Sudden Loss of Headspeed and then Throttle Hold Doesn't work

[Rockohaulic]

OK - I've got a good one for everybody!

Whatever is going wrong with my Raptor 50 is simultaneously causing the headspeed to decrease signifcantly and the throttle hold to no longer work.

To start with, I don't have a governor, so it's not the governor. The basic scenerio is that I'm flying fast forward, and suddenly the headspeed goes way down. I have my headspeed set at 2000. I'm guessing that it decreases to as little as 1500 rpm. Anyway, I bring her in for a landing, and I notice that the throttle hold does not work. I land it, bring throttle to zero, bring the bird back into a hover, and everything is working again! The headspeed is back to normal, and if I hit the throttle hold, the engine goes to idle like it's supposed to!

I tried this in idle up and flying around in normal mode. The issue would come up in either mode.

This was repeated today several times on several flights! On one flight it was perfect, but then it started happening again on the next flight. The wierd thing is that whenever the engine starts acting up (initially I thought it was an engine tuning issue), i.e. the headspeed suddenly drops, the throttle hold no longer works. I can hit the throttle hold, but the throttle stick still controls the throttle.

Anyway, no one at the field has seen this before. Have any of you seen this???

Rockohaulic.

Oh yes, and everything works fine when flying my other nitro, so I don't think it is the transmitter...

[flyinfool]

When you fly the heli, try having the TX set for the servo monitor screen and when it acts up look to see what the TX is telling the RX.
It still sounds like something in the TX.
The RX does not have the capability of over riding the hold switch on the TX.
It may not be a malfunction of the TX but some goofy mix that's getting you.

[Rockohaulic]

Woo Hoooo! I have an answer. Apparently, the battery low failsafe activated. According to Futaba's website Under FAQ for 9C TX:


Quote
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I was using my radio, and suddenly my throttle servo went to idle. If I pull my throttle stick all the way back and then move it again, it works for a while and does it again. Am I doing something wrong?
Battery failsafe is an automatic safety function of the 9Z computer radio. When the receiver's battery voltage drops below a predetermined cut off (approximately 3.8v) and remains there for more than a set amount of time (several seconds — this allows for occasional hard drains caused by violent maneuvers such as snaps which immediately returns the voltage back to above 3.8v), the receiver recognizes that you are in a dangerous condition, and brings your throttle servo to a high idle. This is a warning that you must safely retrieve the model (land for aircraft/helicopters), as you are reaching a point where there will not be sufficient voltage to operate the receiver.

As an additional safety of this feature, you can pull your throttle stick to idle and readvance it, allowing you to use power to return the model to you, and you will have throttle control for approximately 30 seconds before the feature reactivates, returning the throttle to high idle. IT IS IMPERATIVE THAT YOU LAND OR OTHERWISE RETRIEVE YOUR MODEL IMMEDIATELY BEFORE LOSING CONTROL OF THE MODEL ALTOGETHER.
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[Rockohaulic]

Woo Hooo! I was just now able to exactly duplicate the problem in the comfort of my home. I used my futaba battery checker's discharge funtion to bring the RX battery voltage to about 3.8 to 3.7 volts. Then I turned the TX and RX on, set the throttle at 100%, and cycled the cyclic controls. Sure enough, the throttle soon went to the predetermined position by itself, and once it did that, the throttle hold did not work. Also, once I reset it by lowering the throttle stick to zero, and then back to 100%, in about a minute it went back to the predetermined throttle position.

So the only question remaining us - Why did it do this on the first flight yesterday???

(I could not get it to duplicate until I discharged the battery!!)

[DsWright]

servos drawing to much amperage for the pack, and sagging the voltage.

[BarracudaHockey]

Yep check for something binding, disconnect all your controls at the servo and see if something is dragging somewhere.

[LITHIUMSTATIC]

Guys!!!!! Read what he said!!! Problem solved..... gosh! :arggg:

[BarracudaHockey]

Guys!!!!! Read what he said!!! Problem solved..... gosh!

We did, he said So the only question remaining us - Why did it do this on the first flight yesterday???

(I could not get it to duplicate until I discharged the battery!!)


Gosh!

[LITHIUMSTATIC]

Gosh!!! LMAO!!!