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aeajr
477 Posts |
 Posted - 04/13/2007 : 09:56:21 AM
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With the move toward 2.4 GHz radio systems the materials used in the fuselage might have to be reconsidered.
There has always been a concern about carbon in the body, even with 72 MHz systems, but it seems 2.4 GHz is even more sensative to carbon and is more easily blocked. So, how important is it to use carbon in these high strength designs. Can Kevlar handle it? Or can carbon be used only in key areas to leave a more radio friendly fuselage material?
This could be even more critical in the DLGs where space is tight so things like dual receivers might not work at all. Can we use more kevlar and less carbon? Perhaps the bottom of the fuse can be left more radio friendly.
Just wondering as somewhere down the road people may start to turn away from carbon because it blocks the radio waves used to control the planes.
I don't know much about this stuff, but I was curious about what the wizards think.
Best regards,
Ed Anderson
ESL Content Editor
aeajr on the forums |
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Anker
83 Posts |
Posted - 04/13/2007 : 10:16:29 AM
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You have to realize that carbon fiber and kevlar have very different properties. This is why you have never seen a boom made of kevlar. Carbon fiber embedded in epoxy has great compression and tension strength. Kevlar has fantastic tension strangth and is very poor in compression. There's a reason why spars are made of carbon and are wrapped in kevlar!
Anker |
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aeajr
477 Posts |
Posted - 04/13/2007 : 3:07:50 PM
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A carbon boom would be no problem as the 2.4 GHz recivers have tiny antenna that is completely housed in the fuse or pod, so that is the part of the plane of concern. An RF window in the fuse is needed to let the receiver see out and let the waves in.
What did we use before carbon? Fiberglass I guess. For the pod, or fuselage, would it be hard to go back to glass or glass/kevlar?
Best regards,
Ed Anderson
ESL Content Editor
aeajr on the forums |
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kiesling
45 Posts |
Posted - 04/16/2007 : 2:34:26 PM
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Glass works fine for a fuse pod. There is a slight weight advantage to using carbon. I think most people use carbon for the fuse pods for the look. I expect to see a lot more glass in fuses as spread spectrum becomes the norm. . .
The thing I'm not sure about is how much carbon can we keep in the wing? Will there be blocking issues at certain orientations?
Tom |
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aeajr
477 Posts |
Posted - 04/16/2007 : 3:14:20 PM
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Good question Tom.
I have not heard of much concern about the wing as a blocking issue, unless the receiver is right underneath or in the wing. In thermal sailplane flying, where you are normally looking up from below, if the fuse/pod were transparent, any blocking from the wing would be monentary and not likely to cause a problem in a sailplane. The receiver would go to "hold last" unless set to some other setting. That would probably fly you through the 1/2 second gap and pick right back up. I imangine you might not even notice it if you were blocked.
You could have a slope plane making a high speed pylon turn where the wing might blank the receiver for an instant. I suppose that could happen.
Time will tell but I bet carbon wings will not be a big issue, especially with the Spektrum AR7000 where you have two receivers that are 2 inches apart.
However a pattern plane might potentially have a problem at close range doing a knife edge or a deeply banked turn with the wing toward the pilot and the receiver under the wing. Then I imagine some blanking could occur, but how bad and for how long, I have no idea. I wonder if it would be less of an issue because the TX was so close. One does not usually do knife edges at 1/4 mile out.
Best regards,
Ed Anderson
ESL Content Editor
aeajr on the forums |
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aeajr
477 Posts |
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aeajr
477 Posts |
Posted - 08/27/2007 : 06:29:54 AM
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I have read in two places now that Barry Kennedy of Kennedy Composites is bringing out 2.4 GHz friendly versions of his most popular planes.
Best regards,
Ed Anderson
ESL Content Editor
aeajr on the forums |
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Fuselage Design to be 2.4 GHz Friendly
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