Today's Message Index:
----------------------
1. 10:42 AM - AOA (Eric M. Jones)
2. 12:51 PM - Dimming of UMA EL Light Strip (Yabergs4@aol.com)
3. 02:38 PM - Re: LED position lights. (Eric M. Jones)
4. 04:53 PM - Re: AOA (Paul Messinger)
5. 09:45 PM - Re: Dimming of UMA EL Light Strip (Tammy and Mike Salzman)
6. 10:54 PM - Re: AOA (william mills)
Message 1
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--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
>--> AeroElectric-List message posted by: Sigma Eta Aero
<sigmatero@yahoo.com>
>This little bugger looks about perfect for the job and seems to be priced
pretty
>well. Since output is a function of input wouldn't you have to supply a
regulated
>and constant 5.0VDC to it and if so what is the easiest way to accomplish
>this?
>Joa
Plan on using the stock part HRS100SSAB90. You should be able to get one
from www.potentiometers.com
The part is ratiometric, which means it puts out 4.8V at some angle with
5.0Vcc input. But if the input sags to 90% of what it was, then the output
is 90% of what it was. A designer can use this fact to allow the use of no V
regulators.
Buy Forrest Mims' engineers notebook at Rad Shac for almost all the details
you need. Remember that an AOA is NOT a wind-angle indicator, but a
reserve-lift indicator. So bury a little weight in the tail of your wind
vane.
Your Mileage May Vary...........
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) 764-2072
Email: emjones@charter.net
"Everything you've learned in school as "obvious" becomes less and less
obvious
as you begin to study the universe. For example, there are no solids in
the
universe. There's not even a suggestion of a solid. There are no absolute
continuums. There are no surfaces. There are no straight lines."
- R. Buckminster Fuller
Message 2
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| Subject: | Dimming of UMA EL Light Strip |
--> AeroElectric-List message posted by: Yabergs4@aol.com
I am running a solid state dimming system sold through B&C, and have hooked
up a UMA EL light strip. The instructions indicate to dim the primary current
(14V) before the converter (switching DC to AC power). Everything works
properly, but the EL strip does not dim at the same rate as the panel lights and
is
to bright while the panel is to dim.
Does anybody have a simple fix, my thinking is to put some kind of
resister in front of the converter to "pre dim" the strip, which is being use to
cast a low glow on my toggle switches.
If that is not an option does any body know of a stand alone rheostat that is
made for small applications unlike the one sold by spruce.
Thanks for any advise, Tom Yaberg (an Electronic novice)....... Camarillo,
CA.
Message 3
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| Subject: | RE: LED position lights. |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
The Whelen 70875 position lights are really cool---From the photos of the
part here is what I can tell (my guess). Thanks Whelen for taking the
plunge.
Diagnosis--The LEDs are likely to be seven pieces of LXHL-PM02 Luxeon
Emitter V Green Lambertian 120 lumens 150 degrees 6.84V and 700 mA or their
red equivalent. Whelen says if one LED is out it must be replaced, so they
are out on the spec-edge.
Now for the arrangement. They run this thing only at 28V and 0.35 Amps (
10W ). Since the published current (350 mA) is less than the current of a
single led (700 mA), they must boost the voltage to 56V (!). This may be a
forward-looking design for the coming 42.2V cars and 56V aircraft...I don't
know.) So they run 7 lamps in series. Wild....Is there something I'm missing
here??????
Now for the photometry. How do they get the 2 candelas pointing up and down.
Is this scattered from the polycarb? Whelen may have tweaked custom molded
methacrylate aspheres to cover this area.
Price: Someone will post it later (I write this Saturday evening). Rob
Housman reported that Whelan charges $428.95 for their LED tail light. The
Luxeons Emitter V's cost retail $40 each or $280 for the set and maybe $150
for the other parts. That's $430 just for parts (!) Add your own profit
margin but my guess is Whelen struggled to price it just under a Federal
Reserve Note with a picture of Grover Cleveland on it. EACH.
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) 764-2072
Email: emjones@charter.net
In theory there is no difference between theory and practice. In practice
there is.
--Yogi Berra
Message 4
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--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
I have been reading this thread and unfortunately the force to accurately
measure near stall airspeed for example 40MPH to a relative airflow accuracy
of 2 deg requires a pot with a friction force perhaps 100 times less than
the suggested pot. What is needed is a servo mount ballbearing shaft style
pot. Conventional pots simply will not work with a reasonable sized vane
setup. The torque required is way too high and this results in a huge
deadband (ERROR).
The vane needs to be designed carefully and slightly forward balanced to
avoid flutter. The vane wing design is tricky as well to avoid slight
flutter or hunting.
I have designed both servopot and air pressure AOA setups with both simple
(NSC chip bar dislpay) and complex electronics (PIC micro with audio
warnings etc) including auto dimming of the display. Both designs have been
flight tested. HP makes super bright wide angle leds in several colors that
are truely wide and full sun readable and easily dimmed to night use.
A simple design will be put in public domain some time early next year. No
details available at present.
However, remember you are looking at an active angle range under 20 deg
(full stall to max airspeed) and need <0.1 oz in torque max even at 40 MPH.
The subject pot is around 2.0 and its better if the torque is around 0.01 or
less. Shielded pots are available but so far I cannot find any sealed pots
with low torque. All must be ball bearing to even be close to being
suitable.
Paul
----- Original Message -----
From: "Eric M. Jones" <emjones@charter.net>
Subject: AeroElectric-List: AOA
> --> AeroElectric-List message posted by: "Eric M. Jones"
<emjones@charter.net>
>
> >--> AeroElectric-List message posted by: Sigma Eta Aero
> <sigmatero@yahoo.com>
>
> >This little bugger looks about perfect for the job and seems to be priced
> pretty
> >well. Since output is a function of input wouldn't you have to supply a
> regulated
> >and constant 5.0VDC to it and if so what is the easiest way to accomplish
> >this?
>
> >Joa
>
> Plan on using the stock part HRS100SSAB90. You should be able to get one
> from www.potentiometers.com
>
> The part is ratiometric, which means it puts out 4.8V at some angle with
> 5.0Vcc input. But if the input sags to 90% of what it was, then the output
> is 90% of what it was. A designer can use this fact to allow the use of no
V
> regulators.
>
> Buy Forrest Mims' engineers notebook at Rad Shac for almost all the
details
> you need. Remember that an AOA is NOT a wind-angle indicator, but a
> reserve-lift indicator. So bury a little weight in the tail of your wind
> vane.
>
> Your Mileage May Vary...........
>
> Regards,
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge MA 01550-2705
> Phone (508) 764-2072
> Email: emjones@charter.net
>
> "Everything you've learned in school as "obvious" becomes less and less
> obvious
> as you begin to study the universe. For example, there are no solids in
> the
> universe. There's not even a suggestion of a solid. There are no
absolute
> continuums. There are no surfaces. There are no straight lines."
> - R. Buckminster Fuller
>
>
Message 5
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| Subject: | Re: Dimming of UMA EL Light Strip |
--> AeroElectric-List message posted by: Tammy and Mike Salzman <arrow54t@yahoo.com>
--- Yabergs4@aol.com wrote:
> --> AeroElectric-List message posted by: Yabergs4@aol.com
> Everything works
> properly, but the EL strip does not dim at the same rate as the panel
> lights and is
> to bright while the panel is to dim.
I would try using a separate dimmer (rheostat only) for the UMA
inverter. UMA has one available it is part number 1G01. I think any
correctly sized rheostat would suffice.
Good luck,
Mike Salzman
Lancair ES
Fairfield, CA
Message 6
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--> AeroElectric-List message posted by: william mills <courierboy@earthlink.net>
Hi Paul -
I followed your original design and development efforts for an AOA
system on the Kitfoxlist a few years back, and I know it is now being
marketed commercially and is flying in a number of planes.
I appreciate the work you've done in bringing this instrumentation to
the little guys. I knew I was right to hold off on buying one a
little longer - I'll be watching ;-)
I wish you all the best - and thank you again.
Bill Mills
RANS Courier/912uls
covering
SF bay area CA.
do not archive
>--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
>
>I have been reading this thread and unfortunately the force to accurately
>measure near stall airspeed for example 40MPH to a relative airflow accuracy
>of 2 deg requires a pot with a friction force perhaps 100 times less than
>the suggested pot. What is needed is a servo mount ballbearing shaft style
>pot. Conventional pots simply will not work with a reasonable sized vane
>setup. The torque required is way too high and this results in a huge
>deadband (ERROR).
>
>The vane needs to be designed carefully and slightly forward balanced to
>avoid flutter. The vane wing design is tricky as well to avoid slight
>flutter or hunting.
>
>I have designed both servopot and air pressure AOA setups with both simple
>(NSC chip bar dislpay) and complex electronics (PIC micro with audio
>warnings etc) including auto dimming of the display. Both designs have been
>flight tested. HP makes super bright wide angle leds in several colors that
>are truely wide and full sun readable and easily dimmed to night use.
>
>A simple design will be put in public domain some time early next year. No
>details available at present.
>
>However, remember you are looking at an active angle range under 20 deg
>(full stall to max airspeed) and need <0.1 oz in torque max even at 40 MPH.
>The subject pot is around 2.0 and its better if the torque is around 0.01 or
>less. Shielded pots are available but so far I cannot find any sealed pots
>with low torque. All must be ball bearing to even be close to being
>suitable.
>
>Paul
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