Between 1955 and 1957, a B-36 bomber the size of a building flew over Texas and New Mexico with a live nuclear reactor humming in its belly. It was escorted everywhere by a planeload of armed Marines, ready to parachute down and seal off the area if it ever crashed.

The Convair NB-36H “Crusader” was America’s boldest, strangest Cold War experiment: an attempt to find out whether an aircraft could one day be powered by atomic energy and stay aloft for weeks. The reactor it carried never actually drove the propellers — but it proved the U.S. was deadly serious about nuclear flight.

A Reactor With Wings

The dream was intoxicating: an engine that never runs out of fuel. A nuclear-powered bomber could, in theory, loiter near an enemy for days. To test the idea, Convair gutted a B-36 damaged by a tornado and rebuilt the nose as a 12-tonne shielded crew capsule of lead and leaded glass. Behind the crew sat the reactor, lowered into the bomb bay for each flight and removed afterward.

Why It Never Powered the Plane

The NB-36H’s reactor generated heat and radiation, but it was never connected to the engines. The point was to learn whether a crew could be shielded from an airborne reactor and whether the aircraft could be operated safely. The answers were sobering: the shielding needed was enormously heavy, and a crash could scatter radioactive material across the landscape — which is why those Marines flew along on every mission.

The Soviets ran their own parallel experiment, the Tu-95LAL, with the same conclusion. Both superpowers eventually accepted that the weight and danger made nuclear-powered flight impractical, and the dream — along with the Convair X-6 that was meant to follow — was abandoned.

The documentary above explains just how far both superpowers went chasing the atomic airplane.

Sources: National Museum of the U.S. Air Force; Convair/General Dynamics records; Real Engineering.