AOA indicator poll.

Very awesome! I'd really like one that's displayed like this...
http://www.youtube.com/watch?v=2wlvpJLcf-A

On Sunday, May 24, 2020 at 5:34:54 AM UTC-5, Tim from Pure Glide wrote:
Very awesome! I'd really like one that's displayed like this...
http://www.youtube.com/watch?v=2wlvpJLcf-A

Neat, I'm thinking tweak the S/W for some NeoPixels just under the glareshield.
https://www.adafruit.com/category/168


I wonder what the gadget shows if you are holding constant attitude and fly trough a thermal?

On Sunday, 24 May 2020 14:48:05 UTC+2, wrote:
On Sunday, May 24, 2020 at 5:34:54 AM UTC-5, Tim from Pure Glide wrote:
Very awesome! I'd really like one that's displayed like this...
http://www.youtube.com/watch?v=2wlvpJLcf-A

Neat, I'm thinking tweak the S/W for some NeoPixels just under the glareshield.
https://www.adafruit.com/category/168


I wonder what the gadget shows if you are holding constant attitude and fly trough a thermal?

I have some NeoPixels in the drawer... But for this project it looks not significant to me: I always want the same color at the same position...

The Icon AoA is nice on any airplane with room on the panel. I don't have to say more... This can be displayed on the glass side of our cockpits... It's just a question of software when the serial data stream is available... But the fact is that when the AoA information is the most relevant for safety, I have no time to look for it or find the right page/option of the calculator. The led bar, at a fixed place near the ASI, which is a complementary information and a kind of cross-check indication, is all I need to keep on flying and stay concentrated on the outside.

I choose a 5 leds display AoA with 5 different colors for several reasons:

- Visually, the color gives me an instant indication and doesn't need a lot of training or attention to be interpreted: Green is Ok, Amber means high AoA and high lift, Red = warning, blinking Red = danger. On the other side blue is too low, I should push the flaps forward... white is landing configuration (for a flapped glider) All these color are progressively changing so that the in-between information is there. Ok, it's slightly different for a glider without flaps but it follows the same logic: Green becomes approach AoA and white will be best glide... And this has the same logical aerodynamic meaning in both cases and values are relatively near to each other.

On Tuesday, May 19, 2020 at 1:00:05 PM UTC-7, Luc Job wrote:
Hi!

I have developed last year a solid-state AOA indicator, based on a
differential pressure measurement (total pressure/pressure at angle)

Undoubtedly, this is a primary flight instrument to me:

-It shows where you are aerodynamically speaking, independently of
all the variable parameters: Load, flaps position, airbrakes...etc, and
does not need a calculation or interpretation to check if you are
flying right or not... And if the display is well done you will have a
clear indication of the ongoing tendency towards a safe or dangerous
situation.

-It give me an accurate indication to adapt the flaps position to stay
at the best glide angle through the whole speed range.

-It is a good indication of the optimal attitude during winch launch
and can prevent a high speed stall at high load factor.

Some pictures of my development are available he
https://bit.ly/aoaindicator
On the video the blinking effect is induced by the camera, the leds
simply fade in or out gradually, only the red one blinks at stall angle
or if the AOA rate of increase will induce a stall within 2 seconds...
you can see that the instrument works as good as its free
alternative...

The present system includes:

-A 5 leds indicator, red-amber-green-white-blue. The corresponding
AOA for each led is programmed in flight with a push-button.

-An audio input and output: Instead of adding a warning while flying
at higher AOA than the maximum Cz (minimum sink rate), the
instrument hashes the audio output of the vario gradually, cutting
the sound at stall. This is an excellent indication that something is
wrong without adding noise... You can continue to watch outside
while climbing at the best speed, and avoid to enter a spin in the
middle of others.

-A serial i/o for software upgrade and continuous transmission of the
data to another instrument.

-An optional light sensor to adapt the luminosity to the ambient light
level... But the indirect illumination and a better reflector (in
development) has proved that it is probably unnecessary.

The only hardware modification is the installation of an angled
pressure port at a suitable place: angle is not critical, but flow must
be as undisturbed as possible. On the DG I've put mine under the
nose, about 170 mm from the tip, where I had access to the outer
hull from the inside. I drilled a 2 mm hole and glued a small
pressure chamber inside to plug a 4 mm hose. That's all.

Power drain is lower than 20 mA @ 12V, less on ground as no led is
switched on... So no switch, but an internal polyfuse to avoid any
dangerous current drain... So it is simply added to the (fused)
instruments circuit.

Now as the system proves to be functional and efficient it's time to
do something with it.

Many options are possible:

1) I can order and sell PCB's only, with a BOM and the software...
This is obviously the cheapest way... But components are mostly
SMD... So you need an oven or a lot of patience and skill... Up to
you to make a box adapted to your needs. Price should be about $10
including shipping.

2) I can sell a complete kit with all the components, PCB, software,
connectors and box... Components are not expensive except the 2
pressure sensors ($35 each)... So I should be able to make this for
about $150...

3) If you prefer a complete instrument, ready to plug-in (except the
pressure port installation) the price should be in the 300-400$
range.

All this depends obviously on quantity... So if I have 1'000 orders it
might be significantly cheaper.

At first I need to know how many people might be interested... And
what is the best option for you.

At least we can fly again in Switzerland and France... So it might
take some time for me to build a website for this product...

Luc JOB
DG-800B

I think this is awesome. Gliders have needed this, in fact I think years the SSA even had a contest to develop to an AOA. Once a unit (any style working unit) goes into production, more innovation will follow. Just make sure instead of demands for differing styles, you pony up the $ to purchase when it hits the market.

The 5 led moving + color sounds well thought out. That would certainly be the first thing I'd do with the NeoPixels.

Panel space in my glider is a bit like Survivor. An addition usually means something has to go. The theory on a Neopixel array just under the glareshield is that is will work for this AOA display, but also remain useful if/when it morphs into something else.

Having a functional AOA may change my mind, but I'm hoping it may turn out to be more useful for sensing airmass in addition to impending stall.

On another issue, when you drilled the sensing hole, did you go through a layer of foam? On some gliders, I'm wondering if the hole should be epoxy lined to prevent water intrusion into a inner foam layer.


Looking forward to having one.

On another issue, when you drilled the sensing hole, did you go through a layer of foam? On some gliders, I'm wondering if the hole should be epoxy lined to prevent water intrusion into a inner foam layer.

On most gliders I know, the nose cone isn't made of sandwich... At least on the symmetry plane where you have to drill, as it is the joint of the 2 1/2 parts of the fuselage.

Looking forward to having one.

PCB modified to include an optional 4 wire led control...

Sounds great, thanks

On Tuesday, May 19, 2020 at 3:00:05 PM UTC-5, Luc Job wrote:
Hi!

I have developed last year a solid-state AOA indicator, based on a
differential pressure measurement (total pressure/pressure at angle)

Undoubtedly, this is a primary flight instrument to me:

-It shows where you are aerodynamically speaking, independently of
all the variable parameters: Load, flaps position, airbrakes...etc, and
does not need a calculation or interpretation to check if you are
flying right or not... And if the display is well done you will have a
clear indication of the ongoing tendency towards a safe or dangerous
situation.

-It give me an accurate indication to adapt the flaps position to stay
at the best glide angle through the whole speed range.

-It is a good indication of the optimal attitude during winch launch
and can prevent a high speed stall at high load factor.

Some pictures of my development are available he
https://bit.ly/aoaindicator
On the video the blinking effect is induced by the camera, the leds
simply fade in or out gradually, only the red one blinks at stall angle
or if the AOA rate of increase will induce a stall within 2 seconds...
you can see that the instrument works as good as its free
alternative...

The present system includes:

-A 5 leds indicator, red-amber-green-white-blue. The corresponding
AOA for each led is programmed in flight with a push-button.

-An audio input and output: Instead of adding a warning while flying
at higher AOA than the maximum Cz (minimum sink rate), the
instrument hashes the audio output of the vario gradually, cutting
the sound at stall. This is an excellent indication that something is
wrong without adding noise... You can continue to watch outside
while climbing at the best speed, and avoid to enter a spin in the
middle of others.

-A serial i/o for software upgrade and continuous transmission of the
data to another instrument.

-An optional light sensor to adapt the luminosity to the ambient light
level... But the indirect illumination and a better reflector (in
development) has proved that it is probably unnecessary.

The only hardware modification is the installation of an angled
pressure port at a suitable place: angle is not critical, but flow must
be as undisturbed as possible. On the DG I've put mine under the
nose, about 170 mm from the tip, where I had access to the outer
hull from the inside. I drilled a 2 mm hole and glued a small
pressure chamber inside to plug a 4 mm hose. That's all.

Power drain is lower than 20 mA @ 12V, less on ground as no led is
switched on... So no switch, but an internal polyfuse to avoid any
dangerous current drain... So it is simply added to the (fused)
instruments circuit.

Now as the system proves to be functional and efficient it's time to
do something with it.

Many options are possible:

1) I can order and sell PCB's only, with a BOM and the software...
This is obviously the cheapest way... But components are mostly
SMD... So you need an oven or a lot of patience and skill... Up to
you to make a box adapted to your needs. Price should be about $10
including shipping.

2) I can sell a complete kit with all the components, PCB, software,
connectors and box... Components are not expensive except the 2
pressure sensors ($35 each)... So I should be able to make this for
about $150...

3) If you prefer a complete instrument, ready to plug-in (except the
pressure port installation) the price should be in the 300-400$
range.

All this depends obviously on quantity... So if I have 1'000 orders it
might be significantly cheaper.

At first I need to know how many people might be interested... And
what is the best option for you.

At least we can fly again in Switzerland and France... So it might
take some time for me to build a website for this product...

Luc JOB
DG-800B

Luc I'm confused by some of your statements.

I am a professional, semi-retired, applied aerodynamicist who had done design and performance analysis work for most of the US General Aviation companies.
Aircraft angle of attack (AoA) is defined using a reference line fixed to the fuselage. For a zero-flap configuration, there will be s specific AoA at stall. For a landing-flap deflection, the the maximum lift coefficient will be higher, however, it will occur at an AoA that is several degrees lower. All lift curves for aircraft design at factories worldwide use this convention.

I also have extensive experience with using 5-hole probes in the wind tunnel and in flight (even a rakes of 21 probes behind several locations on the Beech Starship). These are excellent for providing AoA, angle of sideslip (or yaw), and can be calibrated to provide a good measurement of static pressure and total pressure. I have calibrated probes myself in a wind tunnel with calibration curves out well beyond stall angles.

I have seen simple probes systems proposed and developed Garmin and others, however, these do not fully generate a true AoA. I would be interested in seeing how your single probe can generate a true AoA, and particularly for multiple flap angles. I'm skeptical at this point. I look forward to seeing more information.

...... Neal
Wichita, KS
Consulting Engineer

Hi Neal

Your statements are not in contradiciton with mine... And I already mentionned the limits of this sooner in the thread:

The key factors to assume that flaps have little influence on stall AoA of the aircraft a

1)simple airtight whole span flaps, I could add small chord ratio, the kind of flaps we only have on gliders, in summary...

2)low deflection angle, say lower than +-10 degrees to give indicative numbers

3)experimemtal data with a side string: I haven't noticed a significant difference of the side string angle when buffeting and loss of control starts through the whole flaps position range.

There is relatively few publications regarding the above conditions... Please let me know if you find some.

The idea behind the AoA indicator is to help setting the flaps in the right position during normal transition flight, so the first expected pilot's reaction is to adapt the flaps to stay at the right angle whatever could be the wing loading and other factors.

Another useful AoA value corresponds to the lowest sink rate, as you can see on speed polars the lowest sink speed range in relatively narrow and there is about a 10km/h margin between the lowest sink and the complete stall, where the sink rate increase abruptly... If you want to climb, you must avoid this range... And the only instrument that can give you an idea when you are thermalling with a continously changing speed and load factor is the AoA... And this is also in this configuration that safety comes into play.

In the case my sidestring had shown a different critical angle for different flaps position, I would have set the stall point with the maximum positive position before landing postions. So I have a right idea of my margin when thermalling. For any lower flaps position, the stall AoA could only be a few degrees higher... So I'm on the safe side through the whole flight envelope, except maybe with flaps in landing position...

At the recommended approach speed, the AoA with landing flaps is very low, giving a huge margin to reach stall, and in this configuration the goal isn't to be near stall angle, it's to stay at or above approach AoA. And on most if not all gliders the recommended flaps position in gusty contitions is not landing, ist last positive to keep more ailerons control... And this is where the AoA should have been tuned for stall...

And finally, for most of the gliders, you have no flaps to worry about... And the AoA remains a precious helper, specially at low speed when thermalling.

In practice, I think that this simple and cheap AoA indicator is much more than an additional gadget, it gives more significant information than the ASI through the whole flight envelope and an accurate stall warning.

So I don't know if I measure the true AoA... Maybe by chance the instrument gives the same indication as the sidestring only because it sustains the same perturbation and that by chance this perturbation compensate exactely the difference of critical AoA with the flaps for my DG-800B glider only.

But I'm confident that it should work on any glider. I will check this soon on my club's ASK21 and a Ventus 2cxa...

I think I will just keep my side strings. Relatively accurate for my purposes (mainly only thermalling). And I can’t beat the price or simplicity.
Dan