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Old 7th Sep 2005, 09:19   #21 (permalink)
 
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You certainly have to hand it to the French that they are tops at helicopter design. They have seen the adverse comments of the R22 and produced what looks like the next light helicopter to be found in the training schools and everyones back garden.
The fenestrn blades are all equally spaced which is unusual now that unequal spacing is found to be quieter.
Looks good and spec looks just right. Lets see the flight performance data now.
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Old 7th Sep 2005, 10:44   #22 (permalink)
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Fenestron

As I mentionned in other related tracks, I attended some VH-diagram testing by the DGAC, in Aix in July.

I do remember, but you have to check perhaps the pictures, that the fenetron is assymetric as it should be.

This maybe difficult to see/confirm because it has 7-blades


d3

Last edited by delta3; 7th Sep 2005 at 10:55.
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Old 2nd May 2006, 14:47   #23 (permalink)
 
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From Volare, the Italian aviation magazine who did a story on the Cabri recently.

The Italians claim the donk they saw in their machine was a 360 with a fully automatic electical start.
Empty weight of 420, MTOW 700 kg
VNE 120, cruise at 100.
170 litre tank
got to 10000 ft in just over 7 minutes ( picture shows a very stripped down version when they did this) and reached 21840 ft, breaking the piston engine helicopter altitude record.
Belt drive Eng to MGB
Shock proof tank (I remember when I did the AS350 course in the mid eighties and the frogs said it has a "crashproof tank")

Anyway it's all just from the magazine artical, the Italians from Agusta said I would have no problems getting spares for my 109 as well...
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Old 12th Oct 2007, 23:37   #24 (permalink)
 
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Guimbal Cabri G2

http://helimat.free.fr/2005/aout/Rou...YHG/index.html

So anyone know the latest on this model? Is it being offered yetr? Price? Good, bad, ugly?

Thanks,
Monk
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Old 13th Oct 2007, 09:12   #25 (permalink)
 
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Cabri

Price 260,000 Euros plus tax. Don't think it has been certified yet, you can order via email of their website. http://www.guimbal.com/
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Old 13th Oct 2007, 12:41   #26 (permalink)
 
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Thanks for the link MM2, but it didn't work for me. This is what I get.

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Monk
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Old 13th Oct 2007, 14:01   #27 (permalink)
 
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Cabri

I tested the link just now and it works fine for me. Here is the email address
helico.guimbal@free.fr
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Old 13th Oct 2007, 15:11   #28 (permalink)
 
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Interesting rotor head, with lots of nice expensive castings. I couldn't quite see how the bearing worked inside that Y root. Is it a plain spherical bearing/bush (fully articulated) or is there no flapping movement (hingeless)?

The pitch horn angle suggests hingeless, but with three rotors i would guess it is articulated to avoid 3P vibration. If so, why not stick to cheaper teetering head.

Notice the strain gages on the red blade set. I guess the machine is still going through fatigue life determination testing. The more i learn about fatigue life prediction using residual strain energy, the more scared i become stressing parts. Maybe that fancy LCD instrument display will have HUMS installed too.

Last edited by Graviman; 13th Oct 2007 at 15:29.
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Old 13th Oct 2007, 17:11   #29 (permalink)
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According to a review in the French magazine "Aviation International" the head is semi-rigid, and very similar to that of the EC120. Bruno Guimbal, the designer, was the deputy head of the EC120 development project at Eurocopter.
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Old 13th Oct 2007, 17:49   #30 (permalink)
 
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Mart,
EC 120 ~ Rotor Head
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Old 13th Oct 2007, 18:23   #31 (permalink)
 
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I had same page as Monk
Price seems within ball park for new helio with latest gismos But what engine?
Please not a Lycasorus
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Old 13th Oct 2007, 18:37   #32 (permalink)
 
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Ah, thanks guys! I guess they tune the stiffness to keep blade 3/4 wavelength mode below 3P then, while keeping good cyclic control for reduced g manouvres. Nice reliable design, although i wonder about the control forces.

I've dealt with Lord, Trelleborg and Silentblock for spherelastic bearings, and have always been impressed at what they were capable of withstanding. The only problem i've ever come across is that they are difficult to life, especially if you cannot define the exact duty cycle. Failure is easy to spot though from rubber splitting, and the failure mode is nice and progressive.

Dave did you ever get anywhere with your compliant hub design? I always thought this was one of your best ideas.

That fenestron looks interesting in a small helicopter too. How does it handle foward flight, without teetering and delta3? Does the advancing side end up producing most of the thrust, or is that a cyclic servo i see?

Last edited by Graviman; 13th Oct 2007 at 18:52.
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Old 13th Oct 2007, 21:00   #33 (permalink)
 
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Quote:
>>>"The more i learn about fatigue life prediction using residual strain energy, the more scared i become stressing parts."

I thought everyone used Miner's Cumulative Damage. Do the cert agencies allow life determination with a residual strain energy method?


The strain gage there is quite standard in flight test programs. Most control system loads can be correlated to PR load.
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Old 13th Oct 2007, 21:10   #34 (permalink)
 
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Smile

Mart,
Quote:
compliant hub design
Heck, I've looked at just about every other type of hub design there is, in an attempt to win the 'Nick Lappos Free Lunch Award'.
At the present time a small snack on a paper plate would look good.

Dave
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Old 13th Oct 2007, 22:15   #35 (permalink)
 
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Hoss, I have no doubt the team that designed the Cabri know what they are doing.

Miners law allows you to combine a number of different loadcases to determine the overall fatigue damage, or to determine the life of a component. The problem is working out where each loadcase is on the Stress-Number_of_cycles curve. For stress calcs the traditional method is using the Goodman's diagram, or variations of it, to combine average and cyclic stress into an equivalent cyclic only stress to check against S-N curve. The problem is that this method is not accurate in life prediction, as there is huge scatter in coupon S-N testing.

A more recent development comes from the understanding that even below the elastic limit there is some residual strain after each load application. Basically the material is not perfectly elastic, but always recovers alongs Young's modulus. Consider the 0.2% plastic strain proof stress generally regarded as material yield, if you reach this then unload the component you will have a residual 2000 microstrain. Lets say taking the component to half Ultimate Tensile Strength, then unloading it leaves a residual strain of 1 microstrain. This means you can do this 2000 times before the component reaches a strain where it yields on the next application.

If any of the design engineers that occationally appear from the aether vaccum can offer good practical guidance here, i'm interested BTW. It seems to me that the only chance of producing reliable numbers is to use the fatigue software built into many FE codes. It's a specialised area.

If anyone else is interested in fatigue, here is some general info:
http://en.wikipedia.org/wiki/Fatigue_%28material%29

Last edited by Graviman; 14th Oct 2007 at 08:03. Reason: Trying to make this more readable - i am no expert on this.
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Old 10th Nov 2007, 16:31   #36 (permalink)
 
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Quote:
According to a review in the French magazine "Aviation International"
http://www.aviation-international.ae...rticle=1&aff=1

Direct link to the two reviews at bottom of this page:
http://fr.wikipedia.org/wiki/Cabri_G2

It's in french, with nice pictures.
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Old 11th Nov 2007, 17:18   #37 (permalink)
 
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cabri g2

According to the developer this Helicopter will have a full EASA cs-27 certification signed this month. More information on their web site will follow along with magazine flight reviews.
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Old 31st Dec 2007, 20:26   #38 (permalink)
 
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Looks like it made the grade...

http://www.amtonline.com/article/art...tion=1&id=4879

If it now has EASA certification I wonder how long before it shows up here in the states.

Max
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Old 31st Dec 2007, 22:31   #39 (permalink)
 
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It seems to have a pretty substantial amount of engineering(almost over engineered) in the Rotorhead, and has nuts and bolts that seem a first glance to far bigger in size that the R22 that this new heli seems to be aimed at, plus the price seems to be in the right ball park also!

About time some one had the ability to compete with Franky the Yankee, it may push him into more spectacular things now!

Peter R-B
Vfrpilotpb

Happy new to one and all!!

ES: it says in the Lit that it has the Lycoming 0-360!!
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Old 1st Jan 2008, 07:36   #40 (permalink)
 
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Cabri

A friend of mine here in France who has ordered one of the 12 that have had deposits paid for reckons that it autos on a par with a Bel 47.

The chap that owns my airfield is a supplier of plastic moulds for it.

Price is more expensive than an R22 so it will be difficult to break into the market.

It does have a dedicated baggage locker in the fuselage.

Have you seen the demo video from Rennes ? Quite impressive and up to D Kenyon H300C level.

http://216.122.254.24/Cabri%20Helicopter.htm

Stills here:

http://www.jiepie.com/files/guimbal/...es/index2.html
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