Strake (aeronautics)

Short description: Flight control surface

Nose, wing and ventral strakes Vortices over the wing strakes of an F/A-18E Super Hornet

In aviation, a strake is an aerodynamic surface generally mounted on the fuselage of an aircraft to improve the flight characteristics either by controlling the airflow (acting as large vortex generators) or by a simple stabilising effect.

In general a strake is longer than it is wide, in contrast to a winglet or a moustache.

Leading edge root extensions (LERX) are also sometimes referred to as wing strakes.

## Contents

* 1 Nose strakes
* 2 Wing strakes
* 3 Nacelle strakes
* 4 Ventral strakes
* 5 Rear strakes—tail fins
* 5.1 Anti-spin strakes
* 6 Munitions
* 7 See also
* 8 References
* 9 External links

## Nose strakes

On both supersonic and subsonic types, smaller strakes are sometimes applied to the forward fuselage to control the fuselage flow at high angles of attack; for example, the Concorde had small nose strakes "to get a better directional stability".[1]

## Wing strakes

Further information: Leading edge root extension

Double delta wing aircraft (Concorde, Tupolev Tu-144, Boeing 2707 SST project) featured a forward extended leading edge that may be considered as a wing strake; it provides the same additional vortex lift at high angle of attack by leading edge suction.[2]

## Nacelle strakes

On jet aircraft where the engines are mounted in nacelles slung under the wings, strakes may be added to one or both sides of each nacelle to produce vortices that energize the airflow over the wings in times of high angle of attack, such as during takeoff and landing, thus improving wing effectiveness.

## Ventral strakes

Socata TB-200 ventral strakes

One or two ventral strakes are sometimes positioned under the fuselage, as large vortex generators, to provide a better tail surfaces efficiency. Typical examples can be seen on the SOCATA TB family or the Lockheed F-104 Starfighter.

## Rear strakes—tail fins

One or two large fins or strakes are sometimes positioned under the rear fuselage or below the empennage, to provide adequate stability at high angles of attack when the tail fin is shielded from the main airstream by the fuselage and/or the wing wake. Typical examples can be seen on the Piaggio P.180 Avanti, Learjet 60 and Beechcraft 1900D.

The Grumman X-29 research aircraft had rear fuselage lateral fins or "Tail fins",[3] sometimes called strakes,[4] continuous with the trailing edge of the main wing. This allowed the positioning of a rear control surface at the end of each fin. Together with the main and forward (canard) wing control surfaces, this effectively gave it a three-surface configuration.

### Anti-spin strakes

Spin strakes on DHC-1 Chipmunk

Anti-spin leading edge strakes, or spin strakes, or antispin fillet [5] may be placed at the tailplane roots of generally aerobatic aircraft, such as the de Havilland Tiger Moth (British version), Scottish Aviation Bulldog, and de Havilland Canada DHC-1 Chipmunk.[6] Ventral or dorsal fins increasing the directional stability are also used as anti-spin devices.

## Munitions

Certain air-deployed munitions, particularly "dumb" or unguided 500-pound (230 kg) bombs, are often retrofitted with bolt-on strake sets. Designed as an open collar with strakes fitted to the outside face, these strake sets are used to alter and normalize the aerodynamics of the weapon, yielding greater accuracy. As most such munitions were manufactured with only tail-mounted stabilizer fins, the addition of longitudinal strakes proves a much cleaner flow of air around the weapon during its glide, reducing the tendency to yaw and improving terminal accuracy.[citation needed]

Strakes are also often found on "smart" or guided munitions as an aid to the guidance system. By stabilizing the slipstream of air traveling over the weapon, the actions of control surfaces are much more predictable and precise, again improving the accuracy of the weapon.[citation needed]

## See also

* Chine (aeronautics)
* Leading edge extension
* Vortex generator

## References

1. ↑ André Peyrat-Armandy, Les avions de transport modernes et futurs, Teknea, 1997, p. 229
2. ↑ Hoerner, Fluid Dynamic Lift, Double Delta Wings
3. ↑ In Hoerner Fluid Dynamic Lift, "Tail fins - Dorsal and others fins on fuselage"
4. ↑ Miller, J.; The X-Planes, 2nd Printing, Speciality Press (1985)
5. ↑ Nasa TN D-6575, Summary of spin technology as related to the light general-aviation airplanes, fig. 10
6. ↑ Daroll Stinton, The design of the aeroplane, Lateral and directional stability and spinning, p.461.

## External links

* v
* t
* e

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 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|

* 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
* Flight recorder
* 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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