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CAD - Engineering - Technical > Carbon Canopy ....risks ? ? ?
 
 
dpcarey
Senior Heliman
Location: Ontario, Canada

I am posting this question in an attempt to get some opinions from some of the more experienced flyers.

I have recently made several heli canopies containing varying degrees of 6.8oz carbon fiber cloth (mostly for asthetics). 6.8oz carbon is fairly substantial stuff and closely resembles the carbon weave used in a set of 600mm V-blades. The amount of carbon used in my layups varies from just enough to cover the average windscreen/cockpit area; all the way up to about 2/3 of the entire canopy itself. The look and results of using so much carbon are, needless to say, very attractive. However, I have no first-hand knowledge regarding to the effects of so much carbon on a 2.4GHz or 72MHz radio system. My current impression is that with a 2.4GHz system there should be little concern, but on 72MHz there could be big problems.

At this point I am looking for the real facts of the matter. Hopefully, several can chime in on this.

Thanks,

Dave
02-15-2008 07:11 PM
 
 
mdu6
Veteran
Location: Montreal

Some scale helis feature a carbon fuselage like the big Vario Airwolf so there should be no problem with your canopy.


http://www.variocanada.com/product_...products_id=742
02-16-2008 01:08 AM
 
 
Maxime
Senior Heliman
Location: Belgium

have a picture of it? would like to see the result
02-16-2008 11:47 AM
 
 
dpcarey
Senior Heliman
Location: Ontario, Canada

mdu6 - that Vario is not really a carbon fuselage. It is a CFRP construction = carbon fibre re-inforced plastic. Basically, it is pretty much plastic.

Maxime - I have not bothered to take photos yet, but perhaps I should. Right now, they are primed and nearly ready for paint. But, even primed, they are impressive. I will see if I can get some photos up by Monday.

Cheers

Dave
02-16-2008 03:01 PM
 
 
z11355
rrMaster
Location: 10000 is enough time wasted.

carbon fibre will act as a 'faraday cage' and block radio signals.
02-16-2008 03:12 PM
HOMEPAGE  
 
 
mdu6
Veteran
Location: Montreal

That why you have the antenna outside ...

Sorry for the 'plastic' Vario, but i do remember other full carbon fuse like the Sitar Gazelle, and there are also plenty of planks carbon fuses also.
02-16-2008 04:02 PM
 
 
dpcarey
Senior Heliman
Location: Ontario, Canada

"antenna outside".

Yes, but what about shadowing - positional blockage of a radio signal?

How about 2.4GHz specific concerns? The antennas are so short that shadowing would be easy if, in fact, the carbon affects a 2.4GHz signal...these are my questions and concerns.

My hope, is to hear from some more people with hard knowledge in this area. I am trying to avoid the speculation.


Thanks,

Dave
02-16-2008 04:14 PM
 
 
mdu6
Veteran
Location: Montreal

Why did you build it then !


If it's only a canopy, the 72mhz antenna running outside should not have a problem with 'blockage' (I now, it's speculation !), but we already have quite a bit of carbon going on after all.

Tail blade, horizontal & vertical fins, boom, boom braces, main blades, paddle, skids, frames and some canopies have a carbon screen.

I agree that using a 2.4ghz system with an antenna inside a full carbon canopy would need a good test.

But you should be able to do this easily. I would put a 2.4 receiver, battery, servo inside a canopy and temporary close up the openings with dry carbon cloth and do test.
02-16-2008 04:35 PM
 
 
dpcarey
Senior Heliman
Location: Ontario, Canada

Quote 
Why did you build it then !

If you saw one, I doubt you would ask

Quote 
I agree that using a 2.4ghz system with an antenna inside a full carbon canopy would need a good test.

Like most guys, I`d rather not "test" a couple grand worth of heli, canopy and paint job if I don`t have to - although the suggestion of a ground test is certainly a good (but potentially limited) option. That is why I am posting my questions here and seeking answers from those more knowledgable than myself.

The various effects of Carbon are fairly well-known, and I am certainly not the first guy to make a carbon canopy for a heli. So, I am confident someone will be able to answer my questions with some hard facts and science. Especially with regard to a 2.4GHz radio system.

Booms, frames, tailfins etc may be a whole different ball-park compared to a solid (or near-solid) carbon fiber canopy which could literally put an electro-conductive wall around my radio gear. I am not so concerned about the canopies I`ve made with a carbon windscreen only. My biggest concern is my favorite design where the top 2/3rds of a 600E canopy is solid, 6.8oz carbon laminate.

As I said, it is my understanding that 2.4GHz may be immune to all of the aforementioned concerns. However, for all I know, my understanding may be the equvalent of urban heli myth. An assumption like that could certainly ruin a fellas` day.
02-16-2008 06:14 PM
 
 
mdu6
Veteran
Location: Montreal

You should post this in the Radio or Radio-Spektrum section, you have more chance of catching someone like JKOS there to give a technical answer.
02-17-2008 01:00 AM
 
 
dpcarey
Senior Heliman
Location: Ontario, Canada

good idea. I will do that.
02-19-2008 03:06 PM
 
 
busted blade
Senior Heliman
Location: orlando,florida

http://runryder.com/helicopter/t377318p1/
no radio problems to date with the 72mhz and the antenna out the back

"CFRP" is one of the technical terms for a carbon fiber part. plastic is the resin matrix which is reinforced with the carbon fiber

bling bling, cha ching......... but honey
02-21-2008 04:36 AM
 
 
dpcarey
Senior Heliman
Location: Ontario, Canada

busted blade...thanks for the input, it is appreciated.

I am not entirely in agreement with your definition of "CFRP". Some manufacturers are now putting miniscule strands of carbon in an otherwise plastic part (not a resin laminate part) and calling it CFRP. This is very misleading as it allows them to call a blade - for example - "Carbon" even though it is not a carbon composite laminate. As you know, the difference in performance, appearance and construction costs are huge.


Dave
02-21-2008 03:26 PM
 
 
busted blade
Senior Heliman
Location: orlando,florida

i dont doubt that people are using the term incorrectly but that is what it was called in the begining long before most even knew what the stuff was. but im not here to argue the point. good luck with your canopy. im working on the molds for a carbon canopy for my 450 using compression molding. ill post the solid model, mold, and results when im done.

bling bling, cha ching......... but honey
02-21-2008 09:08 PM
 
 
HeliPhil
Senior Heliman
Location: UK

try searching other general RC forums under gliding - they have lots of problems / ideas with 2.4 and 72 radios - until recently most glider fuz were carbon....

http://www.olsonracing.co.uk
02-28-2008 11:55 AM
HOMEPAGE  
 
 
Edwardn
Heliman
Location: northridge, CA

Hi guys.
I am working as design engineer for company which makes antannas for different aplications (will not list them for .... reason).
CF is not RF transparent and if antenna located inside canopy-it will be for sure bloked (2.4 Ghz), but if antenna located outside-it will be fine specialy on 72 MHz, even if in some position of bird it can be bloked from direct site of transmitter-it still will work good. I just worked on project where antenna was located on surface made of CF and we had no problem with performance.
If somebody wants to try-try it on your own risk, don't use my words as a laws, i just tell what I am designing and what have expirienced.
03-02-2008 07:32 AM
 
 
busted blade
Senior Heliman
Location: orlando,florida

Edwardn,
thats good to here from your exprience. i can confirm i have flown with my CF canopy directly between the TX and RX antennas (like nose in) with 72mhz. so does this suggest that the waves can flow around the rf obstruction? please share any insite you might have in regard to this phenomenom or how radio waves act in general as i as well as others would like to have a better technical understanding.

bling bling, cha ching......... but honey
03-02-2008 06:17 PM
 
 
Edwardn
Heliman
Location: northridge, CA

RF wave can't go around RF non-transparent materials, but hit surface and bouncing out, creating new point of wave which going on circle pathern. So if surface doesn't have infinity lenght, eventualy wave will go behind surface. Every time wave hit RF non trnasparent surface it also dimming out, so the onger surface-greater possability RF wave will dimming out to 0. There are many things involved in RF-one of them if friquency-higher number make RF get weaker way faster. BTW, this the reason I am personaly will not use 2.4 GHZ for this aplication. I don't want to start here "war" if 2.4 GHz is good or not, but personaly I will stay as low as possible-72 Mhz, may be even 50Mhz.
03-02-2008 07:25 PM
 
 
MattJen
Key Veteran
Location: UK,Gravesend, Kent

On thr Vario Large Carbon Airwolf which i did have, the manual insisted and provided arial clamps for running it outside the fuse..
it made the point that if 1 3rd of the aereal was inside the carbon fuse then 2 thirds must be outside or RF intereference would occurr.

Even on my larger turbines i always run it out of the rear of the carbon canopy, and this is on the 35meg band...

I have never had a lock out...

Matt

Ps- really interesting thread, thanks for the info i have learnt a lot, it is nice to find the WHY you have to do something rather than just follow the instructions.



I bought my Mother-in-law a chair for xmas, but she wouldn't plug it in
03-04-2008 01:09 AM
 
 
dpcarey
Senior Heliman
Location: Ontario, Canada

EdwardN,

Very valuble info. Thanks a lot.

Dave
03-04-2008 03:24 PM
 
 
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CAD - Engineering - Technical > Carbon Canopy ....risks ? ? ?
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