REFLECTOR:S-Tec modifications
Chuck Jensen
reflector@tvbf.org
Tue, 11 May 2004 11:29:19 -0400
An apparent advantage of the TruTrak Digiflight A/P is it allows a range of
value inputs during setup/programming to control roll and pitch (two
separate values) to dampen/kill loss of movement/oscillation issues. In
short, this setup input takes the place of the variable resistors and wires
hanging around with S-TEC. I would brag on how great the TruTrak flies but
I'm not there yet so I won't. However, the TruTrak does seem to offer a $0,
0 hassle, solution to the oscillation problem.
Chuck
-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
Behalf Of Jack Sheehan
Sent: Tuesday, May 11, 2004 9:53 AM
To: reflector@tvbf.org
Subject: Re: REFLECTOR:S-Tec modifications
Here is an update on the S-TEC autopilot roll oscillation problem I
was having with the S-TEC 30.
Based on Mack's advice and after talking to Kenny at S-TEC I removed
the Turn Coordinator and roll computer from the aircraft. S-TEC
replaced the gain resistor with a variable resistor in each unit (
the size is different for each unit) I asked them to put the variable
resistors on a 15 inch wire so that I could mount the resistors below
the turn coordinator. The unit was returned with the variable
resistor set at the factory setting. Yesterday I reinstalled the
units and went for a flight test. I engaged the autopilot in the ST
(wing leveler) mode and the oscillation (side to side) was as before.
I have not mounted the variable resistors but just have them hanging
from under the instrument panel. With the autopilot engaged and the
side to side oscillation in progress I turned the roll resistor
slowly counterclockwise until the oscillation stopped. I then engaged
the altitude hold and the pitch oscillation was not as bad as roll
but a similar adjustment has the pitch working fine.
I will fly for a while in different configurations to make sure all
is OK. I don't think I will mount the resistors but probably just
secure them under the instrument panel.
The S-TEC 30 I purchased from Velocity I installed with the
assumption that it was a plug and play since I had specified the
heading gyro etc. This is not the case as I am finding out. The
wiring harness is set up for interfacing to the S-Tec gyro so there
are other things such as jumper wires etc that need to be changed. I
am still trying to understand that stuff but the oscillation problem
has a solution.
I had a little bit of a problem with S-TEC concerning the cost of the
modification. In talking with the technical folks it was " just send
it in and we will fix it" . After the modifications were done they
wanted to charge me and not cover it under warranty. My autopilot is
a few years old but as far as I was concerned the date of
installation has yet to occur because the installation is not
complete until it works. They did after some discussion cover it at
no charge. The proposed bill would have been $275. So if you have an
STEC under warranty get that recognized up front.
Jack
N55XL
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