Fail Safe setting

[tigerman]

I have Futaba radio systems on all my models and have check that if I do not get a signal from the transmitter the fail safe cut in a shuts the throttle down etc,that is fine all my model do last week I flying a model when I lost control of all the controls, I could not shut the throttle down ,the ailerons did not respond or any other control .It was obvious that I had lost power to the servos which is either Transmitter signal, switch failing or a duff connection from the battery.I have since ruled out the transmitter and switch so it is down to a duff battery.My point one of our club members said did you have the fail safe set in the receiver so if you lose power from the receiver battery the throttle would shut down.I know you can set the fail safe in the transmitter but never been told you can set the receiver to shut down if you lose power from the receiver battery.Is this correct or are they winding me up?I have a 617 receiver in this model

[The Wright Stuff]

I don't know which specific Futaba system you are using, but normally a fail safe guards against loss of signal, not loss of power.

If it's an electric model (you don't say) then the job of the low voltage detection usually is within the ESC, not the receiver itself.

In an IC model, if the receiver battery fails, there is no power to move the throttle servo.

[Alan Gorham_]

You set the receiver battery failsafe via the transmitter, but in some cases it defaults to the throttle channel only anyway and reduces throttle by itself to warn you to land ASAP.

It is covered (admittedly not very clearly) on page 60 of the Futaba 8FG manual.

[Former Member]

[This posting has been removed]

[Alan Gorham_]

Futaba's battery failsafe only works under certain pre-conditions and that is that the battery voltage is dropping but not collapsing and that a 4 cell battery is used.

So it would probably warn you of a battery pack in good condition that is just going flat, but would not help with a faulty battery (dead cell or faulty connection).

You decide how useful that feature is, I am only passing on my understanding of the feature as a Futaba user.

[Dwain Dibley.]

Posted by Percy Verance on 03/05/2017 16:15:49:

If power is lost to the receiver and there is no back-up supply, I don't see how the fail safe can activate.

D.D.

[Chris Walby]

I think the intension is for loss of signal not loss of RX battery.

I would also suggest that the RX will suffer loss of signal prior to loss of control of the servos, so the last thing it will do is drive the servos to failsafe position.

What happens if the throttle servo fails....same as RX battery failure, unlikely but without a backup system most of the TX, RX and servos are all single points of failure

[Denis Watkins]

Just bind your receiver with the throttle stick down tigerman

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[Engine Doctor]

If the recover loses power nothing works, simple . The fail safe is designed to operate if the signal from the tx is lost.

[ChrisB]

Yep, if there's no power to the receiver then it can't go to failsafe,simple as that.

The only way to get around that is to run two batteries and two switches which is reasonable for models over 7kg, which is the way I do it.

[tigerman]

So basically I was right if you lose power to the receiver due to a faulty battery or what ever that is it .I thought that was right ,I fine with that and can live with it just thought there was something I did not know .Luckily the model went into a slow turn and crash in our flying field with no damage to anyone but a totally destroyed model.I was lucky because there was no damage to the engine our radio gear and I have put the radio gear back in a cheap foamy and use the same transmitter with a new receiver battery and everything seemed fine ,had several flight and not so much has a clitch.Finger crossed it was the battery

[gangster]

For peace of mind I would also change the receiver switch harmess. They are cheap nasty things and capable of going intermittent or high resistance and susceptible to corrosion. The same is true of the transmitter switch although it sounds like you can rule that out in this case as the failsafe would have done its thing

[Don Fry]

Tigerman, have you checked the battery. If mine I would do a bit of checking rather than assume you have nailed the problem.

[tigerman]

The battery was total destroyed in the crash and was about 4 feet from the remains of the model ,so it is hard to check if the battery was working .I have replace the switch and fitted a brand new battery and put it all in a cheap little foamy to test it all I am still using the same receiver and so far ,fingers crossed I have had several flight now and all seems fine but I will keep the radio gear in the little foamy for a few more flights to make sure all is OK

[Solly]

Posted by gangster on 04/05/2017 06:44:35:

For peace of mind I would also change the receiver switch harmess. They are cheap nasty things and capable of going intermittent or high resistance and susceptible to corrosion. The same is true of the transmitter switch although it sounds like you can rule that out in this case as the failsafe would have done its thing

Good advice. I've had TWO switches fail so far this year, fortunately one on the bench and one just before take off. And one of them was bought in January.