Paul, the following statement was posted on the Tailwind discussion
group. Do you think it is true and how would you explain such
performance? Jerry
Just found this: lsecorp.com, then click on news on left side. Klaus
Savier flew the Vari-eze nonstop from Santa Paula, CA to Panama City,
FL, 1985 statute miles in 8 hrs 58 min on 25.8 gallons. Slightly under
80 miles per gallon.
Its true. Klaus had a strong tail wind. As I recall he also had oxygen :)
He leans his engine severely and advances the ignition. He also uses
a high energy multi-spark capacitor discharge ignition system to
fire the lean mixture. Another factor is the aircraft is highly
refined aerodynamically. Yet another factor is he uses solid state fuel
injection but it is not computer controlled. Cheap analog circuits (cost
$1 each)
called 555's or something similar are used to change the pulse width
on the electric injectors. Each cylinder gets the same amount of fuel.
He may be
able to adjust the fuel on each cylinder individually according to the
EGT. You have
plenty of time up there to diddle around.
Paul Lamar ...No rotor no motor.
Paul,
How do the chips know how much fuel to deliver does it work on RPM or
throttle position or something like that?
George ( down under)
I am not exactly sure about all the details but with a fixed pitch prop
you could probably
get away with RPM alone. You only really have two RPM points where you
need precise
mixtures, climb and cruise. You could manually adjust for those two
conditions.
Paul Lipps probably designed the system. The attached schematic diagram
for a rotary
uses a throttle pot. I have attached another 3D showing a way to make a
throttle pot device.
Freescale manifold pressure sensors could also be used.
Paul Lamar ...No rotor no motor.
Paul,
You did it again! (I am referring to a correction sent about 6 months
ago.)
Check your 555 graphic in above email.
Don't put TWO tabs on your "timing wheel" - use just ONE. The ONE tab
needs to rotate around (at e-shaft speed) to trigger the two separate
injector circuits 180* apart.
As shown in your graphic, you will fire both injector sets
simultaneously (for rotor 1 and rotor 2) twice per revolution.
Normally I would just lurk, but the Wankel confuses enough people
already. (It shouldn't - it's simpler than a piston engine.)
FWIW.
-Vince Orton
True. Sorry. Is that your diagram or mine Vince?
Well I had it lying around so I used it. The subject only comes up once a
year or so. I probably never bothered to redraw the diagram.
How's this?
There is another mistake in that two injectors are fired for each rotor
while only one power transistor is used. I would use one power
transistor for
each of four injectors instead.
----------------------------------------------------------------------
Here is some more info on the little jewels.
--
Paul Lamar ...No rotor no motor.
And for a negative opinion:
------------------------------------------------
Subject: Super simple 555 based fuel injection system
From: Rotary Engine
<rotaryeng@earthlink.net>
Date: Tue, 02 May 2006 16:14:19
I have actually built an electronic fuel injection system. It is a lot
more complicated than this.
You have to change the duty cycle with manifold pressure. The engine
won't run unless you do this, at least in a simple fashion.
You have to change the duty cycle with RPM. Again, the engine won't run
unless you do this at least in a simple fashion.
The throttle position alone isn't enough to set the duty cycle. The
engine won't run.
In theory, you could sense the intake air mass flow and set the duty
cycle based on that alone. (Manifold pressure and RPM together allow you
to estimate mass flow.)
I think you would be better off with a hand-controlled needle valve than
you would be with a 555 based EFI.
Bill Dube'
---------------------------------------------------
Bill overlooked the fact that the pulse rate is directional proportional
to RPM as there is a shaft sensor that triggers the 555.
He may have a point about throttle position. Perhaps it is easier
and cheaper to use manifold pressure to change the pulse width.
I'll look into to it and see if I can come up with a circuit that works.
I don't want to use mass air flow alone as that implies mass airflow sensors
that restrict the intake flow.
--
Paul Lamar ...No rotor no motor.
Hi Paul,
If you work with a mass airflow sensor, don't you get altitude
compensation (aka leaning) for free? Dave M
Not the same thing. Yes you want altitude compensation but you need leaning
beyond that. Most pilots are used to compensating for altitude by manual
leaning. Those that don't sometimes crash when taking off from high
altitude airports :)
Paul Lamar ...No rotor no motor.
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