Peter,

I have to laugh at the fuel economy when compared to a B-727. The 727 burns something like 8,500 lb. per hour. At 500 mph, it will take 5 hours to go 2,500 miles and it will burn about 42,500 lb. of fuel to do it. This is a bit of a stretch for the 727. It would have to have a very light passenger load to make this distance.

The SR-71, will also travel about 2,500 miles on fuel. At 2100 mph, it will cover this distance in a little more than 1 hour. However, to go this fast, it will consume nearly 100,000 lb. of fuel! This is what you need when you are running full afterburners to overcome the massive friction created by a speed of 2100 mph.

The Concorde is another good example. The aircraft weight is just about 400,000 lb. on takeoff from London. It lands at JFK at a weight of less than 200,000 lb. It consumed 200,000 lb. of fuel in about 3 1/2 hours. Same deal. Run four big engines at 1400 mph and watch the fuel gauge drop!

Compare the Concorde to a B-747 which will take seven hours to go from London to JFK. It consumes about 30,000 lb. per hour and burns just about the same amount of fuel as the Concorde to go the same distance. However, the B-747 weight is more than double (840,000 lb.) that of the Concorde.

The government would be thrilled if they could get the SR-71 to sip fuel like a B-727