I give up!

[winchweight]

Kelvin, it is possible I suppose, but the antenna are usually switched off at the weekends.

Keiran, although unidentified equipment failure is always a possiblity, given my inability to reproduce the fault on the ground, I suspect Scott has hit the nail on the head. I will be changing my UBECs for 6v versions.

[Tim Mackey]

I take it you are being humorous here Scott? If not, then please explain how "lack of voltage" can "send the receiver into failsafe mode as evidenced by the motor firstly shutting off", followed by lack of response to any input controls....which according to both Shaun and his witnesses is exactly the sequence of events in the incident.

Shaun - I did include a fairly lengthy "argument" earlier in this thread as to why I do NOT believe it is a brown out scenario - and I thought you had understood that explanation .... but it seems not - as you are now accepting Scotts diagnosis quote: "I suspect Scott has hit the nail on the head".

[Tim Mackey]

Scotty ! -perhaps you would care to answer the points in detail which I submitted earlier as "argument" against your diagnosis

Incidentally, I have also performed the same tests with an "electric flight setup" as per Shauns model -EG: a seperate 6V UBEC, an opto isolated ESC fed by a 3s battery and 4 servos plugged in and operating from a QC enabled 6100 receiver. The result of creating a brown out by momentarily switching the UBEC off via a switch inline with its feed to the reciver was effectively nothing noticeable at all ! Rapidly switching the UBEC on/off which would in effect be what happened in the event of power drop from the UBEC simply caused the LED to flash on and off but control was not affected AND the motor did NOT wind down unless the power was kept completely off for several seconds. Even then, upon switching power back in, the motor simply re-started and normal flight controls were resumed. Shaun stated, I think - that the model just "shut down" for 8 - 10 seconds and simply glided in with no motor and no control whatsoever. For this to be due to power supply problems would require that the UBEC he was using completely failed permanentley ( which post crash testing confirmed it did not ) or the main flight pack to have come disconnected somehow.

I still say its signal failure
Created a great discussion and "argment" though LOL

[Kelly]

I hope you don't have the same thing happen with you new Fury shaun, whatever the cause?

Hope you are still having fun with your Spitfire.

 I think Jetsome has just entered the"Twilight zone"  .

[BB]

UFO's yeah that sounds about right.  Don't forget your ray-gun next time you visit the patch. And I wouldn't bother with using the 'stun' setting either - That'll learn erm !

[winchweight]

Timbo, having re-read this thread, you are of course right, especeially in conjunction with your video experiments. It seems like such a long time ago now, that it's all becoming a blur.

You did prove conclusively that low volts did not engage failsafe, but signal loss did.

Jetsome has had too many great flying days stood out in that sunshine....

Kelvin, the Spit will fly again this weekend, weather permitting. My confidence in the kit was dented last week so I didn't fly it.

[Tim Mackey]

The only difference between the "servo on throttle" and "ESC on throttle" scenarios is that sustained power loss ( sufficient to cause the rcvr to stop ) will cause the ESC to shut down the motor, whereas there will be no throttle servo auto-movement at all, as failsafe per se will NOT happen.

However sustained power loss is not brown out....more black out! - and your post crash testing shows this to be highly unlikely.

Brown out ( as - ironically - explained properly by Scotty earlier in the thread ) is almost always a case of the supply being very briefly - perhaps nanoseconds only - suppressed enough for the receiver to fail, and this power drop could well be only millivolts - however..... as soon as it does, the power drain which caused this voltage drop EG: motor, servos, the esc, whatever is connected to the rcvr is instantaeously removed, thereby allowing the voltage to increase back up those few millivolts necessary and the rcvr "boots up again" and the cycle repeats very rapidly providing you have QC enabled which you had.

This rapid cycling on/off has no visible effect on the model either servo or ESC throttle equipped. Servos may be a bit slower, or perhaps jitter slightly.... but probably you never even notice. The whole reason that Spekky arranged for the rcvr LED to flash following this occurence is because without it, you would likely never even know it had occured!

If people still doubt this....repeat the experiment I did - with an ESC and UBEC system as I have also done ( film evidence is again availabe for those who would like to see it ) and you will see what I mean.

Your crash description just does not match that of a brown out. You had what seems to me to be the closest thing to a PCM lockout which I suffered on the last 35Mhz model I ever flew a couple of years ago- signal was lost ( and I never found out why ) or interference was happening...and the JR PCM rcvr went into failsafe and I stood watching the model fly itself straight into the ground. The throttle closed off first, and the model dived at the ground. Of course, your'e wondering why I did not have failsafe set to either neutralise sufaces or even apply a little up elevator ( which is possible with PCM but not with the AR6100 /DX7) in the event of failsafe right ?

I did..... unfortunately I was inverted and 6 feet off the deck at the time

[Nick Rigg]

How about "I'm a cr*p pilot"?

[Lee Bentley]

Horizontal stabiliser failed structural integrity during waterfall manouver.

[nasa_steve]

jetsome

   to be honest your polyquest are exactly the same as flightpower cells ,so short of there being some variance between the cells IE older different batch there can't be any difference as both cell assembler's use the same cells.

    of course this can vary if for example your ployquest cells are 20c varients and the flightpower are earlier 15c cells. but whatever you buy at the present time be it flightpower 20c or polyquest 20c or hyperion for that matter they will be the same Enerland cells inside the pack.

nasa

[scott cuppello]

Theories? Kind of, got it from transponder timing systems in motor racing, where you can see a direct relation to signal strength and voltage on screeen, but it's my little theory, that's all.

 We did extensive range testing with 4.8v and on certain Spektrum recievers and had poor range results, on the same recievers since switching to 6v......spot on, never a problem since....good enough for me.....I don't have aircraft fall out of the sky anymore....and neither does anybody I know who has also converted [a lot!].

[Tim Mackey]

Hi Scott -So how do you directly answer the points I made about

1) The hundreds of successful flights I and others have had on simple linear 5V BECs.

2) Your suggestion that "lack of voltage sent the receiver into failsafe mode as evidenced by the motor firstly shutting off" - and me stating that this is impossible - a lack of voltage cannot cause a receiver to go into failsafe as I keep explaining ( and proving )

PS the PSU arrived today thanks - it works fine too

PPS I am off for an early night - catch you lot tomorrow

[winchweight]

Hi guys, sorry i had to turn up at work today and I am just in.

Timbo, I understand now, thank you for your experimentation and explainations.

I guess it's one of those things we write off to experience. On the up side, HH were as good as their word and my new AR6100 was delivered today FOC. So thumbs up for HH.

Other than that I guess we've beaten this to death until the next time!

Thanks for everyones input, cheers!

[scott cuppello]

I can explain the hundreds of people not having a problem....it all comes down to the odd BEC or UBEC giving the wrong voltage, ie; faulty, or and most commonly, over loaded BEC's, this is why failures happen....so...give yourself more headroom and go to 6v.....why people are persisting with 5v is a bit of a mystery to me.

As for the failsafes....sorry matey...you are plain wrong....when I was having failures....first sign was a failsafe that there were problems....and as it happens, my A-7 Corsair, one of the few I have left on BEC with 5v output did exactly that the other day....now, Iv'e flown it loads, but it was the day the other day....the day it decided not to play any more, went failsafe....knew what was coming...so once I had control again, went to bring it in, except it did it lower this time and in it went......believe me....that is an equally familiar story I get from Spektrum users.

 At the end of the day, I can only relay my experiences based on my own models like you guys, but I also having the privelige of talking to hundreds and hundreds of modellers.

[Tim Mackey]

Well Scotty it seems we shall have to agree to disagree. I have tried repeatedly ( and filmed the process ) to get a 6100 receiver to enter failsafe mode by simulating a power drop / cut. It will simply not happen. Sure, as I described, the ESC may well shut the throttle due to sustained power loss but that is not proper failsafe as such - simply a function of most ESCs. Furthermore, a QC enabled 6100 as was Shaun's will hardly be even noticed to glitch let alone shut down and remain "dead" for 8 - 10 seconds.

Perhaps we are at cross purposes here about the meaning of failsafe?

I am discussing receiver failsafe - NOT just the ESC shutting the throttle.

Anyways... I shall continue to experiment with various scenarios, and keep reporting the results in my thread on "brown outs and grey areas"

Cheers mate... as they say...."its good to talk" especially when it can be done in a friendly way

[scott cuppello]

You may be right, throttle shuts for sure, but nothing else responds, but what I'm also convinced of is that brown out/signal loss is one and the same thing.....in other words, range is voltage sensitive.....so we are pretty well agreed really.....sadly, I have had to learn the hard way! And quite honestly, should have "listened" to the manual, and not the internet chat [one of the occasions where internet chat is harmful].

I always urge people buying Spektrum now to read page 102 of the manual, where it states quite clearly to expect signal loss if the RX voltage drops below 4.7v.

Good to talk indeed....this is how a lot of people pick up info!

[Lee Burke]

This a rather confusing post, to me at least, Scott.  I need your help in understanding it, please.    You say you are convinced that brown-outs and signal loss are the same thing?  But surely a brown-out, ie reduced and insufficient voltage to the receiver, can be caused by a number of things, but none of them is signal loss.   If you turn your Tx off, causing signal loss to the receiver, it will not suffer a brown-out as a result, will it?  It remains ready to connect to the signal as soon as this reappears.  On the other hand, a sufficient voltage drop, caused, by whatever reason, will shut down the receiver until such times as the voltage returns.  In this case it does not matter how strong the signal may be at the receiver it will not be able to decode it.  So, as far as I understand it, brown-outs and signal loss are two distinct and separte problems each of which requires its own solution.

It seems these ideas are not at all those you hold?  Perhaps we are somehow talking about differant things? 

[Tim Mackey]

Well Scotty, I hope this does not appear as if I am obsessive about this point, but on a point of detail, I simply can't agree that brown out and signal loss are one and the same thing .

My definition of a brown out is a temporary, sudden, and very brief fall of supply voltage - sufficient to activate the LED flashing but not to close the throttle. This brief voltage depression is commonly caused by overloaded servos or poor regulators or supply packs incapable of maintaining sufficient voltage. It is, in my view the most common example of brown outs, and almost always results in an almost oscillating performance of the receiver, as voltage swings low/high very rapidly ( as can be seen in my videos ) - the nett effect being sluggish or jittery servo movement but ESC throttle commands are unaffected. The only time throttle may be affected is if the radio supply power failure is sufficiently long to cause the ESC to shut down - but this is more what I would call a black out and points to virtually complete failure of the power supply be it BEC / battery / or whatever!

My definition of signal loss is well....signal loss ! / dropout / or interference - in which case the receiver will enter failsafe, the motor will shut off accompanied by freezing of all other receiver outputs...until reception is - hopefully - resumed. Many seconds could elapse whilst the TX finds available frequencies once again. The LEDs on a QC receiver will not flash following this signal loss / failsafe.

As for range being voltage sensitive, that is very interesting, and I must do more testing of this scenario - as if true then the failing range sensitivity could cause true failsafe as a result of signal loss, which is a by product of the low voltage. However I have not found this to be so yet - more tests imminent

part two of my post is below - too long for one posting

[Tim Mackey]

I only have the DX7 manual which came with my set 2 years ago... and it was / is ( by admission from HH themselves  to me in writing following my complaint )  a hashed up version of a 72Mhz version manual - and the section you mention ( from page 102 ) is re-printed below.  It does not say that you can expect signal loss if your RX voltage drops below 4.7V - it merely says you might crash...which indeed you might if that low voltage persists....but not due to signal loss

Note also it mentions "do  not extend the antenna" and later on... " for PCM only "

- what are those items doing in a manual for a pure 2.4Ghz set ??

Daily Flight Checks
1. Check the battery voltage on both the transmitter and the receiver battery packs. Do not fly below 9.0V on
the transmitter or below 4.7V on the receiver. To do so can crash your aircraft.
Note: When you check these batteries, ensure that you have the polarities correct on your
expanded scale voltmeter.
4. Perform a ground range check before each day’s flying session. The range check should be as follows:
• Do not extend the transmitter antenna at this time. Turn the transmitter “on.” ETc Etc
• For PCM Only: With the throttle fail-safe preset to idle, bring the throttle slightly above idle. Walk
away until the throttle drops to idle. This will be the distance of the range check. ETc Etc

If you have a different version of the manual - I would like to see it

All interesting stuff, and I know that in the main, we are agreed on the best way of avoiding brown outs - use an adequate supply - 6V preferably - and of sufficient capacity and ability to deliver that capacity. Its the detail and technical reasons that perhaps we differ on, or indeed just the terminolgy itself

See you at the Nats then with your snazzy blue shirt on again ??

[Kelly]

Has anyone had the same  problem with Futaba? 

It would be interesting to find out if it is a problem only with Spektrum ,or common to all 2.4 sets?

Kelvin. 

[Bravedan]

I had the following setup:-

Flying Wing, 2212-6, 30A ESC, 1800mAh 25C 3S. 5x5 prop, (all supplied setup for ARTF wing), FASST 2.4 via 6EX Tx

30 year plus experience pilot, retired professional electronics/process control engineer (!)

I had an instance where it lost all control at height while flying on about 3/4 throttle, but just regained some control at near ground, just enough to flatten hit and it survived with only a bent motor mount and scraped prop. No reason found, all worked by time I got to it, unable to get it to fail again in tests.

I suspected the ESC had taken the BEC supply off on a temp cutoff, as the supplied ESC was being run nearer max output than I usually set my systems up when on WOT, and was getting quite hot, but no proof.

Flew a few times more tentatively, then increasingly less tentatively until it again while running circuits on WOT cut all control, flipped up and out of cct, fell to earth stone dead all way down despite trying ESC reset several times, and nose crumpled, etc...............again all working by time I got to it.

Range was not significant either time............. battery was WAY above voltage for cut off, in both cases only about a Min into it's flight time.

Repaired airframe (good old EPP!!!) , replaced prop with a 5.25x4.75 which reduced current draw, and replaced ESC with a 40A unit.....................has since had many times of heavy use inc lots of WOTand also light cruising use since with ALL OTHER ORIGINAL COMPONENTS INTACT and untouched.................no further issues.

So, what was it...............??  I suspect the ESC was hitting thermal shutdown temp and then cutting off the supply to the BEC, forcing the Rx to reset................

[scott cuppello]

OOh, splitting hairs a bit I think?! And as I keep saying, go to 6v problem [all of them] over.....and sorry, but the condition you describe as signal loss/fail safe has always preceeded a crash.....caused by brown out. Timbo mate, I also know people who have static tested the brown out voltage, and swear it is 3.5v......problem is, in practice, it happens at way above that voltage....solution is 6v.

[Lee Burke]

As Shaun said in the beginning, I give up  

[Tim Mackey]

Scott Cuppello wrote (see)

OOh, splitting hairs a bit I think?! And as I keep saying, go to 6v problem [all of them] over.....and sorry, but the condition you describe as signal loss/fail safe has always preceeded a crash.....caused by brown out. Timbo mate, I also know people who have static tested the brown out voltage, and swear it is 3.5v......problem is, in practice, it happens at way above that voltage....solution is 6v.

Not splitting hairs at all Scott - which bit are you refering to ? - and I still disagree about those statements above

1) "Go to 6v - problem over ALL OF THEM". 

No way.... merely going to a 6V pack could in fact, in some circumstances make matters worse. Using 6V increases current consumption on a given rig - this means the battery will drain FASTER and this can lull people into a false sense of security - see the editors piece last month in the mag in his heli section! I agree that a 6V BEC/ UBEC is a better option than 5V and have never disagreed with that... but simply saying " go to 6V and all your problems will disappear" is wrong.

2) "Brown out happens at way above 3.5V" - it doesnt, it just doesnt !!

In practice - as you put it, what happens is the voltage source gets low, coupled with perhaps an inability to supply the current quickly enough - due perhaps to using "lightweight" AAA cells or something equally unsuitable, further coupled with low cross section wiring or less than perfect connectors etc and the voltage at the receiver drops to 3.5V or lower for a split second only.... and bingo - brown out has happened, probably triggered by a servo movement, or even blow back against a control surface... but whatever the reason, the voltage was down at 3.5V or very very close. Brown out WILL NOT HAPPEN at figures "way above that ".

I have filmed evidence to back my claims, I have deliberately tried to force a brown out using silly little 3 cell packs and this is the result. Every time.

Sorry mate, until you show me a brown out occuring, with a DVM connected to the receiver displaying more than 3.5V ( or very very close ) I have to believe my tests.

PS have you contacted HH to tell them that they are lying about the receivers ability to perform down to 3.5V - I know they recommend a higher ceiling - as I do - but they do state that they work down to 3.5V, and this IS the subject we are discussing here. Maybe we should end this "conversation" and topic now, and let people make up their own minds about the situation, after all if nothing else is clear cut, it does seem clear that we will never agree on this technical issue - you obviously have your ideas and experiences, and you are completely entitled to them.

PPS I still like you

[scott cuppello]

Well I can tell you is this, my own experience, and the experience of a great many of our customers is that brown out/signal loss....and the point here is that more often than not....you can't tell any difference....the model fails and only takes a second or two to hit the ground....you walk over to it and everything [except the model of course] works.....so, as I said, based on my own experience, and the experience of many of my customers is.....go to 6v...problem stops [which is what I partly meant about splitting hairs...and the bit in the manual, "could" fail at 4.7v is good enough for me not to run a 4.8v input!].

 Give you an example that does not involve a BEC or UBEC, my FW190, first flight fine, 2nd flight [which is where all the problems have occured using 4.8v Nimh RX batteries] and massive brown out....just about recovered it after RX kicked back in....so yes....I'm saying that signal loss [which I don't believe basically exists with Spektrum as I can't see how/why random signal failure would occur] IS brown out.

If you remember, we tested all Spektrum recievers on the ground and were particularly unhappy with the range of the AR6200, now, I'm not going to lob these in the bin, so, stuck them in foamy EDF's....albeit very fast ones....with a 6v supply....and have had no issues with them since?!? So, I can only draw the conclusion I have.

When I spoke to somebody at Horizon, they agreed....for electric models in particular....6v supply from a UBEC is the safest option [they are the first to admit that many leccy fliers have crashed on Spektrum....they, quite rightly, blame the BEC supply].

 Timbo....still like you too.....!