How Planes & Paper Airplanes Fly: An Explanation

[The_Thinker]

My question is very basic and fundamental... How do planes fly? I have read that the equal transit time explanation is not true... And I have read the NASA explanation, that's supposed to be true... But I really don't understand how it works even after reading... Anyone willing to help me out?

You can check out the NASA article here:

http://www.grc.nasa.gov/WWW/K-12/airplane/lifteq.html"

Okay... another thing... How do paper airplanes fly? or glide? I've scoured the net but have remained unsuccesfull in finding out how they work...

Would be very greatfull if someone helped me out...

 

[Langbein]

All airplanes including those made of paper makes their flight due to the difference in pressure between the upper and under surphase of the wing.

How this differencial pressure is set up can be a bit different.

On an ordinary aircraft wing (like that explained on the NASA page) the basic principle making this pressure difference is to increase the speed of the air passing over the upper wing suphase. When speed goes up, the static pressure goes down, and the lift is produced due to the differential pressure.

 

[Langbein]

http://travel.howstuffworks.com/airplane.htm

http://travel.howstuffworks.com/airplane8.htm

 

[The_Thinker]

hey... thanks for the links and replies... but as shown in the explanation, the wing must be tilted upward, must it not? but most paper airplane's wings are tilted downwards right?

Check the two attached pictures...

 

[Langbein]

When it comes to airplane wings it is generally a question of relative wind. Relative wind can be described as the wind direction that you would see if you were sitting at the tip of the wing. (It will come with some angle from underneath.)

The principe of "relative wind" is valid for aircraft wings, helicopeter rotors, aircraft propellers and also the first stage fan blades in big jet engines.

From paper planes and up to the biggest jet engines it work basically the same way.

There is one limit, when the speed of sound is reached for an airfoil, things are starting to work different.

 

[Langbein]

The relative wind has to make a positive "angle of attach" for any subsonic airfoil including a paper plane. (It is not how the airplane is flying that is important, but how it moves relative to the wind.)

http://www.dynamicflight.com/aerodynamics/relative_wind/

http://www.dynamicflight.com/aerodynamics/

http://www.dynamicflight.com/aerodynamics/aero_force/

 

[Langbein]

For the paper plane wing on your drawing, the direction of the plane has to be even more step to the ground so that "angle of attack" measured against relative wind is still positive.

 

[The_Thinker]

hey... thanks for replying, I've sort of got it now...