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Challenge Team Interim Report

Team Number: 066 School Name: Moriarty High School Area of Science: Fluid-dynamics Project Title: Aerodynamics

Project Definition

The purpose of our project is to show the correlation between lift and angle of attack.

Background

How does angle of attack effect the lift of the airfoil? There are many variables that influence lift. These include velocity, the density of the air, and the lift coefficient (lift produced by the overall design of the wing and by the angle of attack). Angle of attack refers to the angle at which the centerline of the wing is traveling through the air. Raising or lowering the angle of attack forces the air to travel at different speeds across the airfoil.

If you increase the angle of attack, the air on the top of the airfoil is forced to travel at a much higher rate than that of the bottom of the airfoil. This causes a difference in pressure to occur, thus creating lift. The same feat can be accomplished be changing the wing's design. The angle at which the wing naturally sits (Camber angle) is a constant for a given aircraft. This causes the wing to travel through the air at an angle that is naturally more (or less) than zero. For a wing like this, the angle of attack is defined as the angle the wing would be traveling at if its initial angle was zero. In other words, the angel of attack is figured by assuming the wing was at an angle of zero to begin with (no camber). This is taken into account in our math model as the coefficient lift at zero angle of attack.

Proposed Method of Solution

In order to model the lift of an airfoil, we will implement a C++ program. This program asks the user to choose a plane from a list and proceeds to gather all the necessary information for the math model. The math model is:

• Lift = CL * 0.5 * p * V^2 * S

  Where:

• Lift = the lift produced by the wing
• p (Greek letter rho) = the air density
• V = the velocity of the airfoil
• S = wing area
• CL = the lift coefficient

  Also:

• CL = a * alpha * CL0

  Where:

• alpha = the angle of attack in radians
• CL0 = the coefficient lift at 0 angle (constant for the plane)
• a = the gradient lift curve (a function of wing geometry)

For the ease of use we are using a constant of 2*pi for "a". This is because it is hard to find the aspect ratio for the wings. If we find them then we will add this to our program at a later date.

Expected Results

We hypothesize that the lift will continue to go up as the angle of attack is increased and go down as it is decreased. We are going to use a graphing utility to show the results of our program. We will then use the graphs to show the relationship of angle of attack and lift at various altitudes and on different types of airplanes.

Bibliography

http://www.desktopaero.com/appliedaero/appliedaero.html, October 99.
http://www.af.mil/news/indexpages/fs_index.html, October 99.
Auld, Doug. Aeronautical engineering department, University of Sydney, Australia. Available e-mail: douga@aero.usyd.edu.au October 12, 1999

Team Members

Team Mail

• Travis Cochran
• Josh Bennett
• Nick Roy

Sponsoring Teachers

• Puala Avery

Project Advisor(s)

• Doug Auld