Leading-edge extension

A leading-edge extension (LEX) is a small extension to an aircraft wing surface, forward of the leading edge. The primary reason for adding an extension is to improve the airflow at high angles of attack and low airspeeds, to improve handling and delay the stall. A dog tooth can also improve airflow and reduce drag at higher speeds.

Leading-edge slat

Airbus A318-100

A

stall, allowing the aircraft to fly at a higher angle of attack. Slats may be made fixed, or retractable in normal flight to minimize drag

.

Dogtooth extension

A dogtooth is a small, sharp zig-zag break in the leading edge of a wing. It is usually used on a swept wing, to generate a

drooped leading edge arrangement.^{[citation needed}

]

Many high-performance aircraft use the dogtooth design, which induces a vortex over the wing to control boundary layer spanwise extension, increasing lift and improving resistance to stall. Some of the best-known uses of the dogtooth are in the stabilizer of the

Quest Kodiak

, the dogtooth is created by adding an extension to the outer section of the leading edge.

Leading-edge cuff

American Aviation AA-1 Yankee

A leading edge cuff (or wing cuff) is a fixed aerodynamic device employed on fixed-wing aircraft to introduce a sharp discontinuity in the leading edge of the wing in the same way as a dogtooth. It also typically has a slightly drooped leading edge to improve low-speed characteristics.

Leading-edge root extension

A leading-edge root extension (LERX) is a small fillet, typically roughly triangular in shape, running forward from the leading edge of the wing root to a point along the fuselage. These are often called simply leading-edge extensions (LEX), although they are not the only kind. To avoid ambiguity, this article uses the term LERX.

On a modern

stall

point at which the airflow separates from the wing surface, thus sustaining lift at very high angles.

LERX were first used on the

Cobra Turn and the Kulbit

.

A long, narrow sideways extension to the fuselage, attached in this position, is an example of a

chine

.

Leading-edge vortex controller

Leading-edge vortex controller (LEVCON) systems are a continuation of leading-edge root extension (LERX) technology, but with actuation that allows the leading edge vortices to be modified without adjusting the aircraft's attitude.[4] Otherwise they operate on the same principles as the LERX system to create lift augmenting leading edge vortices during high angle of attack flight.

This system has been incorporated in the Russian Sukhoi Su-57 and Indian HAL LCA Navy.^[5]

The LEVCONs actuation ability also improves its performance over the LERX system in other areas. When combined with the

Pugachev's Cobra.^{[dubious – discuss]}^{[citation needed]} Additionally, on the Sukhoi Su-57 the LEVCON system is used for increased departure-resistance

in the event of TVC failure at a post-stall attitude. It can also be used for trimming the aircraft, and optimizing the lift to drag ratio during cruise.

References

^ Effects of Wing-Leading-Edge Modifications on a Full-Scale, Low-Wing General Aviation Airplane, Nasa TP 2011
^ A Two-seat Gnat Development for the R.A.F. Flight 1959
^ Green, W. and Swanborough, G.; The complete book of fighters, Salamander, 1994
^ Lee, Gwo-Bin. "Leading-edge Vortices Control on a Delta Wing by Micromachined Sensors and Actuators" (PDF). American Institute of Aeronautics and Astronautics. Retrieved 18 October 2018.
^ Sweetman, Bill. "Sukhoi T-50 Shows Flight-Control Innovations". Aviation Week. Aviation Week & Space Technology. Retrieved 18 October 2018.

[1] Effects of Wing-Leading-Edge Modifications on a Full-Scale, Low-Wing General Aviation Airplane, Nasa TP 2011

[2] A Two-seat Gnat Development for the R.A.F. Flight 1959

[3] Green, W. and Swanborough, G.; The complete book of fighters, Salamander, 1994

[4] Lee, Gwo-Bin. "Leading-edge Vortices Control on a Delta Wing by Micromachined Sensors and Actuators" (PDF). American Institute of Aeronautics and Astronautics. Retrieved 18 October 2018.

[5] Sweetman, Bill. "Sukhoi T-50 Shows Flight-Control Innovations". Aviation Week. Aviation Week & Space Technology. Retrieved 18 October 2018.

[5]

v t e Aircraft components and systems
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Flight controls	Aileron Airbrake Artificial feel Autopilot Canard Centre stick Deceleron Dive brake Dual control Electro-hydraulic actuator Elevator Elevon Flaperon Flight control modes Fly-by-wire Gust lock HOTAS Rudder Rudder pedals Servo tab Side-stick Spoiler Spoileron Stabilator Stick pusher Stick shaker Trim tab Wing warping Yaw damper Yoke
Aerodynamic and high-lift devices	Active Aeroelastic Wing Adaptive compliant wing Anti-shock body Blown flap Channel wing Dog-tooth Drag-reducing aerospike Flap Gouge flap Gurney flap Krueger flap Leading-edge cuff Leading-edge droop flap LEX Slats Slot Stall strips Strake Variable-sweep wing Vortex generator Vortilon Wing fence Winglet
Avionic and flight instrument systems	ACAS Air data boom Air data computer Aircraft periscope Airspeed indicator Altimeter Annunciator panel Astrodome Attitude indicator Compass Course deviation indicator EFIS EICAS Flight management system Glass cockpit GPS Head-up display Heading indicator Horizontal situation indicator INS ISIS Multi-function display Pitot–static system Radar altimeter TCAS Transponder Turn and slip indicator Variometer Yaw string
Propulsion controls, devices and fuel systems	Autothrottle Drop tank FADEC Fuel tank Gascolator Inlet cone Intake ramp NACA cowling NACA duct Self-sealing fuel tank Splitter plate Throttle Thrust lever Thrust reversal Townend ring War emergency power Wet wing
Landing and arresting gear	Aircraft tire Arrestor hook Autobrake Conventional landing gear Drogue parachute Landing gear Landing gear extender Oleo strut Tricycle landing gear Tundra tire
Escape systems	Ejection seat Escape crew capsule
Other systems	Aircraft lavatory Auxiliary power unit Bleed air system Deicing boot Emergency oxygen system Environmental control system Flight recorder Hydraulic system Ice protection system In-flight entertainment system Landing lights Navigation light Passenger service unit Ram air turbine