Basics of Aerodynamics

Tuesday, August 3, 2010

BASICS OF AERODYNAMICS

Well , i read many articles and tried to search in lots of books for easy understanding of various terms in aerodynamics and their origins... but have found only few.

Thus here i am trying to simplify the concepts and basics of aerodynamics for people who likes to start from the scratch in field of aerodynamics and aeronautics.

Aerodynamics :

Aerodynamics is a branch of dynamics (in Physics) that actually concerns with the study of motion of air , specially when a object moves in air.

Derived from Fluid Dynamics and Gas dynamics...it has made way not only to the frequently used mode of transportation i.e aircraft but also has made possible to fly at speed higher than sound (greater than sonic speeds) with huge advancements in defense aircrafts and even in high speed trains and formula one (F1) racing car designs.


Origins of Aerodynamics :

It was very difficult to understand how aerodynamics came to existence. then i came across a book which actually discussed few historical examples ... given here are those examples as there is no better way i found than these to explain the origins.

" On 8th August, 1588 , the waters of English Channel churned with gyrations of hundreds of warships. The great Spanish Armada had arrived to carry out an invasion of Elizabethan England and was met head-on by the English fleet under the command of Sir Francis Drake. The Spanish warships were large, heavy, packed with soldiers and carried formidable weapons. In contrast, English ships were smaller, lighter, had no soldiers on-board and armed with lighter and short-range cannons.
The balance of power in europe hinged on the outcome of this naval combat. On that crucial day of 1588, when the English floated six fire-ships into the Spanish formation and drove headlong into the ensuing confusion, the history of Europe was in balance.

The heavier, sluggish, Spanish ships were no match for the faster , more maneuverable, English ships and by that evening Spanish armada lay in disarray, no longer a threat to England. This naval battle is of particular importance as it was first battle to be fought by ships on both sides powered completely by sail (wind).

It taught the importance of Naval power to politicians, in turn naval power became dependent greatly on speed and maneuverability of the ships. To increase the speed of ships, it is important to reduce the resistance created by the water flow around the ship's hull. Suddenly, the resistance or drag on the ship's hull became an interesting engineering problem, thus, encouraging people to the study of FLUID MECHANICS / DYNAMICS. "

Images showing Bow and Hull of the ships.

Aircraft Wing Design Developments :

I will here omit information on developments and equations given by Sir Isaac Newton,which made him first aerodynamicists, or by Jean Le Rond d'Alembert or by Leonhard Euler and Bernoulli , as these relates with the flow of fluid around the body which comes in advance aerodynamics and fluid flow which definitely is not for the beginners and purpose of my writing this article is to simplify the study...

In summer of 1901, Oliver and Wilber Wright , were struggling to make a successful glider design, at Kill Devil Hills , 4 miles south of Kitty Hawk ( North Carolina)

The aerofoil & wing design of glider were based on aerodynamic data published in 1890, by great German aviation pioneer Otto Lilienthal and by Samuel Pierpont Langley.

Due to constant failures, Wilbur wrote "Having set out with absolute faith in the existing scientific data, we are driven to doubt on thing after another, untill finally after 2 years of experiment , we cast it all aside & decide to rely entirely upon our own investigations."

In fall of 1901, they designed & built a 6 ft. long, 16 inch sq. wind tunnel powered by a two bladed fan connected to a gasoline engine. ( which became the first wind tunnel ). They tested various airofoils / wing designs. the data collected are taken logically and carefully. In spring 1902, they design a new glider with the improved and new information collected. Rest is all astounding history.


Thus , this was how humans learned to fly, with the deliberate and constant hard-work and study of the enthusiasts in aircraft designs.


Parts of Aircraft: Its becomes important to newbies , to understand various parts of aircraft and their uses , before jumping on various concepts and theories that actually formed the aircrafts.

Displayed below, are the most important parts or basic parts , which are required to create a stable flight of an airplane in today's time..

CAD image of a civilian aircraft.

CAD image of a military aircraft.

Parts / Terms Description:

1. Fin - Used to improve the balance or stability of the aircraft.

2. Rudder - Direction control of aircraft , in horizontal plane.

3. Tailplane - Small wing at back of the aircraft. It is fixed & thus mostly absent in military aircraft.

4. Elevon / Elevator - Part of tail-plane in aircraft, for vertical (altitude) climb and descent.

5. Fuselage - The main part of the aircraft. A cigar shape body to which wings, tailplane & fin are attached.

6. Aileron - A part of the wings, which are used for turning the aircraft in left or right direction i.e. control its roll movement. These are also moved up and down to control aircraft balance.

7. Flaps - Part of wings, which are moved up & down to control the altitude movement in sustained and gradual way unlike elevators which does in improper variations.

8. Leading Edges / Slats - The front or forward edge of the aircraft wings. These are generally slotted for generating proper air flow around the wing during take-off and landing.

9. Nose Cone - Front part of the fuselage, where RADAR and other navigation , control and avionics equipments are stored.

10. Cockpit / Flight Deck - Area at the front os a large plane where pilot, copilot sits to control the aircraft.

11. Canopy - The glass window or covering in fighter aircrafts. These are unbreakable, flexible , movable and sometimes have explosives embedded in them for emergency ejection time.

12. Engines - Main and heart of the aircraft. Classified usually as - Turbo Prop, Turbo Jet, Propeller and Pulse Jet. Gives power to aircraft's avionics as well as generates lift to fly the aircraft.

13. Engine Cowling - Metal covering for an engine.

14. Starboard Wing - Right side wing of the aircraft.

15. Port Wing - Left side wing of the aircraft.

16. Spoilers - It is a part of the wing and sometimes fuselage. As its name is, so is its work, it spoils the sustained flight by increasing the drag of the aircraft and reducing the altitude of the aircraft. It is also used as air-brakes and used in combination with flaps during landings.

17. Lift - Upward force generated by the flow of air around the airfoil/wing.

18. Drag - Resistive force experienced by the aircraft body by air due to its forward motion.

19. Thrust - Its the force experienced by the aircraft which helps it to move forward and fly.

The value of thrust and lift components should be higher than weight and drag components for an aircraft to fly.

All the aircraft designs are basically modifying these four components as per the desired requirements and situations. These components are varied, to make a flight either more stable, or Maneuverable or during take-off or landing of an aircraft.

20. Shockwaves / Bow-Shock - It is not a part of aircraft, plays an vital and crucial role in flight of an aircraft. To understand them lets move back to the concept of Fluid Dynamics as discussed above.

As boats moves in water , making a way by removing water from its way , a trail is created. Similarly, when a object moves in air it makes its way by removing air particles from its way.

The speed of the particles being very less in comparison to the speed of the object, thus the air particles are not able to move away from the aircraft's body faster, thus , a wave (trail as with boats) is created known as shock-waves or bow-shock. These are not visible , unlike trail in water, but can be seen using UV spectrum or when a aircraft breaks sonic barrier at a low altitude it can be seen due to condensation around the aircraft's body.