# Dronopter

So what’s a dronopter? It’s a drone that is a quadcopter. So what’s a drone? It’s a machine that flies via remote control without an on-board pilot. So what’s a quadcopter? It’s a helicopter with four motors. So what will you do in this simulation? You’ll design, build, and fly a dronopter to complete a mission. So get started.

### What is a force?

A force can simply be defined as any push or pull. However, a more in-depth definition can be applied to the phrase "net force." A net force is any push or pull that causes a change in the motion or shape of an object. If a car is standing still, a net force is needed to start the car moving. If the car's moving, a net force is required to slow it down, speed it up or to change its direction.

### How are forces measured?

Scientists generally use one of two measurement systems to measure forces. In the English system of measurement, force is measured in units of pounds, abbreviated as "lbs." However, most scientists in the world use the metric system of measurement. In this system, force is measured in a unit called the newton, abbreviated as "N." It's very important that you avoid confusing the terms mass, measured in grams or kilograms, with force. Mass is not a force, so therefore, grams or kilograms are never used as the units to measure force.

### What is a load?

In flight, a load is defined as any object that is being lifted up or supported in the air. If the object's motion is being changed, a net force is required to lift the load, while a steady force is needed to keep the load stationary in air against the force of gravity. For instance, if a piano is being lifted using a pulley system from the first floor up to the second floor, the piano is the load.

### What is thrust?

Thrust is the force that pushes an aircraft in the horizontal direction (usually forward, but a helicopter can thrust in the backwards direction). Thrust is accomplished by pushing air in the opposite direction the aircraft wants to move. The air is typically pushed backwards by a propeller or a jet engine. The air that's being pushed backwards produces an opposite reaction force back on the aircraft that causes the craft to move in the forward direction. Thrust is required to move the aircraft forward and must overcome the resistance of air called drag.

### What is lift?

Lift is the force that pushes an aircraft in the vertical direction. When lift is larger than the weight of the aircraft (including its load), the craft will change its vertical motion and move upward. When the weight of the aircraft is larger than the lift forces, the craft will move in the downward direction. The shape of aircraft's propeller blades give rise to lift through a combination of force and pressure differences.

### How does a helicopter fly?

While a typical fixed-wing aircraft has its propellers providing thrust and its wings giving the lift, a helicopter has its thrusting and lifting done with one device, its rotor, which is really a modified wing. This gives a helicopter the unique ability to move upward, downward, hover, move forward, move in the reverse direction, and spin about an axis. Most helicopters also have a tail rotor that helps to maintain stable flight and to keep the helicopter from spinning uncontrollably due to the torque created by the main rotor, which would cause the helicopter to spin in the opposite direction as the main rotor was spinning.

### What are the major parts of a quadcopter?

A quadcopter differs from a traditional helicopter in that it has four rotors instead of one main and one tail rotor. Each of the four motors with mounted rotors is placed on the end of four legs that extend from the main frame of the copter. The four motors must produce enough lift to counteract the weight of the quadcopter. The rotors must be arranged in a pattern that allows stable flight and keeps the quadcopter from spinning on its axis due to the torque created by the spinning rotors. Torque is a rotational force that causes circular or spinning motion.

### How are rotors different?

Rotors on a quadcopter provide both lift and thrust. Rotors can have different angles of blade pitch to give varying amounts of lift. Rotors also can spin in either clockwise or counterclockwise directions depending on the direction the motor spins that drives the rotor. Since a quadcopter does not have a tail rotor to counteract the spin of the main rotor, the arrangement of clockwise and counterclockwise rotor spins are critical to keep the quadcopter from spinning about its axis. If a quadcopter had four rotors all spinning in the same clockwise direction, the copter would spin uncontrollably about its axis in the counterclockwise direction.