Building an electronic Angle of Attack indicator

Has anyone built an electronic angle of attack meter kit. It seems to
be something that would be easy to design but beyond my feeble
electronics background.

I have seen the products that are out there and they are simple
differential pressure gauges and are expensive. I don't like the
round differential pressure gauges that many of the companies offer
for this kind of system. I was wondering if there would be a way to
put something together that would light up different color LED's for
the different levels of lift that we could build at home without
having to pay out hundreds of dollars for a prebuilt one.

If somebody can tell me how to convert angle of attack to an electrical
signal, the rest is rather trivial.

Jim


"Mike" wrote in message
...
Has anyone built an electronic angle of attack meter kit. It seems to
be something that would be easy to design but beyond my feeble
electronics background.

I have seen the products that are out there and they are simple
differential pressure gauges and are expensive. I don't like the
round differential pressure gauges that many of the companies offer
for this kind of system. I was wondering if there would be a way to
put something together that would light up different color LED's for
the different levels of lift that we could build at home without
having to pay out hundreds of dollars for a prebuilt one.

RST Engineering - JIm wrote:
If somebody can tell me how to convert angle of attack to an electrical
signal, the rest is rather trivial.

Jim


"Mike" wrote in message
...
Has anyone built an electronic angle of attack meter kit. It seems to
be something that would be easy to design but beyond my feeble
electronics background.

I have seen the products that are out there and they are simple
differential pressure gauges and are expensive. I don't like the
round differential pressure gauges that many of the companies offer
for this kind of system. I was wondering if there would be a way to
put something together that would light up different color LED's for
the different levels of lift that we could build at home without
having to pay out hundreds of dollars for a prebuilt one.



Use variable capacitance, variable reluctance, resistor strip or
synchro connected to a vane. For a real giggle do as some Air Force
systems and employ a slotted, rotating cone for a probe. It involves a
feedback loop.

Dan, U.S. Air Force, retired

Those might get me airspeed but I'm not at all sure how you would get theta
from any one of these schemes.

Jim


Use variable capacitance, variable reluctance, resistor strip or
synchro connected to a vane. For a real giggle do as some Air Force
systems and employ a slotted, rotating cone for a probe. It involves a
feedback loop.

Dan, U.S. Air Force, retired

"RST Engineering - JIm" wrote:
Those might get me airspeed but I'm not at all sure how you would get
theta from any one of these schemes.

I believe he means the vane is lightweight and freely pivots up or down so
that it is always pointing into the relative wind. The angle the vane makes
with some reference line on the wing or fuselage is thus the AoA. I'd post
a link to a picture of what it would look like (pretty simple concept) but
can't see to find one!

Just think of the yaw string on gliders (e.g. the red string in this
pictu http://www.highonadventure.com/Hoa08...eYawString.jpg)
but used to show vertical component of the relative wind, not horizontal.

Use variable capacitance, variable reluctance, resistor strip or
synchro connected to a vane. For a real giggle do as some Air Force
systems and employ a slotted, rotating cone for a probe. It involves
a feedback loop.

Dan, U.S. Air Force, retired

Jim Logajan wrote:
I'd post a link to a picture of what it would look like
(pretty simple concept) but can't see to find one!

Okay, found some, like this one:
http://commons.wikimedia.org/wiki/Fi...ndicator_1.jpg

And a simple mechanical kit (looks like no longer available):
http://www.aircraftspruce.com/catalo...baconsaver.php

My suspicion is that designers get fancy and use things like two non-
parallel pitots and use some mechanism to compute the AoA from their
differential pressures, which is then presented in some fancy digital
display. The irony is that AoA is easy to show, and if one is flying a
glider or pusher, a simple mechanical device could probably be mounted so
it is visible out front (i.e. "heads up") so that one can see the AoA at
the same time one is controlling their approach. But I suppose it'd be too
distracting during crusing flight and mess up the "look" of the airplane.


Just think of the yaw string on gliders (e.g. the red string in this
pictu
http://www.highonadventure.com/Hoa08...eYawString.jpg) but
used to show vertical component of the relative wind, not horizontal.

Use variable capacitance, variable reluctance, resistor strip or
synchro connected to a vane. For a real giggle do as some Air Force
systems and employ a slotted, rotating cone for a probe. It involves
a feedback loop.

Dan, U.S. Air Force, retired

RST Engineering - JIm wrote:
If somebody can tell me how to convert angle of attack to an electrical
signal, the rest is rather trivial.

Jim


"Mike" wrote in message
...

Has anyone built an electronic angle of attack meter kit. It seems to
be something that would be easy to design but beyond my feeble
electronics background.

I have seen the products that are out there and they are simple
differential pressure gauges and are expensive. I don't like the
round differential pressure gauges that many of the companies offer
for this kind of system. I was wondering if there would be a way to
put something together that would light up different color LED's for
the different levels of lift that we could build at home without
having to pay out hundreds of dollars for a prebuilt one.




We used a reed switch array and a magnet to determine control rod position on my submarine's reactor. You could do the same with an
AOA using a magnet on a vane. You'd only need a few reed switches, one for each angle you were interested in: just before stall, best
angle of climb and best rate of climb corresponding to red, yellow and green LED's. What else do you care about?

--
John Kimmel


I think it will be quiet around here now. So long.

Heck, my first thought was to take the gas gage & sendin unit out of my
'56 chevy , mount the sendin unit inside with some gears outa of my old
alarm clock-(spring busted) sos you get full travel outa the sender with
only ten or 20 degrees motion hang a n aluminium vane on the end of it &
a fishin sinker forward of it to balance it-You could keep the sinker
inside for essthetic reasons. ut then---this was jest my 1st thot--Jerry

RST Engineering - JIm wrote:
If somebody can tell me how to convert angle of attack to an
electrical signal, the rest is rather trivial.

Jim


"Mike" wrote in message
...

Has anyone built an electronic angle of attack meter kit. It seems to
be something that would be easy to design but beyond my feeble
electronics background.

I have seen the products that are out there and they are simple
differential pressure gauges and are expensive. I don't like the
round differential pressure gauges that many of the companies offer
for this kind of system. I was wondering if there would be a way to
put something together that would light up different color LED's for
the different levels of lift that we could build at home without
having to pay out hundreds of dollars for a prebuilt one.




We used a reed switch array and a magnet to determine control rod
position on my submarine's reactor. You could do the same with an AOA
using a magnet on a vane. You'd only need a few reed switches, one for
each angle you were interested in: just before stall, best angle of
climb and best rate of climb corresponding to red, yellow and green
LED's. What else do you care about?

RST Engineering - JIm wrote:
Those might get me airspeed but I'm not at all sure how you would get theta
from any one of these schemes.

Jim


Use variable capacitance, variable reluctance, resistor strip or
synchro connected to a vane. For a real giggle do as some Air Force
systems and employ a slotted, rotating cone for a probe. It involves a
feedback loop.

Dan, U.S. Air Force, retired



The vane types are self explanatory.

http://www.aircraftmech.com/pics/aoa.jpg

http://spaceagecontrol.com/4239-01image.jpg

The cone type is a bit more complicated. Picture a hollow stainless
cone with two sets of slots running between base and apex. The slots
face towards the front of the airplane. Each set opens to its own
chamber in the cone. The pressure in each chamber is measured and the
cone is rotated until the pressures are equal. The position is then
transmitted to an indicator.

http://www.avionics-specialties.com/...thumb_stat.jpg

The cone types are usually heated to prevent icing.

If I were to build one for small aircraft I'd go with a vane and
resistance strip. In that case a standard d'arsonval meter or column of
LEDs could be used to indicate AOL.

Pressure differential systems have the disadvantages of icing or dirt
contamination.

Dan, U.S. Air Force, retired

Jerry Wass wrote:
Heck, my first thought was to take the gas gage & sendin unit out of my
'56 chevy , mount the sendin unit inside with some gears outa of my old
alarm clock-(spring busted) sos you get full travel outa the sender with
only ten or 20 degrees motion hang a n aluminium vane on the end of it &
a fishin sinker forward of it to balance it-You could keep the sinker
inside for essthetic reasons. ut then---this was jest my 1st thot--Jerry


That's essentially how a vane type works.

Dan, U.S. Air Force, retired