Basic Flight Aerodynamics ( PART - 11 )

Kinetic Heating: Heating effect occur for supersonic aircraft. Surface area of supersonic range 2000 degree c; Aluminium tolerant range 100 degree c; Titanium & stainless steel: Glass is used for thin of streamline for smoothly. Kinetic heating also called heat effect.

Normal stall:  Normal stall is the reduction in the lift co-efficient generated by an airfoil as angle of attack increases. This occurs when the critical angle of attack of the airfoil is exceeded. 

Area ruling: This is also known as transonic  area ruling, which is a design technique reducing  an aircraft's drag at transonic & supersonic speeds, particularly between mach 0.75 &1.2

Basic Flight Aerodynamics ( PART -10 )

Few Important Definition On Aerodynamics : 

Angle Of Attack  with relative airflow

• Angle Of Attack (AOA) : Generally , AOA is the angle between airfoil chord line (line of a body) & relative airflow which acts oppositely. The AOA is so important in fluid dynamics, becuse Aircraft take off, land & gain altitude always depends on that angle.
• Angle Of Incidence (AOI) : Longitudinal axis is making angle with aircraft (airfoil) wing is called Angle Of Incidence (AOI). It is also known as Manufacture angle.
• Laminar Airflow : In which the streamlines are smooth & fluid elements move regularly along a streamline. 
• Turbulent Airflow : In which the streamlines are break up & fluid elements move in a random & irregularly.   
• Shock Stall : Shock stall is the separation of boundary layer & making disturbance. It is occurred, when the airflow is near by critical mach number (0.8-0.9).
• Sonic Bang : When the aircraft (airfoil) move fast & faster at subsonic range, then toward to the sonic & supersonic range. when the airflow is passed sonic range or sonic range area is called sonic Bang.              

Basic Flight Aerodynamics (PART -9)

Four main flight forces: 

Weight: Weight is the force of gravity. It acts in a downward direction—toward the center of the Earth.

 Lift: Lift is the force that acts at a right angle to the direction of motion through the air. Lift is created by differences in air pressure.

Thrust: Thrust is the force that propels a flying machine in the direction of motion. Engines produce thrust.

 Drag:  is the force that acts opposite to the direction of motion. Drag is caused by friction and differences in air pressure.

Four main flight forces of an airfoil

                          

 

Basic Flight Aerodynamics ( PART -8 )

Critical Mach Number :  When the airflow  is in subsonic range, mach number will be near by  1.0 , approximate 0.8 - 0.9 ( where airflow speed is so high ).

Speed Of Sound : Speed of sound always follows on temperature .The speed of sound drops by approximately 45 m/s. Considering Temperature & height, speed of sound are different.



      Height (km)    Temperature (dk)      Speed of sound(m/s)

    Sea level                    288                           340.3
    
      3.0                            269                           328.6

      6.0                            249                           316.5

      9.0                            230                           304.0

    12.0                            217                           295.0

Basic Flight Aerodynamics ( PART -7 )

Table of Mach Number : 


                    Regime                     Mach                      Speed (m/s)

            Subsonic                  <0.8/1.0                      < 270
        
            Transonic                  0.8 -1.2                      270 - 410

             Sonic                         1.0                             ------------

             Supersonic               1.2 - 5.0                     410 - 1710

             Hypersonic              5.0 - 10.0                  1710 - 3415

             High-Hypersonic   10.0 - 25.0                 3415 - 8465

             
 
       

Basic Flight Aerodynamics ( PART -6 )

Mach Number: Mach number is  a dimensionless quantity representing the ratio between speed of an object & speed of sound. By definition,

                                           M =  V:Vs  
                                                                               [ Where,

                                                                                  M = Mach number;
                                                                                  V  = Speed of object;
                                                                                Vs  = Speed of sound. ]

Basic Flight Aerodynamics (PART -5)

Types of  Airflow: By considering air speed, airflow are two types. They are : 

• Compressible Airflow : When the airflow is passing airfoil surface & compressing every movement that means changing the density of the fluid elements from point to point. It is called compressible airflow. It is occurred on airfoil for the supersonic range speeds (Mach Number : 1.2 -5.0). 

• In-compressible Airflow : Such kind of airflow is always in-compressible that means the flow is never changed or constant , when passing the airfoil surface is called in-compressible airflow. It is occurred on airfoil for the subsonic range speeds (Mach Number : less than 0.8 / 1.0).