Rotary

Question 1

Criteria for Good Airfoil / Rotor Blade? (7)

Answer 1

High max static and dynamic lift coefficient
High drag divergence Mach number
Low drag
Low pitching moment
Aft aerodynamic centre position
Sufficient thickness
Easy to manufacture

Question 2

Coning Angle

Answer 2

Is the angle between Tip Path Plane and Blade

Question 3

Blade Pitch Angle

Answer 3

Is the angle between the chord of the airfoil selection and the Plane of Rotation. An increase to Pitch Angle results in an increase to lift.

Question 4

Angle of Attack

Answer 4

Is the angle between the airfoil chord with the direction of the relative wind?

Question 5

Momentum Theory calculates Thrust (T) directly, where?

Answer 5

T = [mass flow per sec] x [total change in velocity]

Question 6

Using Newton’s 2nd Law and Bernoulli’s Theorem, V2 = 2V1, where V1 is the induced velocity which is axial to the Rotor Disc, and V2 is the induced velocity in the remote wake, also known as?

Answer 6

Rotor Downwash

Question 7

Lift Forces on Blades depends on? (3)

Answer 7

Pitch Angle of Blade
Speed of Blade Rotation
Density of Air

Question 8

Rotor Hinges (3)

Answer 8

Flapping Hinge [Vertical]
Feathering Hinge [Horizontal]
Drag Hinge

Question 9

What is introduced on the main rotor to avoid load variation from root to tip?

Answer 9

Blade twist

Question 10

• Collective Pitch Lever for ______.
• Cyclic Pitch Stick for ______, _____ and _____
• Pedals for ___.

Answer 10

• Collective Pitch Lever for Vertical Movement.
• Cyclic Pitch Stick for Horizontal Movement, Tilt and Roll
• Pedals for Yaw.

Question 11

The limitation to the forward speed of a rotary wing is due to?

Answer 11

The blade tip passing into the transonic speed regime, which results in a loss in lift and increases to drag, thus preventing further increases to speed.