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In a typical airplane, one of the main flight control mechanisms are the ailerons/flaperons, which allows one to tweak the lift/drag profile of both wings independently.

I was wondering about the feasibility of achieving similar flight control by means of rotating an entire wing around its lengthwise axis. As I understand it, such tweaking of the aoa would have very similar flight control characteristics as regular ailerons.

Obviously this is a somewhat awkward design mechanically; the point where the wing meets the fuselage is one of the most heavily stressed parts of the airplane, so to add a pivot there takes some consideration. But I am thinking here in the context of an RC plane; where i think just nesting two carbon tubes at the center of lift will work fine.

Some potential advantages are that while the static loads on the articulated part will be high, the forces required to actuate the mechanism could be lower or approach zero, assuming the center of lift can be held reasonably constant. Also, ailerons are aerodynamically awkward and draggy when not in neutral position; moreso than an airfoil tilted tilted from its optimal L/D. Mostly I am just curious though, what something like this would look like in practice.

I cant seem to find anything on google about a design like this, but surely someone must have tried this before? If not, there must be good theoretical reasons I am missing why we should expect this to be a disaster. Is there a search term anyone is aware of that would lead me to similar designs?

Rodrigo de Azevedo
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Eelco Hoogendoorn
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  • Welcome! I think the question has been already asked, but can't retrieve it. Related: Are there any contemporary advantages in favor of wing warping? – mins Nov 29 '17 at 15:47
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    @mins This one? – Pondlife Nov 29 '17 at 16:08
  • @Pondlife: That a good one, but I was thinking about one where I believe Peter answered something about robustness of the axle. – mins Nov 29 '17 at 16:11
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    @mins maybe this one – user721108 Nov 29 '17 at 16:16
  • @qqjkztd! Bingo! – mins Nov 29 '17 at 16:17
  • rotary wing aircraft - a.k.a. helicopter – Steve Kuo Nov 29 '17 at 16:30
  • There are quite a lot of RC planes using full variable incidence wings to control roll, getting rid of ailerons and providing one perfectly smooth airfoil, eliminating parasite drag due to ailerons. However one should take attention to max positive & negative angle of attack: In order to avoid too much inverse yaw behavior at high angle of attack: it may be safer to mechanically force negative incidence wing to have a smaller deflection angle, than positive incidence wing. Coupling this (mechanically again) to elevator position, will allow safe behavior in both reverse and normal flight. – user721108 Nov 29 '17 at 16:54
  • It's also possible to control pitch, using variable wings. Horizontal stabiliser becomes one static device. – user721108 Nov 29 '17 at 16:58
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    Some fixed-wing aircraft have that 'tilting wing', like the French 'Pou du Ciel', designed in the 1930s and still flying around... – xxavier Nov 29 '17 at 17:54
  • Thanks for the answers guys; hadnt heard of the Pou du Ciel before, but that concept mashes really well with the direction I was thinking in... now i want to build one... – Eelco Hoogendoorn Nov 29 '17 at 21:34
  • in WWII, the germans designed a high-wing cargo plane with a variable-incidence wing like you describe. this allowed them to construct a fuselage that didn't need a kicked-up empennage (to clear the runway during rotation); instead, when they were ready to take off, they rotated the entire wing and the plane flew off the ground with the fuselage level with the runway. this arrangement had no outstanding performance advantage over a conventional design and was mechanically complex, so it was not pursued further. – niels nielsen Nov 29 '17 at 21:56
  • Vought F-8 Crusader also has variable incidence wing, up to +7°, increasing lift without compromising forward visibility, but also avoiding tail strikes while taking off or landing. In some way, Concorde also has a variable incidence wing, relative to the canopy. – user721108 Nov 30 '17 at 13:09
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    @qqjkztd - There are names for these type of model aircraft, most of which are rc gliders. "Wingeron" - the wings control roll, but there's an elevator to control pitch. "Pitcheron" - the wings control pitch and roll, with a fixed horizontal stabilizer instead of an elevator "Pitcheron" models require transmitter "smart" enough to control the wing servo motors independently. The servo response to roll control inputs can be adjusted to get rid of adverse yaw. – rcgldr Nov 30 '17 at 15:43
  • @nielsnielsen: Do you happen to know the manufacturer, name or RLM number of this cargo aircraft? – Peter Kämpf Jan 05 '18 at 01:10
  • No, I do not. I read about it in a text documenting pre-WWII German aeronautical engineering technology. it was a twin-engine, high-wing, cargo plane developed after the spanish civil war and before or during WWII. – niels nielsen Jan 05 '18 at 01:56
  • The very first aircraft ever, (the Wright Flyer), controlled roll by twisting the wings. https://wright.nasa.gov/airplane/flyer.html – Charles Bretana Jun 01 '18 at 13:27
  • This question has now been duplicated here (with at least once answer) -- https://aviation.stackexchange.com/q/97242/34686 – quiet flyer Feb 01 '23 at 16:26

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Yes, it has been tried before and is regularly used on many horizontal and even some vertical tails.

However, in subsonic flight an elevator will offer better efficiency. Only in supersonic designs is the full-flying tail the clearly preferred option.

To move the whole wing needs very strong hinges and actuators, but there were some which did even this:

  • Mignet HM 14 Pou du Ciel (picture source). It was light and flew slowly enough that moving the whole wing was not an issue.

Mignet HM 14 Pou du Ciel

enter image description here

Even all-moving outer wings have been tried for roll control, albeit in only very few aircraft. Three I know of (and all of them were built once only) are:

Short SB.4 rotated wingtip

Peter Kämpf
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  • Just one note on the F8 crusader: the movable wing was actually a design feature to decrease the approach speed of the aircraft in order to better facilitate carrier operations all while providing a good wing for supersonic flight. – Romeo_4808N Jun 01 '18 at 19:18
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    @CarloFelicione The same approach speed could be had by rotating wing + fuselage by those seven degrees, with the only difference that fuselage attitude would be seven degrees higher. – Peter Kämpf Jun 01 '18 at 23:23
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I have just come across this site and the question regarding mainplanes with individually controlled incidence instead of ailerons, so I registered and here's my ten-cents worth!

In my opinion, there seems little point in differential movement of the entire wing when rolling torque is best applied near the tips and not at the root, except maybe in small devices like missiles, models or relatively slow moving light aircraft. However, in larger aircraft the complexity and stress of the wing attachment points and insurmountable complications arising from wing mounted engines, fuel tanks, high-lift devices and especially landing gear, I would certainly favour conventional ailerons as aeronautical development over the years seems to have proved.

However, as to the history of the idea of rotating an entire wing around its lengthwise axis:

There have been several aircraft made using this principal over the years, starting around 1895 in the USA with Dr. George A. Spratt and later with his son George G. Spratt, they experimented with & built a large number of successful gliders, flying boats, land planes and even flying automobiles as joint ventures with Bendix, Consolidated and Bill Stout. All were aimed toward stable aircraft and safer aircraft control systems, and all of them used control wings in some fashion.

See Spratt entry in Aerofiles (sorry, it's near bottom of page) http://aerofiles.com/_sk.html

Note that there appears to be some confusion in designations as Aerofiles list only goes up to Model 107, but a Spratt 108 Controlwing (looking rather like a development of the 105, but maybe a typo) is on display in the Mid Atlantic Air Museum here: http://www.maam.org/aircraft/spratt.htm

Pictures and more info at: http://1000aircraftphotos.com/Contributions/BlackTed/9933.htm

Next there was the Cornelius LW-1 [X13706] of 1933, that to quote Aerofiles "was an improved version of the earlier Fre-Wing, this one without ailerons, as individually-controllable wings were used in this role". Side view here: http://www.aerofiles.com/corn-lw1.jpg

The above mentioned predecessor the Cornelius Fre-Wing [X182W] (spelling as registered but sometimes spelled Freewing). Good three quarter view here: http://www.aerofiles.com/cornelius.jpg This had variable-incidence parasol wing panels hinged at the centre section, but also had "Trailing ailerons" that actually appear to be aerodynamic tabs mounted on mini booms (presumably operated by the pilot to drive the pivoting wings rather than directly, which may have been too coarse and less controllable, but that's just my conjecture though as I have never seen any photos of this or the LW-1 in flight with differential incidence on view).

Maybe the most modern that I have seen is this French creation, Daniel Dalby's "Dragon One" picture and info here: http://www.pouchel.com/english/index_eng.php?p=dragon_eng.html which it is said was possibly inspired by his earlier APEV Pouchel II

There's a brief video here

There's no real sign of the differential action :-( but at only +2°/-4° I guess it won't be too obvious! However, it does look quite stable, but I would have loved to have seen it turn and bank away! :-)

As the name of its predecessor translated to "Ladder Flea" and Spratt's flying car was nicknamed Flying Flea, I delved a bit on that theme and found this interesting site https://sites.google.com/a/flyingflea.com.ar/www/home/traditional-fforg-menu-1/spratt

It is mostly about Spratt's work and some others I've already mentioned. However, there are numerous links that I haven't explored yet and right at the bottom a link to a modern UAV and mention about a manned version, the Schmittle Aircraft Freewing MK-5 but the link is dead! However, these "Freewings" appear to be more of a self-controlled stability augmentation and stall prevention devices rather than a direct means of control and needs further digging :-)

I hope that this post, although it may not directly answer the initial question posed, it should help in showing the various attempts made to use the principle over the years.

Cheers,

TC

SincoTC
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    Could you remove some of the fluff and get to the point a little more please? – dalearn Jun 01 '18 at 12:54
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    @dalearn: Eelco Hoogendoorn asked the question about "flight control by means of rotating an entire wing around its lengthwise axis" and concluded by saying "I cant seem to find anything on google about a design like this, but surely someone must have tried this before?" As most of the answers above referred to wing warping or changing the incidence of the entire wing, not rotating the wings independently, my "Fluff" answers and illustrates his latter question, but I take your point, I do tend to waffle a bit :-) – SincoTC Jun 01 '18 at 14:00
  • The content is fine in my opinion, it is just the extra stuff that is unrelated to the answer that I was asking about. e.g. perhaps you could get to the point a little faster or format your answer so that it is helpful for the next person who comes along. – dalearn Jun 01 '18 at 15:01
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    Thank you for adding not one but several designs! – Peter Kämpf Jun 01 '18 at 19:02
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This has been done quite a bit on model airplanes, best suited for slope-soaring gliders or small aerobatic powered planes. It means that full control can be achieved using just two servos and no (weighty) linkages to the tail surfaces. See:

for a beautiful example applied to an antique model design. The servos are externally mounted under the wing leading edges. A carbon wing joining rod serves as the hinge.
Stefan Mochnacki
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Rotating an entire wing to do the job of an aileron is overkill. Ailerons as they have been designed for years can flip a plane 90 degrees from horizontal in less than a second.

Why go thru the hassle when a small control surface will do the job without the huge expense of design?

Doug Ryan
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  • Charlie Kaman applied your point to rotary wings, and it worked. – KorvinStarmast Jan 06 '18 at 04:04
  • My initial question was mostly academic; to deepen my understanding. You are right that rotating the entire wing around the root is indeed probably a poor idea on first principles, since it will require a very heavily loaded yet actuated joint. There are ways to design around that as the pou du ceil shows though. And ailerons have their disadvantages, such as draggy non smooth flow when extended, and loss of control in a stall. – Eelco Hoogendoorn Jun 01 '18 at 21:30
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The very first aircraft to fly, (The Wright Flyer) controlled roll by twisting or warping the wings.

Charles Bretana
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