5 ms·

Wouldn't flying imply a much higher energy usage then driving ? Because then weight is carried by the roads and only one directional force is needed ? And flyi

by Gys 9y ago

Wouldn't flying imply a much higher energy usage then driving ? Because then weight is carried by the roads and only one directional force is needed ? And flying being faster implies even more energy because moving slowly is generally more efficient ? Especially on shorter distances I wonder how the energy needs compare for flying vs driving.

TylerE 9y ago
Yes, however... Flying is much more SPACE efficient. With good computer control you could stack hundreds of "roads" worth of capacity vertically. Can save time (and thus indirectly energy) by flying directly from A-to-B. This is ignoring the time gained by the likely much faster cruising speeds, as well. Flying doesn't have to be THAT inefficien, either. Plenty of general aviation aircraft, especially slower ones, can achieve MPG that is really not that bad. The Mooney M20, for instance, cruises at 180mph and burns 10 gallons an hour - so 18mpg. Not bad given the speed! A car going that first will be consuming much more fuel.
- jessriedel 9y ago
  To add to your last paragraph for folks who find this surprising: If you take a airplane and let the area of the wings go to infinity while taking their wing mass and thickness to zero, the vehicle would expend arbitrarily little energy maintaining altitude; it's basically a giant, extremely slowly falling parachute. Real-world wings do not achieve this of course, but not nearly as much energy needs to be expended compared during cruise as (say) simply hovering by pointing the engine at the ground (if your engine was even powerful enough to do that).
thomastjeffery 9y ago
Ground is not flat. Going uphill requires a lot more energy. Ground has a lot more traffic. Ground traffic is not only constrained to the ground, but to roads, which, comparatively, cover a minuscule amount of area. Flight opens us up to much more than the product of ground area and height. > And flying being faster implies even more energy because moving slowly is generally more efficient? Aircraft will be less efficient at lower speeds[0]. A Cessna 182T Skylane[1] will stall at 56mph (49 knots), cruise at 167mph (145 knots). We don't need to fly faster than we drive to see significant time improvement. The distance for me between home and Provo is 51 miles, but I have to drive across 75 miles of road to get there. By taking roads, I also have to stop at intersections, and wait for traffic. If I average (with stops) 55mph, I will get there in 1hr 22min. If I flew a Skylane at 60mph (just over stall speed), I would get there in 51min. (At cruise speed, I would get there in 18min.) Obviously, I would need places to take off and land, etc. [0]https://en.wikipedia.org/wiki/Slow_flight https://en.wikipedia.org/wiki/Slow_flight [1]https://en.wikipedia.org/wiki/Cessna_182_Skylane https://en.wikipedia.org/wiki/Cessna_182_Skylane

by Gys 9y ago

TylerE 9y ago

Yes, however... Flying is much more SPACE efficient. With good computer control you could stack hundreds of "roads" worth of capacity vertically. Can save time (and thus indirectly energy) by flying directly from A-to-B. This is ignoring the time gained by the likely much faster cruising speeds, as well. Flying doesn't have to be THAT inefficien, either. Plenty of general aviation aircraft, especially slower ones, can achieve MPG that is really not that bad. The Mooney M20, for instance, cruises at 180mph and burns 10 gallons an hour - so 18mpg. Not bad given the speed! A car going that first will be consuming much more fuel.

jessriedel 9y ago
To add to your last paragraph for folks who find this surprising: If you take a airplane and let the area of the wings go to infinity while taking their wing mass and thickness to zero, the vehicle would expend arbitrarily little energy maintaining altitude; it's basically a giant, extremely slowly falling parachute. Real-world wings do not achieve this of course, but not nearly as much energy needs to be expended compared during cruise as (say) simply hovering by pointing the engine at the ground (if your engine was even powerful enough to do that).

thomastjeffery 9y ago

Ground is not flat. Going uphill requires a lot more energy. Ground has a lot more traffic. Ground traffic is not only constrained to the ground, but to roads, which, comparatively, cover a minuscule amount of area. Flight opens us up to much more than the product of ground area and height. > And flying being faster implies even more energy because moving slowly is generally more efficient? Aircraft will be less efficient at lower speeds[0]. A Cessna 182T Skylane[1] will stall at 56mph (49 knots), cruise at 167mph (145 knots). We don't need to fly faster than we drive to see significant time improvement. The distance for me between home and Provo is 51 miles, but I have to drive across 75 miles of road to get there. By taking roads, I also have to stop at intersections, and wait for traffic. If I average (with stops) 55mph, I will get there in 1hr 22min. If I flew a Skylane at 60mph (just over stall speed), I would get there in 51min. (At cruise speed, I would get there in 18min.) Obviously, I would need places to take off and land, etc. [0]https://en.wikipedia.org/wiki/Slow_flight https://en.wikipedia.org/wiki/Slow_flight [1]https://en.wikipedia.org/wiki/Cessna_182_Skylane https://en.wikipedia.org/wiki/Cessna_182_Skylane