Aeromodelling Basics

Introduction to UAV

• Aeromodelling is the art of building and flying model aircrafts, which are small unmanned replicas of actual aircrafts.
• Model aircrafts are made for fun, static display, aerodynamic research, hobby, etc.

Classification of Aero Models

• There are two main types of models: static models and dynamic models.
• Static models are miniature replicas of original aircrafts, used for display purposes, and are not capable of flying.
• Dynamic models are capable of actual flight, considering factors such as weight, aerodynamic properties, balance, and strength.

Types of Aero Models

• Powered models use some source of power for facilitating their flight.
• Unpowered models, also known as gliders, do not have a power source for facilitating flight.
• R/C models (Radio Controlled) fly like real planes and are remote controlled.
• Control Line models are controlled from the ground by a pilot with the help of a tethered wing and a lightweight string.
• Rubber band powered models derive power from the unwinding of a twisted rubber band.
• Chuck gliders are launched by chucking or using a catapult, and tow-line gliders are taken to a certain altitude by another powered airplane and released.

Parts of an Airplane

• Fuselage: the body of an aircraft, supporting the wings and tail section, carrying payload, and is generally long and tubular in shape.
• Wings: lifting surfaces of an aircraft, housing control surfaces necessary for aircraft's maneuverability, shaped with smooth surfaces for laminar airflow.
• Tail/Empennage: providing stability to the aircraft, housing control surfaces for maneuverability, consisting of vertical and horizontal stabilizers.
• Engine/Power plant: providing thrust and power to the entire aircraft, with two main types: Turbo Prop (Propeller based) and Jet Engine.
• Landing Gear: the wheels of a plane, with brakes similar to car brakes, and most can be folded into the fuselage during flight and opened for landing.

Body Axes and Control Surfaces

• Axes of rotation: three axes of rotation, namely longitudinal, lateral, and vertical axes.
• Control surfaces: primary control surfaces consist of ailerons, elevators, and rudder, and secondary control surfaces consist of flaps, slats, and spoilers.
• Elevators: control pitch motion, longitudinal axis.
• Ailerons: control roll/bank motion, lateral axis.
• Rudder: control turn motion, vertical axis.
• Flaps and slats: vary lift coefficient, used to decrease lift-coefficient, increase drag, and assist in smoother landing.

Four Forces Acting on an Airplane

• Thrust: forward force of an airplane, produced by a propeller that takes power from the engines and displaces large mass of air to the rear.
• Drag: force resisting the forward motion of an airplane, consisting of induced drag and parasite drag, dependent on factors such as air viscosity, speed, wing area, airfoil shape, and angle of attack.
• Lift: upward force exerted on the wing due to the difference in air pressure above and below the wing, dependent on factors such as speed, wing area, angle of attack, and air density.
• Weight: the aircraft's gross weight, which decreases during flight due to fuel and oil consumption.

Bernoulli's Principle and Newton's 3rd Law

• Bernoulli's Principle: air moving over the wing moves faster than the air below, resulting in an upward push on the wing, causing lift.
• Newton's 3rd Law: to every action, there is an equal and opposite reaction, or the forces of two bodies on each other are always equal and are directed in opposite directions.

Flight Instruments

• Pitot-Static systems: measure airspeed and altitude.
• Speed indicators: air speed indicator (ASI), vertical speed indicator (VSI), altimeter, and Mach meter.
• Gyroscope: exhibits properties of rigidity and precision, used in instruments such as heading indicators and turn and bank indicators.
• Heading indicators: show the direction of the aircraft's nose.
• Turn and bank indicators: show the yaw and roll of an aircraft about vertical and longitudinal axes.
• Artificial horizon: gives instantaneous indication of slightest changes in attitude.
• Magnetic compass: the only direction-seeking equipment in an airplane, working on the principle of magnetism.
• Course deviation indicator: gives the aircraft's lateral position in relation to a track.

Materials Used in RC Modelling

• Balsa wood: fine straight grain material, creamy white in color, and light in weight, used to make propellers and wings of solid models.
• Ply wood: manufactured wood panel, used for panelling works, wing tips, and doublers.
• Bamboo: used to make undercarriages, tail and rudder frames, due to its strength, lightness, and flexibility.
• Pine, white wood, and mahogany: used to make propeller blades.