Posts

Showing posts from April, 2021

Wing Twist

Image
  Wing twist is of two types named as geometric twist and aerodynamic twist:- Geometric Twist Different angles of attack at wing root and tip. Wash in Tip chord has a higher angle of attack than that of root chord. Wash out Angle of attack at tip is lower than that at wing root. It is useful in reducing tip vortices. Aerodynamic Twist Difference between zero-lift lines of airfoils at wing root and near the tip. Airfoils at root and near the tip have different zero lift angles of attack.

How to draw Airfoils ?

Image
Airfoils are rather simple geometrical objects as they are nothing but a curve drawn on a flat plane of paper, defined by coordinates usually by two columns namely, x and y. They define airfoil as locus of points where each point is defined by a set of x and y coordinates. It can be created of 50 or 100 points depending on the chord length decided as per the requirements. To draw airfoils, you have various tools available like:-  1.   Software   They work on the airfoil coordinates available in dat file and use it to plot airfoil on the screen which can be printed afterwards. Some of the software available out there include Catia, Solidworks, AutoCAD, Xfoil and Concord (conversion of airfoil coordinates).  2.   Online plotter   It includes various websites having with them airfoil database which is available for all, you can just select airfoil needed from the list or else you can enter the details like LE radius, chord, camber to plot airfoil whi...

How to calculate Mean Aerodynamic Chord?

Image
Mean Aerodynamic Chord  The distance between leading and trailing edge of the wing, measured parallel to the normal airflow over the wing, is known as the chord. If the leading edge and trailing edge of the wing are parallel then, chord is constant along the span. Most commercial or fighter aircrafts have swept or delta wings in which chord length is greater at the root than at the tip. Consequently, chord changes along the span of the wing. The average length of Chord is known as Mean Aerodynamic Chord.  It has a geometrical importance as CG should be located at certain point of the MAC in percentage of its length. So, the location of MAC is specific and it can be found out as: Locating MAC Measure the root and tip chord and draw following points on plane : At the root of the wing, draw a line parallel to the fuselage centerline extending forward from leading edge and rearward from the trailing edge. Both lines should be the length of tip chord. Do the same thing at the tip b...

Types of Airspeed

Image
Measuring speed on ground is much easier for vehicles like cars, buses, bikes, etc. by the use of speedometer but in the case of aircraft. Airspeed is not simply what you see inside the cockpit reading through the indicator. Depending upon the instrumentation terms and physical properties of air, Airspeed can be classified as : 1. Indicated Airspeed  Airspeed as indicated by the airspeed indicator inside cockpit that the pilot reference for speed changes. Indicated airspeed is the measured speed of an aircraft as it moves through the air, it is based on the pressure readings collected by the pitot-static system. It changes with the altitude as at higher altitudes the density of air is low and there are fewer molecules to enter the pitot tube and create pressure hence, Indicated airspeed decreases during climb. 2. Calibrated Airspeed Calibrated airspeed is the indicated airspeed corrected for instrument and positional errors. At certain airspeed and flap settings instrumental errors...

Popular posts from this blog

NACA Airfoil Nomenclature

Wing Twist

How to calculate Mean Aerodynamic Chord?