334 AAE Fall 2011
Quiz 1.
SOLUTIONS
Circle True or False or neither of the two. Points: +1 for correct, -1 for incorrect, 0 for blank. Ambiguous answers are scored as incorrect answers. All questions concern the classical thin airfoil theory which we have studied to date in the class.
1
True
False
The Kutta-Joukowsky theorem shows that lift is proportional to the product of vorticity (which we also call "circulation") and dynamic pressure. velocity, not dynamic pressure The chord line and the camber line differ except for symmetric airfoils. The zero-lift angle of attack depends on airfoil shape and flight velocity. Is independent of flight velocity. The definitions of the A0 , A1 , and A2 coefficient include an integral of the slope of the thickness distribution of the airfoil. Slope of camber line, not of the thickness distribution. The lift coefficient for a symmetric airfoil at 1 degree of angle attack is approximately 6.28. The cl = 2 formula is for radians, not degrees. The Kutta condition sets the induced velocity to be the negative of the normal component of the flight velocity everywhere on the camber line That's a boundary condition, not the Kutta condition. The Superlinear Principle of Position states that when we add together two velocity potentials, the sum is also a velocity potential. "Principle of Linear Superposition" says this. The angle of attack is the angle between the chord line and the velocity vector of the free stream. Bernoulli's equation or law defines dynamic pressure, q, as 1 q = V 2 2 Uses dynamic pressure, doesn't define it.
2
True
False
3
True
False
4
True
False
5
True
False
6
True
False
7
True
False
8
True
False
9
True
False
10
True
False
Thin airfoil theory is useful for airfoils with some but not too much thickness.