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The Military Transportation Science Technology

Air Force Lab Test Out "Aircraft Surfing" Technique To Save Fuel 205

coondoggie writes "It's not a totally new concept, but the Air Force is testing the idea of flying gas-guzzling cargo aircraft inline allowing the trailing aircraft to utilize the cyclonic energy coming off the lead plane — a concept known as vortex surfing — over long distances to save large amounts of fuel. According to an Air force release, a series of recent test flights involving two aircraft at a time, let the trailing aircraft surf the vortex of the lead aircraft, positioning itself in the updraft to get additional lift without burning extra fuel."
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Air Force Lab Test Out "Aircraft Surfing" Technique To Save Fuel

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  • What about the lead aircraft? Does he run out of gas first and crash and burn, leaving a new lead to continue the cycle?

    • Re: (Score:3, Insightful)

      by Anonymous Coward

      Just because the lead craft doesn't get to save gas, doesn't mean there is not a net gas savings for the entire system.

    • by Freddybear ( 1805256 ) on Thursday October 11, 2012 @05:00PM (#41623513)
      Change positions every so often. It's more fun that way. ;)
    • Re: (Score:3, Funny)

      by Morpf ( 2683099 )

      You can switch lead on-the-fly.

    • Re:Who's up first? (Score:4, Interesting)

      by NEDHead ( 1651195 ) on Thursday October 11, 2012 @05:01PM (#41623525)

      Actually, in most examples of drafting, the benefit extends to the leader as well, reducing the tail drag associated with a solo player. As I recall, the benefit generally increases as you add cars to the train as the lead drag and tail drag are spread over more units.

      • Given the distance involved (200 feet or so) I doubt that effect will be present in aircraft "vortex surfing". I think the physics involved are quite a bit different from drafting in a car, but that is really just a guess.

        • by nairnr ( 314138 )
          The vortices of planes last a long time. At airports when you are dealing with the big planes they have to leave minutes later so that the vortices have time to dissipate. Otherwise there is severe turbulence for the next plane. Watch a plane coming down through fog and see how long it takes for it to settle down...
      • Re:Who's up first? (Score:5, Insightful)

        by AK Marc ( 707885 ) on Thursday October 11, 2012 @05:15PM (#41623749)
        Firstly, this isn't drafting. Secondly, the lead would likely swap periodically, as birds have done for thousands of years. Drafting airplanes won't work for the same reason helicopters hovering can crash wile under full power (google "settling with power" for an areodynamic description of what would happen when multiple wings travel through the same air). Yes, I am a pilot.
        • Re: (Score:2, Informative)

          by NEDHead ( 1651195 )

          Of course it is drafting. It relies on mitigating the detrimental vortex effects associated with moving object terminations in a fluid environment by spreading the wasted energy over a longer object. Same as the efficiencies of longer boats in water, and longer props, whether on planes or windmills. No different in concept.

          • Re:Who's up first? (Score:5, Informative)

            by AK Marc ( 707885 ) on Thursday October 11, 2012 @06:19PM (#41624559)
            Drafting, defined as "following someone/something in a manner to reduce your aerodynamic drag by traveling in air moving at a lower relative velocity" excludes this act.

            If you feel it is drafting, please state the definition of drafting you are using, as I've not seen a definition of drafting that would include this.

            It does not depend on mitigating detrimental vorticies. NASCAR drafting does, and the lead car gets the benefit from the reduced drag. This does not benefit the vehicle in the front and is the following car using a predicted vortex to its advantage, while traveling through otherwise undisturbed air. Thus "drafting" where the folower uses the lead car to "break the air" is not happening.

            Rather than having to define "drafting" to a bunch of morons who are too stupid/lazzy to google, I'd rather discuss the efffect of this on commercial aircraft for the rest of us, flight lanes with airplane flocks saving fuel. Or discussions on how much the winglets affect this effect. But no, it's all a discussion of the definition of "drafting" with a bunch of google-illiterite people.
        • Secondly, the lead would likely swap periodically, as birds have done for thousands of years.

          But isn't that because birds get tired? Planes don't get tired - the lead plane will just burn more fuel than the rest, but as long as it's got enough for the trip, why does it need to swap out?

          • by Xenx ( 2211586 )
            The reason to rotate lead would be to conserve fuel for all planes, so you can travel further on the same size tank.
          • But isn't that because birds get tired? Planes don't get tired - the lead plane will just burn more fuel than the rest, but as long as it's got enough for the trip, why does it need to swap out?

            Migratory birds like geese have insane flight muscles, composed almost entirely of red muscle, and they are not really susceptible to muscle fatigue. The main limitation for them is fuel.

            So the reason planes would want to swap leaders is more or less the same reasons as the birds do: To increase the range of all members of the formation.

            • combat formation flying during WWII was about far more than making impressive shadows to scare the enemy. Bomber crews learned fairly quickly that wingtip drafting extended the range of every bomber in the squadron - albeit only by about 1-2%, but this was enough to afford the pilots some wriggle room during cannon fights. The lead was by relay: the lead bomber would peel up about 100 feet and throttle back to the rear, the new lead taking the next thirty or forty miles.

              source: a distant relative was a wais

          • by AK Marc ( 707885 )

            as long as it's got enough for the trip, why does it need to swap out?

            To share. You should always be fuel limited (even if that includes a buffer/reserve). So if you have a fixed maximum, then using less increases range. So you extend the range of two airplanes if they swap out. If they don't swap, then the range is limited to the range of the one with the lowest range (the front one). Like birds, swapping with planes extends the range of the flock.

        • "thousands of years"? Come on, at least give me "tens of thousands of years". Modern birds have been around for 150,000,000 years; even if it took 99.9% of that time to develop this flocking behavior, we're beyond "thousands of years".
          • by AK Marc ( 707885 )
            Things that weren't observed by humans and documented didn't exist. I would have put "millions" but I expected people to complain about that, as we couldn't have known that far back, and the earth is only 6000 years old, and all that.
        • by QQBoss ( 2527196 )

          Bah, slip of the mouse and modded this redundant... Bye bye, wasted mod points, you had such a short and not so fruitful life...

    • You could have them change off every so often, so none are in the lead for the full time. But that's really only if you're doing this to extend your range. If your concern is mainly decreasing costs, you would just fly them like this, but within the range of a solo aircraft. You would probably even fuel up each craft with enough fuel to handle it solo, just in case something happens.

    • Put more fuel or less cargo in the lead aircraft.

    • by zill ( 1690130 )
      Apparently birds could figure this one out on their own, yet you can't.
  • I wonder if you could start using something like this for commercial aircraft. With careful scheduling, you can have aircraft flying in adhoc formations when they are traveling the same corridors.
    • by Jeng ( 926980 )

      Companies operating commercial aircraft have different regulations about how they fly vs the military.

      If this were ever used commercially, I don't think it would be allowed with passenger aircraft, just cargo. The risk is just too damn high for so little reward.

    • by nairnr ( 314138 ) on Thursday October 11, 2012 @05:36PM (#41624051)
      No, there are strict rules for vertical and horizontal separation for planes depending on VFR/IFR [] Not likely this will be changed anytime soon for safety reasons...
      • That was made so independent planes don't crash in to each other. In theory planes flying in this formation will be working in concert and may have computer/radar control over each other. It's likely a whole new set of rules would need to be drafted for this kind of operation. Honestly it makes the most sense for cargo planes flying over the open ocean to use a system like this. They stand to get the biggest gains, and present the least amount of danger to others that way.

    • by es330td ( 964170 )
      IFR lets aircraft fly through clouds wherein visibility extends no farther than the windshield. You could not pay me enough to be the trailing pilot flying through a cloud formation close enough behind a plane to draft/wingtip vortex surf. I get tense enough IFR in the clouds without also worrying about colliding with another plane.
  • by __aaltlg1547 ( 2541114 ) on Thursday October 11, 2012 @05:00PM (#41623515)
    What could go wrong?
  • In order to expand our pool of aeronautic expertise, the USAF is offering research positions to those with experience at bicycling long distances. ...Or something like that.

  • Mythbusters (Score:5, Interesting)

    by Zordak ( 123132 ) on Thursday October 11, 2012 @05:06PM (#41623609) Homepage Journal
    I see folks at the DoD have been watching Mythbusters. As well they should.
  • by superstick58 ( 809423 ) on Thursday October 11, 2012 @05:08PM (#41623643)
    We're caught in his jetwash! Flame out! We're going in a flat spin! Eject! Eject! Hightway to the danger zone!
  • by Anachragnome ( 1008495 ) on Thursday October 11, 2012 @05:48PM (#41624201)

    The Airlines should take notice.

    Judging by the formations of geese and pelicans I've watched flying by in large groups, I have to assume this effect can be carried from one flyer to the next in a chain and isn't confined to just two flyers. The next question would be "Do all trailing flyers receive this 10% fuel savings, or is there some sort of diminishing return at play?"

    If all of the flyers receive the savings, then the airlines might find that sending a small squadron of aircraft, say five DC-10 sized aircraft in formation as opposed to one large "super-liner", is economically beneficial both in terms of lower costs AND lower CO2 emissions. It would also relieve a common problem with current flight scheduling--empty seats. If the "flight" (I'm referring to the squadron idea) did not sell all the seats, they could simply send one less plane--it allows for options in balancing demand vs resource allocation, which would, I assume, allow the airlines to lower costs across the board including ticket prices. It would also allow the airlines to scale specific routes based on demand more accurately--if there is a sudden surge in demand on specific route, they simply increase the squadron size as required.

    There is the added benefit of "diluting" the severity in repercussions as a result of mechanical failures/human error--when a super-liner suffers catastrophic failure, everyone dies. In a squadron of planes, a failure on one craft wouldn't mean the death of everyone. Not putting one's eggs in one basket has it's benefits.

  • Wait a Minute (Score:4, Interesting)

    by mk1004 ( 2488060 ) on Thursday October 11, 2012 @05:56PM (#41624291)
    Why don't they just install winglets like the airlines are doing? Winglets reduce fuel usage by minimizing the drag associated with the creation of the vortexes. You get the benefits, even if just one plane is flying.
  • by AC-x ( 735297 ) on Thursday October 11, 2012 @06:27PM (#41624617)

    They've been talking about doing this for years [].

  • by dorpus ( 636554 ) on Thursday October 11, 2012 @07:37PM (#41625325)

    I remember an airplane crash near Pittsburgh in the early 1990s, when a plane got too close to another plane and got caught in the wake, causing the plane to plunge.

    • by ZosX ( 517789 )

      Flight 427 was actually the result of a faulty rudder ending up locked in an extreme position. The plane toppled over and plunged straight into the ground. Initial speculation was the wake of another pane as they had not discovered the rudder defect yet.

  • You get the most savings at distances that would probably be dangerous due to turbulence. But even further out, you still realize some savings from the formation.

I THINK MAN INVENTED THE CAR by instinct. -- Jack Handley, The New Mexican, 1988.