This is a very old and well-debunked topic. There is a video available showing Leslie Robertson saying they never factored the fuel in their calculations.
http://www.abovetopsecret.com/forum/thread569606/pg12
Boeing 707 - Empty weight 55,600 Kg, passengers weight 8,250 Kg, fuel weight (assumed) 1000 Kg. TOTAL weight 65,850 Kg. Speed 180 mph or 88.6 m/sec. Kinetic Energy = 0.5 x 65,850 x 88.6 x 88.6 =
255 Megajoules.
Boeing 767 200LR - Empty weight 82,380 Kg, passengers weight 4,875 Kg, fuel weight 34,000 Kg. TOTAL weight 121,255 Kg. Speed 510 mph or 245 m/sec. Kinetic Energy = 0.5 x 121,255 x 245 x 245 =
3,640 Megajoules.
3,640 divided by 255 gives you
FOURTEEN POINT THREE TIMES.
'look' - 'internet' - 'read' - 'think' - 'apologize'.