to be wrapped in the same fabric that the ISS modules are protected by, that the Bigelow module was already made from to begin with?

RobertDyck · 2019-07-06 20:25:24

kbd512 wrote:

They hide all that knowledge of materials science and mechanical properties in these wonderful things called books.

How very condescending. A lot of said material is available, but a lot is not. When I was a child, it was all hidden. I tried to get a hold of everything and anything, but all I got was silly sales brochures intended for "the general public". Now I can read reports from NASA's technical reports server. I've found reports that some NASA contractors I spoke with working on the station had never heard of. Certain "books" are kept hidden. Other knowledge is completely unavailable.

This reminds me of the time I dated a women who at the time was a contractor working for NASA in support of the station. She complained that she was trying to get the Russians to reveal how the "Elektron" works. That's the Russian oxygen generator. So I explained it. She was amazed that I could give her the answer "off the cuff". And she was the NASA representative for conference calls with Russia about the station. And you call us "amateurs".

This demonstrates the level of engineering detail I'm looking for. It also demonstrates both difficulty getting information, and that some information is more available than some people think.

Ps. After the Columbia disaster, that woman moved to work on returning Shuttle to flight. When that was done she moved to Lockheed-Martin. While there she called me one day, her boss was working on a commercial satellite project, she knew I had worked on a Mars Society project that included locating a supplier of commercial-off-the-shelf space hardened electronics. Lockheed-Martin needed that for their satellite, so they wanted contact information for my supplier. Again, I could answer "off the cuff". When Lockheed-Martin asks me for a referral, do you still call me an "amateur"?

SpaceNut · 2019-07-06 20:42:05

kbd512 wrote:

SpaceNut wrote:
Bigelows inflatables require micro meteor shielding once we leave orbit and unless its design simular to the transhab concept they are just empty areas to grow into....
You mean the inflatables need to be wrapped in the same fabric that the ISS modules are protected by, that the Bigelow module was already made from to begin with?

What I was trying to say and did so poorly at was the current micro meteor design is only good for LEO and that addition shielding will be needed for use beyond. Plus we are not using the ISS modules for the gateway only using them to aid in prototyping.

https://directory.eoportal.org/web/eopo … i/iss-beam

kbd512 · 2019-07-07 06:14:25

Robert,

From what you claim, I presume you're also capable of reading a book on Aluminum alloys or talking to a metallurgist. I usually just talk to metallurgists who specialize in whatever alloys I'm interested in. They can tell you what books and papers to read, as well as whatever they're working on. My particular application was a stud designed to expand at the same rate as the rest of the Aluminum block in an engine. A good FEA can predict what the results will be, with reasonably good accuracy, assuming very well characterized materials properties.

ISS modules were fabricated from truck loads of 2219. It's mechanical properties should make it a good match for the weight / strength / temperature requirements, even if the fabrication methods originally used were absurdly expensive. Apparently, aerospace structures engineers from NASA / ESA / ROSCOSMOS / JAXA all thought the same thing. Since none of the modules have suffered a mechanical failure after decades of use, there could be a bit of wisdom in there somewhere. Something like the CMC's I used might be even better, but extensive testing would be required before that could happen. The material is also more difficult to machine, decidedly more expensive than 2219, and slightly heavier. These are all things you learn after you actually try to do something, rather than just talk about it on the internet.

Regarding what we know or don't know, at least I can freely admit that I'm an amateur. All that time NASA is taking, that you think they shouldn't be taking, is squarely directed at proper design, engineering, and exhaustive testing. That pretty much tells me what I need to know about who the real amateur is here. The fact that you read something somewhere and think it makes you an instant expert on something is pretty telling, as is the constant need to have your ego stroked. If you want to prove to the rest of the world how intelligent and accomplished you are, then do it by actually designing something for the space program. All talk is quite cheap. Real engineering costs a fortune and rarely, if ever, takes as long as anyone thinks it should.

People have spent their entire careers developing individual alloys, but I get the sense that you seem to think someone is going to teach you this stuff in an internet forum posts. How close do we have to come to the pinnacle of self-deception to admit we have a problem?

Here's a crazy thought... Why don't you just contact Boeing?

They'd just love to hear how amateurish their efforts are from someone who's never designed or built anything that carries humans inside it. Just tell them you knew someone or read something off the internet. I'm sure they'll get a kick out of that.

SpaceNut,

A little light reading for your inner metallurgist:

NIST Materials Repository - Aluminum and Aluminum Alloys

NIST Materials Repository - METALLURGY OF HEAT TREATMENT AND GENERAL PRINCIPLES OF PRECIPITATION HARDENING

Protecting the Space Station from Meteoroids and Orbital Debris

SpaceNut · 2019-07-07 08:59:01

2219 is 93.0 Al, 6.3 Cu, 0.3 Mn, 0.06 Ti, 0.10 V, 0.18 Zn
Structural uses at high temperature (to 315 °C, or 600 °F). Highstrength
It is possible to cast or produce in sheet form and is malleable to hand tooling.
The Space Shuttle external tank (ET) alloy (Al 2195) for a large part of the tank structure but later switched to 2219 as well.

More than 100 different shields have been designed to protect the various critical components of the ISS, although all of the designs are modifications of three ISS primary shielding configurations: the Whipple bumper, the multishock (or stuffed Whipple) shield, and the mesh double-bumper shield.
The Whipple bumper, the simplest shield configuration, consists of a single plate of material (typically aluminum), called the bumper, spaced some distance from the underlying module wall (often called a catcher). The role of the bumper is to break up, melt, or vaporize a high-velocity object on impact. The smaller, slower remnants of the object then travel between the bumper and the catcher and spread the remaining energy of the impact over a larger area on the catcher.

Beam was set up as a test model for learning about how to best deal with radiation and to gain the impact data for perfecting the shielding.

RobertDyck · 2019-07-07 12:23:49

kbd512 wrote:

Here's a crazy thought... Why don't you just contact Boeing?

Actually, I did talk to several engineers who worked on Shuttle while it was flying. I had one particular idea to reduce labour required between flights, to reduce cost and launch more often. The first engineer I spoke to worked for Boeing, but this included engineers for Lockheed-Martin. Every single last one of them reported they had ideas to reduce labour and cost, every single last one of them said their supervisor told them to shut the fuck up! One said her supervisor told her that she's taking food from people's mouths. If you read Robert Zubrin's book "The Case for Mars", he has a similar story when he worked for Martin-Marietta, before they merged with Lockheed. But it's not just Dr Zubrin, while Shuttle was flying I spoke with several engineers working on it, they all reported the same thing. Management knows damn well they can reduce cost and reduce time, they don't want to. They're deliberately creating delays and cost overruns in order to increase profit in their pockets. And those former Shuttle managers are now working on SLS.

SpaceNut · 2019-07-07 14:19:15

Thats the government contract way....as it subsidizes the other parts of the business that is not doing as well...

The real question is how can we improve on the ISS design.

Its not just about the materials or science but how to make it go to where we want it to go as well.

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#1 2019-07-05 16:24:58

Redux of ISS If we could

#2 2019-07-05 16:47:17

Re: Redux of ISS If we could

#3 2019-07-05 19:04:13

Re: Redux of ISS If we could

#4 2019-07-06 10:06:15

Re: Redux of ISS If we could

#5 2019-07-06 12:04:09

Re: Redux of ISS If we could

#6 2019-07-06 12:36:49

Re: Redux of ISS If we could

#7 2019-07-06 15:03:35

Re: Redux of ISS If we could

#8 2019-07-06 15:05:11

Re: Redux of ISS If we could

#9 2019-07-06 15:13:16

Re: Redux of ISS If we could

#10 2019-07-06 15:15:44

Re: Redux of ISS If we could

#11 2019-07-06 15:25:36

Re: Redux of ISS If we could

#12 2019-07-06 15:26:46

Re: Redux of ISS If we could

#13 2019-07-06 15:42:59

Re: Redux of ISS If we could

#14 2019-07-06 18:01:42

Re: Redux of ISS If we could

#15 2019-07-06 18:16:17

Re: Redux of ISS If we could

#16 2019-07-06 18:34:46

Re: Redux of ISS If we could

#17 2019-07-06 19:03:06

Re: Redux of ISS If we could

#18 2019-07-06 19:23:28

Re: Redux of ISS If we could

#19 2019-07-06 19:24:45

Re: Redux of ISS If we could

#20 2019-07-06 20:25:24

Re: Redux of ISS If we could

#21 2019-07-06 20:42:05

Re: Redux of ISS If we could

#22 2019-07-07 06:14:25

Re: Redux of ISS If we could

#23 2019-07-07 08:59:01

Re: Redux of ISS If we could

#24 2019-07-07 12:23:49

Re: Redux of ISS If we could

#25 2019-07-07 14:19:15

Re: Redux of ISS If we could

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