Ex. 4 Effects of Controls

It is assumed that the helicopter has an anti-clockwise blade rotation when viewed from above. This table describes the function of the flight controls.
During the demonstrations it should be noted that only one control is displaced at a time, in a very deliberate attempt to show the effect of that control in isolation, this is not how we would normally fly the helicopter.

Control	Movement	Primary Effects	Secondary Effects
Cyclic	Fore	Nose Pitches Down Airspeed Increases	Descent Left Yaw
	Aft	Nose Pitches Up Airspeed Decreases	Climb Right Yaw
	Left	Roll Left Left Turn, Heading Decreases
	Right	Roll Right Right Turn, Heading Increases
Collective	Up	Torque Increase Climb	Nose Pitch Up Airspeed Decrease
	Down	Torque Decrease Descent	Nose Pitch Down Airspeed Increase
Throttle	Open	RPM Increase	Climb Right Yaw
	Closed	RPM Decrease	Descent Left Yaw
Pedals	Left	Left Yaw	RPM Decrease
	Right	Right Yaw	RPM Increase

RRPM will increase due to a rotor drag decrease with an increase in speed.
Extremes of speed can be detected by an increase in noise and vibration as well as being indicated on the airspeed indicator.

Torque is the turning force applied by the engine to the transmission system.
When the torque supplied is equal to the torque demanded by the transmission the RRPM will remain the same.
Increasing the blade pitch angle will result in more lift and more drag being produced by the blades. This will result in an increase in Rotor Thrust and an increase in Torque.
We effect a torque change by raising or lowering the lever.
The manufacturers know that more power will be demanded from the engine and usually install components to assist the pilot in meeting this requirement as the torque demand is increased. These components will take the form of engine RPM governors, or throttle correlators.
A governor will maintain RPM by measuring RPM (sometimes indirectly) and making adjustments to the fuel supplied to then engine to maintain RPM.
A Correlator does not sense engine RPM and mechanically alters the throttle setting to allow 'about the right amount' of fuel to be fed to the engine as a result of the increased demand.

Yaw in forward flight is inefficient, as the airflow over the airframe is not taking the easiest route past it (more drag).
Most helicopters suffer from some form of inherent sideslip, which means that in the cruise they can either be flown in balance (ball centered) or wings level, but not both at the same time. This sideslip is a result of a number of factors including tail rotor position, main rotor rotation, center of gravity position.

Disc Loading is an apparent increase in the weight of the aircraft supported by the rotor disc . This can be felt in the 'seat of the pants' as you are pushed harder into your seat. The Rotor RPM will be seen to increase with an increase in disc loading, due to an increase in coning angle producing what is known as 'The Coriolis Effect'. In a Flare the airflow from below the disc reduces the induced flow, tilting the total reaction forwards and increasing RPM.

Selecting hydraulics on will reduce the forces required to move the flight controls.
Selecting hydraulics off, or loss of hydraulic control due to a system failure will result in an increase in control forces and on some aircraft a noticable coupling between flight controls.

The control frictions are used to hold the flight controls in a fixed position during startup and shutdown, freeing the pilots hands for any necessary actions required during these phases of flight.
It is normal for some Collective friction to be applied in flight, although this is a personal preference of the pilot and is not mandatory. Collective friction would be used in flight to hold a power setting and prevent the lever from moving of its own accord.
The use if cyclic friction is not usually required and expressly forbidden in some aircraft flight manuals.
Not all helicopters are fitted with a trim system. The trim system is used to reduce the cyclic feedback forces and to hold in any force necessary to keep the cyclic in a selected position. The trimmer is usually activated by the use of a 'coolie hat' on the top of the cyclic.

The function of the flight instruments will become clearer over the course of the next few lessons, however it is normal to point out the primary instruments during this exercise. The most useful instruments in this exercise are

• The Airspeed Indicator
• The Altimeter
• The VSI
• The Heading Indicator, or the Compass
• The Manifold Pressure Gauge (if a piston)

If the aircraft is a turbine the

• N₁ Gauge
• The Torque Gauge
• The T.O.T. Gauge

There is no requirement at this stage to examine the instruments in detail, although they will reinforce what can be clearly seen out of the window during the demonstrations.

Piston engine aircraft which are not fuel injected suffer from a problem known as carburettor icing. This is alleviated by the use of carburettor heat, this is used in two ways the first is to prevent the formation of any ice, and the second which is quite literally to melt any ice which may have formed in the carburettor. It is normal for the RPM to falter if ice is being melted and drawn into the engine, the caburettor heat should remain selected even if this does happen.
Turbine engines are prone to ice forming on the inlet guide vanes which is alleviated by feeding some warm air to the vanes from a hotter section of the engine.
Any form of engine inlet heating has a performance penalty because the air allowed into the engine is less dense by virtue of the fact it has been heated.