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-