propeller control unit (pcu) operation 10... · constant speeding variable pitch propeller system...
TRANSCRIPT
Constant Speeding Variable Pitch Propeller System
Propeller Control Unit (PCU) Operation
How the PCU changes propeller pitch and maintains constant engine speeds
The Pilot moves the throttle lever which, as well as changing fuel flow and therefore engine power, selects an RPM for the engine to run at.
The PCU maintains the selected speed by adjusting propeller pitch.
This eases pilot workload :-Especially during combat as the engine is automatically prevented from over speeding and therefore potential destruction and the pilot can concentrate on defeating the enemy
Basic Principal of Operation
And during civilian/transport duties giving the same engine safeguards as above allowing the pilot to concentrate on flying the aircraft, and therefore deliver the passengers and/or cargo safely to their destination
(You will see later that the throttle is connected to both the Fuel Control Unit and the PCU)
Propeller HubEngine Mounted
Simplified System
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Start& Idle
Cruise
Take Off
Throttle Positions: -
Pilot Input Signal
Hydraulic Pressure
Supply
Hydraulic Return
Operation Piston
Spinner
Connecting Linkage
Hydraulic Connections
PCU
Sliding Collar
Engine RPM Signal (Mechanical Drive)
Spring
Hydraulic Valve
Counter Balance Weights
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
FMU PCU
Piston Engine driven propeller
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
FMU PCU
Jet Engine driven propeller – Turbo-Prop
Propeller HubEngine Mounted
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Start& Idle
Cruise
Take Off
Throttle Positions
Pilot Input Signal
Engine Stationary
Propeller HubEngine Mounted
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Start& Idle
Cruise
Take Off
Throttle Positions
Pilot Input Signal
Start Initiated – Engine Begins to Rotate
Propeller HubEngine Mounted
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Start& Idle
Cruise
Take Off
Throttle Positions
Engine At Idle
Propeller HubEngine Mounted
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Start& Idle
Cruise
Take Off
Throttle Positions
Take Off Selected
Propeller HubEngine Mounted
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Start& Idle
Cruise
Take Off
Throttle Positions
Engine Accelerates to Take Off Speed
Propeller HubEngine Mounted
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Start& Idle
Cruise
Take Off
Throttle Positions
Engine Running at Take Off Speed
Flying straight and level
Flying straight and level
Look at how the PCU changes propeller pitch and maintains constant engine speeds during Dive commencement
In all these manoeuvres, all the pilot is doing is flying (redirecting) the aircraft, the throttle is not touched.
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
And then at Level Out
Propeller HubEngine Mounted
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Throttle Positions
Start& Idle
Cruise
Take Off
Aircraft Starts DiveThrottle (and Engine) at Cruise –
Propeller HubEngine Mounted
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Throttle Positions
Start& Idle
Cruise
Take Off
RPM IncreasesThrottle at Cruise –
Propeller HubEngine Mounted
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Throttle Positions
Start& Idle
Cruise
Take Off
RPM Increases - Prop Goes to Coarser PitchThrottle at Cruise –
Propeller HubEngine Mounted
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Throttle Positions
Throttle at Cruise –
Start& Idle
Cruise
Take Off
Aircraft in Dive – RPM Restored
Flying straight and level
Flying straight and level
Looked at how the PCU changes propeller pitch and maintains constant engine speeds during Dive commencement
In all these manoeuvres, all the pilot is doing is flying (redirecting) the aircraft, the throttle is not touched.
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Now at Level Out
Propeller HubEngine Mounted
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Throttle Positions
Throttle at Cruise –
Start& Idle
Cruise
Take Off
Aircraft Levels Out
Propeller HubEngine Mounted
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Throttle Positions
Start& Idle
Cruise
Take Off
RPM ReducesThrottle at Cruise –
Propeller HubEngine Mounted
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Throttle Positions
Start& Idle
Cruise
Take Off
Prop Pitch ReducesThrottle at Cruise –
Propeller HubEngine Mounted
PROPELLER SYSTEM – VARIABLE PITCH CONTROL
Throttle Positions
Start& Idle
Cruise
Take Off
RPM RestoredThrottle (and Engine) at Cruise –