Building an electronic Angle of Attack indicator

On Sat, 09 May 2009 19:58:21 -0500, Brian Whatcott
wrote:

Hmmmm...for something you could sink your teeth in, Jim, how about a
chip that could be hard mounted inside - with no access to the airflow,
that would keep indicating AoA even with a 1/2 inch of ice over the
entire airframe? $20 gets you a 3-axis accelerometer, which uses
about a couple milliwatts from a 3 volt supply, and provides 300 mV per
g. [ADXL330)
I have it in mind that the arctan [g(vertical) / g(longitudinal)] gives
a useful proxy for AofA, if you process through an op amp ($3), an a/d
on a microcontroller ($25). That way, you could have it play Dixie at
the appropriate angle if you wanted? :-)
That's if a mouth organ reed in a tube from a wing LE aperture is too
low tech?
Brian W

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.




Won't indicate RELATIVE AIR FLOW, only absolute attitude - useless as
AOA or lift reserve (iminent stall) indicator.

wrote:
On Sat, 09 May 2009 19:58:21 -0500, Brian Whatcott
wrote:

Hmmmm...for something you could sink your teeth in, Jim, how about a
chip that could be hard mounted inside - with no access to the airflow,
that would keep indicating AoA even with a 1/2 inch of ice over the
entire airframe? $20 gets you a 3-axis accelerometer, which uses
about a couple milliwatts from a 3 volt supply, and provides 300 mV per
g. [ADXL330)
I have it in mind that the arctan [g(vertical) / g(longitudinal)] gives
a useful proxy for AofA, if you process through an op amp ($3), an a/d
on a microcontroller ($25). That way, you could have it play Dixie at
the appropriate angle if you wanted? :-)
That's if a mouth organ reed in a tube from a wing LE aperture is too
low tech?
Brian W

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.



Won't indicate RELATIVE AIR FLOW, only absolute attitude - useless as
AOA or lift reserve (iminent stall) indicator.


In case there are folks who can't see it: it is possible to stall out
'flat' - in fact a few WW1 era pilots did it and walked away. The air
flow is 50+ degrees to the long axis - from underneath.

Brian W