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airmcn_3
Mar 24, 2009, 09:36 PM
I have a carbon fiber flying wing; I have since been forced to go to 36 MHz instead of 2.4 GHz for RC transmission. I did the maiden flight this morning and had some serious frequency hits; I believed this was due to the fact that I was using a single conversion Hi-Tec micro Rx. I have since changed it out with the 319dp dual conversion full size rx hoping it will get rid of the frequency hits. The antenna is running out the fuse of and down the bottom side of the wing.

So now for the question. How are the guys with carbon fiber flying wings working around the frequency issue?

Thanks,

Chris
smh20502
Mar 25, 2009, 01:56 AM
why can't you use 2.4g? if it's frequency blocking of the CF simply locate the rx on the skin, punch holes for the antenna, silicone around the holes.
airmcn_3
Mar 25, 2009, 02:35 AM
why can't you use 2.4g? if it's frequency blocking of the CF simply locate the rx on the skin, punch holes for the antenna, silicone around the holes.

I can’t use 2.4 any longer because I am transmitting 1W 2.4 video. So are you saying that with the antenna ran outside the aircraft the CF will not interfere? I have been told otherwise but would love to hear differently....

Chris
rbeall
Mar 25, 2009, 03:46 AM
Carbon plays tricks on RF if your not careful. I would get the antenna out of the airplane as soon as physically possible and keep it in a straight line as much as possible with no 90deg bends. I would also put it on the bottom of a flying wing beings the top would also shadow RF from the user's perspective.

Any more, anything not on 2.4 gets hit pretty bad unless you live out in the middle of nowhere. I flew a trex450 and couldn't fly anywhere without getting hit. Switched to 2.4 and no problems. If you continue to have problems fly the same RX on a balsa plane and see if its just some local interferance unless you have a Spektrum analyzer?
ShadesOfGray
Mar 25, 2009, 11:32 AM
As mentioned by others, external antennas are the way to go if you're using carbon fiber. We've had no trouble with that arrangement so far....

http://www.vanderbilt.edu/USLI
smh20502
Mar 25, 2009, 12:40 PM
switch your video to 5 gig? I've used 2.4 gig video with no issues with my spektrum dx7. There were interference issues with the video but that was it.
airmcn_3
Mar 25, 2009, 06:25 PM
Thanks guys,

Well the aircraft had a crash this morning, I did an extreme range test on the ground with antenna in, there were no issues during this test. I took the TX about 150m away with antenna in and no signs of frequency problems. I should be able to fix it but I refuse to fly on 36 MHz again with this current configuration.

I have every frequency video system sitting here, I have tested every one of them with extreme range tests, so far the 900 MHz system has been the most bullet proof but unfortunately that is the frequency our modem is on. I have used 5.8GHz with good results but 3km seems to be the max I can get out of that particular system. We need a solid 5km of video and telemetry.

Anyhow I appreciate the comments; hopefully I will come up with a solution.

Chris
CenTexFlyer
Mar 25, 2009, 09:35 PM
Chris,

We fly our wings with a carbon/kevlar hybrid fabric and have had no problems with our 72mhz radios with 2.4Ghz video systems. Additionally, we use a 900Mhz radio for our telemetry/comms on our autonomous bird.

Gene
airmcn_3
Mar 25, 2009, 10:14 PM
Chris,

We fly our wings with a carbon/kevlar hybrid fabric and have had no problems with our 72mhz radios with 2.4Ghz video systems. Additionally, we use a 900Mhz radio for our telemetry/comms on our autonomous bird.

Gene


Gene, I was hoping to hear from you as your aircraft are almost identical to ours in materials and component transmission.

Do you have the antenna taped to the bottom of the wing?

I just switched out my RC RX back to 2.4 GHz and changed my video to 5.8 GHz for now, I am getting ready to go test again. Hopefully all is well. I will keep everyone updated. BTW my RX antennas are outboard of the aircraft....

Thanks,

Chris
Gary Evans
Mar 26, 2009, 02:11 AM
Are you aware of Thomas Scherrer's long range RC system?

http://tinyurl.com/6qnt5p
RolandS888
Mar 26, 2009, 08:44 AM
Thanks guys,

I have every frequency video system sitting here,.......

.......... so far the 900 MHz system has been the most bullet proof but unfortunately that is the frequency our modem is on.

Anyhow I appreciate the comments; hopefully I will come up with a solution.

Chris

Just out of interest Chris, what data modem are you running that is happy to be inside CF?
CHeers,
R.
airmcn_3
Mar 26, 2009, 06:41 PM
Just out of interest Chris, what data modem are you running that is happy to be inside CF?
CHeers,
R.


I am using the 9Xtreem modem from DIGI, the modem is inside the carbon but well insulated from it, the antenna is sticking right out the top of the wing.



Chris
airmcn_3
Mar 26, 2009, 06:43 PM
Are you aware of Thomas Scherrer's long range RC system?

http://tinyurl.com/6qnt5p


I am, but I have been told that 488MHz is not legal over here.... I will contact him and see if he has a solution to this.

Chris
Gary Evans
Mar 27, 2009, 10:00 AM
Another possibility would be DMD. They make a long range system that operates in the 869-915Mhz band.

http://tinyurl.com/ckgojj
airmcn_3
Mar 27, 2009, 05:59 PM
Another possibility would be DMD. They make a long range system that operates in the 869-915Mhz band.

http://tinyurl.com/ckgojj


Gary,

We have talked about increasing the baud rate on the Xtend modem and running rc control through that, its just talk right now but hopefully we will come up with something.

I did two auto flights yesterday; the aircraft is flying very well. I did have to change back to 2.4 RC and 5.8 video to get rid of any interference, not sure what that says for 36 MHz as everyone tells me the 2.4 should be having more problems with all the carbon.

I will keep this tread updated with results.

Chris
RolandS888
Mar 27, 2009, 10:10 PM
Sounds really interesting Chris, any chance of posting some pics?
Also, what autopilot are you using and how well does it handle?
Cheers,
R.
airmcn_3
Mar 28, 2009, 01:14 AM
Sounds really interesting Chris, any chance of posting some pics?
Also, what autopilot are you using and how well does it handle?
Cheers,
R.


Roland,

I have experience with Kestrel, Atto and now a new Beta autopilot developed here in Australia. The system I am currently using is the Beta unit since we are still waiting on EAR paperwork to get finished for Atto. Hopefully very soon I will be allowed to bring my Atto into the country.

The Beta system handles rather well given I have not had a chance to tune it completely, it does not fly as well as Atto but is acceptable for hobby use. As soon as the developer says I can, I will post info on the new autopilot.

I am on a very slow internet connection where I am at right now so I will upload a pic later.

Chris
AUSUAV
Apr 03, 2009, 02:08 AM
Spektrum have now released a carbon fuse version of their 2.4 gear.
Check it out here (http://thebarnfloor.com/catalog/product_info.php?products_id=1289&osCsid=8e09a359dc5d52445fc5b175363bd603)

Certainly longer antenna leads to poke outside of the fuselage. I wonder if you can retro fit existing ones or it has differrent tuning to the standard one.

Cheers
Aaron
airmcn_3
Apr 05, 2009, 06:45 PM
Spektrum have now released a carbon fuse version of their 2.4 gear.
Check it out here (http://thebarnfloor.com/catalog/product_info.php?products_id=1289&osCsid=8e09a359dc5d52445fc5b175363bd603)

Certainly longer antenna leads to poke outside of the fuselage. I wonder if you can retro fit existing ones or it has differrent tuning to the standard one.

Cheers
Aaron


Thanks for the link.