# What is the gas mileage on a 747?

How many feet will one gallon of fuel propel a Boeing 747?

IANA expert, but I believe airplane fuel consumption is measured in units of fuel per hour of operation, not distance covered. Flying in a tailwind vs a headwind can make a huge amount of difference in you miles per gallon

You can do the final calculation.

I’d say 0.2 MPG is damn good for a vehicle that moves 524 passengers at over 550 MPH.

Take that, Toyota Prius!

True. Also in large aircraft fuel quantity and use is measured in weight rather than volume. Volume changes with temperature, but the weight of fuel used for a given power setting remains the same. So pounds/kilograms per hour is how it’s generally measured.

That’s not to say that thinking in terms of miles per gallon is useless, just a little less accurate.

Heh, a teacher of mine (retired Air Force B-52 pilot) half-jokingly mentioned that, while on the ground, the B-52 Stratofortress has a gas mileage measured in “Gallons per foot”. It was standard practice, so he told us, to load up the bomber with it’s payload, then load it well past it’s gross takeoff weight with fuel. By the time the plane traveled from the ramp to the start of the runway, it was light enough to take off…

… at which point the plane immediately went to refuel from an airborne tanker. :smack:

He assured us that once you got the damn thing into the air, it was much more fuel-efficient, since wheels on the ground are horribly draggy compared to retracted wheels inside the airplane in the air (and let’s not even discuss fuel efficiency for a large jet plane on a treadmill… )

Oh, another random thought, I think fuel for airplanes is always measured in terms of weight. How heavy a plane is is generally held to be more important than the volume of it’s contents. If you have 20 gallons of fuel, it makes a big difference to the plane if that 20 gallons weighs 20 pounds or 200 pounds. If you have 20 pounds of fuel, the plane really doesn’t care if it’s 20 gallons or 200 gallons, as long as you contrive a way to get it inside the plane in a balanced manner.

This is why you keep seeing stretched versions of transport planes (both airliners and freighters), as they figure out that the plane isn’t carrying near it’s weight limit due to the bulkyness (rather than massiveness) of it’s cargo.

In light aircraft the fuel on board is usually measured in volume for consumption purposes, but converted to weight for the weight and balance sheet.

For example, a Shrike Commander has a 156 US gallon fuel tank, a fuel gauge calibrated in gallons, and engine performance charts that give fuel consumption in gallons per hour. Weight is only considered when filling out the load sheet.

Larger transport category aircraft measure fuel in weight for everything from the loading to the fuel consumption.

Measured as passenger-miles/gallon an automobile with four passengers gets 120 pass-mi/gal if it is getting 30 miles/gallon. A 747, which isn’t as fuel efficient as newer models, with a full load gets 110 pass-mi/gal. That’s using the numbers you cite.

But the 747 is going 550mph. I’d be THRILLED to go that fast in my car, but the onramps would be a real problem.

The landing gear certainly adds some drag, but the big problem is the inefficiency of jet engines at low airspeeds and low altitudes. The big improvement when airborne is mainly due to getting the engines into a regime for which they were designed.

And since the real-world load factors for aircraft tend to be substantially better than for cars (which apparently average less than 1.5 occupants), the fuel economy advantage lies with the airliner.

As butler1850 notes, the speed advantage is huge. Fully loaded, the car delivers around 250 passenger-miles per hour; the 747 can exceed 300,000. And 747s can (and routinely do) spend 18+ hours a day in the air, which translates to well over 5 million passenger-miles per day. Since what travelers pay for is passenger miles (with a premium for speed), it’s not surprising that Boeing has been selling 747s for nearly 40 years, and can continue to get impressive prices for them.

As I understand it, at high altitudes, a plane will sip fuel the way a supermodel guzzles a milkshake. It doesn’t take much power to keep the speed up.

Similarly, one of the quizzes in More of the Straight Dope, or whatever the second SD book is called, says that an oil tanker gets 31 feet per gallon. Or was it an aircraft carrier?

Do they pay standard fuel rates for that fuel? That is, if it takes 60,000 gallons to go from Los Angeles to Melbourne, are they paying the same \$3.00/gal (or whatever. \$2.50 lately) we are? Or do they get the fuel directly from refineries for less?

Problem? That doesn’t sound like a problem to me .

Where’s you sense of adventure anyways? Apparently it isn’t thirty feet above the road, tumbling end over end, where it should be.

Are you under the impression that jet engines run on gasoline?

I’d be happy to give it a shot, but my accountant, Mrs. Butler would go :eek: at the wrecked car, husband, and the time I’d have to take away from work!

Now where do I find a tire that could handle that speed for my '05 Subaru Baja… and should I leave the tailgate up or down during cruise?

I think it’s safe to assume that if you’re an airline using millions of gallons of jet fuel a week, you should be able to negotiate a discounted price, as compared to someone buying mere dozens of gallons. But no one is going to sell it to you below cost, so you can still expect to spend a lot of money on fuel.

After a bit of googling, it appears that jet fuel is primarily based on kerosene (which is the petroleum fraction between gasoline and diesel). The price seems to average \$4/gallon for Jet A (which seems to be the standard) fuel purchased for general aviation. Cite. The big carriers probably have deals to get it cheaper, since they probably use the overwhelming majority of it.

Also consider that kerosene will have a slightly higher energy density than gasoline. So, it seems that gasoline and jet fuel prices are somewhere in the same ballpark… probably close enough to continue the back-of-the-envelope price and efficiency calculations here.