Freighter vs. Pax Max Range
05-07-2007, 08:22 PM
#1
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Freighter vs. Pax Max Range
Simple question that probably has a simple answer.
Why is that the freighter versions of passenger aircraft have such greatly reduced range?
For example, Boeings website lists the max range for the 772LR as 9,420nm. The new 777F (based on the 772LR) is listed as having a range 4,885nm.
Both are listed as having the same MTOW of 766,000lbs. While the freighter carries about 36,000lbs less fuel than the pax model, I dont see how that would be enough to drastically reduce the range that much.
So what gives?
Why is that the freighter versions of passenger aircraft have such greatly reduced range?
For example, Boeings website lists the max range for the 772LR as 9,420nm. The new 777F (based on the 772LR) is listed as having a range 4,885nm.
Both are listed as having the same MTOW of 766,000lbs. While the freighter carries about 36,000lbs less fuel than the pax model, I dont see how that would be enough to drastically reduce the range that much.
So what gives?
05-07-2007, 08:50 PM
#2
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I don't have any experience flying civil cargo or pax but I'm pretty sure the experience I have translates. From my experience cargo generally weighs more per area or volume than passengers. It's not as pronounced in a PA-28, but large transport jet aircraft burn much more gas the heavier they are. I'd say the reduced overall fuel and the fact that the payload is much heavier lends to the reduced range.
05-07-2007, 08:57 PM
#3
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Simple question that probably has a simple answer.
Why is that the freighter versions of passenger aircraft have such greatly reduced range?
For example, Boeings website lists the max range for the 772LR as 9,420nm. The new 777F (based on the 772LR) is listed as having a range 4,885nm.
Both are listed as having the same MTOW of 766,000lbs. While the freighter carries about 36,000lbs less fuel than the pax model, I dont see how that would be enough to drastically reduce the range that much.
So what gives?
Why is that the freighter versions of passenger aircraft have such greatly reduced range?
For example, Boeings website lists the max range for the 772LR as 9,420nm. The new 777F (based on the 772LR) is listed as having a range 4,885nm.
Both are listed as having the same MTOW of 766,000lbs. While the freighter carries about 36,000lbs less fuel than the pax model, I dont see how that would be enough to drastically reduce the range that much.
So what gives?
"With a maximum takeoff weight of 766,000 pounds (347,450 kilograms), the 777 Freighter will have a revenue payload capability of 229,000 pounds ( 103.9 metric tons).
The 777 Freighter will be capable of flying 4,885 nautical miles (9,047 km) with a full payload and general cargo market densities, making it the world's longest-range freighter. "
So,
Even if you had a 777-300ER with 365 heavy people in it, say 250# each that would be 91250# plus crew and catering. Still less than 1/2 the load of the Freighter at 229K, so the pax model starts out the equation with 137.7K of extra fuel at the same max gross, how far can your airplane fly on 137K ? One might argue that the fixtures/galleys/seats weigh something, yep they do, but the cargo deck, rollers and doors etc add up too.
Bottom line, the pax model can carry a whole lot of extra gas at the same gross weight, because the payload is so much lighter, as a general rule, your milage may vary...
Have I missed anything here?
05-07-2007, 09:20 PM
#4
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From the Boeing Website:
So,
Even if you had a 777-300ER with 365 heavy people in it, say 250# each that would be 91250# plus crew and catering. Still less than 1/2 the load of the Freighter at 229K, so the pax model starts out the equation with 137.7K of extra fuel at the same max gross, how far can your airplane fly on 137K ? One might argue that the fixtures/galleys/seats weigh something, yep they do, but the cargo deck, rollers and doors etc add up too.
Bottom line, the pax model can carry a whole lot of extra gas at the same gross weight, because the payload is so much lighter, as a general rule, your milage may vary...
Have I missed anything here?
So,
Even if you had a 777-300ER with 365 heavy people in it, say 250# each that would be 91250# plus crew and catering. Still less than 1/2 the load of the Freighter at 229K, so the pax model starts out the equation with 137.7K of extra fuel at the same max gross, how far can your airplane fly on 137K ? One might argue that the fixtures/galleys/seats weigh something, yep they do, but the cargo deck, rollers and doors etc add up too.
Bottom line, the pax model can carry a whole lot of extra gas at the same gross weight, because the payload is so much lighter, as a general rule, your milage may vary...
Have I missed anything here?
05-07-2007, 09:41 PM
#5
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The math is a little bit closer, because even with fat pax the 777 has room in the belly for cargo.
With 91000# of self-loading cargo you can still cram about 50,000# in the belly. (I'm WAG-ging it here but I'm sure a 777 guy from AA, CAL, UAL or somewhere will tweak my numbers). You end up with about 87,000# more in the cargo version.
In a different job in a different time (ie before 9/11) I had a fleet manager at AA tell me that the AA 777 JFK-LHR flight would make $$ with NO pax on board - they were all gravy.
As another example of 777 fuel numbers, the typical DFW-MIA 777 (AA of course) dispatches with about 10% of the fuel tank capacity.
Bottom line - the airplane is extremely flexible. You can load it up with cargo and 10% in the tanks, or fill up the tanks and fly it for 16 hours.
With 91000# of self-loading cargo you can still cram about 50,000# in the belly. (I'm WAG-ging it here but I'm sure a 777 guy from AA, CAL, UAL or somewhere will tweak my numbers). You end up with about 87,000# more in the cargo version.
In a different job in a different time (ie before 9/11) I had a fleet manager at AA tell me that the AA 777 JFK-LHR flight would make $$ with NO pax on board - they were all gravy.
As another example of 777 fuel numbers, the typical DFW-MIA 777 (AA of course) dispatches with about 10% of the fuel tank capacity.
Bottom line - the airplane is extremely flexible. You can load it up with cargo and 10% in the tanks, or fill up the tanks and fly it for 16 hours.
05-08-2007, 06:28 AM
#7
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Bow WOW
I don't remember the EXACT figure, but I ferried a PAX MD11 to SIA for conversion, and I noticed the BOW was significantly higher (all those seats and three gallies and bluerooms).
Of course, after all this stuff is stripped out, the new upper deck cargo door, and floor beef-up adds some weight back on too.
The previous answers about the range issue are correct. With a maximum PAYLOAD, I can't take a full load of fuel. Since we want to make max $$, on the rare occasion, we'll load up the jet and make a tech stop in Japan for gas when operating HKG-ANC. Usually, we avoid any tech stops and defer loading space A freight, so it's a max weight taxi and takeoff out of China for the states or Europe.
PS. The MD will fly a LONG way with a full tank. Our first MD delivery from conversion flew non-stop from Singapore to Louisville (at least 9700 miles) 17+ hours, full fuel, no payload, no problem....
Of course, after all this stuff is stripped out, the new upper deck cargo door, and floor beef-up adds some weight back on too.
The previous answers about the range issue are correct. With a maximum PAYLOAD, I can't take a full load of fuel. Since we want to make max $$, on the rare occasion, we'll load up the jet and make a tech stop in Japan for gas when operating HKG-ANC. Usually, we avoid any tech stops and defer loading space A freight, so it's a max weight taxi and takeoff out of China for the states or Europe.
PS. The MD will fly a LONG way with a full tank. Our first MD delivery from conversion flew non-stop from Singapore to Louisville (at least 9700 miles) 17+ hours, full fuel, no payload, no problem....
Last edited by fr8rcaptain; 05-08-2007 at 06:38 AM.
05-09-2007, 03:57 PM
#9
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05-09-2007, 07:03 PM
#10
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I guess then it is safe to say that on that particular flight, there wasnt much else but fuel on board. Impressive, none the less!
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