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antennas in a foil covered airframe

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Old 03-18-2010, 04:05 PM
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ram3500-RCU
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Default antennas in a foil covered airframe

Thanks in advance to any who can help. I have built a Meister P-47 and covered it with aluminum foil. My question is, are their any issues with internal antennas in a plane like this. I am initially installing 72mhz, but will be changing to 2.4 soon. I planned extensive range testing, but thought maybe someone would have dealt with this already.
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Old 03-18-2010, 04:40 PM
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Default RE: antennas in a foil covered airframe

I would think that if you run the antenna outside the aircraft and ran a good Range Check you would have a better idea of whether or not the signal will be affected. I am not sure if the Foil will generate any RF Noise that might interfere with the Rx.

In the early 80's, I mounted a Super 8 camera under my plane and was taking movies while flying. The Rx went crazy from the electric motor on the camera, so I wrapped the camera in Foil, except for the Lens, and I got away from the problem.

Since 2.4 antennas are inside the aircraft, I would be concerned that the Foil might affect the signal. I know that Carbon Fiber fuselage's block 2.4 signals.
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Old 03-18-2010, 10:50 PM
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Default RE: antennas in a foil covered airframe

Putting aluminum foil on an airplane is a bad idea from the RF standpoint.
You will be better off on 72 if you run the antenna outside the airplane. Even so you might get blockage or dead spots.
If you are going to 2.4 get a system that has at least two satellite receivers that you can mount at different places on the airplane so you won't be shielded from your transmitter
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Old 03-18-2010, 11:44 PM
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Default RE: antennas in a foil covered airframe


ORIGINAL: dirtybird

Putting aluminum foil on an airplane is a bad idea from the RF standpoint.
You will be better off on 72 if you run the antenna outside the airplane. Even so you might get blockage or dead spots.
If you are going to 2.4 get a system that has at least two satellite receivers that you can mount at different places on the airplane so you won't be shielded from your transmitter
Can you explain why it is bad? I'd like to know more. Many planes are done this way.
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Old 03-19-2010, 10:45 AM
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Default RE: antennas in a foil covered airframe

Any time you have an antenna inside an electrically conductive container you will block the receiver from receiving any signal, it is the same as putting it in a Faraday cage. What Dirtybird said except he should have also said that, even on 2.4GHz, the active ends of those antenna must be OUTSIDE the fuselage if the fuselage is covered with an electrically conductive material.
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Old 03-20-2010, 11:30 PM
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Default RE: antennas in a foil covered airframe

The Faraday cage:

http://en.wikipedia.org/wiki/Faraday_cage
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Old 03-21-2010, 10:49 PM
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Default RE: antennas in a foil covered airframe


ORIGINAL: dirtybird

The Faraday cage:

http://en.wikipedia.org/wiki/Faraday_cage
Yes. Good point. I'm not going to take a chance on 72mhz. In years past I would have had to find a way to get the RX close enough to the top to still have plenty on antenna outside. With 2.4, I've been told I need not worry. I'll be converting prior to flying her.
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Old 03-22-2010, 08:00 AM
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Default RE: antennas in a foil covered airframe

If you're able to get a satellite receiver in the canopy you'll be in good shape. Of course range checks are in order. Mitch
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Old 03-22-2010, 08:05 AM
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Default RE: antennas in a foil covered airframe

Check with BVM (Bob Violet Models). They have many beautiful expensive Jet kits and Jet ARFs with beautiful chrome finishes. I am sure they can tell you what kind of coverings and finishes will and won't affect various types of radios and how to avoid problems with interference.
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Old 03-22-2010, 08:07 AM
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Default RE: antennas in a foil covered airframe

You could also try the Jet RCU forums and Warbird RCU forums as they would use chrome type materials more than others.
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Old 03-22-2010, 10:14 AM
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Default RE: antennas in a foil covered airframe

Thanks. From what I have been able to find out, 2.4 is no problem. 72mhz is a no go, unless the antenna is external.
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Old 03-22-2010, 11:04 AM
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Default RE: antennas in a foil covered airframe

I don't know where you get the idea 2.4 will be no problem. That tiny antenna can easily be shielded from RF. Putting it in the canopy is a good idea but even then it will be shielded from you if the airplane is straight overhead. Some 2.4 receivers have extenders that you can run out of the fuselage but then tour airplane will look like it has cat whiskers and you might have multipath problems.
With 72's long antenna you can run it out of the shielded area.
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Old 03-22-2010, 11:36 AM
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Default RE: antennas in a foil covered airframe

ORIGINAL: dirtybird

I don't know where you get the idea 2.4 will be no problem. That tiny antenna can easily be shielded from RF. Putting it in the canopy is a good idea but even then it will be shielded from you if the airplane is straight overhead. Some 2.4 receivers have extenders that you can run out of the fuselage but then tour airplane will look like it has cat whiskers and you might have multipath problems.
With 72's long antenna you can run it out of the shielded area.
I have talked to other experienced modelers who have used aluminum foil and 2.4. They have had no issues with it. With no personal experience yet, it is all I have to go on. Postulation and theory is fine to a point, but actual flight experience with the same material and systems is hard to ignore.
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Old 03-22-2010, 11:41 AM
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Default RE: antennas in a foil covered airframe


ORIGINAL: dirtybird

I don't know where you get the idea 2.4 will be no problem. That tiny antenna can easily be shielded from RF. Putting it in the canopy is a good idea but even then it will be shielded from you if the airplane is straight overhead. Some 2.4 receivers have extenders that you can run out of the fuselage but then tour airplane will look like it has cat whiskers and you might have multipath problems.
With 72's long antenna you can run it out of the shielded area.
We are talking about a very large airplane here. It isn't that easy to get the RX in a location to expose enough of the antenna. And if you do, it just lengthens all the leads to it, creating more issues. I will continue to explore this and seek out practical experience. I appreciate all the posts and advice.
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Old 03-22-2010, 01:36 PM
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Default RE: antennas in a foil covered airframe

Have you heard of the fellow that liked to play Russian Roulette and said I haven't had a problem yet? Practical experience can be misleading,too.
How many have you talked to? 100 will still be a low sample.
Theory does not say you wont have trouble. It just predicts where you are most likely to not have trouble.
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Old 03-22-2010, 02:54 PM
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Default RE: antennas in a foil covered airframe

From what I have been recently been told by experienced scale model builders who use Foil like coverings, use the Spektrum Rx's designed for Carbon Fiber Fuse and be sure that the Antenna exits outside the aircraft.Do the same with any of the 2.4 Rx's if you can.
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Old 03-22-2010, 03:03 PM
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Default RE: antennas in a foil covered airframe

If you have been told by experienced scale model builders who use Foil like coverings why are you asking here? Don't you trust them?
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Old 03-22-2010, 03:08 PM
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Default RE: antennas in a foil covered airframe


ORIGINAL: BuschBarber

From what I have been recently been told by experienced scale model builders who use Foil like coverings, use the Spektrum Rx's designed for Carbon Fiber Fuse and be sure that the Antenna exits outside the aircraft.Do the same with any of the 2.4 Rx's if you can.
OK, I guess there are many opinions on this. Do you guys think a fair test would be to build small boxes covered with foil for the RXs, install them in one of my electric jets or something, and fly it?
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Old 03-22-2010, 03:12 PM
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Default RE: antennas in a foil covered airframe

I am not asking anything. I was just commenting on info that I picked up from some of my fellow club members. They were more familiar with Foil than I and I was just trying to help the OP.

It is the OP who was asking the questions.
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Old 03-22-2010, 03:23 PM
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Default RE: antennas in a foil covered airframe


ORIGINAL: dirtybird

If you have been told by experienced scale model builders who use Foil like coverings why are you asking here? Don't you trust them?
Well, I started this thread prior to actually talking with anyone with experience in this field. I have since been able to talk to some and have posted my findings here as follow up. However, I still am getting conflicting posts that I am reluctant to just ignore.

It isn't a matter of trust. It is a matter of looking at every bit of data I can find on the subject, and making an educated decision on that basis.

So far, no has posted and said, I tried this or that and it definitely does not work. I'm still doing research and trying to get a good answer for all of us.

I'm going to the jet guys for some input as well. I know they like the metal finishes.

Thanks again for all the posts and help.
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Old 03-22-2010, 04:14 PM
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Default RE: antennas in a foil covered airframe

OK. I called BVM. Thought they would have some solid data and experience. Although Bob uses his metal paint system, the technician I spoke with actually has a jet covered in foil. He uses JR / Spektrum. He situated one of the antenna so it was in the canopy(very precautionary on his part he said) and buried all the rest. No issues whatsoever. He also said that after flights, the exposed antenna didn't seem to be any more active than any of the others when checked. He said that none of the reps put antennas in the canopies, and still, no issues. They do have multiple satellites. His recommendation was to do a maximum distance range check, while turning the plane 360 deg.

He was nice to talk with and seemed genuinely interested in my questions.

This helped me. Hope it helps others as well.
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Old 03-22-2010, 07:00 PM
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Default RE: antennas in a foil covered airframe

I guess its time for me to drop out of this thread.
I hope you don't do all of that work of covering your airplane with foil and bury a 2.4 system in it.
Good luck.
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Old 03-22-2010, 07:23 PM
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Default RE: antennas in a foil covered airframe


ORIGINAL: dirtybird

I guess its time for me to drop out of this thread.
I hope you don't do all of that work of covering your airplane with foil and bury a 2.4 system in it.
Good luck.
I appreciate your concern and posts. Not having experience with this situation before, even after over 40 years in the hobby, I looked for advice from those who do. There just are not that many places to go, as a small percentage of our planes are covered this way. All I can relate is what I have learned from those who have or do fly metal covered aircraft. Be assured we will be very cautious with this very expensive new plane, and do all we can to insure it's safety and safety of those who watch.
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Old 03-22-2010, 10:59 PM
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Default RE: antennas in a foil covered airframe

I've worked in electronics for more than 50 years, taught vacuum tube theory before transistors were around. I've taught antenna theory, too. You may be able to get a signal through the foil at close range but be assured that when your "very expensive new plane" is a couple hundred feet out, you'll lose the signal. Especially if your antennas are not located outside the foil. And, as someone else mentioned, even if the antennas are external, if the airplane gets into an orientation where the foil is between the antenna and your transmitter the signal will be blocked. I'd recommend that you do some VERY extensive testing on the ground before flight tests.
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Old 03-23-2010, 07:49 AM
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Default RE: antennas in a foil covered airframe

Put your cell phone inside the plane and call it......same thing, sorta.
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