In most modern helicopters there is an electronic governor that monitors the rotor RPM and adjusts the engine power as required. So when the collective is raised, the pilot needs to open the throttle to produce more engine power in order to prevent the rotor blades from slowing down. However, increasing the lift also means that there is more drag. And as with any aircraft, when the lift is greater than weight the helicopter will take off – or in this case, lift into hover. The pilot does this by using the collective or lever on his left side, which ‘collectively’ alters the pitch of the blades. The magnitude of TRT is changed by increasing or decreasing the pitch angle of the rotor blades, and thereby their angle of attack. The direction and magnitude of this can be altered in order to control the helicopter. In the case of a helicopter, this is usually known as total rotor thrust (TRT). When the rotor blades start to spin, the air flowing over them produces lift, just as when the wings of an airplane start to move. The crucial difference in helicopters is that the airflow is produced by rotating the ‘wings’ rather than by moving the whole aircraft. This means that each blade is an aerofoil that, when placed in an airflow, deflects the air in order to produce lift. The rotor blades of a helicopter are identical to the wings of an airplane. So let’s take a look at how it all works… The Basic Principles Of How Helicopters Fly While a helicopter is a far more complex machine than an airplane, the fundamental principles of flight are the same, and understanding the basics really isn’t all that difficult. After all, it’s incredibly complicated, isn’t it?Īctually, the principles of helicopter flight are really not all that difficult to understand. In their view, dental treatment without an anesthetic might be preferable to trying to learn about this stuff. How does this bunch of noisy, whirling, vibrating parts manage to hurl itself into the air, never mind fly under any semblance of control? They reckon that a helicopter is like a bumblebee – it shouldn’t be able to fly, but nobody told the bumblebee. Others – many pilots among them – find helicopter aerodynamics not only a complete mystery but one they would rather leave well alone. Many people think it is a complete mystery that helicopters manage to fly at all.
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