message: Better approximation to Iris motor distances
diff: /*
  * MultirotorDynamics implementation for 3DR Iris
  *
  + *
  + * Uses CLeanflight QuadX motor layout:
  + *
  + * 3 1
  + * X
  + * 2 4
  + *
  * See: https://charlestytler.com/modeling-vehicle-dynamics-6dof-nonlinear-simulation/#Equations-of-Motion
  *
  * Copyright (C) 2019 Simon D. Levy
  @@ -16,15 +23,15 @@ class IrisDynamics : public MultirotorDynamics {
  double _motorvals[4];
  - // Motor distances from center of mass
  - double d1x = 1;
  - double d1y = 1;
  - double d2x = 1;
  - double d2y = 1;
  - double d3x = 1;
  - double d3y = 1;
  - double d4x = 1;
  - double d4y = 1;
  + // Motor distances from center of mass, in meters
  + double d1x = 0.150;
  + double d1y = 0.240;
  + double d2x = 0.150;
  + double d2y = 0.225;
  + double d3x = 0.150;
  + double d3y = 0.240;
  + double d4x = 0.150;
  + double d4y = 0.225;
  protected:
  