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Inside a Titan missile guidance computer

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Re: Inside a Titan missile guidance computer

#11

Post by kens »

kipchak wrote: post #9

If you're interested in the history of the Titan missile program and US nuclear program in general I recommend "Command and Control: Nuclear Weapons, the Damascus Accident, and the Illusion of Safety".

I definitely agree with your recommendation. Much of that book describes the Titan missile that blew up in 1980 after someone dropped a wrench socket that punctured the rocket's fuel tank, throwing the 9 megaton warhead 100 feet. (The warhead did not detonate.) What I didn't realize until I visited the Titan museum near Tucson is that it wasn't a regular wrench socket, but a big, fist-sized 8-pound socket. This made it much more understandable how the socket put a hole in the missile.

Re: Inside a Titan missile guidance computer

#13

Post by DonHopkins »

kator wrote: post #7

I was just thinking, imagine trying to use a modern-day smartphone for this. So much complexity how could you be sure the missile would even get off the ground. There is a big advantage to systems that engineers can mostly "keep in their heads". Very few systems are that way these days.

THAT is not a computer. THIS is a computer.

https://www.youtube.com/watch?v=Kki-qo3GrNE

Re: Inside a Titan missile guidance computer

#15

Post by dmix »

pvg wrote: post #4
dmix wrote: post #2

This is another good read about using automated terrain mapping for cruise missile guidance systems. https://en.wikipedia.org/wiki/TERCOM Notably how it fit on older computer systems with limited memory by only sampling the terrain using a predefined path which a plane will travel over with imaging sensors beforehand. For minutemen style systems with predefined targets it would work well as the terrain won’t change s…

Isn't it an example of a highly guided missile?

Yes that’s correct, I meant compared to more controlled guidance by wire, radiation, satellite, etc. I phrased that improperly.

Re: Inside a Titan missile guidance computer

#17

Post by beerandt »

kens wrote: post #8
rgovostes wrote: post #6

I visited the Titan Missile Museum in Tucson, AZ, where you can see the control room from which the missile could have been launched. > At launch, orders from the National Command Authority would have specified one of three pre-programmed targets which, for security reasons, were unknown to the crew. ... Target 2, which is classified to this day but was assumed to be within the borders of the former Soviet Union, was…

Yes, the Titan museum is very interesting and I recommend it. I wondered the same thing about the punched tape, if I could extract the coordinates from it. I read somewhere that they were extremely strict about keeping the targets secret; before any maintenance on the computer, a special team came in just to ensure that the coordinates were erased from memory. It would have been a huge oversight if they didn't encryp…

Y'all are overthinking it- true lat long "coordinates" would be meaningless to this computer. What was fed into the computer (ahead of time) was a series of firing instructions (per target for 3 targets), calculated to take into account the launch site of each missile. (Core memory values persist long term, even through power outages, hence the need to manually erase values before maintenance.)

So even two missiles/warheads launched from different sites at the same target would have different guidance instructions.

You'd need to do some major reverse engineering and geodetic calculations even after decoding targeting punchcards to figure out what the actual targets were.

The punchcards used to select the target during launch are simply instructions to execute "target stored in memory 2" or something similar. The minutemen would not have had the ability to change the set of targeting options programmed in the missile, only select one of the pre-programmed options.

Re: Inside a Titan missile guidance computer

#18

Post by DuskStar »

serf wrote: post #12

I'm surprised they opted to use a passively cooled power supply. I imagine it was much heavier than an equivalent active system. I guess MPG doesn't matter much on a Titan missile.

I'd guess the opposite, actually. Mass is extremely important for a rocket, so there would be strong incentives to make the cooling system as light as possible.

But a passive system has a few major advantages - it's maintenance free, unlike an active system (imagine having to fill up the coolant tank before launch), and perfectly reliable. Sure, a phase-change coolant might be more efficient - but with flight times in the hours I'm not sure that the difference would be enough to compensate for the complexity.

Re: Inside a Titan missile guidance computer

#19

Post by ip26 »

kator wrote: post #7

I was just thinking, imagine trying to use a modern-day smartphone for this. So much complexity how could you be sure the missile would even get off the ground. There is a big advantage to systems that engineers can mostly "keep in their heads". Very few systems are that way these days.

I can't imagine trying to discover & isolate faults on something like this though.

Re: Inside a Titan missile guidance computer

#20

Post by pvg »

dmix wrote: post #15
pvg wrote: post #4

Earlier quoted context omitted.

Isn't it an example of a highly guided missile?

Yes that’s correct, I meant compared to more controlled guidance by wire, radiation, satellite, etc. I phrased that improperly.

Fun tangent - the most unguided missile ever.

https://en.wikipedia.org/wiki/AIR-2_Genie

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