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-   -   Guimbal Cabri G2 (https://www.pprune.org/rotorheads/296022-guimbal-cabri-g2.html)

[email protected] 25th Apr 2019 16:48

Nugget - sadly, no I don't have a copy of that video, sorry.

Hot and Hi 25th Apr 2019 16:54


Originally Posted by Robbiee (Post 10454899)
Well the F280C I flew was pretty easy to fly and built like a tank,...and that was 13 years ago. So just how "early" you talkin' 'bout?

I also learned in a Shark. No issues here. Taught me how to work the throttle and the kuli hat. Prepared me well for the MD500 (the kuli hat that is). Although I found that due to the generally stiff controls in the Cabri, the kuli hat operation feels very different in the Cabri compared to Enstrom (all models) or MD500.

But we are digressing ...

Hot and Hi 25th Apr 2019 17:00


Originally Posted by Bell_ringer (Post 10455602)
A 22 is somewhat lighter, you can operate a 22 hot and hi, you can't in a cabri. Heavy and low power isn't a good combo.

It is also assumed that - all things equal - a Fenestron uses twice the power compared to a traditional tail rotor. In the hover this can easily exceed 20% of the power produced by the engine (vs 10% in a R22).

The experts will have more accurate figures. But by any standards, that's a lot of power that is not available for lift.

Robbiee 25th Apr 2019 18:29


Originally Posted by Hot and Hi (Post 10455729)
It is also assumed that - all things equal - a Fenestron uses twice the power compared to a traditional tail rotor. In the hover this can easily exceed 20% of the power produced by the engine (vs 10% in a R22).

The experts will have more accurate figures. But by any standards, that's a lot of power that is not available for lift.

Seems like the fenestron is not the best choice for a small underpowered trainer? Anyone know why Bruno chose it over a more traditional tail rotor?

[email protected] 25th Apr 2019 20:53

It's a similar size to the Gazelle one but with far fewer blades.

Perhaps chosen for safety - no TR strikes with a fenestron.

Robbiee 25th Apr 2019 23:19


Originally Posted by [email protected] (Post 10455887)

Perhaps chosen for safety - no TR strikes with a fenestron.

I don't know, seems to me if you're spinning around uncontrollably the tail's gonna strike something, eventually.:ok:

aa777888 26th Apr 2019 03:03


Originally Posted by Robbiee (Post 10455793)
Seems like the fenestron is not the best choice for a small underpowered trainer? Anyone know why Bruno chose it over a more traditional tail rotor?

I suspect because he wanted the G2 to be a trainer with a focus on a path to the Airbus line of fenestron equipped helicopters, and because he probably feels that the safety and noise advantages outweigh any disadvantages in performance or handling characteristics.

On the former issue that seems quite smart. On the latter issue I find myself in disagreement.

P.S. Hot and Hi: it's "coolie hat", just Google it ;) I also found it somewhat difficult to use effectively. There is so much friction in the G2 control system that you have to rely more on timing than feel to get the trim where you want it.

Hughes500 26th Apr 2019 05:41

Robbie

My apologies meant an F28A not a 280, no power what so ever !!!! With a true manual throttle and mechanical clutch lever !!!!

AMDEC 26th Apr 2019 10:50


Originally Posted by Robbiee (Post 10455793)
Seems like the fenestron is not the best choice for a small underpowered trainer? Anyone know why Bruno chose it over a more traditional tail rotor?

Loss of control in yaw is not specific to the fenestron. I looked into accident reports coming from different Aviation Investigation Boards. Between 2010 and 2016 (seven years) I have 9 on the Cabri, 26 on the R22, 26 also on the R44 and I am afraid I missed some...

My feeling is that a helicopter type involved in basic training is taking some risks.

Robbiee 26th Apr 2019 19:36


Originally Posted by AMDEC (Post 10456279)
Loss of control in yaw is not specific to the fenestron. I looked into accident reports coming from different Aviation Investigation Boards. Between 2010 and 2016 (seven years) I have 9 on the Cabri, 26 on the R22, 26 also on the R44 and I am afraid I missed some...

My feeling is that a helicopter type involved in basic training is taking some risks.

Surprised to hear that about the R22. As a student I found the pedals to be the easiest and quickest to learn,...even did my first slope landings in 13 kts winds without losing it. Oh well :(

Robbiee 26th Apr 2019 19:39


Originally Posted by Hughes500 (Post 10456051)
Robbie

My apologies meant an F28A not a 280, no power what so ever !!!! With a true manual throttle and mechanical clutch lever !!!!

Ha! Yeah, that clutch lever is something! At Heliexpo about a year ago I noticed they still use that design. :ooh:

Cyclic Hotline 27th Apr 2019 04:17

Machine down in McMinville, Oregon
 
https://www.koin.com/news/crashes/2-...ash/1958257725

KNIEVEL77 27th Apr 2019 08:04


Originally Posted by Cyclic Hotline (Post 10456886)

Im not sure what this has to do with the Cabri?

Carbon Bootprint 27th Apr 2019 13:08


Originally Posted by KNIEVEL77 (Post 10456981)


Im not sure what this has to do with the Cabri?

Perhaps because that was the type involved?

https://newsregister.com/article?articleId=33031

KNIEVEL77 27th Apr 2019 14:25


Originally Posted by Carbon Bootprint (Post 10457196)
Perhaps because that was the type involved?

https://newsregister.com/article?articleId=33031

Ah I apologise the report I saw stated it was a Robinson, at least yet another accident without fatalities!


WillyPete 27th Apr 2019 23:47

I enjoy flying the Cabri.
Yes, the Fenestron and right pedal action takes a bit of getting used to when transitioning from types like the R22 and 44, but it is not difficult. Like learning how to drive a manual car with a "late" clutch pedal effect, rather than a large soft zone of effect.

Things that were driven home early on were "More right pedal!" when coming to the hover, and to always perform your turns in the hover to the right.
There's too much danger in letting the aircraft get away from you if you turn to the left.
Bringing the nose back from too much right pedal is not simply a matter of pushing on the left, it's easier to describe it as releasing the right pedal pressure.
Even in the R22 it's sensible to turn against the torque.

I've chosen to practise airfield manoeuvres in the hover during 20+ knot winds, to get to know the aircraft and my own skills better. It handles absolutely fine in strong winds, but the pilot needs to be aware of the influence of that massive tail and shroud when the wind gusts or you have to make a turn into a tailwind.
We practised 360 turns around a point and yes, having a tail pointing directly into the wind takes all of your concentration. It's massive compared to the R22 tail.
As you pass the point where the wind switches sides of the tail, it can and will grab suddenly and you have to be on top of it - ready to stomp the right pedal. Dicking about with the collective at that point will definitely add or remove some yaw to the equation.

I never felt at any point that there was a loss of authority for such an "underpowered" helicopter as some have called it. Absolutely no evidence of any of the fabled "fenestron stall".
A few times I had to use almost full deflection of the right pedal to hold it there, but we never lost it even in such a relatively high wind for a trainer.
I've been at schools that ground you in the R22 at lesser wind speeds.
It's all up to the pilot to practise and be aware of their own limitations as well as those of the aircraft. From my limited time in it, and experience flying, it's hard to imagine it's a flawed design when it behaves properly within recommended handling guidelines.

"I have to fly it differently than my other types" is not a design flaw.

The article does list several accidents due to uncontrolled yaw, but when you look at them and the circumstances leading up to it you have to ask - would a conventional tail rotor deliver a different, safer result? If the answer is yes, then the design is not flawed but instead has "vulnerabilities" that should be avoided.

Triple Nickel 8 Ball 29th Apr 2019 13:51


Originally Posted by WillyPete (Post 10457627)
I enjoy flying the Cabri.
Yes, the Fenestron and right pedal action takes a bit of getting used to when transitioning from types like the R22 and 44, but it is not difficult. Like learning how to drive a manual car with a "late" clutch pedal effect, rather than a large soft zone of effect.

Things that were driven home early on were "More right pedal!" when coming to the hover, and to always perform your turns in the hover to the right.
There's too much danger in letting the aircraft get away from you if you turn to the left.
Bringing the nose back from too much right pedal is not simply a matter of pushing on the left, it's easier to describe it as releasing the right pedal pressure.
Even in the R22 it's sensible to turn against the torque.

I've chosen to practise airfield manoeuvres in the hover during 20+ knot winds, to get to know the aircraft and my own skills better. It handles absolutely fine in strong winds, but the pilot needs to be aware of the influence of that massive tail and shroud when the wind gusts or you have to make a turn into a tailwind.
We practised 360 turns around a point and yes, having a tail pointing directly into the wind takes all of your concentration. It's massive compared to the R22 tail.
As you pass the point where the wind switches sides of the tail, it can and will grab suddenly and you have to be on top of it - ready to stomp the right pedal. Dicking about with the collective at that point will definitely add or remove some yaw to the equation.

I never felt at any point that there was a loss of authority for such an "underpowered" helicopter as some have called it. Absolutely no evidence of any of the fabled "fenestron stall".
A few times I had to use almost full deflection of the right pedal to hold it there, but we never lost it even in such a relatively high wind for a trainer.
I've been at schools that ground you in the R22 at lesser wind speeds.
It's all up to the pilot to practise and be aware of their own limitations as well as those of the aircraft. From my limited time in it, and experience flying, it's hard to imagine it's a flawed design when it behaves properly within recommended handling guidelines.

"I have to fly it differently than my other types" is not a design flaw.

The article does list several accidents due to uncontrolled yaw, but when you look at them and the circumstances leading up to it you have to ask - would a conventional tail rotor deliver a different, safer result? If the answer is yes, then the design is not flawed but instead has "vulnerabilities" that should be avoided.


I could not agree more with all of this. I've come from a fixed wing background (and "do fixed wing" for a living...) and have recently qualified in the Cabri. I learned a valuable lesson with a superb instructor re the correct pedal input. I've told the story somewhere here before, but in brief, I approached a confined area into wind. A fairly steady 12-15 knots was present and, as we had to turn DOWNWIND for the actual landing (the IP did enjoy making me work on the pedals during downwind hovering), so we could land upslope, for some reason, known only to my sub conscience, I elected to turn LEFT and not RIGHT. All was fine, feeling it around slowly, when the wind took the tail and WHOOSH....we were off at a decent rate of "spin". The IP grabbed it straight away with the standard "I have control (and in his head...."YOU IDIOT!")!" and he sorted it out with a SHED load (nearly all of it?) of right pedal and got us straightened out and immediately gave it back to me to land.

When it first happened, I genuinely thought that the tail rotor had failed or something. I was like a rabbit in headlights.......however, NOW....I think I would recognise the signs of it....and will ALWAYS turn RIGHT in the hover. Actually, if I had turned LEFT very gingerly, and NOT with the same kind of input/pedal speed as I would when turning right, it would probably have been okay.

Overall, the Cabri is an amazing little helicopter (and don't forget....it's a "TRAINER", that was really designed for its UAV capability/military applications).

Roll on the Turby 5 seater!

aa777888 29th Apr 2019 14:48

And I thought only Robinson pilots had to make apologies for the maneuvering characteristics of their aircraft :E

WillyPete 29th Apr 2019 15:16


Originally Posted by aa777888 (Post 10458902)
And I thought only Robinson pilots had to make apologies for the maneuvering characteristics of their aircraft :E

cheeky. At least we have to worry less about whirly bits coming off.
If there’s any helo without “quirks” we’d have to admit to plankers that it’s an easy job flying these.
That will never happen.

Robbiee 5th May 2019 04:01

Seems another Cabri has gone down, if the report is accurate, that is? You have to go pretty far down to find where they mention the type.

https://www.baltimoresun.com/news/ma...504-story.html



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