I think I'm catching on finally! Since an electric pump can be adjusted
independent of RPM (which a mechanical pump can't do) you've moved towards

a

much less complex, but still very functional fuel injection system.

Phil Williamson

  I have yet to notice a crummy idle with the Continental (Bendix) system.

Idle is excellent. Both systems have pumps that can deliver more than the
engine
can ever use. The Bendix operates at very low pressures and as long as the
engine
is turning, will continue to operate without any electrical power. The
mixture is
controlled by minor fuel pressure changes (about 6 to 12 pounds) controlled
by the
pilot with the mixture control beside the throttle.

Most of the Bosch K jetronic copies/clones use 30 to 60 PSI controlled by a
mechanical regulator mounted close to the injectors. Fuel pressure is the
same all
of the time, and mixture is controlled by increasing or decreasing the "ON"
time of
the injectors. Injection is timed and under the control of a computer.
Mixture control and atomization are better, and may be tailored by having multiple
injectors and or different delivery rates and different locations in the inlet
tract. An extra battery isolated except for charging, just for emergencies
would even the score on reliability.

Airplanes don't spend many hours idling, and both systems have acceptable
idle performance. If you have to pay average retail for a complete used Bendix
system, then the only choice is Tracy's system. Same or better performance and
far cheaper. Also there is online help with tuning and installation. Try for
that with the Bendix.

Lynn E. Hanover

"Crummy idle" may have been a bad choice of words on my part. :) But, as
you stated, an aircraft spends little time idling. All I was trying to
say (with this new-found knowledge, thank you Paul :) ) was if a "not so
smooth" idle is the only down side to a dribble system, when I get
around to building my motors, I'll be looking close to this way of doing
things.

I'll be using twin engines (with fixed pitch) on a helicopter....
reliability is a must!

 
The AirCraft Rotary Engine NewsLetter.  Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/            
Copyright 1998-2003 All world wide rights reserved.