After the Second World War, the so-called "Atomic Age" promised everything. However, the Cold War soon materialized, and the two great powers explored various ways to heat it up a bit. One of them was installing nuclear reactors in airplanes. The plan for a long-range bomber capable of dropping its lethal cargo on enemy cities was tempting, but it became obsolete in record time for several reasons, some quite obvious.
The American NEPA and ANP Programs
The United States Army Air Forces (USAAF) initiated in May 1946 (a year before its dissolution) the NEPA project, short for Nuclear Energy for the Propulsion of Aircraft. Five years later, it was absorbed into the ANP program (Aircraft Nuclear Propulsion) under the supervision of the Atomic Energy Commission and the new USAF.
The program's ultimate goal was the development and evaluation of the Convair X-6, an experimental long-range bomber equipped with a nuclear reactor and special engines that, according to the hypotheses of the time, could remain in the air for entire weeks without depending on traditional fuel.
In 1955–56, the program produced the X-39 engine from General Electric (essentially a J47 engine for nuclear operation), and the HTRE-1, the first nuclear reactor to power a turbojet engine in January 1956. Later, it had two revisions: HTRE-2 and HTRE-3.
Video on atomic airplanes:
The Convair NB-36H and Its Shielding
The only American aircraft to carry an operational nuclear reactor on board was the Convair NB-36H (initially designated XB-36H), known as the "Crusader," or simply the "Nuclear Test Aircraft." The reactor was never connected to the propulsion system or avionics, and the NB-36H's task was solely to evaluate all the parameters needed to implement nuclear flight safely, starting with shielding.
The original cabin was replaced with a lead and rubber structure weighing eleven tons, and even the smallest windows received lead glass with a minimum thickness of ten inches. The reactor had a power of one megawatt, and the total tests for the NB-36H amounted to 47, with 215 flight hours between September 1955 and March 1957—89 of them with the reactor on (but always using conventional propulsion). The aircraft was dismantled a year later, and the entire program was eventually cancelled in 1961.
The Soviet Tupolev Tu-95LAL
Needless to say, the Soviets also worked on a similar project, using the Tupolev Tu-95LAL, a derivative of the Tupolev Tu-95. During much of the 1960s, the Tupolev Tu-95LAL performed more than 40 flights, most with its reactor turned off. As with the Crusader, the priority of the Russian program was to evaluate the robustness of the shielding. Information becomes scarce here, but most sources suggest it was efficient enough to start the second phase of the program, which would have led to the development of the Tupolev Tu-119.
Why Did These Projects End?
However, the two major projects of both powers ended prematurely. On the one hand, the environmental risk was unacceptable given the possibility of an accident, and on the other, intercontinental ballistic missiles conquered the world. Once the technology based on the R-7 Semyorka put Sputnik and Yuri Gagarin into orbit, all forces understood that their resources had to be invested in that field.
(From our archives, originally published in November 2017, with some adjustments. A good choice to finish this "atomic weekend.")
Sources:Aviation History, T3VA
