Info on the SR-71 Blackbird

[Bruce FLinch]

Sorry, the Pics did not copy. But the Reading is good!

SR-71 BLACKBIRD INFORMATION

Last weekend at the museum of flight (Boeing Field, Seattle) was the 2007 Blackbird Forum. SR-71 pilots, reconnaissance officers, and crew chiefs discussed their experiences with the airplane and answered questions. The capabilities of that airplane built with 1960 technology are mind boggling.




The engine is a masterpiece. At mach 3.2, 75% of the thrust comes from the inlet. (The nose spike moves aft 26 inches.) Air pressure in front of the compressor increases from 0.5 psi to 14.5 psi over a distance of 5 feet, while internal airflow slows from mach 3.2 to mach 0.8 so the compressor blades can handle it without stalling. Bypass tubes divert extra air around the engine directly to the afterburner and cause it to perform like a ram jet.







Airspeed is not the limiting factor. At mach 3.2 a primary instrument is compressor inlet temperature. If it exceeds 427 degrees Centigrade, the compressor blades disintegrate. The pilot monitors the CIT and lets the airspeed take care of itself.

At mach 3.2, the titanium skin heats considerably. The fuselage stretches six inches. The fuselage is six fuel tanks. They leak all the time on the ground, but at altitude they heat up and expand, sealing the joints. After some fuel is consumed, the fuel still cools the bottom of the tanks, but is no longer in contact with the top. Therefore the top of the fuselage stretches more than the bottom, causing it to actually bend down somewhat at each end.

When the USSR shot down our U-2 in 1960, Kelly Johnson immediately realized we needed something higher and faster that no enemy could reach, so t he Skunk Works went back to the drawing board. The first flight was 22 months later. Try that today. We lost three out of 50 due to accidents. (One broke up after colliding with the drone it had just launched.) No enemy was ever able to touch it.

SecDef Robert McNamara ordered all the SR-71 manufacturing tools destroyed so he would have more tax dollars to waste on the F-111. In 1994 William Jefferson Clinton used line item veto to cancel all funding for SR-71s. They are now in museums. The pilots said that we really need that airplane today for reconnaissance over places like Iran, Iraq, Syria, Korea, China, Russia, etc. If it were not for Clinton, SR-71 would still be performing that reconnaissance today. The argument that satellites can do the job is not correct. Any school boy with a lap top can tell you when a satellite will be overhead, so the bad guys simply shut things down, and later restart them. On the other hand, the enemy never knows where or when the SR -71 will suddenly appear out of nowhere.

At 80,000 feet the cameras can see 80 miles. From 20 miles off the coast, the airplane can photograph objects 60 miles inland. The requirement for a rock solid gyro stabilized camera platform was paramount. My favorite analogy was this:

Nail a four foot square sheet of plywood to the bottom of the airplane. Drill a quarter inch hole through the middle of it. Insert a quarter inch dowel that is 16 MILES long. Drag the dowel across the surface of the earth at 30 miles per MINUTE.
Program the camera to take one photo per second of a specified set of coordinates for four minutes, in order to examine the spot from all angles. Do this in such a way that all photos are crystal clear, with no blurring.

Pilots, who are not trained as photo interpreters, say they can read the photos easily. One pilot looked at an Infrared photo of a USAF base and immediately recognized the shadow (heat signature) of a spot where a B-52 had been parked one hour earlier.

Celestial navigation is automatic. There are about 50 stars programmed into the computer. These stars can be observed by th e navigation system while parked on the ramp during broad daylight. Although the pilot takes off and lands the airplane manually, the navigation system is accurate enough to put the airplane on the runway in zero-zero conditions after flying nonstop from California to Iraq and return with four inflight refuelings.


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[berto64]

Another reason the klintoons should be run out of town on a rail after a tar & feather party. JMHO.

[LurpyGeek]

One thing I've found to be really interesting about it is (due to the inlet effects explained above), that the SR-71 is the most fuel efficient when it is travelling above mach 3.

[45nut]

It may have been 60's technology, but real thought went into it, not the PC sh!t we have to contend with today.