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Most Efficient Wing In Aviation?  
User currently offlineThrust From United States of America, joined Sep 2003, 2691 posts, RR: 10
Posted (3 years 4 months 5 hours ago) and read 9744 times:

Thought this would be interesting just because of all the new aircraft that have been popping up over the past 20 years. I would personally think it's the A380 wing or the 777 wing, but I'd like some input from others. Feel free to describe any aspects you think make it the most efficient. We're talking about commercial airliners here.


Fly one thing; Fly it well
51 replies: All unread, showing first 25:
 
User currently offlineStitch From United States of America, joined Jul 2005, 31418 posts, RR: 85
Reply 1, posted (3 years 4 months 4 hours ago) and read 9723 times:
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I'd expect it's the A380's wing at the moment, at least as it applies to commercial aviation.

I've heard amazing things about the 787's wing and then we have the A350's on the way.


User currently offlinetravelavnut From Netherlands, joined May 2010, 1667 posts, RR: 7
Reply 2, posted (3 years 4 months 4 hours ago) and read 9711 times:

Quoting Stitch (Reply 1):

I've heard amazing things about the 787's wing

If it is as good as it looks it's gonna be one extraordinary wing!  But the same goes for the A380 wing, head on those gull wings are really something.


If the OP meant Aviation in general I would think the latest generation of gliders would have the most efficient wing.

http://www.tcs-uk.com/dpye/images/Jaca%20Apr%202007_20070407_14-ed-web1.jpg

[Edited 2011-08-25 01:40:49]


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User currently offlineStarlionblue From Greenland, joined Feb 2004, 17176 posts, RR: 66
Reply 3, posted (3 years 4 months 2 hours ago) and read 9648 times:

Easily gliders or some of the Rutan designs for long-distance records like GlobalFlyer and Voyager.

When it comes to efficiency those beat any airliner hands down. Not very good for airliner speeds though.  



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineptrjong From Netherlands, joined Mar 2005, 4005 posts, RR: 18
Reply 4, posted (3 years 4 months 2 hours ago) and read 9620 times:

The question was airliners. Does anyone beat the old Fokker F27/50's aspect ratio 12 wing?


The only difference between me and a madman is that I am not mad (Salvador Dali)
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17176 posts, RR: 66
Reply 5, posted (3 years 4 months 1 hour ago) and read 9584 times:

Quoting ptrjong (Reply 4):
The question was airliners.

A bit ambiguous given the title:

Quoting Thrust (Thread starter):
Most Efficient Wing In Aviation?

But fair enough, airliners. If you're talking pure glide ratio, my bed is on a turboprop.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineCharlieNoble From , joined Dec 1969, posts, RR:
Reply 6, posted (3 years 4 months 1 hour ago) and read 9574 times:

Hard question to answer I think...since the decisions that go into the wing design are dependent on so many other design decisions and external factors.

The 727's wing was pretty efficient if your goal is to cruise really fast and land really slow, and your airplane has the engines back on the tail, but obviously not the best choice overall (or for today's operating environment) or you'd see more aircraft with that kind of setup now.


User currently offlinetravelavnut From Netherlands, joined May 2010, 1667 posts, RR: 7
Reply 7, posted (3 years 4 months 1 hour ago) and read 9572 times:

Quoting ptrjong (Reply 4):
Fokker F27/50's
Quoting ptrjong (Reply 4):
turboprop

Forgive my ignorance. But from my un-informed perspective a turbo-prop wing doesn't seem to be very efficient just by the look of it. Square, low aspect ratio, not the sweeping aerodynamic shape of the 787 or 380. So what am I missing?



Live From Amsterdam!
User currently offlineokie From United States of America, joined Jul 2003, 3188 posts, RR: 3
Reply 8, posted (3 years 3 months 4 weeks 1 day 23 hours ago) and read 9523 times:

Quoting travelavnut (Reply 7):

Forgive my ignorance. But from my un-informed perspective a turbo-prop wing doesn't seem to be very efficient just by the look of it. Square, low aspect ratio, not the sweeping aerodynamic shape of the 787 or 380. So what am I missing


As with anything in aviation there are a lot of trade-offs and constantly evolving.
The question is about the most efficient wing and the answer is that it depends on application and operating regime.
As mentioned earlier the 27 wing was designed to operate in a speed regime of a straight pipe jet with operating speeds near .92 mach.
With the advent of high by-pass turbines then the operating environment dropped down to .84 mach or so. Wing designs were changed to take that into account.
As with say a ATR turbo prop operates down about 250 knots therefore you design a wing to operate in that speed range and you lose your swept design to stay most efficient in that regime.
So as a general rule the answer would be the latest design would be the most efficient for that application and time period.

I sure there a plenty of anomalies in the industry but probably one of the best known of inefficiency was when Dornier replaced the turbo props on the D328 and stuck turbines under the wing and did little to the wing. You ended up with a jet engine for power trying to push a draggy low speed turbo prop wing.

Okie


User currently offlinePITingres From United States of America, joined Dec 2007, 1163 posts, RR: 13
Reply 9, posted (3 years 3 months 4 weeks 1 day 23 hours ago) and read 9520 times:

It might help the discussion if we could define efficiency as applied to wings. Is there a standard definition? I guess you'd want to normalize for wing loading somehow.


Fly, you fools! Fly!
User currently offlineMir From United States of America, joined Jan 2004, 21865 posts, RR: 55
Reply 10, posted (3 years 3 months 4 weeks 1 day 23 hours ago) and read 9509 times:

In the bizjet world, the Citation Sovereign has a pretty impressive wing on it. It'll get a midsize jet off of a 4,000 foot runway, take it all the way up into the 40s, and then go 2800nm at .78 Mach or so.

-Mir



7 billion, one nation, imagination...it's a beautiful day
User currently offlineDashTrash From United States of America, joined Aug 2006, 1563 posts, RR: 2
Reply 11, posted (3 years 3 months 4 weeks 1 day 23 hours ago) and read 9507 times:

I think you're going to find the Citation X hard to beat. Decent low speed efficiency and excellent high speed efficiency. As a comparison when I flew Lear 25s, at FL 450 I think we had around 20 kts between overspeed and stall. Check out the margin at FL510 in the X. It's somewhere between 90-110 kts.


User currently offlinerwessel From United States of America, joined Jan 2007, 2412 posts, RR: 2
Reply 12, posted (3 years 3 months 4 weeks 1 day 19 hours ago) and read 9363 times:
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Quoting PITingres (Reply 9):
It might help the discussion if we could define efficiency as applied to wings. Is there a standard definition? I guess you'd want to normalize for wing loading somehow.

Probably L/D comes closest, although that's usually calculated for the whole aircraft, not just the wing. That does leave intended operating speed out of the equation, though - a Nimbus 4, for example, is certainly very efficient, getting better than 60:1 - but it does that at about 60kts. Airliners are mostly in the 15-20:1 range, although at closer to 200kts. If nothing else very high aspect ratio wings are structurally difficult at high speeds (and by definition lack internal volume).


User currently onlineB777LRF From Luxembourg, joined Nov 2008, 1466 posts, RR: 3
Reply 13, posted (3 years 3 months 4 weeks 1 day 17 hours ago) and read 9304 times:

Concorde, obviously.


From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
User currently offlineHaveBlue From United States of America, joined Jan 2004, 2124 posts, RR: 1
Reply 14, posted (3 years 3 months 4 weeks 1 day 16 hours ago) and read 9240 times:

Quoting Thrust (Thread starter):
We're talking about commercial airliners here.

If you read the OP's initial post, he clearly defines it as commercial airliners.

My vote would go to the 787, just my opinion.



Here Here for Severe Clear!
User currently offlinetimz From United States of America, joined Sep 1999, 6902 posts, RR: 7
Reply 15, posted (3 years 3 months 4 weeks 1 day 15 hours ago) and read 9219 times:

Quoting HaveBlue (Reply 14):
If you read the OP's initial post, he clearly defines it as commercial airliners.

He mentioned a couple airliners like they were candidates for "Most efficient wing in aviation". Maybe he meant to limit it to airliners, but he clearly never said so.

If efficiency means lift-to-drag, no jet will be a contender, will it? So this thread assumes efficiency means something else? Anybody know what?


User currently offlinegigneil From United States of America, joined Nov 2002, 16347 posts, RR: 85
Reply 16, posted (3 years 3 months 4 weeks 1 day 15 hours ago) and read 9211 times:

Quoting B777LRF (Reply 13):
Concorde, obviously.

Concorde was one of the most aerodynamically inefficient vehicles ever built.

NS


User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3598 posts, RR: 66
Reply 17, posted (3 years 3 months 4 weeks 1 day 14 hours ago) and read 9181 times:

Quoting okie (Reply 8):
As mentioned earlier the 27 wing was designed to operate in a speed regime of a straight pipe jet with operating speeds near .92 mach.
With the advent of high by-pass turbines then the operating environment dropped down to .84 mach or so. Wing designs were changed to take that into account.

The 727 wing was more efficient in terms of nautical miles per lb of fuel when operating at 0.84M as opposed to 0.92M. High speeds work when kerosene sells for $0.10 per gal as crew costs are the biggest component of operating costs. When the price goes to $1.00 per gal, you slow down.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineKPWMSpotter From United States of America, joined Dec 2006, 457 posts, RR: 2
Reply 18, posted (3 years 3 months 4 weeks 1 day 13 hours ago) and read 9147 times:

Wow. Well then. The posts above certainly have some wide ranging answers.

Given the vague nature of the question, I don't think there can be any truly right answer. Personally, I'd say an "efficient" wing would be a wing with the highest possible lift to drag (L/D) ratio, as a high L/D will allow the greatest distance traveled with the least power, which in my mind would be "efficient" flight.
Now, as a general rule, L/D is directly related to a wing's induced drag coefficient, which is directly related to the wing's aspect ratio. The higher the aspect ratio wing, the higher the L/D. Right there, that rules out the Concorde and other supersonic, stubby winged aircraft. If we assume Wikipedia's table of L/D ratios to be generally correct, a common tern (bird) is about 3x more efficient through the air than the Concorde at approach speed. A 747 is listed with an L/D of almost 4x that of the Concorde. Supersonic aircraft are designed with operation at supersonic speeds in mind, where reducing wave drag (a result of supersonic shockwaves) is much more important, and where lift coefficients start getting very convoluted. Even though aircraft like the Concorde and F-104 are capable of impressive speeds, they guzzle fuel at a tremendous rate to accomplish their missions. In a power-off scenario, I'd approximate the L/D of the F-104 to be about equivalent to that of a brick.

Assuming that aspect ratio is the primary driving parameter of efficiency, that leaves the contest almost entirely up to sailplanes. Since the focus seems to be on powered aircraft though, I'll narrow my investigation to rule out the super-high performance gliders (the German "Eta" glider probably holds the trophy for the most efficient aircraft in the world at the moment - it can achieve a glide ratio of 72:1 with its 51.3 aspect ratio wing.)

Unfortunately, L/D isn't directly related to aspect ratio, but also to an aircraft's parasite drag (where parasite and induced drag are a minimum, L/D will be a maximum.) Some of an aircraft's parasite drag will be due to the wing, so...it's not really possible to say the highest aspect ratio will be the most efficient. Herein lies the perpetual debate of vortex generators vs clean wings, wing tip fences vs winglets, and all the little trade offs which differentiate modern airliners. While vortex generators may increase drag, they also improve the performance of the wing, and so on. Based on whole-aircraft performance figures, I would have to say that the 787 and A350's wings are pretty close to state-of-the-art, but who knows, maybe the old Fokker pencil-thin wings would beat them in a glide...



Oh, and as an aside, I'm sure many of you are thinking "no way, the straight wing of a Fokker 50 can't be more efficient than the sleek swept 787 wing!!" Sweep has nothing to do with lifting performance or aerodynamic efficiency of a wing. Sweep will certainly affect drag to some extent, but its primary objective is to increase the critical mach number of the airfoil. A swept airfoil will delay the formation of shockwaves to a higher mach number, enabling the wing to still function closer to the speed of sound. At low speeds (less than mach 0.3ish) a straight wing will beat out a swept wing of equal wing area in a glide any day.



I reject your reality and substitute my own...
User currently offlineokie From United States of America, joined Jul 2003, 3188 posts, RR: 3
Reply 19, posted (3 years 3 months 4 weeks 1 day 12 hours ago) and read 9120 times:

Quite impressive there DashTrash.
Particular looking at the AOA.

Okie


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17176 posts, RR: 66
Reply 20, posted (3 years 3 months 4 weeks 1 day 12 hours ago) and read 9117 times:

Lift to drag ratio is one measure. Another is glide ratio unpowered.

Quoting travelavnut (Reply 7):
Forgive my ignorance. But from my un-informed perspective a turbo-prop wing doesn't seem to be very efficient just by the look of it. Square, low aspect ratio, not the sweeping aerodynamic shape of the 787 or 380. So what am I missing?

The sweep actually decreases lift and increases weight. The reason for the sweep is to delay shock wave formation at high subsonic speeds. It's there to allow higher speeds. Since the purpose of the wing is to create as much lift as possible for as little weight as possible I would argue this means sweep is an inefficiency.

If we narrow the question to "... at speeds over M0.85" then certainly a swept wing is more efficient. But if we're talking "best lifting device", a straight wing is more efficient. Turboprops take longer to get there, but they use way less fuel to do it.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineHaveBlue From United States of America, joined Jan 2004, 2124 posts, RR: 1
Reply 21, posted (3 years 3 months 4 weeks 1 day 12 hours ago) and read 9117 times:

Quoting timz (Reply 15):
He mentioned a couple airliners like they were candidates for "Most efficient wing in aviation". Maybe he meant to limit it to airliners, but he clearly never said so.

Um, no.

Again, he clearly stated.... and I quote:

Quoting Thrust (Thread starter):
We're talking about commercial airliners here.

Fairly simple, don't know why you're having trouble grasping it.



Here Here for Severe Clear!
User currently offlineptrjong From Netherlands, joined Mar 2005, 4005 posts, RR: 18
Reply 22, posted (3 years 3 months 4 weeks 1 day 11 hours ago) and read 9086 times:

Quoting travelavnut (Reply 7):
Forgive my ignorance. But from my un-informed perspective a turbo-prop wing doesn't seem to be very efficient just by the look of it. Square, low aspect ratio, not the sweeping aerodynamic shape of the 787 or 380. So what am I missing?

Some of the guys above understand more about this stuff than I do. But building a sleek swept wing is difficult, and so when your definition of efficiency does not include speed, high aspect ratio straight wings are more efficient, more akin to a glider wing. Some turboprops, designed for STOL, have stubby wings, but the Fokker wing was designed for fuel efficiency in cruise. Have another look at it - it's not square and low aspect ratio at all. Its aspect ratio (span^2/wing area) is 12 and that is higher than for any other airliner that I checked, hence my question. Not that I think it's an engineering marvel.


View Large View Medium
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Photo © Shahram Sharifi - Iranian Spotters



[Edited 2011-08-25 18:06:05]

[Edited 2011-08-25 18:06:25]


The only difference between me and a madman is that I am not mad (Salvador Dali)
User currently offlineDC8FriendShip From United States of America, joined Apr 2005, 243 posts, RR: 2
Reply 23, posted (3 years 3 months 4 weeks 1 day 11 hours ago) and read 9083 times:

I would imagine that most of the STOL airliners would be in stiff competition for efficiency. Get off the ground as fast as you can, speed doesn't really count, and land slow.


Come fly the Friendly Skies of United
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 24, posted (3 years 3 months 4 weeks 1 day 9 hours ago) and read 9005 times:

Quoting timz (Reply 15):
Maybe he meant to limit it to airliners, but he clearly never said so.
Quoting Thrust (Thread starter):
We're talking about commercial airliners here

Seems pretty clear to me.

Quoting KPWMSpotter (Reply 18):
Personally, I'd say an "efficient" wing would be a wing with the highest possible lift to drag (L/D) ratio, as a high L/D will allow the greatest distance traveled with the least power, which in my mind would be "efficient" flight.

Since we're restricting discussion to commercial airliners (which the OP did clearly state), L/D isn't the right metric. You have to turn that into cost...something like $/nm normalized to weight, somehow, would be something like the right measure.

Tom.


25 Post contains links Wingscrubber : The efficiency of a wing depends on how hard it's working and how fast it's going, so the context is important to figure out how much drag it will enc
26 Thrust : Feel free to answer in both respects...i actually had originally meant in aviation in general, but then as I was typing decided I wanted to know about
27 Thrust : I'm also curious as to what narrow-bodied airliners like the 757, 737, and the narrow-bodied Airbuses tend to feature conservatively swept wings where
28 rwessel : The A380 (33.5 degrees) has considerably less wing sweep than the 747 (37.5), a bit less than the DC-10s (35) and a bit more than the L10-11's (32).
29 MD-90 : Good god that's efficient. I've always been a fan of the Stemme S-10VT myself and am amazed at how it can manage a 50:1 glide ratio with a side-by-si
30 Post contains links rwessel : Of course the Eta is self-launching, so it *is* powered. http://www.leichtwerk.de/eta/en/gallery/photos.html That's a lot of wing. 101.4ft to be exac
31 Post contains images hal9213 : I would say the most efficient wing is having no wings and fly by thrust alone!!!!!
32 Post contains images KPWMSpotter : Well, not exactly. Wing sweep may reduce drag to a minimal extent, but generally sweep is designed into an aircraft to increase speed; specifically t
33 Rara : Blimey, that's quite impressive. About how high would true airspeed be at that point?
34 rwessel : The problem with supersonic flow and its associated shock waves, is the resulting wave drag. Several aircraft have done odd things like that to the w
35 Post contains images lightsaber : If we re-open to non-commerical. I would say the latest Global Hawk. But one has to include the whole aircraft. For example, a lifting nose (1st impli
36 Post contains images rcair1 : How well do you sleep? I'd need a quieter place.... Sorry - couldn't resist....
37 Rara : Answered my own question - about 467 knots...
38 Thrust : That leads me to ask then, does the A340 have such a slow climb and acceleration rate solely because of it being underpowered, or is the degree the w
39 Thrust : I'm also slightly curious about the 727's wing, since it is one of the only narrow-bodies I've ever heard of to have sharply swept. It had a very high
40 Post contains images Starlionblue : It is not underpowered. It meets certification and customer requirements just fine. It's just a bit of a Yugo in the thrust to weight department. Com
41 Post contains links 474218 : Quoting rwessel (Reply 28):The A380 (33.5 degrees) has considerably less wing sweep than the 747 (37.5), a bit less than the DC-10s (35) and a bit mor
42 MrChips : The only thing that comes close in terms of efficiency would be a Gulfstream, specifically the upcoming G650. The wings on most modern corporate jets
43 tdscanuck : It's not underpowered, it just gets used on long- and ultra-long haul flights a lot so it's usually taking off at a higher % of MTOW that most other
44 DashTrash : Probably around 420-440. Normally we're at 520 in the high mach numbers.
45 OldAeroGuy : A good measure of efficiency is M(L/D). This explains the differences between a wide range of aerial vehicles: Powered sailplane: M=.15 L/D=50 M(L/D)=
46 Post contains links and images Fly2HMO : I can't believe nobody has mentioned this: From what little I recall from aerodynamics class, flying wings were supposed to be by far the most efficie
47 tdscanuck : Flying wings, in general, are very efficient. The B-2 has some severe aerodynamic compromises to protect the stealth features though. Split ailerons
48 gigneil : As usual, utter crap. The A340 has a very competitive wing loading, and more than enough power to lift its heft. Its just not overpowered, it just do
49 faro : True, although one must bear in mind that it was initially due to be powered by the SuperFan; I'm willing to wager that it would have had even better
50 ptrjong : The aircraft is very efficient through having no fuselage. Looking at it as a wing, it is probably somewhat compromised.
51 gigneil : Truly a sad day when you can't see (or hear) one take off again. No argument. NS
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