Excellent Carl.  Many thanks.  Just what I was looking for!

John


On 9/8/09 6:23 PM, "Carl Cadwell" <CarlC@cadwell.com> wrote:

> John and Bill,
> I have about 700 hours behind a triple display Chelton with a TruTrak
> Sorcerer autopilot.
> My experience is that I fly the approaches (ILS, VOR, GPS) with the
> Sorcerer in GPSV mode.  The Chelton then drives the Sorcerer.  Use the
> altitude select on the Chelton to track down to the altitudes that ATC
> gives you.  When you level out at the approach altitude, turn off the
> altitude hold and the Chelton then feeds the data to the Sorcerer to fly
> the descents.  The Chelton will display the approach altitude above the
> altitude strip on the right side.   Note:  if you are tracking on
> heading also turn off the heading.  Both of these are turned off by
> pushing the prompts "LNAV" and "VNAV" in the upper left of the screen.
> Disengage the LNAV about 20 degrees before intercept as ATC is turning
> you to intercept the inbound course.  Disengage the VNAV when you are
> ready to track vertically inbound.
>
> The Sorcerer then flies the approaches maintaining both vertical and
> horizontal axis.  You must also dial in the ILS from the Garmin 430 or
> similar.  Then set the OBS on the Chelton so the needles are
> appropriate. Do this when you first pick up the ATIS telling you what
> approach is being used.  Also select the appropriate approach in the
> Chelton and Garmin 430 at this time.
>
> So let the GPSV mode in the Sorcerer fly the approaches and you verify
> everything is correct with the needles displayed on the Chelton.  It
> will fly right down the boxes, perhaps not always exactly in the center,
> but right down the approach course.  Said another way, you are flying
> WAAS enabled GPS for all approaches and verifying everything is a go
> using the ILS/VOR/GS needles.  You have 2 systems that had better be
> displaying the same information.
>
> Note:  I also have WAAS on the Chelton.  The system is terrific.
>
> Carl Cadwell
> Formerly IVP with 1000 hours now an Epic with 700+ hours.
>
>
> John,
>
> Don't know Chelton specifically, but generally speaking the EFIS HITS
> approaches do NOT correspond exactly with the ILS or GPS glide paths -
> they are typically based on a synthetic approach to the approach end of
> the runway at a "standard" approach angle.  Check your Chelton manuals
> to confirm this.
>
> In any event, the ONLY thing you should compare the approach to is the
> glide path / course needles. If they stay centered, the TT is doing it's
> job perfectly.
>
> Regards,
>
> Bill
>
>
> John Hafen wrote:
> 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
>
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