Never heard of spark control in that
manner but GAMI www.gami.com developed an
aircraft control system wherein the system contains a pressure sensor that
determines the combustion pressures and adjusts the spark duration and timing
from that input. That way they can run 100 oct engines, even turbo charged ones, on lower
90’s car octane gas, amongst other considerations. I believe they are
about to market the system to experimentals in 2005
and are aiming to certify it. It is on the link for product news, it is called
Prism. Here’s their blurb. BTW, these people are the real thing-no fly by
night (so to speak) operation. You can take classes on engine management from
them, using their engine testing cells, and learn a lot by attending one.
GAMI's
Electronic Ignition, PRISM™
PRISM™
(Pressure Reactive Intelligent
Spark Management)
Features:
•Optimized Spark Timing to achieve
maximum brake torque
•Simple, fewer moving parts, fiber optic design
•Increased horsepower at all power settings
•Smoother engine operation- reduces coefficient of variation of
combustion- even on lean mixtures
•More efficient engine operation-CDI produces larger spark at optimized
time BTDC
•Replaces both magnetos- no overhaul required prior to TBO
•Fully redundant design- proven electronic durability with quad redundant
ignition
•Includes GAMI's Supplenator™
Supplemental Alternator- back-up power to primary alternator and battery and GAMI's PDU™
Panel Display Unit
•Automatic detection/prevention of detonation
•Maintains lower peak cylinder pressures- reduced loads on power train
components, longer engine life
•Allows for the future use of lower octane, unleaded fuels. This is the
only system on the millennial horizon that is inherently compatible with lower
octane, unleaded fuels.
•Champion® ignition components (spark plugs, wires, coils)
•Optional panel display of actual real-time horsepower and torque
•Optional digital tachometer
•Optional extensive on-board engine diagnostic capability
•Improved fuel economy- lower BSFCs than
previously possible
•Significantly lower EGTs/TITs for reduced
exhaust system maintenance
FAA STC certification expected soon!
2800
Airport Road - Hangar A
Ada, Oklahoma 74820
phone: 580.436.4833 fax:
580.436.6622 toll-free: 1-888-FLY-GAMI
comments@gami.com
Marc W.
-----Original Message-----
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of rijakits
Sent: Friday, December 03, 2004
6:27 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re:
(unshrouded plug ?)required wrench
Anyone familiar with the old Jacobs
Electronic Ignition systems (Ultra Team)?
It used to be only thing that kept my
oil and fuel guzzling Suzuki alive! If I changed back for the factory
ignition the engine would start to run on 3 cylinders in a very short time (2
min).
Jacobs claimed that his system used
the sparkplug as a " in cylinder"-sensor and that the computer in the
system would adjust the spark on the fly.
This way the voltage went way up for
"ignition" :) and then was reduced according to the requirements in
the cylinder, so as to avoid over current and too hot a spark. In his book
" The Doctors guide to electronic ignition" he mentions, that a spark
can be too intensive and actually blow out a recently ignited flamekernel. We
are talking about the stage BEFORE the little fireball reaches a diameter of
2mm, from where on it is considered a stable combustion. Until that point
things are not certain at all and missfires occure in this stage.
He also mentions that it would be a
breakthrough if it would be possible to have a sparkplug gap of 2 mm to start
the kernel at that stable diameter, however at that gap the voltage would have
to be so high, it would be impossible to isolate the ignition parts in the
confines of a engine or engine room...
Jacobs sold the company (it is still
called Jacobs though...), but as far as I understand their systems use multiple
spark now (like MSD).
I imagine this kind of system would
be great for the rotary as the environment in the combustion area changes a lot
and worse than piston engines.
Does anyone know if there is a similar
system on the market (using the plug as a sensor and adjusting the spark
accordingly?)
----- Original Message -----
Sent: Friday,
December 03, 2004 11:15 AM
Subject: [FlyRotary]
Re: (unshrouded plug ?)required wrench
They should work fine. I just felt that for a system
set up for maximum spark power, I didn't want to have a big resistance in the
plug. I have no idea whether you would ever notice the difference.
I expect Paul Yaw would.
The resistor is
there as a "ballast" to limit the peak current. You need high voltage
to strike the arc, but once the arc has formed, the resistance across it is low
and it takes very little voltage to sustain it. Without the resistor in the
plug, very high current flows, eroding the electrode and shortening the life of
the plug. Also, the high current produces a high magnetic field, causing radio
interference.
The resistor
also helps to increase the duration of the spark. There is a fixed amount of
energy stored in the coil for each spark. Without the resistor, a high current
flows. The energy is then quickly spent, resulting in a shorter spark duration.
Additionally,
you can "burn out" some types of spark plug wires by using
non-resistor spark plugs. The wire can't handle the extra current and goes
open-circuit.
Most cars have
"magnetic suppression" type spark plug wire these days. It is a long
coil of thin wire wrapped around insulating fibers. It acts as an inductor in
the circuit. This tends to make the current much more constant during each
spark.
With electronic
ignition, it is not uncommon to have both magnetic suppression wire AND
resistor plugs. They act in concert to limit peak current, to smooth out the
average current, and to reduce radio (and computer) interference.
If the coils and
ignition control module you have selected were designed to use magnetic
suppression wires and resistor plugs, you would probably be smart in continuing
to use these type plugs and wires. The higher peak current from non-resistor
plugs can also damage the coil or ICM if they are not designed for that use.
Just my eight
cents. :^)
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