AoA keep it going!

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

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

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

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

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

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 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