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Old Jun 04, 2014, 11:07 AM
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2.4 in Carbon Fuse - Antenna Placement

Sorry for the lame question as I'm very late to the party on this one. I've been using 2.4GHz in my foamies for a while now and am going to make the jump to switching my carbon bird over to 2.4. The plane has about 150K miles on the odometer, so it might make for a good test bed. And it's loaded with carbon from fuse reinforcements, etc.

Is the prevailing wisdom on antenna placement to have them poke out from the sides of the fuse, in front of the wing? How much of the antenna has to be/should be outside the fuse? I can run almost the entire length of both antennae outside, but I read that only the unshielded portion needs to be external - which would make for a neater install.

I know I could have posted this somewhere else, but I trust the advice here the most.

Thanks in advance,
Dominic
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Old Jun 04, 2014, 12:31 PM
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Hi Dom

On my Carbon Espada I mounted a Spectrum 6255 Carbon Receiver (6 ch with long antenna coax leads) such that the leads poke out of the fuse ahead of the canopy. My 2.5 M carbon speed has the hitec 9 channel receiver with the antenna sticking out about mid way on the canopy opening. I put a 9 ch hitec rxer in my MCT and since the fuse is big I placed the receiver behind the wing with the antennas poking out either side about 3 inches behind the TE.

My blade has a spectrum receiver with an external antenna added so there are three antennas sticking out: (Dont be dazzled by the paint scheme)

http://www.rcgroups.com/forums/showthread.php?t=1835872

The slip on nose cone was a challenge and the fuse is too narrow to get the antennas leads out the back straight from the receiver so I poked the antennas out the side of the slip on nose cone and basically dont remove the nose cone unless I need to. I use a piece of piano wire to flip to flip the on off switch through a hole in the side.

On the spectrum receivers I check'ed the reception log after almost every flight on the Espada and occasionally get fades on one antenna (a), 0 on the other, 0 Frame losses and 0 Holds. I seem to get fades recorded due to the on off switch.

The Blade has been perfect 0 everything.

I cant tell on the hitec system but no issues so far knock on wood.

One thing I heard from Dr Marty was to keep the antennas 2 or more wavelengths away from the wing. So two of my planes have he antennas out in front of the wing, one behind and one either side.

Also just the last 31 mm need to be outside of the fuse.

Ray
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Old Jun 04, 2014, 01:25 PM
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Thanks for the very detailed post, Ray. Most helpful.

I remember that carbon Blade! John made me maiden it for him maybe 4 years ago. There was about 1 cm of play on both elevators!! I think Daboz was charged with retrieving the wreckage at Parker a few months later. Glad to see it has lived a useful life afterwards.
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Old Jun 06, 2014, 07:51 AM
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Hey Dom, I think there've been a few threads on this subject. The blocking effect of the carbon seems to be very variable from plane to plane and you have to try it - and thoroughly range test. Get the antennae outside, as far in front of the wing as possible. Locate them so they are roughly perpendicular to each other. You get far better reception if you lift them away from the surface, even slightly - by putting even a bit of thick tape under them, or sliding them inside plastic sheaths and taping over those. One important thing is that if you leave the exposed part free, they will fatigue and crack at the point where they emerge from the sheath - quite common and dangerous. So either protect those bits with heatshrink, or put a dob of Goop around the end of the sheath, or tape them down.

The Stratos has the aerials outside and never an issue. The Wizard BPV is really difficult , probably because there is very little gap at the back of the nose cone so the stalks come out close to the wing LE. It's very fussy and easy to get signal blockage, so much so that I've resorted to pulling the stalks out longer and taping them forwards over the nose cone, each time I put it on!
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Old Jun 06, 2014, 10:02 AM
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Quote:
Originally Posted by screamin' eagle View Post
Thanks for the very detailed post, Ray. Most helpful.

I remember that carbon Blade! John made me maiden it for him maybe 4 years ago. There was about 1 cm of play on both elevators!! I think Daboz was charged with retrieving the wreckage at Parker a few months later. Glad to see it has lived a useful life afterwards.
I remember that... Wasn't John Kim flying the plane? Hell, if I knew it was a healthy young guy like you I would have just pointed it out. Never went further down that canyon.

I recently bought a carbon NYX, put an Atomic NYX's glass canopy on it and placed the whiskers in small tubes under it but keeping them as far from carbon as possible. I range checked it with the belly of the plane between the canopy and the whiskers . Flew it a few times. Yes I was nervous at launch but it seemed to work fine. I think the trick is to get the whiskers as far from the carbon as possible. I assume that the radio waves wrap around the carbon structure and or reflect.
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Old Jun 06, 2014, 05:34 PM
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The point being that the boat or keel, inside the glass nose cone, is still carbon? Is that right Chris?
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Old Jun 09, 2014, 10:14 AM
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Originally Posted by daboz View Post
I remember that... Wasn't John Kim flying the plane? Hell, if I knew it was a healthy young guy like you I would have just pointed it out. Never went further down that canyon.
Yeah I wasn't there the day John stacked it in - I had just heard you were the lucky winner of the free roundtrip retrieval hike
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Old Jun 09, 2014, 11:56 AM
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That Blade has 9 lives. When John gave it away I figure it'll be a good airframe to practice composite repairs and painting. I think the wings are half West Expoy, cabisol and bondo now. It weights 70 oz RTF with no ballast now.

Andrew has a point about the antenna flex. I've used these white antenna guides:

http://www.wiredrc.com.au/shop/image...%20pic%202.jpg

and these black antenna guides:

http://www.rcgroups.com/forums/showp...5&postcount=29

I also made up some foam pads (EPP) that I tape around the fuse to protect the antennas from getting folded over or being crushed when stored or in transport.
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Old Jun 09, 2014, 12:00 PM
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Originally Posted by AvB View Post
The point being that the boat or keel, inside the glass nose cone, is still carbon? Is that right Chris?
Sorry Andrew... Just noticed this

Anyway, the whole fuse tip to tail including the canopy and canopy cover on the standard f3f NYX is carbon.

What I did is replace the canopy cover with one from an Atomic NYX, (made of glass) and put the whiskers under that. So when I ranged checked there was full carbon between the radio and antennas. No direct line of sight without carbon between.

It still works. I've flown it a few times now and it seems fine. Specked it out and flew it directly over head and it still worked.

I wanted to test this well because I'm planning on the doing the same thing with my full carbon K100.

c
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Old Jun 09, 2014, 12:30 PM
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Originally Posted by rockbus View Post
That Blade has 9 lives. When John gave it away I figure it'll be a good airframe to practice composite repairs and painting. I think the wings are half West Expoy, cabisol and bondo now. It weights 70 oz RTF with no ballast now.

Andrew has a point about the antenna flex. I've used these white antenna guides:

http://www.wiredrc.com.au/shop/image...%20pic%202.jpg

and these black antenna guides:

http://www.rcgroups.com/forums/showp...5&postcount=29

I also made up some foam pads (EPP) that I tape around the fuse to protect the antennas from getting folded over or being crushed when stored or in transport.
I agree some guides are needed. Horizon has nice ones as well:

http://www.horizonhobby.com/products...-guide-SPM6824

But I still worry about fatigue on the pressure points.
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Old Jun 16, 2014, 02:05 PM
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I went ahead and mounted the two aerials sticking out of the fuse adjacent to the canopy. Range test was good and the test flight went off without a hitch. Never had a beep to indicate a compromised link (although some of my foamies beep fairly consistently).

I received the antenna guide from Horizon but it's only one guide per pack!! Worse yet, it requires cutting a slot in the fuse (in addition to the hole) where the guide mounts. No thanks.

Gonna try some of the ones in Ray's links above.
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Old May 21, 2015, 02:57 PM
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Anyone using 2.4 in a D80 and running the antennae internally? It seems to be mostly/all Kevlar, just checking.
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Old May 21, 2015, 05:16 PM
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Old May 21, 2015, 06:24 PM
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Old Yesterday, 08:02 PM
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Hey guys. If you have frisky you can buy up to sixty cm long antennae, which I use to put the antennae about midway down the boom, sticking out at 45 degrees just above the midline. To hold the whiskers I use a few layers of heatshrink over each other, tapering to about three layers at the fuse. This supports the whisker really well. I either hot glue or CA them into the fuse. I've never had an issue with reception this way and the whisker is relatively protected from breaking off. I don't really like antenna tubes for 2.4 as I have had a couple of aerials slip back inside the fuse without me knowing. The heatshrink seems to hold onto the whisker a bit better.
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