747-400, is it really that inefficient?

[scandinavian13 5,192]

What was the point of that post, to disprove me? NASA states that thrust to weight ratio's can be used to calculate efficiency, so, the 777 is more efficient, assuming both have the same proportional weight, same route, same wind, same cost index, same proportional passengers, same proportional everything, the 777 is .034 more efficient. Maybe I'm wrong, but if I am your going to have to prove it by replying with something that shows me otherwise.

Yes, it was to disprove you.It can be used, but it isn't the only factor, as you claim. Can you post your NASA source? I doubt it makes the same assertion you do. T/W Ratio does not consider fuel burned to create said thrust. Fuel being generally the biggest more expensive part of the equation, leaving it out of the equation is severely negligent in the efficiency claim.I'll get back to you with better math, but again, a 747 half full with a T/W ratio of .27, and an F22 with a T/W ratio of 2ish, is the F22 more efficient? No. Given that, is the onus of proof really on me, or you? Anyone else want to give their opinion on who needs to be proving their assertion?And the quote was from The Right Stuff, yes.

[captainklm 1]

What was the point of that post, to disprove me? NASA states that thrust to weight ratio's can be used to calculate efficiency, so, the 777 is more efficient, assuming both have the same proportional weight, same route, same wind, same cost index, same proportional passengers, same proportional everything, the 777 is .034 more efficient. Maybe I'm wrong, but if I am your going to have to prove it by replying with something that shows me otherwise.

But the point of efficiency is the amount of fuel used. Thrust is good but it depends on how much fuel is used

[lovetofly28 0]

Yes, it was to disprove you.It can be used, but it isn't the only factor, as you claim. Can you post your NASA source? I doubt it makes the same assertion you do. T/W Ratio does not consider fuel burned to create said thrust. Fuel being generally the biggest more expensive part of the equation, leaving it out of the equation is severely negligent in the efficiency claim.I'll get back to you with better math, but again, a 747 half full with a T/W ratio of .27, and an F22 with a T/W ratio of 2ish, is the F22 more efficient? No. Given that, is the onus of proof really on me, or you? Anyone else want to give their opinion on who needs to be proving their assertion?And the quote was from The Right Stuff, yes.

But the point of efficiency is the amount of fuel used. Thrust is good but it depends on how much fuel is used

Lets say we were to put a B744, T7, and a F22 on a runway. They all took off at the same time, with the same proportional everything, and headed to a waypoint 100 miles away. They flew the same altitude, same everything, which would have been the most efficient? Well, its whichever burned the least amount of fuel. So, how do we calculate this? Well, (Here is) yet another way to calculate efficency, which still shows the T7 as more efficient, whats your source?

[Paul_Smith 92]

Lets say we were to put a B744, T7, and a F22 on a runway. They all took off at the same time, with the same proportional everything, and headed to a waypoint 100 miles away. They flew the same altitude, same everything, which would have been the most efficient? Well, its whichever burned the least amount of fuel. So, how do we calculate this? Well, (Here is) yet another way to calculate efficency, which still shows the T7 as more efficient, whats your source?

No! Sorry but you are completly wrong about this. The F22 would have burned the least fuel, but it would have carried the least payload. If you want to measure fuel efficiency, as opposed to fuel consumption, then you need to compare how much fuel is required to transport a given payload from one point to another. In your example, if the payload was the pilot only, and the route was two airports 100 miles apart, then the F22 would be far more fuel efficient then the others. If the payload was 300 passengers over 3000 miles, then the 777 would be the most fuel efficient. Increase the payload to 500 passengers, and the 777 will have to fly the route 3 times to the 747's single trip, making the 747 the most fuel efficient FOR THAT TRIP. The site you list shows something very specific but it is only useful for choseing which engine to fit to a plane or to measure the cost impact associated with using a different type of fuel (Low freezing point etc)

[captainklm 1]

No! Sorry but you are completly wrong about this. The F22 would have burned the least fuel, but it would have carried the least payload. If you want to measure fuel efficiency, as opposed to fuel consumption, then you need to compare how much fuel is required to transport a given payload from one point to another. In your example, if the payload was the pilot only, and the route was two airports 100 miles apart, then the F22 would be far more fuel efficient then the others. If the payload was 300 passengers over 3000 miles, then the 777 would be the most fuel efficient. Increase the payload to 500 passengers, and the 777 will have to fly the route 3 times to the 747's single trip, making the 747 the most fuel efficient FOR THAT TRIP. The site you list shows something very specific but it is only useful for choseing which engine to fit to a plane or to measure the cost impact associated with using a different type of fuel (Low freezing point etc)

exactly! The a380 burns more fuel per mile but has a very low per passenger mile.

[lovetofly28 0]

No! Sorry but you are completly wrong about this. The F22 would have burned the least fuel, but it would have carried the least payload. If you want to measure fuel efficiency, as opposed to fuel consumption, then you need to compare how much fuel is required to transport a given payload from one point to another. In your example, if the payload was the pilot only, and the route was two airports 100 miles apart, then the F22 would be far more fuel efficient then the others. If the payload was 300 passengers over 3000 miles, then the 777 would be the most fuel efficient. Increase the payload to 500 passengers, and the 777 will have to fly the route 3 times to the 747's single trip, making the 747 the most fuel efficient FOR THAT TRIP. The site you list shows something very specific but it is only useful for choseing which engine to fit to a plane or to measure the cost impact associated with using a different type of fuel (Low freezing point etc)

I'm gonna go ahead and stop this conversation, just by saying that the F-22's fuel consumption's rate is far that of the T7, but I honestly dont care, I just got into this conversation to see if I could help, but whatever, we all learn differently. So who else saw the update for the NGX?

[captainklm 1]

Well we can be certain corsairs 747s are more efficient than a 777. 560 seats beats 350 seats!

[Paul_Smith 92]

Well we can be certain corsairs 747s are more efficient than a 777. 560 seats beats 350 seats!

No it doesn't. It only beats it if you have more then 350 passengers. I keep trying to tell you, the answer is not YES or NO, it is "It depends"

[captainklm 1]

every flights have their ups and downs

No it doesn't. It only beats it if you have more then 350 passengers. I keep trying to tell you, the answer is not YES or NO, it is "It depends"

Most of corsairs flights are full so it's way over 350.

[captainklm 1]

old topic but does anyone have any "exact" figures for the fuel burn?

[pcubine 143]

old topic but does anyone have any "exact" figures for the fuel burn?

Stop beating a dead horse Barton. Give it a rest, huh?Michael Cubine

[captainklm 1]

better than beating a live horse

[captainklm 1]

better than beating a live horse

[michal 44]

old topic but does anyone have any "exact" figures for the fuel burn?

Pretty detailed performance numbers for all models are available (surprise!) on Boeing website, I think finding it and flipping through the data is something that a 13- year old with a knack for aviation should be able to handle. it is not rocket science. :(

[captainklm 1]

Pretty detailed performance numbers for all models are available (surprise!) on Boeing website, I think finding it and flipping through the data is something that a 13- year old with a knack for aviation should be able to handle. it is not rocket science. :(

wow, thanks. However I can`t seem to find it. Is it in a PDF or on the website`s commercial airplane bit. Im so sorry to ask but do you happen to have a link?