Learning

In the UAV world there a number of active propulsion types - electric motor, internal combustion (IC), and rubber band. The rubber band method is often used to power free flight planes. Members often fly these type of planes indoors. Electric motors and internal combustion engines, would be common in RC UAV's - and these are the types you would most commonly see outdoors. 

 1. Internal Combustion

Most people will be familiar with internal combustion from driving cars, or taking the train or bus to work. Internal combustion engines for UAV's run in the exact same way - they burn a fuel such as methanol, petrol or diesel, and produce a force that can turn a propeller, or even a miniature turbine blade.

2. Electric Motor

Electric motors have existed for many decades, but they have not been strongly associated with the hobby until relatively recently. The main reason, is that battery technologies had not been developed or were prohibitively expensive. These days however, the cost of the batteries, and also the electronics has dropped dramatically. As a result, many UAV pilots have opted for electric motors rather than internal combustion.

3. Rubber Band (Click Here)

Rubber band power is a very old method. It's very simply a band of rubber or elastic material - one end attached to a fixing, and the other to the blade rotor. They can be would by hand, or in case of the larger planes - a winder. The method is most common with free flight, but it can also be used with a RC system.

UAV's are broadly split into three common types - fixed wing, helicopters and quadcopters. There are variations on these, such as tri-copters, but we won't be going into that much detail. Each of them work on the same principle, as in they rely on an aero foil that can generate lift.

1. Fixed Wing

A fixed wing, is a static piece of aero-foil, that allows for flight. It may have moving surfaces attached such as ailerons, flaps and flaperons to maneuver during flight. This type of aero-foil is very widely used in commercial, and hobbyist aviation. For the novice pilot, we would recommend a UAV with this type of aero-foil.

2. Helicopters

Helicopters rely on a whirling or spinning wings, moving around a central point. Like a fixed wing, the profile of the blades allow for lift. However since the blades are spinning, they generate torque in the direction the blades spin. To counteract this, many helicopters have a long boom extending to the rear with a tail rotor. The tail rotor has a blade attached that exerts force in the opposite direction to prevent the entire helicopter from spinning uncontrollably. Varying the pitch of the blades on the main, and the tail rotor, allows the aircraft to be maneuvered.

3. Quadcopters

When we hear the word, "drone", or news about drones, we will think of something with four sets of blades, that can move in various directions. These are in fact, "quadcopters", and are the UAV's at people tend to associate with. They do have a similarity to helicopters, as they have rotating aero-foils that generate lift. The directional torque is opposed by spinning the rotors that are diagonally opposite each other, in the opposite direction. Generally speaking, the up and down movement is controlled by increasing the rotational speed of the rotors simultaneously. The remaining movements are controlled by varying the speeds of the rotors independently.

There are two main types of control systems you will see nowadays - radio control and control line.

1.Radio Control

This is  a system that allows for an electromagnetic signal to be received, that signal to be interpreted, and in a UAV that signal to be converted to movement of control surfaces such as ailerons on a plane, or blades on a helicopter. The system comprises of a number of components.

• Transmitter (generates a signal and transmits)

• Aerial (picks up the signal and relays it)

• Receiver (receives the relayed signal)

• Servo motors (follow the direction of the signal, and produce movement)

• Battery packs (one to power the transmitter, and one or more to power the receiver, and servos)

2.Control Line

Control line was one of the first methods of flying model planes. There is usually one or more lines of stainless steel wire or low stretch monofilament  attached to a bell-crank in the model, and a special handle the pilot holds in his hand. Attached to the bell-crank there are pushrods which are attached to linkages on the control surfaces. Taking hold of the handle (thumb up), and tilting the hand moves the bell crank in one direction or the other.