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In the long run, would it be cheaper to build cargo planes that can refuel in midair? That way you don’t overburdened the ground airport system. And eventuall

In the long run, would it be cheaper to build cargo planes that can refuel in midair? That way you don’t overburdened the ground airport system. And eventually, the refueling airplane can become robotic, and fly fully automated also.

quink 6y ago
Cargo can accept an hour or five refuelling in Anchorage or be half a day late. And cargo planes fly far fewer hours each day than passenger planes, leading to fewer movements per plane. OTOH the fact that the MD-10/MD-11 has a second life in cargo also is evidence that fuel burn isn’t the primary concern. And that’s cheaper than ever now, while being the primary operational cost. And weight (and thus fuel burn) is only one constraint, the other is volume. Anyway, this whole thing goes away by just adding a runway in Anchorage at most assuming anything like current demand. And especially after the still unresolved 737MAX saga there is very little appetite in commercial aviation towards increased aviation. We’re down to two people, that’s enough.
ethagknight 6y ago
Fun idea to think about. FedEx (and many others) refuels at Ted Stevens Anchorage Airport, and it looks like they have 8 refueling pads. Obviously thats a primary function of Ted Stevens and the reason why it has 3 long runways. I dont know how long the refueling stopover is, but the delay cost cant be that bad compared to an efficient, ground-based refueling operation. Then there are other challenges, like a KC-46 (the latest 767 based tanker), can only carry enough fuel to for 3 747-Fs, (or 6 half-fills). Speculating, but these jumbo jets also create so much downdraft causing a trailing plane to fall into an aerodynamic "hole," so that they need a lot of space between planes. The KC-46 costs about $150mm (flyaway cost), plus you have pilot crews, ground crews, etc to maintain them. A robotic system isn't going to look too terribly different, getting a gigantic auxiliary fuel tank up into the air. But hey, solve those problems, you might have something!
- totallyabstract 6y ago
  You'd need two KC-46 to fully refuel a 747-400F. KC-46 holds about 120KL of fuel, the 747 takes about 200KL.
philwelch 6y ago
No. In-air refueling is very much a, "now you have two problems" type of solution. The tanker bird is itself an airplane that needs to land and take off, and refuel from the ground airport system. Also, if you can make the tanker bird a UAV, you can do the exact same with the original cargo plane anyway.
- samatman 6y ago
  While I fully agree with the first paragraph, I question the second. The risk to humans in automated flight is mainly in takeoff and landing. I can readily imagine making safe UAV tanker drones which take off and land on airstrips far from human habitation, such that the occasional mistake, while expensive, costs no human life. What I can't imagine is the economics of this ever working out.
  - philwelch 6y ago
    The safety issue would also apply for mid-air refueling; that’s a precision maneuver that would endanger the crew of the cargo plane. Plus, if the cargo itself is expendable you’d be just as safe handling the cargo planes the same way as you suggest handling the fuel drones.
- peckrob 6y ago
  More to the point, there's no need because we're already very close to hitting the theoretical maximum flight distance - the point at which you could connect any airport to any other airport - which is slightly less than 13,000 miles [0]. Call it about 12,300. The A-350ULR has a range of a bit more than 11,000 miles [1]. Basically, probably some time in the next decade or so we will break through that barrier and be able to connect any two airports on Earth nonstop if we wanted to. Whether it is economical to do so is another question. [0] http://www.gcmap.com/mapui?DU=mi&P=AGP-AKL http://www.gcmap.com/mapui?DU=mi&P=AGP-AKL [1] https://www.flightglobal.com/a350-900ulr-range-figure-not-a-revision-airbus/123978.article https://www.flightglobal.com/a350-900ulr-range-figure-not-a-...

quink 6y ago

Cargo can accept an hour or five refuelling in Anchorage or be half a day late. And cargo planes fly far fewer hours each day than passenger planes, leading to fewer movements per plane. OTOH the fact that the MD-10/MD-11 has a second life in cargo also is evidence that fuel burn isn’t the primary concern. And that’s cheaper than ever now, while being the primary operational cost. And weight (and thus fuel burn) is only one constraint, the other is volume. Anyway, this whole thing goes away by just adding a runway in Anchorage at most assuming anything like current demand. And especially after the still unresolved 737MAX saga there is very little appetite in commercial aviation towards increased aviation. We’re down to two people, that’s enough.

ethagknight 6y ago

Fun idea to think about. FedEx (and many others) refuels at Ted Stevens Anchorage Airport, and it looks like they have 8 refueling pads. Obviously thats a primary function of Ted Stevens and the reason why it has 3 long runways. I dont know how long the refueling stopover is, but the delay cost cant be that bad compared to an efficient, ground-based refueling operation. Then there are other challenges, like a KC-46 (the latest 767 based tanker), can only carry enough fuel to for 3 747-Fs, (or 6 half-fills). Speculating, but these jumbo jets also create so much downdraft causing a trailing plane to fall into an aerodynamic "hole," so that they need a lot of space between planes. The KC-46 costs about $150mm (flyaway cost), plus you have pilot crews, ground crews, etc to maintain them. A robotic system isn't going to look too terribly different, getting a gigantic auxiliary fuel tank up into the air. But hey, solve those problems, you might have something!

totallyabstract 6y ago
You'd need two KC-46 to fully refuel a 747-400F. KC-46 holds about 120KL of fuel, the 747 takes about 200KL.

philwelch 6y ago

No. In-air refueling is very much a, "now you have two problems" type of solution. The tanker bird is itself an airplane that needs to land and take off, and refuel from the ground airport system. Also, if you can make the tanker bird a UAV, you can do the exact same with the original cargo plane anyway.

samatman 6y ago
While I fully agree with the first paragraph, I question the second. The risk to humans in automated flight is mainly in takeoff and landing. I can readily imagine making safe UAV tanker drones which take off and land on airstrips far from human habitation, such that the occasional mistake, while expensive, costs no human life. What I can't imagine is the economics of this ever working out.
- philwelch 6y ago
  The safety issue would also apply for mid-air refueling; that’s a precision maneuver that would endanger the crew of the cargo plane. Plus, if the cargo itself is expendable you’d be just as safe handling the cargo planes the same way as you suggest handling the fuel drones.
peckrob 6y ago
More to the point, there's no need because we're already very close to hitting the theoretical maximum flight distance - the point at which you could connect any airport to any other airport - which is slightly less than 13,000 miles [0]. Call it about 12,300. The A-350ULR has a range of a bit more than 11,000 miles [1]. Basically, probably some time in the next decade or so we will break through that barrier and be able to connect any two airports on Earth nonstop if we wanted to. Whether it is economical to do so is another question. [0] http://www.gcmap.com/mapui?DU=mi&P=AGP-AKL http://www.gcmap.com/mapui?DU=mi&P=AGP-AKL [1] https://www.flightglobal.com/a350-900ulr-range-figure-not-a-revision-airbus/123978.article https://www.flightglobal.com/a350-900ulr-range-figure-not-a-...