Primary Controls
Created | Updated Apr 16, 2003
In a flight simulator, as in an aircraft, the primary controls are responsible for controlling flight of the machine. These controls differ depending on the type of aircraft—fixed-wing aeroplanes or helicopters1.
Helicopters
Helicopter primary controls are three in number, controlling the main horizontal rotor immediately above the fuselage and the vertical rotor in the tail:
- Cyclic
- Collective
- Anti-torque
Cyclic and collective controls affect the forces exerted by the main rotor. Anti-torque pedals are connected to the tail rotor. Each of these controls has a different, critical effect.
Cyclic
Cyclic control is provided via a joystick that adjusts the individual pitch of each blade of the main rotor as it revolves. Blade pitch changes depending on its angular position in the cycle. As pitch changes so does the amount of lift generated by the blade. Net result of this variation in pitch of the rotor blades is different amounts of lift at different positions within the disc of rotation. When the cyclic control is centred, the rotor blades are set to produce the same lift everywhere in the disc of rotation, hence lifting the helicopter vertically into a hover. When hovering you can think of the centre of lift somewhere immediately above the helicopter.
Position of the centre of lift is controlled by the cyclic2.
Now, when the cyclic is moved away from its neutral position the position of the centre of lift is changed to drag the helicopter in that direction. If it moves forward of the centre of gravity then the helicopter moves forward; if it moves aft of the centre of gravity then the helicopter moves aft; and so the helicopter is dragged in the direction of the centre of lift, wherever that may be in relation to the helicopter's centre of gravity.
Flying an helicopter is like trying to maintain your vertical balance on the head of a pin, it requires continual small adjustments of the cyclic control by the pilot who must coordinate these movements with the collective, anti-torque pedals, and throttle3.
Collective
Instead of adjusting the pitch of individual rotor blades, the collective control makes the same pitch adjustment to all blades collectively. In effect the collective is course adjustment of pitch to all blades whereas the cyclic is a fine pitch adjustment to individual blades.
By increasing the pitch of the rotor blades and the power from the engine, the overall lift is increased to raise the helicopter into the air. The collective control is a large lever in the floor at the side of the seat to the pilot's left hand. A twist grip is incorporated into the handle to provide throttle control of the engine.
Anti-torque Pedals
One of Newton's Laws of Motion states that for every action there is an equal and opposite reaction. Helicopters obey this law. With large diameter, rapidly rotating blades attached to the top of the helicopter, the fuselage will tend to spin in opposite direction to the blades as soon as the undercarriage is free of the ground. To prevent this dizziness helicopters are equipped with vertical tail rotors to counteract the torque produced by the main rotor. Because the torque of the main rotor varies so must the counteracting force of the tail rotor.
Variation in tail rotor force is controlled through the anti-torque pedals, which increase or decrease the pitch of the tail rotor blades. An added benefit is that the torque-pedals provide horizontal directional control to allow the helicopter to point in any direction.
Aeroplanes
Aeroplanes have fixed wings, unlike helicopters of course. Like helicopters, their primary controls are three in number:
- Elevator
- Aileron
- Rudder
This is true unless the aeroplane happens to be delta-winged like the British Vulcan Bomber, the British-French Concorde, or the American Space Shuttle, more of which later.
Elevator
An elevator is a hinged, trailing edge section of the horizontal stabilizer in the tail of the aircraft; it is attached to the joystick or control column in the cockpit, moving up or down in response to the pilot pulling aft or pushing forward the joystick or control column. Elevators control movement of the aeroplane about its lateral axis that passes from left to right through the center of gravity.
When the pilot pulls back on the stick, the elevator moves upward into the slipstream4 which has the effect of pushing the tail down and nose up; as long as there is enough power available from the engines, the aircraft will climb through the air. Conversely, if the pilot pushes forward on the stick then the elevator will move downwards into the slipstream increasing the lift on the tail, hence lifting the tail and pitching the nose downwards, causing the aircraft to descend.
Aileron
Ailerons are small, hinged sections in the trailing edges of the mainplanes or wings of an aeroplane. Controlled by lateral movement of the joystick or turning action of the control wheel, the ailerons move in opposite direction to each other.
When the stick is moved to the left, the left aileron moves up into the slipstream as the right aileron moves down. Effect of this is to push the left wing down and the right wing up, rotating the aeroplane about its longitudinal axis running fore and aft through the centre of gravity.
Rudder
Rudder of an aeroplane is a large hinged section in the trailing edge of the vertical stabiliser of the tail. It is connected to the rudder pedals in the cockpit. Motion of the rudder pedals are in opposition to each other via mechanical linkage. When the pilot pushes on the left rudder pedal it moves forward as the right moves aft; in so doing, the rudder moves left into the slipstream to push the tail of the aircraft to the right and the nose left about the vertical axis of the aeroplane.
Delta-winged Aeroplanes
Delta-winged aeroplanes have their elevators and ailerons combined into elevons on the trailing edges of the delta-wing. Reason for this is that delta-winged aircraft have no horizontal stabiliser in the tail, the delta-wing serves the purpose, extending as it often does all the way back along the fuselage. Elevons combine both the symmetric movement of elevators and asymmetric movement of ailerons.