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Ernest,
I have been studying the various Megasquirt
documentaion on the web. Did you use a BAC valve and a TPS? If not
how did you alter the code? Is that something in the tuner software that
is on a menu? I guess TPS could be implemented by connecting throttle
linkage to a variable resistor in a voltage divider. we would not need the
BAC valve. Thanks for any help
Joe Berki
Limo EZ
----- Original Message -----
Sent: Wednesday, May 18, 2011 6:02
PM
Subject: [FlyRotary] Re: Reliably
starting
On 05/18/2011 05:21 PM, josrph berki wrote:
Ernest,
Will you be running Megasquirt for flight or is
it a gound development tool? Do you have any words of wisdom for
someone contemplating Megasquirt? I would really like to see an
electronic analog injection / ignition system developed. Software that
controls the engine scares me. Thanks for any
help.
Analog injection/ignition systems scare
me. Well...not really. All software systems are analog
underneath.
I will be flying with the MegaSquirt, but I can throw it a
lot further than I trust it. But, that is ok. The goal is do
design the system so that it fails gracefully. The MS gives an
incredible amount of flexibility and configuration control. It is REALLY
nice to have. So I take the benefits, but have backup(s).
If the MS quits on me for some reason one day, I have a 3/16" line
plumbed to the throttle body with a needle valve sitting next to me in the
cockpit. I've already verified that on the ground, with gas barely
covering the bottom of the tank, I get flow to the throttle body. I'd
probably never be able to get the engine started with this setup using the
starter, but with the wind still spinning the prop I will be able to slowly
open the valve till I can maintain altitude. Then I can make for the
longest runway I can find.
That's good for fuel, but what about
spark? I'm having the MegaSquirt control EDIS ignition control
modules. The EDIS handles all the VR pickup, dwell and other such
details. These things have proven to be very solid performers during a
decade of use. All MS is doing is getting a tach signal from the EDIS,
and sending back a signal to control advance. Two wire interface.
If the EDIS looses communication with the MS, it falls back to its limp-home
mode which is 10*BTDC. I shifted the VR so that I actually get
25*. But, that just shifts the critical failure from the MS to the
EDIS. I don't have it wired up yet, but eventually I will have two EDIS
modules running, one on Leading and one on Trailing. The second will
have its own power source, driven by the distributor shaft.
Sure, power will degraded if all I have is the trailing plugs and I'm
dumping fuel into the throttle body instead of a proper spray, but it isn't
meant to be a normal mode of operation. It is meant to get me past the
crash site. I don't have to be scared of the software, because I'm not
hanging my life on it.
The only other advice I have is buy one of the
MS3s. They have a USB interface, and can datalog directly to a flash
card. I'm stuck with an MS2 for now. Because of that, I have to
use a 15yr old laptop, because it is the only one I have that has a serial
port.
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