Midterm Flashcards
Name the different types of tail rotor systems.
Traditional anti torque system/ r-44/22
Fenestron
Notar
List five things that make up a airfoil.
Upper camber Lower camber Lead edge Trailing edge Chord line
What is the difference between an asymmetrical airfoil and symmetrical airfoil?
Symmetrical means that the upper and lower cambers are the same when asymmetrical each side is different. On a symmetrical airfoil no lift is being created at zero AOA while with asymmetrical airfoils they create lift as soon as forward airspeed is introduced.
What are the four forces of flight?
Lift, drag, weight, thrust
What is Bernoulli’s principle?
Is as velocity increases pressure and temperature decrease.
What are the different types of drag? (Explain each one)
Induced drag- that part of the airfoil that arises from development of lift. Worse at low airspeed or at hover and goes down with increase airspeed.
Parasite drag - drag that is created by non lifting components.(skids, rivets, mast, pitot, etc.) low drag at low air speeds and drag increases moderately with increased airspeed.
Profile drag - consist of form drag and skin friction. Drag incurred from frictional or parasitic resistance of the blades passing through the air. Form drag is part of the drag that arises based on shape and angle of attack of an airfoil. It can be decrease by streamlining. Increases moderately as airspeed increases.
Label the three axis of rotation.
Vertical - yaw
Longitudinal - roll
Lateral - pitch
Describe ground effect.
Occurs within one rotor diameter of the ground pushing vortices outward more horizontally which increases performance and lift while lowering induced drag
What is coming?
An upward sweep of the rotor blades as a result of centrifugal force and lift.
What is Coriolis effect?
As the center of mass of a spinning object gets closer to its axis of rotation, rotation rate increases.
What is dissymmetry of lift? How do we compensate for it?
The unequal lift across the rotor disk resulting from the difference in velocity of air over the advancing and retreating half of the rotor disk area. We compensate for it with flapping.
What is translational lift?
The additional lift obtained when entering forward flight, due to the increased efficiency over the rotor system.
What is the lift equation?
L= CL x 1/2q x S x V^2
Blade flapping.
As the advancing blade begins to flap up the AOA _________.
As the retreating blade begins to flap down the AOA __________.
Decreases
Increases
What are the six contributing factors to retreating blade stall? Name the three we can control last.
Density altitude High gross weight Turbulence Steep bank angles Low rotor Exceeding Vne
What is ground resonance?
Striking the ground or a fixed object at an angle that cause the rotor system to become in sync or out of balance resulting in self destructive vibrations.
Fix by stopping rotor blades as fast as you can or by pulling power and get off ground centrifugal force will correct it
What are the two properties of a gyro?
Gyroscopic precession
Rigidity in space
What is translating tendency?
The tendency of a single rotor helicopter to move laterally (right in our case) during hovering flight. Also called tail rotor drift. One way to fix this is by rigging the controls.
What are the four strokes of a reciprocating engine?
Intake
Compression
Ignition
Exhaust
List in order which aircraft has the right away over the others.
Airplanes balloons, rotorcraft, airship, gliders
Balloons Gliders Airships Airplanes Rotorcraft
What makes up he pitot static system?
Static port
Pitot tube/ ram air - ASI gauge
VSI gauge
AIT gauge
What are the VFR cruising altitudes when operating above 3,000 ft?
WEEO
West even numbers + 500 ft (4,500,6,500, 8,500)
East odd numbers + 500 ft (3,500, 5,500, 7,500)
