Sunday Funnies: Speed Check

I remember hearing about this back in the USENET days. It’s a fun story and he’s obviously told it many times.

(the audio is meh, turn up the volume)

I think it’s funny that Shul says people ask “was it fun to fly The Jet?” That has to be one of those rare questions that is, actually, a stupid question.

Some numbers (I think I have this right):

  • 2000knots is about 3300 feet/second
  • A .308 bullet’s typical muzzle speed coming out of a bolt-action rifle is about 2600 feet/second.

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The SR-71’s engine was a madhouse thing. Think about this: they designed it before CAD was available. Figuring out the fluid dynamics in that thing had to be done with coffee and brains.

It’s amazing what can be done when you have a bottomless money supply.


  1. says

    And some of the earlier proposals for that program were even more cutting edge. An earlier Lockheed design, the CL400 Suntan, was planned to be powered by liquid hydrogen engines, but was cancelled due to range questions and the complications of handling and shoring liquid hydrogen.. The US Navy and Boeing proposed inflatable rubber designs, and Lockheed’s Archangel 2 proposal was to use ramjets powered by something called zip fuel, which contained hydro-boron compounds.

  2. says

    This may warm the cockles of your heart, as I checked your conversion:

    $ units
    2411 units, 71 prefixes, 33 nonlinear units

    You have: 2000 knots
    You want: fps
    * 3375.6197
    / 0.0002962419

  3. says

    Think about this: they designed it before CAD was available. Figuring out the fluid dynamics in that thing had to be done with coffee and brains.

    And slide rules (hint, hint).

    I did drafting in high school. Thinking 3D on a 2D piece of paper required spatial awareness many people aren’t capable of.

  4. sonofrojblake says

    The thing that first blew my mind about the SR-71, back when I was a kid, was this: it was unarmed. It looked so threatening, so intimidating, but all it carried were cameras. At the same time I learned this: it didn’t need to be armed, for the mind-boggling reason that nothing anyone could fire at it could catch up with it.

    Shul’s got some good stories. Another of my favourites is the one where he gets in touch with ATC and requests clearance to FL800 (spoken “eff ell eight zero zero”: translation: I want to go into this bit of airspace under your control and I want to be clear to be in the bit of it that’s at 80,000 feet – fifteen miles up, more than twice the altitude any normal airliner flies and an altitude where any normal engine won’t work for lack of oxygen).

    The ATC guy, probably assuming some civil pilot had accidentally tacked on an extra zero, sarcastically asked how the pilot requesting clearance was planning to get up to 80,000 feet. To which Shul responded “I’m not planning on getting up to 80,000 feet. I’m planning on coming down to 80,000 feet.” He got his clearance.

    For sheer look-like-sixties-science-fiction, though, the SR-71 is comparable to only one aircraft IMHO – the XB-70 Valkyrie. I won’t rhapsodise about it – just look it up. A proposed Mach 3, 70,000ft capable nuclear bomber, they only ever built two, and only one survives. They featured the largest movable surface ever put on an aircraft – the end of the delta wings folded down to generate compression lift.

  5. says

    the XB-70 Valkyrie. I won’t rhapsodise about it

    Favorite XB-70 fact: the fuel tanks were used as heat sinks, which helped pre-heat the fuel so it burned better. It also made the plane into a flying bomb, but who cares?

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