May 312014

(Yes, yes, I ran this artwork a year ago. But I’m running it again, this time with more verbage & photos.)

A cutaway illustration of the KIWI-A nuclear rocket test unit. As shown here it is actually upside down compared to how it was tested; as with I believe all the other nuclear rockets that were tested, the nozzle fired upwards towards the sky. This rocket engine was not meant to represent a flight-capable system, rather just a basic proof of concept. And thus it was named after a flightless bird. Note that the hydrogen “propellant” is injected at the nozzle end of the reactor, travels forward through the graphite reflectors, then makes a U-turn and goes through the reactor “plates” that wrapped around a deuterium oxide central moderator. This is not at all like what later, more developed nuclear rockets like NERVA used.

Note that test firings on the KIWI system began in *1959.* That’s 55 years ago when we had the functional start of nuclear rocketry. Today we have… Powerpoint.



A photo of the test setup. The full-rez version is HERE.


KIWI firing. Note orange hydrogen combustion plume. This is not due to combustion within the engine, but due to superheated gaseous hydrogen mixing with the oxygen in the air and burning externally. Full rez HERE.


Probably the most entertaining test must have been the KIWI-TNT (Transient Nuclear Test)test. Here, a KIWI engine was put on a  rail car and allowed to go prompt critical, with the result being that the engine blew up with the approximate force of about 100 pounds of TNT. The nuclear fuel was uranium oxide, so it was already oxidized and very likely underwent little to no chemical change; but the graphite reflector was pure carbon. Pure *shattered* carbon. Pure shattered carbon at extremely high temperature. And thus it promptly caught fire int he air and burned, with the result you can see below:


The “sparks” should be chunks of reflector. The fireball would be hydrogen… *if* hydrogen was being pumped through it at the time. I’m not sure that it was, though.

 Posted by at 9:36 am
  • Anonymous

    This kind of thing just reminds me how screwed this country is. We’ve gone from actually testing nuclear rockets, ramjets, and bombs all WHILE working on getting to the moon and producing multiple Mach 3 aircraft designs to fiddling with old rocket engine designs just so we can shoot a man into space in a tin can again. How’s that for a half-century of “progress”.

    • Anonymous

      I’m thankful we are doing anything. I will say this much–we have seen more progress in liquid fueled rocketry than we have since the 1960’s, so that is something. I’ll take what I can get.

      The big story in recent years is how Griffin, Musk and others stood up to the Air Force jock-o-cracy, that reached its height with The Right Stuff, and how engineers were all but demonized in that. Space advocates are getting more and more aggressive with their agendas. We don’t have a Cold War that funds everything, and a new isolationism is taking hold.

      Space advocates need to exploit that to the full. The brits need to push for Skylon to get military funds, while killing F-35 might open a few things up.

      • Anonymous

        I was with ya right up to the “killing the F-35” part. That would be a bad idea for more reasons than I care to list.

        • se jones

          Unless you live in Fort Worth and work for LM — why?

          • Anonymous

            What the world needs: a space-capable version of the F-35. Replace the current jet engine with a smaller one. Use the excess volume created for rocket propellant storage. Add a docking adapter and a small pressurized volume where the lift engine is currently housed. Add a few decent rocket thrusters to the tail, RCS jets to nose, wings and tail. Coat underside and wings with heat shielding. Launch atop a Falcon 9 Heavy. Dock with ISS, pick up US staff, then stand off and pummel the US modules with cannon fire and space-modified versions of Sidewinders and Hellfires. Then return to a ticker-tape parade. Keep a squadron on standby near each *real* US space station to follow. Crew of the SF-35’s will be able to keep in good physical condition because these will be *proper* space stations with rotating sections, hookers and blackjack.

          • se jones

            Dang…that’s brilliant!

          • Anonymous
          • Anonymous

            It should be obvious. The F-16 is 35 years old. The Harrier older. The F/A-18Cs aren’t exactly spring chickens either. They need replacing. Furthermore their days of being king are long over so we need something better. That’s the F-35.

          • se jones

            They need replaced with upgraded new variants, but the JSF is an abomination both in performance and cost. This monstrosity is the epitome of pork projects, at $400+ billion it’s twice the cost of project Apollo in real dollars. This for a “fighter” with such a crappy p/w ratio that’s its time-to-climb is literally like flying an F-18 on one engine.
            Oh, but it has stealth. On a good day, it has the radar cross section of a small bird. Never mind, modern software & computers will notice right-away, a bird going 650 miles per hour. Then there’s bistatic radar, which – like the wind profiler radars I work on – will light up stealth a/c like a christmas tree.

            The latest JSF outrage ‘o the week, is – organizers of this summer’s big airshows in the UK noticed there’d be no F-35B flight demos as the AV-8s have been doing for years.
            Well, it seems LM has been glossing over the fact that that the hot section exhaust from the B model has a much higher dynamic pressure and temperature that the Harrier’s exhausts.
            Seems the F-35B will cause the concrete in ordinary mil grade concrete to “spall” (the residual water in the concrete will flash to vapor and explode off chunks) and of course standard airport mix has asphalt mixed in so that’s out of the question. The flying concrete chunks can damage the delicate stealth coatings and plethora of sensors and cameras.
            In order to use the JSF “B” in primitive forward combat areas, the marines will have to haul in 400 pieces (30 tons) of aluminum VL pads. Sort of defeats the whole purpose. Naturally, the enemy will be watching all this with their cheap UAVs and local observers.

            Keep the Warthogs flying, build the Super Hornet so the USA will have a/c we can actually USE in combat (outside of Utah) and take the money we save to pay down the national debt and build Scott’s space ferris wheels with hookers and blackjack.

  • Christopher James Huff

    “Coolant supply piping to the reactor shell was removed because non-hydrogen coolant-propellant was used. A point worthy of emphasis is that to achieve a reactivity insertion rate sufficient to vaporize a significant fraction of the core, the control rod mechanisms were modified to rotate at approximately 100 times the normal rate.”

    Also of interest:
    “The pressure vs. time relationships in the Kiwi-TNT event were unusual, but not unique. They are most nearly approximated by the explosion of black powder, one of the few explosive materials that acts by exothermic chemical reaction of physically mixed reactants rather than by exothermic decomposition of a chemical compound.”

  • se jones

    >>all the other nuclear rockets that were tested, the nozzle fired upwards towards the sky

    Nyet. The Los Alamos “Nuclear Furnace” tests and then the XE series were downward firing.
    Nuclear Furnace co-development programs were a scrubber system and the ETS-1 test cell to remove any eroded fuel element particles from the exhaust stream.

    XE series were “flight configured” engines with tankage on top and nozzle pointing down. XE-1 wasn’t run with propellent, but XE-2 (renamed prime) on the ETS-1 cell was the real deal, 3 HOURS 48 min run, 3 1/2 minutes at FULL power and 24 bootstraps.

    The ETS-1 cell with scrubber is still out there waiting.

    Wish we knew the truth: did Anderson kill the 2707 as retribution for cancelling NERVA? We may never know.

    The story of Anderson & the nuclear engine program would make one hell of a good screenplay along the lines of “Charlie Wilson’s War” if a good writer gave a damn. Letters to follow.

  • Joe

    And how much radiation was released in these lunatic tests?

    • Anonymous

      Surprisingly little. Especially surprising if you think that the tests were “lunatic” rather than proper engineering development.

    • Anonymous

      Not enough apparently.