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Optimising the QuadYCopter

There's a few things I'm trying out to get the QuadYCopter as stable as the QuadCopter is;

• Three Blade props
• 4S Battery
• Shorten the front arms
• Restore the PID values to default
• Custom code.

 

By far, the biggest change / improvement has come from using Three bladed props and a 4S battery. Some might argue a well balanced two bladed prop is just as good as a three bladed but in my experience, the 3 blades seem much easier to balance. The 4S battery also makes a huge difference to the throttle response. It's much zippier and for example when I jockey the throttle on 4S, the Quad actually jumps and dips. When I do the same on a 3S battery, the response just isn't there and it's sluggish. 

 

I'm trying modified code specifically for Y4 V-Tail I found in the forums here http://www.multiwii.com/forum/viewtopic.php?f=8&t=665

The default code is;

 

#ifdef Y4

    motor[0] = PIDMIX(+0,+1,-1);   //REAR_1 CW

    motor[1] = PIDMIX(-1,-1, 0); //FRONT_R CCW

    motor[2] = PIDMIX(+0,+1,+1);   //REAR_2 CCW

    motor[3] = PIDMIX(+1,-1, 0); //FRONT_L CW

  #endif

The modified code is;

#ifdef Y4

    motor[0] = PIDMIX(+0,+1,-1);   //REAR_1 CW

    motor[1] = PIDMIX(-1,0, 0); //FRONT_R CCW

    motor[2] = PIDMIX(+0,+1,+1);   //REAR_2 CCW

    motor[3] = PIDMIX(+1,0, 0); //FRONT_L CW

  #endif

Today I moved the two forward motors back on the arms so they're equal distance from the centre as the two rear motors. Initially I had them further forward to counteract the weight imbalance of having two 'sweptback' arms but with proper battery placement and I want to use a GoPro up front, I don't think I need more weight up front.

I restored the PID values to default but still get some osciallation in "stable" mode. before I lower P any more, I need to see what the effect of moving the motors has.