Stall strips

A stall strip factory installed on an American Aviation AA-1 Yankee

A stall strip is a fixed device employed on the leading edge of fixed-wing aircraft to modify the aerodynamic characteristics of the airfoil.^[1] Stall strips are used to initiate flow separation at chosen locations on the wing during high-angle of attack flight, so as to improve the controllability of the aircraft when it enters stall. They are typically employed in pairs, symmetrically on both wings. On aircraft where wing airflow is affected by asymmetrical propeller wash, a strip may be used on a single wing to reduce risk of entering a spin.

Operation

The CL-215 features a stall strip on the right wing only, ensuring both wings stall at the same angle of attack despite the propeller wash.

A stall strip alters the wing’s stall characteristics and ensures that the wing root stalls before the wing tips. This is usually as a result of initial aircraft flight testing which shows that the existing stall characteristics are unacceptable for certification.^[1]

In some cases, such as the American Aviation AA-1 Yankee, stall strips are planned to be used on the wing from the start. In the case of the AA-1 the left and right wings were identical, interchangeable and built on a single wing jig, thus the more traditional use of washout in the wing design was not possible.

Stall strips typically consist of a small piece of material, usually aluminium, triangular in cross section and often 6-12 inches (15–30 cm) in length. It is riveted or bonded on the point of the wing’s leading edge, usually at the wing root. At high angles of attack, it trips the still-laminar boundary layer, initiating flow separation earlier than at other positions along the wing. This has the effect of causing the wing root to stall before the outer portions of the wing, ensuring a progressive outward stall, minimizing the risk of spinning and giving maximum aileron control throughout the stall.^[1]

They are usually factory-installed or, on rarer occasion, an after-market modification.

References

1 2 3 Crane, Dale: Dictionary of Aeronautical Terms, third edition, page 487. Aviation Supplies & Academics, 1997. ISBN 1-56027-287-2

Aircraft components and systems

Airframe structure	Aft pressure bulkhead Cabane strut Canopy Cruciform tail Dope Empennage Fabric covering Fairing Flying wires Former Fuselage Hardpoint Interplane strut Jury strut Leading edge Lift strut Longeron Nacelle Rib Ring tail Spar Stabilizer Stressed skin Strut T-tail Tailplane Trailing edge Triple tail Twin tail Vertical stabilizer V-tail Y-tail Wing root Wing tip Wingbox

Flight controls	Aileron Airbrake Artificial feel Autopilot Canard Centre stick Deceleron Dive brake Electro-hydraulic actuator Elevator Elevon Flaperon Flight control modes Fly-by-wire Gust lock Rudder 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 Blown flap Channel wing Dog-tooth Droop Flap Gouge flap Gurney flap Krueger flap Leading edge cuff LEX Slats Slot Stall strips Strake Variable-sweep wing Vortex generator Vortilon Wing fence Winglet

Avionic and flight instrument systems	ACAS Air data computer Airspeed indicator Altimeter Annunciator panel Attitude indicator Compass Course deviation indicator EFIS EICAS Flight data recorder Flight management system Glass cockpit GPS Heading indicator Horizontal situation indicator INS Pitot-static system Radar altimeter TCAS Transponder Turn and slip indicator Vertical Speed Indicator Yaw string

Propulsion controls, devices and fuel systems	Autothrottle Drop tank FADEC Fuel tank Gascolator Inlet cone Intake ramp NACA cowling Self-sealing fuel tank Splitter plate Throttle Thrust lever Thrust reversal Townend ring Wet wing

Landing and arresting gear	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 Entertainment system Environmental control system Hydraulic system Ice protection system Landing lights Navigation light Passenger service unit Ram air turbine Weeping wing

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Stall strips

Operation

See also

References