Wing configuration

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The Spitfire wing may be classified as: "a conventional low-wing cantilever monoplane with unswept elliptical wings of moderate aspect ratio and slight dihedral". Spitfire.planform.arp.jpg
The Spitfire wing may be classified as: "a conventional low-wing cantilever monoplane with unswept elliptical wings of moderate aspect ratio and slight dihedral".

The wing configuration or planform of a fixed-wing aircraft (including both gliders and powered aeroplanes) is its arrangement of lifting and related surfaces.

Contents

Aircraft designs are often classified by their wing configuration. For example, the Supermarine Spitfire is a conventional low wing cantilever monoplane of straight elliptical planform with moderate aspect ratio and slight dihedral.

Many variations have been tried. Sometimes the distinction between them is blurred, for example the wings of many modern combat aircraft may be described either as cropped compound deltas with (forwards or backwards) swept trailing edge, or as sharply tapered swept wings with large leading edge root extensions (or LERX). Some are therefore duplicated here under more than one heading. This is particularly so for variable geometry and combined (closed) wing types.

A forward-swept-wing Sukhoi Su-47 alongside the more conventional swept-back Su-27 and Su-30MK2. Sukhoi Su-47 in formation, 2005.jpg
A forward-swept-wing Sukhoi Su-47 alongside the more conventional swept-back Su-27 and Su-30MK2.

Most of the configurations described here have flown (if only very briefly) on full-size aircraft. A few theoretical designs are also notable.

Note on terminology: Most fixed-wing aircraft have left hand and right hand wings in a symmetrical arrangement. Strictly, such a pair of wings is called a wing plane or just plane. However, in certain situations it is common to refer to a plane as a wing, as in "a biplane has two wings", or alternatively to refer to the whole thing as a wing, as in "a biplane wing has two planes". Where the meaning is clear, this article follows common usage, only being more precise where needed to avoid real ambiguity or incorrectness.

Number and position of main planes

Fixed-wing aircraft can have different numbers of wings:

Monoplane low.svg
Low wing
Monoplane mid.svg
Mid wing
Monoplane shoulder.svg
Shoulder wing
Monoplane high.svg
High wing
Monoplane parasol.svg
Parasol wing

A fixed-wing aircraft may have more than one wing plane, stacked one above another:

Biplane wire.svg
Biplane
Biplane unequal span.svg
Unequal-span biplane
Sesquiplane.svg
Sesquiplane
Sesquiplane inverted.svg
Inverted sesquiplane
Busemann biplane.svg
Busemann biplane in cross-section
Triplane.svg
Triplane
Quadruplane.svg
Quadruplane
Multiplane.svg
Multiplane

A staggered design has the upper wing slightly forward of the lower. Long thought to reduce the interference caused by the low pressure air over the lower wing mixing with the high pressure air under the upper wing; however the improvement is minimal and its primary benefit is to improve access to the fuselage. It is common on many successful biplanes and triplanes. Backwards stagger is also seen in a few examples such as the Beechcraft Staggerwing.

Biplane unstaggered.svg
Unstaggered biplane
Biplane staggered.svg
Forwards stagger
Biplane backwards staggered.svg
Backwards stagger
Cruciform wing weapon.svg
Cruciform wing weapon
Wing X rotor.svg
Cruciform rotor wing or X wing rotor

Support

To support itself a wing has to be rigid and strong and consequently may be heavy. By adding external bracing, the weight can be greatly reduced. Originally such bracing was always present, but it causes a large amount of drag at higher speeds and has not been used for faster designs since the early 1930s.

The types are:

Monoplane mid.svg
Biplane cantilever.svg
Cantilever
Monoplane strut.svg
Biplane strut.svg
Strut braced
Monoplane wire.svg
Biplane struts-plus-wire.svg
Wire braced
A braced multiplane may have one or more "bays", which are the compartments created by adding interplane struts; the number of bays refers to one side of the aircraft's wing panels only. For example, the de Havilland Tiger Moth is a single-bay biplane where the Bristol F.2 Fighter is a two-bay biplane. [3]
Biplane struts-plus-wire.svg
Single-bay biplane
Biplane two bay.svg
Two-bay biplane
Box wing.svg
Box wing
Annular box wing.svg
Annular box wing
Annular cylindrical wing.svg
Cylindrical wing
Joined wing.svg
Joined wing
Wing annular flat.svg
Flat annular wing
Wing rhomboidal.svg
Rhomboidal wing

Wings can also be characterised as:

Rigid delta wing.svg
Rigid delta wing
Rogallo wing.svg
Flexible Rogallo wing

Planform

The wing planform is the silhouette of the wing when viewed from above or below.

See also variable geometry types which vary the wing planform during flight.

Aspect ratio

The aspect ratio is the span divided by the mean or average chord. [10] It is a measure of how long and slender the wing appears when seen from above or below.

Wing low aspect.svg
Low aspect ratio
Wing tapered.svg
Moderate aspect ratio
Wing high aspect.svg
High aspect ratio

Most variable geometry configurations vary the aspect ratio in some way, either deliberately or as a side effect.

Chord variation along span

The wing chord may be varied along the span of the wing, for both structural and aerodynamic reasons.

Wing constant.svg
Constant chord
Wing tapered.svg
Tapered (Trapezoidal)
Wing reverse tapered.svg
Reverse tapered
Wing compound tapered.svg
Compound tapered
Wing constant tapered outer.svg
Constant chord,
tapered outer
Wing elliptical.svg
Elliptical
Wing semi-elliptical.svg
Semi-elliptical
Wing birdlike.svg
Birdlike
Wing batlike.svg
Batlike
Wing circular.svg
Circular
Flying saucer.svg
Flying saucer
Wing annular flat.svg
Flat annular
Wing tailless delta.svg
Tailless delta
Wing delta.svg
Tailed delta
Wing cropped delta.svg
Cropped delta
Wing compound delta.svg
Compound delta
Wing ogival delta.svg
Ogival delta

Sweep

Wings may be swept back, or occasionally forwards, for a variety of reasons. A small degree of sweep is sometimes used to adjust the centre of lift when the wing cannot be attached in the ideal position for some reason, such as a pilot's visibility from the cockpit. Other uses are described below.

Some types of variable geometry vary the wing sweep during flight:

Wing tapered.svg
Straight
Wing swept.svg
Swept
Wing forward swept.svg
Forward swept
Wing variable sweep.svg
Variable sweep
(swing-wing)
Wing oblique.svg
Variable-geometry
oblique wing

Sweep variation along span

The angle of a swept wing may also be varied, or cranked, along the span:

Wing crescent.svg
Crescent
Wing cranked arrow.svg
Cranked arrow
Wing M.svg
M-wing
Wing W.svg
W-wing

Asymmetrical

On a few asymmetrical aircraft the left and right hand sides are not mirror-images of each other:

Wing asymmetric.svg Asymmetric torque.svg Wing oblique.svg
AsymmetricalTorque counteraction
by asymmetric span
Variable-geometry
oblique wing

Tailplanes and foreplanes

The classic aerofoil section wing is unstable in pitch, and requires some form of horizontal stabilizing surface. Also it cannot provide any significant pitch control, requiring a separate control surface (elevator) mounted elsewhere - usually on the horizontal stabilizer.

Wing swept.svg
Conventional tail
Wing canard.svg
Canard
Wing tandem.svg
Tandem
Wing tandem triple.svg
Three surface
Outboard tail.svg
Outboard tail
Wing tailless.svg
Tailless

Dihedral and anhedral

Angling the wings up or down spanwise from root to tip can help to resolve various design issues, such as stability and control in flight.

Some biplanes have different degrees of dihedral/anhedral on different wings. The Sopwith Camel had a flat upper wing and dihedral on the lower wing, while the Hanriot HD-1 had dihedral on the upper wing but none on the lower.

Monoplane dihedral.svg
Dihedral
 
Monoplane anhedral.svg
Anhedral
 
Biplane dihedral.svg
Biplane with dihedral
on both wings
Biplane lower dihedral.svg
Biplane with dihedral
on lower wing

In a cranked or polyhedral wing the dihedral angle varies along the span. (Note that the description "cranked" varies in usage. [24] [25] [26] [27] See also Cranked arrow planform.)

Monoplane gull.svg
Gull wing
Monoplane inverted gull.svg
Inverted gull wing
Monoplane cranked.svg
Dihedral tips
Monoplane cranked down.svg
Anhedral tips
Channel wing.svg
Channel wing

Wings vs. bodies

Some designs have no clear join between wing and fuselage, or body. This may be because one or other of these is missing, or because they merge into each other:

Wing flying.svg
Flying wing.svg
Flying wing
Wing blended.svg
Body blended.svg
Blended body
Wing lifting body.svg
Body lifting.svg
Lifting body

Some designs may fall into multiple categories depending on interpretation, for example many UAVs or drones can be seen either as a tailless blended wing-body or as a flying wing with a deep centre chord.

Variable geometry

A variable geometry aircraft is able to change its physical configuration during flight.

Some types of variable geometry craft transition between fixed wing and rotary wing configurations. For more about these hybrids, see powered lift.

Variable planform

Wing variable sweep.svg
Variable sweep
(swing-wing)
Wing oblique.svg
Variable-geometry
oblique wing
Wing telescopic.svg
Telescoping wing
 
Wing extending.svg
Extending wing
 
Folding wing.svg
Folding wing

Variable section

Variable incidence.svg
Variable incidence
wing
Variable camber.svg
Variable camber
aerofoil
Variable thickness.svg
Variable thickness
aerofoil

Polymorphism

A polymorphic wing is able to change the number of planes in flight. The Nikitin-Shevchenko IS "folding fighter" prototypes were able to morph between biplane and monoplane configurations after takeoff by folding the lower wing up into a cavity in the underside of the upper wing.

The slip wing is a variation on the polymorphic idea, in which a low-wing monoplane is fitted with a second detachable "slip" wing above it to assist takeoff. The upper wing is then released and discarded once in the air. The idea was first flown on the experimental Hillson Bi-mono.

Polymorphic wing.svg
Polymorphic wing
Slip wing.svg
Slip wing

Minor independent surfaces

Various minor surfaces Minorsurfaces annotated.svg
Various minor surfaces

Aircraft may have additional minor aerodynamic surfaces. Some of these are treated as part of the overall wing configuration:

Additional minor features

Additional minor features may be applied to an existing aerodynamic surface such as the main wing:

High lift

High-lift devices High-lift-devices annotated.svg
High-lift devices

High-lift devices maintain lift at low speeds and delay the stall to allow slower takeoff and landing speeds:

Spanwise flow control

Spanwise flow control device Spanwise-control annotated.svg
Spanwise flow control device

On a swept wing, air tends to flow sideways as well as backwards and reducing this can improve the efficiency of the wing:

Vortex creation

Vortex devices Vortex-devices annotated.svg
Vortex devices

Vortex devices maintain airflow at low speeds and delay the stall, by creating a vortex which re-energises the boundary layer close to the wing.

Drag reduction

Drag-reduction devices Drag-reduction annotated.svg
Drag-reduction devices

See also

References

Notes

  1. Taylor, J. (Ed.), Jayne's all the world's aircraft 1980–81, Jane's (1980)
  2. Green, W.; Warplanes of the second world war, Vol. 5, Flying boats, Macdonald (1962), p.131
  3. Taylor, 1990. p. 76
  4. Kroo, I. (2005), "Nonplanar Wing Concepts For Increased Aircraft Efficiency", VKI Lecture Series on Innovative Configurations and Advanced Concepts for Future Civil Aircraft June 6–10, 2005
  5. "Nonplanar Wings: Closed Systems". Aero.stanford.edu. Archived from the original on 11 August 2011. Retrieved 31 March 2012.
  6. Airliners.net, Lee Richards Annular, 2012, retrieved 31 March 2012
  7. 1 2 Henderson, William P. and Huffman, Jarrett K.; Aerodynamic characteristics of a tandem wing configuration of a Mach number of 0.30, NASA, October 1975.
  8. Marcel, Arthur; The Ligeti Stratos, ultralightaircraftaustralia.com, 2024. (retrieved 13 May 2022).
  9. Angelucco, E. and Matrciardi, P.; World Aircraft Origins-World War 1, Sampson Low, 1977
  10. Kermode (1972), Chapter 3, p. 103.
  11. Garrison, Peter (1 January 2003). "Rectangular Wings | Flying Magazine". Flyingmag.com. Archived from the original on 17 July 2022. Retrieved 17 July 2022. Bergey closes with the following advice: "When you walk past a Cherokee or an RV or any of the thousands of general aviation aircraft with Hershey Bar wings, flash them a friendly smile. Let them know you appreciate the high cruise efficiency of their almost ideal spanwise lift distributions. And their forgiving stall characteristics."
  12. Martin, Swayne (8 July 2016). "6 Wing Designs That Every Pilot Should Recognize". boldmethod.com. Archived from the original on 17 July 2022. Retrieved 17 July 2022. you can see how rectangular the Piper PA-23 Aztec's wing really is. There's a reason why they call it the "Hershey Bar" wing.
  13. Tom Benson; Wing Area, NASA
  14. Ilan Kroo. AA241 Aircraft Design: Synthesis and Analysis Wing Geometry Definitions, Archived 13 October 2015 at the Wayback Machine , Stanford University.
  15. G. Dimitriadis; Aircraft Design Lecture 2: Aerodynamics, Université de Liège.
  16. "Alexander de Seversky". centennialofflight.net. Retrieved 31 March 2012.
  17. Potts, J.R.; Disc-wing aerodynamics, University of Manchester, 2005.
  18. letter from Hall-Warren, N.; Flight International, 1962, p. 716.
  19. "swept wing | avro vulcan | 1953 | 0030 | Flight Archive". Flightglobal.com. 5 December 1952. Retrieved 29 May 2012.
  20. 1 2 Diederich and Foss; Static Aeroelastic Phenomena of M-, W- and Λ- wings, NACA 1953.
  21. "Aerodynamics at Teddington", Flight: 764, 5 June 1959
  22. 1 2 Ellis Katz; Edward T. Marley; William T. Pepper, NACA RM L50G31 (PDF), NACA, archived from the original (PDF) on 21 July 2011
  23. P180 Avanti-Specification and Description. See page 55, Appendix A: "Notes about the 3-Lifting-Surface design".
  24. Ernst-Heinrich Hirschel; Horst Prem; Gero Madelung (2004). Aeronautical research in Germany: from Lilienthal until today. Springer Science & Business Media. p. 167. ISBN   978-3-540-40645-7.
  25. Benoliel, Alexander M., Aerodynamic Pitch-up of Cranked Arrow Wings: Estimation, Trim, and Configuration Design, Virginia Polytechnic Institute & State University, May 1994, retrieved 31 March 2012
  26. "Boeing Sonic Cruiser ousts 747X". Flightglobal.com. 3 April 2001. Retrieved 31 March 2012.
  27. "WHAT IS IT? Aircraft Characteristics That Aid the Spotter Classified : A Simple Guide for Basic Features in Design the Beginner", Flight : 562, 4 June 1942
  28. "fs 29 - "TF"". Uni-stuttgart.de. 5 February 2012. Retrieved 31 March 2012.
  29. "Plane With Expanding Wing, Flies In Tests". Popular Science. November 1932. p. 31.
  30. Lukins, A.H.; The book of Westland aircraft, Aircraft (Technical) Publications Ltd, (1943 or 1944).
  31. Hearst Magazines (January 1931). "Adjustable Airplane's Wings Are Changed In Flight". Popular Mechanics. Hearst Magazines. p. 55.
  32. Flight, August 15, 1929
  33. Boyne, W.J.; The best of Wings magazine, Brassey's (2001)
  34. "FlexSys Inc.: Aerospace". Archived from the original on 16 June 2011. Retrieved 26 April 2011.
  35. Kota, Sridhar; Osborn, Russell; Ervin, Gregory; Maric, Dragan; Flick, Peter; Paul, Donald. "Mission Adaptive Compliant Wing – Design, Fabrication and Flight Test" (PDF). Ann Arbor, MI; Dayton, OH, U.S.A.: FlexSys Inc., Air Force Research Laboratory. Archived from the original (PDF) on 22 March 2012. Retrieved 26 April 2011.
  36. Calzada, Ruby (20 August 2015). "AFTI F-111". NASA. Retrieved 24 June 2020.
  37. 1 2 Wing vortex devices

Bibliography