Setting aside its declared political purpose, the Tu-95N bomber—the USSR's only way of delivering the Tsar Bomb—was not a practical delivery platform: NATO fighters would shoot the lumbering plane out of the sky long before it had a chance to drop its huge bomb. You can count on one hand the number of targets in Europe big enough to merit the Tsar Bomb's attentions. One Tsar Bomb alone could burn down West Germany—if it could get there.
On July 10, 1961 Soviet Premier Nikita Khrushchev summoned the USSR's top nuclear weaponeers and told them to promptly resume nuclear testing. After roughing up America's young new President Kennedy at a Vienna summit in June, Khrushchev was in a mood, according to Andrei Sakharov, to “show the imperialists what we can do.”
(This first appeared several years ago.)
For two years while their country joined the United States and the United Kingdom in a voluntary moratorium on nuclear tests, Soviet nuclear scientists, including Andrei Sakharov, the “father of the Soviet hydrogen bomb,” developed and refined new weapon concepts and designs. Now they had to deliver big results in very short order. Khrushchev wanted a political spectacle to shock and awe the West, and it had better go right.
The Communist Party's 22nd Congress in October 1961 required something special. It isn't clear who proposed a 100-megaton bomb—Khrushchev or the weaponeers—but at the premier's command the most powerful nuclear weapon ever built had to be ready in only four months .
Such a huge bomb came about only because Soviet scientists had a good idea about how to proceed. As Carey Sublette of the Nuclear Weapons Archive website explains, “It is safe to assume that the 100 Mt bomb was a very conservative design - one that pushed no technical envelopes save for size. The two principal reasons for thinking this are the extremely compressed development schedule, and the very high profile of the test.”
High-profile indeed. Khrushchev's next move came on August 13, 1961, when East Germany began erecting the Berlin Wall. On August 31 the Premier announced the giant new bomb and the abrupt end to the USSR's voluntary moratorium; a Soviet atmospheric nuclear test followed the day after. The US responded in kind within the month.
With the Cold War escalating no time was spared. Andrei Sakharov's team at Arzamas-16, the "USSR's Los Alamos," skipped the careful mathematical analysis require for H-bomb design and worked out "Big Ivan" on the fly using approximations. At the time the largest device the Soviets had tested yielded much lower, so to achieve 100 megatons Sakharov's team used clustering and staging.
By ganging together eight or more smaller H-bombs and mating them to clusters of thermonuclear fuel capsules, a really big bomb could be built without any new technology. The resulting weapon was enormous, an unsophisticated kludge but a robust one. It had to be—failure was not an option.
Multi-megaton thermonuclear weapons rely on staging. A first-stage fission device generates the heat, pressure and radiation to ignite nuclear fusion in a second-stage fuel vessel, and the more fusion fuel, the bigger the reaction. A third stage can be added by cladding the second stage in weapons-grade uranium metal—the fusion reaction induces nuclear fission in the uranium cladding and adds many megatons of yield. All-up three-stage thermonuclear weapons can be very dirty bombs, with more than half their power coming from fission—resulting in vast amounts of fallout.
The gigantic weapon—over 26 feet long, nearly seven feet in diameter and 27 tons mass—was designed, engineered and fabricated all at once. Assembly and component testing took place inside a workshop constructed over a railroad flatcar. When it was ready a locomotive towed it to the airfield for loading into a specially-modified Tupolev Tu-95N "Bear A" bomber.
Painted a special white reflective white to reduce flash damage from the explosion, the big Tu-95N turboprop bomber was still too small to carry Big Ivan internally. Its bomb bay doors were removed and sections of fuselage cut away to mount the bomb halfway inside the plane, like a giant engorged remora.
For the delivery aircraft to get away from the blast safely the bomb's fall had to be slowed; slowing a boxcar-sized object full of uranium and steel from aviation speeds required a parachute of imperial scale. Big Ivan's drag chute consumed most of the USSR's nylon output for 1961, leaving New Soviet Women to grumble about hosiery as one more thing the workers' paradise lacked.
On October 30, 1961, under the watchful but distant eyes of State Commission Chairman Major General Nikolai Pavlov and a host of dignitaries 600 miles away, the pregnant-looking white Tu-95N and an Tu-16 airborne lab plowed their way towards Novaya Zemlya, a large icebound island in the Arctic Ocean.