Guimbal Cabri down at Kemble
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I appreciate Guimbal's explanation, but once you get beyond the sales pitch, he said in so many words "pilot error." We've seen the same from other light, two-seat helicopter manufacturers.
I would like to have seen him add more details of the event: Wind was at "X" knots from "Y" radial, pilot was transitioning / taxying / pedal turning in hover, etc.
He says the pilot lost yaw control while hovering, then had a hard landing. Did the pilot dump collective when things went pear shaped? More details might have helped new pilots better understand the ship's flight characteristics.
I wonder if the authorities have come to the same conclusion as the manufacturer?
But good on him for recognizing some deficiencies in the training program and implementing changes. Seems a sturdy little ship, good to see competition in the marketplace.
I would like to have seen him add more details of the event: Wind was at "X" knots from "Y" radial, pilot was transitioning / taxying / pedal turning in hover, etc.
He says the pilot lost yaw control while hovering, then had a hard landing. Did the pilot dump collective when things went pear shaped? More details might have helped new pilots better understand the ship's flight characteristics.
I wonder if the authorities have come to the same conclusion as the manufacturer?
But good on him for recognizing some deficiencies in the training program and implementing changes. Seems a sturdy little ship, good to see competition in the marketplace.
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Birddog
I am not a CPL and compared to many guys here my hours are low. Here is my view, but I welcome any more experienced PPrune member to correct / improve.
The rapid accellaration of yaw effect can be generated in gusty conditions or it can simply be a result of turning through the wind thoughtlessly. It actually happens to some degree on every turn to the left, even in mild wind, but mild wind = smaller additional torque force hence small accelaration. Control is simple, though the distance that you need to move your right foot can catch out somone unused to the machine. Practicing left turns in (first) little wind and (then) slightly increased winds (and stopping before the wind strength means that you do something daft) will show you the effect, and how the yaw rate effect increases with increasing windspeed.
Turning left through a high wind brings significant additional torque load onto the tail due to the sail area. Accelaration in yaw can be high; literally "stunningly so" for some people in some conditions. If your mind is not ahead of the aircraft (if it was, why were you turning left through the wind in an EC120 / Gazell / Guimbal / etc?) it may startle you and your reaction may be slow; perhaps some people even freeze. The accellaration in yaw is rapid. It can reach a sufficient rate of yaw (before your control inputs begin to have any effect) to buld the momentum to take the machine through a full rotation - weather-cocking and your right boot will bring it to a halt but it may not be until the 2nd or 3rd full rotation if your reaction to the initial yaw is not quick enough. During that time your job is to keep it level and away form the ground / other expensive objects. Not as easy as it sounds with a rotation rate that might have reached 30+ RPM.
Training mantra "To the right, avoids a fright" is best followed. Don't use a left turn unless you have considered the wind direction and strength, remaining power available, and when to begin the anticipatory right boot movement (it is best to be increasing the right boot before you put the tail through the wind).
The aircraft is perfectly manageable; it just requires that you understand its characterisics and limitations and fly accordingly. Personally, you may never get me out of this model; except into a Guimbal once I cannot afford the EC120.
I am not a CPL and compared to many guys here my hours are low. Here is my view, but I welcome any more experienced PPrune member to correct / improve.
The rapid accellaration of yaw effect can be generated in gusty conditions or it can simply be a result of turning through the wind thoughtlessly. It actually happens to some degree on every turn to the left, even in mild wind, but mild wind = smaller additional torque force hence small accelaration. Control is simple, though the distance that you need to move your right foot can catch out somone unused to the machine. Practicing left turns in (first) little wind and (then) slightly increased winds (and stopping before the wind strength means that you do something daft) will show you the effect, and how the yaw rate effect increases with increasing windspeed.
Turning left through a high wind brings significant additional torque load onto the tail due to the sail area. Accelaration in yaw can be high; literally "stunningly so" for some people in some conditions. If your mind is not ahead of the aircraft (if it was, why were you turning left through the wind in an EC120 / Gazell / Guimbal / etc?) it may startle you and your reaction may be slow; perhaps some people even freeze. The accellaration in yaw is rapid. It can reach a sufficient rate of yaw (before your control inputs begin to have any effect) to buld the momentum to take the machine through a full rotation - weather-cocking and your right boot will bring it to a halt but it may not be until the 2nd or 3rd full rotation if your reaction to the initial yaw is not quick enough. During that time your job is to keep it level and away form the ground / other expensive objects. Not as easy as it sounds with a rotation rate that might have reached 30+ RPM.
Training mantra "To the right, avoids a fright" is best followed. Don't use a left turn unless you have considered the wind direction and strength, remaining power available, and when to begin the anticipatory right boot movement (it is best to be increasing the right boot before you put the tail through the wind).
The aircraft is perfectly manageable; it just requires that you understand its characterisics and limitations and fly accordingly. Personally, you may never get me out of this model; except into a Guimbal once I cannot afford the EC120.
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John R81, brilliant post! In short dont critisise what you dont yet understand. Understand the fenestron and she is your best friend no matter the type-fly it like a tail rotor good luck!
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Fenestron control
Hi helihub and John,
I tried, let the G2 turn non power pedal 270 deg letting go of the pedal then put in full opposite pedal. The turn stopped, but only after a scary 120 deg! The fenestron did not stall, which is very good, but it took far too long to stop the turn. Imagine the same situation at 5000ft... Right, Bruno says a lot, but certainly not all.
I tried, let the G2 turn non power pedal 270 deg letting go of the pedal then put in full opposite pedal. The turn stopped, but only after a scary 120 deg! The fenestron did not stall, which is very good, but it took far too long to stop the turn. Imagine the same situation at 5000ft... Right, Bruno says a lot, but certainly not all.
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Turning with Fenestron
Echo...Good Post John..when I turn left in the 120 it is more ease of pressure on right pedal rather than any positive input on left pedal...and slow 
If she goes around, stay level and get away from the ground
If she goes around, stay level and get away from the ground
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Torque reaction.
'Training mantra "To the right, avoids a fright" is best followed.'
This depends on whether the blades turn clockwise or anti clockwise doesn't it?
Left pedal turns in a anti clockwise rotating helicopter require more power than right turns but in an aircraft with blades turning the other way the opposite is true is it not?
Do they turn clockwise or anti clockwise in the Cabri?
This depends on whether the blades turn clockwise or anti clockwise doesn't it?
Left pedal turns in a anti clockwise rotating helicopter require more power than right turns but in an aircraft with blades turning the other way the opposite is true is it not?
Do they turn clockwise or anti clockwise in the Cabri?
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Equipment
It does have a governor, and a very complete basic equipment list:
BASIC EQUIPMENT
Electronic CDI ignition
Smart engine governor
Two-axis electric trim with pilot & copilot control
High-energy crash-certificated stroking seats
Disc rotor brake
Four-points harnesses with inertia reel
Cabin heater
Keyless entry and starting lock
Fast – removal copilot controls
Handling wheels
Removable customized cabin flight bag
Multi-function vehicle & engine display :
Electronic CDI ignition
Smart engine governor
Two-axis electric trim with pilot & copilot control
High-energy crash-certificated stroking seats
Disc rotor brake
Four-points harnesses with inertia reel
Cabin heater
Keyless entry and starting lock
Fast – removal copilot controls
Handling wheels
Removable customized cabin flight bag
Multi-function vehicle & engine display :
Smart power indicator
High precision capacitive fuel gage
Fuel flow with displays :
High precision capacitive fuel gage
Fuel flow with displays :
- Flight time remaining
- Instant fuel flow
- Average fuel flow
- Average fuel flow
Self-closing electrical magnetic
plugs – MGB & TGB
Automatic carburetor heater
Carbon monoxide detector
Flight time counter
Flight log
Stopwatch
Complete engine monitor
Carbon monoxide detector
Flight time counter
Flight log
Stopwatch
Complete engine monitor
A very interesting aircraft, I can't wait to try one myself
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Hi JW, Cabri & EC120 main rotors turn clockwise so right torque pedal..
You are right re: anti-clockwise, though on types I have flown (H500, CBi300, E480), I have not experienced such a pronounced effect on right turns in wind. Positive left pedal action in the 120 (even in light wind) can catch you out.
From the EC & Helicoptersafety websites:
Clockwise: http://www.eurocopter.com/site/docs_...73-67-04en.pdf
Anti-clockwise: http://www.helicoptersafety.org/pdfs/1692-67-04en.pdf
You are right re: anti-clockwise, though on types I have flown (H500, CBi300, E480), I have not experienced such a pronounced effect on right turns in wind. Positive left pedal action in the 120 (even in light wind) can catch you out.
From the EC & Helicoptersafety websites:
Clockwise: http://www.eurocopter.com/site/docs_...73-67-04en.pdf
Anti-clockwise: http://www.helicoptersafety.org/pdfs/1692-67-04en.pdf
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Unless the governor incorporates a yaw rate sensor, anytime you have a rapid yaw rate, you'll have an effect on rotor RPM that will not be what you'd expect. In fact, it will be the opposite of what would happen without a governor.
In the Cabri, if you're yawing with the direction of rotation of the main rotor, you'll climb (if you don't touch the collective). If you're yawing counter to the direction of rotation, you'll descend, and it may be difficult to stop the descent.
Think about the governor as counting rotor blades passing over the tail boom. It wants to keep that constant, and so if you're yawing with the rotor, the governor will think the rotor has slowed down. It adds fuel to get the rotor back to the 'correct' rate of rotation, but this is actually faster with respect to the earth than it appears from within the frame of reference of the helicopter. Hence the climb.
Opposite if you're yawing counter to the direction of rotation.
Could be part of the explanation for the incident.
In the Cabri, if you're yawing with the direction of rotation of the main rotor, you'll climb (if you don't touch the collective). If you're yawing counter to the direction of rotation, you'll descend, and it may be difficult to stop the descent.
Think about the governor as counting rotor blades passing over the tail boom. It wants to keep that constant, and so if you're yawing with the rotor, the governor will think the rotor has slowed down. It adds fuel to get the rotor back to the 'correct' rate of rotation, but this is actually faster with respect to the earth than it appears from within the frame of reference of the helicopter. Hence the climb.
Opposite if you're yawing counter to the direction of rotation.
Could be part of the explanation for the incident.
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Shawn, does the governor actually measure rpm relative to the fuselage or does it work on absolute rpm?
You don't by any chance ahve any relations/ancestors from Donegal in Ireland? Coyle is a pretty common name there.
You don't by any chance ahve any relations/ancestors from Donegal in Ireland? Coyle is a pretty common name there.
