The NR-349 was a proposed interceptor variant of the A-5 Vigilante, equipped with a third J79-GE-10 engine. However some other reports suggest that the third engine was in fact a Rocketdyne XLR46-NA-2 rocket engine for performance at high altitudes. Projected speed was Mach 2.5 and a service celling of 80,000 feet.
Official models were made, however the concept wasn’t followed by the USAF.






