Luis777 From Mexico, joined Aug 2004, 89 posts, RR: 0 Posted (8 years 4 months 6 days 8 hours ago) and read 9859 times:
I want to share some of my research about fuel consumptions of big birds, this information is not official, I've made a research of airplanes performance by reading some technical books, watching photos of readouts, talking with pilots and other aviation enthusiasts. This is only average fuel flow on cruise, and it's important to notice that this data depends of many factors, including, weight of the airplane, center of gravity, wind, temperature, flight level, engine type, use of APU, ice accumulation, use of thermal anti-ice, and even how the crew uses the FMC and a lot of things more.
If you can correct me and share more detailed information I will appreciate it a lot, thanks.
Strange, I always had the figure of approx. 12.000kg/h in my head. Your number would allow the 744 an endurance of 19.5h flight (assuming 180.000kg of kerosene are onboard), which appears to be a bit too much to me. Where exactly did you get that number from? I remember many discussions about the longest commercial flight of a 744 and 744ER, I think there was hardly a flight over 14h. Wasnt MEL-LAX one of the longest flights?
Luis777 From Mexico, joined Aug 2004, 89 posts, RR: 0
Reply 4, posted (8 years 4 months 5 days 14 hours ago) and read 9632 times:
Route: LAX-MEL G/C Distance: 6902 NM
Alternate:CBR G/C Distance: 251 NM
Mach 0.85 = 490 TAS
Average W/C = M080
Ground Speed = 490kts - 80kts = 410 kts
Flight Time LAX-MEL = 6902NM/410kts = 16.83 hrs = 16:50
Flight Time MEL-CBR = 251NM/410kts = 0.51 hrs = 00:31
5 per cent en-route time = 0.84 hrs = 00:50
Holding over Alternate Airport (1500 ft AFE) = 00:30
Total Flight Time 16:50 + 00:31 + 00:50 + 00:30 = 18:41 = 18.6833
If my average fuel flow is 9,200 kg/hr, then my minimum fuel for this trip is:
9,200 kg/hr X 18.6833 = 171,886 kg
Fuel Capacity on Boeing 747-400 (No ER) is 164,073 kg and others 174,101 kg
MTOW = 362,880 kg - 396,900 kg
OEW = 182,000 kg (variable)
a 747-400 can takeoff with MTOW at LAX, so my payload is going to be:
Payload = 396,900 kg - 182,000 kg - 171,886 kg = 43,014 kg
If the average american-australian passenger is 80 kg plus 25 kg checked baggage then final weight is 105 kg.
43,014 kg / 105 kg = 410 pax
I can make this trip with a load full of pax and zero cargo, but if my average wind component is bigger than 80 kts head I'll have to unload some pax or make a fuel stop at Nadi or somewhere else. I think that LAX-MEL is one of the longest flights made by a 747-400, that's why Qantas requested the 747-400ER with fuel tanks of 183,278 kg - 193,130 kg and MTOW = 412,770 kg.
Please notice that I still use an average fuel flow of 9,200 kg, for real life the plane will utilize more fuel for holding at 1,500 ft above alternate and the trip to CBR as is very short I think that would fly at FL280 or lower where the fuel flow is larger.
Jush From Germany, joined Apr 2005, 1636 posts, RR: 3
Reply 7, posted (8 years 3 months 3 weeks 6 days 19 hours ago) and read 9406 times:
Quoting Luis777 (Thread starter): This is only average fuel flow on cruise, and it's important to notice that this data depends of many factors, including, weight of the airplane, center of gravity, wind, temperature, flight level, engine type, use of APU, ice accumulation, use of thermal anti-ice, and even how the crew uses the FMC and a lot of things more.
I'm interested how come you get any vague figures out ouf your sources when you say it's depending on THAT many factors.
Thank you anyway i have never seen figures like that before so it is really interesting to compare plane for plane.
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