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HomeAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › Failsafe scenario when receiver dies
04-03-2018 07:33 AM  3 months agoPost 1
Antsis

rrApprentice

Melbourne, Victoria, Australia

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Hi Guys

We recently had two flyaways where the receiver apparently failed, but kept power to the gyro and ESC. All the models are set to go to idle in the event of loss of signal from the Tx, but would this still apply if the receiving part of a receiver stopped working? One model used Futaba and the other Spektrum.

Ant

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04-03-2018 03:43 PM  3 months agoPost 2
JuanRodriguez

rrProfessor

The Villages, Florida

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Antsis
We recently had two flyaways where the receiver apparently failed, but kept power to the gyro and ESC.
Loss of signal means just that..... that the receiver is no longer receiving a valid signal from the transmitter for whatever reason....

"Failsafe" is a function of the receiver (not the transmitter) and the settings you (supposedly) set are saved in the receiver..... so, if there is sustained signal loss, the receiver detects it and sends the "failsafe" signals to the servos and then they are driven to their predetermined positions you had previously set as "failsafes settings"....

After setting up your "failsafes" and prior to flight, did test them so make sure the servos were driven to their predetermined failsafe positions ??

Given your description that the receiver itself did not actually fail leads me to think that your failsafe settings were probably not set up properly or at all.....

Been there, done that and old enough to know better.....

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04-03-2018 04:01 PM  3 months agoPost 3
Pistol Pete

rrProfessor

Seffner, FL

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Breaking it down with provided info and added LOTS of questions.
Given...unpowered digital servos go limp while powered servos with no signal retain their position. Since it's a flyaway, there had to be power, as you mentioned.

We know that failsafe engages due to loss of signal and can be either set to HOLD last good signal position or pre assigned positions such as centering all servos. (Except throtle)

LOCKOUT, on the other hand, retains last know position and unlike lost of signal, this is due to loss packets, signal saturation, damaged antennas and or positioning. (Carbon frames?)

Since it was 2 helis with different signal protocols, I will assume both are 2.4Ghz and incidents happened in same location. So, I'm leaning to a lockout.

Was the failsafe tested with blades off and turning Tx off at bench?

Were range test done?

Were both helis set up by same person?

Was it a busy day at field?

Which Spektrum protocol, DSMX or DSM2? If used, satellites same protocol?

We can definitely rule out a brownout. However, we need to find a common denominator.

Do the helis share ANY same equipment? Be it Rx battery, BEC, ESC, Switch (high impedance), Servos and or FBL.

When you bind a Spektrum Rx, by default it will use present stick positions for its failsafe. Thus throtle has to be at whatever position where idle rpm is needed for glow or off for electric. No clue on Futaba.

Were the helis recovered?

Was there a blinking light on Spektrum Rx? (if still powered, denotes lost of signal)

ESC such as castle creations also uses a blinking LED for error codes.

Yes, LOTS of questions.

~~Enjoying the hobby one flight at a time~~

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04-03-2018 06:18 PM  3 months agoPost 4
ticedoff8

rrKey Veteran

Morgan Hill, CA. USA

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Given...unpowered digital servos go limp while powered servos with no signal retain their position. Since it's a flyaway, there had to be power, as you mentioned.
Yes - the digital servos go "limp" with no power (or no input signal), but that does not mean there is no "fly away".
I ejected the flight battery on my old GMP Cobra and it kept flying for about 2 minutes (it seemed like 2 hours) while it circled around drifting with the breeze - towards the condo complex about 1 mile away.
Finally, it tipped over and crashed.
Then beat itself to death because the motor was still running.
If I'd had a throttle return spring, the motor would have rolled back to idle and it would have crashed sooner (and safer).

That was nitro and not electric - I assume this post relates to eHeli

In your cases, the motors went to idle.
This is the typical response when the receiver looses the transmitter's signal.
This is typically set when the receiver is "bind'ed" to the transmitter.
And when you do your binding, the throttle is channel is typically "low".

The exception is if the receiver / transmitter is "bind'ed" and the throttle channel is accidentally "reversed" when you did the binding.
Later, while setting the rest of the heli up on the bench, you discover this and reverse the throttle. But without rebinding.
If you have a loss of signal, the receivers goes to 100% throttle instead of 0%.

The question posed was:
...but would this still apply if the receiving part of a receiver stopped working?
My answer is "Yes".

If the "receiver section" dies, that is the same as a loss the signal from the transmitter.

If the whole receiver dies, all the servo's input signals go flat.
Most modern ECS would stop the motor at that point - a flat signal on its throttle input would force to go into shutdown mode.
The servos may also go limp due to their input being a flat line too.
Then, it crashes within the confines of the flying field instead of the houses across the fence-line of the field.

Believe 1/2 of what you see and none of what you hear.
Fake News will be the downfall of our Republic!

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04-03-2018 07:22 PM  3 months agoPost 5
Pistol Pete

rrProfessor

Seffner, FL

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ticedoff8
Yes - the digital servos go "limp" with no power (or no input signal), but that does not mean there is no "fly away".
Did not imply otherwise. However**...
ticedoff8
I ejected the flight battery on my old GMP Cobra and it kept flying for about 2 minutes
Did it have digital servos?

...**Depending on heli model such as DFC (with digital servos), blade pitch will increase practically the second they have no power and a "flyaway" is unlikely and means a totally different thing for Japanese.

As is said, the devil is in the details and hopefully we will get more of it. Such as if either model actually idle at all, to which we can "assume" they didnt given his original question about the Rx possible failure.
ticedoff8
That was nitro and not electric - I assume this post relates to eHeli
Anyones guess as he stated ESC (electric) followed by idle (glow) as opposed to OFF. Perhaps one of each.

Hope that clarifies the post and all the related questions to get to the "facts".

~~Enjoying the hobby one flight at a time~~

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04-03-2018 11:48 PM  3 months agoPost 6
Antsis

rrApprentice

Melbourne, Victoria, Australia

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Pistol Pete
Since it was 2 helis with different signal protocols, I will assume both are 2.4Ghz and incidents happened in same location. So, I'm leaning to a lockout.

Was the failsafe tested with blades off and turning Tx off at bench?

Were range test done?

Were both helis set up by same person?

Was it a busy day at field?

Which Spektrum protocol, DSMX or DSM2? If used, satellites same protocol?

We can definitely rule out a brownout. However, we need to find a common denominator.

Do the helis share ANY same equipment? Be it Rx battery, BEC, ESC, Switch (high impedance), Servos and or FBL.

When you bind a Spektrum Rx, by default it will use present stick positions for its failsafe. Thus throtle has to be at whatever position where idle rpm is needed for glow or off for electric. No clue on Futaba.

Were the helis recovered?
To answer your questions. I was not present when both these incidents occurred, but I am VP of the club trying to get to the bottom of this.

Both were 2.4.

I cannot prove this but was assured by the pilots that the failsafe was set and tested.

I was assured range checks were performed. This is a club requirement.

The heli's were setup by different people.

It was not busy. The first flyaway was the only model at the field.

Spektrum DSMX

I don't think they share the same equipment. The first model was a TT titan 50e and the second one was a Trex 450 with stock gear. Maybe the same brand of ESC.

Throttle at idle position (or off in this case with electric), is a mandatory requirement.

Only the Titan was recovered. Subsequent testing pointed to the receiver, but this is not definitive.The 450 was not recovered and we presume it landed in a nearby lake.

There is some doubt in the case of the 2nd flyaway. I questioned the pilot extensively and he said he put the model into hold first and, in desperation, then turned the Tx off.

Ant

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04-04-2018 01:12 AM  3 months agoPost 7
JuanRodriguez

rrProfessor

The Villages, Florida

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Based upon this summary, you’ll never be able to determine what actually happened......as I stated before , doesn’t sound like failsafe was properly set in either case .....

Been there, done that and old enough to know better.....

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04-04-2018 01:55 AM  3 months agoPost 8
Antsis

rrApprentice

Melbourne, Victoria, Australia

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I am certainly of the opinion that was the case for the 2nd flyaway, but cannot prove it without recovering the model.

Ant

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