Cant seem to arm heli through radio

Hi All,

I'm trying to get my first ArduPilot up and running on a TREX600. I've just flashed my APM2.5 board with Trad Heli 2.9.1 through the mission planner and I think I have everything setup right. Everything moves where it is meant to move.

My biggest problem right now is that I have to arm the helicopter via a laptop. With my throttle stick at zero (flying mode 1) in Normal flight mode, i can hold the rudder or aileron to either side all day long without it arming.

I have a feeling this is because my normal mode is set to -4 degrees pitch on the blades, with idle 1/2 getting full throw - but at the same time full motor power.

Is there any way I can arm a helicopter without my "throttle" at zero? If I switch to Idle 1 or 2 the motor is going to spool up to 75 or 85% which is, I believe, the opposite of what the Arm/Disarm is meant to be doing for me.

I have a Futaba T9CAP, with the pitch on CH3, and throttle on CH6. I've simply used the pitch curve for throttle, and the throttle curve for pitch so the channel assignments are correct.

Should I set a throttle hold mix to drop it to 0?

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  • did you ever find out the cause? Mine is not arming. Driving me nuts.

    • Developer

      Maybe it's because ch8 isn't raised so it doesn't think the main rotor is turning?  Rob Lefebvre is the main guy on heli by the way.

      • Got it going. CH8 switch was too low at 948 when my collective stick low was 1000. I had to change the weight of the CH8 in the 9XR transmitter from 100% to 95% so that CH8 low is now 1000. Then recalibrated the radio in APM.

  • Yeah, the problem is you are using throttle curves in the Tx, and you should not be.  You should not be using those in the Tx, and instead let the APM do that job.

    Are you using a governor ESC?  You should be as that is the easiest.  It eliminates all the trouble of trying to get the pitch curve right, because that's almost impossible to do.  Soon as you put it in an auto mode, all your Tx throttle curves go out the window.

    So there is no Idle-up modes.  The ESC is either on or off, and you always have full throw on the collective pitch.  You can add a bit of exponential or collective curve if you want, but that's it.  No variable endpoints.

    To soften the collective pitch range in stabilize mode (ie: not an Idle-up) you use H_Stab_Col_Min and Max.  That is how you limit the negative collective to -3° or whatever you want.

  • Developer

    I think you need to be able to get your throttle to zero.

    Maybe you can set a switch on your tx that allows you to easily adjust the bottom of the throttle range?  flick it on and it lets you get to the bottom, flick it up and it's the regular range that you want?

    Normally though I thought we didn't want people adding throttle curves to their tx.

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