Glider angle of attack indicator by SafeFlight

It probably works better in rough western conditions. As you said, "pitch
strings" are very sub-optimum AOA indicators. I don't use them because
it's such a hassle closing the canopy without trapping the strings between
the canopy frame and fuselage.

I think it's likely that the SafeFlight vane-type AOA indicator works fine
as long as you are fairly good at keeping the yaw string centered.
SafeFlight has been around selling these things to airplane owners for a
long time. It's nice to see them offering a product for gliders.

Bill Daniels


"jcarlyle" wrote in message
...
I've got pitch strings on both sides of the canopy of my ASW-19, Bill,
but I've not seen this behavior. I'll make an effort to look carefully
the next time thermals appear in Pennsylvania! As was said earlier in
the thread, though, strings on the canopy are greatly affected by yaw.
They might help indicate lift, but they won't really be useful AOA
indicators. And if AOA instruments average out rough air fluctuations,
they won't be too useful as incipient lift indicators. Tough problem!

-John

Bill Daniels wrote:
Many pilots who have tried the "pitch strings" report that they give
advance
warning when entering an area of lift. When you enter the edge of a
thermal, the strings show a sharp increase in AOA several seconds before
the
vario shows lift. This improves the efficiency of "dolphin flying" by
providing an earlier signal of when to start a zoom. One pilot on a
marginal final glide told me, "Without them, I wouldn't have made it
home."
An ASI gives the same signal but it's weaker and harder to interpret.

Most AOA sensors have some damping to smooth the signal in rough air.

I was Googling around, and ran across yet another AOA device. Check
out this site:
http://www.adventureairsports.com/aoa.htm
and pay particular attention to the 3rd photograph. Yaw string and AOA
in one, and not very expensive!

-John

On Dec 9, 6:46 pm, "Bill Daniels" bildan@comcast-dot-net wrote:
I think it's likely that the SafeFlight vane-type AOA indicator works fine
as long as you are fairly good at keeping the yaw string centered.
SafeFlight has been around selling these things to airplane owners for a
long time. It's nice to see them offering a product for gliders.

I think that probably works on an ultralight without an aerodynamic nose
cone. Laminar airflow around a nose cone will be nearly parallel to the
skin at any AOA of interest. That's why the AOA sensor has to be on the
sides of the fuselage.

Bill Daniels

"jcarlyle" wrote in message
...
I was Googling around, and ran across yet another AOA device. Check
out this site:
http://www.adventureairsports.com/aoa.htm
and pay particular attention to the 3rd photograph. Yaw string and AOA
in one, and not very expensive!

-John

On Dec 9, 6:46 pm, "Bill Daniels" bildan@comcast-dot-net wrote:
I think it's likely that the SafeFlight vane-type AOA indicator works
fine
as long as you are fairly good at keeping the yaw string centered.
SafeFlight has been around selling these things to airplane owners for a
long time. It's nice to see them offering a product for gliders.

On Dec 9, 10:09 pm, "Bill Daniels" bildan@comcast-dot-net wrote:
I think that probably works on an ultralight without an aerodynamic nose
cone. Laminar airflow around a nose cone will be nearly parallel to the
skin at any AOA of interest. That's why the AOA sensor has to be on the
sides of the fuselage.

Bill Daniels

Good point. They can also be located on a boom extending away from
the fuselage or wing - as usually seen on prototypes, where accurate,
"true" AOA is needed. Often combined with a yaw sensor (just a fancy
yaw string, really) to measure true sideslip.

I wonder if an AOA vane could be mounted on a modified tail TE/combi
probe? The probe would have to be a lot stiffer to work (at least
that's what she said...).

Kirk

Out of curiosity I made a test. I built a cuff with an 21/2 ft arrow
shaft attached, line up with the wing chord. I had several strings
attached on top of each other about half inch apart and different
length. Very interesting to see how the air responds well ahead of the
leading edge but useless for any useable information. With flaps, the
changes I was interested in were to small in any case.
Udo


On Dec 9, 10:04 pm, jcarlyle wrote:
I was Googling around, and ran across yet another AOA device. Check
out this site:http://www.adventureairsports.com/aoa.htm
and pay particular attention to the 3rd photograph. Yaw string and AOA
in one, and not very expensive!

-John

On Dec 9, 6:46 pm, "Bill Daniels" bildan@comcast-dot-net wrote:



I think it's likely that the SafeFlight vane-type AOA indicator works fine
as long as you are fairly good at keeping the yaw string centered.
SafeFlight has been around selling these things to airplane owners for a
long time. It's nice to see them offering a product for gliders.- Hide quoted text -

- Show quoted text -

Good to hear about an actual experiment, thanks.

Why do you say it was interesting but useless? Did it not give you AoA information?
Interesting you say changes with flaps were too small.. to see?

I wonder if a piano wire probe like

http://www.adventureairsports.com/aoa.htm

but on the nose would work. How far out on the wing was your cuff?

Sarah



Udo wrote:
Out of curiosity I made a test. I built a cuff with an 21/2 ft arrow
shaft attached, line up with the wing chord. I had several strings
attached on top of each other about half inch apart and different
length. Very interesting to see how the air responds well ahead of the
leading edge but useless for any useable information. With flaps, the
changes I was interested in were to small in any case.
Udo


On Dec 9, 10:04 pm, jcarlyle wrote:
I was Googling around, and ran across yet another AOA device. Check
out this site:http://www.adventureairsports.com/aoa.htm
and pay particular attention to the 3rd photograph. Yaw string and AOA
in one, and not very expensive!

-John

On Dec 9, 6:46 pm, "Bill Daniels" bildan@comcast-dot-net wrote:



I think it's likely that the SafeFlight vane-type AOA indicator works fine
as long as you are fairly good at keeping the yaw string centered.
SafeFlight has been around selling these things to airplane owners for a
long time. It's nice to see them offering a product for gliders.- Hide quoted text -
- Show quoted text -

The probe was about 3 ft from the cockpit wall.
You would need something a lot more precise to be of use for flying
efficiently day to day
I could see a resolution of a 1/2 degree or better. with adjustable
dampening. I was trying to see if the theoretical match the real
thing.
To optimize performance you should have something to compare it with
and record it. That is why the annual Idaflieg is such a big deal in
Germany it takes a lot of effort and equipment.
I found that the theoretical for me was close enough and all I needed
was time to fine tune my settings and speed vis a vis other gliders.
When the big day came I gave R.Johnson the speed and flap setting I
thought best and it work out not bad.

Udo



On Dec 10, 10:10 am, Sarah Anderson wrote:
Good to hear about an actual experiment, thanks.

Why do you say it was interesting but useless? Did it not give you AoA information?
Interesting you say changes with flaps were too small.. to see?

I wonder if a piano wire probe like

http://www.adventureairsports.com/aoa.htm

but on the nose would work. How far out on the wing was your cuff?

Sarah



Udo wrote:
Out of curiosity I made a test. I built a cuff with an 21/2 ft arrow
shaft attached, line up with the wing chord. I had several strings
attached on top of each other about half inch apart and different
length. Very interesting to see how the air responds well ahead of the
leading edge but useless for any useable information. With flaps, the
changes I was interested in were to small in any case.
Udo

On Dec 9, 10:04 pm, jcarlyle wrote:
I was Googling around, and ran across yet another AOA device. Check
out this site:http://www.adventureairsports.com/aoa.htm
and pay particular attention to the 3rd photograph. Yaw string and AOA
in one, and not very expensive!

-John

On Dec 9, 6:46 pm, "Bill Daniels" bildan@comcast-dot-net wrote:

I think it's likely that the SafeFlight vane-type AOA indicator works fine
as long as you are fairly good at keeping the yaw string centered.
SafeFlight has been around selling these things to airplane owners for a
long time. It's nice to see them offering a product for gliders.- Hide quoted text -
- Show quoted text -- Hide quoted text -

- Show quoted text -