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AOA indicator poll.



 
 
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  #1  
Old May 19th 20, 08:49 PM posted to rec.aviation.soaring
Luc Job
external usenet poster
 
Posts: 2
Default AOA indicator poll.

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

  #2  
Old May 19th 20, 09:30 PM posted to rec.aviation.soaring
Jonathan St. Cloud
external usenet poster
 
Posts: 1,463
Default AOA indicator poll.

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


That is wonderful. An AOA indicator is something that I would purchase for and ASG-29
  #3  
Old May 19th 20, 10:30 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 281
Default AOA indicator poll.

Cool, I did a cal flight in that area this weekend.


Made a new flap setting ring for the ASI. Added an inside piece of tape for the outside pitch string. In flight, added a dot to mark string position for best L/D.

Then checked to see if the center of each flap settings on the ring matched the dot. They did pretty well.

I've been thinking about an electronic AOA for sensing the H&V air direction. I have an Ardinuo and diff transducer rigged to a machined nose piece with a pitot and angled port. It can sense a 1% angle change on the bench with a wind tunnel (some call it a shop vac). But I'm not sure if it would be any better than normal instruments already there.

Your picture shows you also have the pitch string. Have you added the dot and checked to see if the electronics stay's green at different speeds but still on the dot?



  #4  
Old May 20th 20, 09:08 AM posted to rec.aviation.soaring
Luc Job[_2_]
external usenet poster
 
Posts: 22
Default AOA indicator poll.

Hi!

The basic principle comes from this reference:

http://www.nar-associates.com/techni...LowCostAoA.pdf

In order to be accurate for any atmospheric pressure (altitude), you can't make a straight differential measurement of your dynamic pressures. You need a reference pressure.

The thing is relatively tricky as you need to calculate a ratio of pressures to get the AOA... And at low speed the dynamic pressure is low... And the difference between the 2 dynamic pressures is equally low. And you must compute an accurate ratio of these 2 low values...

That's why my system uses 2 $35 pressure gauges: They are internally compensated for temperature and other factors, and outputs a 14 bits signal, with a full range corresponding to a 250 km/h dynamic pressure.

That's the price to pay to be below 1% at 70 km/h... And in practice it works...

The pitch string is corresponding to the instrument... But the string is very sensitive to sideslip... Not the instrument... That makes the side string useful only for calibration, when you can concentrate on keeping the middle string absolutely straight...
  #5  
Old May 20th 20, 09:14 AM posted to rec.aviation.soaring
Luc Job[_2_]
external usenet poster
 
Posts: 22
Default AOA indicator poll.

Hi!

The basic principle comes from this reference:

http://www.nar-associates.com/techni...LowCostAoA.pdf

In order to be accurate for any atmospheric pressure (altitude), you can't make a straight differential measurement of your dynamic pressures. You need a reference pressure.

The thing is relatively tricky as you need to calculate a ratio of pressures to get the AOA... And at low speed the dynamic pressure is low... And the difference between the 2 dynamic pressures is equally low. And you must compute an accurate ratio of these 2 low values...

That's why my system uses 2 $35 pressure gauges: They are internally compensated for temperature and other factors, and outputs a 14 bits signal, with a full range corresponding to a 250 km/h dynamic pressure.

That's the price to pay to be below 1% at 70 km/h... And in practice it works...

The pitch string is corresponding to the instrument... But the string is very sensitive to sideslip... Not the instrument... That makes the side string useful only for calibration, when you can concentrate on keeping the middle string absolutely straight...


  #6  
Old May 20th 20, 01:48 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 281
Default AOA indicator poll.



That's why my system uses 2 $35 pressure gauges: They are internally compensated for temperature and other factors, and outputs a 14 bits signal, with a full range corresponding to a 250 km/h dynamic pressure.

That's the price to pay to be below 1% at 70 km/h... And in practice it works...

The pitch string is corresponding to the instrument... But the string is very sensitive to sideslip...


Excellent, looks like a great plan and paper to read.

Are you going to put the design up on github?

Put me down for #2.


  #7  
Old May 20th 20, 02:46 PM posted to rec.aviation.soaring
Luc Job[_2_]
external usenet poster
 
Posts: 22
Default AOA indicator poll.

Before I publish it, the code needs some cleaning and complements... I need to test the light sensor functions... It was left aside as it proved to be unnecessary until now.

And now I'm working on the PCB design for the 'production' version.

Basically the idea of the 5 leds is to have an indication for the 5 important AOA's to fly a glider:

1)Blinking red is stall.
2)Red (nonblinking) to amber is below Cz max, or below minimum sink rate if you prefer...So on the bad side of the flight envelope, also indicated by the audio perturbation.
3)amber is Cz max or minimum sink rate.
4)green is approach AOA... Logical color for this part of flight.
5)white is best glide angle AOA
6)blue is lower than best glide angle

With an unflapped glider it is in the right order... With a flapped glider, the approach AOA with the flaps in landing position at the recommended approach speed of 1.3 Vs is lower than the best glide angle... So technically the green led should be between the white and the blue... Assuming that you set the blue at the AOA near the Vne...

But on a flapped glider you can also decide that green is best glide angle and white is approach with landing flaps (white arc on ASI)... That's what I have done on my DG... And on some gliders you have more than 1 landing flaps position... So it's up to you to decide what is the best setting for you and your glider...

On a flapped glider it makes also sense to have the green for the ideal flaps position, increase the flap angle when the color turns towards amber and lower it when it turns white...

  #8  
Old May 20th 20, 04:56 PM posted to rec.aviation.soaring
jfitch
external usenet poster
 
Posts: 1,134
Default AOA indicator poll.

On Wednesday, May 20, 2020 at 6:46:19 AM UTC-7, Luc Job wrote:
Before I publish it, the code needs some cleaning and complements... I need to test the light sensor functions... It was left aside as it proved to be unnecessary until now.

And now I'm working on the PCB design for the 'production' version.

Basically the idea of the 5 leds is to have an indication for the 5 important AOA's to fly a glider:

1)Blinking red is stall.
2)Red (nonblinking) to amber is below Cz max, or below minimum sink rate if you prefer...So on the bad side of the flight envelope, also indicated by the audio perturbation.
3)amber is Cz max or minimum sink rate.
4)green is approach AOA... Logical color for this part of flight.
5)white is best glide angle AOA
6)blue is lower than best glide angle

With an unflapped glider it is in the right order... With a flapped glider, the approach AOA with the flaps in landing position at the recommended approach speed of 1.3 Vs is lower than the best glide angle... So technically the green led should be between the white and the blue... Assuming that you set the blue at the AOA near the Vne...

But on a flapped glider you can also decide that green is best glide angle and white is approach with landing flaps (white arc on ASI)... That's what I have done on my DG... And on some gliders you have more than 1 landing flaps position... So it's up to you to decide what is the best setting for you and your glider...

On a flapped glider it makes also sense to have the green for the ideal flaps position, increase the flap angle when the color turns towards amber and lower it when it turns white...


I am struggling to understand why I would need one, but a couple of technical questions: How well does it work in accelerated flight such as a 50 deg bank? Will you need an adjustment to account for different nose shapes and/or different pressure tube installation locations? What does it indicate in a spin or spin transition to spiral dive?
  #9  
Old May 20th 20, 01:39 AM posted to rec.aviation.soaring
Michael Opitz
external usenet poster
 
Posts: 318
Default AOA indicator poll.


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'd be interested in #3, the complete instrument, ready to plug in.

RO

  #10  
Old May 20th 20, 03:04 AM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 100
Default AOA indicator poll.

Option #3 for me
Will need instruction for installation...
Dan
 




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