In war, The enemy’s surveillance is crucial. In ancient times a person would do this, but now in the 21st-century, humans have developed planes to do so. Miles away in the air, the reconnaissance planes effectively obtain enemy intelligence.
The SR-71 is a strategic jet reconnaissance aircraft of the U.S. Air Force. Many advanced technologies were used to build it, including titanium structures and turbojet/ramjet variable cycle engines. This aircraft was the first jet to break through the thermal barrier; what is a thermal barrier?
“One of the limits to the speed an aircraft can fly. Exceeding the limiting speed can result in damage to the structure. A thermal barrier is generally related to aircraft flying at low levels at very high indicated airspeeds. ”
The SR-71 reconnaissance aircraft was developed in 1963, first flew in 1964, and served in 1966. A total of 32 were produced. Retired in 1990, partially reintegrated into the army in 1995, performed tasks in 1997, and permanently retired in 1998.
Why is the performance of the SR-71 “Blackbird” so strong?
In addition to the engine, the fuselage material is also essential. We know that the Soviet MiG-25 can also fly at speeds above Mach 3, but it’s difficult to maintain it for more than a few minutes if done for a longer time then high speed causes the higher temperature generated by friction, and if the material is not too hard, then the aircraft’s body could be damaged.
But The SR-71 “Blackbird” can do it because 90% of its fuselage is made of titanium alloy. When the SR-71 “Blackbird” is usually flying, the aerodynamic friction will cause the airframe temperature to reach 250 degrees Celsius, which can soften the lead.
We know that the hottest part of the aircraft is the nozzle at the rear of the engine. When aircraft is flying at a speed of more than Mach 3. the area around the engine’s nozzle gets heated as high as 510 degrees which can completely vaporize the lead.
Aircraft made of ordinary materials may be deformed and disintegrated or can ignite under such high temperatures. However, the SR-71 “Blackbird” body adopts high-strength titanium alloy, and it is effortless to cope with a high temperature of more than 500 degrees.
At such high temperatures, the use of ordinary fuel would have burned the plane long ago. Therefore, the SR-71 “Blackbird” uses JP-7 fuel with a high ignition point and high grade, which is difficult to ignite even with an open flame. But no matter what fuel, the flight speed is proportional to the fuel consumption. The faster the flight speed, the more fuel consumption.
Generally speaking, the SR-71 “Blackbird” needs to be refueled about every one and a half hours of flight, but because it flies so fast, it can fly a distance of about 4,500 kilometers with one refueling.
The SR-71 “Blackbird” is a great aircraft, and the tanker is also dedicated.Two SR-71 ” Blackbird “requires three kc-135Q tankers.
The SR-71 reconnaissance aircraft used radar absorbing materials and consciously used inward-inclined double vertical tails to prevent the right-angled interior angles that enhanced the reflection of radar waves.
The SR-71 is 32.74 meters long, with a wingspan of 16.94 meters and a height of 5.64 meters, with a wing area of 167.23 square meters. The whole machine has an empty weight of 33,500 kilograms.
SR-71 has a Take-off weight of 77,110 kilograms and can reach a maximum speed of Mach 3.2 in level flight, Mach 3 in cruising state, and a full range of 4,830 kilometers. It has a combat radius of 1,930 kilometers.
The SR-71 is powered by two Pratt & Whitney J-58-1 variable cycle engines, each producing 145 kN of static thrust. The SR-71 was once the fastest human-crewed aircraft in the world, but the high cost became the main reason for its retirement.
SR-71s are very expensive to make, at $34 million for a single plane, and even more costly to use them. It uses a special fuel known as JP-7 because the airframe gets so hot when the aircraft is flying at Mach 3. Regular aviation fuel will spontaneously ignite in the fuel tank. The JP-7 has a higher flash point, up to 150 degrees. It also needs an injection of nitrogen to help it stop burning. This means that the SR-71 needs to have a dedicated fleet of KC-135 tankers that can handle JP-7 fuel.
When it’s on the ground, the loosely assembled titanium plates required for significant expansion and contraction mean that every SR-71 leaks oil, and one sees a big puddle of oil underneath the plane. Fortunately, it is difficult to ignite because JP-7 can withstand high temperatures. In fact, to start the engine, people use a highly toxic and dangerous pyrophoric fuel, TEB, which burns on contact with air.
The black paint was designed to dissipate heat, which gave it its Blackbird moniker and combined with the sleek lines of the long fuselage, the plane didn’t look like anything before – this design hasn’t lost it in the least of brilliance.
“It still looks like something from the future, even though it was designed in the 1950s,” said aviation historian and author of “The Design and Development of the Blackbird” Peter Merlin. In a twisted way, it looks more organic. Most conventional planes look like they have man-made; this one almost looks like it grew out of itself.”
Successor of U-2
In May 1960, an American U-2 spy plane was shot down while taking aerial photos over Soviet airspace. At first, the U.S. government said it was a stray meteorological research plane, but once the Soviet government released pictures of the captured pilot and the plane’s surveillance equipment, the U.S. claim fell apart.
The incident had an immediate diplomatic impact on the Cold War. It reinforced the need for a new type of reconnaissance aircraft to fly faster and higher without being attacked by anti-aircraft fire. “The CIA wanted an aircraft that can fly above 90,000 feet or about 90,000 feet, at high speeds, and as undetected by radar as possible,” Merlin said.
The task of designing such an ambitious machine fell to Clarence “Kelly” Johnson, one of the world’s greatest aircraft designers, with his secretive engineering department at Lockheed “Skunk Works” started developing the aircraft. Everything has to be invented. “That’s all there is to it,” said Johnson, who died in 1990, the same year the Blackbirds retired for the first time.
The original Blackbird aircraft was named the A-12 “Oxcart” and made its maiden flight on April 30, 1962. It adopts a delta wing layout, a large edge is arranged from the leading edge of the wing root to the nose, and the two engines are placed on the left and right sides of the wing. And can fly at Mach 3. A total of 13 A-12s were produced, and the program is a top-secret program run by the CIA.
Because the plane was designed to fly at speeds above 2,000 miles per hour, friction with the surrounding atmosphere would heat the fuselage enough to melt conventional airframes. So the plane is made of titanium, a metal that can withstand high temperatures and is lighter than steel.