Aerodinamics 2

Question 0

Relative Wind

fix wing

Answer 0

Direction of the airflow with respect to the wing and is created by the motion of the AC moving through the air

Question 1

Angle of Incidence

Answer 1

formed by the longitudinal axis of the aircraft and the chord of the wing

Question 2

Angle of Attack

Answer 2

Angle between the wing chord line and the direction of the relative wind

Question 3

Swirling or Burbling

Answer 3

when air can no longer flow smoothly over the wings upper surface due to the separation of the boundary layer

Question 4

Thrust and drag in straight and level flight

Answer 4

Drag increases twice as much as increases airspeed

Question 5

Lift and gravity in straight and level flight

Answer 5

if lift becomes less than weight, the AC will descent, and if lift becomes greater than weight, the AC will climb

Question 6

Wing Area

Answer 6

The lift and drag acting on a wing are roughly proportional to the wing area

Question 7

Airfoil Shape

Answer 7

As the upper curvature or camber of an airfoil increased, the lift produced increases.

Question 8

Basis for all helicopter flight

Answer 8

Vertical, forward, backwards, sideward, or hovering

Question 9

All opposing forces are in balanced

Answer 9

At a hover

Question 10

Relative Wind

Rotary wind

Answer 10

moves in a parallel, but opposite, direction to the movement of the airfoil

Question 11

Rotational Velocity

blade speed

Answer 11

near the main rotor shaft is much less, because the distance traveled at the smaller radius is relatively small

Question 12

Hovering

Answer 12

Helicopter maintains a constant position over a selected point

Question 13

Rotor Tip Vortex

Answer 13

The rotor tip vortex reduces the effectiveness of the outer blade portions.

Question 14

OGE

Answer 14

out-of-ground-effect

High-power requirement needed to hover

Question 15

IGE

Answer 15

in-ground-effect

Improved performance encountered when operating near the ground

Question 16

Induced Flow

Answer 16

Produced during OGE, the rotor blades move large volumes of air in a downward direction

Question 17

Induced Flow speed

Answer 17

May reach 60 to 100 knots, depending on the size and gross weight

Question 18

Translating Tendency

Answer 18

A single rotor helicopter has a tendency to drift laterally to the right

Question 19

Translational Lift

Answer 19

Improved rotor efficiency resulting from directional flight

Question 20

Dissymmetry of lift

Answer 20

the difference in lift between the advancing half of the rotor disk and the retreating half. Max at 3 o’clock, min at 9 o’clock.

Question 21

Gyroscopic Precession

Answer 21

A phenomenon occurring in rotating bodies in which an applied force is manifested 90* ahead of the direction of rotation from where the force was applied

Question 22

Autorotation

Answer 22

Some other force must be used to sustain rotor RPM so controlled flight can be continued to the ground

Question 23

Autorotation Phases

Answer 23

Entry
Steady-State Descent
Deceleration and Touchdown

Question 24

Entry

Answer 24

Performed following a loss of engine power. Rotor RPM should be stabilized at autorotation RPM (higher than normal RPM)

Question 25

Steady-State Descent

Answer 25

Rate of descent and RPM are stabilized, the helicopter descents at a constant angle. AOA descent normally 17-20 degrees.

Question 26

Deceleration and Touchdown

Answer 26

Must reduce airspeed and rate of descent just before touchdown

Question 27

Torque

Answer 27

the helicopter tends to rotate in the direction opposite the rotor blades

Question 28

Anti-torque rotor

Answer 28

Compensation for torque in the single main rotor helicopter is done by means of a variable pitch, anti torque rotor. 5-15% engine power may be needed to drive the tail rotor.

Question 29

Blade flapping

Answer 29

Up and down movement of the rotor blade which causes elimination of dissymmetry of lift.

Question 30

Retreating Blade Stall

Answer 30

as the speed of the retreating blade decreases with forward speed, the blade AOA must be increased to equalize lift throughout the rotor disk area

Question 31

Produce blade stall at high forward speeds

Answer 31

``` High blade loading Low rotor RPM High density altitude Steep or abrupt turns Turbulent air ```

Question 32

Warnings of approaching retreating blade stall

Answer 32

Abnormal vibration Pitch up of the nose Tendency for the helicopter to roll in the direction of the stalled side

Question 33

Prevent blade stall

Answer 33

``` Fly slower then normal: DA is much higher then standard Carrying Max gross loads Flying high drag configurations The air is turbulent ```

Question 34

Blade stall may be eliminated by..

Answer 34

Decrease collective pitch Decrease the severity of the maneuver Gradually decrease airspeed Increase rotor RPM

Question 35

Blade lead and lag

Answer 35

Fully articulated rotors have hinged blades that are free to move fore and aft in the plane of rotation independent of the other blades in the system.

Question 36

Coriolis Force

Answer 36

Causes blades to lead and lag

Question 37

Conservation of Angular Momentum

Answer 37

A rotating body will continue to rotate with the same rotational velocity until some external force is applied to change the speed of rotation

Question 38

Settling with power

Answer 38

Can occur at any airspeed or altitude whenever power required exceeds power available, preventing level flight.

Question 39

Vortex Ring State

Answer 39

May develop at any ALT or gross weight when the airspeed is bellow translational lift and rate if descent is high (excess of 300ft/min)