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

Ian Andrew Bell (FoRK) < fork at ianbell.com > on > Tue Mar 7 14:59:28 PST 2006

Kevin;

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.

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.

The Blackbird and its predecessor the Oxcart might've had some  
primitive jammers (actually according to the flight manual it was  
more oriented towards pinpointing the missile) but fundamentally they  
had physics on their side.

-Ian.


On 7-Mar-06, at 11:20 AM, Kevin Elliott wrote:

> At 09:24 -0800  on  3/7/06, Ian Andrew Bell (FoRK) wrote:
>> The SR-71 was designed after Francis Gary Powers got shot down in his
>> U2 as a hard-to-hit Mach 3+ spyplane which could penetrate the Soviet
>> Union, outrun fighters and missiles, and be a little bit stealthy.
>> Standard procedure for Blackbird pilots when a missile locked on to
>> them was to hit the gas and out-accelerate the missile.  The SR-71
>> was totally uneconomical and was stood down in 1989 but has been used
>> intermittently by NASA for high-altitude research, MACH testing,
>> etc.  Other systems like the supposed Black Star would have similar
>> benefits to the SR-71, flying so high as to be practically impossible
>> to hit and being flexible and unpredictable; but with the added
>> benefit that it likely wouldn't be detected by most of the nations it
>> was interloping on.
>
> The SR-71 was built to solve a particular problem- how do I avoid  
> being shot down?  Solving the problem today we arrive at a TOTALLY  
> different solution.  The SR-71 is ANYTHING but stealth.  It's big,  
> incredibly hot, and was built long before stealth was well  
> understood or possible.  It's REPEATEDLY been shot at.  During the  
> 80's it was used to do damage assessment over  Libya, and came  
> under heavy SAM fire.  It's design was significantly more  
> complicated that "out-run the missile"- one of the major roles for  
> the second man in the cockpit was radar analysis and jamming to  
> avoid missile attack. Working the physics, it should be pretty  
> obvious that "out-running" the missile was a losing proposition in  
> the long run- eventually integrating SAM radar, creative firing  
> patterns, and better missile design would have lead to someone  
> shooting it down.
>
> So what replaced it?  My money is on something incredibly stealthy.  
> If you compare the F-117 and the B-2 bomber it's very clear that  
> the US has a VERY deep and detailed understanding of stealth.  A  
> aircraft the size of the F-117 (or slightly bigger), but with the  
> stealth technology of the B-2 would be quite invisible.  At the  
> very least I don't see any reason why their wouldn't be a spy  
> version of either aircraft (F-117 for cost and size, B-2 for range  
> and altitude). Either aircraft would be superior to the SR-71.  The  
> only thing better than real time photography is real time  
> photography no one knows you have.
> -- 
> ______________________________________________________
> 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)
> ______________________________________________________
>


More information about the FoRK mailing list