2-Fundamentals of rotor aerodynamics 2013 [Modo … / Filipe Szolnoky Cunha Fundamentals of rotor...

Helicopters / Filipe Szolnoky CunhaSlide 1Fundamentals of rotor aerodynamics

Airplane


Fundamentals of rotor

aerodynamics

•The rotor provides 3 basic functions

•Generation of lift

•Generation of trust

•Control the attitude and position



aerodynamics

Azimuth

Angle

V Forward

velocity

ψ

Ψ=0

Ψ=90Advancing

Side

Ψ=180

Retreating

SideΨ=270


Rotor

rotation

speed Ω

Velocity

Perpendicular

to the blade


aerodynamics

Velocity in

hover



aerodynamicsVelocity in

Forward

Flight



aerodynamics

• Velocity distribution is not

uniform

• Generation of lift is asymmetric



aerodynamicsTo compensate de asymmetry

• It’s necessary to change the blade AOA (lower on

the advancing side, higher on the retreating side)



aerodynamics• To avoid high moments due to the blade on

the rotor hub the blade is allowed to flap



aerodynamics• To allow the blades movement at constant

velocity the blade is allowed to lag



aerodynamics• The blade can have three movements:

- Flapping (β) - Feathering (θ) - Lagging (ζ)



aerodynamicsRotor



aerodynamicsThis changes are cyclical->The Swashplate



aerodynamics

The rotor Hub


Balancing the torque

• For each action there is an equal and opposite

reaction.

• A torque is applied to the rotor to maintain it

rotating. The rotor applies an opposite torque

to the fuselage.

• To stabilize the fuselage an anti-torque is

necessary.



Typical configuration: Main rotor/tail rotor



Co-Axial configuration: two main rotors on the

same shaft



Tandem: Two main rotors fore and aft


Controls

• Cyclic control: cyclic stick

– Changes the main rotor tilt and therefore

changes the direction of the propulsion


Controls

Cyclic control :


Controls

• Collective control: collective lever, ( left side)

– The collective changes the pitch angle at the same

time and independent of the position.


Controls

Collective control :


Controls

• Yaw control: Anti-torque pedals

– Changes the tail rotor propulsion


Controls

Yaw control:

:


• Motors VS rotors?


Manoeuvring

What you can´t (can) do with an helicopter


Wake

Wake velocity



aerodynamics

The problems are many

2-Fundamentals of rotor aerodynamics 2013 [Modo … / Filipe Szolnoky Cunha Fundamentals of rotor...

Documents

Transcript of 2-Fundamentals of rotor aerodynamics 2013 [Modo … / Filipe Szolnoky Cunha Fundamentals of rotor...