Airframe: The SR-71 Blackbird
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By Bennie J. Davis III, Airman Magazine
Following the loss of two U-2 Dragon Lady reconnaissance aircraft over the Soviet Union and Cuba in the early 1960s, President Lyndon Johnson demanded the seemingly impossible — a surveillance aircraft that could not be shot down by Soviet Bloc anti-aircraft missiles or interceptor aircraft.
To answer this Cold War need, the SR-71 Blackbird was born. The new photoreconnaissance aircraft evolved from the existing A-12 which was engineered by the preeminent aircraft designers of the twentieth century; Lockheed’s covert Skunk Works team led by Clarence “Kelly” Johnson.
The fledgling design provided the Air Force with a barrier-breaking aircraft to improve intelligence gathering in an airframe that could fly higher and faster than the U-2 with a reduced radar cross section.
The SR-71’s first flight took place on Dec. 22, 1964, and the first operational aircraft entered service with the 4200th Strategic Reconnaissance Wing at Beale Air Force Base, California, in January 1966.
A total of 32 aircraft were built.
The secrets of the SR-71’s ground breaking technology were so highly prized by foreign operatives that, in 1968, Lockheed was ordered by the government to destroy all tooling used to create and build the Blackbird.
During it’s 34 years of service, the SR-71 gathered intelligence in some of the world’s most hostile environments. The Blackbird evaded all 4,000 missiles fired at it and, to this day, remains the only Air Force aircraft to never lose a crewmember associated with it; whether in the air or on the ground.
An underside view of an SR-71 Blackbird strategic reconnaissance aircraft in flight at an undisclosed location.U.S. AIR FORCE PHOTO
Development and Design
The Blackbird was developed to fly over Mach 3 with a two person flight crew in tandem cockpits, one for the pilot in the forward cockpit and another for the Reconnaissance Systems Officer (RSO) who operated the cameras and surveillance systems, while navigating the mission path.
The Blackbird was designed to operate at extreme velocities, altitudes and temperatures. It was the first aircraft constructed with titanium, as the friction caused by air molecules passing over its surface at Mach 2.6 would melt a conventional aluminum frame. Its engineering was so cutting edge that even the tools to build the SR-71 needed to be designed from scratch.
The SR-71 was also the world’s first stealth aircraft.
To become nearly undetectable the aircraft had to take on a unique shape. The wings were blended into the body and the long blade-like surfaces along the forward fuselage, known as chines, aided in deflecting incoming radar waves.
The inward-angled twin fins over the engines and the pointed engine cones also decreased the Black Bird’s radar cross-section. The lower fuselage was nearly flat giving the 107-foot SR-71 its sleek and futuristic spear look.
The SR-71 was finished in a black ferrite (iron) radar absorbing paint. The paint made the aircraft even more difficult to target and aided in thermal protection due to 600-degree external temperatures caused by friction during flight.
The black paint also provided the spy plane the look for its official Air Force name, Blackbird.
Flying at altitudes above 85,000 feet and at speeds up to Mach 3.3, or 2532 miles per hour, the SR-71 became the highest flying and fastest jet in the world. It could fly from New York to London in under two hours.
The sleek needle-nosed spy plane with its swept double-delta wings was powered by two Pratt & Whitney J58 axial-flow turbojet engines, each providing 32,500 pounds of thrust – enough to power an ocean liner.
To produce this much power, the J58 engines guzzled 5,000 gallons of fuel per hour. The turbojet engines functioned as ordinary jets at lower speeds, but transitioned to ramjets at speeds above 2,000 mph.
To be selected to fly the SR-71, pilots had to be considered among the Air Force’s best and due to the altitudes they had to undergo the same rigorous physical training and examinations as NASA’s astronaut corps.
A group of SR-71 Blackbird Pilots from NASA in 1991. After the retirement of the SR-71 program with the U.S. Air Force, two Blackbirds were delivered to NASA as testbeds for high-speed and high-altitude aeronautical research.NASA PHOTO
The pilots also needed special protection to fly the aircraft and were outfitted with pressure suits and helmets that provided pure oxygen.
Five years into the Vietnam War, on March 21, 1968, the Blackbird flew its first operational sortie out of Kadena Air Force Base, Okinawa, Japan. The role of the SR-71 was to gather photographic and electronic intelligence of the enemy.
The pilots were provided high-protein, low-residue meals of steak and eggs three hours before each flight to provide energy for the rigors of flying the Blackbird and to reduce the need for a restroom at 80,000 ft.
SR-71 missions demanded perfection from the entire team of pilots, maintainers, mission planners and photo processors. There was no room for error due to the sensitivity of the intelligence and technology used in gathering it.
While flying above 80,000 feet, six different cameras or sensors on the Blackbird were able to photograph over 100,000 square miles in an hour. After each flight the camera’s film was unloaded, processed and analyzed immediately. The reconnaissance information gathered provided strategic awareness and advantage for the United States.
AnSR-71 Blackbird strategic reconnaissance aircraft being refueled by a KC-135Q Stratotanker during an aerial refueling training sortie. In order for the SR-71 to conduct missions it has to be refused multiple times by specially modified tanker aircraft to carry JP-7 fuel.PHOTO // MICHEAL HAGGERTY
During its active career, the SR-71 flew 257 operational missions, 942 sorties and amassed nearly 3,000 flying hours. Most operational sorties where flown from Kadena, but the SR-71 was also stationed at Royal Air Force Base Mildenhall, United Kingdom and Beale AFB.
Heading into the 1990’s it was determined the costs of maintaining the SR-71’s radar-resistant coating and ramjets fed by specialized supersonic JP-7 fuel and a tanker fleet to deliver it, made the airframe no longer sustainable. With advances in satellite intelligence and the lower cost of operating the technologically upgraded U-2R Dragon Lady, the SR-71 program was shut down.
On Nov. 22, 1989, the Air Force SR-71 program was officially terminated.
During its active career, the SR-71 flew 257 operational missions, 942 sorties and amassed nearly 3,000 flying hours. (U.S. Air Force photo)
Features and Deployment
Air Force units that operated the SR-71 Blackbird included:
– The 9th Strategic Reconnaissance Wing at Beale AFB, California.
– The 9th Strategic Reconnaissance Wing, Operating Location – 8 (OL-8), (later becoming Detachment 1) at Kadena AB, Okinawa, Japan.
– The 9th Strategic Reconnaissance Wing, Detachment 4, Royal Air Force Mildenhall, United Kingdom
Many altitude and speed records were set by the SR-71 and it still remains the fastest manned jet-powered aircraft in history. To celebrate America’s bicentennial the Blackbird set a World speed record of 2,193 mph.
During it’s 1990 retirement flight, it flew from Los Angeles to Washington D.C. in 67 minutes; a record for the fastest cross-country flight from coast to coast.
The SR-71 served as an unparalleled force multiplier with its advanced sensors and mission critical reconnaissance. Even with its short operational life span the SR-71 set the stage for the development of supersonic and hypersonic technology.
Many of the experiences, design practices and lessons learned from the Blackbird are still being applied today in the Air Force’s development in the hypersonic community.
The Air Force is working on the next generation of combined cycle engines to power future hypersonic vehicles from runway to hypersonic speeds and many of the problems that were overcome with the SR-71 are being used in the research. The shape, complexity and logistics of the Blackbird are directly influencing the plans for development of future semi and fully reusable hypersonic vehicles
Astronaut Neil A. Armstrong served as a NASA research pilot for the SR-71 Blackbird program before entering the space program.NASA PHOTO
Did You Know?
– The camera on the SR-71 could accurately capture the license plate of a car from 80,000 ft.
– It was named Blackbird due to its advanced stealth capabilities and heat absorbing black paint, but “Habu,” “SR,” “Lady in Black,” and “Sled” are other known nicknames.
– From the cockpit at the pilot can see the curvature of the Earth and stars during daylight while flying in the top one percent of atmosphere.
– Over 4,000 missiles have been fired at the SR-71, none of them hit.
– The SR-71’s celestial navigation system was called “R2-D2.”
– The structure of the Blackbird was designed to seal and tighten at altitude, so on the ground it “creaked” a lot and leaked fluids.
Source Material: af.mil, Lockheed Martin, NASA, Air Force Research Laboratory
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