Topic: Radio problem claimed my Wot4!!

The old Wot4 went in really hard the other day. Has a Frsky V8FR onboard running off a4.8v NiMH pack, both the Rx, pack, and the FrSky V8FT I have in my now ancient Futaba FF8 Tx are less than 6 months old.

Range checked fine, preflighted fine. Took off, climbing right turn to join the circuit downwind and it stopped responding. Got it back briefly then it stopped again for good...

Suspected dead flight pack, and when I got the voltspy on it, it came up good (but not excellent), but dropped into the red if I waggled the sticks to load it up.

Couldn't find anything else wrong:-(.

1) should I be running on 6v not 4.8?
2) does a pack that drops under load indicate a problem in your experienced opinions?

Any other thoughts?

Thankyou.

Ed

The old Wot4 went in really hard the other day. Has a Frsky V8FR onboard running off a4.8v NiMH pack, both the Rx, pack, and the FrSky V8FT I have in my now ancient Futaba FF8 Tx are less than 6 months old.

Range checked fine, preflighted fine. Took off, climbing right turn to join the circuit downwind and it stopped responding. Got it back briefly then it stopped again for good...

Suspected dead flight pack, and when I got the voltspy on it, it came up good (but not excellent), but dropped into the red if I waggled the sticks to load it up.

Couldn't find anything else wrong:-(.

1) should I be running on 6v not 4.8?
2) does a pack that drops under load indicate a problem in your experienced opinions?

Any other thoughts?

Thankyou.

Ed

sounds like a dead cell in your flight pack- either that or it is far too small for the servos (unlikely unless you are using digitals) I assume it was fully charged pre flying?

Had you pushed and held the range check button on the Tx module in error? I laid my Tx against the wing leadind edge, accidently depressed the button and launched a model in range check mode. I cut it flush with the casing to avoid a repetition.

The Rx is meant to work fine down to 3.2 Volts and I use 4 cell packs with all of mine.

Are your Rx antennas installed as recomended?

3001s and 148s. I can't say the pack was 101% full, but it had been well charged since its last outing and had had a topup that morning.

So does the V8FT toggle into range check mode when the button is pressed, requiring ANOTHER button press to exit range check mode, or does it default back to full range as soon as the button is released!?!?!

Gonna feel bloody daft if it's the former!

AFAIK it does need a second button press to exit range check mode and this seems to confirm that http://www.himodel.com/en/info/manual/Manual_2.4G_V8_series.pdf

I always cycle TX power after range checking to be confident it is no longer in range check mode.

Richard

You have to press it again to turn the green light back to red. Or switch the tx off and back on. It definately does not default back to full range on just releasing the button. It has to be depressed for 3 or 4 seconds to go into range check mode.

In my case it was not depressed by my finger but by leaning the Tx against the LE of my wing.That's why I and many others cut it flush withe the module housing.

I always cycle TX power after range checking to be confident it is no longer in range check mode.

Richard

Same here. Its always the best thing to do. I have seen others make this mistake.

Si

Suspected dead flight pack, and when I got the voltspy on it, it came up good (but not excellent), but dropped into the red if I waggled the sticks to load it up.

Ed

That'll be it then.

 

My swearbox overfloweth.

I guess the Pack is a secondary cause, but I suspect that I was flying with it in Range Check mode.............................

Schoooooooooooolboy error & "Stupid boy, Pike" etcetcetc.

Not sure about the range issue but I have a guess about the battery. Are you using a high capacity nihm pack that is AA cells?

Check each cell in the battery with a voltmeter. If any are markedly different to the others discharge each cell individually to about 1V (actually you can probably take them a lot lower than that individually) then slow charge the pack at 0.1C for 14 hours or so.

If any cell is still markedly different replace the pack.

Richard

I ask this question in every case like this- did the failsafe cut in?

Didnt stay airborne long enough for it to be obvious whether or not failsafe had cut in. Hmmm, didnt hear the engine go to idle though? To be honest it wasnt a straight cutoff in control, I got it back for the briefest of moments but then it went again. Who knows!

I've bought a 6V pack for the Black Horse Piper Cub (72" span ARTF) I've replaced the Wot4 with. Trouble is my trickle charger only does 4.8v, so I'll have to use one of the auto chargers on it. No great shakes though.

Thankyou for your input folks - I have learned from this.

I've bought a 6V pack for the Black Horse Piper Cub (72" span ARTF) I've replaced the Wot4 with.

If its the same AA cells as I suspect the pack you mentioned originally was I'd still be very wary. Going to 6v is not the solution if the cells drop voltage under load. Getting better cells that can deliver enough current is. By increasing the voltage of the pack you will increase the maximum current the system will take which would make the voltage percentage drop worse.

You need to be sure the voltage does not significantly drop under the maximum load. On a normal checker with about 10 LED's I would not expect to see the pack go down more than one LED when moving all sticks simultaneously.

Yeh it was just a boggo ripmax pack with AA cells in. Are these known to be bad?!? Always used em in the past?

The old Wot4 went in really hard the other day. Has a Frsky V8FR onboard running off a4.8v NiMH pack, both the Rx, pack, and the FrSky V8FT I have in my now ancient Futaba FF8 Tx are less than 6 months old.

Range checked fine, preflighted fine. Took off, climbing right turn to join the circuit downwind and it stopped responding. Got it back briefly then it stopped again for good...

Suspected dead flight pack, and when I got the voltspy on it, it came up good (but not excellent), but dropped into the red if I waggled the sticks to load it up.

Couldn't find anything else wrong:-(.

1) should I be running on 6v not 4.8?
2) does a pack that drops under load indicate a problem in your experienced opinions?

Any other thoughts?

Thankyou.

Ed

By the fact you did momentery regain control i would say you were definately in range check mode, i have deliberately simulated this scenario and the air range is barely a 100 yards with control briefly regained dependant on which way you point your transmitter aeriel then goes alltogether, a quick switch off and back on of the transmitter instantly restored control, i have seen a couple of models fall foul of this problem and god knows how many models worldwide must have fallen foul to it, the answer really is go over to the telemetry version even if your not into telemetry but just for the audiable warning your transmitter gives when in range check mode, well worth the extra few quid for the piece of mind but remember even though the telemetry module can also work with one way receivers you will only get the range check warning beeps when used with two way receivers.

Wouldn't it have gone to fail-safe if it was in range check mode?   Sounds much more like a dead pack, if it can't even cope with waggling the sticks without flight loads.

Wouldn't it have gone to fail-safe if it was in range check mode?   Sounds much more like a dead pack, if it can't even cope with waggling the sticks without flight loads.

It would go to fail safe on loss of signal if fail safe was set up. The thread doesn't say if fail safe was set, in which case the controls would sit at their 'last command position' and not go to fail safe. It would have done nothing if there was no power.

It would go to fail safe on loss of signal if fail safe was set up. The thread doesn't say if fail safe was set, in which case the controls would sit at their 'last command position' and not go to fail safe. It would have done nothing if there was no power.

I was assuming from the later comments that fail safe was set, at least to reduce power,  based on the original poster's comment ...

Didnt stay airborne long enough for it to be obvious whether or not failsafe had cut in. Hmmm, didnt hear the engine go to idle though? ...

Given the absence of fail-safe kicking in, and a known power supply (low voltage alarm when moving controls), I think power problems are a more likely cause than radio failure or range-check mode.   A lot of people raise issues with that range-check function, but you have to try pretty hard to switch it on by mistake, so not the most likely I wouldn't think.

   A lot of people raise issues with that range-check function, but you have to try pretty hard to switch it on by mistake, so not the most likely I wouldn't think.

I thought he said back at the beginning of the thread he had range checked and had not returned the radio to normal range before flying!

See posts 4 & 9.

I thought he said back at the beginning of the thread he had range checked and had not returned the radio to normal range before flying!

So why no fail-safe?  And what about the failing power supply. 

So why no fail-safe?  And what about the failing power supply.

The way the failsafe works is that it doesn't kick in straight away, basically if the Rx doesn't get a correct packet of information it holds the servos, if it doesn't get any good data over a few packets (frames) it goes to failsafe (only if you set it at the Rx though). The Frsky though is very quick to reacquire the signal, so if you are just out of range then the Rx will keep requiring the signal so it may look like intermittent control.

Does anyone else find this such a satisfying thread title? 

CM

Does anyone else find this such a satisfying thread title? 

CM

I don't like the title a all. It suggests the radio was to blame and if you read the whole thread 'operator error' seems to be to blame or perhaps a battery problem!

I don't like the title a all. It suggests the radio was to blame and if you read the whole thread 'operator error' seems to be to blame or perhaps a battery problem!

I think you missed Docs' point.................... it's one Wot 4 less 

Ah, I certainly did....

There is one manufacturer/supplier in the States eningeering staff states that categorically says you must use at a 6 volt battery receiver pack.  Brown outs/drop outs will occur if the overall voltage drops below cut off voltage for the receiver.  When the receiver drops out you can forget about "fail safe."  Fail Safe occurs with signal interruption and thus to some extent relies on the receiver not detecting an incoming signal.  A dead receiver can not detect the absence of a signal. Even a fail safe system requires continued power to go to the fail safe position as driven by the internal receiver circuitry. 

Not only should you use a 6 volt battery pack but make sure it has a healthy rating which keeps current spikes from driving down the battery voltage.  With a typical receiver and four servo system I would not use less than a 2000MAH rated battery.

There is one manufacturer/supplier in the States eningeering staff states that categorically says you must use at a 6 volt battery receiver pack.  Brown outs/drop outs will occur if the overall voltage drops below cut off voltage for the receiver.  When the receiver drops out you can forget about "fail safe."  Fail Safe occurs with signal interruption and thus to some extent relies on the receiver not detecting an incoming signal.  A dead receiver can not detect the absence of a signal. Even a fail safe system requires continued power to go to the fail safe position as driven by the internal receiver circuitry. 

Not only should you use a 6 volt battery pack but make sure it has a healthy rating which keeps current spikes from driving down the battery voltage.  With a typical receiver and four servo system I would not use less than a 2000MAH rated battery.

Mmmm, I think that supplier may be on shaky ground - the voltage range for this RX is 4.8 to 6V. A 6v pack can quite easily reach much more than 6V when fully charged. Each of the 5 cells in a 6V pack can reach up to 1.78V so the 6V pack could be 8.9V when fresh off the charge. Even a 4-cell pack could be over 7.12V but the additional 1.78V could be enough to fry the RX.

Unless using the HV RX version I'd probably stick to a 4-cell pack - but a large one as you suggest.

Richard

There is one manufacturer/supplier in the States eningeering staff states that categorically says you must use at a 6 volt battery receiver pack.  Brown outs/drop outs will occur if the overall voltage drops below cut off voltage for the receiver.  When the receiver drops out you can forget about "fail safe."  Fail Safe occurs with signal interruption and thus to some extent relies on the receiver not detecting an incoming signal.  A dead receiver can not detect the absence of a signal. Even a fail safe system requires continued power to go to the fail safe position as driven by the internal receiver circuitry. 

Not only should you use a 6 volt battery pack but make sure it has a healthy rating which keeps current spikes from driving down the battery voltage.  With a typical receiver and four servo system I would not use less than a 2000MAH rated battery.

So they are claiming that their equipment isn't compatible with many servos including high end ones  there are plenty of servos that are only for 4.8v use.

when I tested a V8FR a couple of years ago, it didn't 'brown out' until the input voltage got below 3.1v, at which point the Futaba servos were giving up the ghost.   At that sort voltage the receiver could still be responding but the servos would be unable to follow commands.  if your battery gets that low it's furked.

when I tested a V8FR a couple of years ago, it didn't 'brown out' until the input voltage got below 3.1v, at which point the Futaba servos were giving up the ghost.   At that sort voltage the receiver could still be responding but the servos would be unable to follow commands.  if your battery gets that low it's furked.

Found the same with Futaba.
I have been flying FASST with Jets, Heli's, props and electricsince it came out.
Only ever use a 4.8 v pack, never had a  single issue.

Paul G.

Sounds very much like the same battery problem that killed my MX2 a couple of weeks ago. Total loss of control at short range (50 metres max) after flying fine for 2 minutes. Battery check was fine for the first flight, this was the second and last one !  The battery was undamaged and had charged up ok but when checked after the crash was virtually flat. Recharged at home which only took 15 minutes or so which didn't seem right. Then left on the battery checker under load. 7 minutes later the voltage dropped off to nothing. Stripping the battery pack down one link basically just fell off so I presume this was a high resistance joint and had been there when manufactured. Just one of those things and very rare but very annoying!

Hey, what's with all the Wot-hating?!

I've got another Wot4 mk3 now (kit, I don't really like ARTFs), an Acrowot, a phase 6, they are the best flying models I've got  and at some point I might fancy a Wotswot.

Really, I'm mystified as to why some folks don't like 'em. In the 15 years I've been at this lark, no-one has ever slagged the Wot4 until this thread!

There is one manufacturer/supplier in the States eningeering staff states that categorically says you must use at a 6 volt battery receiver pack.  Brown outs/drop outs will occur if the overall voltage drops below cut off voltage for the receiver.  When the receiver drops out you can forget about "fail safe."  Fail Safe occurs with signal interruption and thus to some extent relies on the receiver not detecting an incoming signal.  A dead receiver can not detect the absence of a signal. Even a fail safe system requires continued power to go to the fail safe position as driven by the internal receiver circuitry. 

Not only should you use a 6 volt battery pack but make sure it has a healthy rating which keeps current spikes from driving down the battery voltage.  With a typical receiver and four servo system I would not use less than a 2000MAH rated battery.

Whats going on? My old Wot4 (circa 1995) had 4 servos, a PPM rx and a 700mah nicad pack. It flew every weekend for 5 years without a hitch. Was 2.4 invented by battery manufacturers? 

There is higher performance to be had with powerful digital servos and 2.4 radio. A better battery is needed to support that.

The 600mAH nicad, 4 3001 0r 148 servos on 35 meg is s fine combo for a Wot 4. Stick four 10kg+ fast digital servos in and you may well run into problems. Nicads do hold up well under load and you would probably still be OK. Stick a 2600 etc AA nimh in the mix and you may now be in trouble! Add a sensitive old DSM2 rx (or PCM....) and you are likely to have serious trouble.

I like WOT4s. They are very versatile, tough and forgiving. I only have one now (a Megawot) and fly it regularly. However, there are better aerobatic machines out there. Also better gliders and better toasters 

I built and initially set up an EP fixed wing model with a 35MHz Rx, worked perfectly on the bench.

I then swapped in a 2.4GHz Rx, and it was rebooting sometimes as the throttle was closed (on the bench)

Swapped back to a different 35MHz Rx, perfect again.

Then I understood  ................... some time back that new ESC had been briefly on a 500 Heli (test only, unflown).  Under test it rebooted sometimes when the throttle was closed, so was put aside, yes that was on 2.4. 

Repeated the swaps again.............worked perfectly as far as you could tell on 35, rebooting sometimes on 2.4 (the by long experience very robust FASST).

Ergo, on closing the throttle I presume the BEC was dipping its supply below the reboot level..............and the 35Rx was either working through it or the dip was not long enough to actually produce a visible result.

BECs are another kettle of fish!

If it says "3A BEC" don't use it. If it says "5A BEC" don't believe it and use it with caution. If it says "8/15A BEC" then fill your boots.

If it says "2300mAH LIFE" on it, then also get you booties filled.

Switch mode BECS are fine and don't believe the sales pitch about linear BECS being smoother. That is unless you still listen to vinyl and think CAT5 cable is better than 79 strand for speakers