[FoRK] archives: blackstar, the supposed two-stage spaceplane

Kevin Elliott < K-Elliott at wiu.edu > on > Wed Mar 8 08:59:39 PST 2006

At 14:59 -0800  on  3/7/06, Ian Andrew Bell (FoRK) wrote:
>The Blackbird was indeed designed to be stealthy, built by the same 
>team that designed the F-117a.  The chines stretching from the 
>leading edge of the wing
>to the tip of the nose are a rather unsubtle clue that the A-12 and 
>SR-71 were the first attempts at a production stealth aircraft and 
>worked effectively to
>reduce the radar signature.  That they also contributed to the 
>stability of the airplane and the shortening of the wings was a 
>lateral benefit, as it was the radar
>engineers and not the aerodynamicists that recommended the design. 
>It didn't work, but the reason why had nothing to do with the 
>airframe.  At the time this
>was being built it occurred to no one that the engine exhaust 
>itself, at a high enough temperature, became a reflective surface 
>and consequently the SR-71 was >a big blip on most long-range 
>radars.  This was "fixed" on the F-117, by making both it and the 
>B-2 subsonic (which means less heat).  For the SR-71 heat on >the 
>fuselage is not really a big factor since they're not often in range 
>of heat-seeking SAMs fired from the shoulders of Afghans, or 
>heat-seekers fired from the >wingtips of subsonic fighters -- Radar 
>Cross-Section is everything, and that big bubbling mass of 
>super-heated air behind the plane gives off a big one.

I should have been more clear on the stealth aspect- the SR-71 is 
clearly an early place where stealth ideas were applied, but it's not 
a stealth aircraft by todays' standards at all.

>Through most of the life of the A-12 (which was operational as a 
>single-seater) and SR-71 (which indeed had an RWO operating 4-6 
>different kinds of ECM)
>the stratagem upon warning of a missile contact were to hit the 
>throttle and execute a small turn.  At Mach 3.4 even a one degree 
>turn put you hundreds of
>miles off plot within seconds.  It wasn't until the 1980s that the 
>USSR even had a surface-to-air-missile that could travel fast enough 
>and high enough to
>potentially knock down an SR-71, though one never did.  If you've 
>got a missile system with a 300-mile radius then the Blackbird will 
>be over your head in
>less than 2.5 minutes, during which time you've gotta get a large 
>projectile 80,000 feet into the air.  You've got to be able to make 
>that missile accelerate to
>Mach 1 straight up within a few seconds of when it leaves the 
>launcher.  Do the math.

Indeed.  Hence the MIG-25/31 development.  I agree that during the 
time it operated it was never seriously threatened.  However, I 
firmly believe that one of the major reasons for it's withdrawal from 
service was the  realization that as technology evolved it would be 
threatened and eventually shot down.  It was simply to visible a 
target and to provocative.  How does the runaway scenario deal with 
multiply targeted missiles coming from different directions?  Run 
away only works if it's not forcing you toward a different threat.  I 
suspect it was retired because of evolving vulnerability concerns and 
because stealth had evolved to the point that it made for a more 
sensible platform.
Arguing with an engineer is like wrestling with a pig in mud.
After a while, you realize the pig is enjoying it.
Kevin Elliott   <mailto:kelliott at mac.com>
AIM/iChatAV: kelliott at mac.com  (video chat available)

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