Today's Message Index:
----------------------
1. 09:34 AM - Re: Re: led trim display (Robert L. Nuckolls, III)
2. 10:32 AM - Re: AFR Meter (speedy11@aol.com)
3. 11:17 AM - Re: Re: AFR Meter (DeWitt Whittington)
4. 11:38 AM - Re: Re: AFR Meter (Mike Welch)
5. 04:29 PM - Re: Re: AFR Meter (Robert L. Nuckolls, III)
6. 04:39 PM - Re: Re: AFR Meter (rayj)
7. 04:40 PM - Re: Re: AFR Meter (Robert L. Nuckolls, III)
8. 06:02 PM - Alternator Putting out Max Current (ChangDriver)
9. 07:17 PM - Re: Alternator Putting out Max Current (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: led trim display |
At 07:18 AM 8/29/2013, you wrote:
>Hi Bob
>
>The Europa that I am building uses a Ray Allen for pitch trimming. I
>have read over the years that some folks have the same problem you
>are experiencing when transmitting. It seems that the greatest
>success is keeping the wire run as far from antenna and associated
>wires as you can. I installed 5 conductor twisted with shielding from ACS:
>
>http://www.europaowners.org/main.php?g2_itemId=30484
>
>Ron Parigoris
After pondering schematics for the trim indicator,
the reason for it's sensitivity to RF becomes
apparent. The design was never evaluated and
crafted for immunity to RF interference. There
are critical components missing from the design.
I note further that voltage used to excite the
potentiometer in the actuator is the rudimentary
1.2 volts supplied by the internal reference
regulator. An excerpt from the LM3914 specifications
states . . .
Emacs!
A higher reference voltage increases noise immunity
for the A/D conversion and less jitter or uncertainty
in the bar-to-bar transitions for the display. I would
have considered at least a 5v reference and probably
some higher value still by adding R1/R2 as described
above.
Referring to the data sheet again we see that bias (or
input load) current at the signal pin (5) is 100nA or
less.
Emacs!
This means that we could put a resistor in series with
pin (5) of say 10,000 ohms and exert less than 1 millivolt
of error in the signal voltage. At the same time we would
add say 1000pF capacitor from pin 5 to ground (pin 2).
This mod alone might fix the RF sensitivity problem. As
a matter of good design practice I would bypass the power
input pin (3) to ground as well.
The designers also missed a great opportunity to make
their product truly 'universal' by not exploiting the
expanded scale voltmeter example in the specifications.
Emacs!
Adding a few components and a couple of pots would
allow the indicator to be tailored to a specific installation
such that full down trim would illuminate the bottom led,
full up trim the top led . . . irrespective of the actuator's
as-installed stroke.
I offered to help these guys with this product line at
OSH about 20 years ago but they weren't interested. They
also appear to have learned nothing new by way of feedback
from the field as to how their product has been performing.
Getting back to the original query for driving two indicators
from one actuator pot, a study of the schematics and data
suggests that two indicators running in parallel on one pot
will not significantly 'load' the signal. Hence, you can wire
one indicator to the actuator per installation instructions.
Then wire the second indicator wire for wire in parallel
with the first but leave its potentiometer excitation voltage
wire (orange) floating.
Bottom line is that this indicator would benefit greatly
from due diligence to rudimentary operating characteristics
and limitations. Adding the resistor and capacitor described
above may fix the RF sensitivity issue. The idea that an
installer should be burdened with careful positioning of
wires to mitigate design flaws is decidedly un-cool.
Bob . . .
Message 2
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I suppose I should know about them, but I'm not familiar with measuring th
e air-fuel ratio. The technique is apparently used with automotive racing
engines to fine tune the air fuel mixture to optimize power output.
Does anyone know if that concept and equipment has been applied to an OBAM
aircraft?
It sounds like an interesting and plausible concept.
Stan Sutterfield
Reno Race 84
> snip... I'm already familiar with them and they make good stuff!
> The company is called PLX Devices, and they make incredible high quality
products,
gages,
> etc, mostly for the auto industry.
> snip...
>
> Mike Welch
I can attest to the high quality, simple operation of the PLX's Air Fuel Ra
tio
Meter. Probably the simplest, no-brainer way to tune EFI. I installed a Sim
ple
Digital Systems EFI on a Franklin 6 cylinder and set it up using the PLX de
vice.
Amounted to putting a temporary O2 sensor in the 3 into 1 collector on one
cylinder bank and connecting to the PLX device (velcroed to my panel) and g
auge.
Start the engine and your real-time air fuel ratio is displayed. Change the
mixture (fuel value) on the EFI and watch the gauge reflect the change. Set
it up for 12.5 to 1 max power at 250 RPM increments in the useable RPM rang
e.
Took about 15 minutes to map the 5 point rpm fuel curve.
When I was done, I had the feeling that it couldn't be that simple.
It was.
The gauge is nice looking with it's digital display and progressive LED
"needle",
Message 3
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This is done as standard procedure with Eggenfellner Subaru engines which
have and SDS (Simplified Digital Systems) engine computer.
http://sdsefi.com/ We've installed an AIR/FUEL RATIO knob on our
sub-panel next to the throttle as highly suggested by Ross Farnham, the
owner of SDS. We have an O2 sensor we bought from Ross on our left cylinder
bank exhaust just below the point where the three left cylinders exhaust
stacks merge into one exhaust pipe. We will monitor the AIR/FUEL ratio in
our case with the SDS programmer which we also bought from Ross. Ross, who
is in Calgary, Alberta, Canada, is a wizard with racing Subaru engines.
Dee
DeWitt (Dee) Whittington
804-677-4849 iPhone
804-358-4333 Home
On Fri, Aug 30, 2013 at 1:31 PM, <speedy11@aol.com> wrote:
> I suppose I should know about them, but I'm not familiar with measuring
> the air-fuel ratio. The technique is apparently used with automotive
> racing engines to fine tune the air fuel mixture to optimize power output.
> Does anyone know if that concept and equipment has been applied to an OBAM
> aircraft?
> It sounds like an interesting and plausible concept.
> Stan Sutterfield
> Reno Race 84
>
> > snip... I'm already familiar with them and they make good stuff!
> > The company is called PLX Devices, and they make incredible high quality
> products,
> gages,
> > etc, mostly for the auto industry.
> > snip...
> >
> > Mike Welch
>
>
> I can attest to the high quality, simple operation of the PLX's Air Fuel Ratio
> Meter. Probably the simplest, no-brainer way to tune EFI. I installed a Simple
> Digital Systems EFI on a Franklin 6 cylinder and set it up using the PLX device.
> Amounted to putting a temporary O2 sensor in the 3 into 1 collector on one
> cylinder bank and connecting to the PLX device (velcroed to my panel) and gauge.
> Start the engine and your real-time air fuel ratio is displayed. Change the
> mixture (fuel value) on the EFI and watch the gauge reflect the change. Set
> it up for 12.5 to 1 max power at 250 RPM increments in the useable RPM range.
> Took about 15 minutes to map the 5 point rpm fuel curve.
> When I was done, I had the feeling that it couldn't be that simple.
> It was.
> The gauge is nice looking with it's digital display and progressive LED
> "needle",
>
>
> *
>
> *
>
>
Message 4
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> snip>
> Does anyone know if that concept and equipment has been applied to an
OBAM aircraft?
> It sounds like an interesting and plausible concept. <snip
> Stan Sutterfield
> Reno Race 84
Stan,
My familiarity with them came when I bought their Air/Fuel wideband O2
meter and sender.
The reason I bought the gage is I needed a way monitor the fine tuning
the AFR (air/fuel ratio)
for my custom turbo installation on my GEO engine.
The engine on my plane came as a normally aspirated GEO (Suzuki)
engine. The stock engine control unit
( the ECU) can take care of up to 5 psi boost "automatically". I wanted
a little bit more than 5 (more like 7-8 psi).
Therefore, I used a common practice in the hotrod field is to "trick"
the engine into thinking it is COLD,
thereby adding more fuel. You do this by replacing the coolant
temperature sensor with a simple circuit where you
can determine the resistance the sensor 'was' going to send to the ECU.
BY increasing the resistance, the
ECU thinks the engine is cold. This is known as the CTS mod
(coolant temperature sensor mod).
This method allows one to add a mild turbocharger to an otherwise
non-turboed engine fairly easily.
In addition to the obvious boost gage to monitor turbo boost, you
need an AFR gage to determine
you're not running too lean. If you are=85.you just dial in some more
"artificial cold" to the ECU, and
it increases the fuel injector's pulses, enriching the fuel supply to
the engine.
Anyway, that's how I came across them. They seem to make quality
products. I thought the
'smart battery charger' might be useful to some pilots who carry several
gadgets with them and
could use a great 'safety' back-up charger. FWIW.
Mike Welch
Message 5
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At 12:31 PM 8/30/2013, you wrote:
>I suppose I should know about them, but I'm not familiar with
>measuring the air-fuel ratio. The technique is apparently used with
>automotive racing engines to fine tune the air fuel mixture to
>optimize power output.
>Does anyone know if that concept and equipment has been applied to
>an OBAM aircraft?
>It sounds like an interesting and plausible concept.
>Stan Sutterfield
>Reno Race 84
An engine guru explained the O2 sensor this
Bob . . .
Message 6
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Mark Langford has a Corvair/KR2 site that tells his experience using an
O2 sensor tofine tune thefuel mixture. Well worth the time to look at if
you're considering an O2 sensor.
Raymond Julian
Kettle River, MN.
"And you know that I could have me a million more friends,
and all I'd have to lose is my point of view." - John Prine
On 08/30/2013 12:31 PM, speedy11@aol.com wrote:
> I suppose I should know about them, but I'm not familiar with
> measuring the air-fuel ratio. The technique is apparently used with
> automotive racing engines to fine tune the air fuel mixture to
> optimize power output.
> Does anyone know if that concept and equipment has been applied to an
> OBAM aircraft?
> It sounds like an interesting and plausible concept.
> Stan Sutterfield
> Reno Race 84
>
> > snip... I'm already familiar with them and they make good stuff!
> > The company is called PLX Devices, and they make incredible high quality
> products,
> gages,
> > etc, mostly for the auto industry.
> > snip...
> >
> > Mike Welch
>
>
> I can attest to the high quality, simple operation of the PLX's Air Fuel
Ratio
> Meter. Probably the simplest, no-brainer way to tune EFI. I installed a Simple
> Digital Systems EFI on a Franklin 6 cylinder and set it up using the PLX
device.
> Amounted to putting a temporary O2 sensor in the 3 into 1 collector on one
> cylinder bank and connecting to the PLX device (velcroed to my panel) and
gauge.
> Start the engine and your real-time air fuel ratio is displayed. Change the
> mixture (fuel value) on the EFI and watch the gauge reflect the change. Set
> it up for 12.5 to 1 max power at 250 RPM increments in the useable RPM range.
> Took about 15 minutes to map the 5 point rpm fuel curve.
> When I was done, I had the feeling that it couldn't be that simple.
> It was.
> The gauge is nice looking with it's digital display and progressive LED
> "needle",
>
>
> *
>
>
> *
Message 7
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At 12:31 PM 8/30/2013, you wrote:
>I suppose I should know about them, but I'm not familiar with
>measuring the air-fuel ratio. The technique is apparently used with
>automotive racing engines to fine tune the air fuel mixture to
>optimize power output.
>Does anyone know if that concept and equipment has been applied to
>an OBAM aircraft?
>It sounds like an interesting and plausible concept.
>Stan Sutterfield
>Reno Race 84
An engine guru explained the O2 sensor to me
at OSH a few years back. It response to the
presence of any oxygen in the exhaust gas stream
and unless fitted with an electrical heater,
doesn't give out useful information until it's
warmed up by the exhaust.
The output voltage is a function of oxygen
concentration . . . so any mixture running
lean will use up all the fuel with oxygen
left over . . . hence some voltage will
be generated. Stoichiometric mixture will
produce zero volts . . . mixture richer
than stoichiometric will also produce zero
volts.
These sensors have been used on OBAM aircraft
for many years. Contrary to popular myth, leaded
fuel doesn't seem to 'clog them up' . . . I've
met two pilots flying them in 100LL fueled aircraft
with useful performance. In both cases, adjusting
mixture for xx.x millivolts on a display produced
an accurate and repeatable setting of 'xx degress
lean of peak' . . .
The agile fuel injection computer can be fitted
with mathematical smarts to extrapolate injector
timing for performance goals on the rich side of
stoichiometric.
The output voltage is, as I recall, small . . .
tens of millivolts. Useful application usually
calls for some active signal conditioning
for presentation on a display.
The short answer is, "Yes, an automotive O2
sensor can be a significant component of your
operating design goals.
Bob . . .
Message 8
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| Subject: | Alternator Putting out Max Current |
I have a 35 Amp B&C alternator on an experimental aircraft. Also installed is
the B&C regulator. I went thru the troubleshooting guide and all voltages are
in spec. But, when running the engine at takeoff power, the alternator is putting
out 35 amps. Bus voltage is regulated at 28.8 but the current is maxed
out. This has never happened before. Any insight into where to look for the
problem,
Thanks!!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=407797#407797
Message 9
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| Subject: | Re: Alternator Putting out Max Current |
At 08:01 PM 8/30/2013, you wrote:
>
>I have a 35 Amp B&C alternator on an experimental aircraft. Also
>installed is the B&C regulator. I went thru the troubleshooting
>guide and all voltages are in spec. But, when running the engine at
>takeoff power, the alternator is putting out 35 amps. Bus voltage
>is regulated at 28.8 but the current is maxed out. This has never
>happened before. Any insight into where to look for the problem,
If the voltage is normal (I presume this is a 28v airplane)
and the alternator is maxed out after starting the engine
then your battery is probably dead and the alternator is
running full bore to get it recharged.
Bob . . .
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