Mid-Air Refueling of Passenger Aircraft?

[AA 1818]

Hi All,

Ok, so I want to bounce an idea off of you guys, and see not only if it is practical, but economical, possible and worth while.

So, I have this idea - that instead of making planes haul all of their fuel in-flight, that we develop a way to allow aircraft to fuel after takeoff via in-flight fueling. Sorta like a fueling station in the sky. I was earlier thinking of having KC-135s flying around out there, but perhaps another format would serve better.

It would allow aircraft to take off with more weight, and then burn less fuel in the take off process. It would also allow certain aircraft to fly much longer routes, and would allow some airport to deal with emergency situations differently.

So, am I being completely daft here? Has this been discussed/studied elsewhere already? How could this work out? And, should it?

[Gabriel]

I think that your idea can't beat a fuel stop, at least in terms of $$$$$$

[Peter Kesternich]

You also need to consider the fuel that the tanker uses. So, no matter what, the weight of the fuel has to take off at some point.

[3WE]

Originally Posted by Gabriel

I think that your idea can't beat a fuel stop, at least in terms of $$$$$$

-Expensive fuel tanker...
-Burning a lot of expensive fuel itself (as Peter says)...
-Requiring all the normal, expensive airliner maintenance...
-Staffed by an expensive crew...
-Expensive, special training for two flight crews...
-Extra crew member on one or both aircraft...(tanker has a "boom pilot")
-Expensive, special plumbing on both aircraft...
-Requiring special ATC assistance...
-A certain elevated safety risk...
-10-zillion expensive hoops and certifications to work through for permission to do this...

...or a truck and a rampie...

[TeeVee]

not to mention (and i'm surprised evan has already jumped on this!) the incredible risk to pax.

[Gabriel]

Originally Posted by TeeVee

not to mention (and i'm surprised evan has already jumped on this!) the incredible risk to pax.

Check again:

Originally Posted by 3WE

-A certain elevated safety risk...

[bob m]

Perhaps it could be feasible for air craft larger then say an A380, one thing for sure, these types of discussions will be part on our energy future.

Bob

[TeeVee]

Originally Posted by Gabriel

Check again:

uh yeah, missed that. damn bourbon!

[Gabriel]

Originally Posted by bob m

Perhaps it could be feasible for air craft larger then say an A380, one thing for sure, these types of discussions will be part on our energy future.

Bob

I very much doubt it.

If A and B are too far apart, going from A to B takes a lot of fuel.
But the amount of fuel you can take in an airplane is limited by the amount of payload (passengers and cargo) that you take, and vice versa: You can't just fill it up with fuel AND payload (both to max capacity) because you would be exceeding the max gross weight. Thus in short flights you can take more cargo and a long flight that requires more fuel you can't take as much cargo. In this case taking a lot of fuel directly limits your revenue.

And even if, due to demand, after selling all the payload that you can you still have room for all the fuel, you need fuel just to carry fuel (the last pounds of fuel that you're going to use just before landing, taking them from sea level to 41000ft and the all across the Pacific ocean is not free).

So even in this case (payload not penalized) it could be more economic and ecologic to depart with less fuel that required for the whole trip and get more fuel along.

But, by all means, making a fuel stop will be much more economical (and environmentally friendly) than operating an aerial gas station. The fuel stop will add time to the trip, perhaps one hour or more, but that's not so much in a 15 hours flight.

And, as TeeVee said, all that assuming that in-flight refueling achieves a level of safety good for passenger flights.

[3WE]

Originally Posted by Gabriel

I very much doubt it.

If A and B are too far apart...

Wouldn't there be some way a conveyor belt could be used?

[Felipe Garcia]

Originally Posted by Gabriel

If A and B are too far apart, going from A to B takes a lot of fuel.
But the amount of fuel you can take in an airplane is limited by the amount of payload (passengers and cargo) that you take, and vice versa: You can't just fill it up with fuel AND payload (both to max capacity) because you would be exceeding the max gross weight. Thus in short flights you can take more cargo and a long flight that requires more fuel you can't take as much cargo. In this case taking a lot of fuel directly limits your revenue.

And we know how well those reduced cargo capacity, ultra long range aircraft sold (A340-500, 772LR).

[porter guy]

also, think about how many aircraft that are going to need fueling. You'd need to clog up airways with tankers in airways that are already so congested that a single wrong move could cost hundreds of lives.

We're talking at least 100 tankers per airport that has departures at least every minute.

[ali2128]

B777-200LR anyone?

[guamainiac]

What runs would be the prime candidates? Are there any real world examples where this would possibly be practical?

[Foxtrot]

As has already been pointed out, the 77L and other much fuel efficient aircraft in service these days are plenty enough for the job. Besides, I don't think passengers would really want to spend 20+ hours in a cramped space, the 15+ hour flights operated by some carriers today are generating complaints as is. I know I wouldn't.

And we know how well those reduced cargo capacity, ultra long range aircraft sold (A340-500, 772LR).

Actually the 77L is selling better, it's the 345 that's been the fuel guzzler and is such, not as popular.

[brianw999]

Originally Posted by 3WE

Wouldn't there be some way a conveyor belt could be used?

Somethng like....oooooh.....let's call it a train shall we ?

[3WE]

Originally Posted by brianw999

Somethng like....oooooh.....let's call it a train shall we ?

No, no...somehow the plane lands on a conveyor belt, or the fuel truck goes on the conveyor belt...or something like that...

[Foxtrot]

^That idea has its own problems, and besides, a lot of these conveyor belts would be required for just transferring fuel trucks from point A to point B. The better option is one that is frequently used by travellers in Europe: take a connecting train after landing. Of course not saying this would be done everywhere, just where the infrastructure/code-share agreements are already in place.

[Gabriel]

Originally Posted by 3WE

No, no...somehow the plane lands on a conveyor belt, or the fuel truck goes on the conveyor belt...or something like that...

Wait a minute, we could combine that idea with Brian's train.

1- You have a very long track.
2- A somehow long train (a couple of fuselage lengths) waits at the "approach end" of the track.
3- When the plane approaches, the train accelerates to Vref in a synchronized way so it reaches that speed just as the plane overflies it.
4- The plane lands atop the train (which is of course especially designed for that) and the refueling process starts.
5- The train keeps going at Vref during the refueling.
6- Once the refueling is complete, the pilot just pulls up and up it goes.

[brianw999]

^^^

Why not, I've seen a Piper Cub land on a trailer drawn by a car !

http://youtu.be/40KxTPqcEZg

....... and a Cessna float plane get off of a hard runway in a novel manner....

http://youtu.be/Temm5lI-zUI