>>1169733No. It was inefficient compared to a high-bypass turbofan, but it was efficient for the flight regime it operated in. A pure turbojet is the most efficient engine configuration for high-speed operation (in excess of Mach 1). I'll give you, it did use a lot of gas, but for sustained operation at Mach 2.0 it used that fuel efficiently. It burned a lot of gas on takeoff and acceleration when the afterburners were lit, but when the afterburners were deselected during the latter segment of the acceleration/climb, it used ram effect to provide the additional thrust necessary, allowing it to supercruise.
I don't mean to play a game of semantics, but it operated in a completely different flight regime than other airliners, and for the flight regime it certainly was efficient. It wasn't economical from a fuel burn standpoint compared to a conventional airliner, but fuel economy =/= fuel efficiency.