Comment by willyt

Supposedly Concorde used more fuel taxiing from the stand to line up on the runway than a 737 flying London-Paris, but the fuel consumption PPM was comparable with a 747 once the plane was at super cruise. The problem is an building an engine that is efficient throughout the entire flight envelope. Engine efficiency improvements have come from gradually increasing the bypass ratio while solving some tricky problems with the tips of the blades approaching supersonic speeds, but, as I understand it, you can't use high bypass engines at supersonic speeds, so it will be interesting to see what technological advancements Rolls Royce have made over the original Olympus engines that powered the Concorde.