no instrument flight

"Don Johnstone" wrote in message
...
At 06:42 08 July 2006, G L I D E R S T U D wrote:

Yaw sting....if you cant feel your body sliding left
or right when your
uncoordinated, you should probably relax some, because
you are way too
uptight. But then again one of my coaches said I was
too relaxed. On
that note my Discus 2ax didn't have a yaw sting, and
my Nimbus 3
doesn't have one either, and I probably won't get it
'fixed' before the
Opens. I fly in the mountains and I don't feel that
it is hazardous.
Plus that sting is way too much drag.

I defy anyone to 'feel' the tiny amount of yaw that
a yaw string will indicate. The drag created by even
the largest piece of wool will be very small compared
to even a small amout of yaw in straight and level
flight. A 'T&S' ball is just not sensitive enough and
the yaw string has the advantage of being in your eye
line, you don't have to go heads down to see it. To
fly efficiently in a big winged glider is is even more
essential as even tiny amoutns of control differences
are magnified with the addition leverage of long wings.


To Don Johnstone - Yep!

The weather is doing something it hasn't done in quite a while - raining -
therefore, I'm spending the weekend indoors. This has led me to research a
few ideas that I had set aside. One of them is an angle of attack indicator
for gliders.

Any reading of accident reports will quickly lead one to the conclusion that
pilots don't pay enough attention to AOA. No matter how hard AOA is
hammered into a students brain, a few months after their checkride, they
just watch the ASI. Some of them are involved in stall/spin accidents.

AOA indicators have long been essential to the safe operation of large
aircraft so, now that electronics are cheap, why not gliders too? Gliders
spend a lot of time flying near the stall AOA so we shoud be especially
interested in an AOA indicator.

So, how do we measure AOA? The traditional nose boom pitch vane is too
fragile for gliders but there is another way to get AOA data. Companies
like Masi make a simple AOA probes. See:
http://www.cgmasi.com/aviation/index.html

The Masi probe computes AOA from the pressure difference between two
pressure ports at 45 degrees to the airflow. Could the same be done with
pressure ports located on upper and lower nose? I think so. An inexpensive
differential pressure sensor and a bit of electronics driving an LED
lightbar plus a calibration proceedure would do it.

The calilbration procedure would be simple since we are only interested in
three AOA's - Stall, Minimum sink, and Best L/D. These would be very
helpful when flying gliders with a wide range of wing loadings. The min
sink AOA would be particularly helpful when flying at steep bank angles.

Gliders with flaps would have to repeat the calibration procedure for each
flap setting of interest - those being approach flaps and thermalling flaps.
Flap setting would have to be sent to the AOA conputer.

Any gadgeteers out there interested in making a few bucks awhile maybe
saving a few lives?

Bill Daniels

The last thing I want is another instrument. I enjoy gliding because I
can fly by visual references and only use the instruments to glance at
occasionally.


Bill Daniels wrote:
"Don Johnstone" wrote in message
...
At 06:42 08 July 2006, G L I D E R S T U D wrote:

Yaw sting....if you cant feel your body sliding left
or right when your
uncoordinated, you should probably relax some, because
you are way too
uptight. But then again one of my coaches said I was
too relaxed. On
that note my Discus 2ax didn't have a yaw sting, and
my Nimbus 3
doesn't have one either, and I probably won't get it
'fixed' before the
Opens. I fly in the mountains and I don't feel that
it is hazardous.
Plus that sting is way too much drag.

I defy anyone to 'feel' the tiny amount of yaw that
a yaw string will indicate. The drag created by even
the largest piece of wool will be very small compared
to even a small amout of yaw in straight and level
flight. A 'T&S' ball is just not sensitive enough and
the yaw string has the advantage of being in your eye
line, you don't have to go heads down to see it. To
fly efficiently in a big winged glider is is even more
essential as even tiny amoutns of control differences
are magnified with the addition leverage of long wings.


To Don Johnstone - Yep!

The weather is doing something it hasn't done in quite a while - raining -
therefore, I'm spending the weekend indoors. This has led me to research a
few ideas that I had set aside. One of them is an angle of attack indicator
for gliders.

Any reading of accident reports will quickly lead one to the conclusion that
pilots don't pay enough attention to AOA. No matter how hard AOA is
hammered into a students brain, a few months after their checkride, they
just watch the ASI. Some of them are involved in stall/spin accidents.

AOA indicators have long been essential to the safe operation of large
aircraft so, now that electronics are cheap, why not gliders too? Gliders
spend a lot of time flying near the stall AOA so we shoud be especially
interested in an AOA indicator.

So, how do we measure AOA? The traditional nose boom pitch vane is too
fragile for gliders but there is another way to get AOA data. Companies
like Masi make a simple AOA probes. See:
http://www.cgmasi.com/aviation/index.html

The Masi probe computes AOA from the pressure difference between two
pressure ports at 45 degrees to the airflow. Could the same be done with
pressure ports located on upper and lower nose? I think so. An inexpensive
differential pressure sensor and a bit of electronics driving an LED
lightbar plus a calibration proceedure would do it.

The calilbration procedure would be simple since we are only interested in
three AOA's - Stall, Minimum sink, and Best L/D. These would be very
helpful when flying gliders with a wide range of wing loadings. The min
sink AOA would be particularly helpful when flying at steep bank angles.

Gliders with flaps would have to repeat the calibration procedure for each
flap setting of interest - those being approach flaps and thermalling flaps.
Flap setting would have to be sent to the AOA conputer.

Any gadgeteers out there interested in making a few bucks awhile maybe
saving a few lives?

Bill Daniels

On 7/9/06 11:27 AM, in article ,
"Bill Daniels" bildan@comcast-dot-net wrote:


"Don Johnstone" wrote in message
...
At 06:42 08 July 2006, G L I D E R S T U D wrote:

Yaw sting....if you cant feel your body sliding left
or right when your
uncoordinated, you should probably relax some, because
you are way too
uptight. But then again one of my coaches said I was
too relaxed. On
that note my Discus 2ax didn't have a yaw sting, and
my Nimbus 3
doesn't have one either, and I probably won't get it
'fixed' before the
Opens. I fly in the mountains and I don't feel that
it is hazardous.
Plus that sting is way too much drag.

I defy anyone to 'feel' the tiny amount of yaw that
a yaw string will indicate. The drag created by even
the largest piece of wool will be very small compared
to even a small amout of yaw in straight and level
flight. A 'T&S' ball is just not sensitive enough and
the yaw string has the advantage of being in your eye
line, you don't have to go heads down to see it. To
fly efficiently in a big winged glider is is even more
essential as even tiny amoutns of control differences
are magnified with the addition leverage of long wings.


To Don Johnstone - Yep!

The weather is doing something it hasn't done in quite a while - raining -
therefore, I'm spending the weekend indoors. This has led me to research a
few ideas that I had set aside. One of them is an angle of attack indicator
for gliders.

Any reading of accident reports will quickly lead one to the conclusion that
pilots don't pay enough attention to AOA. No matter how hard AOA is
hammered into a students brain, a few months after their checkride, they
just watch the ASI. Some of them are involved in stall/spin accidents.

AOA indicators have long been essential to the safe operation of large
aircraft so, now that electronics are cheap, why not gliders too? Gliders
spend a lot of time flying near the stall AOA so we shoud be especially
interested in an AOA indicator.

So, how do we measure AOA? The traditional nose boom pitch vane is too
fragile for gliders but there is another way to get AOA data. Companies
like Masi make a simple AOA probes. See:
http://www.cgmasi.com/aviation/index.html

The Masi probe computes AOA from the pressure difference between two
pressure ports at 45 degrees to the airflow. Could the same be done with
pressure ports located on upper and lower nose? I think so. An inexpensive
differential pressure sensor and a bit of electronics driving an LED
lightbar plus a calibration proceedure would do it.

The calilbration procedure would be simple since we are only interested in
three AOA's - Stall, Minimum sink, and Best L/D. These would be very
helpful when flying gliders with a wide range of wing loadings. The min
sink AOA would be particularly helpful when flying at steep bank angles.

Gliders with flaps would have to repeat the calibration procedure for each
flap setting of interest - those being approach flaps and thermalling flaps.
Flap setting would have to be sent to the AOA conputer.

Any gadgeteers out there interested in making a few bucks awhile maybe
saving a few lives?

Bill Daniels


Bill,

Two or three pilots at Black Forest have very inexpensive AOA indicators
installed. They have yawstrings taped to the canopy way down the sides,
adjacent to their thighs, basically at the junction of the canopy and the
frame.

They then make marks with grease pencil at the crucial airspeeds, and report
being happy as clams with it.

Haven't tried it myself. YMMV.

Bullwinkle

"Bullwinkle" wrote in message
...
On 7/9/06 11:27 AM, in article
,
"Bill Daniels" bildan@comcast-dot-net wrote:


"Don Johnstone" wrote in message
...
At 06:42 08 July 2006, G L I D E R S T U D wrote:

Yaw sting....if you cant feel your body sliding left
or right when your
uncoordinated, you should probably relax some, because
you are way too
uptight. But then again one of my coaches said I was
too relaxed. On
that note my Discus 2ax didn't have a yaw sting, and
my Nimbus 3
doesn't have one either, and I probably won't get it
'fixed' before the
Opens. I fly in the mountains and I don't feel that
it is hazardous.
Plus that sting is way too much drag.

I defy anyone to 'feel' the tiny amount of yaw that
a yaw string will indicate. The drag created by even
the largest piece of wool will be very small compared
to even a small amout of yaw in straight and level
flight. A 'T&S' ball is just not sensitive enough and
the yaw string has the advantage of being in your eye
line, you don't have to go heads down to see it. To
fly efficiently in a big winged glider is is even more
essential as even tiny amoutns of control differences
are magnified with the addition leverage of long wings.


To Don Johnstone - Yep!

The weather is doing something it hasn't done in quite a while -
raining -
therefore, I'm spending the weekend indoors. This has led me to research
a
few ideas that I had set aside. One of them is an angle of attack
indicator
for gliders.

Any reading of accident reports will quickly lead one to the conclusion
that
pilots don't pay enough attention to AOA. No matter how hard AOA is
hammered into a students brain, a few months after their checkride, they
just watch the ASI. Some of them are involved in stall/spin accidents.

AOA indicators have long been essential to the safe operation of large
aircraft so, now that electronics are cheap, why not gliders too?
Gliders
spend a lot of time flying near the stall AOA so we shoud be especially
interested in an AOA indicator.

So, how do we measure AOA? The traditional nose boom pitch vane is too
fragile for gliders but there is another way to get AOA data. Companies
like Masi make a simple AOA probes. See:
http://www.cgmasi.com/aviation/index.html

The Masi probe computes AOA from the pressure difference between two
pressure ports at 45 degrees to the airflow. Could the same be done with
pressure ports located on upper and lower nose? I think so. An
inexpensive
differential pressure sensor and a bit of electronics driving an LED
lightbar plus a calibration proceedure would do it.

The calilbration procedure would be simple since we are only interested
in
three AOA's - Stall, Minimum sink, and Best L/D. These would be very
helpful when flying gliders with a wide range of wing loadings. The min
sink AOA would be particularly helpful when flying at steep bank angles.

Gliders with flaps would have to repeat the calibration procedure for
each
flap setting of interest - those being approach flaps and thermalling
flaps.
Flap setting would have to be sent to the AOA conputer.

Any gadgeteers out there interested in making a few bucks awhile maybe
saving a few lives?

Bill Daniels


Bill,

Two or three pilots at Black Forest have very inexpensive AOA indicators
installed. They have yawstrings taped to the canopy way down the sides,
adjacent to their thighs, basically at the junction of the canopy and the
frame.

They then make marks with grease pencil at the crucial airspeeds, and
report
being happy as clams with it.

Haven't tried it myself. YMMV.

Bullwinkle


I've done that going back several years. It works fine but those darn
strings keep getting caught under the canopy frame when you close it and
some gliders don't have canopies that allow proper placement of the strings.
Also, it only works at a zero slip angle. An electronic AOA system shouldn't
cost much but, of course, it'll cost more than strings.

bildan

Bill Daniels wrote:
I've done that going back several years. It works fine but those darn
strings keep getting caught under the canopy frame when you close it and
some gliders don't have canopies that allow proper placement of the strings.
Also, it only works at a zero slip angle. An electronic AOA system shouldn't
cost much but, of course, it'll cost more than strings.

I suspect that surface ports on the top and bottom of the nose will also
only work at zero slip/skid angle. My DG-600 was factory equipped with
an AoA meter, using two cross-connected sets of surface ports on the
fuselage just above the wing roots. One set is just aft of the leading
edge, another set is about 60% aft. The meter is a modified electronic
variometer. I've never had the meter in my panel, so I don't know how
well it works. One of these days, I'm going to connect a low pressure
differential transducer between the two sets of ports, and see if I can
get any usable data.

Marc

"Marc Ramsey" wrote in message
. com...

I suspect that surface ports on the top and bottom of the nose will also
only work at zero slip/skid angle. Marc

Why would that be?

If both top and bottom ports are on the center line they should be equally
influenced by slip/skid induced crossflow. You'd just be measuring the
pressure difference between the ports not the absolute pressure.

BTW, the guys at Black Forrest with pitch strings report they give advanced
warning of lift so zooms can start a few seconds sooner. An electronic AOA
indicator should do the same. Seems an AOA indicator is both a safety
device and a performance boon.

Bill Daniels

Bill Daniels wrote:
"Marc Ramsey" wrote in message
. com...
I suspect that surface ports on the top and bottom of the nose will also
only work at zero slip/skid angle. Marc

Why would that be?

If both top and bottom ports are on the center line they should be equally
influenced by slip/skid induced crossflow. You'd just be measuring the
pressure difference between the ports not the absolute pressure.

I'm only engaging in standard usenet-style uninformed speculation, but
I'm guessing that the flow around the nose is altered such that the
pressure differential would no longer be consistent with the angle of
attack. Also, if putting two ports on the nose was adequate, why did DG
go to the trouble of putting 4 ports above the wings?

Marc

"Marc Ramsey" wrote in message
news
I'm only engaging in standard usenet-style uninformed speculation, but I'm
guessing that the flow around the nose is altered such that the pressure
differential would no longer be consistent with the angle of attack.
Also, if putting two ports on the nose was adequate, why did DG go to the
trouble of putting 4 ports above the wings?

Marc

Like you, I'm only guesssing but it might be the DG system was intended to
be a stall warner rather than an AOA indicator although I grant the
difference is small. Ports on top of the wing might sense the progression
of flow separation at the root as a stall begins.

There's a probe call the "BAT" which presets a hemesphere with a ring of
pressure ports to the airflow. A computer collects the pressure data from
each port and outputs the Alpha/Beta angles as well as turbulence data.
See: http://www.atdd.noaa.gov/Research_Pa...WEB/batweb.htm

Bullwinkle wrote:
They then make marks with grease pencil at the crucial airspeeds, and report
being happy as clams with it.

There's something I've always wondered: why are clams happy in America?

And is this happy clam a shellfish or a cult member?


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Bill Daniels wrote:
Like you, I'm only guesssing but it might be the DG system was intended to
be a stall warner rather than an AOA indicator although I grant the
difference is small. Ports on top of the wing might sense the progression
of flow separation at the root as a stall begins.

It does provide a stall warning function (not that the glider
particularly needs one), but it was also intended to be used to indicate
AoA for purposes of optimizing the flap settings. The calibration
procedure is clearly aimed at establishing both the high and low ends of
the optimal AoA range.

Marc