AoA keep it going!

"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

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)

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

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

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

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

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

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

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/...22928754_b.jpg

The fleet at Summit. Mt. McKinley is about 45nm away at 20,320 msl.
http://farm1.static.flickr.com/187/4...cb8d2482_b.jpg

The 170B at Bold near Eklutna Glacier
http://farm1.static.flickr.com/168/4...a216d7bb75.jpg

Here are some links:

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

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

http://www.aircraftspruce.com/catalo...ges/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.