AoA keep it going!

[fred]

In my early hours of being instructed, not one went by without stall
and spin practice. They also taught me to look out of the window.
Maybe I've done a thousand or more turns before I found myself in a
spin that I did not intend to happen. I was in an HP11, over a ridge,
with a 1-26 out climbing me. "He can't do that!" With over 60 degrees
bank, I just tightened my turn by pulling back on the stick. I
increased my AoA without concern. Snap!
The ridge was spinning below my nose and getting larger very fast. My
old instincts kicked in. I was looking at the grass when I recovered.

Now, AoA is my favorite subject to teach. My God! The ignorance is
rampant. A tow pilot applied for a job. I asked him what the
approximate angle of attack was for the Super Cub wing when it
stalled. A commercial pilot raised his arm and pointed up about 40
degrees above the horizon. He went home. I was stunned.

A favorite question I use for instruction... Which wing in a turn has
the greatest angle of attack? The pilot has a 50-50 chance at the
correct guess. No matter what his answer, I ask why? I get no answer.

A problem I find is a lack of understanding of "relative wind" Is
there no hope?

I have witnessed a low altitude spin to impact. It was not nice.

Another spin to impact gave me the opportunity to ask the pilot the
question..."What makes the glider turn?
His answer:"The rudder" He was a military acadamy pilot.

We absolutly must teach and demonstrate more angle of attack
recognition and recovery. It doesant take long before you hear or
read about a stall spin fatality, Don't let your stundent go out into
the wold without being trained in ALL aspects of AoA and stall spin
recovery.Maybe the instructor should learn first.
God bless good instructors,Fearless Fred

[Ian]

On 16 Dec, 07:14, fred > wrote:

> Another spin to impact gave me the opportunity to ask the pilot the
> question..."What makes the glider turn?
> His answer:"The rudder" He was a military acadamy pilot.

I myself am amazed at how many pilots think the ailerons make the
glider turn.

Ian

[Bill Daniels]

I recall a teaching aid used to train WWII pilots. It was a simple table
top wind tunnel made of plexiglass with a "test section" about an inch wide
and 6" high. It came with various aerodynamic shaped bits of plastic that
could be used to visualize flow. There was a small exhaust fan to pull air
through the tunnel and a clever "smoke rake" made with a small electrically
heated pot and a rake made of small diameter brass tubes soldered together.
It was a simple two dimensional wind tunnel.

You put an ounce or so of kerosene in the pot and turned on the heat. After
a bit, smoke started coming out of the dozen or so rake tubes. You then
turned on the fan and neat parallel streams of smoke flowed around the shape
in the test section.

The reynolds number was all wrong but the visualization of air flow was way
more than good enough to get the idea of angle of attack across. The
airfoil shaped test bit was nearly perfect. At about 16 degrees of AOA, the
smoke streams would burble and separate from the upper surface. No one left
the demonstration unconvinced.

The thing was a little messy. To see the smoke streamers clearly you needed
to be in a dimly lit room which quickly filled with kerosene smoke. That's
probably why it isn't used much anymore. Still, I'd love to have one.
Maybe a computer program could be just as good.

The thought occurs to me that those WWII flight schools went to a lot of
trouble to teach AOA and the graduates were among the best pilots ever
trained. Maybe we should take a look at that they did to train them.

Bill Daniels


"fred" > wrote in message
...
> In my early hours of being instructed, not one went by without stall
> and spin practice. They also taught me to look out of the window.
> Maybe I've done a thousand or more turns before I found myself in a
> spin that I did not intend to happen. I was in an HP11, over a ridge,
> with a 1-26 out climbing me. "He can't do that!" With over 60 degrees
> bank, I just tightened my turn by pulling back on the stick. I
> increased my AoA without concern. Snap!
> The ridge was spinning below my nose and getting larger very fast. My
> old instincts kicked in. I was looking at the grass when I recovered.
>
> Now, AoA is my favorite subject to teach. My God! The ignorance is
> rampant. A tow pilot applied for a job. I asked him what the
> approximate angle of attack was for the Super Cub wing when it
> stalled. A commercial pilot raised his arm and pointed up about 40
> degrees above the horizon. He went home. I was stunned.
>
> A favorite question I use for instruction... Which wing in a turn has
> the greatest angle of attack? The pilot has a 50-50 chance at the
> correct guess. No matter what his answer, I ask why? I get no answer.
>
> A problem I find is a lack of understanding of "relative wind" Is
> there no hope?
>
> I have witnessed a low altitude spin to impact. It was not nice.
>
> Another spin to impact gave me the opportunity to ask the pilot the
> question..."What makes the glider turn?
> His answer:"The rudder" He was a military acadamy pilot.
>
> We absolutly must teach and demonstrate more angle of attack
> recognition and recovery. It doesant take long before you hear or
> read about a stall spin fatality, Don't let your stundent go out into
> the wold without being trained in ALL aspects of AoA and stall spin
> recovery.Maybe the instructor should learn first.
> God bless good instructors,Fearless Fred

[Ian]

On 16 Dec, 15:22, "Bill Daniels" <bildan@comcast-dot-net> wrote:

> The thing was a little messy. To see the smoke streamers clearly you needed
> to be in a dimly lit room which quickly filled with kerosene smoke. That's
> probably why it isn't used much anymore. Still, I'd love to have one.
> Maybe a computer program could be just as good.

Everyone should -in my opinion - fly a tufted glider while training.

Ian

[Bill Daniels]

"Ian" > wrote in message
...
> On 16 Dec, 15:22, "Bill Daniels" <bildan@comcast-dot-net> wrote:
>
>> The thing was a little messy. To see the smoke streamers clearly you
>> needed
>> to be in a dimly lit room which quickly filled with kerosene smoke.
>> That's
>> probably why it isn't used much anymore. Still, I'd love to have one.
>> Maybe a computer program could be just as good.
>
> Everyone should -in my opinion - fly a tufted glider while training.
>
> Ian

Tufts are good and yes, students should see them.

However, tufts show boundary layer behavior not angle of attack and
streamlines. Start with the little smoke tunnel in the classroom and then
show them the tufts in flight.

Bill Daniels

[Ian]

On 16 Dec, 23:19, "Bill Daniels" <bildan@comcast-dot-net> wrote:

> However, tufts show boundary layer behavior not angle of attack and
> streamlines. Start with the little smoke tunnel in the classroom and then
> show them the tufts in flight.

Every gliding club should have a copy of "An Album of Fluid Motion" by
Milton Van Dyke!

Ian

[Neal Pfeiffer]

Tufts are probably the best way to visualize the unsteady flow near
stall (as long as the tufts are not so large that they affect the flow.)
The tufts show when, where, and how the wing actually stalls. The
flight can be straight ahead, in a turn, with an accelerated entry, ...

The real question is, when does the wing stall and how can information
be passed to the pilot to avoid the stall?

Tufts are not a very practical method in normal operation, but they are
great during the development of a aircraft.

Airspeed has been used widely as the indirect means to avoid stall.
Airspeed is readily available on any glider and by using a relatively
simple weight and bank angle correction, one can determine a safe airspeed.

AOA vanes on the fuselage are often used on a range of powered aircraft.
On commercial ones, these are often linked electronically to a stick
pusher in the cockpit to inhibit stall.

Some small airplanes use leading-edge vanes on the inboard wing and I've
even seen a small vane on the upper aft portion of the wing on a 1947
Bonanza.

If you are concerned about circling flight, a long-span glider flying in
a moderately-tight circle, a fuselage-mounted AOA or one on the inboard
wing would be somewhat useless, since the inboard wing would stall well
before reaching the critical AOA at the fuselage. So now we need
multiple sensors, one at each wing tip and possibly one or two at the
fuselage with a complex set of electronics and software to sort all the
data out and decide the proper answer to give the pilot.

Then there are the atmospheric effects. Say you're flying along on
final into a strong headwind (common here in Kansas) and you encounter a
significant wind shear. This could be caused by a frontal passage or
gust from a nearby storm that you are trying to avoid, but more likely a
simple wind shadow from a hill, a row of tall trees, a hangar, ... You
go from 15 or 20 knots above stall speed to 5 knots below in a matter of
a couple of seconds. What sensor would alert you quickly, reliably, and
give you extra time to react and avoid the stall?

Most of the fatal and serious injury accidents occur while setting up
the landing pattern when the glider is allowed to slow too much and go
to too large an AOA. If I were want to equip my glider with a warning
system, and a purely uncertified one at that since I do know first hand
about certification in my day job, I would use a simple differential
pressure sensor to measure the airspeed from the delta between total and
static pressure and use electronics to trigger an audable warning
whenever the airspeed was less than say 12 knots over 1-g stall (not too
loud though, maybe my wife's voice saying 'Speed Up'). I would only
turn this system on when I enter downwind and am preparing to land.
Extra info when most needed.

Just my 2 cents worth,

...... Neal

Bill Daniels wrote:
>
> Tufts are good and yes, students should see them.
>
> However, tufts show boundary layer behavior not angle of attack and
> streamlines. Start with the little smoke tunnel in the classroom and then
> show them the tufts in flight.
>
> Bill Daniels
>
>

[Bill Daniels]

This discussion needs to be divided into two subjects, stall warners and AOA
indicators. They are really two very different devices.

A stall warning device tells you that you've made a mistake. An AOA
indicator can tell you that you are about to make a mistake. A stall warner
is just a on-off binary device. An AOA indicator provides a continuum of
information across the whole speed range.

AOA tells you about safety margins and the rate of change of that margin. A
stall warning device doesn't - unless it's set at a large margin over stall
in which case it will be constantly triggered by turbulence and pilots will
turn it off. A Cessna-style stall warning would drive a pilot nuts if
installed in a glider.

The point that AOA varies across the span when thermalling is a good one.
Any device mounted on the fuselage won't provide data on the flow at the
wing tips. But, modern gliders have wings designed to prevent tip stall so
fuselage mounted AOA sensors are still useful. Damning AOA indicators
because they aren't perfect is a straw man argument. We have no perfect
instruments but they are still useful.

AOA indicators are better than ASI's at low speed where there are large
errors in airspeed indications but ASI are better at high speed for things
like Va and Vne. AOA indicators are faster responding and easier to
interpret. i.e. if the needle is in the yellow, push until it isn't. The
airspeed will take care of itself.

Maneuvering for landing in gusty wind shear is exactly where I'd want an
AOA. It will show the maximum gust induced AOA so the airspeed can be
increased just enough that no gust stalls the glider but not so much that
you'll need to dump a lot of energy in ground effect.


Bill Daniels




"Neal Pfeiffer" > wrote in message
et...
> Tufts are probably the best way to visualize the unsteady flow near stall
> (as long as the tufts are not so large that they affect the flow.) The
> tufts show when, where, and how the wing actually stalls. The flight can
> be straight ahead, in a turn, with an accelerated entry, ...
>
> The real question is, when does the wing stall and how can information be
> passed to the pilot to avoid the stall?
>
> Tufts are not a very practical method in normal operation, but they are
> great during the development of a aircraft.
>
> Airspeed has been used widely as the indirect means to avoid stall.
> Airspeed is readily available on any glider and by using a relatively
> simple weight and bank angle correction, one can determine a safe
> airspeed.
>
> AOA vanes on the fuselage are often used on a range of powered aircraft.
> On commercial ones, these are often linked electronically to a stick
> pusher in the cockpit to inhibit stall.
>
> Some small airplanes use leading-edge vanes on the inboard wing and I've
> even seen a small vane on the upper aft portion of the wing on a 1947
> Bonanza.
>
> If you are concerned about circling flight, a long-span glider flying in a
> moderately-tight circle, a fuselage-mounted AOA or one on the inboard wing
> would be somewhat useless, since the inboard wing would stall well before
> reaching the critical AOA at the fuselage. So now we need multiple
> sensors, one at each wing tip and possibly one or two at the fuselage with
> a complex set of electronics and software to sort all the data out and
> decide the proper answer to give the pilot.
>
> Then there are the atmospheric effects. Say you're flying along on final
> into a strong headwind (common here in Kansas) and you encounter a
> significant wind shear. This could be caused by a frontal passage or gust
> from a nearby storm that you are trying to avoid, but more likely a simple
> wind shadow from a hill, a row of tall trees, a hangar, ... You go from
> 15 or 20 knots above stall speed to 5 knots below in a matter of a couple
> of seconds. What sensor would alert you quickly, reliably, and give you
> extra time to react and avoid the stall?
>
> Most of the fatal and serious injury accidents occur while setting up the
> landing pattern when the glider is allowed to slow too much and go to too
> large an AOA. If I were want to equip my glider with a warning system,
> and a purely uncertified one at that since I do know first hand about
> certification in my day job, I would use a simple differential pressure
> sensor to measure the airspeed from the delta between total and static
> pressure and use electronics to trigger an audable warning whenever the
> airspeed was less than say 12 knots over 1-g stall (not too loud though,
> maybe my wife's voice saying 'Speed Up'). I would only turn this system
> on when I enter downwind and am preparing to land. Extra info when most
> needed.
>
> Just my 2 cents worth,
>
> ..... Neal
>
> Bill Daniels wrote:
>>
>> Tufts are good and yes, students should see them.
>>
>> However, tufts show boundary layer behavior not angle of attack and
>> streamlines. Start with the little smoke tunnel in the classroom and
>> then show them the tufts in flight.
>>
>> Bill Daniels

[Eric Greenwell]

Bill Daniels wrote:

> Maneuvering for landing in gusty wind shear is exactly where I'd want an
> AOA. It will show the maximum gust induced AOA so the airspeed can be
> increased just enough that no gust stalls the glider but not so much that
> you'll need to dump a lot of energy in ground effect.

Bill, have you used an AOA indicator in the conditions you describe?
What one was it? And how did you know the "maximum gust induced" AOA it
showed you was the maximum you were going to encounter before landing?

My experience with selecting the proper airspeed in gusty wind shear
conditions is it's better done with a rule of thumb, like "add one-half
the wind speed to the approach speed", or from experience, than a
measurement made (like controllability) when I am high enough not to be
in danger.

My other observation is it's not stalling that's the problem in those
conditions, but controllability: I'm usually well above stalling speed,
but fighting to keep the attitude correct, and especially the altitude
during the flare. I hate it when I'm slammed into the ground, so I
usually touch down well over stall speed.

I suggest 5 to 10 proponents of AOA meters, and other interested pilots,
buy some AOA meters (like from Safeflight, DG , Aircraft Spruce) as a
group. This will reduce the cost for each pilot to try several AOA
meters. Have each member of the group try each of the meter(s) for
while, then report their experiences.

Without experience with meters in cockpits in actual flying conditions,
we're just guessing about how useful they are.

--
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 Daniels]

"Eric Greenwell" > wrote in message
news:UCz9j.4239$Xh1.3090@trndny03...
> Bill Daniels wrote:
>
>> Maneuvering for landing in gusty wind shear is exactly where I'd want an
>> AOA. It will show the maximum gust induced AOA so the airspeed can be
>> increased just enough that no gust stalls the glider but not so much that
>> you'll need to dump a lot of energy in ground effect.
>
> Bill, have you used an AOA indicator in the conditions you describe? What
> one was it? And how did you know the "maximum gust induced" AOA it showed
> you was the maximum you were going to encounter before landing?

Yes, Eric. I've flown with very high quality instruments in airplanes and
jury-rigged "pitch strings" in gliders. The pitch strings don't work as
well as the expensive units but, aside from the hassle, they are nonetheless
very useful.

There's no big mystry about AOA indicators, they go back to the very
beginnings of aviation. They aren't common because of cost and difficulty
implementing them on small airplanes. Until now, nobody gave much thought
to gliders.

Just look at the jitter or swing in the needle/string. The max swing in the
positive direction is the max gust induced AOA. By the time you have flown
the pattern and are on short final, you should have a pretty good idea about
the level of turbulence you are dealing with and have selected a minimum
safe margin for the "over the fence" airspeed.

I've seen pilots who have no real knowledge of just what their gust-stall
margin is so they keep adding airspeed until it's a problem for them on roll
out. It does no good to have a wide margin over stall in the air only to
hit a fence on rollout. Just standing on the ground watching glider
landings shows a wide range of techniques. Some patterns look like a ground
attack fighter rolling in on a target. Others float around the pattern tail
low. I have to believe if they had an AOA indicator, they be more
consistent - or at least, have rational excuses.

In off field landings especially, it's a balance between stall margin in
the air and rollout distance on the ground. I practice a short landing on
every flight - partly to be ready for a possible off field landing and
partly because my trailer is near the approach end and I hate pushing back.
I'd love to have a quality AOA indicator to make those landings easier and
safer.

Bill Daniels

[fred]

On Dec 17, 12:37 pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
> "Eric Greenwell" > wrote in message
>
> news:UCz9j.4239$Xh1.3090@trndny03...
>
> > Bill Daniels wrote:
>
> >> Maneuvering for landing in gusty wind shear is exactly where I'd want an
> >> AOA. It will show the maximum gust induced AOA so the airspeed can be
> >> increased just enough that no gust stalls the glider but not so much that
> >> you'll need to dump a lot of energy in ground effect.
>
> > Bill, have you used an AOA indicator in the conditions you describe? What
> > one was it? And how did you know the "maximum gust induced" AOA it showed
> > you was the maximum you were going to encounter before landing?
>
> Yes, Eric. I've flown with very high quality instruments in airplanes and
> jury-rigged "pitch strings" in gliders. The pitch strings don't work as
> well as the expensive units but, aside from the hassle, they are nonetheless
> very useful.
>
> There's no big mystry about AOA indicators, they go back to the very
> beginnings of aviation. They aren't common because of cost and difficulty
> implementing them on small airplanes. Until now, nobody gave much thought
> to gliders.
>
> Just look at the jitter or swing in the needle/string. The max swing in the
> positive direction is the max gust induced AOA. By the time you have flown
> the pattern and are on short final, you should have a pretty good idea about
> the level of turbulence you are dealing with and have selected a minimum
> safe margin for the "over the fence" airspeed.
>
> I've seen pilots who have no real knowledge of just what their gust-stall
> margin is so they keep adding airspeed until it's a problem for them on roll
> out. It does no good to have a wide margin over stall in the air only to
> hit a fence on rollout. Just standing on the ground watching glider
> landings shows a wide range of techniques. Some patterns look like a ground
> attack fighter rolling in on a target. Others float around the pattern tail
> low. I have to believe if they had an AOA indicator, they be more
> consistent - or at least, have rational excuses.
>
> In off field landings especially, it's a balance between stall margin in
> the air and rollout distance on the ground. I practice a short landing on
> every flight - partly to be ready for a possible off field landing and
> partly because my trailer is near the approach end and I hate pushing back.
> I'd love to have a quality AOA indicator to make those landings easier and
> safer.
>
> Bill Daniels

This is a life saving discussion and the best I've heard or read.
Most, or too many instructors do not know how to teach the subject.
Most cannot tell you why "relative wind" exists,. much less how to
anticipate the maximum aoa. Airfoils are much more forgiving now, but
there is a video of a DG spinning in on final. It's late now and I
don't have the link. The ship that spun in on my field in 68, ended
with bones sticking out and no bleeding. Some of the pieces are still
there to remind skepticks. Bless all of you that care .Fred

[Eric Greenwell]

Bill Daniels wrote:
> I'd love to have a quality AOA indicator to make those landings
> easier and safer.

What did you think of this idea from my post:

> I suggest 5 to 10 proponents of AOA meters, and other interested
> pilots, buy some AOA meters (like from Safeflight, DG , Aircraft
> Spruce) as a group. This will reduce the cost for each pilot to try
> several AOA meters. Have each member of the group try each of the
> meter(s) for while, then report their experiences.

Someone has to try some these devices in gliders, so we have some data
that applies to our sport. As the primary promoter of the value of an
AOA gauge, you seem to be the obvious choice to lead an effort that
proves the value. At that point, a few of the clever people in the sport
will likely develop units more suited to gliders, and maybe bring the
cost down.

There are units available, but I don't see anyone buying and using them.
That suggests to me that, while we all agree it's probably a good idea,
we don't think it's good enough to spend the $500-$2000 to actually buy
and install one. So, someone has to just do it and show the results to us.

--
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

[Ian]

On 17 Dec, 20:37, "Bill Daniels" <bildan@comcast-dot-net> wrote:

> I'd love to have a quality AOA indicator to make those landings easier and
> safer.

I generally find that my attention is fully occupied while landing. If
I had an AoA indicator, I would have to take attention away from
something else to look at it (I always have the audio vario and radio
off for the final approach). Would an AoA also indicator free up some
of my attention, and if so, from what?

Ian

[kirk.stant]

> I generally find that my attention is fully occupied while landing. If
> I had an AoA indicator, I would have to take attention away from
> something else to look at it (I always have the audio vario and radio
> off for the final approach). Would an AoA also indicator free up some
> of my attention, and if so, from what?
>
> Ian

Ian, do you look at your airspeed indicator while landing (well,
during the approach, of course - no one looks at their airspeed while
actually landing, do they?)? If you do, then a properly designed AoA
indicator could make your approaches easier and safer. Remember,
airspeed is just an inaccurate way to show angle of attack - the AoA
gauge shows it directly.

Now, if all gliders had AoA gauges, you could jump from one glider to
another and not worry about what the right approach speed is for the
glider you happen to be in. Ditto min sink, etc. Sure would be nice
with ballasted two-seaters, that can have a significant difference in
approach and thermalling speeds depending on crew and ballast weight.

Right now, the closest we have is the yellow triangle on german
gliders - approach speed at max gross, I think? (please correct me if
I'm wrong on that one).

Still dreaming...

Kirk
66

[Cats]

On Dec 19, 2:38 pm, "kirk.stant" > wrote:
> > I generally find that my attention is fully occupied while landing. If
> > I had an AoA indicator, I would have to take attention away from
> > something else to look at it (I always have the audio vario and radio
> > off for the final approach). Would an AoA also indicator free up some
> > of my attention, and if so, from what?
>
> > Ian
>
> Ian, do you look at your airspeed indicator while landing (well,
> during the approach, of course - no one looks at their airspeed while
> actually landing, do they?)? If you do, then a properly designed AoA
> indicator could make your approaches easier and safer. Remember,
> airspeed is just an inaccurate way to show angle of attack - the AoA
> gauge shows it directly.

Why might an AoA guage be any more accurate than an ASI?



> Now, if all gliders had AoA gauges, you could jump from one glider to
> another and not worry about what the right approach speed is for the
> glider you happen to be in.

But you might be concered about what the correct AoA was for them?



> Right now, the closest we have is the yellow triangle on german
> gliders - approach speed at max gross, I think? (please correct me if
> I'm wrong on that one).

*minimum* suggested approach speed. Assuming the dial is marked
correctly.

[John Smith]

kirk.stant wrote:

> Now, if all gliders had AoA gauges, you could jump from one glider to
> another and not worry about what the right approach speed is for the
> glider you happen to be in.

Whatever happened to the old fashioned custom to familiarize oneself
with the particularities of a glider before flying it?

> Right now, the closest we have is the yellow triangle on german
> gliders - approach speed at max gross, I think? (please correct me if
> I'm wrong on that one).

Nothing to do with German, it's a JAR requirement. Suggested minimal
approach speed at max gross without water ballast. The triangle is
handy, but just reading the POH works, too.

[kirk.stant]

On Dec 19, 12:22 pm, John Smith > wrote:
> kirk.stant wrote:
> > Now, if all gliders had AoA gauges, you could jump from one glider to
> > another and not worry about what the right approach speed is for the
> > glider you happen to be in.
>
> Whatever happened to the old fashioned custom to familiarize oneself
> with the particularities of a glider before flying it?

That's a great custom, which I wholeheartedly endorse. Now, put
yourself in the postion to jump into a variety of gliders in rapid
succession. You are current and qualified in all of them, of course.
But can you instantly recall the exact speeds for all of them, under
pressure, without fail?

My personal experience was in giving commercial rides (sightseeing and
aerobatic) in 2-33s, 2-32s, G-103s, and ASK-21s. With a wide variety
of passenger size, in no particular order, often moving to a different
glider immediately after landing.

Fortunately, one soon learns the individual characteristics of the
gliders one flies frequently, and on a nice big field, a little extra
airspeed doesn't hurt until you slow down in the flare. So TLAR works
surprisingly well.

But it would still be nice to have ACCURATE instrumentation. While
airspeed works, it is by design only an approximation of the correct
speed. We are lucky that most gliders are so forgiving that this is
mainly an academic argument. Now, get slow on your turn to final in a
2-32 and you may wish you had an AoA indicator!
>
> > Right now, the closest we have is the yellow triangle on german
> > gliders - approach speed at max gross, I think? (please correct me if
> > I'm wrong on that one).
>
> Nothing to do with German, it's a JAR requirement. Suggested minimal
> approach speed at max gross without water ballast. The triangle is
> handy, but just reading the POH works, too.

Absolutely correct. I find that I don't use it in my own ship, but
look for it when I get in a club ship that I havn't flown in a while -
as a starting point for pattern speed.

Kirk

[John Smith]

kirk.stant wrote:

> That's a great custom, which I wholeheartedly endorse. Now, put
> yourself in the postion to jump into a variety of gliders in rapid
> succession. You are current and qualified in all of them, of course.
> But can you instantly recall the exact speeds for all of them, under
> pressure, without fail?

Yes. But if I really couldn't and were in the situation you describe, I
just would write them into a little booklet which I could take with me
and consult before getting into the glider. Just as I do with many other
things. (Besides: If you can't remember the exact speeds to fly, why
should you be able to remember the exact AoA to fly?)

> My personal experience was in giving commercial rides (sightseeing and
> aerobatic) in 2-33s, 2-32s, G-103s, and ASK-21s. With a wide variety
> of passenger size, in no particular order, often moving to a different
> glider immediately after landing.

I shudder at the thought that a pilot would give commercial rides to
passengers without being absolutely sure of the exact speeds to fly!

> But it would still be nice to have ACCURATE instrumentation. While
> airspeed works, it is by design only an approximation of the correct
> speed.

It may not be ACCURATE, but it certainly is accurate enough. For me, anyway.

> Now, get slow on your turn to final in a
> 2-32 and you may wish you had an AoA indicator!

The solution is simple: Just don't get slow on your turn to final. This
has been hammered into my head since my very first flight, and it works
for me. I don't see what an AoA instrument could add to this. If you are
distracted enough to get slow with an ASI, then I see no reason why you
wouldn't be distracted enough to get slow with an AoAI.

[toad]

On Dec 19, 3:43 pm, John Smith > wrote:
....snip...
> for me. I don't see what an AoA instrument could add to this. If you are
> distracted enough to get slow with an ASI, then I see no reason why you
> wouldn't be distracted enough to get slow with an AoAI.

This seems to be the real reason people stall. It's not that they
don't know what the speed is, it's that they can't maintain the speed
that they do know !

Todd Smith
3S

[Marc Ramsey]

toad wrote:
> On Dec 19, 3:43 pm, John Smith > wrote:
> ...snip...
>> for me. I don't see what an AoA instrument could add to this. If you are
>> distracted enough to get slow with an ASI, then I see no reason why you
>> wouldn't be distracted enough to get slow with an AoAI.
>
> This seems to be the real reason people stall. It's not that they
> don't know what the speed is, it's that they can't maintain the speed
> that they do know !

An indicator for an AoA meter could consist of something as simple as
three LEDs, say a bright red one for approaching stall, green for
minimum sink, blue for best L/D and above, with the red LED blinking
faster as AoA gets closer to stall. The LEDs could be mounted on a
short stick above the instrument glare shield, or even attached to
sunglasses such that it would always be at the edge of the field of
view. All the interpretation required is that the bright flashing red
light means get the nose down, right now.

No one has said anything about taking away anyones ASI...

Marc

[John Smith]

Marc Ramsey wrote:

> An indicator for an AoA meter could consist of something as simple as
> three LEDs, say a bright red one for approaching stall, green for
> minimum sink, blue for best L/D and above, with the red LED blinking
> faster as AoA gets closer to stall. The LEDs could be mounted on a
> short stick above the instrument glare shield, or even attached to
> sunglasses

Or even better, install a fist which knocks your head every time you get
slow... I still can't see the advantage of three LEDs over one pointer.
Obviously I'm getting old...

[Ian]

On 19 Dec, 14:38, "kirk.stant" > wrote:

> Ian, do you look at your airspeed indicator while landing (well,
> during the approach, of course - no one looks at their airspeed while
> actually landing, do they?)? If you do, then a properly designed AoA
> indicator could make your approaches easier and safer. Remember,
> airspeed is just an inaccurate way to show angle of attack - the AoA
> gauge shows it directly.

This is going to lead on to my second favourite question for
instructors: "We all fly the approach a bit faster if there is likely
to be significant wind shear. As we fly through the wind shear, should
we (a) attempt to keep the higher speed or (b) allow speed to decrease
(which is why we added a bit to start)?

> Now, if all gliders had AoA gauges, you could jump from one glider to
> another and not worry about what the right approach speed is for the
> glider you happen to be in.

Wouldn't I have to worry about what the right approach AoA was
instead?

Ian

[Ian]

On 19 Dec, 20:43, John Smith > wrote:

> I don't see what an AoA instrument could add to this. If you are
> distracted enough to get slow with an ASI, then I see no reason why you
> wouldn't be distracted enough to get slow with an AoAI.

That, I think, is a very, very good point.

Ian

[Marc Ramsey]

John Smith wrote:
> Marc Ramsey wrote:
>
>> An indicator for an AoA meter could consist of something as simple as
>> three LEDs, say a bright red one for approaching stall, green for
>> minimum sink, blue for best L/D and above, with the red LED blinking
>> faster as AoA gets closer to stall. The LEDs could be mounted on a
>> short stick above the instrument glare shield, or even attached to
>> sunglasses
>
> Or even better, install a fist which knocks your head every time you get
> slow... I still can't see the advantage of three LEDs over one pointer.
> Obviously I'm getting old...

Yes, I'm sure someone could provide you with the option of a knock in
the head or even an electric shock (non-lethal, I'd assume), if you
prefer. The problem with pointers is that they don't do much good if
you're currently looking at something else.

Marc

[Ian]

On 19 Dec, 21:26, Marc Ramsey > wrote:

> An indicator for an AoA meter could consist of something as simple as
> three LEDs, say a bright red one for approaching stall, green for
> minimum sink, blue for best L/D and above, with the red LED blinking
> faster as AoA gets closer to stall.

My glider does all sorts of things as it approaches stall. It gets
awful quiet. The stick starts shaking. The vario plummets. If I manage
to miss all these clear signs, why would a small flashing red light
grab my attention?

And can you imagine what would happen with a stall warning sounder?
Pilots used to flying with gear-down warnings would anxiously check he
undercarriage lever ... subconsciously pulling back to give themselves
a bit more time ...

Ian

[kirk.stant]

> > But can you instantly recall the exact speeds for all of them, under
> > pressure, without fail?
>
> Yes. But if I really couldn't and were in the situation you describe, I
> just would write them into a little booklet which I could take with me
> and consult before getting into the glider. Just as I do with many other
> things. (Besides: If you can't remember the exact speeds to fly, why
> should you be able to remember the exact AoA to fly?)

Ok, you probably have never flown an aircraft with an actual AOA
system installed. The point is, there is only one AOA you care about,
and that is what a simple AOA gauge shows. Thats it - if you are
below that angle, you are fast. Above that angle, you are slow. No
matter what your gross weight, bank angle, etc.

I've done the booklet route, and it's fine, up to a point.
>
> > My personal experience was in giving commercial rides (sightseeing and
> > aerobatic) in 2-33s, 2-32s, G-103s, and ASK-21s. With a wide variety
> > of passenger size, in no particular order, often moving to a different
> > glider immediately after landing.
>
> I shudder at the thought that a pilot would give commercial rides to
> passengers without being absolutely sure of the exact speeds to fly!

Have you ever been there? When you fly a lot of different gliders,
every one has a different "exact" speed to fly. This is where
experience comes in - you learn real fast the speed ranges for the
gliders involved, and how they feel. And how to carry some extra
airspeed in the pattern until you can safely get rid of it.

> > But it would still be nice to have ACCURATE instrumentation. While
> > airspeed works, it is by design only an approximation of the correct
> > speed.
>
> It may not be ACCURATE, but it certainly is accurate enough. For me, anyway.

Yes, and for me too. But that doesn't mean we can't have something
better. Otherwise, with that logic, we would be all still flying with
uncompensated pellet varios. Sure they work, but we can do better!
>
> > Now, get slow on your turn to final in a
> > 2-32 and you may wish you had an AoA indicator!
>
> The solution is simple: Just don't get slow on your turn to final. This
> has been hammered into my head since my very first flight, and it works
> for me. I don't see what an AoA instrument could add to this. If you are
> distracted enough to get slow with an ASI, then I see no reason why you
> wouldn't be distracted enough to get slow with an AoAI.

ARGGG you just do not understand the concept. Oh well, fun discussion
anyway.

Cheers, and Merry Chrismas!

Kirk

[Marc Ramsey]

Ian wrote:
> On 19 Dec, 21:26, Marc Ramsey > wrote:
>
>> An indicator for an AoA meter could consist of something as simple as
>> three LEDs, say a bright red one for approaching stall, green for
>> minimum sink, blue for best L/D and above, with the red LED blinking
>> faster as AoA gets closer to stall.
>
> My glider does all sorts of things as it approaches stall. It gets
> awful quiet. The stick starts shaking. The vario plummets. If I manage
> to miss all these clear signs, why would a small flashing red light
> grab my attention?

Because, unless you're offering an open invitation for me to fly your
glider, I've flown a number that don't give such clear signs,
particularly in landing flap.

> And can you imagine what would happen with a stall warning sounder?
> Pilots used to flying with gear-down warnings would anxiously check he
> undercarriage lever ... subconsciously pulling back to give themselves
> a bit more time ...

Did I say anything about a sounder?

Marc

[toad]

On Dec 19, 4:26 pm, Marc Ramsey > wrote:
> toad wrote:
> > On Dec 19, 3:43 pm, John Smith > wrote:
> > ...snip...
> >> for me. I don't see what an AoA instrument could add to this. If you are
> >> distracted enough to get slow with an ASI, then I see no reason why you
> >> wouldn't be distracted enough to get slow with an AoAI.
>
> > This seems to be the real reason people stall. It's not that they
> > don't know what the speed is, it's that they can't maintain the speed
> > that they do know !
>
> An indicator for an AoA meter could consist of something as simple as
> three LEDs, say a bright red one for approaching stall, green for
> minimum sink, blue for best L/D and above, with the red LED blinking
> faster as AoA gets closer to stall. The LEDs could be mounted on a
> short stick above the instrument glare shield, or even attached to
> sunglasses such that it would always be at the edge of the field of
> view. All the interpretation required is that the bright flashing red
> light means get the nose down, right now.
>
> No one has said anything about taking away anyones ASI...
>
> Marc

I didn't think that were advocating taking away the ASI.

Let me re-phrase my point, since everybody has a different take.

Glider pilots stall because 1) they are distracted from the airspeed
or 2) they attempt to fly too slow to "maximize" performance.
Changing the reference from ASI to AOA doesn't seem to address either
of these issues. Maybe it's because I fly a glider than warns me
about impending stall in the traditional ways. (stick back, low
noise, mushy controls, etc ...).

I agree that holding a max performance target might be improved by an
AOA indicator, but don't see it worth that much money.

Todd Smith
3S

[Scott[_1_]]

Cats wrote:

>
>
> Why might an AoA guage be any more accurate than an ASI?
>
>
>
>

Because an AoA gauge responds directly with "relative wind"
Airspeed indicators respond to ram air pressure measured against static
pressure. Have you ever noticed that your airspeed indicator seems to
read higher in the winter due to denser air (assuming you live in a
climate with vastly different temps between summer and winter). Also,
have you ever noticed your airspeed indicator reads lower at higher
altitudes (due to less dense air)? AoA is accurate regardless of the
above mentioned differences.

--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)

[John Smith]

Scott wrote:

> Have you ever noticed that your airspeed indicator seems to
> read higher in the winter due to denser air
....

Which is a very good thing, considering that the aerodynamic behaviour
of an airfoil changes with the air density. Back to field 1.

[Scott[_1_]]

If you are too busy on landing to watch an AoA indicator you must
therefore be too busy to watch an airspeed indicator. I don't have much
time in gliders but in my powered plane, I usually glance at the ASI as
I level the wings on final, then I just use visual (and wind noise)
references to make the landing with an occasional glance at ASI as I
start the roundout and flare. I think the AoA would be most useful at
altitude when flying a tight spiral in a column of lift...

Scott


Ian wrote:

> On 17 Dec, 20:37, "Bill Daniels" <bildan@comcast-dot-net> wrote:
>
>
>>I'd love to have a quality AOA indicator to make those landings easier and
>>safer.
>
>
> I generally find that my attention is fully occupied while landing. If
> I had an AoA indicator, I would have to take attention away from
> something else to look at it (I always have the audio vario and radio
> off for the final approach). Would an AoA also indicator free up some
> of my attention, and if so, from what?
>
> Ian

--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)

[Andreas Maurer[_1_]]

On Wed, 19 Dec 2007 13:53:20 -0800 (PST), Ian
> wrote:


>And can you imagine what would happen with a stall warning sounder?
>Pilots used to flying with gear-down warnings would anxiously check he
>undercarriage lever ... subconsciously pulling back to give themselves
>a bit more time ...

Correct.

I once had the pleasure to see a live performance of one of the oldest
aircraft-related jokes:
Belly landing of our ASW-24. One could hear the gear warning all over
the airfield. Pilot got out and commented that he was wondering where
all that noise was suddenly coming from during his final approach.


Bye
Andreas

[Eric Greenwell]

Scott wrote:

> Because an AoA gauge responds directly with "relative wind"
> Airspeed indicators respond to ram air pressure measured against static
> pressure. Have you ever noticed that your airspeed indicator seems to
> read higher in the winter due to denser air (assuming you live in a
> climate with vastly different temps between summer and winter). Also,
> have you ever noticed your airspeed indicator reads lower at higher
> altitudes (due to less dense air)? AoA is accurate regardless of the
> above mentioned differences.

Do you mean "for the same power setting"? Engines tend to produce more
power in cold temperatures than hot, so perhaps that would explain it.
In glider, what you might notice is your ground speed is lower (e.g.,
when landing) in the winter than summer, even though you have the same
airspeed indication.

It's not a problem - it's a benefit!

--
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

[Chuck Griswold]

WOW, What a thread!
The only AoA's that I'm familiar with are huge wedge
shaped things that
stick out on the side of the fuselage. I wouldn't want
one of those on my
glider.
I'm sure you guys are talking about a much simpler
arrangement. I'm
also sure that they are much more accurate than the
ones I'm familiar
with. That being said, this is where I stick my foot
in my mouth, IAS and
AoA probably would be much more help in a thermal than
landing. I think
Jim Pane once taped a piece of yarn to the side of
his canopy for
thermaling. You might check with him. If you are doing
spot landings the
IAS is not accurate enough. (I used to actually stall
on downwind, just to
check out where the needle pointed. gives you a very
accurate reference
point. And if just shooting a landing a 1.3 VS would
give you plenty of
margin. How much are we going to spend for this AoA?
And why is
everyone so worried about stalling on final. If you
are low and slow think
about putting it down long before you get to final.
I can almost guarantee
that in that situation you will be glued to the airspeed.

Two cents worth
Chuck

[Martin Gregorie[_1_]]

Marc Ramsey wrote:
> toad wrote:
>> On Dec 19, 3:43 pm, John Smith > wrote:
>> ...snip...
>>> for me. I don't see what an AoA instrument could add to this. If you are
>>> distracted enough to get slow with an ASI, then I see no reason why you
>>> wouldn't be distracted enough to get slow with an AoAI.
>>
>> This seems to be the real reason people stall. It's not that they
>> don't know what the speed is, it's that they can't maintain the speed
>> that they do know !
>
> An indicator for an AoA meter could consist of something as simple as
> three LEDs, say a bright red one for approaching stall, green for
> minimum sink, blue for best L/D and above, with the red LED blinking
> faster as AoA gets closer to stall.
>
You could do all that with a single, tri-colour LED, though the colors
would be red/yellow/green. The single LED may well be easier to mount
and I doubt you'd miss any information by having all the colors at the
same point - nobody has (yet) suggested any form of bar-graph display.

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

[J a c k[_2_]]

Ian wrote:


> I generally find that my attention is fully occupied while landing.

When isn't it? I always find myself falling behind somehow whenever I
begin to merely enjoy the scenery.


> If I had an AoA indicator, I would have to take attention away from
> something else to look at it...

There is a thing we in the game call a cross-check: look into it.


> (I always have the audio vario and radio
> off for the final approach).

Now I get it, Ian: you are really a troll/FAA Inspector, here to roil
the waters on r.a.s. We can play that game.

The vario-off mode is OK, if you must reduce the aural clutter, but
please tell us how you believe that turning off a major link (radio) you
have with one of the greatest hazards in flying (other traffic) is going
to improve your longevity: and in the pattern, no less? Horrified minds
want to know.


> Would an AoA...indicator free up some
> of my attention, and if so, from what?

An AoAi would give you a reliable indication of the actual and, in
concert with other instruments (ASi, RoC/Vario) and the seat of your
pants, the potential performance of your wing. There is no single item
that I know of which will virtually fly the aircraft for you: certainly
the AoA will not.

What is it which you would like to be able to do, or to know--and in
what phase of flight?



Jack

[J a c k[_2_]]

John Smith wrote:


> The solution is simple: Just don't get slow on your turn to final.

Thank you, John. Go to the head of the class.

Now, what is "slow"?



Jack

[J a c k[_2_]]

toad wrote:

> On Dec 19, 3:43 pm, John Smith > wrote:

>> I don't see what an AoA instrument could add to this. If you are
>> distracted enough to get slow with an ASI, then I see no reason why you
>> wouldn't be distracted enough to get slow with an AoAI.

> This seems to be the real reason people stall. It's not that they
> don't know what the speed is, it's that they can't maintain the speed
> that they do know !

Again, the nail has been struck directly on its head!

The truth is: they can, but they do not. What prevents them from doing
so? What should they do that they do not do?


Jack

[J a c k[_2_]]

Ian wrote:


>> Now, if all gliders had AoA gauges, you could jump from one glider to
>> another and not worry about what the right approach speed is for the
>> glider you happen to be in.
>
> Wouldn't I have to worry about what the right approach AoA was
> instead?

The stalling angle of attack for a given class of airfoils is very
nearly the same for each. In any case, the indicator could be marked
appropriately, or in some way provide you with that information just as
our present ASi's have green arcs, white arcs, yellow radials, red
radials, and AS bugs, etc. Marc's comment concerning LED's is another
alternative.


Jack

[Bill Daniels]

"Martin Gregorie" > wrote in message
...
> Marc Ramsey wrote:
>> toad wrote:
>>> On Dec 19, 3:43 pm, John Smith > wrote:
>>> ...snip...
>>>> for me. I don't see what an AoA instrument could add to this. If you
>>>> are
>>>> distracted enough to get slow with an ASI, then I see no reason why you
>>>> wouldn't be distracted enough to get slow with an AoAI.
>>>
>>> This seems to be the real reason people stall. It's not that they
>>> don't know what the speed is, it's that they can't maintain the speed
>>> that they do know !
>>
>> An indicator for an AoA meter could consist of something as simple as
>> three LEDs, say a bright red one for approaching stall, green for minimum
>> sink, blue for best L/D and above, with the red LED blinking faster as
>> AoA gets closer to stall.
> >
> You could do all that with a single, tri-colour LED, though the colors
> would be red/yellow/green. The single LED may well be easier to mount and
> I doubt you'd miss any information by having all the colors at the same
> point - nobody has (yet) suggested any form of bar-graph display.
>
> --
> martin@ | Martin Gregorie
> gregorie. | Essex, UK
> org |

20% of males suffer some degree of color blindness. A multi-color LED would
be difficult for them to interpret.

In any event, a 3-color LED is just 3 different LED's in the same case so
stacking 3 LED's in a vertical column is neither more nor less complicated.

[Ian]

On 19 Dec, 21:59, Marc Ramsey > wrote:
> Ian wrote:

> > My glider does all sorts of things as it approaches stall. It gets
> > awful quiet. The stick starts shaking. The vario plummets. If I manage
> > to miss all these clear signs, why would a small flashing red light
> > grab my attention?
>
> Because, unless you're offering an open invitation for me to fly your
> glider, I've flown a number that don't give such clear signs,
> particularly in landing flap.

Fair point. Assuming you are current and can cope with wood, you are
welcome to fly the Pirat!

> > And can you imagine what would happen with a stall warning sounder?
> > Pilots used to flying with gear-down warnings would anxiously check he
> > undercarriage lever ... subconsciously pulling back to give themselves
> > a bit more time ...
>
> Did I say anything about a sounder?

Did I say you did? There has, though, been plenty of discussion of
stall warning devices here in the past.

Ian

[Ian]

On 19 Dec, 21:56, "kirk.stant" > wrote:

> > The solution is simple: Just don't get slow on your turn to final. This
> > has been hammered into my head since my very first flight, and it works
> > for me. I don't see what an AoA instrument could add to this. If you are
> > distracted enough to get slow with an ASI, then I see no reason why you
> > wouldn't be distracted enough to get slow with an AoAI.
>
> ARGGG you just do not understand the concept. Oh well, fun discussion
> anyway.

Could you explain a little more. The situation at the moment seems to
be "every glider (bar a few primaries) has an instrument, which if
given attention, will alert the pilot if s/he is flying too slowly on
approach. Despite this, a few pilots manage to fly too slow and
crash".

If that started off ""every glider (bar a few primaries) has an
instrument, which if given attention, will alert the pilot if s/he is
flying at too high an AoA on approach", can you explain why it would
not end

"Despite this, a few pilots manage to fly at too high an AoA and
crash".

In short, why would pilots who ignore the ASI pay attention for an AoA
meter?

Ian

[Ian]

On 20 Dec, 01:55, J a c k > wrote:
> John Smith wrote:
> > The solution is simple: Just don't get slow on your turn to final.
>
> Thank you, John. Go to the head of the class.
>
> Now, what is "slow"?

That depends on the day. If wind shear is likely it will be
significantly higher than on a calm day. Which means, of course, that
on a windy day the safe AoA for the final turn will be significantly
lower than on a calm day ...

Ian

[Ian]

On 20 Dec, 02:09, J a c k > wrote:
> Ian wrote:
> >> Now, if all gliders had AoA gauges, you could jump from one glider to
> >> another and not worry about what the right approach speed is for the
> >> glider you happen to be in.
>
> > Wouldn't I have to worry about what the right approach AoA was
> > instead?
>
> The stalling angle of attack for a given class of airfoils is very
> nearly the same for each.

So what? The right AoA for approach is determined by more than the
stalling AoA...

Ian

[Ian]

On 19 Dec, 23:33, Scott > wrote:

> > I generally find that my attention is fully occupied while landing. If
> > I had an AoA indicator, I would have to take attention away from
> > something else to look at it (I always have the audio vario and radio
> > off for the final approach). Would an AoA also indicator free up some
> > of my attention, and if so, from what?

> If you are too busy on landing to watch an AoA indicator you must
> therefore be too busy to watch an airspeed indicator.

How on earth do you get that? The ASI is one of the things which
occupies my time on the approach. If I have to watch an AoA indicator
it will have to be instead of something else.

> I don't have much
> time in gliders but in my powered plane, I usually glance at the ASI as
> I level the wings on final, then I just use visual (and wind noise)
> references to make the landing with an occasional glance at ASI as I
> start the roundout and flare.

Yes, that's how I do it. What would you not do in order to watch an
AoA indicator?

Ian

[Ian]

On 20 Dec, 01:51, J a c k > wrote:
> Ian wrote:
> > I generally find that my attention is fully occupied while landing.
>
> When isn't it? I always find myself falling behind somehow whenever I
> begin to merely enjoy the scenery.

Oh, hard luck. Enjoying the scenery is one of the reasons I go flying.

> > If I had an AoA indicator, I would have to take attention away from
> > something else to look at it...
>
> There is a thing we in the game call a cross-check: look into it.

Are you saying that I could look at another indicator without spending
any less time on anything else? What do these things do - relativistic
time distortion?

> > (I always have the audio vario and radio
> > off for the final approach).
>
> Now I get it, Ian: you are really a troll/FAA Inspector, here to roil
> the waters on r.a.s. We can play that game.

FAA? What's that, left-hand-side-of-the-Atlantic boy?

> The vario-off mode is OK, if you must reduce the aural clutter, but
> please tell us how you believe that turning off a major link (radio) you
> have with one of the greatest hazards in flying (other traffic) is going
> to improve your longevity: and in the pattern, no less? Horrified minds
> want to know.

"for the final approach" != "in the pattern"

Any thing which reduces potential distraction during the most
hazardous phase of flying is a Good Thing, in my book. Hearing gliders
isn't nearly as important as seeing them.

Ian

[Andreas Maurer]

On Thu, 20 Dec 2007 01:55:25 GMT, J a c k >
wrote:


>Now, what is "slow"?

The simple fact that you arre still able to write this proves that you
know what "slow" is... ;)


Bye
Andreas

[kirk.stant]

> Could you explain a little more. The situation at the moment seems to
> be "every glider (bar a few primaries) has an instrument, which if
> given attention, will alert the pilot if s/he is flying too slowly on
> approach. Despite this, a few pilots manage to fly too slow and
> crash".
>
> If that started off ""every glider (bar a few primaries) has an
> instrument, which if given attention, will alert the pilot if s/he is
> flying at too high an AoA on approach", can you explain why it would
> not end
>
> "Despite this, a few pilots manage to fly at too high an AoA and
> crash".
>
> In short, why would pilots who ignore the ASI pay attention for an AoA
> meter?
>
> Ian

Ian, we appear to be comparing apples and oranges - you are talking
about not stalling on final, while I am talking about being able to
accurately thermal, and incidentally have a better instrument for
flying accurate approaches. You are absolutely correct that anyone
who ignores all the indications of an approaching stall will likely do
the same when an AOA indicator is installed. That is a different
issue altogether. What we AOA proponents are saying is that the
cherished airspeed indicator is really a poor substitute for an AOA
indicator in certain phases of flight - mainly low speed ones such as
thermalling and approaches - where accurate flying is important. The
fact that we do so well with airspeed just proves that gliders are
really easy to fly, and pilots quickly learn the characteristics of
their glider.

Will an AOA guage make you a safer pilot, in a modern glider? Maybe a
little; its funny how all power planes have to have an AOA (not
airspeed) controlled stall warning device to be certified. In my
experience, light power planes not really more susceptible to approach
stalls than gliders, but there are more distractions - including that
noisy thing in the front just waiting to quit! Yet they mandate stall
warnings.

Again, in my perfect glider, I would have a nice unambiguous AOA
indication of Clmax (for thermalling), Approach Cl (say at 1.3 Vstall)
- maybe change to this when the gear is down; and L/D max (flaps up).
I don't need to know the specific stall AOA - there is no reason to be
slower than Cl max so by definition I need to reduce AOA if I'm above
that. But I do want to be able - regardless of my ballast load and
bank angle - to slow to the most efficient AOA when pulling into a
thermal. When faster than L/D max, I'm probably flying a McCready
speed, which is not affected by AOA, and needs to be set using the
airspeed indicator.

Obviously, my opinion is colored by having actually flown airplanes
with excellent AOA systems, and by my wish to optimise my soaring for
XC and racing. I really think that within a few years someone will
come up with a simple, low drag, accurate AOA system that will be
adopted by the same group of pilots who eagerly adopted radios, TE,
audio varios, glide computers, GPS, PDA moving maps, transponders,
ELTs, traffic detection devices - all those "unecessary" gadgets that
clutter up our cockpits but, in my opinion, make soaring safer, more
efficient, and more fun.

Cheers,

Kirk

[toad]

On Dec 20, 9:42 am, "kirk.stant" > wrote:
....snip...
> Obviously, my opinion is colored by having actually flown airplanes
> with excellent AOA systems, and by my wish to optimise my soaring for
> XC and racing.
....snip...
>
> Cheers,
>
> Kirk

Kirk,

Could you summarize for me _how_ you used the AOA indicator in those
aircraft, which aircraft and under what conditions ?

I am curious to the actual use(s).

Thanks
Todd Smith
3S

[Ian]

On 20 Dec, 14:42, "kirk.stant" > wrote:

> Ian, we appear to be comparing apples and oranges - you are talking
> about not stalling on final, while I am talking about being able to
> accurately thermal, and incidentally have a better instrument for
> flying accurate approaches.

I wonder how much "flying at Clmax" matters in good thermalling
compared with "being in the right bit of the thermal"?

> Obviously, my opinion is colored by having actually flown airplanes
> with excellent AOA systems, and by my wish to optimise my soaring for
> XC and racing. I really think that within a few years someone will
> come up with a simple, low drag, accurate AOA system that will be
> adopted by the same group of pilots who eagerly adopted radios, TE,
> audio varios, glide computers, GPS, PDA moving maps, transponders,
> ELTs, traffic detection devices - all those "unecessary" gadgets that
> clutter up our cockpits but, in my opinion, make soaring safer, more
> efficient, and more fun.

If it does these things I'll be all for it. If it costs less than
twenty quid I may even buy one. As a matter of interest, how do you
define "efficient" here?

Ian

[Martin Gregorie[_1_]]

Bill Daniels wrote:
>
> 20% of males suffer some degree of color blindness. A multi-color LED would
> be difficult for them to interpret.
>
> In any event, a 3-color LED is just 3 different LED's in the same case so
> stacking 3 LED's in a vertical column is neither more nor less complicated.
>
That doesn't apply to them all.

There is a three lead version which is just a red and a green LED in one
package but there's also a two lead type where the applied voltage
controls the colour.

I remember experimenting with one of these as the output of an LM 358
op-amp and was able to get any colour across the range red to green from
it by adjusting the input voltage. I was thinking of the latter type and
that it would be easier to mount on the glare shield because it only
needs a 3mm hole or a very small enclosure.

I take you point about colour blindness though, but that would apply to
any tri-LED arrangement unless it was big enough for it to be obvious
just which LED was on.

I'd suggest that there are better displays to use: a 10 segment bar
graph type indicator should be best, arranged so that the segments
turned on from the bottom. The more segments that are on, the higher the
AOA. The option of making it flash as the AOA gets close to the stall
would be a nice feature. It could use LED or LCD technology. Best of
all, this type of display is small, so in many cases it could be placed
alongside the ASI without causing a panel rebuild. If the vertical
display was less than 6mm wide I could even get it into my Libelle's
panel between the T&B and the ASI, which is top center, just where I
like it.


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

[Eric Greenwell]

kirk.stant wrote:
> In my
> experience, light power planes not really more susceptible to approach
> stalls than gliders,

By approach stalls, so you mean stall on final approach? I thought that
was a rare accident gliders, and that most stalls during landing
occurred in the turns.

> but there are more distractions - including that
> noisy thing in the front just waiting to quit! Yet they mandate stall
> warnings.

I don't know the reason that it's mandated, but that noisy thing up
front does change things significantly. For example, under power in my
motorglider, the nose attitude at 50 knots can vary from below the
horizon to above the horizon; the attitude while gliding at 50 knots is
constant and consistent. So, I suggest determining a safe AOA is harder
in powered aircraft, and this makes a stall warning more valuable.

--
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

[kirk.stant]

> Kirk,
>
> Could you summarize for me _how_ you used the AOA indicator in those
> aircraft, which aircraft and under what conditions ?
>
> I am curious to the actual use(s).
>
> Thanks
> Todd Smith
> 3S

Sure. I used AOA in T-38s (a little - not much flight time in those)
and in F-4s (about 2000 hours in those). In my current job, I fly a
variety of F-15 simulators (the real thing, not PC games) and use AOA
all the time. Have also a few flight in F-16s and a lot of time in
F-16 simulators, which use AOA in the approach and landing
configuration.

In a nutshell, AOA is used anytime optimum performance is required
from the wing - be it turning, flying an approach, flying for max
range, recovering from a dive, etc. Since fighters can vary weight a
lot due to fuel burn and store (weapons) configuration, it's
impractical to try to use airspeed other than as a general guide to
your energy state - your airspeed tells you how much instantaneous
energy you have to maneuver, then you fly at the AOA that matches the
type of turn you want - less AOA is conserves energy, more AOA turns
faster, etc. If you are flying for max range or max endurance, again
there is a recommended AOA to fly at - it will stay the same while
the actual airspeed changes based on gross weight, configuration, and
altitude. Finally, in the pattern, you figure out the approximate
airspeed and AOA based on fuel and stores remaining, then crosscheck
the two - if they agree, it's easier to fly AOA on most jets (F-4
especially, F-15 less so).

Now, compared to gliders, these are all extremely low aspect ratio,
and that will exaggerate AOA effects. But the aerodynamic priciples
are the same.

Finally, someone questioned about whether it's better to thermal
efficiently or in the best part of the themal. The answer, IMHO, is
that you should strive to do both. Right now we have wonderful
instruments to help us find the best lift. But we still use a crude
instrument to fly efficiently. Well, actually, most people probably
thermal more by feel and attitude than by staring at the airspeed
indicator.

End of war story.

Cheers,

Kirk

[Dan G]

On Dec 20, 5:17 pm, "kirk.stant" > wrote:
> Sure. I used AOA in T-38s (a little - not much flight time in those)
> and in F-4s (about 2000 hours in those). In my current job, I fly a
> variety of F-15 simulators (the real thing, not PC games) and use AOA
> all the time. Have also a few flight in F-16s and a lot of time in
> F-16 simulators, which use AOA in the approach and landing
> configuration.

Excellent post Kirk. I was about to ask if anyone had fighter-jet
experience and you do! I was going to ask as I recall that in an
accident report on a fatal stall/spin after a missed approach to a
carrier by a F-14 one of the key aspects had been the crew's
monitoring of the AoA. IIRC - though I'm not sure I do - the rear-seat
crew member actually calls out the AoA to the front-seat pilot, who
has too many tasks to do to also include checking the AoA in their
scan.

> Finally, someone questioned about whether it's better to thermal
> efficiently or in the best part of the themal. The answer, IMHO, is
> that you should strive to do both. Right now we have wonderful
> instruments to help us find the best lift. But we still use a crude
> instrument to fly efficiently. Well, actually, most people probably
> thermal more by feel and attitude than by staring at the airspeed
> indicator.

I was thinking the same thing. I have often wondered about the best
speed to fly at any given moment when thermalling, including using
that online calculator thing to get some guidelines which were a fair
bit faster than I thought they would be. As you say, it's odd that we
have great varios, but nothing very good to get the most from our
wings.

I'd be interested in an AoA indicator for performance reasons, but not
so much for safety, where I personally think a good safety margin on
the ASI does the job (plus not leaving it too late to have to pick a
small field to land in, so ground-roll distance is such a factor).


Dan

[toad]

On Dec 20, 12:17 pm, "kirk.stant" > wrote:
> > Kirk,
>
> > Could you summarize for me _how_ you used the AOA indicator in those
> > aircraft, which aircraft and under what conditions ?
>
> > I am curious to the actual use(s).
>
> > Thanks
> > Todd Smith
> > 3S
>
> Sure. I used AOA in T-38s (a little - not much flight time in those)
> and in F-4s (about 2000 hours in those). In my current job, I fly a
> variety of F-15 simulators (the real thing, not PC games) and use AOA
> all the time. Have also a few flight in F-16s and a lot of time in
> F-16 simulators, which use AOA in the approach and landing
> configuration.
>
> In a nutshell, AOA is used anytime optimum performance is required
> from the wing - be it turning, flying an approach, flying for max
> range, recovering from a dive, etc. Since fighters can vary weight a
> lot due to fuel burn and store (weapons) configuration, it's
> impractical to try to use airspeed other than as a general guide to
> your energy state - your airspeed tells you how much instantaneous
> energy you have to maneuver, then you fly at the AOA that matches the
> type of turn you want - less AOA is conserves energy, more AOA turns
> faster, etc. If you are flying for max range or max endurance, again
> there is a recommended AOA to fly at - it will stay the same while
> the actual airspeed changes based on gross weight, configuration, and
> altitude. Finally, in the pattern, you figure out the approximate
> airspeed and AOA based on fuel and stores remaining, then crosscheck
> the two - if they agree, it's easier to fly AOA on most jets (F-4
> especially, F-15 less so).
>
> Now, compared to gliders, these are all extremely low aspect ratio,
> and that will exaggerate AOA effects. But the aerodynamic priciples
> are the same.
>
> Finally, someone questioned about whether it's better to thermal
> efficiently or in the best part of the themal. The answer, IMHO, is
> that you should strive to do both. Right now we have wonderful
> instruments to help us find the best lift. But we still use a crude
> instrument to fly efficiently. Well, actually, most people probably
> thermal more by feel and attitude than by staring at the airspeed
> indicator.
>
> End of war story.
>
> Cheers,
>
> Kirk

Kirk,

I understand (in theory) how you would fly at an optimal AOA, but I
was hoping for a more procedural idea on how to use an AOA indicator.
Do you use it like a "control instrument", like an attitude indicator,
or a "perfomance instrument", like the airspeed ?

Todd
3S

PS. It sounds like you work at some training or simulation
development group for Boeing, St Louis ?

[Dan G]

On Dec 19, 9:48 pm, Ian > wrote:
> This is going to lead on to my second favourite question for
> instructors: "We all fly the approach a bit faster if there is likely
> to be significant wind shear. As we fly through the wind shear, should
> we (a) attempt to keep the higher speed or (b) allow speed to decrease
> (which is why we added a bit to start)?

What's the answer? I've thought about this myself. I tend to try to
maintain the higher speed until round-out, when I stop periodically
checking the ASI and concentrate fully on the view out.


Dan

[Wayne Paul]

I think this entire thread can be summed up as follows:

If you have had the opportunity to fly with an AOA for an extended period of
time ... you would like to have one in your sailplane.

If you haven't had the opportunity to fly with an AOA ... you don't seen the
need or value.

Beyond that, all this discussion is academic and I am getting tired of the
thread.

Respectfully,

Wayne
HP-14 "6F"
A-3B SkyWarrior / A-6A Intruder Bombardier who has observed 1000+ carrier
landing from the cockpit.

P.S. I would like to have an AOA in my old HP-14.
http://www.soaridaho.com/Schreder


"kirk.stant" > wrote in message
...
>> Kirk,
>>
>> Could you summarize for me _how_ you used the AOA indicator in those
>> aircraft, which aircraft and under what conditions ?
>>
>> I am curious to the actual use(s).
>>
>> Thanks
>> Todd Smith
>> 3S
>
> Sure. I used AOA in T-38s (a little - not much flight time in those)
> and in F-4s (about 2000 hours in those). In my current job, I fly a
> variety of F-15 simulators (the real thing, not PC games) and use AOA
> all the time. Have also a few flight in F-16s and a lot of time in
> F-16 simulators, which use AOA in the approach and landing
> configuration.
>
> In a nutshell, AOA is used anytime optimum performance is required
> from the wing - be it turning, flying an approach, flying for max
> range, recovering from a dive, etc. Since fighters can vary weight a
> lot due to fuel burn and store (weapons) configuration, it's
> impractical to try to use airspeed other than as a general guide to
> your energy state - your airspeed tells you how much instantaneous
> energy you have to maneuver, then you fly at the AOA that matches the
> type of turn you want - less AOA is conserves energy, more AOA turns
> faster, etc. If you are flying for max range or max endurance, again
> there is a recommended AOA to fly at - it will stay the same while
> the actual airspeed changes based on gross weight, configuration, and
> altitude. Finally, in the pattern, you figure out the approximate
> airspeed and AOA based on fuel and stores remaining, then crosscheck
> the two - if they agree, it's easier to fly AOA on most jets (F-4
> especially, F-15 less so).
>
> Now, compared to gliders, these are all extremely low aspect ratio,
> and that will exaggerate AOA effects. But the aerodynamic priciples
> are the same.
>
> Finally, someone questioned about whether it's better to thermal
> efficiently or in the best part of the themal. The answer, IMHO, is
> that you should strive to do both. Right now we have wonderful
> instruments to help us find the best lift. But we still use a crude
> instrument to fly efficiently. Well, actually, most people probably
> thermal more by feel and attitude than by staring at the airspeed
> indicator.
>
> End of war story.
>
> Cheers,
>
> Kirk

[Ian]

On 20 Dec, 18:18, "Wayne Paul" > wrote:
> I think this entire thread can be summed up as follows:
>
> If you have had the opportunity to fly with an AOA for an extended period of
> time ... you would like to have one in your sailplane.

Doesn't follow. Just because one person who has flown with an AoA
indicator would like one in his glider does not mean that every who
has would.

Ian

[Ian]

On 20 Dec, 17:46, Dan G > wrote:
> On Dec 19, 9:48 pm, Ian > wrote:
>
> > This is going to lead on to my second favourite question for
> > instructors: "We all fly the approach a bit faster if there is likely
> > to be significant wind shear. As we fly through the wind shear, should
> > we (a) attempt to keep the higher speed or (b) allow speed to decrease
> > (which is why we added a bit to start)?
>
> What's the answer?

Both, depending on who you ask. I'm in favour of not fannying about
with aircraft attitude near the ground and letting the airspeed fall
if that's what the wind shear wants it to do.

Ian

[Bob Whelan[_2_]]

Ian wrote:
> On 20 Dec, 18:18, "Wayne Paul" > wrote:
>> I think this entire thread can be summed up as follows:
>>
>> If you have had the opportunity to fly with an AOA for an extended period of
>> time ... you would like to have one in your sailplane.
>
> Doesn't follow. Just because one person who has flown with an AoA
> indicator would like one in his glider does not mean that every who
> has would.
>
> Ian
I haven't (had the opportunity to fly w. an AoA indicator)...but I would
(like one in my [flapped] sailplane).

That noted, I do tend to agree w. Wayne there's an awful lot of
'religious belief' (subliminal ax-grinding, etc.) being repeated in this
thread that 'en-murkens' its intrinsic value.

Regards,
Bob - instrumentational minimalist - W.


P.S. With a bow to Thread Creep (and Winter, dry laugh)...as
fascinating a topic as AoA is, and as much as it affects the aerodynamic
behavior of wings, equally fascinating (to me, anyway) is the gamut of
human responses the topic has so-far illuminated. It ranges from
well-intentioned 'educators,' to inexperienced 'strong holders of
opinion skeptically resistant to change from instrumentational
status-quo.' We all know who we are!

What's fascinating to me is: What is it about 'topics' that leads to
stark opinional divergences as: a) this 'AoA discussion' vs. b) the
almost manic avidity underlying GPS overwhelm-ment of the (previously
widely held, and,) rule-forbidden resistance to navigation aids in both
badge and contest venues? I mean, w. the PW5 and silicone-in-wax
topics, we can at least sense the underlying reasons for rabidity, but
I'm struggling in this case!

There. My one attempted contribution to Northern Hemisphere Winter ROTS
(Rabidity of Topics Syndrome).

[Bob Whelan[_3_]]

Ian wrote:
> On 20 Dec, 18:18, "Wayne Paul" > wrote:
>> I think this entire thread can be summed up as follows:
>>
>> If you have had the opportunity to fly with an AOA for an extended period of
>> time ... you would like to have one in your sailplane.
>
> Doesn't follow. Just because one person who has flown with an AoA
> indicator would like one in his glider does not mean that every who
> has would.
>
> Ian
I haven't (had the opportunity to fly w. an AoA indicator)...but I would
(like one in my [flapped] sailplane).

That noted, I do tend to agree w. Wayne there's an awful lot of
'religious belief' (subliminal ax-grinding, etc.) being repeated in this
thread that 'en-murkens' its intrinsic value.

Regards,
Bob - instrumentational minimalist - W.


P.S. With a bow to Thread Creep (and Winter, dry laugh)...as
fascinating a topic as AoA is, and as much as it affects the aerodynamic
behavior of wings, equally fascinating (to me, anyway) is the gamut of
human responses the topic has so-far illuminated. It ranges from
well-intentioned 'educators,' to inexperienced 'strong holders of
opinion skeptically resistant to change from instrumentational
status-quo.' We all know who we are!

What's fascinating to me is: What is it about 'topics' that leads to
stark opinional divergences as: a) this 'AoA discussion' vs. b) the
almost manic avidity underlying GPS overwhelm-ment of the (previously
widely held, and,) rule-forbidden resistance to navigation aids in both
badge and contest venues? I mean, w. the PW5 and silicone-in-wax
topics, we can at least sense the underlying reasons for rabidity, but
I'm struggling in this case!

There. My one attempted contribution to Northern Hemisphere Winter ROTS
(Rabidity of Topics Syndrome).

[J a c k[_2_]]

Ian wrote:


> How on earth do you get that? The ASI is one of the things which
> occupies my time on the approach. If I have to watch an AoA indicator
> it will have to be instead of something else.
>
>> I don't have much
>> time in gliders but in my powered plane, I usually glance at the ASI as
>> I level the wings on final, then I just use visual (and wind noise)
>> references to make the landing with an occasional glance at ASI as I
>> start the roundout and flare.
>
> Yes, that's how I do it. What would you not do in order to watch an
> AoA indicator?


Speed up your scan, Ian.


Jack

[J a c k[_2_]]

Ian wrote:


> Are you saying that I could look at another indicator without spending
> any less time on anything else?

One can give adequate attention to every instrument which can fit on a
glider panel, and many more.


[....]


>> The vario-off mode is OK, if you must reduce the aural clutter, but
>> please tell us how you believe that turning off a major link (radio) you
>> have with one of the greatest hazards in flying (other traffic) is going
>> to improve your longevity....

> Any thing which reduces potential distraction during the most
> hazardous phase of flying is a Good Thing, in my book.

I find the radio useful for expanding awareness of those things which
are not readily visible. Continuous three-hundred-sixty degree
all-aspect awareness may be impossible for humans, but expanding what we
do have is always good. Having too much information is far more rare
than is sub-standard processing.


> Hearing gliders isn't nearly as important as seeing them.

Seeing other aircraft is often aided by hearing radio transmissions.
Have you literally heard an aircraft you didn't first see? When you do,
you may wish you had had some indication of its location prior to your
close encounter. The radio is one way of improving your chances. I would
not want to restrict my ability to receive pertinent information from
air or ground sources.



Jack

[Cats]

On Dec 21, 9:58*am, J a c k > wrote:
> Ian wrote:
> > Are you saying that I could look at another indicator without spending
> > any less time on anything else?
>
> One can give adequate attention to every instrument which can fit on a
> glider panel, and many more.
>
> [....]
>
> >> The vario-off mode is OK, if you must reduce the aural clutter, but
> >> please tell us how you believe that turning off a major link (radio) you
> >> have with one of the greatest hazards in flying (other traffic) is going
> >> to improve your longevity....
> > Any thing which reduces potential distraction during the most
> > hazardous phase of flying is a Good Thing, in my book.
>
> I find the radio useful for expanding awareness of those things which
> are not readily visible. Continuous three-hundred-sixty degree
> all-aspect awareness may be impossible for humans, but expanding what we
> do have is always good. Having too much information is far more rare
> than is sub-standard processing.
>
> > Hearing gliders isn't nearly as important as seeing them.
>
> Seeing other aircraft is often aided by hearing radio transmissions.
> Have you literally heard an aircraft you didn't first see? When you do,
> you may wish you had had some indication of its location prior to your
> close encounter. The radio is one way of improving your chances. I would
> not want to restrict my ability to receive pertinent information from
> air or ground sources.

I also find the radio useful to listen for downwind calls, along with
the communication from launchpoint to winch. That's all we hear on
our ground frequency so it's not a lot and it's useful (to me). I
also like to have the vario on as whilst sink & lift can be obvious
(10 down certainly is!), it points it out very clearly and helps me
adjust the circuit to suit. A lot of my worst circuits have been
flown without the audio vario.

[Ian]

On 21 Dec, 10:35, Cats > wrote:

> I also find the radio useful to listen for downwind calls, along with
> the communication from launchpoint to winch. That's all we hear on
> our ground frequency so it's not a lot and it's useful (to me). I
> also like to have the vario on as whilst sink & lift can be obvious
> (10 down certainly is!), it points it out very clearly and helps me
> adjust the circuit to suit. A lot of my worst circuits have been
> flown without the audio vario.

As I wrote, " ... final approach ..."

Ian

[Ian]

On 21 Dec, 09:58, J a c k > wrote:
> Ian wrote:
> > Are you saying that I could look at another indicator without spending
> > any less time on anything else?
>
> One can give adequate attention to every instrument which can fit on a
> glider panel, and many more.

For a suitable definition of "adequate", of course you can. I prefer
to be looking for other gliders, myself.

> I find the radio useful for expanding awareness of those things which
> are not readily visible.

It also has a tendancy to concentrate attention on the gliders you can
here. Accidents have happened - to powered aircraft as well - when
pilots assumed that what they could hear was what they could see,

Ian

[Ian]

On 21 Dec, 08:57, J a c k > wrote:
> Ian wrote:

> > Yes, that's how I do it. What would you not do in order to watch an
> > AoA indicator?
>
> Speed up your scan, Ian.

OK, so your answer is "look at everything else a bit less"?

Thanks,

Ian

[Ian]

On 20 Dec, 02:09, J a c k > wrote:

> The stalling angle of attack for a given class of airfoils is very
> nearly the same for each. In any case, the indicator could be marked
> appropriately, or in some way provide you with that information just as
> our present ASi's have green arcs, white arcs, yellow radials, red
> radials, and AS bugs, etc. Marc's comment concerning LED's is another
> alternative.

Would you prefer to know about the free stream AoA or the local one -
which you will recall is generally significantly different at low
speeds. And how would you deal with washout? Or turns? None of these,
I imagine, would be a concern for fast moving aircraft with relatively
low aspect ratio wings.

Ian

[Ralph Jones[_2_]]

On Fri, 21 Dec 2007 03:58:11 -0600, J a c k >
wrote:
[snip]
>Have you literally heard an aircraft you didn't first see?

I certainly have, and it was another glider. I don't recommend it.

>When you do,
>you may wish you had had some indication of its location prior to your
>close encounter.

Bloody well right I did...

rj

[Bert Willing[_2_]]

I had a buddy who was killed in his sailplane when he was hit by a powered
plane while on final (the 3 people in the plane died even faster).

Bert

"Ian" > wrote in message
...
> On 21 Dec, 10:35, Cats > wrote:
>
>> I also find the radio useful to listen for downwind calls, along with
>> the communication from launchpoint to winch. That's all we hear on
>> our ground frequency so it's not a lot and it's useful (to me). I
>> also like to have the vario on as whilst sink & lift can be obvious
>> (10 down certainly is!), it points it out very clearly and helps me
>> adjust the circuit to suit. A lot of my worst circuits have been
>> flown without the audio vario.
>
> As I wrote, " ... final approach ..."
>
> Ian

[Martin Gregorie[_1_]]

Ian wrote:
> On 20 Dec, 14:42, "kirk.stant" > wrote:
>
>> Ian, we appear to be comparing apples and oranges - you are talking
>> about not stalling on final, while I am talking about being able to
>> accurately thermal, and incidentally have a better instrument for
>> flying accurate approaches.
>
> I wonder how much "flying at Clmax" matters in good thermalling
> compared with "being in the right bit of the thermal"?
>
Minor correction: you should be thermaling at min.sink, which is the
point at which Cl^3/Cd^2 is maximized.

This is not in general the same as Cl max. Min.sink is usually at a
slightly lower AOA than CL max because Cd is rising steeply with
increasing AOA in the Cl max region. As a result, by the time you've
slowed to Cl max you've passed min.sink and your sinking speed has
started to increase.

Since the polar is usually flatter on the faster side of min.sink I
think you're better off thermaling somewhere between the min.sink and
best glide speeds, preferably nearer the former. Best glide is the speed
where Cl/Cd is a maximum.


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

[Ian]

On 21 Dec, 16:11, "Bert Willing" >
wrote:

> "Ian" > wrote in message
>
> ...
>
> > On 21 Dec, 10:35, Cats > wrote:
>
> >> I also find the radio useful to listen for downwind calls, along with
> >> the communication from launchpoint to winch. That's all we hear on
> >> our ground frequency so it's not a lot and it's useful (to me). I
> >> also like to have the vario on as whilst sink & lift can be obvious
> >> (10 down certainly is!), it points it out very clearly and helps me
> >> adjust the circuit to suit. A lot of my worst circuits have been
> >> flown without the audio vario.
>
> > As I wrote, " ... final approach ..."

> I had a buddy who was killed in his sailplane when he was hit by a powered
> plane while on final (the 3 people in the plane died even faster).

That's very sad.

However, like all individual cases, it doesn't really add much
evidence. Some might say that it shows how important it is to have a
radio on. Some might say it shows how important it is not to be
distracted by a vario ... or radio.

Ian

[J a c k[_2_]]

Ian wrote:


> Would you prefer to know about the free stream AoA or the local one...?


I have never received a bit of help from the free-stream. Like anything
free, it has little value. I prefer ground speed.

As to local AoA--how local is your airfoil? You needn't ask which
airfoil. I leave the aerodynamics questions to S-H, DG, et al. If they
insist on building wings using multiple airfoil sections, then it is up
to them to determine whether, and where, to place AoA sensors.


Jack

[J a c k[_2_]]

Ian wrote:
> On 21 Dec, 10:35, Cats > wrote:
>
>> I also find the radio useful to listen for downwind calls, along with
>> the communication from launchpoint to winch. That's all we hear on
>> our ground frequency so it's not a lot and it's useful (to me). I
>> also like to have the vario on as whilst sink & lift can be obvious
>> (10 down certainly is!), it points it out very clearly and helps me
>> adjust the circuit to suit. A lot of my worst circuits have been
>> flown without the audio vario.
>
> As I wrote, " ... final approach ..."

But final approach is the easy part, Ian. You have so few alternatives
left, after all.

Don't most die in the final turn?



Jack

[J a c k[_2_]]

Ian wrote:


>> I find the radio useful for expanding awareness of those things which
>> are not readily visible.
>
> It also has a tendancy to concentrate attention on the gliders you can
> here. Accidents have happened - to powered aircraft as well - when
> pilots assumed that what they could hear was what they could see,


I very nearly included a reference to that in a recent response to you.
I'm glad you mentioned the fallacy of believing that those you hear are
those you see, or that there is no one whom you do not hear. Yours is
not an argument for discontinuing radio monitoring, however.

Your position seems to be that removing as many inputs as possible will
insure a focus on flying the final approach safely. Again, I believe
that expanding your awareness and prioritizing your responses in real
time is far safer than pre-determining what you wish to know and what
you can afford at any cost to ignore.

Admittedly, as I get older I also wish to reduce the cacophony of
stimuli, but I also believe there is a limit beyond which we must not
cocoon ourselves. Better to keep pushing our limits outward, even as we
might wish to do otherwise.

Fortunately, or otherwise, I have some small experience in very complex
piloting situations, including urgent life-or-death dialogs on three
different radios--each on a different frequency band--in a rather
challenging combat environment. I don't expect others to have a similar
need ever to operate near their true limits. But it does color my views
of the topic of awareness, processing, and prioritizing cockpit information.

Enjoy the new season, and always be safe.



Jack

[J a c k[_2_]]

Ian wrote:


> ...like all individual cases, it doesn't really add much
> evidence. Some might say that it shows how important it is to have a
> radio on. Some might say it shows how important it is not to be
> distracted by a vario ... or radio.


Is that an argument for ignoring statistical aggregations of individual
events, or the experience of generations of pilots distilled into
training manuals and, hopefully, regulations?


Jack

[Ian]

On 21 Dec, 21:21, J a c k > wrote:
> Ian wrote:
>
> > ...like all individual cases, it doesn't really add much
>
> > evidence. Some might say that it shows how important it is to have a
> > radio on. Some might say it shows how important it is not to be
> > distracted by a vario ... or radio.
>
> Is that an argument for ignoring statistical aggregations of individual
> events, or the experience of generations of pilots distilled into
> training manuals and, hopefully, regulations?

It's an argument for not reading too much into an individual case,
that's all.

Incidentally, it's worth remembering that every significant change to
a training manual or regulation indicates a willingness to admit that
the distilled experience of generations of pilots has, in some
respect, been wrong.

Or would you care for me to make an argument that since generations of
glider pilots have seen no need for AoA indicators, they must be
useless ... ?

Ian

[Ian]

On 21 Dec, 20:52, J a c k > wrote:
> Ian wrote:
> > On 21 Dec, 10:35, Cats > wrote:
>
> >> I also find the radio useful to listen for downwind calls, along with
> >> the communication from launchpoint to winch. That's all we hear on
> >> our ground frequency so it's not a lot and it's useful (to me). I
> >> also like to have the vario on as whilst sink & lift can be obvious
> >> (10 down certainly is!), it points it out very clearly and helps me
> >> adjust the circuit to suit. A lot of my worst circuits have been
> >> flown without the audio vario.
>
> > As I wrote, " ... final approach ..."
>
> But final approach is the easy part, Ian. You have so few alternatives
> left, after all.

Yes. That's why I don't see any great problem in having audio
distractions off and concentrating on landing.

Normally I soar with the radio off, turn it on when I decide to
return, use it as appropriate in the circuit and kill it when it's not
going to be of any more use.

> Don't most die in the final turn?

The overwhelming majority survive the final turn!

Ian

[Ian]

On 21 Dec, 21:17, J a c k > wrote:

> Your position seems to be that removing as many inputs as possible will
> insure a focus on flying the final approach safely.

Extraneous inputs.

Ian

[Ian]

On 21 Dec, 09:58, J a c k > wrote:
> Ian wrote:

> Seeing other aircraft is often aided by hearing radio transmissions.
> Have you literally heard an aircraft you didn't first see?

Are you remembering that in the UK we have a very limited range of
frequencies, and that it is quite possible to be able to hear calls
from gliders at several different airfields at once? I have on
occasion wasted time trying to see the glider which has just called
downwind at an airfield ten miles from the one I am about to land at.

Ian

[J a c k[_2_]]

Ian wrote:

> Or would you care for me to make an argument that since generations of
> glider pilots have seen no need for AoA indicators, they must be
> useless?


Go ahead--make your day.


Jack

[J a c k[_2_]]

Ian wrote:


>> Don't most die in the final turn?
>
> The overwhelming majority survive the final turn!


Don't most who die in the pattern, die in attempting the final turn?


Jack

[J a c k[_2_]]

Ian wrote:

> Are you remembering that in the UK we have a very limited range of
> frequencies, and that it is quite possible to be able to hear calls
> from gliders at several different airfields at once?

As we do here in the USA. When airborne, we hear calls from multiple
glider organizations, other skydiving activities in addition to the one
based at our field, as well as the other calls associated with each of
the respective airport's operations. The FAA has determined that we will
use a particular frequency from a very limited range of available
frequencies, when operating to or from the airport.


> I have on occasion wasted time trying to see the glider which has just called
> downwind at an airfield ten miles from the one I am about to land at.

You're a poster-child for proper radio procedure, if not for turning off
the radio. Why not set a better example for them?


Jack

[Ian]

On 21 Dec, 22:58, J a c k > wrote:
> Ian wrote:
> >> Don't most die in the final turn?
>
> > The overwhelming majority survive the final turn!
>
> Don't most who die in the pattern, die in attempting the final turn?


.... or shortly afterwards.

Ian

[Denis]

fred a écrit :

> A favorite question I use for instruction... Which wing in a turn has
> the greatest angle of attack?

Would you be so kind to give us the answer please ?

[Nyal Williams]

The inside wing; it travels a lesser distance while
sinking the same amount as the outside wing.

No one seems to have observed that the AoA is instantaneous
whereas the ASI indicates what the aircraft was doing
moments ago. The AoA is especially useful for helping
students understand relative wind and its consequences;
this cannot be done with the ASI.

At 02:18 22 December 2007, Denis wrote:
>fred a écrit :
>
>> A favorite question I use for instruction... Which
>>wing in a turn has
>> the greatest angle of attack?
>
>Would you be so kind to give us the answer please ?
>

[Eric Greenwell]

Nyal Williams wrote:
> The inside wing; it travels a lesser distance while
> sinking the same amount as the outside wing.
>
> No one seems to have observed that the AoA is instantaneous
> whereas the ASI indicates what the aircraft was doing
> moments ago.

I don't think this is true: all the ASI I've had or checked seemed to
respond in less than a second. Surely that's fast enough to keep up with
the glider? Just try blowing gently into a pitot and see how quick the
needle is. If takes "moments" to respond, you should check the indicator
and the pitot line.

The reason we are told to "fly attitude and don't chase the airspeed" is
it takes the glider a while settle down to a steady speed, not because
the ASI is slow.


--
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

[Wayne Paul]

"Eric Greenwell" > wrote in message
news:gi2bj.303$pi7.43@trndny02...
> Nyal Williams wrote:
>> The inside wing; it travels a lesser distance while
>> sinking the same amount as the outside wing.
>>
>> No one seems to have observed that the AoA is instantaneous
>> whereas the ASI indicates what the aircraft was doing
>> moments ago.
>
> I don't think this is true: all the ASI I've had or checked seemed to
> respond in less than a second. Surely that's fast enough to keep up with
> the glider? Just try blowing gently into a pitot and see how quick the
> needle is. If takes "moments" to respond, you should check the indicator
> and the pitot line.
>
> The reason we are told to "fly attitude and don't chase the airspeed" is
> it takes the glider a while settle down to a steady speed, not because the
> ASI is slow.
>
Eric,

Just a short observation. If you had an AOA you would notice an AOA
increase as you open your spoilers while maintaining a constant speed and a
decrease as you closed them.

Wayne

[Cats]

On Dec 21, 10:42*pm, Ian > wrote:
> On 21 Dec, 09:58, J a c k > wrote:
>
> > Ian wrote:
> > Seeing other aircraft is often aided by hearing radio transmissions.
> > Have you literally heard an aircraft you didn't first see?
>
> Are you remembering that in the UK we have a very limited range of
> frequencies, and that it is quite possible to be able to hear calls
> from gliders at several different airfields at once? I have on
> occasion wasted time trying to see the glider which has just called
> downwind at an airfield ten miles from the one I am about to land at.
>
> Ian

Gliders at our airfield prefix their downwind call with 'XXX Traffic'
so there is no doubt who they are addressing. OK. sometimes we get
'XXX Base' but it's still unambiguous.

[Mike Lindsay]

>>
>Eric,
>
>Just a short observation. If you had an AOA you would notice an AOA
>increase as you open your spoilers while maintaining a constant speed and a
>decrease as you closed them.
>
>Wayne
>
>
Why not? Surely the glider would be sinking quicker so the AoA would
increase when you open your spoilers?
--
Mike Lindsay

[Martin Gregorie[_1_]]

Cats wrote:
> On Dec 21, 10:42 pm, Ian > wrote:
>> On 21 Dec, 09:58, J a c k > wrote:
>>
>>> Ian wrote:
>>> Seeing other aircraft is often aided by hearing radio transmissions.
>>> Have you literally heard an aircraft you didn't first see?
>> Are you remembering that in the UK we have a very limited range of
>> frequencies, and that it is quite possible to be able to hear calls
>> from gliders at several different airfields at once? I have on
>> occasion wasted time trying to see the glider which has just called
>> downwind at an airfield ten miles from the one I am about to land at.
>>
>> Ian
>
> Gliders at our airfield prefix their downwind call with 'XXX Traffic'
> so there is no doubt who they are addressing. OK. sometimes we get
> 'XXX Base' but it's still unambiguous.
>
Snap. We make blind calls to "xxx radio" giving approach direction
before joining the circuit and on downwind to give circuit direction and
intended runway. This is in accordance with CAP 413, as all glider
pilots using a radio should know.

Anybody not prefixing the call to a typical glider field with "xxx
radio" is in violation, so a light bollocking would be entirely in order.


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

[Martin Gregorie[_1_]]

Mike Lindsay wrote:
>> Eric,
>>
>> Just a short observation. If you had an AOA you would notice an AOA
>> increase as you open your spoilers while maintaining a constant speed and a
>> decrease as you closed them.
>>
>> Wayne
>>
>>
> Why not? Surely the glider would be sinking quicker so the AoA would
> increase when you open your spoilers?
>
I agree that, once stabilized at the original airspeed with brakes open
the AOA will be a bit higher to compensate for loss of lift, but the AOA
variation during the transition may depend on the glider type.

Some gliders pitch down automatically and accelerate when the brakes are
opened (G103). Others raise the nose slightly and decelerate as the
brakes are opened, so require a good shove on the stick to hold the
airspeed constant (Puchacz). Ditto an ASW-20 as you select landing flap.
The waggling of the AOA needle may be quite different in these cases.


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

[Eric Greenwell]

Wayne Paul wrote:
> "Eric Greenwell" > wrote in message
> news:gi2bj.303$pi7.43@trndny02...
>> Nyal Williams wrote:
>>> No one seems to have observed that the AoA is instantaneous
>>> whereas the ASI indicates what the aircraft was doing
>>> moments ago.
>> I don't think this is true: all the ASI I've had or checked seemed to
>> respond in less than a second. Surely that's fast enough to keep up with
>> the glider? Just try blowing gently into a pitot and see how quick the
>> needle is. If takes "moments" to respond, you should check the indicator
>> and the pitot line.
>>
>> The reason we are told to "fly attitude and don't chase the airspeed" is
>> it takes the glider a while settle down to a steady speed, not because the
>> ASI is slow.
>>
> Eric,
>
> Just a short observation. If you had an AOA you would notice an AOA
> increase as you open your spoilers while maintaining a constant speed and a
> decrease as you closed them.

True, but the ASI is still indicating correctly, not lagging as Nyal
seemed to suggest.

So, do we fly the same AOA with the spoilers open as when they are
closed? Supposed they are just "cracked" open, half open, fully open -
do I need to know a different AOA for each spoiler position?

And if I use landing flaps for the landing instead of the thermal flap
setting, do I need to yet another list of AOA for different spoiler
settings?

--
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

[Ralph Jones[_2_]]

On Sat, 22 Dec 2007 06:39:08 GMT, Eric Greenwell
> wrote:

>Nyal Williams wrote:
>> The inside wing; it travels a lesser distance while
>> sinking the same amount as the outside wing.
>>
>> No one seems to have observed that the AoA is instantaneous
>> whereas the ASI indicates what the aircraft was doing
>> moments ago.
>
>I don't think this is true: all the ASI I've had or checked seemed to
>respond in less than a second. Surely that's fast enough to keep up with
>the glider? Just try blowing gently into a pitot and see how quick the
>needle is. If takes "moments" to respond, you should check the indicator
>and the pitot line.
>
>The reason we are told to "fly attitude and don't chase the airspeed" is
>it takes the glider a while settle down to a steady speed, not because
>the ASI is slow.

That's precisely his point. Change the AoA, and the drag changes.
Change the drag, and the glider accelerates (positively or
negatively). Then the airspeed changes, and only then does the ASI get
a chance to tell you about it.

"Fly attitude and don't chase the airspeed" really means "fly AoA and
don't chase the airspeed", but if you don't have an AoA indicator, you
have to use the attitude as a substitute for AoA. And it's a
second-rate substitute.

rj

[Eric Greenwell]

Ralph Jones wrote:
> "Fly attitude and don't chase the airspeed" really means "fly AoA and
> don't chase the airspeed", but if you don't have an AoA indicator, you
> have to use the attitude as a substitute for AoA. And it's a
> second-rate substitute.

Please pardon me if I sound a bit cranky, but how can attitude be a
"second-rate substitute" for something that we don't even have?

And what would a "first-rate substitute" be?

Not a single poster here has flown with an AOA meter in their glider,
except a few using yarn taped to the side of their canopy. Is that what
we should be using instead of attitude and airspeed?

"Show me the money".

--
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

[Marc Ramsey[_2_]]

Eric Greenwell wrote:
> Not a single poster here has flown with an AOA meter in their glider,
> except a few using yarn taped to the side of their canopy. Is that what
> we should be using instead of attitude and airspeed?

Actually, I have flown with the factory supplied AoA meter (differential
pressure) in my DG-600, but I could never get the darn thing calibrated
properly...

Marc

[Eric Greenwell]

Marc Ramsey wrote:
> Eric Greenwell wrote:
>> Not a single poster here has flown with an AOA meter in their glider,
>> except a few using yarn taped to the side of their canopy. Is that
>> what we should be using instead of attitude and airspeed?
>
> Actually, I have flown with the factory supplied AoA meter (differential
> pressure) in my DG-600, but I could never get the darn thing calibrated
> properly...

Bummer. I'm still hoping we'll hear from some pilots with the newest DG
80x gliders, which has it as standard equipment (I think that's right...).

--
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

[Greg Arnold]

Marc Ramsey wrote:
> Eric Greenwell wrote:
>> Not a single poster here has flown with an AOA meter in their glider,
>> except a few using yarn taped to the side of their canopy. Is that
>> what we should be using instead of attitude and airspeed?
>
> Actually, I have flown with the factory supplied AoA meter (differential
> pressure) in my DG-600, but I could never get the darn thing calibrated
> properly...
>
> Marc

One common problem with many arguments (not just on RAS!) is that people
compare the status quo with an idealized world, and conclude that the
status quo is flawed and must be changed. It seems to me this may be
occurring in the AoA discussion -- many posters have compared a
perfectly functioning AoA indicator with our slow and inaccurate ASIs,
and concluded that AoA indicators are better. But perhaps in the real
world AoA indicators on gliders would be even less accurate than ASIs?

[Marc Ramsey[_2_]]

Greg Arnold wrote:
> Marc Ramsey wrote:
>> Eric Greenwell wrote:
>>> Not a single poster here has flown with an AOA meter in their glider,
>>> except a few using yarn taped to the side of their canopy. Is that
>>> what we should be using instead of attitude and airspeed?
>>
>> Actually, I have flown with the factory supplied AoA meter
>> (differential pressure) in my DG-600, but I could never get the darn
>> thing calibrated properly...
>>
>> Marc
>
> One common problem with many arguments (not just on RAS!) is that people
> compare the status quo with an idealized world, and conclude that the
> status quo is flawed and must be changed. It seems to me this may be
> occurring in the AoA discussion -- many posters have compared a
> perfectly functioning AoA indicator with our slow and inaccurate ASIs,
> and concluded that AoA indicators are better. But perhaps in the real
> world AoA indicators on gliders would be even less accurate than ASIs?

Insufficient evidence. Mine was a 17 year old analog electronic device
hooked up to 17 year old plumbing. It sometimes seemed to work, but not
consistently.

Marc

[Nyal Williams]

Eric,

I should have been more precise in my comment. AoA,
as shown by a piece of yarn will be much quicker than
an ASI. The ASI will respond quickly, as you say,
but it will not arrive at a steady-state indication
for a few moments if the AoA change is considerable
and abrupt. I have no opinion about AoA instruments,
for I have never used one.

In my youth, I saw one used on an inboard strut between
the wings of a bi-plane; it was a blade type that floated
in the air. The pilot swore by it.

At 06:42 22 December 2007, Eric Greenwell wrote:
>Nyal Williams wrote:
>> The inside wing; it travels a lesser distance while
>> sinking the same amount as the outside wing.
>>
>> No one seems to have observed that the AoA is instantaneous
>> whereas the ASI indicates what the aircraft was doing
>> moments ago.
>
>I don't think this is true: all the ASI I've had or
>checked seemed to
>respond in less than a second. Surely that's fast enough
>to keep up with
>the glider? Just try blowing gently into a pitot and
>see how quick the
>needle is. If takes 'moments' to respond, you should
>check the indicator
>and the pitot line.
>
>The reason we are told to 'fly attitude and don't chase
>the airspeed' is
>it takes the glider a while settle down to a steady
>speed, not because
>the ASI is slow.
>
>
>--
>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
>

[01-- Zero One]

"Andreas Maurer" > wrote in message
:



> >Now, what is "slow"?
>
> The simple fact that you arre still able to write this proves that you
> know what "slow" is... ;)
>





Or he is lucky!



Larry

[Scott[_1_]]

One positive advantage to AoA is that it isn't dependent on a static
pressure source. If the static port becomes blocked, ASI readings go
whacko.

AoA appears to be useful for something since I routinely saw them on
military aircraft (which also always had ASI as well).

AoA may not be the definitive answer, but it is another available tool.

Scott


Nyal Williams wrote:

> Eric,
>
> I should have been more precise in my comment. AoA,
> as shown by a piece of yarn will be much quicker than
> an ASI. The ASI will respond quickly, as you say,
> but it will not arrive at a steady-state indication
> for a few moments if the AoA change is considerable
> and abrupt. I have no opinion about AoA instruments,
> for I have never used one.
>
> In my youth, I saw one used on an inboard strut between
> the wings of a bi-plane; it was a blade type that floated
> in the air. The pilot swore by it.
>
> At 06:42 22 December 2007, Eric Greenwell wrote:
>
>>Nyal Williams wrote:
>>
>>>The inside wing; it travels a lesser distance while
>>>sinking the same amount as the outside wing.
>>>
>>>No one seems to have observed that the AoA is instantaneous
>>>whereas the ASI indicates what the aircraft was doing
>>>moments ago.
>>
>>I don't think this is true: all the ASI I've had or
>>checked seemed to
>>respond in less than a second. Surely that's fast enough
>>to keep up with
>>the glider? Just try blowing gently into a pitot and
>>see how quick the
>>needle is. If takes 'moments' to respond, you should
>>check the indicator
>>and the pitot line.
>>
>>The reason we are told to 'fly attitude and don't chase
>>the airspeed' is
>>it takes the glider a while settle down to a steady
>>speed, not because
>>the ASI is slow.
>>
>>
>>--
>>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
>>
>
>
>
>

--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)

[kirk.stant]

On Dec 22, 10:36*pm, Greg Arnold wrote>
> One common problem with many arguments (not just on RAS!) is that people
> compare the status quo with an idealized world, and conclude that the
> status quo is flawed and must be changed. *It seems to me this may be
> occurring in the AoA discussion -- many posters have compared a
> perfectly functioning AoA indicator with our slow and inaccurate ASIs,
> and concluded that AoA indicators are better. *But perhaps in the real
> world AoA indicators on gliders would be even less accurate than ASIs?

Greg, I don't see it that way. I see the basic argument is about AoA
vs airspeed as the more accurate/desirable control instrument for
certain phases of flight (assuming equally good instrumentation for
the AoA and airspeed).

As far as instrument accuracy, AoA and airspeed are fundamentally
different, with different ways to be measured. You define the level
of accuracy you want, and design the sensor and display accordingly.
This is not rocket science - AoA indicators have been around since
before the airspeed indicator, and was probably considered easier to
measure at first!

A side discussion relates to the fact that airspeed indicators are
universal, while AoA sysems are expensive and not common in gliders.
While the appropriate technology is simple and would be easy to
incorporate in a glider while it is being built (a few sets of
pressure ports on each wing, connected to a microprocessor and
display) the current cost is in the $1500 range - plus installation -
so I doubt we'll be seeing a lot of them in cockpits soon. But
picture this: You have the plumbing installed while your new glider
is being built (some tubing - not a lot of cost there, basically it's
another multi-orifice static system in the wings). Then the latest
SN-99 or LX-9999 has the software and connectors builtin (adds $500 to
the box). It might start showing up - first in top of the line
motorgliders, then filtering down.

I fail to understand why looking at ways to make flying more efficient
and safer causes such a defensive response! But then, the same thing
probably happened when the first electric varios came out - "what's
wrong with our PZL? Dont need no stinkin battery, works just fine!
Next you'll want it to make noise!"

Then there was the great GPS debate...or even radios!

Kirk

[Eric Greenwell]

Nyal Williams wrote:
> Eric,
>
> I should have been more precise in my comment. AoA,
> as shown by a piece of yarn will be much quicker than
> an ASI. The ASI will respond quickly, as you say,
> but it will not arrive at a steady-state indication
> for a few moments if the AoA change is considerable
> and abrupt.

Perhaps I misunderstood you. Is the lag you are talking about the time
it takes for the airspeed indication to become steady after you change
the glider's attitude from one steady attitude to another steady
attitude; i.e., from one AOA to another AOA?

If that's what you mean, then I agree: it will take a few moments for
the glider's airspeed to change to the new value.

What I thought you meant was the ASI (airspeed INDICATOR) reacts slowly.

--
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

[J a c k[_2_]]

01-- Zero One wrote:
> "Andreas Maurer" > wrote in message
> :
>
>> >Now, what is "slow"?
>>
>> The simple fact that you arre still able to write this proves that you
>> know what "slow" is... ;)
>>
>
>
>
> Or he is lucky!


Oh, I am--very lucky--and have been for a long time.


Jack

[Ian]

On 24 Dec, 07:26, J a c k > wrote:

> Oh, I am--very lucky--and have been for a long time.

As Arnold Palmer is reported to have said:

"It's a funny thing, but the more I practice, the luckier I get."

Ian

[Ralph Jones[_2_]]

On Sun, 23 Dec 2007 03:23:59 GMT, Eric Greenwell
> wrote:

>Ralph Jones wrote:
>> "Fly attitude and don't chase the airspeed" really means "fly AoA and
>> don't chase the airspeed", but if you don't have an AoA indicator, you
>> have to use the attitude as a substitute for AoA. And it's a
>> second-rate substitute.
>
>Please pardon me if I sound a bit cranky, but how can attitude be a
>"second-rate substitute" for something that we don't even have?
>
>And what would a "first-rate substitute" be?
>

You could probably design one, but okay, I concede the grammatical
point. Let's put it this way: The ASI is to a good AoA meter as Hormel
Potted Meat Food Product is to Underwood Deviled Ham.

rj

[Eric Greenwell]

Ralph Jones wrote:
> On Sun, 23 Dec 2007 03:23:59 GMT, Eric Greenwell
> > wrote:
>
>> Ralph Jones wrote:
>>> "Fly attitude and don't chase the airspeed" really means "fly AoA and
>>> don't chase the airspeed", but if you don't have an AoA indicator, you
>>> have to use the attitude as a substitute for AoA. And it's a
>>> second-rate substitute.
>> Please pardon me if I sound a bit cranky, but how can attitude be a
>> "second-rate substitute" for something that we don't even have?
>>
>> And what would a "first-rate substitute" be?
>>
>
> You could probably design one, but okay, I concede the grammatical
> point. Let's put it this way: The ASI is to a good AoA meter as Hormel
> Potted Meat Food Product is to Underwood Deviled Ham.

You better not be disrespecting Spam! As a 4th generation Hawaiian, I'd
have to hunt you down and hurt you, probably by showing you a video
purchased at the Spam Museum. Of course I've been there! What else can
you do when it rains during a contest at Albert Lea?

Hmmm, am I going to have to explain all this?

--
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

[Pete Brown]

Eric Greenwell and Bill Daniels wrote:

>> I'd love to have a quality AOA indicator to make those landings
>> easier and safer.

It's more than an issue of safety, an AOA indicator will allow you to
optimize flight in all configurations including circling flight at
different wing loadings. The use and construction of such a device, aka
a lift coefficient meter, was discussed in an article by Daniel J.
Altstatt in Soaring Magazine March, 1975, page 22. No doubt a modern
electronic instrument is now feasible.

Pete Brown



>
> What did you think of this idea from my post:
>
>> I suggest 5 to 10 proponents of AOA meters, and other interested
>> pilots, buy some AOA meters (like from Safeflight, DG , Aircraft
>> Spruce) as a group. This will reduce the cost for each pilot to try
>> several AOA meters. Have each member of the group try each of the
>> meter(s) for while, then report their experiences.
>
> Someone has to try some these devices in gliders, so we have some data
> that applies to our sport. As the primary promoter of the value of an
> AOA gauge, you seem to be the obvious choice to lead an effort that
> proves the value. At that point, a few of the clever people in the sport
> will likely develop units more suited to gliders, and maybe bring the
> cost down.
>
> There are units available, but I don't see anyone buying and using them.
> That suggests to me that, while we all agree it's probably a good idea,
> we don't think it's good enough to spend the $500-$2000 to actually buy
> and install one. So, someone has to just do it and show the results to us.
>


--
Peter D. Brown
http://home.gci.net/~pdb/
http://groups.yahoo.com/group/akmtnsoaring/


Going home after a long day
http://farm2.static.flickr.com/1415/1325102827_f322928754_b.jpg

The fleet at Summit. Mt. McKinley is about 45nm away at 20,320 msl.
http://farm1.static.flickr.com/187/437346531_a9cb8d2482_b.jpg

The 170B at Bold near Eklutna Glacier
http://farm1.static.flickr.com/168/437324742_a216d7bb75.jpg

[Sarah Anderson[_2_]]

Here are some links:

http://advanced-flight-systems.com/Products/AOA/aoa.html

As mentioned, aircraft spruce catalogs this and another, vane based one:

http://www.aircraftspruce.com/catalog/inpages/HCIaoa.php
or directly, http://www.hciaviation.com/prod-aoa-a.shtml

And yes, I'd be interested in how well any of these actually work in gliders.
It's not clear the first one has enough resolution for performance info, for example.

--Sarah


Pete Brown wrote:
> Eric Greenwell and Bill Daniels wrote:
>
>>> I'd love to have a quality AOA indicator to make those landings
>>> easier and safer.
>
> It's more than an issue of safety, an AOA indicator will allow you to
> optimize flight in all configurations including circling flight at
> different wing loadings. The use and construction of such a device, aka
> a lift coefficient meter, was discussed in an article by Daniel J.
> Altstatt in Soaring Magazine March, 1975, page 22. No doubt a modern
> electronic instrument is now feasible.
>
> Pete Brown
>
>
>
>>
>> What did you think of this idea from my post:
>>
>>> I suggest 5 to 10 proponents of AOA meters, and other interested
>>> pilots, buy some AOA meters (like from Safeflight, DG , Aircraft
>>> Spruce) as a group. This will reduce the cost for each pilot to try
>>> several AOA meters. Have each member of the group try each of the
>>> meter(s) for while, then report their experiences.
>>
>> Someone has to try some these devices in gliders, so we have some data
>> that applies to our sport. As the primary promoter of the value of an
>> AOA gauge, you seem to be the obvious choice to lead an effort that
>> proves the value. At that point, a few of the clever people in the
>> sport will likely develop units more suited to gliders, and maybe
>> bring the cost down.
>>
>> There are units available, but I don't see anyone buying and using
>> them. That suggests to me that, while we all agree it's probably a
>> good idea, we don't think it's good enough to spend the $500-$2000 to
>> actually buy and install one. So, someone has to just do it and show
>> the results to us.
>>
>
>