Sep 132011
A Boeing painting depicting a 747 in the process of launching an MX-style ICBM. The total load was at least four such missiles. No further data than the artwork. A “bridge”-like cradle would go fore and aft carrying missiles and dropping them out a large hatch in the underside of the rear fuselage. Speculation: controlling the aircraft during the rather sudden shift in CG would have been interesting.
6 Responses to “Flying boomers 5: 747 MX launcher”
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Just pump liquid mercury back and forth to keep your weight and balance where it should be!
They might have pumped fuel forward and back between front and aft-mounted tanks; that’s how the B-1 and Concorde handled the shift needed in their CG as they went supersonic.
Problem is the timescale. The C-5 shove-it-out-the-back-door option moves the CG forward over a span of, what, a second or so as the missile slides out and imparts decreasing weight on the vehicle. The 747 drop-it option has a virtually instantaneous change in CG. Unless, of course, it’s not simply dropped, but comes down on swingarms or cables or something/
Perhaps the answer is in a combination of factors?
On the one hand, the C-5 extraction was a typical parachute extraction operation: starts slow and accelerates rapidly, so yes it is probably quicker than a slide-back-and-drop technique. But on the other hand, with the extraction method, the weight starts coming off the back at the end of the ramp (moment arm) when the CG of the package gets to that point (plus or minus depending on what the extraction chute is doing) .
Contrast that with where the mass comes off the launch vehicle much farther forward using the drop method.
Perhaps most important, the missiles shown are way too small to be a Minuteman much less an MX, based upon the known width limit of a full span container for the 747 is 121 inches, the diameter of the Minuteman III is 66 inches, and an MX diameter is 90 inches. Perhaps the smaller missiles shown are a new design or repurposed stages from another, smaller system?
Side note on CG shifts: My unit flight-tested cargo handling concepts for the C-17 in the 80’s. (we were out of Hill but part of AFFTC – UAV Test was our normal mission, bur we had C-130s so ended up doing a lot of weird stuff). One test involved extracting a ‘married’ pallet of 40,000lbs. Fortunately it was a high altitude test, because it became Mr Toad’s Wild Ride when the pallet jammed halfway out the ramp. Fortunately with enough pitch-up, the pallet came out. Interesting stall and recovery episode
Is it carrying “Midgetman” (Small ICBM) missiles? Those were fairly small in diameter (44″):
http://www.designation-systems.net/dusrm/m-134.html
Found some solid evidence this concept predated the Small ICBM (but it may have helped give rise to it I suppose). In FlightGlobal’s archives online, there’s an almost exact duplicate of the artwork above, the only difference I see is there is ‘MC-747′ on the vertical stab on the FlightGlobal image.’Flight International’ 7 March 1974 issue, Pages 309, 310 talk about the concept and the 747 concept art is on page 310. The missile payload discussed for this concept was 4 missiles/400Klbs (much heavier than SICBM). there are othe concepts discussed, including ‘sea-sitting’ amphibian aircraft that would deploy (shades of 40’s-50’s Navy ambitions) in crises.