Blackbird at 25: The legacy of America's ultra-fast spy plane

Our subject's story can begin with the advent of the jet engine, which elevated the race for speed to a completely new level. By the 1950s, rapid advancements in aviation and missile technology (including anti-aircraft missiles) necessitated new solutions. These weren't just to deliver a nuclear bomb to enemy territories effectively but also to identify optimal targets beforehand.

The Americans initially attempted to fly at altitudes supposedly too high for Soviet air defenses to intercept their U-2 reconnaissance aircraft (which remains interesting and still in service).

In 1960, this belief was shattered when the Soviet S-75 anti-aircraft system successfully shot down one of these aircraft (piloted by F. G. Powers). Thus, a different approach was adopted: speed. To minimize flight time over hostile areas and ensure the safety of increasingly expensive machines and their pilots, extreme speed became the focus. One of the most successful outcomes of this concept was the SR-71A Blackbird.

The SR-71A is directly descended from or can actually be considered a developmental version of the Lockheed A-12 aircraft. The Lockheed A-12 was a superfast (reaching speeds over Mach 3, or 2,237 mph) and high-altitude (flights above 85,000 feet) reconnaissance aircraft.

Development for the CIA began in 1959, and in a sense, it continued for a long time, even though the A-12's active service was short-lived. Test and combat flights were conducted only between 1962 and 1968; the aircraft was decommissioned as improvements in satellite-quality data were made. During this time, a two-seater training version was designed, and the USAF developed the YF-12, a fast fighter project. The M-21 aircraft was also developed for the USAF-CIA partnership as a carrier for the fast (Mach 3.3, over 2,485 mph) D-21 reconnaissance drone. All these programs were eventually closed, influenced by accidents (some fatal).

The SR-71A began development in 1960, with its prototype initially intended as the reconnaissance-bomber version, YF-12, called RS-12. Over time, its strike function was abandoned, and the reconnaissance variant entered service in 1966, incorporating many significant changes.

The SR-71A was slightly larger than its predecessor, featuring a longer nose section and enlarged fuel tanks (80,235 pounds, plus the capability to refuel mid-air). The electrical system was also updated; most importantly, new equipment was introduced. The AINS astro-inertial navigation system, initially developed for AGM-48 Skybolt missiles, was implemented. New onboard and external communication systems were also added.

The Blackbird's value lies primarily in its reconnaissance capabilities and outstanding performance. It was outfitted with a GA-531 SLAR side-looking radar system and an ERS passive electronic reconnaissance system. The ERS system allowed detections up to 311 miles on either side of the aircraft. Upon detection, the system automatically tuned to the emission, tracked it, and recorded the data on cassette tape (up to 30 minutes).

The Fairchild F489 camera with a wide-angle lens for terrain mapping could be optionally installed in one compartment. Its film, 662 feet long, allowed for photographing a 9-mile-long strip. This data was used to record objects detected through other means and to provide exact locations.

Other compartments could house, among other things, two high-resolution panoramic cameras, Hycon HR-308B (1,800 frames over a route up to 2,302 miles, with each "photo" covering about 2.5 square miles). While these cameras had lenses placed obliquely, the Itek HR-9085 operated with a mirror system. The equipment could also include two HRB-454 infrared scanners (mounted obliquely).

Over time, newer equipment, such as the new OBC panoramic camera (using ISO 8 sensitivity film), appeared to replace the nose SLAR radar (eventually supplanted by the CAPRE radar and later the higher-performing ASARS). This sophisticated equipment complemented satellite data and other forms of intelligence gathering.

But the SR-71A's real fame came from its breathtaking speed. Its cruising speed reached Mach 3.2 (2,485 mph) at an altitude of 79,000 feet, with a maximum likely higher (rumors suggest even more than Mach 3.3, which at this altitude would exceed 2,485 mph), making it faster than the Soviet high-speed fighter MiG-25.

To withstand such speed without disintegrating, 85 percent of the aircraft's structure was made from titanium (interestingly, mostly imported from the Soviet Union). The aircraft's skin panels were slightly corrugated, making them more resilient and less prone to cracking. High speed creates significant friction, leading to high temperatures (e.g., the cockpit windshield heated up to 600 °F). To compensate for the thermal expansion during flight, the aircraft's elements fit loosely, sealing properly only when airborne. Some reports suggest that even the fuel system leaked when the aircraft was "cold," but this seems more of an urban legend than fact.

Efforts were made to reduce radar visibility, a modest achievement for such a large aircraft (55-foot wingspan, 107-foot length, 19-foot height, empty weight 67,460 pounds) with a radar cross-section of 10 square meters. The JP-7 fuel was also enriched to minimize exhaust visibility. The J58-1 engines provided thrusts of up to 151 kN (version JT11D-20J), and adjustable air intakes ensured each engine's proper function.

The crew had to wear specialist suits, which resembled space suits more than aviation suits. Such a complex and advanced machine came at a cost. Each of the 32 SR-71As built cost American taxpayers about $23 million, which today would be over $220 million per unit. Operational costs were also high: in 1990, one flight hour cost $200,000. Versions B (training) and C (alternative training) were also developed. The aircraft set several speed records, especially for average speeds.

The USAF used the Blackbird from 1966 to 1990, with the 9th Strategic Reconnaissance Wing based in California as the main operator. The aircraft primarily operated over the USSR (though it also flew over regions like the Middle East, particularly during the Yom Kippur War in 1973). There were even flights over Poland (e.g., in December 1980).

In 1989, the aircraft fell victim to the end of the Cold War, with withdrawal finalized the following year. Factors contributing to its retirement included high operating costs, advancements in alternative reconnaissance methods, and outdated communication systems. The aircraft briefly returned to service with the 9th Reconnaissance Wing from 1995 to 1997, mainly for missions over Serbia. The USAF eventually retired the machine due to costs, while NASA operated a pair of aircraft for testing from 1990 to 1998.

During its service life, 12 aircraft and one crew member were lost in accidents. Notably, the Blackbird's high speed allowed it to evade Soviet missiles and fighters, a claim that cannot be made about the newer light stealth bomber F-117.