# Projectile motion with drag and lift

1. Nov 4, 2009

### Simms16

I obtained lift and drag forces for an object I was testing in a wind tunnel and I wanted to know if it was possible to do a projectile motion problem with the following variables;
I know the initial velocity of the object, V=76m/s, the possible launch angles = 30, 45, or 60 degrees, and gravity = 9.81m/s^2.

-I also have tabulated data of the lift and drag forces on the object at 3 different wind speeds (80, 130, 170 mph) while varying the angle of attack (AOA) from -10 to 30 degrees.
I took the three drag values at 0 degrees AOA and found a linear relationship between the wind speed and drag values. I used that relationship and subtracted drag off of the ideal equations of distance and height of projectile motion and the values I got dont make sense. Is there another way I can do this or am I missing some important information to solve this problem

2. Nov 4, 2009

### ank_gl

Ideal case#
Ax = 0
Ay = -g

Practical Case#
Ax = -Drag/mass
Drag = -Cd.(Area.rho.V^2)/2

Ay = -g + lift/mass
Lift = -Cl.(Area.rho.V^2)/2

You have the data, calculate Cl & Cd at the data points, interpolate to get Cl & Cd in terms of V, integrate twice the acceleration term to get the distance.

Note: The actual & calculated value still wont match. Can you guess why?

Last edited: Nov 4, 2009