In my previous blog I presented some pitch angles that are a good place to start for doing autorotations. However, if you are in the process of learning to hover it’s important to reduce the collective pitch range to keep the helicopter from being too sensitive. Many helicopter setup instructions recommend 5 to 10° of negative pitch and about 10° of positive pitch. Unfortunately, this makes the helicopter very sensitive to hover and gives you the capability to either descent or climb very rapidly, neither of which is very desirable in the learning process. I therefore recommend you adjust the total collective pitch movement from 0° as a minimum to 4° as a maximum. This does several good things:
1. The 4 degrees should be just enough to get the helicopter with training gear off the ground, but yet not let it get too high where it could be in danger. This is also a good way to judge your rotor rpm. If it takes much more than 4° to get airborne then the rotor speed is probably too slow, which will desensitize both aileron and elevator control.
2. The minimum of 0° pitch will let the helicopter descend, but not quickly enough where it could damage itself from a reasonable altitude. At this stage of your training altitude is your friend, but having the capability to descend too rapidly can cause more harm than good.
3. The other added benefit from this collective pitch range is the collective stick will be less sensitive, and therefore easier for you to control. To hover the helicopter the collective will need to be close to its maximum position, and then the helicopter will barely get off the ground. When a descent is required it will only take a small decrease in collective to let the helicopter gently descend as required. This also has the added benefit of keeping the engine at, or close to, full power to provide the lift necessary for both the helicopter and the added weight of the training gear.
Follow the collective setup procedures in your building instructions, but make all adjustments with the minimum possible throw since a total collective range of 0° to 4°is all that will be required.
Nice article Paul. The first liftoffs are scary enough without setting up 3D rates.
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