How did the F28 have such a good L/D ratio?
They just got this wrong. I have flown F28-1000 and -4000, the F100 and the B767-300. The most feet per nautical mile lost of these with idle power at any given Indicated Air Speed (say 270-280 below 25000 ft) is the F28-1000 (around 475 fpnm) then the F28-4000 at about 425 fpnm, then the F100 at about 350 fpnm and the best is the B767 at about 300-330.The 425 fpnm figure for the -4000 was measured by me around 2004 to get data for MS Flight Sim. All the rest are educated guesses.