From the Planes You’ve (Probably) Never Heard Of Department of Wingspan, we bring you the Sukhoi T-4.
Before the advent of the intercontinental ballistic missile, high-altitude bombers provided the only means of delivering a large nuclear bomb to its target. But early jet bombers remained susceptible to jet interceptors, so the obvious solution was to develop a bomber that could fly higher and faster than any fighter and could reach altitudes of more than 70,000 feet at speeds above Mach 2. America’s attempt to build such a supersonic super bomber was made with the North American XB-70 Valkyrie, though it was canceled after only two were built, one of which was involved in a fatal crash. But in the heat of the Cold War arms race, the Soviet Union decided they needed their own super fast penetration bomber, and they looked to the XB-70 to build one for themselves.
This wasn’t the first time the Soviets cribbed from an American design. Towards the end of WWII, Russia reverse engineered a Boeing B-29 Superfortress that had made an emergency landing in Russia. They copied it rivet for rivet, right down to duplicating the word “Boeing” on the rudder pedals. Dubbed the Tupolev Tu-4, Russia built nearly 850 of them. While the Sukhoi T-4 (also called the T-100 or Project 100) was by no means a carbon copy of the XB-70, the influence the XB-70 had on its Soviet counterpart was clear.
Overall, the T-4 was smaller than the Valkyrie, an had a compound delta wing as compared to the true delta of the XB-70. The Tu-4 also did not employ the drooping outer wings of the Valkyrie that were used to take advantage of compression lift. The T-4 also had a single vertical stabilizer, and used a drooping nose taken from the Tu-144. During high-speed flight, the pilots used a periscope to see forward when the nose was raised. Both aircraft shared forward canards and triangular intake ramps under the fuselage, but where North American employed six engines on the massive Valkyrie, the smaller T-4 had only four. The Kolesov RD-36 turbofans, variants of those used on the Tu-144 SST (itself heavily influenced by the Anglo-French Concorde), generated 35,000 pounds of thrust each and gave the T-4 a projected top speed of Mach 3.
The T-4 presented significant technological challenges for its Soviet designers. Like the Valkyrie, the T-4 made use of titanium structures that provided both strength and lightness and could withstand the demands of Mach 3 flight. But Sukhoi had to develop new techniques to machine and weld the exotic metal, and as many as 600 patents for new manufacturing processes came out of the T-4 program. The Soviets also made advances in the realm of fly-by-wire controls, and the T-4 was one of the first Russian designs to use the system, though it also had quadruple redundancy and a mechanical backup in case the advanced system failed.
The first T-4 took its maiden flight on August 22, 1972 piloted by Vladimir Ilyushin, son of the famed Russian aircraft builder Sergei Ilyushin. Over the course of 10 test flights totaling a little more than 10 hours of total flying time, the T-4 only achieved a speed of Mach 1.3 and an altitude of 19,000 feet. As with the Valkyrie, the enormous cost of the program (the Soviet Air Force initially hoped to build a staggering 850 of them) and the advent of high-altitude antiaircraft missiles cast doubt on whether the T-4 could complete its mission. Soviet military planners also felt the need to put money into more conventional aircraft that would be of more use.
Ultimately, as with the Valkyrie, the T-4 became an anachronism, a plane whose time had come and gone before it made its maiden flight, its survivability put in doubt by modern antiaircraft missiles and its mission made redundant by ICBMs. Just two aircraft, designated 101 and 102, were built, and only 101 ever flew. Two other prototypes were left unfinished when the program was abandoned in 1974, and all but one were scrapped. The sole remaining T-4 is now on display at the Central Air Force Museum near Moscow.
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