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Why the saddening blow to my fms mustang?

receiver / servo glitch made my p51 nose dive : (

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Peter Miller06/07/2017 11:06:36
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11473 forum posts
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10 articles

I have been using a Spektrum DX7 since they first came out. ONLY failure was when I switched it off in flight.

Our Club secretary lost three models when using a DX8 and another lost two models with one receiver. He binned it and had no trouble since.

Various other members are using Spektrum including a DX8 on Giant scale models. No trouble with them.

LMA Dave06/07/2017 12:02:36
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221 forum posts
75 photos

I have to agree with the post above, I've used Spektrum since day one and never had a radio failure yet, I have had plenty of pilot failure. Maybe I have just been lucky with Spektrum, But then again I must have been lucky with Futarba as well, when they where having issue at the beginning.

There is nothing worse then losing a model on its first flight I hope you fine what caused it.

Kim Taylor06/07/2017 12:30:03
322 forum posts
55 photos

Posted by ted hughes on 06/07/2017 09:38:31:

It is always Spectrum, isn't it?

I wouldn't use Spectrum even if they gave them away.

Okay, you might need to spent an extra £100 on the radio, but at least you could rule out radio problems after a prang.

Edited By ted hughes on 06/07/2017 09:41:39

How can you start by saying that, then follow up with

I'm not saying Spectrum are bad, but at least you could rule the radio out as a suspect if you were not using it.

This is the third thread here at least, that have involved sudden crashes where the radio may be at fault, in the last 12 months (sorry, can't do multiple quotes)

Those two statements are plainly contradictory, and for the record the crash happened in 2011, so a bit outside your 12 month time frame.wink

I use Spektrum, as does probably 80% of the people I fly with regularly. It is probably the system purchased by most newcomers or returners (that'll be me then). That means that there is at least an 80% chance that a failure among my clubmates will be Spektrum. This is not the case for me at least.

Are they perfect - clearly not. But root around below the bias and sensation and I bet you'll find no greater %age of failure than for any other make.

I know that if one of my models crashes, it's MUCH more likely to be finger trouble than radio failure.embarrassed

Kim

gangster06/07/2017 14:58:46
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1049 forum posts
29 photos

Sorry to hear of the loss of your model. I am sure that is one thing that all modellers can empathise with. Never a nice thing to happen to anyone. Clearly you need to get to the bottom of this to prevent a re occurance. Unfortunately unless you have a specific question I don't believe the answer will be found on this or any other forum. The only way to get under it is by a careful and logical testing process together with a logical thought process to analyse the results. Guess work, blaming reasons that cannot be proven (interference has been the universal excuse since time began and to be honest in most cases about as likely as voodoo or evil spirits) it also does not help when those with a predudice against a certain make of radio tell you that it is definitely the reason . I accept that a number of those predudices may be based on a genuine bad experience and who could blame them but many would probably have problems whatever make of radio they use. So test very carefully, and by all means come back on the forum and check with others the validity of the results. No point in guessing and sometimes a second opinion clarify the thinking wishing you good luck it's not a pleasant place to be

Denis Watkins06/07/2017 15:28:31
4649 forum posts
131 photos
Posted by Martin Harris on 15/06/2011 10:26:54:
One possibility that you should consider is that despite the nose down attitude it may have been stalled. I know it appears to be substantially vertically nose down but it's possible that the video is a little deceptive and many models can stall well before 15 degrees AoA.
 
With a rearward C of G (and I agree with most other posters on this being the apparent case) the natural tendency to self recover is lessened and the flight condition before the final impact appeared to be of stalls, recoveries and further stalls - but was fairly far away so this might not be the case.
 
If you had full up elevator applied (a natural reaction) this may very well have allowed the stall to continue as the critical angle of attack may have been exceeded.
 
In total agreement with this statement

kc06/07/2017 17:23:04
6708 forum posts
173 photos

It could be any number of things as everyone said .........however when I read your report the thing I noticed was you said " got the landing gear up and banked round thats when issues were made apparent" and later " thats when it happened landing gear down ready for a nice landing and dow it went again "      Is it a coincidence that the worst problem occurred when the retracts were used?    My view is a possible cause could be the retracts taking all the available current and not allowing the Rx & other servos a chance to work - hence losss of control.  

Something to check in future --can the ESC or nicad supply enough current for several servos all at once.

Edited By kc on 06/07/2017 17:28:37

Dave Hopkin06/07/2017 17:45:22
3672 forum posts
294 photos
Posted by kc on 06/07/2017 17:23:04:

It could be any number of things as everyone said .........however when I read your report the thing I noticed was you said " got the landing gear up and banked round thats when issues were made apparent" and later " thats when it happened landing gear down ready for a nice landing and dow it went again " Is it a coincidence that the worst problem occurred when the retracts were used? My view is a possible cause could be the retracts taking all the available current and not allowing the Rx & other servos a chance to work - hence losss of control.

Something to check in future --can the ESC or nicad supply enough current for several servos all at once.

Edited By kc on 06/07/2017 17:28:37

Are we sure there was no CoG change as the wheels came up?

Peter Christy06/07/2017 18:26:11
1901 forum posts

I notice on the video that the aircraft apparently made three wayward dives before finally going in. I have to say, if that had been me on the box, I would have been throttling back and aiming for a quick landing after the first excursion!

Unfortunately, after such a severe crash, it will be difficult to ascertain exactly what failed. It does look like a loss of elevator control for whatever reason. Had it been a total loss of signal, I would have expected the motor to shut down - most electrics do this, even if the failsafe hasn't been set (was it set?).

This leaves either a servo failure, linkage failure, or possibly a CofG issue. I'm not completely convinced by the CofG arguments, though I wouldn't totally exclude them, but my money would be on a servo fault.

I bought one of the Meessrschmitt Komet ARTFs a while back, and on receipt, one elevon servo would jitter wildly at one specific position. Luckily, I spotted this on the ground when setting up the radio, and replaced both elevon servos.

When checking servos, it isn't enough to bang them from end to end and check direction. Moving the stick slowly and smoothly from one end to the other will often reveal jitter spots that banging the sticks from end to end will simply skip over.

Bear in mind that any jitter spots revealed by this test could just as well be on the transmitter as servo. The only way to tell which is by substituting the servo and see if the fault goes or remains.

After a crash like that I would strongly recommend checking the transmitter as described above, just in case!

--

Pete

Michael Wright06/07/2017 19:26:38
67 forum posts
10 photos

With my experience of bad flap servos and very poor quality links, and the thing I find really telling: the other crashes, on maidens, with video on youtube to back it up all suggesting servo/links failure. I think that is the answer! Too many planes doing the same thing from the same company!

Dane Crosby06/07/2017 21:21:10
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252 forum posts
23 photos

hi, I had a Bixler 2 a couple of years ago. I had the same flight path snags. (Thought it was me...I was a newby at the time) after two or three crashes I found that the ESC was very unreliable and was prone to short term shutdowns when tested on the bench. The Bix had been going in and out of failsafe, confusing my little brain . A new ESC and all was well apart from a very ugly, many times repaired, Bix. RX was an AR6210.

John Davies 406/07/2017 22:45:08
29 forum posts
1 photos

I know this is an old post , but back in the early 90`s I had a brand new Futaba FF7 , the early version with no model memory , anyway it was in a TopFlite P40 Warhawk , with a brand new Enya 60 , infact everything was brand new . It took off no probs , I did a circuit and next thing it rolled inverted , I rolled it upright , and a few seconds later it rolled inverted again and ploughed into concrete hard ground , totally smashing everything , engine included In fact I have never seen an engine so badly smashed , it was literally in pieces , even the crankcase was smashed . To say I was a little p****d off would be a massive understatement . I duly returned the radio gear to the local H/S where I bought the radio and they duly sent it off to Ripmax . After a considerable wait it was returned repaired free of charge , the fault having been traced to a dry joint on the SMT pcb in the receiver . On enquiring about the total loss of the engine and airframe plus all the other materials used to build the kit the shop owner shook his head and explained that there was a "get out clause" in the small print stating that they Futaba would not be held responsible for any other damage or loss They should I think be responsible for damage proved to be caused by their faulty product .

Piers Bowlan09/07/2017 14:22:31
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2172 forum posts
53 photos

I am no expert on retail law in the UK, perhaps someone else on the forum is. Futaba are entitled to write what they like in the small print but there is no such thing as a 'get out clause'. Products must be of merchantable quality and fit for purpose. Your faulty receiver was repaired fair enough but I would have thought the model shop would have incurred some liability for your financial loss as a consequence of the model's crash and total destruction. If you had a written report from the Ripmax service centre to prove it was faulty you might have had some leverage with the model shop. I suppose you might have some difficulty in proving that it was that receiver they sold you.

If for example you buy a car from a dealer and after you drive down the road the brakes fail causing you to crash, your argument would be with the dealer not the manufacturer of the car. If you were forced to sue to get compensation you would sue the dealer. The dealer would then have to try and get redress from the manufacturer. Liability is always at the point of sale.

I don't think it would have been unreasonable in your case to politely request the model shop to go some way towards compensating you for your loss by, for example, supplying a replacement model and engine at cost. If his response was mirth and incredulity you could have then written to him saying you will in that case pursue compensation in full through the small claims court. He might then take you up on your original offer!

This is all historical and now academic of course. However, I wonder how many of us have lost a model due to a product failure and for us to simply shrug and consider it to be just 'one of those things' or 'something that happens' with model flying . I know I have.

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