ArduPilot - First Flight

Ok, I've spent the last few weeks putting together my ArduPilot and plane.  It's running ArduPilot 2.7.1 in "Stabilize" mode.  The first flight was not very stable, possibly due to the fair amount of wind, but also because the ArduPilot is not tuned.  I've read the manual and have some observations/questions for anyone who can answer.
1. I'm running on a plane, Sky Fly Max by Hobbico, that is a boom type plane with ailerons, rudder, and elevator. I've modified the wing so it's about 52" wing span.  I'm using X,Y, & Z sensors from FMA.  My Z sensor is a second thermopile from FMA.  The AP is setup to use the Z sensor and the X,Y is configured to be "Right Side Up" with the connector facing forward.  That is how it was installed, when I tested the AP the roll compensation was the opposite to what it should have done.  As I recall the pitch was correct.  I ended up making the sensor face backward from the setting in the ArduPilot configuration.    Any Ideas?
2. Having read the manual and many posts, I know I can use the second Thermopile as the Z sensor.  I have found no orientation settings for this sensor.  Obviously, it should have a set of thermopiles facing up/down.  How do I know which pair is the one that is being used for the configuration of the AutoPilot?  The main sensor moves the controls when I put my hand in the way for it to read it, but that doesn't seem to happen on the Z sensor?  Anyone know how the FMA XY sensor should be positioned for use as the Y sensor so the thing works correct?
3. There is Roll and Rudder PIDS in the ArduPilot configuration that can be tweaked.  If I'm running Ailerons doe I modify the rudder settings? Are they in use?  When ailerons are in use I'm thinking they are tied to Roll.  Am I incorrect?
Just a shot of the ArduPilot on my bench.
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  • I would *always* start off in manual. Make sure the plane is properly trimmed, then switch it into one of the modes. I'd start with stabilize, then FBW, then the RTL/loiter/auto functions that use the GPS.
  • Moderator
    Graham, what plane are you flying?
  • Moderator

    Glad to see a few others using the (now legacy) ArduPilot, I was beginning to think I was the only one. I have played around with this more than I'd like to admit, but it actually flies pretty darn well and the navigation when tuned works amazingly well.

    I've done FPV Nav guided flights out to 2.8km from home with a standard Hitec Aurora 9 and Optima 7 receiver. Using FBW_A is also fantastic for FPV because it's almost impossible to get the aircraft into an undesirable attitude.

  • Moderator
    Actually the entire flight was with the AP enabled. I flew today using a different plane and my trims on the radio were WAY off. Even though this was a different model on the radio the other plane acted very much like the flight yesterday. I think I'll try it again and see how it goes after I trim the model out in regular RC.  I'll check the config to see if my roll is set to reverse like the example (default?).  Thanks I missed that.
  • in your videos it also helps if you annotate a bit in youtube when you're switching modes, not seeing what you expect, crashing uncontrollably, etc....
  • I also have a thermopile setup like this, but in an easystar.This is where I always change my roll response. I have XY with cable facing forward. I also have a FMA Z sensor. Only 2 of the sensors are used and should be pointed up and down. Don't worry if you don't get what you expect by covering things up on the Z. Set it up, take it outside, I use stabilize. Put it in stabilize and test the pitch and roll response on the ground. Leave the PIDs alone for now.

    #define MIXING_MODE 0 //Servo mixing mode 0 = Normal, 1 = Elevons (or v tail)

    #define REVERSE_ROLL -1 // To reverse roll, PUT -1 to reverse it
    #define REVERSE_PITCH -1 // To reverse pitch, PUT -1 to reverse it
    #define REVERSE_RUDDER 1 // To reverse rudder for 4 channel control setups

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