2.4 GHz dead zones

[Ian Skeldon 1]

Hi all,

 

Couldn't help but throw in my opinion on this.

 

2.4 is here to stay and it offers huge benefits to modelling over 35mhz. However, I'm sorry to be so blunt but Flyilbroke and Dusty, Wakey, Wakey.

 

Sure, all pilots will experience the dreaded tip stall at some point, it's how we learn, again all pilots will loose orintation at some point, hopefully learning to relax at such a time and sqeeze some inputs to aid recovery of orintation.

 

But when an aircraft flies with undemanded inputs it's loss of radio control. Since the introduction of 2.4, crashes certainly seem to be more frequent and often with many leading to loss of the model all together.

 

In my opinion based solely on on-biased observation the problem seems to be that what would be a momentry glitch on 35Mhz, becomes a lock-out on 2.4Ghz.

 

I can't offer any explanation as to why or how this can happen, but I am not going to be told that I am not seeing what is played out in front of me. More models are crashing and the ones that crash all seem to be using 2.4 for control, so the sooner people stop trying to make excuses for this phenomenom and try to find out exactly why, the sooner we can get back to reliable radio links and crashes being caused by the pilot.

 

Finaly, as yet I haven't crashed any models due to loss of control and only one in the last few years through pilot error Doh....Please excuse any spelling errors, Happy, Safe Flying guys

Edited By Ian Skeldon 1 on 02/08/2010 08:18:27

[Wingman]

I fly Futaba 2.4 in my Zenoah powered aircraft because of the spark ignition and can honestly say I've never experienced any problem with it. However, all my electric aircraft fly with 35Mhz and mostly cheap xtal-controlled receivers from GC and although I do get glitches they are always very short duration and I have found that they are much more prevalent when the battery starts to wane ( a sign it is time to land!) so perhaps something to do with voltage level from the BEC and of course the other cause of glitches - pointing the aerial directly at the aircraft. I was wondering - would the WiFi sniffers you can buy be any good for checking RC 2.4GHz transmitter output?

[David Turner 5]

The snippet, below, is lifted from an American forum. .. posted a few days ago. The implications are obvious.

 

 

 

"The argument in congress was that WIFI internet connections are the wave of the future and that it needs much higher wattage/range than is currently allowed. It also seemed that it would be for licensed (IE: $$$$$) use only (RE: Comcast, Verizon Et Al). Seemed like they wanted to ban private WIFI owners from setting up themselves as ISPs, get the big companies to make more money and ruin the current 2.4Ghz range for all secondary users (if not ban them out-right). Remember that 802.11 WIFI and other devices use the exact same frequencies as RC radios.

Essentially, it could make all other 2.4Ghz equipment either useless or illegal.

If it would mean alot more money for the Gov't in licensing fees then it has a good chance of being passed at some point. Esp. since more people want universal wireless internet access than fly RC airplanes. "

Edited By David Turner 5 on 02/08/2010 11:52:30

[Ian Skeldon 1]

Hi Again,

 

Tony, before you buy a Hitec radio, just check how easily you can get service, repairs and extra receivers etc. I know of at least two shops that had customers waiting months just to buy the Aurora. That said, I haven't heard of any issues with this particular radio.

 

Myself and a fellow flyer recently did some very basic but very relavent testing of several radio sets. We found that on every make tested (5) there was never a problem when the model was close to us on the ground. We could blanket the tx antenna and force signal loss, as soon as we restored line of  site, the rx instantly re-connected.

 

Possibly a stupid thing to do but we then tried the same thing in a model in the air, the results were fascinating. Three of the radios connected again instantly or very quickly, one after about two seconds but it seems a long time, finally, the remaining brand took about 4 or 5 seconds to re-establish the link and we very nearly lost the model. Had we not been flying high up in each instance we would have crashed in two of the three  tests.

 

This I think is what is happening in cases where loss of control is happening. I susspect the rx arial type and orientation is a consideration, as is the tx arial orientation. I know very little about signal propergation but beleive that 35Mhz radiates more readily and thus doesn't loose the connection as easily. Now if only I knew how to resolve it.....

[paul@scc]

Everyday I wake up thanking the lord that Spektrauma became the ''in'' piece of kit. As this enabled me to buy a JR 9X 35 meg + two Jr Rx's for next to nothing from a new Spektrauma owner

[Biggles' Elder Brother - Moderator]

While having absolutely no wish to turn this into the futile "mine is better than yours" sort of argument, I have to say that I use Futaba 2.4 and have had absolutely no problems at all (touch wood ). I've been using the 8FG for all my flying for about 4-5 months now (and I fly at least 3 sessions a week, 5-6 flights per session) and I've have never experienced anything that looked remotely like signal loss or glitching.

 

Having said that several guys in the club have Spektrum 2.4 gear I am not aware of them having any problems either to be fair.

 

This is despite the fact that there is a major hospital (with a large A&E unit and dedicated ambulanace station on site) right next to our flying site - which would be a major user of 2.4 devices.

 

In fact all of the radio problems in our club (few as they are) seem to be centred around 35MHz users gettng glichting.

 

As I say - not meant confrontationally - just my experience.

 

BEB 

Edited By Biggles' Elder Brother on 02/08/2010 12:43:08

[Chris Channon]

Hi all,

Are the aerials on the rx a set length on 2.4  as per 35 megs?  If not i wonder if it would be worth adding a few inches ( my wife would be happy ! )  to the aerials and see if any loss of control goes away?

I seem to recall in a past mag that the carbon friendly Rx from Spekky has longer aerials.

 

As i say, just an idea.

 

regards

Chris.

[Tim Mackey]

No you cant do that.

The so called longer aerials are actually just small bore coaxial extension leads, the  active aerial remains just the little bit sticking out off the end .

[Chris Channon]

Okey dokey, as i said, just an idea, perhaps we could add a thinner length?

 

Regards

Chris.

[Wingman]

The post from DT5 is on the subject that worries me about 2.4GHz - our hobby has no clout at all in the grand scheme of things and we are using a piece of the spectrum that is free for all users so if "Big Corporation" lobbies their politicians with a view to taking over the free 2.4GHz spectrum to provide "super-WiFi broadband connectivity for all" or whatever, (which would give any politician a rosy glow) which is something governments keep promising, then we would find ourselves tossed aside without causing even a ripple of regret anywhere. At least with 35MHz we are using a piece of spectrum that nobody wants anymore and is internationally allocated exclusively for airborne model control and consequently is very well protected. The danger is that the manufacture of 35MHz kit will fizzle out as sales decline and if we ever get thrown off 2.4GHz we'll not have the means of going back to 35MHz or if we do the kit will be expensive even for basic stuff. Domestic kit and toys that use 2.4 at the moment are all in the "cheap as chips" class, manufacturers would just change to whatever new frequency might be allocated and people will just replace their cheap stuff. However it would be painful for us with our 300 quid trannies and 50 quid receivers to do the same with no guarantee that it wouldn't happen again in a few years time not to mention the fact that the new 'free' spectrum might be in the 5 or 10 GHZ region which I don't think would be much good at the distances we fly at (signals at that frequency get attenuated by atmospheric particles - moisture etc.).

Old Grumpy signing off

Edited By Wingman on 02/08/2010 18:28:44

[Ian Skeldon 1]

Mmmm now where did I put those 27Mhz sets.....

[Chris Channon]

Ian, now that seems like a good idea !!!!!

 

Timbo was your Fly Fly Hawk on 2.4 when it went in ?

 

I wonder how many crashes have happened due to 2.4 in the last year?

 

Please do not get me wrong here, i have been flying for over 30 years, first on 27, then on 35, now on 2.4,  never did have so many unexplained crashes in the past so what we need is someone to say yes or no 2.4 has a problem, and if there is a problem then it needs to be sorted.

 

I have been lucky, i have only lost one aeroplane on 2.4 as far as we can gather, due to no fault of the pilot ( me ) a genuine radio failure. Lots of glitches but only one loss.

 

2.4  is great, i can turn up, switch on and fly, but if it going to cost me an aeroplane then where is the advantage ?

 

Regards as always

 

Chris

 

 

[Tim Mackey]

Yes it was...but elevator failure ( mechanical ) was the cause.

[Peter Beeney]

   David,
        Yes, that’s very interesting reading. I’ve always felt that it’s possible that the frequency bands could disappear. However, I believe in Europe WiMAX is the way the trend is going and I think that uses the licensed frequencies. That’s only my vague supposition, though, and that may well be wrong. At the moment I don’t see the problem as being one frequency crowding, or of interference, rather that one particular brand might just have a serious? problem. In our small club the numbers of Spektrum and Futaba owners are about equal. Virtually all the Spektrum owners have had trouble whilst the Futaba story is a complete success. Not a single murmur of dissatisfaction.
   A couple of the lads recently visited a large club down the road a-ways, on a fly-in, and came back with the story that there were some quite significant concerns about the high mortality rate of 2.4 controlled models there. All Spektrum! Is there a chance that a club Safety Officer might begin to consider how Spektrum radio is used? After hearing their revelations I think it’s possible.
   I’ve seen many reports of how satisfied people are with the turnaround time at Horizon Hobbies. That’s good news, but in the old days Fleet and Skyleader were the same. But you only sent kit back to these establishments when it got broken, not because it caused unexplained crashes. Plus, as someone else remarked, why does so much radio gear have to be returned anyway? And does it not cross someone's mind sometimes at HH that an awful lot of gear is coming back through the door? From a beginner in the club who has just had a new set returned to replace his faulty one, this week, it seems there’s a standard covering letter; ‘No fault found, but as a precaution we’ve replaced it all anyway……’

   Ian,
       Also very interesting stuff. Were the 5 sets all different manufactures? If so, that must pretty well cover them all, at the moment, I’d have thought. How did you blanket the transmissions? I’ve contemplated doing this but I’ve never bothered. I thought that I’d try a tin can over the aerial to start with. I thought it might be a red herring simply because, once again, it’s only one brand that has a problem. I’m not entirely convinced about the aerial orientation always being the suspect, too. In my incident the model was in front of me, probably less than a hundred yards across the other side of the strip and about a hundred feet high when it suddenly decided all on it’s own to roll on it’s side, do a u turn and go straight in. At full throttle. When we checked everything afterwards it was all ok, including the throttle close on loss of signal function.

   Wingman,
          Is it possible you could confirm that you are using the BEC on the ESC, as opposed to a separate UBEC, in your electric models?                  PB

[Wingman]

Yes Peter I only use the ESC BECs. And as a matter of possible interest on this subject I use a "Sky Assistant" vario in my AVA glider which 'talks' to me over a UHF radio link and quite often warns me of low voltage - set to warn at 4.7volts - when manoevering with the motor powered up and that ESC is a Castle Creations Phoenix 60 so it's no 'cheapie' . My electric planes all use a variety of HobbyWing ESCs from the Big Fish.

[Ian Skeldon 1]

Hi Peter,

 

Yes radios tested were Multiplex, Futaba, JR with a Corona module, Hitec and Spektrum.

 

Signal blanket was as simple as shrouding the aerial whilst also standing between the model and TX, very close in front of the tx, Some were reluctant to loose signal and were very quick to regain the signal once shielding was removed, a couple not so good.

 

We also did a test whereby a powered glider was flown as far as I could see, then instructions relayed from two spotters using binoculars, the results were good for the first couple of tests nut the third proved to be the end of that particular test as the radio ran out of range before the old mark 1 eyeball.

 

I can't back any of this testing up with any electronic measuring or extensive knowledge, but as I don't use bench equipment when I am flying I can't see how that might change my opinion anyway. As I don't wish to influence anybody else as to which make of radio they should buy/use, all I can say is that several posts here indicate that people are finding the same issues/concerns at there clubs and flying sites. A few people seem to  blame their flying rather than consider that the radio they have bought could be deffective in some way.

Edited By Ian Skeldon 1 on 02/08/2010 20:33:06

Edited By Ian Skeldon 1 on 02/08/2010 20:34:22

[Ian Skeldon 1]

Whilst here I have to mention that we have found issue with the use of Nimh and are moving over to the use of Lipo with good quality Ubecs and/or the use of A123 or Life cells.

I'm not saying that you should all do the same, but if you do have a crash caused by  loss of radio link and your using Nimh, check/test your flight pack under a simulated load and check each cell individually, this might reveal a possible cause in some cases!

 

 

[andy watson]

I've really tried not to get involved in this thread, but it must have reached the point where people have to look at the equipment being used and ask a question about it. 

 

Don't get me wrong, I know thousands of people have used the brand in question without problems, but look back through the thread and other threads about receiver issues and you must begin to see a pattern.  The funny thing is that once again Horizon Hobbies will get awarded the best distributer award in the RCM&E poll on the basis that they repair/check out so many receivers/transmitters for free and promptly that people seem to think this is good service (and yet ignore the value of all the bits left scattered all over the countryside).  I have no idea how to contact Ripmax- because I don't experience "dead zones", brown outs, slow rebinding, or need to check for firmware updates or whatever.

 

I understand people have a lot of money invested in their radio gear, but if I were buying a new set I would not dream of looking towards Spektrum.

[Tim Mackey]

But thats not really proper evidence of an issue - more subjective opinion.

Considering the HUGE numbers of people worldwide using Spektrum gear ( way more than the other major player ) then its obvious that - proportionally - more could experience a problem. Couple that in with the fact that many problems are eventually traced to user induced errors - be that poor installation, poor power supply, incorrect operation such as poor Tx aerial alignment  etc etc . Then add in all the many many satisfied people who have no complaints at all about the gear - and I think your statement that you would not even dream about buying Spektrum just doesnt stand up - apart from it being your perfectly entitled  personal opinion only.

I too have no wish to start a "mines better than yours argument" but feel obliged to defend Spektrum gear, purely as a very satisfied user with many many hundreds of trouble free flights on over 30 different models.

Im sorry, but frankly , the only "pattern" I see is one of operator error in very many cases.

[Ian Skeldon 1]

Hi Tim,

 

Okay I won't get drawn into which is best or whatever either, there's  simply no way that argument has a conclusion.

 

I would like to leave you with this simple thought though, most of the operators I have wittnessed having their operater errors, have it whilst using a particular brand of radio. You might well argue that would be the expected outcome based on percentages of sales, I might even agree with you if I was armed with accurate sales figures. But try to think slightly more openly and compare the number of operater errors happening with 2.4 compared to 35Mhz use.

 

Of course more people are now using 2.4, but I can recall many, many days spent flying along with other flyers and we would often suffer from glitching, but I never saw anything like the ratio of crashes as I do now.

[TonyS]

Well chaps, as always a polite, but opinionated debate as I'd hope to see on this site.

It is a blog though and opinions do have their place.

 

With subjects like this there are so many variables and so little hard evidence (even the tests cannot really be held out to have been carried out in controlled conditions).

I feel obliged however to defend myself here. I know that Timbo, you did suggest a return of my Tx for testing which I will be doing. (A chance for me to test the incredibly good service of HH!). Flytil broke, Dusty and now Timbo have all now suggested that in their opinion the problem is probably caused by my poor set-up, incorrect use of the tx (i.e. pointing the aerial at the plane and/or pilot error.

 

I'll just say this, not because I'm precious about what people think of my capabilities, but genuinely because I feel everyone needs to be in possession of the facts on this one - there's a lot of money at stake here, not to mention the misery of losing a favourite model..

In all instances:

I always fly with the aerial at 90 degrees to the tx - no matter which way I face the only time the antenna could be pointing directly at the aircraft would be if it was directly overhead. In every case where I've experienced control loss, the model was at least a couple of hundred meters away. (There may be a range thing going on ?)

I have experienced the problem on models using the single Rx AND ones with a secondary antenna - in the latter case with the antenna positioned at 90 degrees to each other as far apart in the plane as space allows. 

In all cases, ALL control of the plane is lost - no control surfaces OR throttle (which to me rules out pilot error - I find it hard to fly by telepathy alone!) 

 

As I've lost one of the models completely then a test of that particular Rx is impossible. I'll send them a couple of the others though.

In the meantime I'm going to take the plunge and move to another brand. To be honest I've lost confidence in the set I have. 

 

I don't want to start a witch hunt - I have no interest in this whatsoever. I do however have a valid concern that I feel needs to be shared. To those who have never had a problem that's excellent, but I'm wondering if there aren't a disproportionate number that do have a problem.

 

I understand the argument that more people fly this brand than any other therefore there will be more problems but there is also an argument to my mind that says if you spend £280 on a Tx it should be fit for purpose and i don't accept that I might be one of 1% / 5% or whatever the number is, that simply "have a problem" - remember this has cost me THREE aircraft so far. One a total loss so no recovery of parts at all. Very expensive. 

[Tim Mackey]

Thats all very valid Tony - and I completely understand your actions.

I should add that I did not mean to infer that you ( or in fact any particular individual ) was to blame - my comments regarding many problems being operator induced was based on the very many instances that I have seen and heard of via several forums, extensive field experience, and flying colleagues.

I was merely ( badly it seems ) trying to counter the sometimes wild statements made along the lines of " loads of people are having issues with brand X gear" therefore it must be rubbish. Of course there will be genuine issues, components fail and so on - thats life.

Its a pity that you have lost confidence in the equipment, but I sincerely hope you find a solution in the replacement

[Tim Mackey]

Posted by Ian Skeldon 1 on 02/08/2010 23:38:50:

Hi Tim,

 

Okay I won't get drawn into which is best or whatever either, there's  simply no way that argument has a conclusion.

 

I would like to leave you with this simple thought though, most of the operators I have wittnessed having their operater errors, have it whilst using a particular brand of radio. You might well argue that would be the expected outcome based on percentages of sales, I might even agree with you if I was armed with accurate sales figures. But try to think slightly more openly and compare the number of operater errors happening with 2.4 compared to 35Mhz use.

 

Of course more people are now using 2.4, but I can recall many, many days spent flying along with other flyers and we would often suffer from glitching, but I never saw anything like the ratio of crashes as I do now.

 

Ian. I do try to be open minded - but again, the case scenario you paint doesnt really stack up again.

You say.....

" Compare the numbers of operator errors on 2.4 versus 35Mhz."

Hard to do because of all the people who I now regularly fly with about 90% are on 2.4

The few remaining 35Mhz folk are all seriously considering moving to 2.4 because ( in their usual words to the effect of ) ... " I get glitching on my electric stuff, I was shot down last week", etc. I can honestly say I have never personally known of a single issue with 2.4G radio ( of any brand ) that was not traced to operator error of some sort - and I include myself in that. I do have a few bad memories of problems with 35Mhz stuff though. Now this is just my personal experience - not global fact

Therefore I can only reply to that point -  No comparison - 35 Mhz was far worse.

As to why you are experiencing more "crashes" with peeps on 2.4 - thats a bit more difficult to pin down. Could it be that todays fliers and models are far more adventurous than the 35Mhz brigade...I am not saying thats the case - just proposing it as possible reason. Properly setup Spektrum gear has a far quicker recovery time in the event of either signal loss, or brown out than any of my previous JR 35Mhz PCM gear.

[Biggles' Elder Brother - Moderator]

I have to say my personal experience aligns with Tim's on this - except my club is far from being 90% 2.4. In our case 2.4 flyers are still a minority - about a third I would say. But I reiterate the experience I outlined above, its the 35MHz guys who have all the problems - particularly those flying elecric power. Those of us flying 2.4 (be it Spektrum or Futaba) seem to be fine with any "incidents" that do happen being clearly explicable by other reasons than radio problems.

 

One thing - I always orientate my aerial in the 45 degrees to the transmitter setting - that way its more or less straight up relative to the ground - and I'e never had anything that looks even vaguely like "lock out" or "brown out". 

 

But like Tim I can only relay that as my individual experience. TBH I don't fly at a lot of different sites - so maybe its a site specific thing?

 

The feeling of having no control whatsoever over the model is a sickening one and I can understand would make people feel wary if this has happened more than once in the recent passed. But this is a very difficult problem to pin down - there are so many variables;

 

1. The Tx/Rx link - i.e. radio hardware failure

2. The quality of the installation of the radio gear

3. The material from which the model is made

4. The possibility of external "interference"

5. The flying site

6. Range Issues

7. Signal blocking - possibily aerial orientation issues

8. The possibility that non-radio failure may be responsible - e.g. mechanical failure

9. Good old fashioned "pilot error"

 

And I'm sure thare are others I've missed out. The worrying thing of course is when so many experienced fliers start to say "Something is wrong" - then we have to take it seriously and listen to them.

 

BEB

Edited By Biggles' Elder Brother on 03/08/2010 11:11:48

[Delta Whiskey]

I have to agree with Tim in that 2.4 is much better than 35mhz.

In my short 2 years with this hobby, I've been using both since day 1.

 

The worry and hassle of checking peg boards, and the feeling that someone setting up his models in the pits behind the flight line might switch on this TX while my model was in the air always worried me !

 

My club is 90% 2.4 and to my knowledge we have not had any crashes that were down to radio links while on 2.4 ghz. I have however experienced glitches myslef on 35, none on 2.4.

 

I still use 35 on one model and up to very recently on my pride & joy heli. The only reason I'm still using 35 is because the price of a new 2.4 RX puts me off, when I have a perfectly good TX & RX to use on 35. When I do get another RX though 35 will be gone !

 

On the subject of Dead zones, as was originally started in this thread, if the same model and TX can be flow at another site / area and is ok, then you will know it's a localised enviromental issue !  (I did mention this is an earlier post) - not been answered yet I believe?