Projectile motion with drag and lift

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SUMMARY

The discussion focuses on solving projectile motion problems involving drag and lift forces for an object tested in a wind tunnel. The initial velocity is 76 m/s, with launch angles of 30, 45, and 60 degrees, and gravity set at 9.81 m/s². The user has tabulated lift and drag forces at wind speeds of 80, 130, and 170 mph, varying the angle of attack from -10 to 30 degrees. The user identified a linear relationship between wind speed and drag values but encountered discrepancies when applying these to the ideal projectile motion equations, indicating a need for further analysis of the lift and drag coefficients (Cl and Cd).

PREREQUISITES
  • Understanding of projectile motion equations
  • Familiarity with lift and drag force calculations
  • Knowledge of aerodynamic coefficients (Cl and Cd)
  • Experience with data interpolation and integration techniques
NEXT STEPS
  • Calculate Cl and Cd using the provided lift and drag data
  • Learn about integrating acceleration terms in projectile motion
  • Research the effects of varying angles of attack on drag and lift
  • Explore numerical methods for solving differential equations in motion analysis
USEFUL FOR

Aerospace engineers, physics students, and anyone involved in fluid dynamics or projectile motion analysis will benefit from this discussion.

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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 don't make sense. Is there another way I can do this or am I missing some important information to solve this problem
 
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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 won't match. Can you guess why?
 
Last edited:

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