1958: False Starts For Aviation’s ‘Atomic Age’


Aviation Week has been reporting on and, in one case unwittingly, furthering the cause of nuclear-powered aircraft for more than 60 years. Spurred on by the promise of the ‘Atomic Age’ and the potential strategic benefits of limitless range and endurance, the U.S. Air Force launched the Nuclear Energy for the Propulsion of Aircraft (NEPA) project in 1946. This was succeeded by the Aircraft Nuclear Propulsion (ANP) in 1951 which was supposed to pave the way for a strategic missile carrier that would remain on continuous airborne alert for a week or more.

The idea was to develop a hybrid propulsion system combining turbojet engines with a reactor. ANP looked at two designs: General Electric’s “direct cycle,” in which the engine airflow cooled the reactor; and Pratt & Whitney’s “indirect cycle,” in which a liquid-metal coolant carried heat from the reactor to the engine.  Ground tests of a modified J47 turbojet (dubbed X-39/HTRE-1) were conducted in 1956, although flight tests on the proposed Convair X-6 (a modified B-36) were cancelled when the project was axed in 1958.

One B-36 was, however, modified under the ANP project to carry a reactor and flew successfully 47 times between September 1955 and March 1957. Dubbed the NB-36H, the purpose of the test was to evaluate techniques for shielding the crew and systems from radiation. The Aircraft Shield Test Reactor (ASTR) was operational but provided no power to the aircraft or engines. Weighing 35,000 lb., the reactor was carried in the No. 4 bomb bay and was principally cooled by water which dissipated energy to the atmosphere through a water-to-air heat exchanger.  

The crew was protected in a purpose-made nose section which incorporated a 12-ton lead and rubber shielded compartment. Various reports indicate the cockpit windows were between 6-inches to one foot thick, while the crew used a closed circuit TV to monitor the reactor. In addition, water jackets were installed between the crew and the reactor along with a four-ton lead disc shield amidships.

The NB-36H clocked up 215 hours of flight time, 89 hours of which were with the reactor active. The aircraft was escorted on each flight by a C-97 which carried a platoon of Marines who were ready to parachute down to surround and protect the aircraft if it crashed.

Aviation Week itself caused a stir in the nuclear propulsion field when it reported in its Dec 1, 1958, edition on flight tests of what appeared to be a Soviet nuclear-powered aircraft. The report, on what later emerged to be an elaborate hoax, led to concerns that the U.S.S.R was pulling ahead of the U.S. and helped to extend funding in nuclear aircraft research for a few more years. The feature also contained a very detailed timeline of associated nuclear aircraft plans in the U.S. and foreshadowed actual flights of a modified Tupolev Tu-95 equipped with a reactor in the early 1960s. The Soviet research in nuclear-powered aircraft, like that in the U.S., effectively ended within a few years as ICBM’s rendered the concept obsolete.

Soviets Flight Testing Nuclear Bomber, December 1, 1958 Aviation Week & Space Technology

The final death knell for the U.S. program was sounded in 1961 by President John F. Kennedy who ended the ANP by stating "15 years and about $1 billion have been devoted to the attempted development of a nuclear-powered aircraft; but the possibility of achieving a militarily useful aircraft in the foreseeable future is still very remote."

While several lower-level research efforts into nuclear-powered missiles and UAVs have been made right up to the 2000s, none have made it beyond the early experimental or concept stage. The bottom line for all these projects has been that, despite vast improvements in reactor technology, fission-based nuclear propulsion cycles remain heavy, complex and inefficient. The question now is, with the possible dawn of a viable, modular fusion capability, is the new atomic age for aviation finally on the horizon?

► Read the report in the December 1, 1958 issue of Aviation Week & Space Technology:

Soviets Flight Testing Nuclear Bomber

Aviation Week is approaching its 100th anniversary in 2016. In a series of blogs, our editors highlight editorial content from the magazine's long and rich history, including viewpoints from the industry's most iconic names and stories that have helped change the shape of the industry.

Discuss this Blog Entry 9

on Oct 15, 2014

Good read!

While it's an interesting engineering challenge, it's one of those "solutions looking for a problem".

Before the days of unmanned systems, an aircraft flying around for weeks at a time was not a very realistic one. If the plane's purpose was to launch nukes at an enemy, this would be better, more efficiently, more stealthily, and cheaper to do by submarine. If the plane's purpose was launching conventional weapons, the operational costs per bomb dropped would be insanely prohibitive. And you'd still have to return to base to re-arm. Not to mention that the plane, no matter how stealthy, would eventually be located, tracked and targeted for destruction as it orbited for weeks around an unfriendly country. There would be no chance of maintaining the element of surprise. Subs do it better.

The X-37B just showed us that you could have an unmanned, orbital bomber on station for years at a time if you really wanted to - and no need for nuclear power plants.

But there's really no practical use for a long endurance bomber. All that loitering just gives the enemy all the time in the world to prepare to destroy the target.

on Dec 17, 2014

True, an offensive weapon may not be practical or cost efficient, but a nuclear (fission) powered UAV with solid state laser for defensive purposes (alla ABL) may perhaps be a better use of this future technology.

on Oct 16, 2014

I'd like to hear more about how the Soviet nuclear bomber story turned out to be "an elaborate hoax" -- by whom, to what end and how was this hoax discovered?

on Oct 16, 2014

A former editor who was at the magazine at the time told me it was a planted story designed to embarrass the magazine--perhaps because if its reputation for uncovering "secrets." He was glad he was on assignment in Europe at the time when it all hit the fan.

It was obviously the conventionally powered Bounder bomber (unknown then in the West) that someone convinced the editors was nuclear powered.

on Oct 16, 2014

This is the kind of experience and concurred engineering challenges needed to go into space in a big way. We need to rise to the challenge so some of our grandsons can be starship captains Lord let us live that long.

on Oct 17, 2014

This story concludes that no fission-powered aircraft surpassed "the early experimental or concept stage" because "fission-based nuclear propulsion cycles remain heavy, complex and inefficient" -- then speculates on a "new atomic age for aviation" from "the possible dawn of a viable, modular fusion capability."

Do you really not see the déjà vu? 1946's "new dawn" was limitless fission power; its practicalities were more sobering. The new research reported here is again in "the early experimental or concept stage," and far from showing if plasma fusion power can ever manage its notorious, _inherent_ problems (neutron damage, stable control of slippery plasmas during vast energy release) without the real-world system again being "heavy, complex and inefficient."

on Oct 17, 2014

I want one from Walmart for Xmas !

on Oct 17, 2014

I read somewhere that the NB-36 had so much shielding that it was like flying a glider: total silence in the cockpit.

on Oct 18, 2014

If Lockheed Martin's Compact Fusion Reactor (CFR) is feasible, then we might have nuclear powered aircraft after all.

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