Wing twist is an

aerodynamic Aerodynamics, from grc, ἀήρ ''aero'' (air) + grc, δυναμική (dynamics), is the study of the motion of air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dyn ...

feature added to

aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...

wing A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoils. A wing's aerodynamic efficiency is expres ...

s to adjust lift distribution along the wing. Often, the purpose of lift redistribution is to ensure that the wing tip is the last part of the wing surface to stall, for example when executing a

roll Roll or Rolls may refer to: Movement about the longitudinal axis * Roll angle (or roll rotation), one of the 3 angular degrees of freedom of any stiff body (for example a vehicle), describing motion about the longitudinal axis ** Roll (aviation), ...

or steep climb; it involves twisting the wingtip a small amount downwards in relation to the rest of the wing. This ensures that the effective

angle of attack In fluid dynamics, angle of attack (AOA, α, or \alpha) is the angle between a reference line on a body (often the chord line of an airfoil) and the vector representing the relative motion between the body and the fluid through which it is m ...

is always lower at the wingtip than at the root, meaning the root will stall before the tip. This is desirable because the aircraft's

flight control surfaces Aircraft flight control surfaces are aerodynamic devices allowing a pilot to adjust and control the aircraft's flight attitude. Development of an effective set of flight control surfaces was a critical advance in the development of aircraft. Ea ...

are often located at the wingtip, and the variable stall characteristics of a twisted wing alert the pilot to the advancing stall while still allowing the control surfaces to remain effective, meaning the pilot can usually prevent the aircraft from stalling fully before control is completely lost. Twist that decreases the local chord's incidence from root to tip is sometimes referred to as '' washout''. Twist that increases the local incidence from root to tip is less common and is called ''wash-in''. The

Grumman X-29 The Grumman X-29 was an American experimental aircraft that tested a forward-swept wing, canard control surfaces, and other novel aircraft technologies. The X-29 was developed by Grumman, and the two built were flown by NASA and the United St ...

had strong wash-in to compensate for the additional root-first stalling promoted by the forward sweep. Wing twist can also, rarely, refer to the deflection of the wing when it is made of insufficiently stiff materials; actuation of the flaps can, instead of deflecting air as intended, cause the wing itself to be deflected and is related to compressibility effects; this problem has mostly been eradicated however, with modern high-strength

alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...

s and composites. Wing twist is also observed in

insects Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of j ...

References

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External links

Aerospaceweb- Wing Twist and Dihedral F-18 Hornet & Super Hornet Wing Twist
* ttp://thefullgull.com/the-sutter-twist/ The Sutter twist – an engineering storya wing twist named after the "father of the 747"

Joe Sutter Joseph Frederick Sutter (March 21, 1921 – August 30, 2016) was an American engineer for the Boeing Airplane Company and manager of the design team for the Boeing 747 under Malcolm T. Stamper, the head of the 747 project. ''Air & Space/Smit ...

Aerodynamics Aircraft wing design

See also

References

External links