地面扰流板系统

概述

The ground spoiler system comprises the full-span deployment of wing upper-surface spoiler panels immediately upon touchdown, serving the dual purpose of destroying residual wing lift and increasing aerodynamic drag during the landing roll. Their deployment is a critical contribution to stopping performance: by rapidly reducing wing lift to near-zero, ground spoilers transfer the full aircraft weight onto the landing gear wheels within seconds of touchdown, maximising the normal load available for wheel braking friction. A wing that retains significant lift after touchdown places only a fraction of aircraft weight on the wheels, substantially reducing available brake force.

Ground spoilers are distinct from the flight spoiler/speedbrake panels — though they share the same physical surfaces. In flight, only a subset of spoiler panels deploy as speedbrakes; on the ground, all available panels deploy simultaneously and to their maximum travel. The combined effect of full-span deployment at low altitudes can temporarily create a large nose-down pitching moment, which is why deployment is inhibited in the air and interlocked with the weight-on-wheels system.

工作原理

During approach, the crew arms the ground spoiler system by setting the speedbrake lever to the ARMED position. This arms an automatic deployment logic that continuously monitors weight-on-wheels, throttle position, and wheel spin-up signals. On touchdown, when the weight-on-wheels signal confirms ground contact and/or wheel spin-up is detected above a threshold RPM, the spoiler control computer commands all spoiler panels to the fully extended position (typically 45–60° from the wing surface). Deployment is hydraulically actuated and occurs within approximately one second of touchdown.

On some aircraft, spoiler deployment logic requires corroborating inputs from multiple sensors to prevent inadvertent deployment in flight — for example, the Boeing 737 requires both weight-on-wheels confirmation and throttle-at-idle before auto-spoiler deploys. This belt-and-suspenders approach ensures a go-around (with throttles advanced) would not inadvertently deploy ground spoilers even if a spurious WOW signal occurred.

If the auto-deployment logic fails, the crew can manually deploy spoilers by pulling the speedbrake lever fully aft after touchdown, achieving the same aerodynamic effect. Ground spoilers retract automatically when the crew advances thrust for a touch-and-go or when a go-around is initiated.

关键组件

• Spoiler Panels: Hinged upper-surface panels spanning most of the wing area aft of the front spar. Constructed of carbon-fibre composite or aluminium alloy. The number of active panels varies by aircraft — the A320 uses five panels per wing, the 777 uses seven.
• Hydraulic Actuators: One per panel, converting hydraulic pressure into rotational motion at the panel hinge. Must respond rapidly (full deployment in <1 second) and be capable of overcoming aerodynamic hinge moments at landing speeds.
• Spoiler Control Computer (or equivalent): Digital controller managing the arm/deploy/retract logic, integrating WOW signals, throttle resolver inputs, wheel speed signals, and speedbrake lever position.
• Speedbrake/Ground Spoiler Lever: Cockpit lever with detents for RETRACTED, ARMED (for auto-deploy on landing), and manual positions up to FULL SPEEDBRAKE. Arming the lever before landing is a standard descent checklist item.
• Proximity Switches on Panels: Position sensors confirming each panel's deployed and retracted status, feeding cockpit spoiler indication.

飞机应用

• Boeing 737-800 — six spoiler panels per wing; auto-deploy on WOW + throttle at idle; contribute approximately 15–20 percent of landing distance improvement versus no spoilers
• Airbus A320-200 — five spoilers per wing; SFCC (Spoiler and Flap Control Computer) manages deployment; ground spoilers deploy at 72° deflection
• Boeing 777-300ER — seven spoiler panels per wing; large surface area critical given the high lift generated by the wide wing; complex sequencing with autothrottle disengagement
• Boeing 787-9 — composite spoiler panels; auto-deploy logic integrated with brake-by-wire ground mode for coordinated deceleration

优势与局限

Ground spoilers can reduce landing distance by 15–25 percent compared to braking alone, primarily through the rapid weight transfer to the wheels rather than through aerodynamic drag alone (though drag contribution is also meaningful, particularly at higher landing speeds). They also reduce brake temperatures by allowing braking to begin at higher effectiveness earlier in the roll. Full-span deployment is visually dramatic — from inside the cabin, passengers see and hear the panels deploy — and the associated pitching moment can be felt as a nose-down bump, but these are normal and expected.

The principal risk is inadvertent in-flight deployment. Ground spoiler deployment at altitude would cause immediate, violent pitch-down and roll, loss of lift, and structural loading potentially exceeding design limits. The multi-sensor interlock logic (WOW plus throttle state plus wheel spin-up) is designed to make this event essentially impossible under any credible single-failure scenario. The system's failure to deploy after touchdown — due to a failure to arm, a logic fault, or a WOW sensor issue — results in longer stopping distances and is treated as a performance-limiting condition requiring increased runway length margins.