Dec 172017

A few days ago I uploaded in the 2017-12 APR Patron Extras Dropbox folder a scan of an old magazine article on the X-24 lifting body which including this interesting piece of art depicting an X-24 atop a Titan IIIc launch vehicle. There were indeed proposals to launch X-24 derivatives into orbit with Titan IIIs, but they wouldn’t be *exactly* X-24’s. The X-24 was not built as a spacecraft or a re-entry vehicle; it would be uncontrollable outside the atmosphere and would be a molten collection of rubbish on re-entry. Still, the proposed vehicles did look a *lot* like the X-24.

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 Posted by at 12:32 pm
  • se jones

    Scott: to your knowledge, did any of the contractors build a full sized SRB with Thrust Termination Ports and do a live fire test of the thrust termination system? I’d love to see video of that test, but I’m guessing that even if such footage exists, after Challenger the contractor(s) would be reticent to make it public.

    • Scottlowther

      Built, tested and indeed flown. Early Titan IIIC’s had white circles on the SRB nosecones; these were the thrust termination ports. These were built because the payload the TIIIC was designed, built and paid for was the Dyna Soar. But when it became clear that the DS was dead, the thrust termination systems ceased to be of value or interest and they were deleted for cost and weight savings. Had the TIIIC flown with a manned payload such as the Gemini, Apollo or a lifting body, it’s probable that the TT ports would have returned.

      When I was at United Tech I recall seeing stills of full-scale tests of the TT ports. I don’t know if the motors were full-scale… they might have only been a couple segments bolted together. Full diameter but short length.

      • se jones

        Thanks Scott! Tis a pleasure to learn something new, the day’s not wasted.
        If you ever find video of a test, I will pay $ just to see it. Hell, now I’m wondering if they might have even done a flight test of the TT system, that would be a sight to behold.

        • Scottlowther

          I don’t think I’ve seen a video of a Titan thrust termination. I *have* seen vids of other, smaller motors popping their TT ports (back in my UTC days, pre-youtube). They are pretty common on ICBMs; TT is a great way to manage trajectories when you have a solid rocket motor that you otherwise can’t shut off. It’s very useful for shorter-range flights. They were also used on upper stages of non-ICBM missiles, and for a similar reason, though offhand I’m not sure if I should go into details on that. Probably not classified but… shrug.

          Pretty sure TTP’s have been popped in flight, just not on the Titan.

          Would have been a sight to behold on the Shuttle booster; a number of early concepts called for the inclusion of Titan-like TT ports for abort scenarios.

          FYI: done right, a TT at altitude will not just cancel the thrust coming out the main nozzle, it will actually shut down the combustion process and the propellant will go inert. It’s been a good long while, but I recall that the number was something like 10 thousand PSI per second… if you can get the chamber pressure to drop that fast, the motor will actually blow out like a candle. This was achieved not only with TT ports, but it was also done several times with pintle nozzles: a small extension or retraction of the central plug massively increases the area of the throat and *POOF* out goes the motor. Put the pintle back into place, fire up another igniter and away you go again. The USAF wanted just such a capability for ICBM and ABM upper stages back in the sixties. I know I’ve posted some images on the blog about that…

  • Peter Hanely

    The X-23 used nearly the same shape as the X-24a for an unmanned reentry vehicle, so reentry characteristics of the shape are a known quantity.

  • Ulrich Brasche III

    Musk needs to build one of these for the Falcon Heavy launch.