It is the Sukhoi T-4, Su-100, or S-100 that represents the ambitious impulse of the Soviet Union to develop high-speed reconnaissance and strategic bomber aircraft during the Cold War. Running parallel with comparisons to the US XB-70 Valkyrie, the T-4 was planned to fly over Mach 3 at altitudes that would place it beyond enemy fighters and surface-to-air missiles.
At the beginning of the 1960s, the Soviet government ordered the design of a new supersonic plane that could perform reconnaissance missions and, if necessary, bomb any target. The aim was to create an aircraft whose main characteristics would not differ too much from those of the American A-12 Oxcart that had just entered service in 1963. Specifications for a Mach 3+ capable aircraft were laid down, and developed in parallel with the A-12 and XB-70. However, the Soviets were lagging in this technology, and the first flight of the T-4 was not until 1972, almost a decade after the A-12.
The T-4 represented a technological dream, the fruit of a prolonged period of research and development: “Nearly 600 patents or inventions are attributed to the program,” Construction was mainly in stainless steel and titanium. It had quadruple redundancy fly-by-wire control with a mechanical backup.
One of its most distinguishing features, the T-4 had a “droop snoot,” where the nose section could be dropped down to enhance pilot visibility for takeoff and landing. In flight, the pilots did not have any forward visibility and thus had to fly completely on instruments. A periscope was fitted that allowed some forward view below 370 mph (600 km/h).
The first flight for the T-4 was made on August 22, 1972, piloted by test pilot Vladimir Ilyushin. The aircraft went through only ten test flights and a total flying time of only 10 hours and 20 minutes. During these tests, the T-4 reached a maximum speed of Mach 1.3 at 40,000 feet.
It was shelved in mid-1974, and a year later, it axed the whole project. The axing had to do with several reasons; among them, it was the high costs that were running, the complications within the design and engineering, and the generally changing priorities within the Soviet military. The T-4 was designed to reach speeds as high as Mach 3.0, but this was never realized in a full performance of the aircraft because the program was axed.
Although the T-4 never entered service, a valuable experience and another step forward in aircraft design and technology have been gained from it. The first flying prototype of the T-4 is preserved in the Central Air Force Museum near Moscow as a token of the abilities of the engineers and the ambition of the Soviet aerospace industry.
On the whole, the Sukhoi T-4 was an exceptional aircraft able to extend many of the new frontiers in aviation technology. Though it finally did not enter operational service, the T-4 remains one of the most interesting chapters in the history of military aviation-a vivid example of the unceasing pursuit of novelty during the years of the Cold War.