A few questions before my first flight.

Hi, I just purchased a pixhawk, but decided I'd go ahead and try out my APM2.6 first since it's been collecting dust. I'm using the 3dr Hexa frame.

I've flow rc planes and variable pitch helicopters, but have no experience with multi-rotor copters or autopilots.

I just have a few questions before my first flight, which will hopefully be this weekend. The goal is to have this working by a work gathering on the 30th.

1. Is it a bad idea to put the receiver on an arm under a prop? Just wondering if the airflow moving the receiver's antennas will be a problem. My thinking is that it would keep the receiver away from other components.

2. Is it okay to use a combination of different ESCs? I have 4 ESCs that are 20amp(3dr) and 2 ESCs that are 30amp(other brand). Both are using simon firmware and actually the boards look about identical. My current limited knowledge tells me that using a 30amp would be fine since it's higher than the 20amps designed for the motors. Note: The generic 30 amp ESCs fire up at a higher throttle level(slightly) than the 3dr 20 amp ESCs. I've recalibrate using the all at once and one at a time methods with the same result.

3. I'm using a 3dr power supply power module with the old APM2.6 stuff. It currently only shows voltage but not current. Is that a problem? I've tried several settings modifications but can't get it to show current.
4. I don't have a sonar module, but am curious what all it does. I'm assuming it assists in landing and lower altitude position hold etc. Will auto landing work fine without it? Does it use barometric pressure to land without it?

5. When I push right on yaw or roll, the graph on the radio calibration tab moves left. I'm assuming I need to reverse those channels in my Spektrum DX6, but I wanted to confirm that is the right place to do it.

Thanks in advance for any assistance. I'm really excited about getting this thing in the air!

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  • As long as the RC RX's wire antennas don't get into the rotors they should be fine.

    Theoretically you should be able to use different ESCs for the motors and be OK. The APM will keep changing whatever command it's sending to a motor until it gets the results it wants. Still, I'd try my best to use the same model ESC for each motor.

    In Mission Planner under "Optional Hardware" you should be able to select the monitoring of both voltage and current. 

    The sonar module simply gives the APM a more precise distance to the ground. They can be tricky sometimes and may be prone to noise. Most people don't find them terribly useful. They aren't needed for autoland. Autoland uses a standard descent rate until it gets to some preselected height above the altitude it was armed at, then slows to a much genteler descent. When it stops descending (i.e., it hits the ground), the motors will stop.

    I wouldn't reverse your Tx yaw or roll  channels unless the copter actually exhibits reversed behavior while in flight.

    • Thanks for the reply!

      I have tried selecting voltage and current in the mission planner but I never get current.

      I haven't flow the copter yet, but at my desk with no props when i push left, the left motors rotate faster. So it seems like I do need to reverse the channels. The same happens if I attempt to make the copter go forward, the front motors go faster and the rear go slower. It appears to be doing the reverse of what I want it to do.

      Odd considering it's a name brand receiver and I haven't changed any of those settings in the mission planner parameters. I would think it would be a standard by now, but who knows.

      That being said, I am using a PPM converter, so maybe that has something to do with it.

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