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RC Helicopter Mechanism

RC Helicopter Mechanism. Sylvain Marron. 1: Mechanism. Clutch Main Gear Tail Rotor Drive Swash Plate. Clutch. Purpose: to start the engine without driving the rotor safety It is a centrifugal clutch: main rotor is driven when engine accelerates

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RC Helicopter Mechanism

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  1. RC Helicopter Mechanism Sylvain Marron

  2. 1: Mechanism • Clutch • Main Gear • Tail Rotor Drive • Swash Plate

  3. Clutch • Purpose: to start the engine without driving the rotor • safety • It is a centrifugal clutch: • main rotor is driven when engine accelerates • main rotor is not driven when engine idles

  4. Main Gear • Purpose: to drive the main rotor • A tail drive pulley is mounted just below • This assembly is mounted on a one way bearing: • when the engine runs it drives the rotor • when the engine idles or stops, the main rotor turns freely

  5. Tail rotor drive • Belt drive • Torque tube drive

  6. Tail rotor drive: Comparison test

  7. Swash Plate • Purpose: to transmit orders to main rotor • moves Up/Down → collective pitch control • tilts → cyclic pitch control • There are many swash plate types: • swash plate type defines the layout and the number of servos which operate the collective pitch function • swash plate type may differ according to the model and the manufacturer

  8. Swash plate types • H1 → 1 servo for collective pitch • H2 → 2 servos for collective pitch • H3 → 3 servos (2 nick) • H3 → 3 servos (2 roll) • named 120° CCPM, widespread • H4 → 4 servos 90° (2 nick / 2 roll)

  9. Swash plates: Comparison test

  10. 2: Electronics • Governor • Gyroscope • Flybarless system

  11. Governor • The governor automatically maintains constant rotor RPM • Operating: • a sensormeasuresengine speed • the governor controls the throttle servo (and sometimes mixture) • Connections: Throttle servo Magnetic sensor Mixture servo Governor Speed Mixture Throttle Receiver

  12. Gyroscope • Assists the pilot for rudder control • Holds a specific heading regardless of conditions: • torque variations • cross-wind • Without gyroscope: Wind • With head lock gyroscope (or Head Hold): Wind

  13. Connecting the gyroscope Gain Rudder control Receiver Gyroscope Rudder servo • The gyroscope detects an angular velocity • Gain allows to set the gyroscope sensitivity

  14. Gyroscope Operating • Gyroscope compensates for unexpected tail drift Gain Gain Rudder control Rudder control Receiver Receiver Gyroscope Gyroscope Rudder servo Rudder servo • Command sent by pilot Transmitter

  15. Flybarless System • Flybarless = without flybar • Electronic management • →3-axis gyroscope: • controls all functions ! (except throttle) Flybarless Module Servos Roll Nick Gain Rudder Pitch Pitch Cyclic Nick Roll Receiver Rudder

  16. Comparison test • Flybarless rotor • Rotor with flybar

  17. 3: Electric Helicopters • Nowadays electric helis are as powerful as nitro helis • Brushless motors + LiPo batteries = Revolution • Light weight (for small and average models)

  18. Equipment • 1 brushless motor (powerful, high current) • 1 ESC Electronic Speed Controller (high current) • built-in governor • LiPo batteries (high discharge current)

  19. Classes • 700 : 700mm blades (= 90-size nitro model) • 600 : 600mm blades (= 50-size nitro model) • 550 : 550mm blades (= 30-size nitro model) • 500 : 425mm blades • 450 : 325mm blades • 250 : 205mm blades

  20. Electric vs. Nitro

  21. The End You can find this PowerPoint and other information on my website : http://mvlys.free.fr/HelicoRC/index.htm

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