Snip-----------


David -- Check with Tracy on the EM3.  The 20B powered
RV8 does
use the electronic throttle.  Tracy mentioned he
didn't want to
release any details until he had flown with some hours on
the
system.

With an electronic throttle controller, I could build a
simple
one in a few hours, as I have done this before. Building is
one
thing, validating and testing is quite another.  Add
support and
it suddenly becomes a 500 hour project. :)  For a
vehicle it
reduces a number of subcomponents (aux air valve, cruise
control,
cable and linkage - NVH reduction, in additon to emission
or
engine saving mode (i.e. built into the Corvettes to
prevent
your 16 you old son from borrowing the car and spinning
high-G
donuts until the engine is starved of oil... hence in that
case
it will reduce throttle slowly as few onramps have more
than 360
degree turns!)

Older systems used an idle control valve. Simple PWM or
stepper
motor to control the amount of air bypassing the throttle
plate
to keep a steady idle. I did make a system to replace the
BMW
VDO module, but didn't want to mess with liability, so it
was
simplier to repair the OEM system than replace it with my
own
controller.

With aircraft and a throttle control cable, there isn't
much
need as we only are at idle a few times before and after
flight.
One thing I recommend is that if the cable is detached, or
slips
out of place, is for the throttle go to WOT (Wide Open
Throttle).  Much easier to return to an airport at
WOT, and just
kill the engine once in the pattern. :)  I was looking
at a few
Rotary Powered planes and noticed the stock spring for
"return
to idle", when I asked the pilot about it he commented
"never
had an issue, so it is fine that way".


Tom Walter

--

Tracy said effectively the same to me - that was over 15
months ago
I have reached a point where while I would like to use it,
it appears
that it is still not available. I have to do something in
the next
few weeks so I can progress further.

Tracy's - Has something changed recently?

Hey Tom, I'll take the Circuit you mentioned
I'll deal with the support as it is a one off anyway :)

Otherwise, I guess I'm at cable conversion.

WOT on a Gyro would be very BAD, rather some where around
cruise would
be the better choice.

Regards David

David,

Another thing to keep me awake a night... planning the perfect
electronic throttle controller, with every detail thought of.
Once soundly asleep I'll wake up with "Gyro, gyro.... I never
even thought of it being mounted on a gyro"

For aircraft is does bring up an interesting thought... if you
are approaching VNE, should the throttle start closing?
Personally I like
the big red knob (other than when it comes off in my hand!) to
open and close the throttle on the plane.

The Circuit is a simple uC with a PID loop.  Part of the reason
I never took it too far was little things like the weight of a
flywheel, or flex plate, had to be considered.  A simple
"resistor" was a neat way of programming the "weighted value" of
such, but the more I messed with it the more I became convinced
of the nightmare.  On my production vehicles, if you leave the
idle switch closed, the engine will sense high rpms and realize
something is wrong... shutting off fuel control. So for a
electronic throttle to be fairly fool proof, it needs should be
part of a larger system.

Irony is the BMW write up (from 1992) about my neighbors BMW
with the crazy idle is still on the 'net.
http://www.unofficialbmw.com/repair_faqs/idle.html


Tom