Glider angle of attack indicator by SafeFlight

When dealing with AoA sensors it is very important to consider how it
is to be used. If it is intended to be a Go - NoGo stall warning
device, that is one thing. If it is intended to be used to measure
and be proportional to a range of AoA that is quite another. The
mounting becomes quite critical because the airflow may be such that 1
degree of AoA change does not translate into 1 degree of sensor
movement (in the case of a vane for example) . As a young flight
control engineer I learned this the hard way when an AoA vane mounted
near the nose of a test vehicle actually changed 5 degrees for every
degree of AoA change of the aircraft.

Greg

"gfoster07k" wrote in message
...
When dealing with AoA sensors it is very important to consider how it
is to be used. If it is intended to be a Go - NoGo stall warning
device, that is one thing. If it is intended to be used to measure
and be proportional to a range of AoA that is quite another. The
mounting becomes quite critical because the airflow may be such that 1
degree of AoA change does not translate into 1 degree of sensor
movement (in the case of a vane for example) . As a young flight
control engineer I learned this the hard way when an AoA vane mounted
near the nose of a test vehicle actually changed 5 degrees for every
degree of AoA change of the aircraft.

Greg

Good point.

Lets say that you will be interested in only stall, min sink, and best L/D
at each flap setting. Can it be calibrated for that?

Bill Daniels

Hi Bill,

It is a very interesting device. I looked at it very closely at the SSA
Convention in the past. I was impressed with the high quality of the
system. If I remember correctly it includes a low friction rotating vane
that is mounted to the side of the fuselage and a variometer like meter that
is mounted in the instrument panel. I don't recall whether or not it had an
audio output. It looked very cool. I don't remember the price, but I do
remember thinking that very few glider pilots would pay the somewhat high
price. Also, it required a hole in the side of the fuselage.

Paul Remde


"Bill Daniels" bildan@comcast-dot-net wrote in message
. ..
I was very pleased to see the advert in the December issue of "Soaring
Magazine".
See: www.safeflight.com

Does anybody know more about this device - especially the price?

Bill Daniels

Cost and installation issues are a real hurdle as is just how well the
device performs in actual use.

However, we seem to pay large sums for safety devices like transponders and
ELT's when it is at least argueable that stall/spin accidents kill far more
pilots than mid-airs or exposure after a landout. It's possible that on a
"bang for the buck" basis, an AOA indicator is a better deal. This is
especially true if the AOA indicator actually improves our soaring
performance while increasing safety.

It's even possible to argue that one offsets the other. i.e. If your AOA
indicator prevents a spin in on the ridge, you have avoided, at least in
that instance, the need for an ELT, saved your glider and maybe yourself in
the bargan.

I can't think of any device that would have more impact on accident numbers
than a really practical AOA indicator.

Bill Daniels


"Paul Remde" wrote in message
news:aPg6j.222593$Xa3.195325@attbi_s22...
Hi Bill,

It is a very interesting device. I looked at it very closely at the SSA
Convention in the past. I was impressed with the high quality of the
system. If I remember correctly it includes a low friction rotating vane
that is mounted to the side of the fuselage and a variometer like meter
that is mounted in the instrument panel. I don't recall whether or not it
had an audio output. It looked very cool. I don't remember the price,
but I do remember thinking that very few glider pilots would pay the
somewhat high price. Also, it required a hole in the side of the
fuselage.

Paul Remde


"Bill Daniels" bildan@comcast-dot-net wrote in message
. ..
I was very pleased to see the advert in the December issue of "Soaring
Magazine".
See: www.safeflight.com

Does anybody know more about this device - especially the price?

Bill Daniels

On Dec 7, 12:53 pm, "Bill Daniels" bildan@comcast-dot-net wrote:

I can't think of any device that would have more impact on accident numbers
than a really practical AOA indicator.

Bill, I think you have presented a case for the benefit of an
effective stall warning system but not necessarily a good case for an
AOA indicator. Unless the AOA sensor is linked to an effective
warning system it is more likely to be an added distraction rather
than a benefit.

Now if someone took that sensor and used it to drive an audio
thermalling speed director I could get interested.

Andy

Bill Daniels wrote:
Cost and installation issues are a real hurdle as is just how well the
device performs in actual use.

However, we seem to pay large sums for safety devices like transponders and
ELT's when it is at least argueable that stall/spin accidents kill far more
pilots than mid-airs or exposure after a landout. It's possible that on a
"bang for the buck" basis, an AOA indicator is a better deal. This is
especially true if the AOA indicator actually improves our soaring
performance while increasing safety.

It's even possible to argue that one offsets the other. i.e. If your AOA
indicator prevents a spin in on the ridge, you have avoided, at least in
that instance, the need for an ELT, saved your glider and maybe yourself in
the bargan.

I can't think of any device that would have more impact on accident numbers
than a really practical AOA indicator.

I wonder if a stall warning is more complicated than an effective AOA
indicator mounted on or near the fuselage. Sure, it'd work for straight
ahead stalls, but how often do those cause accidents, compared to stalls
while turning? My experience in stall/spins while turning is the root
isn't stalled, it's the outer wing portions (likely from the tip inward
for a few feet) that stalls and precipitates the spin.

And perhaps we are chasing the wrong parameter. Separation of the
airflow is a better indicator of a stall in progress; in fact, I think
Johnson's indicator worked by detecting separation, not AOA. This might
work without the need for sensing flap position, simplifying things.

One way to detect separation would be to flush-mount a microphone out
near the tip of each wing, positioned on the chord where separation
begins as that section gets near stall. The cockpit indicator might just
be the signal from the microphone, amplified and fed to a speaker. LEDs
could be used instead or in addition to the sound, of course.

The microphone could be very small, and a small tube (say, 0.1"
diameter) could lead the sound from the wing surface, through the wing
skins, to the microphone. A thin membrane covering the outer end of the
tube would prevent water and dirt from affecting performance.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Bill,
I think what we are after is an effective angle of attack indicator to
optimize performance for a rage of flap settings that will also
coincidently act as a stall warning.
Udo


On Dec 7, 2:53 pm, "Bill Daniels" bildan@comcast-dot-net wrote:
Cost and installation issues are a real hurdle as is just how well the
device performs in actual use.

However, we seem to pay large sums for safety devices like transponders and
ELT's when it is at least argueable that stall/spin accidents kill far more
pilots than mid-airs or exposure after a landout. It's possible that on a
"bang for the buck" basis, an AOA indicator is a better deal. This is
especially true if the AOA indicator actually improves our soaring
performance while increasing safety.

It's even possible to argue that one offsets the other. i.e. If your AOA
indicator prevents a spin in on the ridge, you have avoided, at least in
that instance, the need for an ELT, saved your glider and maybe yourself in
the bargan.

I can't think of any device that would have more impact on accident numbers
than a really practical AOA indicator.

Bill Daniels

"Paul Remde" wrote in message

news:aPg6j.222593$Xa3.195325@attbi_s22...



Hi Bill,

It is a very interesting device. I looked at it very closely at the SSA
Convention in the past. I was impressed with the high quality of the
system. If I remember correctly it includes a low friction rotating vane
that is mounted to the side of the fuselage and a variometer like meter
that is mounted in the instrument panel. I don't recall whether or not it
had an audio output. It looked very cool. I don't remember the price,
but I do remember thinking that very few glider pilots would pay the
somewhat high price. Also, it required a hole in the side of the
fuselage.

Paul Remde

"Bill Daniels" bildan@comcast-dot-net wrote in message
...
I was very pleased to see the advert in the December issue of "Soaring
Magazine".
See:www.safeflight.com

Does anybody know more about this device - especially the price?

Bill Daniels- Hide quoted text -

- Show quoted text -

Udo, absolutely.

A mere stall warner is just a "stall" or "no stall" binary device. An AOA
indicator, by comparison, gives stall margin or how close you are to a stall
as well as the rate at which you are approaching it. Of course, stall
warning is a part of that.

It also is a performance device that lets the pilot optimize flight. You
can change AOA with the elevator with almost no delay. Airspeed needs more
time to change. Thermalling at a constant, optimum AOA is easy and the
airspeed will be much steadier. The optimum AOA is the same regardless of
wing loading or bank angle.

Unless you have flown with an AOA indicator, it's hard to imagine what it
does. I've never head someone who has used one say they didn' t like it.

Bill Daniels

"Udo" wrote in message
...
Bill,
I think what we are after is an effective angle of attack indicator to
optimize performance for a rage of flap settings that will also
coincidently act as a stall warning.
Udo


On Dec 7, 2:53 pm, "Bill Daniels" bildan@comcast-dot-net wrote:
Cost and installation issues are a real hurdle as is just how well the
device performs in actual use.

However, we seem to pay large sums for safety devices like transponders
and
ELT's when it is at least argueable that stall/spin accidents kill far
more
pilots than mid-airs or exposure after a landout. It's possible that on
a
"bang for the buck" basis, an AOA indicator is a better deal. This is
especially true if the AOA indicator actually improves our soaring
performance while increasing safety.

It's even possible to argue that one offsets the other. i.e. If your AOA
indicator prevents a spin in on the ridge, you have avoided, at least in
that instance, the need for an ELT, saved your glider and maybe yourself
in
the bargan.

I can't think of any device that would have more impact on accident
numbers
than a really practical AOA indicator.

Bill Daniels

"Paul Remde" wrote in message

news:aPg6j.222593$Xa3.195325@attbi_s22...



Hi Bill,

It is a very interesting device. I looked at it very closely at the
SSA
Convention in the past. I was impressed with the high quality of the
system. If I remember correctly it includes a low friction rotating
vane
that is mounted to the side of the fuselage and a variometer like meter
that is mounted in the instrument panel. I don't recall whether or not
it
had an audio output. It looked very cool. I don't remember the price,
but I do remember thinking that very few glider pilots would pay the
somewhat high price. Also, it required a hole in the side of the
fuselage.

Paul Remde

"Bill Daniels" bildan@comcast-dot-net wrote in message
...
I was very pleased to see the advert in the December issue of "Soaring
Magazine".
See:www.safeflight.com

Does anybody know more about this device - especially the price?

Bill Daniels- Hide quoted text -

- Show quoted text -

On Dec 7, 3:36 pm, "Bill Daniels" bildan@comcast-dot-net wrote:

Unless you have flown with an AOA indicator, it's hard to imagine what it
does. I've never head someone who has used one say they didn' t like it.


Agreed. I last flew with an AOA indicator just a few weeks ago but it
was included in a HUD symbology set, not head down. The last thing we
need is for all contest pilots to have a head down indicator that they
depend on to optimize performance while thermalling.

Make it a director, feed it flap position (if applicable) and make it
audible!

Andy

Look at Aircraft Spruce and Specialty, angle of attack indicators.
Three different versions. Costly, but seems to have all that you guys
are talking about.

We have one in the 737-800 I fly, and never use it unless "heads
down." Captain has HUD with AOA symbology, speed vector and VSI, along
with a bunch of other crap, thats what we need, a HUD.
Justin Rizor