Vortilons are fixed
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 ...
devices on aircraft wings used to improve handling at low speeds.
The vortilon was invented by aerodynamicists working at
Douglas Aircraft
The Douglas Aircraft Company was an American aerospace manufacturer based in Southern California. It was founded in 1921 by Donald Wills Douglas Sr. and later merged with McDonnell Aircraft in 1967 to form McDonnell Douglas; it then operated as ...
who had previously developed the engine pylons for the
Douglas DC-8
The Douglas DC-8 (sometimes McDonnell Douglas DC-8) is a long-range narrow-body airliner built by the American Douglas Aircraft Company.
After losing the May 1954 US Air Force tanker competition to the Boeing KC-135, Douglas announced in July ...
. The original pylons which wrapped around the leading edge of the wing had to be cut back to reduce excessive cruise drag. Wind tunnel testing of the next Douglas commercial aircraft, the
Douglas DC-9
The McDonnell Douglas DC-9 is an American five-abreast single-aisle aircraft designed by the Douglas Aircraft Company. It was initially produced by the developer company as the Douglas DC-9 until August 1967 and then by McDonnell Douglas.
After ...
which had no under-wing engines, showed a cutback engine pylon would be beneficial to wing lift and upwash at the tail at the low speed stall. The pylon was reduced in size and became the vortilon (VORTex-generating-pYLON).
Vortilons consist of one or more flat plates attached to the underside of the
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 ...
near its leading edge, aligned with the flight direction.
When the speed is reduced and the aircraft approaches
stall, the local flow at the leading edge is diverted outwards; this spanwise component of velocity around the vortilon creates a
vortex
In fluid dynamics, a vortex ( : vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in th ...
streamed around the top surface, which energises the
boundary layer
In physics and fluid mechanics, a boundary layer is the thin layer of fluid in the immediate vicinity of a bounding surface formed by the fluid flowing along the surface. The fluid's interaction with the wall induces a no-slip boundary cond ...
.
A more turbulent boundary layer, in turn, delays the local flow separation.
Vortilons are often used to improve low-speed
aileron performance,
thereby increasing resistance to
spin. They can be used as an alternative to
wing fences, which also restrict airflow along the span of the wing.
Vortilons only stream vortices at high
angles 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 ...
and produce less drag at higher speeds than wing fences.
Pylons used to mount
jet engine
A jet engine is a type of reaction engine discharging a fast-moving jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include rocket, Pump-jet, water jet, and hybrid propulsion, the term ...
s under the wing produce a similar effect.
The occurrence of span-wise flow at high angles of attack, such as observed on
swept wings, is an essential requirement for vortilons to become effective. According to
Burt Rutan
Elbert Leander "Burt" Rutan (; born June 17, 1943) is a retired American aerospace engineer and entrepreneur noted for his originality in designing light, strong, unusual-looking, and energy-efficient air and space craft. He designed the recor ...
, vortilons installed on straight wings would not have any effect.
Vortilons were first introduced with the
McDonnell Douglas DC-9
The McDonnell Douglas DC-9 is an American five-abreast single-aisle aircraft designed by the Douglas Aircraft Company. It was initially produced by the developer company as the Douglas DC-9 until August 1967 and then by McDonnell Douglas.
Afte ...
to achieve a strong nose down pitching moment just beyond the normal stall and their influence ceased to have any effect beyond 30 degrees angle of attack.
They have been used on subsequent aircraft, including:
*
McDonnell Douglas MD-80
The McDonnell Douglas MD-80 is a series of five-abreast single-aisle airliners developed by McDonnell Douglas. It was produced by the developer company until August 1997 and then by Boeing Commercial Airplanes. The MD-80 was the second gene ...
*
McDonnell Douglas MD-90
The McDonnell Douglas (later Boeing) MD-90 is an American five-abreast single-aisle airliner developed by McDonnell Douglas from its successful model MD-80. The airliner was produced by the developer company until 1997 and then by Boeing Comme ...
*
Boeing 717
The Boeing 717 is an American five-abreast single-aisle airliner produced by Boeing Commercial Airplanes. The twin-engine airliner was developed for the 100-seat market and originally marketed by McDonnell Douglas as the MD-95. It was a shor ...
*
Rutan VariEze
The Rutan VariEze is a composite, canard aircraft designed by Burt Rutan. It is a high-performance homebuilt aircraft, hundreds of which have been constructed. The design later evolved into the Long-EZ and other, larger cabin canard aircraf ...
, replacing
leading edge cuff
A leading-edge cuff is a fixed aerodynamics, aerodynamic wing device employed on fixed-wing aircraft to improve the Stall (flight), stall and spin (aerodynamics), spin characteristics. Cuffs may be either factory-designed or an after-market add- ...
s (1984)
*
Rutan Long-EZ
The Rutan Model 61 Long-EZ is a tandem 2-seater homebuilt aircraft designed by Burt Rutan's Rutan Aircraft Factory. The Long-EZ has a canard layout, a swept wing with wingtip rudders, and a pusher engine and propeller. The tricycle landing ...
*
BAe 125
The British Aerospace 125 is a twinjet mid-size business jet. Originally developed by de Havilland and initially designated as the DH.125 Jet Dragon, it entered production as the Hawker Siddeley HS.125, which was the designation used until 19 ...
1000 series
*
Hawker 800XP
*
Embraer ERJ 145 family
The Embraer ERJ family (for Embraer Regional Jet, model names EMB-135, EMB-140 and EMB-145) are regional jets designed and produced by the Brazilian aerospace company Embraer. The family includes the ERJ135 (37 passengers), ERJ140 (44 passeng ...
*
Learjet 45
The Learjet 45 (LJ45) aircraft is a mid-size business jet aircraft produced by the Learjet Division of Bombardier Aerospace.
The Model 45 was the first all-new design since the original Learjet, and significantly altered the Learjet line. Throug ...
*
Aériane Swift
The Aériane Swift is a lightweight (48 kg) foot-launched tailless aircraft, tailless sailplane whose rigid wings have a span of 40 feet. The Swift has been succeeded by the "Swift'Lite".
Although designed in California, Swift aircraft are n ...
*Experimental
Vought F-8 Crusader
The Vought F-8 Crusader (originally F8U) is a single-engine, supersonic, carrier-based air superiority jet aircraft built by Vought for the United States Navy and United States Marine Corps (replacing the Vought F7U Cutlass), and for the Fren ...
with supercritical wing. The supercritical wing would have been prone to pitch-up as the wing had increased sweep and aspect ratio compared to the standard wing. No pitch-up problems were experienced with vortilons fitted.
[https://www.nasa.gov/centers/dryden/pdf/88410main_H-1957V1.pdf,p.87 ]
See also
*
Vortex generator
A vortex generator (VG) is an aerodynamic device, consisting of a small vane usually attached to a lifting surface (or airfoil, such as an aircraft wing) or a rotor blade of a wind turbine.
*
Wing fence
References
External links
Wing Vortex Devicesfrom Aerospaceweb.org explains vortilons and other vortex-generating wing appliances
{{Aircraft components
Aircraft wing components