Hey Sheik,
I have heard that about the straight 50's... Does the straight 50 have a different fuel system? You said you depart with the center tank empty? On the 50EX we have 3 "wing tanks" and 3 feeder tanks... each wing tank feeds it's respective feeder which feeds its respective engine... If we depart with the "center" tank empty, ol' #2 is just along for the ride....
Yeterday we departed from near Boston with 9,500 lbs. of fuel and 4 pax on board, climbed directly to FL430 and cruised at Mach 0.83 all the way to Chicago... Temp at altitude was ISA, time to climb to 430 was about 18 mins...
They advertise the 50EX range as 3,220 NM.... my guess is it is closer to 3,000 NM.... I have gone 7 hours and still landed with 2,800 lbs on board....