Building an electronic Angle of Attack indicator

"Barnyard BOb" wrote in message
...


And after all is said and done, we remind ourselves that we are supposed
to be building inexpensive airplanes that look good and fly well.

Which is a valid reason to step back from AOA and just build a better
basic
stall warning.

Vaughn

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

AMEN.

First learn to fly with competency and K.I.S.S. in mind.

If you fly honest inexpensive safe machines and you're and honest
pilot, you can grow old without a gadget to stare at whist you forget
to fly the plane to an untimely demise. :-)

Barnyard BOb - 55 years of licensed powered flight w/o AOA


And another F'ing a Bubba.

If you can't fly your aircraft well enough to shoot safe approaches without
an AIR SPEED indicator, you need to surrender your ticket and go back in to
training. Much less an angle of attack indicator.

That's just what we need, more **** to keep your head INSIDE the airplane.
What next, satellite TV?

Ed wrote:

Some years back there was a complete description of a thermistor based
system in Sport Aviation. You might contact the research department or
whatever they call it.

I recall reading details of a thermistor sensor autopilot system years ago.
A little air pump blew a small jet towards an array of four thermistors
in a box. If the aircraft pitched, then the jet was deflected more
towards one thermistor than its opposite. Both thermistors went to an op
amp. Another pair of thermistors were responsive to yaw rate and turn.

Such a neat conception! I talked to him on the phone. He worked
(works) for a NASA lab - Ames, if I recall. Still have the article
somewhere.

Brian W

Hey, Dan, you are posting in rec.aviation HOMEBUILT. I appreciate your
expertise, but your bias towards keeping large jet aircraft running is
showing. Have you BUILT a homebuilt:? Have you MAINTAINED a single engine
aircraft?

With all due respects, sir, if you have not, please refrain from those of us
who have.

Jim



"Dan" wrote in message
...
Every aircraft synchro I have ever seen uses 26 VAC 400 hz single phase.
I have seen power supplies for them on e-bay for around $25 or so. It's
been awhile since I have looked, but they were there. In any event synchro
systems don't seem to be sine wave particular so a simple power supply
should be easy.

If you want cheap aircraft synchros find a shop that repairs jet
aircraft. The 1" "peanut" pressure indicators contain a synchro that
usually outlasts the internal lighting. I have found them on e-bay also.
Compass amplifiers such as used in the C-12 compass system contain a
multitude of synchros since they use a gear train to drive several
synchros. Vertical scale instruments such as those used on C-141 also
contain synchros. I have seen those for sale on e-bay also.

Dan, U.S. Air Force, retired

The electronics are trivial. The sensors are everything. Please post
detailed information.

Jim



"Rip" wrote in message
...


My pleasure. This topic is timely, since I recently built myself a
"Lift Reserve Indicator" based on the LM3914 and a Honeywell sensor.
Now I'm doing a "true" angle of attack indicator based on the Maxim
4210 multiplier (and an op amp) to correct for airspeed ram pressure.

A terrific treatise on the subject (with one inconsequential math error)
can be found he
http://users.cablemo.net/~jjshultz/sonex/aoa.html

Rip

That was "ElectrRO Fluidic Autopilot and my good friend Doug Garner from
NASA Langley wrote it. I haven't heard from him in some years, but he was
damn near 80 the last time I saw him at Oshkosh 20 years ago.

Jim




"cavelamb" wrote in message
m...
Ed wrote:


Some years back there was a complete discription of a thermistor based
system in Sport Aviation. You might contact the research department or
whatever they call it.

Might refer to "Electo Fluidic Autopilot" article.

NASA Langley. Doug Garner. Several published articles in Sport Aviation.
cf Fluidic Autopilot.

Jim
"Brian Whatcott" wrote in message
...
Ed wrote:

Some years back there was a complete description of a thermistor based
system in Sport Aviation. You might contact the research department or
whatever they call it.

I recall reading details of a thermistor sensor autopilot system years
ago.
A little air pump blew a small jet towards an array of four thermistors
in a box. If the aircraft pitched, then the jet was deflected more towards
one thermistor than its opposite. Both thermistors went to an op amp.
Another pair of thermistors were responsive to yaw rate and turn.

Such a neat conception! I talked to him on the phone. He worked
(works) for a NASA lab - Ames, if I recall. Still have the article
somewhere.

Brian W

RST Engineering - JIm wrote:
Hey, Dan, you are posting in rec.aviation HOMEBUILT. I appreciate your
expertise, but your bias towards keeping large jet aircraft running is
showing. Have you BUILT a homebuilt:? Have you MAINTAINED a single engine
aircraft?

With all due respects, sir, if you have not, please refrain from those of us
who have.

Jim

Have you not seen synchro repeaters driven by vacuum gyros as used
in home built/ GA aircraft? Heading hold, perhaps? The little 26 VAC
inverter I mentioned is for synchro excitation for such systems. I have
two of them around here somehwere. Neither are mil-spec or STCed or home
made.

As for "large jet aircraft" bias the biggest I ever worked on was
C-141, the smallest was a Cessna 172. You can guess who owned the former
and the owner of the later has probably died of old age by now. I wasn't
aware O-2 would be considered "large jet aircraft" and I have experience
on recips. Most of my experience is on turboshafts or turboprops, this
doesn't make my ideas any less valid than yours.


I have never built a home built, but I have assisted and made several
sub-assemblies including instrument panels.

None of the synchro systems I ever used took 3 phase in. Transmitter
and motors both use single phase for excitation. Perhaps you'd care to
tell us what what Boeing/ USAF aircraft used 115 VAC 400 hz 3 phase power.

I suggested sources for synchros for you or anyone who might want to
play with them. If you don't want to try them, fine, maybe someone else
might.

As for refraining it's not your place to suggest I do anything of the
sort. This isn't a contest between us.

Dan, U.S. Air Force, retired

RST Engineering - JIm wrote:
The electronics are trivial. The sensors are everything. Please post
detailed information.

Jim



"Rip" wrote in message
...


My pleasure. This topic is timely, since I recently built myself a
"Lift Reserve Indicator" based on the LM3914 and a Honeywell sensor.
Now I'm doing a "true" angle of attack indicator based on the Maxim
4210 multiplier (and an op amp) to correct for airspeed ram pressure.

A terrific treatise on the subject (with one inconsequential math error)
can be found he
http://users.cablemo.net/~jjshultz/sonex/aoa.html

Rip


I used a Honeywell ASDXL05D44D on my initial "lift reserve indicator",
mainly be cause I had a spare kicking around.

The true angle of attack design uses 2 Freescale MPXV7002 sensors.

The sensors really aren't that critical.You're after a repeatable
differential pressure signal, rather than absolute accuracy.

Rip wrote:
RST Engineering - JIm wrote:
The electronics are trivial. The sensors are everything. Please post
detailed information.

Jim



"Rip" wrote in message
...


My pleasure. This topic is timely, since I recently built myself a
"Lift Reserve Indicator" based on the LM3914 and a Honeywell sensor.
Now I'm doing a "true" angle of attack indicator based on the Maxim
4210 multiplier (and an op amp) to correct for airspeed ram pressure.

A terrific treatise on the subject (with one inconsequential math
error) can be found he
http://users.cablemo.net/~jjshultz/sonex/aoa.html

Rip


I used a Honeywell ASDXL05D44D on my initial "lift reserve indicator",
mainly be cause I had a spare kicking around.

The true angle of attack design uses 2 Freescale MPXV7002 sensors.

The sensors really aren't that critical.You're after a repeatable
differential pressure signal, rather than absolute accuracy.


I forget who makes it, but there's a commercially available system
that uses ports in the leading edge of a wing. My primary concern would
be how one protects from fouling while parked. I like your probe idea
since one could easily make a protective sleeve with a "remove before
flight" streamer attached.

Dan, U.S. Air Force, retired

On Sat, 9 May 2009 05:30:37 -0700 (PDT), Mike
wrote:

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.
Buy an electronic differential pressureindicator and put a bar graph
on it.

Not cheap - new Setras are about $400 but they are available surplus
occaisionally at good prices. You want 0-5 volt, not 20ma outputs.