Lecture 11 Flashcards
What are the parts of a helicopter?*
Rotor mast
Main rotor
Tail rotor
Cockpit
Vertical stabilizer
Landing skids
Engine and transmission
Where do the four forces act when a helicopter is in a hover?*
In directional flight?*
Thrust and lift act vertically up
Weight and drag act vertically down
Lift acts vertically up
Thrust acts in the direction the aircraft is flying
Weight acts vertically down
Drag acts opposite to the direction the aircraft is flying
What does the collective stick do when the pilot moves it?
Where is it located?
Pull up on the stick to go up
Push down on the stick to go down
On the pilot’s left side
What increases the lift of a helicopter when the collective stick is moved?
The increase in AOA of all of the main rotor blades collectively
Hint: collective, all move collectively
What does the cyclic stick do when the pilot moves it?
Where is it located?
Push forward to go forward
Pull back to slow down or fly backwards
Move/translate left to go left
Move/translate right to go right
In front of the pilot
What can pulling back on the cyclic stick be bad?
Rearward flight can cause the rotor blades to hit the tail boom, or cause the tail rotor to strike the ground
The _____ a helicopter tries to go forward, the further _____ the nose comes as more of the _____ effect is diverted from _____ and into _____.
faster
down
Bernoulli
lift
thrust
Describe how the cyclic stick changes blade pitch
Raises, lowers, or tilts the non-rotating plate
Rotating swash plate is correspondingly raised, lowered, or tilted
As the rotating swash plate is moved, the pitch change links that spin with the rotor blades, are also raised or lowered
This changes the pitch of the blades
What are the three parts of the rotor mast that change blade angle?
Pitch change links
Rotating swash plate
Non-rotating swash plate
The controls of a helicopter go through a device called a _____.
“Swash Plate”
Helicopter rotors run at a _____ in flight.
constant RPM
Why do main rotors turn at a constant RPM?
Increasing rotor speed to get more lift takes too long, changing the pitch gives instantaneous lift response
The rotor blades need centrifugal force to hold them out straight or else the lift forces will fold up or break the blades
Main rotor blades are very flexible, with no centrifugal force to hold them straight what will the blades do when not spinning?
Droop
Blades _____ when they are spinning and put under a lift load.
pull up, or “cone”
How do the blades on a helicopter remain straight?
The spinning rotor blades generate a centrifugal force that keeps the blades straight and prevents the blades from folding up or breaking
What is the force generated by spinning rotor blades?
What does the physics department call this force?
What does the FAA call this force?
Centrifugal force
Centripetal force
Centrifugal force
What does the tail rotor control?
What is it controlled by?
The direction the helicopter is facing
The pitch of the tail rotor
Controlled by the foot pedals or anti-torque pedals
What do the anti-torque pedals do when you push one?
How?
Push left pedal to face left
Push right pedal to face right
Changing the pitch of the tail rotor
What counteracts the torque of the spinning main rotor blade?
Tail rotor
What helps a helicopter fly straight?
How?
Tail rotor
Provides thrust in the opposite direction than the fuselage is trying to turn
What happens if the tail rotor quits?
Helicopter spins around in a circle in the opposite the direction of the main rotor
What is a Fenestron?*
An Aerospatiale helicopter with eleven blades in the tail rotor
Enclosed tail rotor greatly reduces injuries due to people running into tail rotors, and reduces accidents where tail rotors strike objects.
Over _____ of the noise and _____ of the injuries from helicopters come from _____.
60%
40%
tail rotors
What can greatly reduce noise and improve safety with helicopters?
Eliminating the tail rotor
What are some ways to eliminate the tail rotor?
NOTAR
Coaxial rotors
Tilt rotor
Tandem rotor
What is translating tendency?
A problem created by tail rotors
The sideways thrust of the tail rotor tries to drag the helicopter sideways
If uncorrected the helicopter drifts to the right
How do you fix translating tendency?
A design called “offset main rotor”
The rotor mast is attached at a slight angle to use some main rotor thrust to “offset” the tail rotor force
