WELL THERE'S YA PROBLEM !

[Chris Bott - Moderator]

I don't agree BEB. If the quicklink was slightly loose then the wire could very well have pulled through it when left aileron was applied at some point. Any slight twisting of the link could well have jammed it on the wire again, meaning that when the servo centred, it would push the right aileron up...

[Chris Bott - Moderator]

Oh and as a Spektrum user, the receiver installation sounds fine. The aerials on the Rx and on the satellite are mounted directly on them. So I'm assuming that the Rx was mounted horizontally, with its aerials horizontal, and the satellite was the requisite distance away and mounted perpendicular to the Rx, with it's aerials perpendicular to the Rx's aerials.

[Biggles' Elder Brother - Moderator]

Posted by Chris Bott - Moderator on 04/09/2013 12:21:53:

I don't agree BEB. If the quicklink was slightly loose then the wire could very well have pulled through it when left aileron was applied at some point. Any slight twisting of the link could well have jammed it on the wire again, meaning that when the servo centred, it would push the right aileron up...

Well yes that's possible but John uses the expression "disconnected" and describes it as "come loose" given that I really can't see it jaming tight enough to displace a control surface against the pressure of the airflow sufficiently to make the model uncontrolable.

Also he says it was flying straight and level immediately before violently rolling right! How can we explain that via a loose connector?

The truth is of course, we'll probably never know the cause - but for my money that info means that while the connector (or non-connector!) could have done the deed, it moves down the list from being number one suspect!

BEB

[john melia 1]

Phoned horizon hobbies and got talking to a very helpful guy , I explained that if the receiver could be checked out then thats one more piece to the puzzle in place , he told me to parcel it up and send it off to them , so I have , will let you know the outcome

[Pete B]

John, I hate to raise the possibility of pilot error, Heaven forbid, but in the two posts here where you describe the crash, you mention 'I did manage to shut the throttle' and 'Because of the violent nature of the spacewalker crash', I'm wondering whether you were blasting around at full tilt at the time?

I ask this as, in the earlier video of your Wildcard maiden, it seems to me as if you spent the entire flight at full throttle, which has to be a recipe for the model getting ahead of the fingers....

I'm pretty sure both these models should cruise very comfortably at half-throttle, which gives you a chance to react to anything occurring and time to correct any unintended stick inputs.

If that's the case and you were flying the Spacewalker in the same fashion, then 'dumb thumbs' is just as likely a cause as a radio problem, IMHO....

If it's not, and Horizon find a fault with the Rx, then I'd better apologise in advance.....

Pete

[john melia 1]

Honestly pete I would be the first to hold my hands up and say it was pilot error , no shame in that in my book , but I can confidently state this was definately not pilot error , as I say I was doing big lazy circuits throttle round about half when it happened , as it tipped to the right there was no control , when I managed to turn it control was very erractic almost intermittent , while not being enough to get it back on the ground , I've got a feeling the bec has something to do with it , going to wait for the results on the rx first though

When I say I managed to shut the throttle I pulled the stick back to idle , but because of the distance from the model I'm not sure anything happened , also the distance was no further away than when I fly the sedona or the su37 , hopefully I can shed some light on this because its becoming expensive , as for the wildcard it had just barely left the ground when it happened , with all previous flights being fine

[John Roberts 9]

Hi John,

I had a very similar thing happen to me a couple of months ago. My Rx was a Spektrum AR6200 and so I sent it back to Horizon Hobbies asking them to check it over for correct functionality.

A couple of days later I was very shocked to receive a polite email back from HH advising me that they were unable to check the Rx because it was counterfeit.

To my uneducated eye it looks like the genuine article but some research on the web enabled me to spot the subtle differences between the real one and my fake.

I am not suggesting that yours is a fake but its worth having it checked out.

Cheers,

John

[SkippyUK]

Don't know the model but is wing held on by bands?

If it was and is so unscathed, were there enough of them or did one or more break on one side.

When I saw a trainer with 6 bands go in, the wing was far more damaged and almost broken in two - just a thought in a different direction from Radio seeing as you had some kind of control and radio re-connection normally takes several seconds....

Skippy

Edited By SkippyUK on 04/09/2013 20:57:51

[Paul Marsh]

Is it an original Spektrum receiver? You can tell if it is, by there being a sticker with Horizon Hobby and fake ones have blue sticker with Chinese writing on it. Check now.

[john melia 1]

Cant check paul I've just sent it off to horizon hobbies today , skippy the wings are held on with nylon bolts

[Ausferret]

Aileron servo glitch/failure?

I think I go along with the majority, these fittings are OK if installed correctly (i.e. loctite and preferably flat on the wire) on light weight foamys. 30 or larger glow powered aircraft I am not so sure.

[Gordon Tarling]

What many appear to have overlooked here is what happens if an aileron linkage is disconnected in flight - it will naturally tend to float upwards and cause that wing to drop. If you need proof of this, take a look at many of the larger biplanes around which have no servo on the upper ailerons and are merely pulled down by a cable from the lower aileron. They will either float upward or use a very light spring to assist them. Reason? Higher pressure under the wing than on top.

[john melia 1]

Phoned horizon hobbies today about my receiver I sent back for testing , the guy said its been tested and no fault was found, but for my piece of mind they are sending out a new one when theybget them in , I have tested the bec , and switch while connected to the battery , with a multimeter and all seems fine , even after wiggling, bending , tapping the wires , shaking the switch ect .

So the only other variable is the servos , what wwould be the best way to test them to see if one or more is faulty and thereby drawing too many amps causing the bec to shut down ?

Something definately went wrong on that particular day and I have to find out what it was

[Mike Etheridge 1]

I know of two recent incidences of model plane crashes where both large planes have piled in following complete loss of control of the 2.4 ghz radio. The suspicion is that the radio in both cases received interference and that the receivers did not recover in time to avoid the crashes as would have been the case with 35 mhz radio. However nothing has been proved to date. Both pilots were very experienced.

I am glad to date I have not purchased any 2.4 ghz radio.

MJE

Edited By Mike Etheridge 1 on 12/09/2013 10:12:16

[john melia 1]

Thanks mike its doing me no good in the confidence of equipment department thats for sure

[Codename-John]

It always makes me wonder that they never find anything wrong with the rx but replace it anyway, why would you replace something if you were sure there was nothing wrong with it, if they admitted a problem would that make them liable for any claims that might arise from damage caused due to faulty equipment ?

[Biggles' Elder Brother - Moderator]

Posted by Mike Etheridge 1 on 12/09/2013 10:11:35:

I know of two recent incidences of model plane crashes where both large planes have piled in following complete loss of control of the 2.4 ghz radio. The suspicion is that the radio in both cases received interference and that the receivers did not recover in time to avoid the crashes as would have been the case with 35 mhz radio. However nothing has been proved to date. Both pilots were very experienced.

I am glad to date I have not purchased any 2.4 ghz radio.

MJE

Edited By Mike Etheridge 1 on 12/09/2013 10:12:16

Well - here I'm not going to mince my words or dress this up, I'm going to tell like I see it and that might upset a few people!

1. the potential for interference on 35MHz was almost infinitely greater than on 2.4GHz. I've seen a lot more planes go in due to what was undoubtedly interference on 35MHz than I think I will ever see (even as a credible potential cause) on 2.4 GHz in the rest of my life.

2. All of the evidence (note, evidence not hearsay, whispers and rumours) tells us the 2.4GHz gives us the most sophisticated, multiply redundant - and so strongest and safest - link between us and a model we have ever enjoyed. The data validation, channel hopping and error checking that a 2.4GHz system does, thousands of times every second, is beyond anything we could ever have imagined using 35MHz technology.

3. The production techniques used to manufacture and test of modern 2.4GHz is likewise much more controlled and stringent than anything the makers were using in the days of 35MHz. The large scale integration of industry standard chip sets means that much bigger "up-front" development investment and validation can take place.

Now for the really controversial bit. It is my considered personal opinion that the overwhelming majority (I'm almost tempted to say "virtually all"!) so-called "interference" incidents on 2.4GHz are due to either poor installation or just good old fashioned pilot error.

Let's bite the bullet and mention "the elephant in the room". Spekky have been the company to come under the hammer most of all on this - with Futaba and JR having a relatively "clean record" - why might that be? Well my view is that Spekky has become the brand of choice for new and relatively inexperienced pilots - result there are a lot more poor Spekky installations that are not properly range checked etc out there than is the case with Futaba and JR - simple as that.

We Futaba/JR jockeys mainly date back to the "bad old days" of peg boards, being "shot down", "glichting electric models" and "frequency scanners" to do interference checks. Yes that was all part of the joy of flying 35MHz - remember those days? They were brought up to always "doubt the radio", so they are particular, their installations are done with great care. Result - statistically fewer so-called "radio problems". 2.4GHz may be the best thing that has happened to this hobby in a long time, but sadly its not bullet-proof - nothing is. And its not proof against poor installation and inexperienced flying.

I have watched many relatively new pilots shout "locked out, I have no control", or "interference" as they watch their model drop to its death. Afterwards nothing will shake them from their interpretation that it was a "radio failure". What it was in reality was just a good fashioned stall! No elevator response equals radio failure? No, it is just aerodynamics - nothing wrong with the radio. But they can't be convinced of that. Why? Because the rumour mill has planted the seed in their minds "There are question marks over Spekky kit" or "2.4 isn't reliable" The specious idea is that its subject to some random, non-casual, intermittent, mysterious fault that apparently no one can reproduce under controlled conditions. Very strange.

And so the rumour mill is fuelled, and we get posts like this. Hearsay, dignity-saving blame-shifts and speculation become the basis of serious debate - all of which, in my view, makes no technological or scientific sense at all. Its so easy to blame the radio - especially when others are doing it and its a relatively new technology. The reality is almost certainly that the cause lies much nearer to home and we'd all do ourselves a big favour and take a collective step forward if we could realise that.

OK - I've got that off my chest. I know it makes me sound like a grumpy old man - but I think its time someone "grabbed the bull by the horns", stated a few unwelcome facts and tried to put this urban myth to bed!

BEB

PS - Just in case your wondering am I just defending Spekky? - I'm not primarily a Spektrum user - indeed those that are Spektrum users may have witnessed me from time to time having a "joke at their expense". I use mainly Futaba, but I have a DX6i (which I don't particularly like but it works fine) for BNF type models and use on the simulator. So my comments above are borne out of a genuine desire to simply see what I consider to be some common sense in the wider debate on reliability of 2.4 systems generally.

[john melia 1]

Thanks for the info beb , In my case it doesn't seem to be the tx or rx at fault , but I still stand by my argument that it was most definately not me either , I had already completed 4 or 5 big circuits with no problems whatsover , the spacewalker is easy to fly , it basically flies itself when straight and level ,

I have a homemade su37 which is by far and away more difficult to control , both from stability and orientation pointof views , and I can fly this no problem , Iin fact we had three up at once on sunday , making for an exiting few hours.

The spacewalker lost " something " when flying straight and level , either mechanical , or electrical, as I've stated in the post above , the rx has been tested and found to be ok , dont know why they are sending a new one if the original one is fine , anyhow , thats the rx out of the loop , the tx is ok , otherwise my other models would now also be binned

I' ve tested the bec , switch , and battery and they all check out as stated in one of the above posts , so could it be a faulty servo drawing more amps than it should and shutting the bec down ? How do I test the servos , would I need a servo tester , or just connect everything up and apply a small hanging weight to the servo arm while testing .

[kc]

After a number of 2.4 Ghz problems at my club of models spiralling in -all in the same way and in the same area which is only a moderate way away - we began to suspect interference. But our current thoughts are that low Rx battery may be the cause or perhaps being end on to the Tx aerial. However as several of the models used BEC from the motor Lipo presumably they could not be due to low battery but maybe end on to the Tx aerial.
Some research as to how people orientate their aerials and also how they hold the Tx is the next stage for our club.

2.4 and also digital servos are reputed to need more battery than we needed on 35mhz. There has also been a rumour that Eneloop batteries for the Rx are not up to it for digital servos. Can anyone confirm this?

Edited By kc on 12/09/2013 13:35:26

[Mike Etheridge 1]

BEB,

I cannot dispute any of the points you make above and I am reluctant to give too much detail of the two crashes. One pilot I know extremely well the other I do not know at all except that he is a show pilot. The latter's radio was checked by the manufacturer and found to be without fault.

There has been a suggestion that there might be other users of 2.4 ghz including the military plus other devices in the location that might be sending out strong signals that could intefere with models?---who knows I don't? In the same location I have had 'hits' on 35 mhz but have never lost a plane as a result. The last time I did lose a plane from interference was on Epsom Downs in 1976. In this case the radio was 27mhz.

However I wonder if any research is being carried out currently on potential problems with inteference on 2.4 ghz by the manufacturers?

MJE

 

 

Edited By Mike Etheridge 1 on 12/09/2013 13:32:09

[Bob Cotsford]

I didn't want to say it earlier, but the 'large lazy circuits' bit did make me wonder how far above stalling speed the model was flying. Dropping a wing and subsequent soggy controls smacks of low speed to me except.....

 

The other week I was given control of a large Gilmore Lion for a try-out, but when I tried to roll the model it dived off to one side. Trying to steer resulted in some very peculiar handling but the model was landed ok thanks to the skill of the pilot (not me!). The reason for the wierd handling was that one aileron servo mount had failed allowing that aileron (+ servo) to flop about. I can well imagine one of those screw connectors coming loose giving very similar symptoms as it intermittently slid and gripped.

 

On the subject of 2.4 interference v installation - I fly FrSky gear which gives low signal level warnings, and it has proved very difficult to get an IC installation where the signal level doesn't drop off in some orientation of model to transmitter.  Add a larger than average engine into the mix with extra wiring and batteries for ignition and I can well believe flyers experiencing odd losses of signal.  2.4 installations are a LOT less plug'n'play than 35 was.

Edited By Bob Cotsford on 12/09/2013 15:29:09

[john melia 1]

Bob by large lazy circuits I mean j u st below half throttle , nowhere near stall speed , with the skywalker having an sc52 up front , it was flying straight and level , it would have flew like this basically hands off , then it all of a sudden banked hard left with no apperent control , until I managed to turn it towards me , but control seemed very intermittent to non existent at that time.

The orientation from tx to model was no different than the previous 3 of 4 circuits

[Jamie sawyer]

Personally by what your saying pilot error is out of the question.

The fact you sent the reciever back and they have tested it and say its fine could be just good customer relations. Or they may just not want to admitt a fault....its everyones guess but I'd have to go with the fact it was tested out ok.

If your battery dropped circuit and you lost power, in what way would that act on your servos etc ?

I have a 2.4 ghz Futaba Fasst system and the main reason why I left RC Helicopters is my first flight with the 2.4 ghz gear I had radio lock out. I think mainly that was due to poor orientaion of the ariels on my gear. I haven't had any issues with it in my Planes but thats maybe because I have learn't the hard way by the loss of a £600 helli.

Maybe you can remember during your incident, exactly the chain of events. If I have radio lock out my system on the Futaba takes a 2 to 3 second delay to regain connection then all is good again. That is exactly what happened with my Helicopter. I was hovering at 30 meters alt.....It held there and I had no input....the helli started to bank right falling out of hover.......it kept tipping right and loosing alt.....at abot 5 meters of the ground I remember getting input again but it was curtains by then and going in hard.......On full inspection of the crash all looked totally perfect ( Other that the tangled mess of helicopter and blades)and radio worked flawless. Following the result I posted on RCHELLIADDICTS which I am a member on to and it was confirmed that I hadn't been alone on this adventure. That will be about 5 years ago and I had lost confidence in my 2.4 ghz gear. I had 4 years away from rc but up till now with a good 2 hours of flying time on the same radio set I have had no incident ( Touch wood )....

Unless you had some clear indicators your just going to be playing a guessing game, or if your lucky you may find a fault such as stripped gears in a servo or something alike. I just binned a couple of 148 servos because they were acting a bit odd to say the least!!!

Good luck with it all and sorry for the loss of the aircraft

Jamie

[john melia 1]

I'm basically stuck between a rock and a hard place , I have the jodel d-120 about 85% finished , and I've re-ordered another spacewalker 2 , but I dont know whether to install the new spektrum rx when it arrives , or sell the dx7s with the new rx on ebay and try something else .

Having said that I have spektrum gear in my faithful sedona and its never been any bother , and I have spektrum gear in my t-rex 600 nitro pro , which is now in bits , but that has nothing to do with electronic failure of any kind

As I've said , it seems everything other than the servo's (which I havent as yet tested ) has checked out ok , I'm going to get shot of the bec and use a life battery , and bin the switch for a new one , even though they work fine .

Other than servos , and the fact that an aileron control rod was disengaged from a sevo screw connector which was noted on post crash inspection I'm at a total loss , unless there was some sort of interference present at that time .

[Biggles' Elder Brother - Moderator]

Posted by Jamie sawyer on 12/09/2013 18:52:53:

Personally by what your saying pilot error is out of the question.....

....I have a 2.4 ghz Futaba Fasst system and the main reason why I left RC Helicopters is my first flight with the 2.4 ghz gear I had radio lock out. I think mainly that was due to poor orientaion of the ariels on my gear.....

Jamie - poor orientation of your aerials - installed by you - is pilot error! The pilot installed them!

John, mate I really think you need to move on from this. Anyone who has been flying for a while will tell you that now and then you get a crash that you just can't find the reason for - its life accept it.

You've done the sensible thing - you've checked anything that you might be doing wrong or that might have gone wrong - and decided it wasn't one of them - so its time to move on. Build your next model. You might fly for twenty years now and it might never happen again.

BEB