Bill Wood Posted July 21, 2009 Share Posted July 21, 2009 I have read somewhere in the Forum about loss of control using 2.4 gHz and flying near trees was mentioned. Also I have witnessed, at the local club site, two crashes on the same day whilst flying near trees. The pilots reported loss of control and both were using 2.4 gHz. This started me thinking -- I have many years of experience using marine radars and the S-band radar works at a frequency of 3 gHz. Vegetation and in particular wet vegetation reflects radar energy. Could it be possible that trees in full leaf and especially when wet will reflect and scatter transmissions on 2.4 gHz ? If this is the case could such scattering of the signal be sufficient to cause weakening of the received signal and subsequent loss of control ? Perhaps someone with technical knowledge will be able to judge if 2.4 gHz signals from our TXs are capable of bouncing around like radar energy. It will also be interesting to hear from anyone who has experienced glitches or loss of control using 2.4 gHz when flying near trees and whether the trees were in leaf and/or were wet.Having said all that, I attended the Weston Park show in June on the Saturday and I saw only one crash near the trees and that appeared to be the dreaded depth perception issue, not loss of radio signal. Quote Link to comment Share on other sites More sharing options...
Ian Jones Posted July 21, 2009 Share Posted July 21, 2009 Losing control near trees is quite common whatever the radio system . Actually I think I undertsand what you are getting at and since you asked here's an entry from my flying log. (Which incidently is an MS Access database inspired by some log sheets that were printed in RCM&E a few years ago): "Calm & flying very well on inverted pass right to left. At far end elevator applied for half loop to upright flight but failed to pull out and slow spiralled into adjacent field. Nose first impact & extensive damage. Cause unknown, poss's = pilot error, battery failure, signal loss, airframe failure, servo arm/fixing failure. Elevator servo and portion of tray ripped out & servo arm broken off, cause or effect? Signal failure - failsafe should have neutralised controls so no spiral? Battery failure, possible (due to cold conditions around 4C), good charge when run afterwards though. Pilot error, doubtfull but cannot be eliminated." This event happened on 28/01/09, no leaves but pretty well everywhere was wet. The aircraft was an EP Kavan Partenavia P68 Victor which I had been flying for nearly 3 years on 35mhz and 19 days on 2.4ghz (Assan module in Eclipse 7). I had not experienced any problems up to this time. Whilst the style of flying wasn't really what the P68 was intended for it was a sequence I had done numerous times before. Supporting evidence for your theory? I don't know but there you have it. Though aircraft have been lost through unknown causes on 2.4 at our field (perhaps AKA pilot error), I would add though that it is common practice to land with the approach being between trees and I 'm not aware of any incidents where 2.4/ trees could be a contributory factor. Quote Link to comment Share on other sites More sharing options...
Brian Parker Posted July 21, 2009 Share Posted July 21, 2009 Bill, If you search you should find previous threads on this Forum on reflected/masked 2.4Ghz signals and the need for correct orientation/polarisation of antenna. Our signals are low power so signal reflection with correctly setup antenna (both Tx and Rx) should not be a problem. Contrary to popular belief a stronger signal could cause more problems when flying in a restricted location. Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted July 21, 2009 Share Posted July 21, 2009 Good advice about the aerial orientation Bill - check it out and ensure you are positioning things correctly.Theory does indeed suggest that "wet things" can affect the 2.4G signal - and I not saying it doesnt /couldnt /wouldnt if you get my drift. Hoewever, our power flying site layout, means that nearly all take offs and landing approaches involve flying close ( indeed I usually fly in-between just for the heck of it ) to trees, and I have never had an issue in 3 years use of my Spektrum stuff. Quote Link to comment Share on other sites More sharing options...
Fog Dart Posted July 21, 2009 Share Posted July 21, 2009 I went flying at a flying club as a visitor not long ago and a guy was using an Assan set up. He complained that his plane froze with all surfaces at their extremes every now and then. He demonstarted on the ground and after about 2 minutes it happened with him stood right next to the model. What make of radio equipment were the other guys using when they had problems? Ive had no issues whatsoever and im using Spektrum. Quote Link to comment Share on other sites More sharing options...
Bill Wood Posted July 21, 2009 Author Share Posted July 21, 2009 Thanks for your input guys. I'm not saying that using 2.4 G near trees is a problem. Hopefully it isn't. I'm just trying to find out if there have been other instances and getting feedback. So far I am still using 35 megs and I'll probably have to wait until Santa brings 2.4 gHz unless I can sell my Astro Hog, but that's another story. Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted July 21, 2009 Share Posted July 21, 2009 Bill -Very interesting Very worrying but I have a couple of questions based on replies so far (in case you didn't know I have an issue with a module conversion from 35 mHz ) It seems that recognised quality outfits -You know them both -don't seem to have problems (probably why they aren't that cheap) .What I don't get is how these cheaper modifications have the "approved" sticker on them -CE . Who approves them I wonder ? I have spent an inordinate amount of time recently with my Corona conversion & to be blunt I've gone back to my 35 mHz original set up . I daren't risk the mod ! Not on a valuable (to me ) model . Do I fly where there are no wet trees or what . I've never had problems with the old fashioned gear not even once -Honest ' I,m beginning to think I'm a sucker for all the hype about 2.4'conversions. Having said that I'm extremely happy with my Futaba T6EX & now have two Rx's -606's. In other words I have two models that I dare fly . Four actually 'cos I have a cheapo Tx/Rx combo which has worked so far plus my Optic converted back to 35 mHz. Over to you Myron Quote Link to comment Share on other sites More sharing options...
Bill Wood Posted July 21, 2009 Author Share Posted July 21, 2009 Myron, Perhaps we're getting a bit off the thread with 2.4G conversions. You mentioned old fashioned, well I think fashion has a lot to do with folks rushing to 2.4G. If your happy with your 35 meg gear and the right things happen when you waggle the sticks then stick with it. I remember somebody saying the same about 27 megs. Don't worry about the trees. The experts don't think it's a problem. Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted July 21, 2009 Share Posted July 21, 2009 Bill You are so right .I'm not an arborologist anyway (maybe a bit wet) . My 27 mGhz flying was all done down Cornwall at the peak of so called CB interference !( I did it too ) No probs ! Quote Link to comment Share on other sites More sharing options...
Dusty Posted July 21, 2009 Share Posted July 21, 2009 What Assan rx's are these guys using??? I have been flying trouble free with ASSAN rx's on all my models for some time now! I have "yet" touch wood experienced any problems with the modules and rx's... Are they short/long Ae? Personally i use the short Ae and as I say not a problem, Assan does have a park fly/full range and they look similar? Might be worth cheacking up? My 2 p being a Assan user and have yet to fault it, easy to bind, cheap and WORKS... I know loads more people using ASSAN & have never had a prob! I dont mean to sound like a sales rep... Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted July 21, 2009 Share Posted July 21, 2009 With the digital nature of 2.4GHz equipment I'd have thought there would be less of a problem as corrupt frames should be ignored - although I don't have any familiarity with the budget systems so they might differ. However, I'll take Brian's advice and look at some of the other threads as this has got me wondering... A word of warning for those of us using modules and swapping systems on a regular basis - I noticed that the 35 MHz module on my FF9 was intermittent last time I was preparing to fly - substituting my Jeti module gave the same results when wobbling the module. Although even magnified inspection didn't reveal any definite cracking around the pin connections on the PCB in the transmitter, resoldering them has cured it but it's something to watch out for - it probably explains the momentary glitch on one flight the time before...newly added pre-flight check needs to be a module wobble! Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted July 21, 2009 Share Posted July 21, 2009 We have a few trees around our site and a handful of fliers on 2.4 (Futaba and Spektrum) no problems so far with any of the radios. Have seen a few tree magnet incidences though but these don't seem to be selective between 35 and 2.4 Quote Link to comment Share on other sites More sharing options...
John Horsfield Posted July 22, 2009 Share Posted July 22, 2009 The only problem Ive ever had with interference from trees is when Ive crashed into them... I guess it could be a radio problem or failure of the airframe, but the fact is sometimes you just have to swallow your pride and admit that you made a mistake, even if your not 100% sure what the mistake was. Lets face it, the slightest error in our hobby can be disastrous. Im always very skeptical about complaints of interference, especially when they supposedly caused a crash, its easy to blame the radio gear... I suspect (to be proven wrong of course!) that wet trees cause absolutely no interference with 2.4ghz. Quote Link to comment Share on other sites More sharing options...
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