Introduction

The study of aerodynamics can be complicated for people who do not initially understand the basics. I have created this blog to be used by students who want to create a solid foundation for the study of Aerodynamics. I have attempted to create a blog that teaches by example the key main points. I feel that examples make a lasting impression where as simply reading the material is less effective. This blog also encompasses information on what can be achieved once a solid understanding of aerodynamics is achieved.

Hope you enjoy and find this blog helpful.

Forces Acting on an Airplane in Flight

There are 4 main forces that affect an airplane in flight, these forces are:

1. Thrust: “Provides the forward motion of an airplane created by the backward force created by the engines and its propeller(s).” (MacDonald, 2000)

2. Drag: The resistance to forward motion directly opposed to thrust. There are two principal types of drag parasite and included. Parasite drag is any type of resistance from parts of the aircraft that do not contribute to lift such as the fuselage, landing gear or antennas. Induced drag is caused by parts of the aircraft that are active in producing lift mainly being the wings.

3. Lift: The force upward which sustains the airplane in flight. Lift is created when an airfoil (or wing) is introduced into a streamlined airflow. The air must travel a further distance over the top of the wing than over the lower edge of the wing, to compensate for this further distance the air must then increase thus reducing its pressure (See: Why is Bernoulli’s Principle is Important to Aerodynamics?). The air flowing underneath the wing also does not just flow rearward but also flows downward as well also creating additional lift.

4. Weight: The downward force due to gravity which directly opposes lift. Weight is simply attributed by the weight of the aircraft, and all of its contents and components.

For further information on the 4 forces and how they affect flight please visit this slideshow at http://www.planemath.com/activities/pmenterprises/forces/forces2.html
This link contains a page with many useful sites relating to Aerodynamics: http://www.dmoz.org/Science/Technology/Aerospace/Aeronautics/Aerodynamics/

Why is Bernoulli’s Principle Important to Aerodynamics?

Bernoulli’s Principle acts as the building blocks for all aerodynamics. Bernoulli’s Principle is the law, discovered by Daniel Bernoulli an eighteenth-century Swiss scientist, that the as velocity of a fluid (including air) increases, its pressure decreases. How an airplane flies can be explained by this principal. Keep in mind: “When a fluid increases its speed it reduces its pressure.” (MacDonald, 2000)
As seen in the diagram due to the shape of the wing the air over the wing has a further distance to travel to get to the back of the wing thus it must increase its speed to get to the back of the wing and by doing so reduces the downward pressure on the top of the wing, creating lift.

Simple Aerodynamic Experiments

Lift Test

An easy way to demonstrate lift and Bernoulli's principle is to get a regular piece of paper and cut it in half lengthwise, put one end in a test book and allow the other end to hang over the top. The paper will represent a wing. Now, blow across the top of the paper. What happens? The paper will rise. This is because the air over top of the "wing" is moving faster which decreases the pressure.

Drag Test

Get two identical pieces of paper. Crumple one and put it in your hand, in the other place the other sheet flat on your hand. Drop the two pieces of paper at the same time. The crumpled ball will reach the ground first. This occurs because the flat piece of paper has a larger surface area and creates more drag than the other so it moving it more slowly through the air.

Reduction in Pressure Test (Bernoulli's Principle)

Get two empty pop cans place them near the edge of a table side by side with a 3 or 4 inch gap in between them. Now, blow between the two cans from table level. The cans will come together due to the reduction of pressure created by the rapidly moving air in between them.
Further examples for this principle in
http://www.youtube.com/watch?v=5YHqCkCJbWQ&feature=related

Jobs Involving Aerodynamics

At first one might think that the skills you learn in aerodynamics can only be applied to airplanes, but this is not the case. The study of aerodynamics is far beyond limited to just aerospace engineering. Knowledge of aerodynamics is useful in a wide range of technological fields; the reason being is the very common occurrence of flow phenomena we see in everyday life.

Aerodynamics is very important when it comes to any type of vehicle design – cars, boats, and planes. Aerodynamics is also very important for sailors, in order that they can properly predict proper sail adjustment in order to maximize speed. Structural engineers use aerodynamics when designing and building large bridges and buildings. Aerodynamics can also be significant in the design of a town so as to create a more comfortable outdoor environment or an urban microclimate; additionally, it may also be used to reduce the effects of pollution. Environmentally, aerodynamics can be used in the prediction of weather and the study of atmospheric circulation. It can also be used in understanding how various birds and insects fly. Aerodynamics is also very important when it comes to the study of internal passageways such as piping – gas piping, heating and ventilation, and automotive engines. The study of aerodynamics can even be extended to studying the human respiratory system. The aerodynamicist often works in an environment “where he, together with colleagues from various disciplines, incorporates the abundance of (often) conflicting demands in the
fields of aerodynamics, performance, structures, safety, materials and manufacturing into a technical, economical, and ecological sound compromise”. (TuDelft 2006)

While skills in aerodynamics can be useful in many fields, the most rewarding and fascinating career for an aerodynamicist, the one the most seek to pursue is aircraft and spacecraft design. It is in this field where you can be involved in designing the more efficient and future friendly air and spacecraft of tomorrow.

The list of jobs available to an aerodynamicist is extremely extensive, and for this reason there will always be generous employment available for an engineer who has expertise in aerodynamics.

Web Sources and References

Web Sources

"Graduate Study in Aerodynamics and Computational Fluid Dynamics." TUDelft. May 2006. 1 Aug. 2008 .

This site was operated by TU Delft Aerospace Engineering, a university dedicated to the study of aerospace engineering. Contained within the site was an information brochure dedicated to the study of aerodynamics and the many possibilities of careers related to this study. The site outlines that there is more than just Aerospace options out there for people with knowledge in this field.

Benson, Tom. "Simplified Aircraft Motion." 11 July 2008. NASA. 15 July 2008 http://www.grc.nasa.gov/WWW/K-12/airplane/smotion.html

The National Aeronautics and Space Administration is an American organization that is dedicated to the advancement of space exploration, scientific discovery and aeronautic research. This site consists of, among many other things, many useful sources of information for anyone at any level of Aerodynamic knowledge.


References

MacDonald, A F., and Isabel L. Peppler. From the Ground Up. Ottazwa: Aviation Co. Limited, 2000.

Smith, H C. The Illustrated Guide to Aerodynamics. New York: TAB Books, 1992.