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


Most airplanes have a Red Mixture nob, a Blue Prop Control,
and a
Black Throttle..  :)


Matt-



Right after I posted that.... doh! :)

Tom