[HN Gopher] The guidance system and computer of the Minuteman II...
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The guidance system and computer of the Minuteman III nuclear
missile
Author : magnat
Score : 88 points
Date : 2024-08-19 19:06 UTC (3 hours ago)
(HTM) web link (www.righto.com)
(TXT) w3m dump (www.righto.com)
| kens wrote:
| Author here if anyone has questions...
| OldSchool wrote:
| Excellent presentation, thank you!
|
| The machinery is ironically beautiful to look at!
|
| How did this compare to its approximate contemporary in the
| USSR ?
| metadat wrote:
| What is the purpose of the window?
|
| (As labeled in https://static.righto.com/images/minuteman-
| mmiii/guidance-la...)
| QuinnyPig wrote:
| From the article:
|
| > Also note the window in the side of the missile to allow
| the light beam from the autocollimator to reflect off the
| guidance platform for alignment.
| metadat wrote:
| Thanks, I finished reading the article while in the air and
| realized my faux pas without any Internet! Cheers.
|
| It's labeled in another image towards the end:
|
| https://static.righto.com/images/minuteman-mmiii/silo.jpg
| ulnarkressty wrote:
| The article states that the system was cooled using a solution
| of sodium chromate to inhibit corrosion. However the wiki page
| of sodium chromate states that it is very corrosive. Is it a
| typo or something?
|
| It's also mentioned that the computer uses one of the first
| integrated circuits for miniaturization. Do you know if this
| can be definitely traced to advances in industrial/consumer
| products? It's a common trope that military research trickles
| down - so it's a "good" thing. It's not clear if this actually
| happens or if progress would have been made eventually without
| the need for these machines.
| philipkglass wrote:
| _The article states that the system was cooled using a
| solution of sodium chromate to inhibit corrosion. However the
| wiki page of sodium chromate states that it is very
| corrosive. Is it a typo or something?_
|
| Chromates are effective corrosion inhibitors for aluminum
| alloys and some other metals. Here's a brief article about
| how they work with aluminum:
|
| "Inhibition of Aluminum Alloy Corrosion by Chromates"
|
| https://www.electrochem.org/dl/interface/wtr/wtr01/IF12-01-P.
| ..
|
| When the Wikipedia entry's "Safety" section says that sodium
| chromate is corrosive, in context it means "destructive to
| human tissue by contact." That is, like sodium hydroxide
| (lye) and many other chemicals, in concentrated form it can
| destroy skin and eyes.
| kens wrote:
| Sodium chromate is highly corrosive to humans (as well as
| carcinogenic, see the movie Erin Brockovich). However, it
| inhibits corrosion in metal, acting as a passivating
| inhibitor, forming some sort of protective oxide.
|
| I've been doing a lot of research on the impact of Minuteman
| and Apollo on the IC industry (which led to the current
| post). The Air Force likes to take credit for the IC
| industry, as does NASA, but the actual influence is
| debatable. My take is that both projects had a large impact
| on the IC industry, more from Minuteman. However, even in the
| absence of both projects, there was a lot of interest and
| demand for ICs. If I had to take a quantitative guess, I'd
| say that those projects advanced ICs by maybe a year, but the
| basic trajectory would have remained the same.
| izacus wrote:
| How does a 1-bit serial computer actually work? E.g. how does
| an ADD operation look like? It's a bit hard to picture.
| kens wrote:
| In a serial computer, you have a 1-bit ALU, say an full adder
| that generate a sum and carry. Each clock cycle you read two
| bits and feed them into the adder, and then you write back
| the sum. You hold the carry in a flip-flop to use in the next
| clock cycle. It's just like doing a binary addition with
| pencil and paper, one bit at a time.
|
| Note that you need to start with the lowest bit with a serial
| computer, which explains why x86 is little-endian. It goes
| back to the Datapoint 2200, a desktop computer made from TTL
| chips and running serially. The Intel 8008 processor was a
| copy of the Datapoint 2200 (as was the Texas Instruments TMX
| 1795). Although the 8008 was parallel, it copied the little-
| endian architecture of the Datapoint 2200.
| bloopernova wrote:
| Do you have any plans to write about World War 2 era mechanical
| firing computers? I searched your blog but didn't see anything.
|
| Or maybe early RADAR systems of 1942 and later?
|
| (been reading about WW2 Pacific naval/air wars, and I am
| curious about these new-at-the-time technologies)
| kens wrote:
| I planned to write about the electromechanical Torpedo Data
| Computer used in WWII, but I got distracted.
| bun_terminator wrote:
| I have a morbid curiosity to know how much of all that old tech
| would actually work in a full scale nuclear war, launching all
| missiles. Seems so well thought-out, but also incredibly hard to
| test. Really fascinating article!
| akira2501 wrote:
| Why would it be hard to test? We have our own anti-missile
| technology, so it's ostensibly as simple as not putting a
| payload on the missile, then launching it at your own test
| range.
| dumah wrote:
| The physical environment these weapons were designed for is
| extreme and only possible to simulate piecemeal.
|
| Each stage needs to function in the presence of nearby
| nuclear detonations, resulting from both adversary and
| friendly weapons.
|
| These detonations are expected to cause severe shock,
| thermal, radiation, and electromagnetic transients.
|
| In the case of the most important targets, it is guaranteed
| that numerous detonations near the target, from ABM systems
| and friendly impacts, will occur, and these systems have been
| engineered and are expected to perform reliably under such
| conditions.
| akira2501 wrote:
| This weapon is an ICBM. The payloads are delivered to orbit
| then launched at the target from there. You're already
| facing severe shock, thermal, radiation and EM transients
| just to get to orbit. Once there, you're ultimately
| dropping MIRVs, the design of which is considerably
| simpler.
|
| The delivery vehicle and the reentry/payload vehicle have
| entirely different life cycles and deployment concerns.
| kens wrote:
| They did dozens of tests of the Minuteman missiles and reentry
| vehicles. The warheads were tested underground until the
| comprehensive test ban treaty of 1996. So it's pretty likely
| that the systems would work if needed. One risk is that
| something may have gone wrong with the warheads over 30 years.
| (Of course they maintain them, but without testing you can't be
| sure.) Another risk is that you don't know how the missiles
| would function in an environment with nuclear blasts and EMP
| all over the place. They put a whole lot of effort into
| mitigating these factors, but you can't be sure. Hopefully we
| never find out.
| leeter wrote:
| Note: While none of the Annex 2 countries that are
| signatories have conducted tests since 1996; the treaty never
| took effect because it was never ratified by all the required
| countries. Most notably the US, China, and Russia (although
| all three signed). In 2023 Russia officially withdrew,
| allegedly based on the US non-ratification. At least one
| political candidate for the presidency in the US has
| advocated for resuming testing. It is not inconceivable that
| testing could resume in the near future.
|
| Opinion: I don't think the US would if Russia or China didn't
| first. China likely won't for the same reason the US doesn't
| need to: they have super-computers and the sims line up with
| the data from prior tests. Russia might however if only to
| saber rattle, although they likely don't need to either.
| Russia however is likely not in any hurry to have a test
| failure right now. So while testing could resume, I wouldn't
| put money on it.
| Joel_Mckay wrote:
| There was an area of redundant symmetric electronic design,
| that auto compensated for component level failures. I remember
| reading an "aerospace" manual all about it when I was a kid. It
| was necessitated when the tolerance and reliability of
| components were terrible by today standards.
|
| Note too, that mil spec silicon is different in that it is
| resistant to CMOS latch-up, redundant CRC protected self-
| correcting consensus register ops, and large gate sizes less
| sensitive to Gamma radiation.
|
| It was an interesting time, and a few people still think living
| under the Sword of Damocles builds character. =3
| detourdog wrote:
| Here is a link to a bunch of artifacts from of those
| computers and their development.
|
| https://www.icloud.com/sharedalbum/#B0YG4TcsmGWIVSf
| kens wrote:
| Nice collection of Autonetics photos! Are those your
| photos?
| detourdog wrote:
| Yes, I'm the guy the always promises to mail you the
| chips but always fails at the follow through.
|
| Seeing this article make me Think I really have to get
| you these chips.
| kens wrote:
| I'm always ready with my microscope to take some die
| photos!
| Joel_Mckay wrote:
| There are several chip lines that used this method over
| the years for various reasons:
|
| https://en.wikipedia.org/wiki/Wafer_backgrinding
|
| Best regards =3
| Ringz wrote:
| Impressive work and very interesting! Since I was instantly
| interested in the tiny ,,window" and its purpose I found a little
| error:
|
| ,,Aligning the missile was a tedious process that used the North
| Star*t* to determine North.,,
| kens wrote:
| Thanks! I fixed that.
| firesteelrain wrote:
| Your article on the guidance system reminds me of this
| https://youtu.be/bZe5J8SVCYQ?si=LuVwiZ7NEI21czoH
| kens wrote:
| I refrained from including that link :-)
| minkles wrote:
| Ha that's great. I was expecting this for some reason
| https://www.youtube.com/watch?v=yXFh54fc8GM
| benjam47 wrote:
| I live several miles from a Minuteman silo in Montana, maintained
| by Malmstrom Air Force Base. The underground cabling between
| sites is also an interesting read
| (https://minutemanmissile.com/hics.html). Anytime I want to dig
| on my property, I have to make sure it won't interfere with their
| pressurized cables. I have heard a story from someone that did
| accidentally cut a cable, and Malmstrom AFB was able to locate
| the break and respond rapidly. I am a volunteer firefighter, and
| our station has a VHS tape and a paper guide titled "Incident
| Guide for Missile Field Fire Response" provided to us by the DoD
| regarding our role in responding to fire incidents near or at a
| silo. A year or so ago, we did respond to a fire near a silo, but
| it occurred entirely outside the security fencing. My
| understanding is that the personnel at the silos also have their
| own ability to respond to fires.
| minkles wrote:
| Just a bit of additional trivia. Jim Williams (somewhat famous EE
| at Linear) had a minuteman computer on his living room wall known
| as "the tapestry": https://www.eetimes.com/photo-gallery-
| remembering-jim-willia... (last picture in particle). Not sure
| what revision.
| kens wrote:
| Those boards are from the Minuteman I, the cylindrical
| computer. I wonder what happened to his boards?
| minkles wrote:
| Thanks for confirming (and thanks for the excellent article
| btw). I wish I knew for sure. Anything of that nature
| deserves to be carefully preserved.
| blantonl wrote:
| These systems are so vastly complicated, old, and rarely if ever
| launched. These aren't like data center generators which have
| testing schedules etc, and STILL there are failure points.
|
| I really wonder what the failure rate would be if they were all
| actually launched today. And I mean failure, from not lifting
| off, to failure in flight, to misguided warheads etc.
| minkles wrote:
| They have operational models with statistical failures included
| so they understand what the interception and failure
| probabilities likely are for each item at component level. You
| can design that into a system and test for it.
|
| Obviously you can't factor in unknown problems but that's what
| drills and test flights are for.
| jonathanyc wrote:
| > The new guidance platform also added a gyrocompass under the
| alignment block, a special compass that could precisely align
| itself to North by precessing against the Earth's rotation. At
| first, the gyrocompass was used as a backup check against the
| autocollimator, but eventually the gyrocompass became the primary
| alignment. For calibration, the alignment block also includes
| electrolytic bubble levels to position the stable platform in
| known orientations with respect to local gravity.
|
| Had never heard of gyrocompasses before. I worked on a small
| robot in the past and remember having to calibrate the magnetic
| compass, which was not very accurate (similar to smartphone
| compasses). I never thought about how they'd get super precise
| headings for ICBMs.
|
| The Encyclopedia Britannica article on gyrocompasses is really
| good. Here it explains why you can't use a gyrocompass on a
| vehicle on fast aircraft (and I guess small robots that are
| jostled around a lot):
|
| > A major contribution by Schuler was the discovery that, when
| the period of oscillation is 2p[?](Earth radius/gravity), the
| heading precession of the gyroscope spin-axis due to acceleration
| is exactly the rate of change of the angle between the apparent
| and true meridians seen on a moving vehicle. The gyrocompass will
| then read true north at all times if its indicating reference is
| offset by the angle between these two meridians. The angle, at
| ship speeds, is a direct function of the north-south speed and is
| easily set into the system. The need for accurate speed
| measurement for this offset is the main reason why a gyrocompass
| is not practical for use in aircraft.
|
| https://www.britannica.com/technology/gyrocompass
|
| Love this article!
| maxglute wrote:
| What's the actual color of the yellow paint? Goldish like first
| pic of lemonish like latter pics. Contrast/aesthetics of the gold
| is just chefs kiss. There's something about American MIC pallette
| that rarely miss.
| tempaway4575144 wrote:
| _The idea behind inertial navigation is to keep track of the
| missile 's position by constantly measuring its acceleration. By
| integrating the acceleration, you get the velocity. And by
| integrating the velocity, you get the position._
|
| This sounds like it couldn't possibly work (surely all the little
| errors compound?) but apparently it's how Apollo navigated
|
| https://wehackthemoon.com/tech/inertial-measurement-unit-mec...
| Zircom wrote:
| I mean it's a nuclear missile, millimeter accuracy isn't really
| necessary. Somewhere in the general vicinity is good enough for
| it's purpose of going boom.
| spoonfeeder006 wrote:
| Interesting tech and all, but ultimately efforts like this are a
| waste. If we humans could instead get over our self-perceived
| need to engage in warfare for childish reasons then we could
| dedicate such efforts to more productive things like helping
| homeless people get housing and skills, or developing better
| psychological sciences to help drug addicts get free from their
| disease of addiction, you name it
|
| > O SON OF SPIRIT! The best beloved of all things in My sight is
| Justice; turn not away therefrom if thou desirest Me, and neglect
| it not that I may confide in thee. By its aid thou shalt see with
| thine own eyes and not through the eyes of others, and shalt know
| of thine own knowledge and not through the knowledge of thy
| neighbor. Ponder this in thy heart; how it behooveth thee to be.
| Verily justice is My gift to thee and the sign of My loving-
| kindness. Set it then before thine eyes. > > ~ Baha'i Teaching
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