Fixed and rotary wing aircraft

Fixed and rotary wing aircraft, for all their differences are actually very similar in how they actually fly. To a lay person, not grounded in the theory of aviation looking at two examples of the different types can lead them to think that they operate in two very different ways. If we look at two good examples of both fixed and rotary wing aircraft we can see how this confusion might occur. Take a small fixed wing aircraft like a Cessna for example. Most people have seen these flying out of small aerodromes and the principle of how it lifts into the air seems pretty obvious; it moves forward and the air gets under the wing to push it up.

Obviously it is a bit more complicated than that. The aerofoil section of the wing meaning that air passing over the curved upper section has to travel faster than that traveling along the flatter underside. The air traveling faster creates a low pressure zone on top of the wing; the high pressure zone in effect pushes the wing up.

In essence the layman observer is right; if it were to stop moving forward then it would fall out of the sky. Contrast this with the rotary wing aircraft, the obvious example of which is the helicopter. This is much harder to understand at first glance. What is it doing? It’s not moving forward yet it is rising into the sky? It seems to be screwing itself upwards in some way?

Again not far off, but not totally accurate either. The helicopter in our example does indeed have wings like in our Cessna but these wings are very thin and there are more of them. They are the helicopters rotor blades. Instead of moving the plane through the air to generate lift, the helicopters ‘wings’ are moved through the air to generate lift. The body of the craft can remain relatively static such as when it hovers.

Fixed and rotary wing aircraft may look different and operate and sound different, but underneath it all they are relying on the same basic principles to stay in the air.