Droop (aeronautics)

"Droop nose" redirects here. For the drooping nose on supersonic aircraft, see droop-nose.

Airbus A380 approaching to land, with deployed droops visible between the fuselage and the inner engines

A droop or droop nose is a type of high-lift device found on the wings of some aircraft. Droops are similar to leading-edge slats, but with the difference that the entire leading edge section rotates downwards, whereas a slat is a panel that moves away from a wing leading edge when it is deployed.^[1]

Location

Droops are a type of leading edge device, mounted as they are on the rounded front part of a wing. The Airbus A380 has a droop between the fuselage and each inboard engine, at the leading edge of the thickest part of each wing.^[1]^[2] Early variants of the Hawker Siddeley Trident had two droops on the outboard of each wing and a Krueger flap on the section closest to the fuselage.^[3]

Use and effect

Droops function with other high-lift devices on an aircraft to increase the camber of the wing and reduce the stalling speed. On the Airbus A380, the first stage of lift device selection deploys the droops (called droop noses by Airbus) and leading-edge slats located further out on the wing; with the flaps starting to extend when the second stage is selected. The droops on the A380 may be deployed to a position 22 or 25 degrees lower than their stowed position.^[2] Another function of the droops on the A380 is to change the stall characteristics of the wing.^[4] The A380's designers found that the airflow between the engines was separating from the wing surface prior to the airflow between the engine and the fuselage, an undesirable characteristic. Adding a droop between the engine and the fuselage fixed the problem; whereas using a leading-edge slat would not have done so because of the gap (or slot) created between a slat and the wing when a slat is deployed.^[4]

Aircraft fitted with droops

References

Notes

1 2 Norris & Wagner (2005), pp.67-68
1 2 Norris & Wagner (2005), p.155
↑ Flight International 29 June 1972, p.933 retrieved 7 March 2014
1 2 Norris & Wagner (2005), p.67

Bibliography

"Inquiry briefing". Flight International (London: IPC Business Press) 101 (3303): 932a–934. 29 June 1972. |access-date= requires |url= (help)
Norris, Guy; Wagner, Mark (2005). Airbus A380: Superjumbo of the 21st Century. St. Paul, Minnesota: Zenith Press. ISBN 0-7603-2218-X. |access-date= requires |url= (help)

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 Spar Stabilizer Stressed skin Strut T-tail Tailplane Trailing edge Twin tail Vertical stabilizer V-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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