1. Aerodynamics
Dane Johannessen

2. Overview Aerodynamics What are the forces?
How do these forces affect flight?
What factors affect these forces?

3. What is Aerodynamics?
The study of forces acting on an object in motion as it passes through air.

4. Laws of Motion Objects in motion stay in motion
Force is the change in momentum with respect to time
For constant mass
For every action there is an equal and opposite reaction

5. What are the forces?
Lift
Drag
Weight
Thrust

6. Lift The vertical forces pushing up on a body during flight.
General Equation:
L = Lift Force
ρ = density
v = velociy
A = area
Cl = Lift coefficient that is usually determined experimentally

7. Lift in Air Foils
Based on pressure differences (Bernoulli’s Principle)
Top
Higher velocity and decreased pressure
Bottom
Lower velocity increased pressure

8. Factors Affecting Lift
Shape of object
Higher curve = greater lift
Size of the object
L = constant x A
Velocity of the object
L = constant x v²
Properties of the air
L = constant x ρ
Angle of attack
Increased angle = increased lift

9. Demonstration For more information on paper airplanes
Go here

10. Drag Drag is the force that acts in the same direction as airflow
General Equation:
Fd = Drag Force
ρ = density
v = velocity
A = area
Cd = Drag Coefficient that is usually determined experimentally

11. How Shape Affects Drag
Different shapes of the same frontal area lead to different drag coefficients:

12. Lift to Drag Ratio
General Equation:

13. Weight Weight is the force on an object due to gravity
Based on mass and gravitational acceleration
General Equation:
W = Weight Force
m = mass
g = gravity

14. Thrust Thrust is the force that propels an object through air
General Equation:
F = thrust force
t = time
m = mass
v = velocity
ṁ = mass flow rate
ṁ = ρvA

15. Thrust Producers of thrust Main thing to take away Propellers
Fans in jet engines
Hot gases from rocket engines
Main thing to take away
Thrust must be greater than weight

16. Thrust to Weight Ratio General Equation: If F/W is high
High acceleration
High Climb rate
If F/W > 1.0
Acceleration can be vertical

17. Summary Aerodynamics 4 Forces on a plane Lift > Drag
Dependent on shape, size, velocity, air, angle
Drag
Dependent on shape
Weight
Thrust
Lift > Drag
Thrust > Weight

18. Sources Helpful Websites

19. Questions?