Dec 032017
 

An updated version of a post from a few years ago with obsolete formatting, with added editorial bloviation!

Point of note: 1963 is 54 years ago. With all the advances in the last half century, America still relies on the Minuteman. Since the Minuteman was developed, we also developed the Midgetman and Peacekeeper ICBMs… and got rid of them.

Note as well that the five year development time for the original Minuteman is  year and a half longer than the time since I originally posted another version of this old Minuteman video. And in that three and a half years, the United States does not seem to have developed a new ICBM, while in that time the North Koreans and Iranians *have.* The Russians have tested updated versions of the “Satan” ICBM (the RS-28 Sarmat), which carries 10+ warheads; the Minuteman III currently mouldering in American silos were designed for a whopping 3 warheads, but now carry a grand total of *one* warhead due to treaty restrictions.

 

Also of historic note: when the Minuteman was developed, a lot of components that, were they to be developed today, would be digital were then analog. The safe-and-arm for the solid rocket motors was essentially a heavy chunk of clockwork. The S&A simply served the purpose of making sure than an accidental electrical or mechanical discharge somewhere, if it inadvertently set off the ordnance lines leading to the motor igniter, would not actually get to the igniter. They are simple mechanical blocks that prevent the signal from getting through unless they are properly activated.

The Minuteman S&A’s worked well enough. So, when Thiokol was developing the solid rocket boosters for the Shuttle, they used the Minuteman S&As. And since once something is designed and fielded at NASA it almost never changes, the 1963-vintage S&As stayed with the RSRMs throughout the lifespan of the Shuttle. Last I knew, they were also in use on the five-segment boosters to be used on the “next generation” Space Launch System.” So *if* the SLS gets built (doubtful) and flies for decades (doubtful), the relatively ancient Minuteman S&As will probably fly with them throughout the SLS’s lifespan. If SLS flies in 2020 and lasts 20 years, the Minuteman S&A will have an 80 year operational life. Of course, by the time the SLS is retired, the Minuteman ICBM itself might still be in service.

 Posted by at 3:45 pm
  • Snoopy

    Yo dawg, did you see the rumors that the Nork quakes were caused by a fully operational Thor/Rods from God strike? Could the X-38 carry Rods up there?

    • Scottlowther

      > Yo dawg,

      Ummm… no. Just no.

      > did you see the rumors that the Nork quakes were caused by a
      fully operational Thor/Rods from God strike?

      No.

      > Could the X-38 carry Rods
      up there?

      Tiny little ones. Maybe capable of taking out a truck. Quakes, on the other hand, have the power of nukes, and there’s no such thing as a Rod from God design with the power of a nuke.

  • Snoopy

    X-37B I mean.

  • Garrai

    Fifty years is a long time for things with rubber/plastic insulation, bent tubing, lightweight aluminum brackets, solder joints, etc., etc. No way these missiles can be fully inspected other than the few parts that were designed to be field replaceable. And that big slug of rubber propellant? A few cracks in the grain and the warhead will end up in farmer Ted’s pasture instead of Noginsk.

    • sferrin

      “And that big slug of rubber propellant? A few cracks in the grain and the warhead will end up in farmer Ted’s pasture instead of Noginsk.”

      Where even to start with this? Demonstrated reliability is excellent. ANY solid grain that had a crack would have a similar problem. It’s not like this stuff is as brittle as a black powder Estes motor.

      • Scottlowther

        > ANY solid grain that had a crack would have a similar problem.

        Depends on the propellant. Minuteman propellant should be tolerant. Some Soviet/Russian propellants, however, were *not.* CSB: when i worked at United Tech circa 2003, a co-worker was getting ready to go to Russia to witness an ICBM refurbishment plant. A few days before he was to leave, however, the trip was cancelled because the plant went kerflooey. One of the things thy had there was a propellant wash-out robot… basically a robo-arm with a high pressure water cutter on the end. It would reach in through the nozzle and chop up the solid propellant grain. Concept works like a champ in the US, but they turned it loose on an old Soviet missile and BLAMMMO, the propellant *detonated.*

        The reason for that came down to chemistry. Most modern solid propellants are *basically* aluminum powder fuel, ammonium perchloride oxidizer and rubber to glue it all together. There are small quantities of other stuff: cyanoacrylates (“superglue”) to speed up the curing process for the rubber, iron oxide as a burn rate modifier (basically it works like thermite, mixing with the aluminum powder, to heat up the reaction and get things to go a bit faster).Most sane rocketeers use some form of extremely fine rust as the iron oxide. The Soviets, however, used ferrocene, which in it’s normal state is a liquid. This means its a whole lot easier to mix well with the rubber. And it works great as a burn rate modified. Problem: it stays a liquid. Even after the rubber has set solid and the missile has been left in a silo for years, the ferrocene is still a liquid, theoretically trapped in the matrix. In reality, it *slowly* migrates towards surfaces. It will pool up in cracks and along the bore. So when Crow T. Russian Robot reached in and hit the surface with a blast of water, the ferrocene along the surface layer caused the burn rate to go *stupid* high, and boom goes the dynamite.

        United Tech had its own experience with ferrocene.Some years before I got there, a small propellant magazine with old test slugs of propellant was to be cleaned out. The propellant, basically cylinders something like 3-4 inches in diameter, ~8 inches long, were to be taken off the shelf, put in a cart, moved to a burn pit, set on fire. Simple enough. However, the tech doing this got sloppy. Long experience had shown him that propellant slugs are perfectly safe; it was just fine to simply drop the slugs into the cart. Sadly, these were *ferrocene* laden test slugs, some years old, twitchy as hell. As memory serves, he did not survive the experience.

        • FelixA9

          I thought the typical behavior with a crack is that, due to it’s sharp apex, as the newly exposed surface starts to burn it forces the crack larger, exposing more surface area, forcing the crack deeper/wider, etc. until *BOOM*

          • Scottlowther

            Yes. No. Maybe. Depends. Cracks are to be avoided for just that reason. However, in reality what happens with a lot of cracks is that chamber pressurization will cause the two sides to be pressed against each other, disallowing flame propagation down the crack. Keep in mind, combustion doesn’t occur *in* the propellant, but actually a fraction of an inch *above* the propellant. The propellant is boiled and vaporized by the radiant heat from the flame above, and that’s hard to get going in a crack.

            Of course, that’s not a safety feature you want to rely on. Get that crack geometry wrong, such that the pressure or “wind” will actually pry the crack apart (create a “flap” of propellant), and things get sporty in a hurry.

  • Thucydides_of_Athens

    It seems the idea of ICBM’s is somewhat overshadowed these days with dreams of hypersonic cruise missiles or boost/glide systems, at least in USAF circles. Who knows, maybe they are really onto something?