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Why the saddening blow to my fms mustang?

receiver / servo glitch made my p51 nose dive : (

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matthew carr09/06/2011 08:19:36
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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
GONZO09/06/2011 08:34:41
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Did you do a range check, with motor off and then with motor on, before flying???
Tim Mackey09/06/2011 09:06:04
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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

matthew carr09/06/2011 09:30:58
18 forum posts
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
Tim Mackey09/06/2011 10:01:02
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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!
Tim Mackey09/06/2011 10:03:16
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What is needed here, is to connect up the receiver to a supply, and servos. Then do some ground range checks and see how it behaves. Then do the same again with another receiver - changing NOTHING else - and compare.
matthew carr09/06/2011 11:26:45
18 forum posts
hmmm seems like a plan as o have got a few more receivers i will give it a go , any ideas on what you think it could be ? thanks
Pete B - Moderator09/06/2011 12:30:30
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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
 
Martin Harris09/06/2011 12:40:12
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The video might be helpful - any luck posting it yet?
Tom Wright 209/06/2011 12:45:22
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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

Biggles' Elder Brother - Moderator09/06/2011 12:45:52
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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
matthew carr09/06/2011 13:31:07
18 forum posts
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 .
Pete B - Moderator09/06/2011 13:42:14
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That's a good start - at least we know we're not dealing with a novice flyer, mc! Once we've seen the video, we can chew the fat over the possible causes........what's your gut feeling about it?
 
Pete
matthew carr09/06/2011 13:49:53
18 forum posts
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
matthew carr09/06/2011 13:58:19
18 forum posts
i will get the video on as soon as i can for you all to see and no laughing at my facial expression after the crash .
Tom Wright 209/06/2011 14:15:10
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Hmm that sort of behavior can occur if the the C/G is a bit to far back.or the model is flown to slowly.
matthew carr09/06/2011 14:22:33
18 forum posts
well the c/g was double checked before take off and when taking a wide turn it was almost full throttle .
Pete B - Moderator09/06/2011 15:01:24
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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
Tom Wright 209/06/2011 15:40:46
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Posted by matthew carr on 09/06/2011 14:22:33:
well the c/g was double checked before take off and when taking a wide turn it was almost full throttle .

OK Mattew that's good to hear .....must admit the only problems i have ever had on 2.4 has involved Spektrum gear.

Tim Mackey09/06/2011 19:04:59
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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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