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Hi Tracy,
I'd like a set of the fly by wire data you are
willing to share.
When the Diaz variable pitch prop was in play, I
developed a controller for the blades pitch motor which I later modified to
respond to manifold pressure and rpm. Not the same as what you were
developing, but some similar constraints. I won't be flying again until I
get a cataract lens replace in my one good eye ( not in any hurry without a
spare {:>). But, a project like this would be fun to play
with.
But, I do agree, getting something with the potential of
the FBW out into the field is a bit daunting, given my past few years dealing
with users with a wide spread of technical savvy.
Ed
Sent: Monday, March 04, 2013 11:35 AM
Subject: [FlyRotary] Re: Fly by wire
I'm still here Steve (waiting for the Suwannee river to
flood),
The FBW is installed and working (kind of) in the
RV-8 but I decided not to make it a product after two very scary failures.
One was on the ground which caused the engine to go to full
throttle. That was caused by a heat shrink insulated wire connection
shorting to ground where it was tie-wrapped to the fuel rail. Watch
out for this cold flow failure if you use heat shrink insulated wire
splices! Also, know what switches you need to turn off in a panic to kill
the engine.
The second failure was a software glitch in the primary
controller which communicated with the EC3 on the serial bus in order to do
things like Hold constant RPM, MP, Fuel Flow, etc. This one happened on
final approach and the engine stopped responding to the throttle quadrant.
I was only 300 ft AGL at the time and would not have made the runway (I know,
bad landing habits) I regained control by switching to the backup
(it has a redundant controller like the EC2/3). The backup did not have
the serial communication links like the primary and it still worked.
I eliminated the Hold functions and the serial connection to EC3 on primary FBW
to eliminate the failure on it. Now all the FBW does is mirror the
movement of the throttle quadrant at the RX-8 throttle body.
These things
could be fixed but the idea of trying to debug customer problems in the field
with this much digital systems complexity made me decide that it was not a good
idea.
I'll share the schematic & software files if anyone wants to
DIY one. You will need the development tools I use to use them though.
Schematic & PC Board files are in DipTrace, software is in
Microchip MPLAB and uses some PIC BASIC PRO compiler routines as well .
MPLAB is free from Microchip BTW.
Tracy
On Mon, Mar 4, 2013 at 9:22 AM, Stephen Izett <steveizett@me.com> wrote:
Tracy, are you there?
I seem to remember you set up
your Rv8/20B originally with the Rx8 fly by wire throttle.
Did you end up
using it and developing a controller for it?
If so:
1. Are you
willing to share the hardware and code you used?
2. Current
consumption?
3. Most importantly our thoughts on the value or otherwise of
fbw? (true single lever/pot! or perhaps just another failure
mode)
Cheers
Steve Izett
Perth Western
Australia
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