Are people running their antenna inside the tail boom without reception problems? I have heard of range and receptions problems running an antenna inside of carbon and want to know before I close the fuse up.
Running your reciever antenna inside the carbon boom will reduce your range. You will likely still have enough range to safely fly the model though.
Much of the recent discussions about range problems caused by carbon fuselages is due to the use of carbon/kevlar hybrid cloths used by many of the newer molded airplanes. The carbon/kevlar hybrid cloths are especially bad in terms of RF signal shielding. Some of the recent talk about reciever antenna installations in carbon booms has been started by me as a result of my desire to learn more about the subject. Here is some of what I have learned so far;
Putting the reciever antenna inside a carbon boom substantially reduces your effective range.
Wrapping the antenna around the outside of the boom or just running along the boom on the outside is probably not any better.
To eliminate the range loss from carbon shielding you must get the antenna completely away from the carbon by exiting the fuselage ahead of the tailboom and then running the antenna wire to the tip of a tail feather. This of course is ugly and unapealing.
35MHZ signals are much more adversely affected by carbon shielding than are 72MHZ signals. You will likely still have enough range to safely fly with your antenna inside a carbon boom if you fly on 72MHZ as we do in the States. You will not be able to safely fly that way on 35MHZ.
The reason that you hear so much talk about this topic is that the theory is not well understood and the real world experience that you will encounter will vary wildly and unpredictably form one antenna installation to the next due to a variety of very subtle and not well understood effects. If the theory werte well understood and there was a single simple solution, everyone would just do it and stop talking about it.
People have been running reciever antennas inside carbon booms for a very long time and getting away with it due to the fact that our radio equipment is so good that we have lots of range to spare. Some guys have always shyed away from putting the antenna inside a carbon boom and instead ran the antenna outside or wrapped it around the boom. This likely didn't help their range much if at all but they too still had enough range to spare. The particularly bad shielding properties of the carbon/kevlar hybrid cloth used in some new molded sailplane models has caused the loss of some models and this has started all the talking again.
So, finally, after all that background I can tell you that I have always run my antenna inside the carbon tail boom and likely will continue to do so ( don't do this if you fly on 35MHZ). I believe that the Luchenbach fuselage will offer far less carbon shielding than the original Mantis fuselage since the tailboom of the Luchenbach fuselage has a far thinner carbon skin. I just finally finished my Aegea Mantis with a Luchenbach fuselage and it shows a very good ground range check with the antenna inside the boom. To ground range check a model you should stand the model up vertically so that the tail boom is up off the ground. Perhaps lean the model up against some non metallic object. You will get very little ground range with the model sitting on the ground with the tail boom (antenna inside) close to the ground. Nobody can tell you what range to expect for you particular model but on mine (with a Luchenbach fuselage) I got beyond 100 feet with the transmitter antenna completely colapsed and still had good response. I didn't have a helper to tell me if the servos were jittery or not and that was about as far away as I could go and still see if the servos were responding. Far enough for me. You can do some experimenting with your own model by doing ground range checks with different antenna installations. Include a check with the antenna tied off to a tail tip or some other arrangement that gets the antenna away from all carbon bits just for comparison. Become familiar with what range to expect from your particular radio gear and your particular model and that way you will know if a problem has developed with your radio gear or if a new antenna installation has radically reduced your range.
Sorry for the long response. I could have just said; "run the antenna inside the boom" and most likely nobody (flying on 72MHZ) would have had a problem. This long post should at least give you some insight when you read the next RCSE thread about reciever antenna installations inside carbon booms and you may understand why the opinions are so diverse. You can see this sort of thread also in some groups where some of the guys are European (flying on 35MHZ) and the others are American (flying on 72MHZ) and the people involved in the discussion have no clue that what works for 72MHZ will not work for 35MHZ.
Phil, Thanks, that is the reason I subscribe to this thread. My build got held up while I gathered information on aligning a V-tail but now is moving along well.
Antenna in carbon fuselage?
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Posted - 03/28/2004 : 1:57:09 PM
