AEROMODELLING WORKSHOP

What is Aeromodelling? Aeromodelling is the art of designing, building and flying miniaturized aircrafts (powered or non-powered). It is both a hobby and sport; the hobby aspect involves building and assembling model aircraft, and the sport part involves the flying.

Model airplanes are sized down models of an aircraft The calculations are easy and importance is given to building of the plane

What is this Workshop about? Did you always want to get into the aviation industry? Have you ever dreamt of becoming an Aeronautical Engineer? Ever wondered how it feels to design your own aircraft and see it soar into the sky? Then Take a Break and come to Jet wings RC Aircraft Workshop.

WHY ? This workshop by Jet wings gives you an opportunity to understand the theory behind the functioning of aircraft and aircraft design. It makes you innovate by coming up with your own design of an RC aircraft and fabricate it from scratch. An interactive lecture session and design session helps you design the best performing aircraft.

Basic Aerodynamics

Forces acting on a plane

LIFT It’s the upward force acting on the planes due to the air flow over the wings It is determined by the design of the wing and the wind nature as L=1/2ρV2ACL CL is the lift coefficient V is flight speed, A is wing area ρ is density of air

THRUST It’s the force provided by the engine of the plane Mainly two type of thrust generators are used IC Engines Electric Motors We will be seeing about electric motors here

WEIGHT This is the weight of the plane along with its payload and motors. This should be minimized as much as possible by proper design.

DRAG This is the weight of the plane along with its payload and motors. This should be minimized as much as possible by proper design.

Difference between aircraft and airplane? An aircraft is any machine that can fly.  Airplanes, hot air balloons, helicopters, or even flying platforms are considered aircraft. An airplane is a specific type of aircraft that has fixed wings and engine, it is heavier than air that is capable of sustained, powered, and controlled flight.

What is an RC aircraft or RC plane? A remote-controlled aircraft is a small flying machine that is controlled remotely by an operator on the ground using a hand-held radio transmitter

Materials used for RC aircrafts Balsa Styrofoam Depron Coroplast

Balsa This wood is very light and can easily work for almost every purpose in aeromodelling. It can be drawn in sheets of even 1mm thickness.

Styrofoam This material is light as well as strong. It is a kind of expanded polystyrene used especially for making RC aircraft structure.

Depron It is a closed cell Styrofoam foam in sheet form. It is a fantastic medium for building model aircraft. It is extremely lightweight.

Coroplast Coroplast is simply the two sheets of plastic separated by another layer of zigzagged plastic. It is lightweight, inexpensive, and fairly sturdy.

COMPONENTS

Electrical components Brushless motor Servos motor Transmitter Receiver Electronic speed controller LI Po Battery.

Brush-Less DC motor (BLDC) A Brush-Less DC motor (BLDC) is a synchronous electric motor which is powered by direct-current electricity (DC) . Which has an electronically controlled commutation system, instead of a mechanical commutation system based on brushes. In such motors, current and torque, voltage and rpm are linearly related.

Internal BLDC Motor Contraction

servo motor A Servo is a small device that has an output shaft. This shaft can be positioned to specific angular positions by sending the servo a coded signal. As long as the coded signal exists on the input line, the servo will maintain the angular position of the shaft. As the coded signal changes, the angular position of the shaft changes.

Transmitter A transmitter is an electronic device which, usually with the aid of an antenna, propagates an electromagnetic signal such as radio, television, or other telecommunications. When talking about RC transmitter modes we are referring to how the transmitter is set up to control the airplane which sticks operate which controls on the model.

Receiver It consists of receiver module and a antennae wire of about 2-3 feet long. The receiver gets signal from the transmitter and then acts upon the servos Nowadays there are ECSs which have separate power for the receiver so there is no need for separate power.

Lithium polymer batteries Li-poly batteries are also gaining favor in the world of Radio-controlled aircraft as well as Radio-controlled cars where the advantages of both lower weight and greatly increased run times can be sufficient justification for the price. However ,lithium polymer-specific chargers are required to avoid fire and explosion.

WING ASPECTS

Wings and Aerofoil The lift generation is decided by the shape of the wings and the aerofoil The lifting force is provided by the difference in the pressure of air flowing below and above the wing and is governed by Bernoulli’s principle

How do you design a good wing? By proper calculation of the wingspan , wing loading and aspect ratios By making a good aerofoil By optimizing the angle of attack to have good lift to drag ratios

Angle of Attack (aoa) This is the relative angle made by the wind with the wings

Relation between aoa & lift Angle of attack is directly proportional to the lift coefficient till a maximum limit which is generally about 17o After which the plane stalls

CONTROL SURFACES

These are the surfaces which divert the direction of wind to provide change in direction of flight There are basically three types of rotation of plane which provide the change in direction

Rotation of a plane

DESIGN PRINCIPLES

Wing Loading It is the ratio of the weight of the plane to the wing area Gives a measure of the load given per unit area of the wing Wing loading is an important factor which decides the balance between the forces

Aspect Ratio(AR) Aspect Ratio is the ratio of square of wingspan to the area of the wing AR = l2 / A Where ‘l’ is the wingspan and A is the area of wing Typical aspect ratios for gliders are 6-8

POWERING THE PLANE

Motor Thrust ECS Battery Propellers

Motor specifications After the thrust required is calculated the configuration of the motor is decided The motor is selected by its KV rating which is basically the RPM per volt it can deliver The KV rating is calculated by max current so while selecting a battery and ECS see to it that continuous current rating is greater than motor rating.

Typical motors One of the usually motors used is the 2204 motor which provides about 350 gms of thrust The thrust provided also depends upon the propellers used which is again specified by its pitch and diameter length.