Could flight control be achieved by rotating a wing entirely?

Question

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?

Answer 1

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.

• The Vought F-8 "Crusader" and XF8U-3 "Corsair III" could jack their wings seven degrees up in order to improve fuselage attitude and pilot visibility during take-off and landing (picture source).

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:

• Granger Archaeopteryx,
• Short SB.1 glider, and
• Short SB.4 Sherpa, the rotated wingtip of which is shown below (picture source).

Answer 2

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

Answer 3

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.

Answer 4

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?

Answer 5

The very first aircraft to fly, (The Wright Flyer) controlled roll by twisting or warping the wings.