AoA keep it going!

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

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

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

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

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.

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.

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

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.

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

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