Retrotechtacular: Rocket Sleds

If you need to test rockets, missiles, or ejection-seat systems, your first instinct would be to shoot them up in the air and see what happens. But if you want data, film footage, or the ability to simply walk away from a test, you might consider running your experiment on a rocket sled.

The Holloman High Speed Test Track is a 15 km long stretch of meticulously straight railroad track located in the middle of the New Mexico desert, and bristling with measurement equipment. Today’s Retrotechtacular video (embedded below) gives you the guided tour. And by the way, the elderly colonel who narrates? He doesn’t just run the joint — he was one of the human test subjects put on a rocket sled to test the effects of high acceleration on humans. You can see him survive a run around 1:00 in.

The video isn’t all that long, but it’s slow-paced. High points include the water braking system in the first few minutes. The “momentum exchange technique” is secret code for filling the space between the tracks with water and ramming a scoop into it, throwing water forwards and thus slowing the sled down.

At 10:40, there’s an almost bizarre transition to dream-like slow motion sequences of various rockets making their runs. Great stuff. In between, there’s a lot of detail about the multiple cameras, light-break sensors, and other instrumentation that was state of the art in the 1960s.

Holloman is still in use today, as far as we know, which makes this Retrotechtacular a bit more contemporary than usual. The fastest run took place in 2003 at Mach 8.6. Not bad for some strips of metal dating back to 1949.

We can’t leave the subject of crazy rocket sleds without mentioning these mental Swedes or The Black Beetle.

28 thoughts on “Retrotechtacular: Rocket Sleds

  1. It would be fun to watch a test firing live. What would be nice is if we built a rocket sled track up a mountain aimed eastbound. That way, you could use a sled to throw a spaceplane up there to continue up into orbit. The Germans cooked up an idea damn near exactly like that: The Silbervogel. Look up “skyramp” on Google for details on this concept.

    1. That can’t be any more efficient than the current solution of “get close to the equator and point up, execute roll at altitude, and insert into orbit.”
      And isn’t that a side goal of the various hypersonic projects out there?

        1. I wouldn’t hold your breath on that one, it’s an even more difficult engineering challenge than hyperloop as you would have to build the exit of the vacuum launch tube up high enough so that the atmospheric pressure doesn’t ruin your vacuum. Now there is such a thing as a “plasma window” which can hold atmo on one side and vacuum on the other but so far they have only been able to demonstrate one big enough for a hole in the millimetre domain. But saying you could build one big enough, I’m doubtful that we would be able to build a spaceplane strong enough to handle the sudden force of transitioning between vacuum and atmo, though I guess you could gradually reduce the vacuum as you get closer to the exit. We could build one on the moon though without much difficulty, if we can get the materials up there. I’m putting my money on the space elevator for now, still a big engineering challenge but within our reach in the foreseeable future I feel.

          1. You’d just need something strong but brittle for the exit. Have the vehicle smash through it on the way out. Maybe safety glass. You’d need a pointy hammer on the front of the vehicle, and it would take some velocity from it (wouldn’t have to be much though). Safety would be a worry, but that’s solved just by testing and re-testing.

            The air rushing in as the vehicle leaves might also be a problem. But these can be solved! Still might work out better overall just to make the vehicle aerodynamic, forget the vacuum, and just deal with the air resistance by putting more thrust in.

  2. These retrotechtacular videos are probably one of the good features of HAD.

    Though couldn’t resist the inner child of ” … Two pounds of retarding force.”
    Sounds like a fight.

    BTW that phrase was from when they describe the water braking system.

  3. In the ’70s I participated in sled testing at the 4-mile long track at China Lake test facility. Called the Supersonic Naval Ordnance Research Track (SNORT), we were testing solid fuel missile rocket motors and IR seekers similar to this video. They used a small electric cart to push the sled back to the starting position. On one the of the runs, the seeker came back smashed and bloody. Seems it hit a flock of birds during its run at close to Mach 1. Completely damaged our test article. This track was one of the first, built back in ’53. See for info.

    1. I think he said plus or minus 5 for the guide track, and the other track was within .01 of the first track. How in the world could they get it that straight and then keep it that straight over the years? Amazing. The balancing on the sleds must be perfect, too. If a nose cone is a hair off, it’s going to want to pull to one side.

      A fun film to watch.

        1. Even more impressive considering the heat and thermal expansion. Go a hedge that no one really checked it that closely, more like ‘fuck it, if it goes bang blame it on the hardware’.

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