Indian Drone Pilot Course - Chapter 1, Lesson II

 

Indian Drone Pilot Course Guide Book

Chapter - 1: Ground Class Theory

Lesson II: BASIC PRINCIPLES OF FLIGHT

1. Fundamentals Of Flight

Airfoil: An airfoil (American English) or aerofoil (British English) is a streamlined shape, like a cross-section of a wing, designed to produce lift and drag when moved through the air.

Chord Line: The chord line in an airfoil is an imaginary straight line connecting the leading edge (front) and trailing edge (back) of the airfoil section.

Relative Wind: The relative wind is the direction of the wind in relation to the airfoil.

Angle of Attack: Angle of attack (AoA) is the angle between the chord line of an airfoil and the relative wind (or airflow) direction.

Angle of Incidence: Angle of Incidence (AoI) is the angle between the chord line of the airfoil and the longitudinal axis of the aircraft; it cannot be changed by the pilot.

Forces Acting on a Flight:

An aircraft in flight is influenced by four main forces:

1. Lift

   • Acts upward.

   • Generated by the wings due to the air pressure difference.

   • Opposes weight and keeps the aircraft in the air.

2. Weight (Gravity)

   • Acts downward.

   • Caused by the Earth's gravitational pull on the aircraft.

   • Opposes lift.

3. Thrust

   • Acts forward.

   • Produced by engines or propellers.

   • Propels the aircraft through the air.

4. Drag

   • Acts backward.

   • Caused by air resistance.

   • Opposes thrust and slows the aircraft down.

For stable, level flight, lift = weight and thrust = drag.

Principle Of Flight:

Coanda Effect: The Coanda Effect is the tendency of a fluid (air or liquid) to follow the contour of a nearby curved surface instead of continuing in a straight line.  

Key Points:  

- Discovered by Romanian aerodynamics pioneer Henri Coanda (1910).  

- Cause: The flow adheres to a curved surface due to fluid viscosity and pressure differences.  

- Applications in Aviation:  

  - Used in wing design to enhance lift (e.g., over the upper curved surface).  

  - Enables flaps and slats to improve control at low speeds.  

  - Used in thrust vectoring and some VTOL (Vertical Take-Off and Landing) aircraft.  

- Other Uses:  

  - Industrial fluid mixers, air conditioning systems, and hair dryers.  

The Coanda Effect helps improve aerodynamic efficiency by controlling airflow over surfaces.  

Bernoulli's Principle:

Bernoulli's principle states that as the speed of a fluid increases, its pressure decreases

In aviation, this principle helps explain how lift is generated on an aircraft wing:

• The upper surface of the wing is curved, causing air to move faster over it.

• The lower surface is flatter, so air moves slower underneath.

• Faster air on top creates lower pressure, and slower air below creates higher pressure.

• This pressure difference results in an upward lift force that helps the aircraft fly.

Newton's Laws of Motion:

• Newton's First Law: Any body continues to be at the state of rest or in continuous motion unless an external force is applied to it. For example, an airplane at rest on the ramp will remain at rest unless 2 force is applied, which is strong enough to overcome the airplane's inertia.

• Newton's Second Law: When a body is acted upon by a constant force, its resulting acceleration is inversely proportional to its mass. of the body and is directly proportional to the applied force. This law may be expressed by F=MA. For example, speeding up, slowing down, entering climbs or descents, and turning.

F=MA

 

• Newton's Third Law: For every action there is an equal and opposite reaction. This principle applies whenever two things act upon each other, such as the air and the propeller, or the air and the wing of an airplane.

(i)                    (ii)                    (iii)

Fundamentals Of Flight:

• Center of Lift: The average (mean) of the lift force through which all lift is considered to act, it's the same as the Center of Pressure.
• Center of Gravity: a point at which the aircraft would balance were it possible to suspend it at that point.                                                           Centre Of Lift

                                                       Centre Of Gravity

2. Aerodynamics

• Aerodynamics is the study of how air moves around objects. It is a branch of fluid dynamics and is crucial in the design of vehicles like airplanes, cars, and rockets to improve performance and fuel efficiency.
• Engineers apply the principles of aerodynamics to the designs of many different things, including buildings, bridges, etc.
• The primary concern of aerodynamics is aircraft and automobiles.
• Aerodynamics is involved in the study of flight and the science of building and operating an aircraft, which is called aeronautics.

Control Surfaces:

 Primary Control Surfaces of an Airplane are the main parts used by a pilot to control the aircraft’s movement in the air. These surfaces help maneuver the airplane along three axes: pitch, roll, and yaw.

1. Ailerons

   • Located on the trailing edges of the wings.

   • Control roll (tilting the wings side to side).

   • When one aileron goes up, the other goes down, causing the airplane to roll.

2. Elevator

   • Located on the tail (horizontal stabilizer).

   • Controls pitch (nose up or down movement).

   • Moving the elevator up makes the nose go up, and vice versa.

3. Rudder

   • Located on the vertical stabilizer (tail fin).

   • Controls yaw (nose left or right).

   • Helps in turning the airplane and maintaining balance during flight.

These control surfaces are essential for safe and precise flying, allowing the pilot to guide the plane smoothly through the air.

Axis Of Flight:

Axes of Flight refer to the three imaginary lines that pass through an aircraft and define its orientation and movement in the air. Each axis corresponds to a specific type of motion.

1. Longitudinal Axis (Roll Axis)

   • Runs from the nose to the tail of the aircraft.

   • Movement around this axis is called roll.

   • Controlled by the ailerons.

   • 
     
     

     
     

2. Lateral Axis (Pitch Axis)

   • Runs from wingtip to wingtip.

   • Movement around this axis is called pitch.

   • Controlled by the elevator.

   • 
     
     

     
     

3. Vertical Axis (Yaw Axis)

   • Runs vertically through the center of the aircraft.

   • Movement around this axis is called yaw.

   • Controlled by the rudder.

   • 

 Axis

Takeoff, Flight, and Landing

• Takeoff:
  Takeoff is the phase where an aircraft leaves the ground and begins to ascend. It typically starts with the aircraft accelerating along the runway until it reaches the necessary speed to lift into the air, aided by the wings generating enough lift.

• Flight:
  Flight refers to the period when the aircraft is airborne and moving toward its destination. During this phase, pilots maintain altitude, speed, and direction, adjusting for weather and air traffic. It involves cruising at high altitudes and sometimes climbing or descending as needed.

• Landing:
  Landing is the final phase where the aircraft returns to the ground. Pilots carefully lower the altitude, align with the runway, and slow down the plane for a smooth touchdown, eventually braking to a full stop.

Maneuvers, Turns, and Circuit Pattern

• Maneuvers:
  Maneuvers are controlled movements an aircraft performs to change its flight path, speed, or altitude. They include climbs, descents, turns, and more complex actions like stalls and recoveries, used for training, navigation, or aerobatics.

• Turns:
  Turns are maneuvers where the aircraft changes direction by banking its wings. The pilot adjusts the ailerons and rudder to maintain a smooth, coordinated curve without losing altitude.

• Circuit Pattern:
  A circuit pattern (or traffic pattern) is a standard path aircraft follow around an airport when taking off or landing. It usually includes legs like upwind, crosswind, downwind, base, and final, ensuring safe and organized traffic flow.

                                                                                                                Ready for take-off.........

To read Chapter 1, Lesson III, click here

Chapters II & III will be updated shortly.