PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.
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Transcript of PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.
![Page 1: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/1.jpg)
PROPELLER SYSTEMPROPELLER SYSTEM
1st - Look at how lift is generated
Then see how it applies to propellers
![Page 2: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/2.jpg)
How lift is generated
PROPELLER SYSTEM
![Page 3: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/3.jpg)
In this example
Pressure Remains Constant here
Pressure Decreases hereIn this direction
The result is LIFT
How lift is generated
PROPELLER SYSTEM
![Page 4: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/4.jpg)
Small Pressure Increase here
Greater Pressure Decrease here
The result is
MORE LIFT
How lift is increased
PROPELLER SYSTEM
![Page 5: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/5.jpg)
Direction of travel
Aerofoil incline
The difference in direction of travel and aerofoil incline is called:-
The ANGLE of ATTACK
How lift is increased
PROPELLER SYSTEM
![Page 6: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/6.jpg)
How does lift apply to PROPELLORS?
On Propellers, LIFT is called THRUST
And propeller Blades work the same way as aircraft wings
When a propeller spins and the aircraft moves forward, the tips of the propeller blades move in a ‘corkscrew’ path
This path is called a HELIX
PROPELLER SYSTEM
![Page 7: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/7.jpg)
How the HELIX ANGLE is generated
![Page 8: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/8.jpg)
How the blade tip travel produces the HELIX ANGLE
PROPELLER SYSTEM
![Page 9: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/9.jpg)
How the blade tip travel produces the HELIX ANGLE
PROPELLER SYSTEM
![Page 10: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/10.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 11: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/11.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 12: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/12.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 13: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/13.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 14: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/14.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 15: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/15.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 16: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/16.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 17: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/17.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 18: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/18.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 19: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/19.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 20: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/20.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 21: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/21.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 22: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/22.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 23: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/23.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 24: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/24.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 25: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/25.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 26: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/26.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 27: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/27.jpg)
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 28: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/28.jpg)
How the blade tip travel produces the HELIX ANGLE
PROPELLER SYSTEM
Forward Speed - Distance Travelled over One Minute
Rotation - Number of Rotations per Minute
![Page 29: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/29.jpg)
Forward Speed
RPM
How the blade tip travel produces the HELIX ANGLE
PROPELLER SYSTEM
![Page 30: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/30.jpg)
PROPELLER SYSTEM
Forward Speed
RPM
How the blade tip travel produces the HELIX ANGLE
![Page 31: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/31.jpg)
Forward Speed
RPM
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 32: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/32.jpg)
Forward Speed
RPM
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 33: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/33.jpg)
Forward Speed
RPM
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 34: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/34.jpg)
Forward Speed
RPM
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 35: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/35.jpg)
Forward Speed
RPM
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 36: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/36.jpg)
How the HELIX ANGLE is changed by engine rpm and forward speed
![Page 37: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/37.jpg)
Forward Speed
RPM
How an increase in RPM changes the Helix Angle
Changes in FORWARD SPEED and RPM will change the Helix Angle
Faster RPM
PROPELLER SYSTEM
How the blade tip travel produces the HELIX ANGLE
![Page 38: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/38.jpg)
Forward Speed
RPMRPM
Faster Forward Speed
Changes in FORWARD SPEED and RPM will change the Helix Angle
How an increase in FORWARD SPEED changes the HELIX ANGLE
PROPELLER SYSTEM
![Page 39: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/39.jpg)
Let’s take a closer look at the blade aerofoil and the Helix Angle and thrust (lift) generation
If the Helix Angle changes, then we need to change the
blade angle.
Remember (from the comparison with the aircraft wing), the optimum Angle of Attack is required to maintain most efficient thrust generation.
This is the Helix Angle
This is the Angle of AttackDirection of
rotation
Direction of blade through the air with forward speed
PROPELLER SYSTEM
![Page 40: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/40.jpg)
Mechanical STOPS and blade angles
![Page 41: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/41.jpg)
All propeller blades are actuated by the same mechanical linkage
PROPELLER SYSTEM
Sliding Piston
Hard Stops
Fine Pitch
Coarse Pitch
Direction of
Rotation
Direction of Flight
Propeller Blade
Actuating Lever
Actuating Link
![Page 42: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/42.jpg)
Note: - blade angle is relative to piston travel
Fine pitchCoarse pitch
Or
‘Feathered’
Piston travels between ‘hard’ stops
Direction
Of
Rotation
Maximum resistance to rotation
Minimum resistance to forward
speed
Minimum resistance to
rotation
Maximum resistance to forward
speed
The blade angle changes through 90deg with piston travel
At this hard stop the blade is in this
position
At this hard stop the blade is in this
position
PROPELLER SYSTEM
![Page 43: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/43.jpg)
Easier Starting of engine
Direction of travel
Direction of Rotation
Good for:-
Running engine with no/minimal thrust
Bad for:-
In-flight – loss of control
High drag – braking effect on ground
Zero pitch – or Ground Fine Pitch
In-flight engine failure – loss of control andengine disintegration
PROPELLER SYSTEMImportance of set blade angle
Fine pitch
Minimum resistance to
rotation
Maximum resistance to forward
speed
![Page 44: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/44.jpg)
Maximum resistance to rotation
Minimum resistance to forward
speed
Starting of engine
Direction of travel
Direction of Rotation
Bad for:-
Could cause engine burn-out if running
Low drag – NO braking effect on ground
Maximum pitch – or Feathered
Good for:-
In-flight – loss of control
In-flight engine failure – control maintained and engine stops rotating minimizing damage
PROPELLER SYSTEMImportance of set blade angle
![Page 45: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/45.jpg)
Minimal resistance to
rotation
Air pushed forward giving reverse thrust
Direction of travel
Direction of Rotation
Used for:-
Bad for:-
In-flight – loss of forward speed, aircraft stalls
High drag – high braking effect on ground
Reverse Pitch
In-flight engine failure – loss of control and reverse rotation increasingengine disintegration
Usually for military aircraft only
PROPELLER SYSTEMImportance of set blade angle
![Page 46: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/46.jpg)
Direction of travel
Direction of Rotation
Used for:-
Low drag on final approach
Flight Fine and Cruise Pitch
Used for:-
In-flight descent – faster forward speed thanfinal approach
Flight Fine pitch
Cruise pitch
Both give minimal drag at low power settings
PROPELLER SYSTEMImportance of set blade angle
![Page 47: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/47.jpg)
Blade Twist
![Page 48: PROPELLER SYSTEM 1 st - Look at how lift is generated Then see how it applies to propellers.](https://reader030.fdocuments.in/reader030/viewer/2022032806/56649f065503460f94c1b5f5/html5/thumbnails/48.jpg)
DISTANCE TRAVELLED BY DISTANCE TRAVELLED BY ROOT, MID-SPAN AND TIPROOT, MID-SPAN AND TIP
THICK FOR THICK FOR STRENGTHSTRENGTH
PROPELLER SYSTEMBlade Twist
ROOT MID-SPAN TIP
THINNER FOR THINNER FOR STRENGTH AND STRENGTH AND
THRUSTTHRUST
THIN FOR THIN FOR THRUSTTHRUST
COARSE ANGLE
MEDIUM ANGLE
FINE ANGLE
BLADE ANGLE RELATIVE TO DISTANCE (AND THEREFORE SPEED) BLADE ANGLE RELATIVE TO DISTANCE (AND THEREFORE SPEED) TRAVELLED BY ROOT, MID-SPAN AND TIPTRAVELLED BY ROOT, MID-SPAN AND TIP
Typical Blade
Typical 3 Blade Prop