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The DC 10 also uses a fore and trailing flap combination.
Here the flap assembly is hinged externally and the fore flap is attached to the trailing flap through a rail. As hydraulic actuators pivot the fore flap in the hinge, the fore flap extends along the rail and forms a slot.
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On the Boeing 707 fore- and trailing flaps are one unit with a fixed slot.
The flap assembly extends along a curved rail.
The lower flap shroud on the wing is hinged and moves upward to improve the airflow through the slot during flap extension.
The Cessna, as an example of a small aircraft, uses a dual roller system on the single flap support arm.
These two rollers follow individual slots in a guide rail.
The upper and lower slots are initially parallel which allows aft movement of the flap.
Towards the last third of the travel the upper slot is curved down and the lower curved up which deflects the flap downwards.
Flight Controls
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A single, cockpit-operated, electric motor drives a single screw jack connected to control rods. A cable circuit assures symmetrical operation on both wings.
"Slats and leading edge flaps"
A wind tunnel experiment shows us the need for high lift devices on the leading edge. Smoke is used to visualise the airflow over a flat plate.
Using a bend in the plate to simulate flap deflection the smoke trail is deflected downwards.
As a result of the so-called pre-orientation of flow the airflow ahead of the plate is also deflected downwards. This increases the angle of attack and especially on fast airfoils with a small nose radius can lead to an early stall. To reduce this effect leading edge flaps or slats are commonly used.
Flap 0°
Forward roller
Aft roller FLAP
Control cables
Control rods
Fowler Flaps
Flap select lever
Electric Motor Screwjack
CESSNA
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"Leading edge flaps"
Leading edge flaps fold down when the trailing flaps are lowered.
The drooped leading edge is hinged at the bottom and when extended maintains a smooth surface on top of the wing.
The Kruger flap is a hinged panel hinged slightly aft of the leading edge.
During extension an additional hinged portion folds out and forms a new leading edge.
Both types of leading edge flaps actively increase the camber of the wing. Both devices can be operated by hydraulic actuators or mechanical screw jacks.
SMOKE TRAIL
SMOKE JET
MARKER
PLATE SMOKE TRAIL
SMOKE JET
MARKER
PLATE
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"Slats"
The Slat forms the leading edge of the wing when retracted.
When it is extended the slat increases the camber of the wing and forms a slot that directs high-energy air over the top surface of the wing to prevent stalling of the airflow at high angles of attack.
Slats can be mechanically or hydraulically operated.
On some fighter airplanes and small airplanes the operation of the slats is automatic as a result of aerodynamic forces.
Flight Controls
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"Flap system of the Dash 8"
The wing flap system consists of two segments on each wing.
The flap selector transfers the input via a cable circuit, to the flap power unit.
The flap power unit is powered by the number 1 hydraulic system and operates the flaps via a flap drive system.
A flap setting of 5°, 10°, 15° and 35° is available on the Dash 8-300.
The wing flap system consists of a drive system, a control system, and four flap sections.
The inboard flap is located between the fuselage and the nacelle.
The outboard flap is located between the nacelle and the aileron.
The flap position can be seen on the flap position indicator on the co pilots panel.
35°
15°
10°
5°
0°
F L A P S
FLAP DEG
0 5 15
20
35
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The flap control system is operated by the flap selector.
The detente cam provides settings from 0 degree in the full forward position, via 5, 10, and 15 degrees to 35 degrees in the full aft position.
To change the flap setting, the trigger must be pulled, to lift the cam follower.
At the next position the trigger must be released.
The cam follower will engage in this position.
The Quadrant transmits the movement via a cable circuit to the hydraulic flap power unit.
The cable circuit is routed from the cockpit under-floor, up behind the copilot to the ceiling. and in the ceiling backwards to the center wing area, up to the flap power unit.
Flight Controls
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The flap drive system consists of the flap power unit, the primary drive system and the secondary drive system.
Four ball screw actuators in each wing drive the flaps.
One transfer gearbox on each side, connects the secondary drive to the primary.
The torque sensor unit will illuminate a caution light, if the secondary drive is used.
Five flap tracks, on each wing support the flaps.
COUPLING TORQUE
Flight Controls
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"Dash 8 Spoiler control system"
The roll spoilers augment the ailerons in providing lateral control.
They are hinged to the trailing edge of the wing.
The spoilers extend 75°upwards when fully deflected.
The system is hydraulically operated by the number 1 system for the inboard spoilers, and the nr. 2 system for the outboard spoilers.
The spoilers rise in parallel with the up-going aileron.
At speeds above 140 knots only the inboard spoilers operate.
The spoilers are controlled from the pilot's control column.
Rotary movement of the pilot's control wheel is transmitted by a chain and sprocket mechanism to a lever on the base of the column.
The lever is connected to the spoiler quadrant via a push rod.
The quadrant integrates a tension regulator.
The tension of the roll spoiler cable to the splitter quadrant is maintained constant under all
temperature conditions by the tension regulator.
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"Ground spoilers and speed brake system of the Embraer 145"
The outboard surfaces provide the speed brake and ground spoiler functions, while the inboard surfaces provide only the ground spoiler function.
The spoiler surfaces are made of composite material, and the subsystem is hydraulically actuated and electrically controlled.
The control of the ground spoiler function is automatic during the landing and rejected take off.
The speed brake function is controlled by the pilot.
The operation of the ground spoiler is automatic during the landing and rejected takeoff procedures.
With the aircraft on ground, the ground spoiler logic receives the first signal from the landing gear proximity switches.
When the wheel speed gets up to 25 knots of the turning speed, the speed sensor sends the second signal.
When the pilot moves the two thrust levers to below 30°, the spoiler control unit will operate the spoiler surfaces to open.
CHECK
GO AROUND GO AROUND
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The indications of the spoilers on the EICAS display are:
To operate the speed brake, the aircraft must have engine thrust lever angles below 50°, flaps set to 0°and the airspeed below 202 knots IAS.
In these conditions, when the pilot operates the speed brake lever, the spoiler control unit commands the outboard spoiler surfaces to open.
If one of these conditions does not occur, and the pilot operates the speed brake lever, the EICAS display will show the caution message SPEED BRAKE LEVER DISAGREE and the surfaces remain closed.
0
The spoiler OPEN or CLOSED indicating the surfaces condition.
The SPOILER FAIL indicates a failure found in the spoiler control unit.
There is also an aural warning message TAKE OFF SPOILER when the pilot tries a takeoff with the spoiler surface open
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"Dash 8 Trim control systems"
A trim tap is hinged on the inboard trailing edge of the right aileron.
The trim tap is electrically operated and controlled by the trim switch.
The actuator is installed in the aileron and connected to the trim tap by an adjustable push rod.
A position potentiometer sends a signal to the indicator next to the switch.
Pressing LEFT WING DOWN releases the internal magnetic brake and extends the actuator. When the switch is released to neutral, the magnetic brake operates, arresting the actuator movement. Pressing right wing down retracts the actuator.
LWD RWD AIL TRIM
L NOSER
RUDDER TRIM
RUDDER AILERON
L W D
R W D
TRIM
R L
+
TRIM TAB RIGHT AILERON
Flight Controls
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A trim tab is mounted on the outboard trailing edge of each elevator.
The trim tab is operated manually from the trim hand-wheel, on the center consol.
The movement is transmitted via chains to the cable circuit in the under-floor compartment, to the tail cone.
Up in the vertically stabilizer, to the horizontal stabilizer.
The trim actuator converts the rotary movement of the cable in a linear movement, to adjust the trim tab.
Elevator trim indication is accomplished mechanically. A spiral on the inside face of the pilots hand-wheel converts rotary movement to linear movement of the pointer.
Elevator Trim Tab System
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A standby elevator trim system is provided. In the event of a trim cable fracture forward of servo, electrical trim can be accomplished.
The servo of the auto flight control system is used for this feature.
Selecting the guarded switch on the pilot's side panel arms the system.
Now either control switch on the co-pilots or pilot's side can be used to activate the trim. BETA BACKUP TEST P/L SW 1 P/L SW 2
STDBY ELEVATOR TRIM NOSE DOWN