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Why the saddening blow to my fms mustang?


matthew carr
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On thursday the 2nd of june I decided to take my big fms mustang for its maiden flight using a spektrum dx6i and a ar500 receiver , lets see it was about 8:30 in the evening sun shinning and a gentle breeze throttled her up and off she leaving the ground nicely got the landing gear up and banked round thats when issues were made apparent it appeared that there was an issue either with the servo or receiver because suddenly the plane would start to descend into a nose dive and it took quite a few wiggles down on my elevator stick to get her back up as the plane was not responding to the controls given this happened 3 times then I said to my other half I have go to bring it down because something is seriously wrong and thats when it happened landing gear down ready for a nice landing and dow it went again this time straight into the ground as you can all imagine i was mighty annoyed and a tear almost came to my eye a brand new plane compleately rit off i was horrified , anyway took what was left of it down to my local rc shop and they told me it was the receiver so i phoned spektrum/horizon to see what they could do for me and what i got back was " we can replace the receiver for you " i thought to myself just a receiver is no good because i cant fly a receiver , and still now I have no idea on what to do about this , any help or advice would be great and i will see if i can get the video of the whole 2min7secs of flying gltching and crashing on here , Matty
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How did the model shop come to such a quick conclusion that it was the receiver?
What actual testing did they do - did they use the receiver with another Tx?
How can they be sure the Rx was not damaged in the crash etc?
Sorry about your model

Edited By Tim Mackey - Administrator on 09/06/2011 09:07:01

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yes done all my range checks and everything appeared to be fine with throttle on an off i just cant work it out and it has majorly wound me up , the model shop came to that conclusion from watching the video as well , who knows all i know is it looks like i will have to falk out for a new one
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Excuse my bluntness - but the model shop can NOT diagnose that the fault was with the receiver just by watching a video - and this to me, shows a lack of understanding and indeed professionalism on their part. Im not saying that it definitely isnt the rx, but I am definately saying that there is no real proof yet that it was!
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Commiserations about the model - they are a bit desirable
 
What is your level of experience, Matthew? Without a few words in your profile, it's difficult to get an idea of where to start. I agree with Timbo that the model shop's diagnosis seems very simplistic.
 
It could be a receiver fault, or a power supply problem, plug wiggling out of the Rx, control link coming adrift, C of G in wrong place, too much elevator throw, or just plain old-fashioned finger trouble (it happens to us all!).
 
Can you recall if the Rx light was steady on, flashing or off when you reached the scene of the accident? Any sign of broken linkages (which may be pre- or post-incident?). Were all the plugs and connections secure?
 
As you'll appreciate, the more info you can provide, the better chance we'll have of getting to the bottom of the problem.
 
Pete
 
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Matthew.
Sorry to hear about the crash,but Tim and Pete are spot on there could be many reasons why this happened.
Do post more details ,and a profile would also help ,all the possibilities need to be investigated.
The first take does point to control difficulties when the retracts were operated.
 

Edited By Tom Wright 2 on 09/06/2011 12:49:00

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Sorry to hear about your crash Matt. Very sad.
 
In my experience when a new model goes in on its maiden flight it very rarely radio reception problems. It does happen but, in my opinion, its not the most common reason for crashes on maidens.
 
More likely is a "build fault" of some kind, and that could be almost anything;
 
rx power supply via the ESC throttle cable - the cable has a faulty joint, partially broken wire, plug not properly pushed home.
 
control rods- clevis coming loose because it wasn't fully locked on, control rod binding or snagging, loose rod connection to the servo.
 
the servos - new servo with intermittant fault, intermittant power to servo because of damaged wire or plug not pushed home.
 
Control surfaces - binding, hinges not glued properly.
 
The list goes on...you get the idea. Some fault of this nature, related to the build, is more likley the problem - especially if the Rx has been used before in another model and is known to function OK.
 
As to which it is - well Tim's spot on the money - only a detailed examination of the wreakage might reveal that, and to be honest even then you may be none the wiser - if a plug is disconnected that could be the cause - but it might also have happened in the impact.
 
The long and short is a totally agree with Tim - the model shop can not just look at a video and then dismiss this as Rx failure. It ain't that simple!
 
BEB
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well i have been flying rc planes for the last 2 years and i have got a wot 4 foam e , st model blaze , art tech jetiger and a graupner gf-15 also started to fly helis as i have got a blade 120sr so you could say i have a little bit of experience i hope this helps you all knowing a little more about me .
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my gut feeling is either receiver or servo plus apparently there have been some issues with some of the spektrum ar500 receivers , and it was strange because at times it was ok turning and other times i would start to bank round and thats when it would start to go down but 3 times i managed to pull out of the nose dive because one minute the elevator would not respond hence the nose dive and the next it would kick back in and up i go again . Matty
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I promise I won't laugh, Matty() - we've all been there and walked the walk.........
 
Whilst I'm not pre-empting the post-mortem, it's interesting that an AR500 is involved. I've used Spekky gear for 3 years+ now and the only Rx I ever suspected may have been the cause of a crash was an AR500 in my E-Flite P-38. Twice it dived into the ground but, with my lesser experience at the time, I was reluctant to claim anything other than pilot error or elevator flutter but, nevertheless, the suspicion was there.
 
I have used it since in another model without problems but it is now in the spares box - I'm using the Orange Rx's more and more now.
 
Pete
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It could also have been a lack of signal - faulty or damaged aerial on either Tx or Rx - how was the Rx installed - was the secondary extension aerial positioned well away from the case mounted aerial? How do you hold your Tx? Is the aerial angled etc etc.
I have around a dozen of the AR500s and have never had an issue with them.
I have however ( as most peeps ) had a crash or two that was just never explained - its sad, but its a fact, these things happen, and its darn annoying - I know !
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the tx aerial was positioned diagonally and the rx was installed very well with double sided velcro tape to hold it in position as for both aerial wires they were both located well so nothing to interfear with them , i should be able to get the video on for tuesday/wednesday as me and the other half are having our broadband fitted
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Well I stick by my original comment - impossible to blame the receiver - in fact I dont believe its possible to make such a surefire diagnosis from simply watching a video of ANY crash. Apart from a very steep climb out, which initially made me think she was tail heavy, the rest of the flight seemed pretty "normal". I notice the trouble only seemed to occur as you were flying at a distance, which does sort of suggest a reception / signal issue, but as I say.....not possible to be certain. I would have liked to see the model flown slower at some point in the flight - to ascertain its slow speed handling and perhaps help convince me that the COG and control throws etc were all good.
Again... tough luck there mate - but it happens to all of us at some point.
How did you get on with the testing /fault elimination procedure I suggested earlier?
Oh,and you might want to check this out too

Edited By Tim Mackey - Administrator on 14/06/2011 23:21:57

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