Peter,

The SR-71 engines were specially designed turbojet engines to produce massive amounts thrust without any regard to fuel consumption. That aircraft has many specifications that are downright amazing. I believe that it holds the speed record for cross-country flight with a time of something like 80 minutes or so.
When it is cruising along at 2100 mph it has a turn radius of 150 miles! After a run of 80 minutes at full speed, it's just about out of fuel!

My previous discussions were regarding the more conventional large turbofans such as the GE CF6 or the Pratt and Whitney PW4000 engines.