EAT

I have a new USL120 with RCS140, I have only 6 flights on it. After two good flights I was tuning low speed idle on engine all the servo's pegged and locked. I immediately turned the plane off then back on, had no control with radio at all. My radio is a Futaba 9C PCM with R149DP rec. I checked all plugs and wires no problems that I can see. Can anyone advise on what caused this to happen and how to resolve?

twostroker

My Feedback: (37)

Did you have your "fail safe" set up?

Are your servos and receiver 12"+ away from the ignition system?

Do you use a metal push rod for your throttle?

Sorry for all the questions but it will help get to the problem.


Tim

EAT

Thank you twostroker for replying,yes the fail safe is set up to idle down the engine,and close the choke, but it did not. The engine
kept running until I turned the ignition off. I have tested the fail safe before by turning the radio off and it did kill the engine.

The receiver and battery are 12.5" away from the ignition. I use a plastic rod for the throttle and choke. I'm using 8 servos and I've had to charge the batteries after every flite. My receiver pack is a 1400 4 cell.

Its weird on my trainer I would have to fuel after each 10 min. flite and recharge after 4 flites. On the stick I get 4- 10 min., flites on a tank of fuel and have to recharge after each flite.

Thanks again for your time.

Eric

twostroker

My Feedback: (37)

Are you using the same battery for the ignition and the rest of the plane?


Tim

EJB

I was setting up my new plane with the 9C & a Hitec rx (PPM)& it would intermittently go nuts.Finally figured out that I did not set it to PPM .
Make sure that it's still on PCM with that R149DP.

EAT

Hi Tim, I have two Batteries one for the ignition and one for the receiver both are 1400 4-cells.

And EJB Thanks for the responce the radio is set on PCM

Thanks

Eric

twostroker

My Feedback: (37)

Beats me what the problem is....something isn't right. Did you try a different RX battery yet. I did see a plane take what we thought were multiple hits one day only to find out one of the battery tabs came loose on one of the cells. That was a PCM system also, JR but still PCM. The plane did some crazy stuff in the air and on the runway after landing. I do not know how he landed it..pure luck.

Tim

GalenB

My Feedback: (18)

What servos are you using? Draining a 1400 mah battering after 10 minutes of flying is very bad. Do you perchance have a stalled or binding servo, most likely the choke, that is causing your battery to rapidly discharge? As I write this I am wondering how a choke servo would work... It is my understanding that a servo only consumes a lot of power when it is moved, and it consumes much less at neutral. What is neutral for a choke servo? It seems to me that a choke servo is much like a retract servo... I assume that retract servos when properly setup do not consume much power at their endpoint...

shenion

Servos don't care what position they are in.

Analog servos generate a pulse from the pot connected to the output shaft. It is compared to the incoming pulse. The difference is sent to the moter. So the more the servo is off the position desired, the more currrent it will draw (the longer the pulse is sent to the motor.)

If there is binding, the servo will continuously try to get to the position. The moter will continuously draw current trying to hold the position against the binding. Once the motor starts moving, it draws less current. A stalled servo will likely overheat an kill your batts. They are never designed to operate this way.

Digital servos are similar, but thir current is less dependant on the difference in the position from the radio and the output position. The main difference is digtal servos canl draw much more current to move a small distance. Also their position is updated more freqently.

As to the original problem, it sounds like something shook loose in the receiver.

Geistware

My Feedback: (16)

Either the receiver or crystal may be bad.
If all the servos did this, I would think the problem is the receiver.
I would have it checked out.