Now you've read the introduction, you should be motivated enough to head for the hobby shop straight away. But before you do, let's first look at how aircraft fly and the characteristics of a model aircraft so you can understand what you should be looking for when you buy your first kit. Then we'll look at the types of models that are suitable for beginners to build and fly.

How do aircraft fly?

As you probably already know, it's the wing that is responsible for keeping a plane in the air. To see how this works, let's take a look at the wing's cross-sectional shape, called an aerofoil. In the diagram opposite, you'll see that as air moves over the wing, the air flowing above the wing must travel faster to reach the trailing edge at the same time as the air flowing underneath the wing.

An aerofoil showing lift and drag.

This creates an area of lower pressure above the wing, in effect sucking the wing upwards. This is called lift, and an aeroplane will not leave the ground until the wing is generating enough lift to overcome its weight. Of course, in the normal run of things, air will not conveniently pass over the wing. So we have to arrange the next best thing - for the wing to move through the air. We can do this in two ways: by fitting a motor (an electric one, of course!) to our model to provide thrust, or by launching it by some method. There is a natural resistance to any forward movement through air. This is called drag. Drag is caused by the shape of the aircraft, skin friction and the process of creating lift. The aircraft will only move forwards when the thrust generated by the motor is enough to overcome the drag generated by the model.

These four forces dictate whether an aircraft will fly or not. In order to fly, the aircraft must be able to generate enough thrust to get the plane to a speed where the lift generated by the wing is enough to overcome the aircraft's weight. If these four forces exactly cancelled each other out, the model would fly straight and level with no change in airspeed or altitude.

Aircraft Characteristics

Wing placement
Wing placement falls into three categories: high wing, mid wing and low wing. In a high wing design, the weight of the model is suspended below the wing, so that its weight always tries to return it to a level position, making it more stable and easier to fly. That's why trainers, like the Electri-Cub shown opposite, are all high wing designs. Low-wing models, on the other hand, are less stable and are therefore better suited to advanced flyers who want to perform rolls, loops and other aerobatic manoevers.
Aerofoil
Aerofoils also fall into three categories: flat-bottomed, symmetrical and semi-symmetrical. Flat-bottomed aerofoils develop the most lift at lower speeds, so they are the best choice when you're learning to fly. The thickness of the aerofoil determines how much drag is created. A thick wing creates more drag, resulting in slower speeds and gentler stalls.
Dihedral
Dihedral is the upward angle of the wings from the fuselage. Dihedral increases stability and decreases aerobatic ability. Trainers have a relatively large dihedral angle, and this is sometimes increased (especially in gliders) by using polyhedral (a second upward bend in the wings).

Types of Models Suitable for Beginners
Your first model should have high-wing placement, a flat-bottom aerofoil and generous dihedral. These types of model are gentle, slow-flying craft that offer more reaction time, and feature "self-righting" characteristics that return them to straight and level flight just by releasing the controls. Some are offered as ARF (Almost Ready to Fly) kits which require minimal building time.

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