This is where things begin to get complicated. If you imagine the way the accelerator, or gas pedal, works in your car it may become clearer. When you don't have your foot on the pedal (Collective lever all the way back) the engine will be at tick over. When you have your foot pressed all the way to the floor, (stick fully forward) you have full throttle. When you have your foot at the half way point you have half throttle.

What the Throttle Curve allows you to do is change the amount of throttle you have available at given points. Basic heli radios will have points set for low mid and high positions. More sophisticated radios have more pre set positions, for example low, quarter, half, three quarters and full.

If you want to fly inverted, you need to have power available as you increase the amount of negative pitch to keep the heli from ploughing into the ground. The way you can do this is to set the throttle curve so you have the right amount of power available to hover at half stick and full power available at full stick. But you also set the transmitter so the low throttle point also produces full power. This is sometimes referred to as a "V" shaped throttle curve.

Most pilots wanting to do aerobatics will set the helicopter so it hovers at the 75% stick position, not the usual 50%. It will also be set to hover inverted at the 25% position. That means there is little or no change in the power available between these two points. What WILL change between these two points is the amount and value of the pitch available. Throttle and pitch have a fundamental connection in the rotary world.

Pitch Curve.

Similar to the above, but the pre-set positions in your transmitter refer this time to the amount of pitch that's being applied to the main rotor blades.

The amount of pitch available on your helicopter, pitch range, is set mechanically. Most helicopters will hover at about 5 degrees positive pitch and be able to handle a maximum of about 10 degrees positive or negative. In practice, when the collective stick is all the way back you want a bit of negative pitch, about three degrees. This allows you to push the helicopter downwards when you bring the collective stick all the way back, especially if you've programmed the throttle to continue to produce power at bottom stick.

As an example, you might decide you want to increase the head speed to start aggressive aerobatics. You could do this by reducing the amount of pitch at the hover position, which will have the effect of reducing the lift available. To compensate for this, you would then increase the amount of power available at the hover point on the throttle curve, which would have the effect of increasing the rotor speed thus creating the additional lift needed.

Every helicopter is different so there are no hard and fast rules here. Providing you follow the manufacturers instructions in the helicopter kit, the mechanical set up should be pretty accurate. Kits often include reasonably detailed radio set up instructions so follow them to the letter and you should have a helicopter that at least will hover. The rest is all about fine-tuning which thankfully with modern computer radios is quick and convenient. Once you've been flying for a while, the instruction book that came with the radio will make more sense, and I hope these few pages on jargon will help as well.

Governor

A wonderful device that can make much of the above obsolete! A governor controls the speed of the motor to within a few RPM. The effect of this is that you achieve a constant head speed.

However, It will NOT compensate for a poor setup. Once you have achieved a constant head speed, flying becomes much smoother.

The governor compensates for additional loads imposed by control inputs such as right rudder, which in a normal setup will take power from the main rotor, therefore the heli will tend to drop. As the demand for power increases, the governor will open the throttle. You can program a governor to give different head speeds in each flight mode.

You MUST set up conventional throttle curves in your tranny, in case anything happens to the governor, but once set up, the collective stick just controls pitch.

The current hot favourites are the Throttle Jockey Pro and Futaba GV 1. Both achieve a similar result for differing costs!

There's a new breed of govenor available which are known as rev limiters. These are more sophisticated in their function and the overall effect is that the throttle response is sharper and more immediate. The current contendors are the RevMax and Revlok