The General Electric X211 (J87), comprising two gas turbine engines coupled to a single reactor source, was developed in the company's Aircraft Nuclear Propulsion department at Evendale under the direction of Bruno Bruckmann, who had been a senior executive with BMW in Germany during the war.

The X211 compared with the J79, engine of the F-4 Phantom.

One of the several NX-2 designs studied by Convair for the USAF's continuous airborne alert, missile-launching aircraft, featuring direct air cycle nuclear engines in the fuselage and conventional turbojets under the wings.