Aerodynamics Questions

rc2017's version from 2017-09-05 19:25


Question Answer
Newtons lawsa. First – Every object exits in its state of rest or in uniform motion in a straight line unless external forces act upon it

b. Second – For a constant mass, force equals mass times acceleration.

c. Third – For every action, there is an equal and opposite reaction.
4 forces acting on aircraftLift, thrust, drag and weight, T = D, W = L .....till plane moves forward, Newtons first law of motion
What is thrust?Thrust is the forward force produced by the power plant / propeller / rotor. It opposes or overcomes the force of drag
What is Drag?Drag – the resistance experienced by the aircraft when passing through air. It opposes thrust & acts parallel to relative wind
Total Drag?Total drag is induced drag + parasite drag.
Induced DragThe drag which is component of Lift is called induced drag. it is maximum at slow speed
Parasite DragThe parasite drag is made up of interference, form and surface friction
What is Lift?Lift is the component at right angle or perpendicular to relative airflow. Lift opposes the downward force of weight & is produced by the dynamic effect of air acting on the airfoil. Lift acts from Centre of Pressure
What is Weight?Weight is the combined load of the aircraft which pulls the aircraft downward because of the force of gravity. It opposes lift. Weight acts from Centre of Gravity
AerofoilAerofoil is a surface capable of producing aerodynamic reaction from oncoming airflow (lift/thrust/weight/drag). It can be dissected into - Leading edge and trailing edge, upper camber, lower camber, chord line,
What is camber line?Camber line is a line that can be drawn equidistance from upper and lower surface of aerofoil (upper and lower camber)
What is chord line?Chord Line is the line that can be joined from the center of leading edge and center of trailing edge
Separation pointPoint where airflow breaks away from aerofoil (Stall scenario)
Angle of Attack?Angle of attack – The angle between cord line and relative airflow. Critical angle of attack is the angle beyond which you will stall – 15 to 17 deg because the lift is maximum.
Angle of Incidence?Angle of Incidence is the Angle between a line parallel to the longitudinal axis of the plane & the Chord Line
What is center of gravity?Centre of Gravity is the mass center of the airplane or the point at which the entire weight of the airplane is assumed to be concentrated
What is center of PressureCentre of Pressure is a point along the wing chord line where lift is considered to be concentrated. It is also referred to as Centre of lift.
What is a camber?Camber is the basic shape of an aerofoil. The camber of an airfoil is the curve of its upper & lower surfaces. Upper camber is more pronounced, whereas lower camber is flatter.
Stalling angleThe angle beyond which the aerofoil would experience loss of lift and controlled flight would not be sustainable.
Axis of aircraftLateral (pitching), Longitudinal (rolling), vertical (Yawing) Longitudinal – Aligned to Fore and Aft of aircraft Lateral – From wing tip to wing tip Vertical – Runs vertically as a Z axis
Primary Controls of an aircraftRudder – Yaw – Vertical Axis – Directional Stability

Aileron – Roll – Longitudinal axis – Lateral Stability

Elevator – Pitch Lateral Axis – Longitudinal Stability
What is an aircraft? What is an airplane? Difference....Aircraft – Any machine supported in the atmosphere by reaction of air (Baloon, kites, gliders)....

Airplane – Power-driven heavier than air aircraft which depends on fixed surfaces (mainly wings) for deriving its support in air.
What is an Aerodrome?Aerodrome - Definite or limited area of land or water which is wholly or part intended to be used for the landing and departure of aircraft
What is NDB?NDB – Non directional Beacon is a ground based radio transmitter that transmits radio energy in all directions.
What is VOR?VOR - Very high frequency omnidirectional range is electronic navigation equipment in which the flight deck equipment identifies the radial or line from VOR station measured in degree clockwise from magnetic north along which the aircraft is located.
What is ILS?ILS – Instrument landing system, An electronic system that provides both horizontal and vertical guidance to a specific runway used to execute a precision instrument approach procedure.
Meridian Definition?A semi great circle touching north and south poles and indicates north and south directions. The meridian passing through Greenwich town is referred to as zero meridian. A meridian is a semi great circle joining the Poles. They cut equator at 90. The opposite side of a meridian is it’s anti meridian.
How many meridians can be drawn between 2 points?There can be infinite meridians drawn between 2 points
What is definition of Prime Meridian?It is a semi great circle passing through Greenwich. It cuts the equator at 90 degrees
What is definition of Graticule?It is a grid or network of latitudes & longitudes.
Definition of Equator?It is a great circle perpendicular to the Earth’s minor axis & it divides the earth into Northern & Southern Hemispheres
What is the difference between Map & Chart?Map = Geographic Chart = information
Importance of Prime Meridian & it’s Anti MeridianThe Prime Meridian is designated as 'Longitude 000°' & it is the DATUM or reference for Longitudes. It is Greenwich Meridian
What is Zulu TimeIt is the UTC (Universal Time coordinated) or Greenwich mean time. Meridians to the East are ahead of UTC, and those to the West are behind