Gents:

In my IVP, I have a Trutrak Sorcerer Autopilot wired to a Chelton twin screen system.

I shot a few GPS approaches today and everything seemed to work ok, except that the decent after the IAF seemed to lag behind the HITS green squares.  The plane was going down, on the “glide slope” but not as aggressively as it should have.  Kind of hanging out near the top, or slightly above the green boxes.  It was a GPS approach that I initiated by hitting the GPSV button on the Sorcerer.

I know that altitude transitions can be made by airspeed, vertical speed, or horizontal distance (VNAV).  So if my descent was lagging, I wonder if I need to go into Pitch Setup mode and play with the vertical activity or vertical torque.  Or some other parameter.

Or is there a way to specify a certain airspeed or V-speed for the descent — or is it just supposed to center the boxes.

I apologize for rambling a little here.  I suppose my fundamental question is how to make the auto pilot fly the descent right in the middle of the green boxes......  What Am I Missing?  

Many thanks and Regards.

John Hafen
IVP N413AJ 175 hours