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Introduction
In 1955, the U-2 went on it's first test flight and would be utilized in conducting reconnaissance operations over the USSR during the Cold War. It could fly high and take great photos, however the U-2 was not stealth. The Soviet Military knew when and where it was flying over it's territory at all times and in 1960, the Soviets finally shot down a U-2 being piloted by CIA agent Gary Francis Powers on a routine surveillance mission.
Gary Powers was publicly trialed and the United States was deeply embarrassed by this incident. The U-2 wreckage was recovered by the Soviets in relatively well condition with even the on-board cameras intact and would be paraded around for all to see. The United States was in need of a way to spy on Soviet territory without opposition.
Fortunately for the US, legendary aircraft designer Clarence "Kelly" Johnson had already been working on designs for their answer. A strategic reconnaissance aircraft with stealth and could fly high and fast enough that nothing could dare disturb it while it worked. Nothing could catch it, nothing could hide from it and it would leave it's mark on history as one of the single greatest planes to have ever been designed.
Airframe & Engineering
When going at the speeds the Blackbird would be, the airframe would be under heavy stress and heat from the air friction. Other incredibly fast vehicles have found ways to mitigate these issues. The X-15 would use a specially designed heat-sink type skin while the Space Shuttles would use ceramic tiling. The Blackbird needed a solution and it would get it.
The Blackbird would find it's solution in the material used in it's construction. Aircraft are normally built using aluminum as it's lightweight and all around perfect for aviation. Aluminum, however, handles heat very poorly. So to help solve their problems, aluminum would be replaced with titanium. It's both lightweight and heat resistant with the added benefit of being extremely strong & durable but there were 2 things being compromised for those benefits.
At that time, the largest producer of titanium was, ironically, the USSR. If the US wanted to have enough titanium to construct these airplanes, the titanium had to come from the USSR. To do this, the CIA would create multiple false companies as fronts to source the titanium and purchase it over time, this way the Soviets would not notice and be none the wiser. The second compromise was time. Titanium has incredible heat resistance while also being both strong and durable. This of course also means it's extremely difficult to work with so it would require special tools and more time needed to construct these Blackbirds.
Despite the compromises, Kelly Johnson would not only deliver the Blackbirds to the US Government way ahead of schedule but also millions of dollars cheaper than the original projected costs. It's safe to say the military was in love with him by this point.
SR71Structure2
SR-71 Blueprints
SR71 Blueprints
Technical overlook of the SR-71A airframe
J58 I
Technical overlook of the J-58 turbojet engines
SR71 II
SR-71-BlackBird
SR71 Camera I
SR-71 Astroinertial Navigation System (ANS)
Kelly Johnson I
SR71 Instruments I
SR-71 Astroinertial Navigation System (ANS)
Engines Engineered by Energized Engineers
The Blackbird used twin Pratt & Whitney J58 afterburning (continuously) turbojet engines (JT11D-20). Each engine could output around 30,000 Lbs. (13,607 Kg.) of thrust on full afterburner and the two inlet cones, tipped off with solid titanium spikes, were able to retract automatically according to the aircraft's airspeed. Below is the aft position correlated with airspeed:
Mach 0 - Mach 1.5 (0MPH - 1150 Mp/H / 1850 | Km/H) = Fully retracted back
Mach 1.5 - Mach 1.9 (1150MPH - 1457 Mp/H | 2344 Km/H) = Middle position
Mach 1.9+ (1457 Mp/H+ | 2344 Km/H+) = Fully extended forward
Most super sonic aircraft produced 1 single sonic boom when breaking the sound barrier. The Blackbird, however, produced 2 sonic booms. This is because both the nose and the inlet cones on the engines would break the sound barrier, the cones breaking it just shortly after the cone since they were farther back in relative distance to the nose. The result was two distinct sonic booms.
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Dual Sonic Boom
Astroinertial Navigation System - "R2D2"
The SR-71 was operational long before GPS or any serious satellite infrastructure existed. Maps are rendered useless at the edge of space and the Blackbird needed something to know where it was, so it was installed with a special set of sensors and a camera that was placed on the top of the aircraft so it could use the stars to navigate.
The ANS system, affectionately named "R2D2" by the flight crews, would pick two stars and track the Blackbird's position relative to them to give precise location information. The camera was sensitive enough to be able to see the stars even in bright daylight.
Variants, Equipment & Arsenals
SR-71A Blackbird "Long Tail"
The SR-71A #61-7959, nicknamed "Long Tail", was a variant of the Blackbird created due to arising misplaced concerns the United States Air Force had of future ground forces being able to fire on the aircraft from behind. So to future-proof the SR-71, they decided adding some new sensors and equipment would be best. This included an ECM package (Electronic Countermeasures) such as missile and radar jamming as well as things like a new 24" Optical Bar Camera to aid with seeing targets in severe weather.
The USAF had concluded the best place to put all of this new equipment without affecting performance was in the back by extending the tail. The new tail extended 13 ft. 9 in. long and was raised slightly by 8.5° for take-off ground clearance. It could carry an additional 864 Lbs., making the entire tail assembly weigh a total of 1,273 Lbs.
61-7959 was built on the Lockheed Martin assembly line with all her other sisters but was kidnapped upon completion to serve as the testbed for the new tail. Flight tests have shown though that the new sensor suite provided little more advantage and that the SR-71 already had everything it needed. The project was abandoned and she was the only one ever built.
If you wish to see her, she now resides at the Air Force Armament Museum located at Eglin AFB in Florida.
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