Update python models to have accurate constants

This should bring the python models all up to date.  Thanks Sarah for
pulling some of these out of the CAD.

Change-Id: I948685629b8d6835dccd72e623bf110525cb4254
diff --git a/y2020/control_loops/python/accelerator.py b/y2020/control_loops/python/accelerator.py
index 257ed23..e5b26fb 100644
--- a/y2020/control_loops/python/accelerator.py
+++ b/y2020/control_loops/python/accelerator.py
@@ -13,17 +13,27 @@
 
 gflags.DEFINE_bool('plot', False, 'If true, plot the loop response.')
 
+# Inertia for a single 4" diameter, 1" wide neopreme wheel.
+J_wheel = 0.000319
+# Gear ratio between wheels (speed up!)
+G_per_wheel = 1.2
+# Gear ratio to the final wheel.
+G = (30.0 / 40.0) * numpy.power(G_per_wheel, 3.0)
+# Overall flywheel inertia.
+J = J_wheel * (
+    1.0 + numpy.power(G, -2.0) + numpy.power(G, -4.0) + numpy.power(G, -6.0))
+
+# The position and velocity are measured for the final wheel.
 kAccelerator = flywheel.FlywheelParams(
     name='Accelerator',
     motor=control_loop.Falcon(),
-    G=1.0,
-    J=0.006,
+    G=G,
+    J=J,
     q_pos=0.08,
     q_vel=4.00,
     q_voltage=0.3,
     r_pos=0.05,
-    controller_poles=[.87],
-    dt=0.00505)
+    controller_poles=[.87])
 
 
 def main(argv):