LECTURE 2: ROTOR WING . A GENERAL APPROACH Oriol Lizandra i Dalmases Course 2013‐2014

(Anna typography, by courtesy of Anna Vives) TYPICAL DESGIGNS AND CONFIGURATIONS

2 Oriol Lizandra i Dalmases MAIN ELEMENTS OF A

Vertical Stabilizer

Blade Tail Rotor (anti‐torque)

Rotor Head

Tail Boom Horizontal Stabilizer

Fuselage and Cabin Skid

3 Oriol Lizandra i Dalmases FORCES ON A HELICOPTER

Rotor Lift Thrust

Propulsive force

Drag

Weight

4 Oriol Lizandra i Dalmases AgustaWestland AW109

5 EUROCOPTER AS350BA

6 MAIN ELEMEN TS OF AN AUT OGYRO

Right Vertical Left Vertical Stabilizer Horizontal Stabilizer Stabilizer

Right Tail Boom

Propeller

Rotor Head

Right Wing

Left Tail Boom

Fuselage and Cabin Blade

Left Wing Forward Gear Left Main Gear 7 Oriol Lizandra i Dalmases FORCES ON AN AUTOGYRO

T

F L D T : Rotor Thrust W W : Weight

L : Wing lift

D : Airframe drag

F : Propulsive force 8 Oriol Lizandra i Dalmases ELA 07S

9 GBA HAWK 4

10 GENERAL DESCRIPTION OF (CONVENTIONAAAL CONFIGURATION)

11 Oriol Lizandra i Dalmases HELICOPTER MAIN SYSTEMS • ENGINE/S: – Reciprocating engines, used in small helicopters (low power, say below 300 H.P.). – (gas turbine engine), with a much higher power‐weihight ratio. • TRANSMISSION SYSTEM: – Main rotor transmission. – Tail rotor transmission. – Clutch. – Free wheel unit. • MAIN (AND TAIL) ROTOR: – Swash plate. – Rotor head. – Blad es.

12 Oriol Lizandra i Dalmases TRANSMISSION SYSTEM MISSION: to transfer the output power from the engine to the main rotor and ttilail rotor, and is subdivided into: • MAIN ROTOR TRANSMISSION SYSTEM. Reduces the turn speed (with respect to that of the engine) to an optimum value for the main rotor. This reduction depends on the type and size of the helicopter. • TAIL ROTOR TRANSMISSION SYSTEM. Consist of a shfthaft ddiriven by the main ttiiransmission system and (in general) 2 gearboxes, the last one being placed at the end of the tail boom, permitting a 90 degrees change in the direction of the rotation axis, and also adjusting the turn speed according to the needs of the tiltail rotor (hig her rpm than in the main rott)or). 13 Oriol Lizandra i Dalmases • CLUTCH. Allows the engine to start up, reliev ing it from driving the rotor. It is only necessary in hlihelicopters ddiriven by eihither reciiiprocating engines or with no free (or power) turbine. – Centrifugal clutch. – Belt clutch. • FREE WHEEL UNIT. Allows the free turn of the rotor upon engine failure, so that this last doesn’t get driven by that. It is placed between the engine and the transmission system. A free wheel unit is required at the output shaft of each engine.

14 Oriol Lizandra i Dalmases MAIN TRANSMISSION SYSTEM

900 gearbox Tail rotor Main rotor transmission shaft Bearings mast

Intermediate 450 Main gearbox transmission Free wheel Clutch (1) unit Engine

(1): Only needed in some cases, such that helicopters driven by reciprocating engines or turboshaft with no free (power) turbine.

15 Oriol Lizandra i Dalmases 16 17 MAIN ROTOR SYSTEM • FULLY ARTICULATED ROTOR – Pitch hinge. – Flap hinge. – Lag hinge (also called lead‐lag hinge). • TEETERING ROTOR SYSTEM (two‐bladed rotors) – Pitch hinge. – Two blades attached to a teetering rotor head (with respect to the rotor mast). When a blade flaps up the other one flaps down. – No lag hinge. The blade flexibility at its root is what allows lag motion.

18 Oriol Lizandra i Dalmases • RIGID ROTOR HEAD SYSTEM – Only pitch hinge. – The blade flexibility at its root is what allows both flap and ldlead‐lag motions. • BEARINGLESS ROTOR SYSTEMS – Flap and lead‐lag hinges are replaced by flexures (elastomeric bearings) to accommodate blade motion. – Feathering hinges may exist or may be replaced by flexures. • ADVANCED ROTOR SYSTEMS (HINGELESS) – Hingeless rotor heads made of composites. No hinge is needed for either pitch, flap or lag motion. – The flexibili ty of the hbhub structure is what allows the three motions (bending, flexing and twisting). – Since there is no need for lubrication, less maintenance is required. In addition, vibrations are better absorbed, what in turn reduces fatigue and helicopter components’ life is improved.

19 Oriol Lizandra i Dalmases FULLY AAARTICULATED ROTOR SYSTEM

Rotor mast Flap hinge Pitch hinge Blade Lag hinge Blade chord

Lag damper Feathering axis (25% chord approx)

Blade length

Flap angle

20 Oriol Lizandra i Dalmases SWAHPATASHPLATE

Rotor mast

Rotating swashplate. It turns jointly with the rotor mast, it is mounted on bearings, remaining parallel to the stationary swashplate, and thus following its tilting and vertical motion. Pitch change rod

Stationary swashplate. It tilts in response of cyclic control inputs, and moves up and down with the inputs of the Control rods. Connected to the collective control. cyclic and collec tive contltrols.

21 Oriol Lizandra i Dalmases FULLY ARTICULATED ROTOR SYSTEM (Boeing AH‐64A Apache)

22 TEETERING ROTOR SYSTEM (BELL UH‐1D IROQUOIS)

23 TEETERING ROTOR SYSTEM WITH ADDITIONAL BLADE FLAPPING FREEDOM (ROBINSON R22)

24 RIGID ROTOR SYSTEM (EUROCOPTER Bo105M)

25 FLEXIBLE ROTOR SYSTEM WITH ELASTOMERIC BEARINGS (EUROCOPTER AS355)

26 HINGELESS ROTOR SYSTEM WITH FLEXIBLE BLADES (EUROCOPTER EC135)

27 ANTI-TORQUE SYSTEMS

28 Oriol Lizandra i Dalmases lt

 T

Ft

 Ft

PR M R M R  Ft   lt

T sin  Ft 29 Oriol Lizandra i Dalmases TWO‐BLADED TEETERING TAIL ROTOR

30 FOUR‐BLADED FLEXBEAM TAIL ROTOR

31 DUCTED TAIL ROTOR (FENESTRON)

32 DUCTED TAIL ROTOR (FENESTRON)

33 NOTAR SYSTEM

34 NOTAR SYSTEM

35 SPECIAL ROTORCRAFT CONFIGURATIONS

36 TANDEM COUTER‐ROTATING ROTORS (BOEING VERTOL CH‐47 CHINOOK)

37 COAXIAL COUNTER‐ROTATING ROTOR (KAMOV K‐32)

38 Reference bibliography

• FAA‐H‐8083‐21, Rotorcraft Flying Handbook • Wikipedia (pictu res). • Leishman, G., Principles of Helicopter Aerodynamics

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