> if I remember correctly, because its jet engines were hugely inefficient at low speeds Yes, turbojet vs turbofan. Turbojet only become efficient over Mach 1.

> if I remember correctly, because its jet engines were hugely inefficient at low speeds Yes, turbojet vs turbofan. Turbojet only become efficient over Mach 1. > the Concorde was the worst offender No, I the SR 71 was worse, it literally leaked fuel: "Similarly, the fuselage panels were manufactured to fit only loosely on the ground. Proper alignment was achieved only when the airframe heated up and expanded several inches. Because of this, and the lack of a fuel sealing system that could handle the thermal expansion of the airframe at extreme temperatures, the aircraft would leak JP-7 jet fuel on the runway." http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird