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John asks:
<<<<<" Is anybody on the list using the Watson
AHRS with their Chelton/Sierra Flight Systems EFIS?
I have a Chelton EFIS-SV and Watson but have not installed it yet.
I'd be interested in your comments on the Watson unit? Are you still
using it or have you upgraded to Crossbow or Pinpoint?
"
>>>>>
The CSF software supports the Watson but I would not recommend using
the Watson as it is based on older technology and is relatively easy
to confuse. I used to have a Watson in my IV-P until it developed the
nasty habit of doing aileron rolls every time I encountered some
P-Static. I replaced it with a XBow-500, which has a habit of "seeking"
+- 4 degrees in yaw. I sold the Watson on ebay for about 10 Franklins.
You can sell anything on ebay. I plan to sell the Xbow 500 when I get
around to installing a Chelton GADAHRS.
"Brent, you still running a 500?"
"Yep, the cobbler's kids don't have shoes."
All MEMSs based AHRS (Watson, XBow 425 and 500, Dynon, BM, OP (XBow),
and Garmin 1000) can be "confused" with certain flight maneuvers (e.g.
slow climbing sliding turn) resulting in anything from a few degrees of
offset in yaw, pitch or roll to the aforementioned aileron rolls. One
dealer reports that he has the goods on every AHRS tested with the
exception of the Chelton ADAHRS. The Chelton ADAHRS, so far, is the
only system that has proven resistant to users finding its "secret
handshake" that would cause a perturbation of more than 3 degrees for
more than 90 seconds. When someone does, I'd like to hear about it.
IMHO a reliability and performance ranking, based on anecdotal data and
direct experience, would put the Watson and XBow 425 near the bottom.
Step up to the XBow 500 and Garmin G900x. Another step would get you
the Chelton ADAHRS and the Rockwell Collins AHRS (The RC does not have
an integral Air Data Computer). The last step takes you out of the MEMs
box and into the Fiber Optic Gyro (FOG) platforms like Litef.
What should you use? I couldn't say. What is your tolerance for
spinning displays when you are wings level?
The next question is "How old are, and what is the update status of
your IDUs?". If your system is old enough to have a Watson then it
predates most of the hardware upgrades necessary to run the latest
version of the CFS software. Upgrades include Encoders, RAM, CPU and
Hard Drive. Talk to Chelton if you are unsure. The good news is that
any IDU-I can be updated to the latest performance specs.
Regards
Brent Regan
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