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| Aim:- |
To teach the correct technique for making a safe autorotative landing without the use of engine power |
Airmanship:-
- DO NOT DO THESE
- DUAL EXERCISE ONLY
But for training purposes and only ever with a qualified instructor...
- HASEL checks
- Choose area wisely - always onto licensed airfield
- Rotor RPM limits 90% - 110%
- At least 10Kts wind
- 10gals Max. fuel
- Wind direction
- Verbal warning - “Practice Autorotation - Go”
Air Exercises
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Circuit Height - 70 Kts, 700 ft, 20" MP |
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Governor to off |
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Line up with runway if possible but preferably into wind |
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Verbal Warning - “Practice Autorotation - Go” |
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Maintain 60 Kts to 65 Kts, RPM in green |
Committal Point - 200 ft - 300 ft
If Air speed 65Kts, RPM in Green, into Wind, Area OK.
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Fully close throttle into ‘Detent’ (Against over-travel spring) |
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At about 40ft start gentle cyclic flare - Max. Rotor RPM 110% |
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Make a progressive flare - control RRPM with collective if necessary |
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Flare reduces forward air speed and rate of descent |
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Maintain heading - right pedal |
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As aircraft starts to settle (6ft - 8ft) level skids and raise collective simultaneously to cushion ground contact - right pedal |
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On touchdown apply slight forward cyclic |
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On run-on keep aircraft straight with pedals |
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Wait for aircraft to stop before lowering lever |
Differences for ‘Flare-Power’ Recovery:-
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Do not close throttle into ‘Detent’ - Maintain ERPM @ about 80% |
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Start gentle cyclic flare @ about 50ft not 40ft |
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On levelling aircraft and bringing in collective (power) be ready with left pedal |
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Maintain forward speed with hover taxi - check RPM |
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If continuing with go-around - carb. heat in, lookout and radio call “Helicopter AL going around” - positive climb away |
Airspeed & Energy
The effect of the flare is dependent on airspeed - no airspeed no effect - there is very limited braking ability in collective alone.
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The graph shows the amount of energy available in HP (Horse Power) by virtue of the aircraft’s height (Potential Energy) and speed (Kinetic Energy).
HP Second (Horse Power Second) is a unit which represents the availability of this power over a period of time.
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R22 requires » 90HP to keep it in straight & level flight (90 Kts)
In autorotation @ 60 Kts power required » 60 HP
- See Power Required Curve.
With 60 Kts Forward Air Speed @ 40ft AGL:-
Kinetic Energy in main rotor
Potential Energy in 40 feet AGL
Kinetic Energy 60 Kts forward air speed
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approx 100 HP Secs
approx 100 HP Secs
approx 350 HP Secs
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Total Energy
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approx 550 HP Secs
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This equates to 550/60 approx 9 Secs to Ground contact.
With 30 Kts Forward Air Speed @ 40ft AGL:-
Kinetic Energy in main Rotor
Potential Energy in 40 feet AGL
Kinetic Energy 30 Kts Forward Air Speed
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approx 100 HP Secs
approx 100 HP Secs
approx 90 HP Secs
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Total Energy
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approx 290 HP Secs
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This equates to 290/60 approx 5 Secs to Ground contact.
Engine Off Landing from the Hover
Airmanship:-
- DO NOT DO THESE
- DUAL EXERCISE ONLY
But for training purposes and only ever with a qualified instructor...
- Good
- No more that 3ft skid height
- Choose area wisely - Flat surface & always onto licensed airfield
- Wind direction - Always into wind
- 10gals Max. fuel
- Avoid any sideways or backwards movement
- Verbal warning - “Practice Engine Failure - Go”
Introduce the student to these gradually, initially allowing use of only one control at a time
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Establish steady hover into wind - no more than 3ft skid height |
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Governor to off - check RPM |
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Verbal Warning - “Practice Engine Failure - Go” |
To simulate complete power failure
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Roll throttle fully closed against over-travel spring |
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Maintain direction - right pedal |
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Right cyclic to maintain position (correct for port drift) |
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As aircraft starts to settle simultaneously raise collective to cushion ground contact |
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On touchdown keep direction with pedals - avoid any sideways or backwards - Lower lever to secure ground contact |
To simulate partial power failure
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Close throttle enough to cause RPM and MP to decay |
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(Less yaw than complete power failure) maintain direction with pedals |
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Cyclic to maintain position |
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Allow aircraft to settle and cushion ground contact with collective - Roll throttle closed against over-travel spring to avoid increase in power. Careful attention to direction (correlator will cause increase in power if throttle not fully closed) |
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On touchdown keep direction with pedals - avoid any sideways or backwards - Lower lever to secure ground contact |
Discussion Points
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Use of Cyclic Flare |
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Cross wind & Downwind Autorotation |
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360° Autorotation |
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Engine Failure in the Hover |
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Partial Engine Failure in the Hover |
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Flare & Power recovery |
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Constant Attitude Straight Approach Autorotation |
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Effects of Weight - Heavier Ž Less Collective at Bottom End |
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Effects of Wind Velocity - Stronger Wind gives Lower ground speed |
Air Exercises
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EOL from the hover |
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Flare power recovery |
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EOL from circuit height |
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