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AOA indicator



 
 
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  #51  
Old April 18th 16, 06:47 AM posted to rec.aviation.soaring
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Default AOA indicator

On Sunday, April 17, 2016 at 9:56:30 PM UTC-7, Jonathan St. Cloud wrote:
Or perhaps you could do it with software as per the original post.


Some flight computers and PDA programs already have "stall warnings" calculated using airspeed and G loading. My sole experience actually using this feature was on a CAI 302, I don't remember it being particularly useful or if it was all that accurate.
  #52  
Old April 18th 16, 10:24 AM posted to rec.aviation.soaring
Dan Daly[_2_]
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On Monday, April 18, 2016 at 1:47:46 AM UTC-4, wrote:
On Sunday, April 17, 2016 at 9:56:30 PM UTC-7, Jonathan St. Cloud wrote:
Or perhaps you could do it with software as per the original post.


Some flight computers and PDA programs already have "stall warnings" calculated using airspeed and G loading. My sole experience actually using this feature was on a CAI 302, I don't remember it being particularly useful or if it was all that accurate.


Why re-invent something currently available? In my SZD-55, it works.
http://www.olk.com.pl/indexen.php?bo...roducts&lpx=26



  #53  
Old April 18th 16, 10:48 AM posted to rec.aviation.soaring
Bruce Hoult
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Default AOA indicator

On Monday, April 18, 2016 at 5:32:22 PM UTC+12, wrote:
On Sunday, April 17, 2016 at 7:09:28 PM UTC-7, Soartech wrote:
A single probe can provide AoA, airspeed, static, and total energy, it just needs more holes and tubing. Better yet, discard the tubing, put all of the electronics and sensors in the probe, send the data to the cockpit via Bluetooth.


While it's true this can be done these days it will require thousands of man-hours of expensive engineering time. You will end up with something like the Garmin AOA system which is like $1400. My idea was to use a very small vane that has negligable drag and low cost electronics with a much lower price to the pilot so that more people will actually own it. This entire discussion has been very helpful to me and am now considering adding the audio tone option for use on landing approach.


Vanes have their own downsides, in particular being rather fragile. If I was working for Garmin, yes, it would take thousands of man-hours of expensive engineering, but I'm not working for Garmin.

For a 2 hole probe with audio output, I'm not seeing where one needs much more than a couple of high resolution absolute or (preferably) differential i2c pressure sensors, a simple audio amplifier, and a cheap microcontroller with DAC. Easy breadboard project, minimal coding, but I can't design a PCB. Only for experimental gliders, of course...


PCBs are easy. I can put you onto a friend who designs PCBs at home in Dunedin, gets them made in China cheap. He even has a small pick-and-place machine at home for production runs up to a few hundred or low thousands of units.

The hard part is the software to filter and calibrate and interpret the signals. It'd take a few hours of flying, recording the signals, and comparing to a known accurate AOA measurement method (e.g. a decent sized vane on a stick out in the freestream)

I did a similar thing with using an Arduino and exposed thermistor to get a precise (0.01 C relative) and stable temperature measurement for my home heating control. On stormy winter nights with a few draughts around it was amazing how noisy the thermistor output was! No, you don't need to control the temperature to 0.01 C ... 0.1 or 0.2 is fine ... but more accurate measurement lets you pick up any trend early. And in fact I found I was able to usually keep the temperature (as measured by the controller anyway) usually within 0.02 just by switching an oil filled electric heater on or off at 30 second intervals. Worst case errors from starting or stopping cooking, boiling the kettle etc were 0.2 to 0.3, corrected in about 20 minutes -- those heaters have a LONG thermal constant.
  #54  
Old April 18th 16, 12:44 PM posted to rec.aviation.soaring
Jonathan St. Cloud
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Or you could use the readily available software already developed as per the information in original post, just like Aspen did.
  #55  
Old April 18th 16, 09:16 PM posted to rec.aviation.soaring
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Default AOA indicator

On Monday, April 18, 2016 at 2:48:16 AM UTC-7, Bruce Hoult wrote:
PCBs are easy. I can put you onto a friend who designs PCBs at home in Dunedin, gets them made in China cheap. He even has a small pick-and-place machine at home for production runs up to a few hundred or low thousands of units.


I do embedded software and know enough about digital logic design to get into trouble, but design of a proper PCB (or analog circuitry) is beyond me. It is getting quite easy to cobble together sophisticated devices on a breadboard.

The hard part is the software to filter and calibrate and interpret the signals. It'd take a few hours of flying, recording the signals, and comparing to a known accurate AOA measurement method (e.g. a decent sized vane on a stick out in the freestream)


I'm not so sure one needs an accurate absolute numeric AoA, so much as a repeatable measure of how close you are to stall AoA. Such a system would need to be calibrated for each glider installation by going up and stalling in various configurations. I have some practical experience on the filtering side, including working with another poster is this group to build a flight computer with digitally differentiated variometer about a decade ago (when there was more of a need for analog circuitry). We did hours of flying (and driving fast up/down steep hills), before we managed to get the filtering right.
  #56  
Old April 18th 16, 09:27 PM posted to rec.aviation.soaring
Craig Funston
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Default AOA indicator

On Monday, April 18, 2016 at 1:16:33 PM UTC-7, wrote:
On Monday, April 18, 2016 at 2:48:16 AM UTC-7, Bruce Hoult wrote:
PCBs are easy. I can put you onto a friend who designs PCBs at home in Dunedin, gets them made in China cheap. He even has a small pick-and-place machine at home for production runs up to a few hundred or low thousands of units.


I do embedded software and know enough about digital logic design to get into trouble, but design of a proper PCB (or analog circuitry) is beyond me.. It is getting quite easy to cobble together sophisticated devices on a breadboard.

The hard part is the software to filter and calibrate and interpret the signals. It'd take a few hours of flying, recording the signals, and comparing to a known accurate AOA measurement method (e.g. a decent sized vane on a stick out in the freestream)


I'm not so sure one needs an accurate absolute numeric AoA, so much as a repeatable measure of how close you are to stall AoA. Such a system would need to be calibrated for each glider installation by going up and stalling in various configurations. I have some practical experience on the filtering side, including working with another poster is this group to build a flight computer with digitally differentiated variometer about a decade ago (when there was more of a need for analog circuitry). We did hours of flying (and driving fast up/down steep hills), before we managed to get the filtering right.


It is amazing the amount of processing power that's available. Here's a board with a magnetometer, 3-axis accelerometer and precision pressure sensor for under $16. The pressure sensor is calibrated for a limited range of atmospheric presssures (ground level to 500 mbar), but this is still pretty cool.

https://www.element14.com/community/...c-sensor-board
  #57  
Old April 18th 16, 09:56 PM posted to rec.aviation.soaring
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Posts: 115
Default AOA indicator

On Monday, April 18, 2016 at 1:27:39 PM UTC-7, Craig Funston wrote:
It is amazing the amount of processing power that's available. Here's a board with a magnetometer, 3-axis accelerometer and precision pressure sensor for under $16. The pressure sensor is calibrated for a limited range of atmospheric presssures (ground level to 500 mbar), but this is still pretty cool.

https://www.element14.com/community/...c-sensor-board


I use these for drone projects:

http://www.drotek.com/shop/en/home/2...0-ms5611-.html

$21 if you don't have to pay VAT. MS5611 makes a very nice variometer throughout our altitude range with proper software...
  #58  
Old April 18th 16, 10:12 PM posted to rec.aviation.soaring
Charlie M. (UH & 002 owner/pilot)
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Default AOA indicator

While this is a great idea, what happens to a pilot that flies a different glider?
I, myself, can bounce around multiple gliders in a day/weekend.

As an ex CFIG, I feel not enough training upfront to help out.

I will admit the annual numbers disagree with me.

Maybe it's a case of, "You can't fix stupid".......

Make all the rules you want, Darwin will eventually win.......
  #59  
Old April 18th 16, 10:51 PM posted to rec.aviation.soaring
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Default AOA indicator

On Monday, April 18, 2016 at 2:12:07 PM UTC-7, Charlie M. (UH & 002 owner/pilot) wrote:
While this is a great idea, what happens to a pilot that flies a different glider?
I, myself, can bounce around multiple gliders in a day/weekend.

As an ex CFIG, I feel not enough training upfront to help out.

I will admit the annual numbers disagree with me.

Maybe it's a case of, "You can't fix stupid".......

Make all the rules you want, Darwin will eventually win.......


My answer would be: the vast majority of the time for the vast majority of pilots, letting the AoA wander into the danger zone is not going to be a problem. However, after 6+ hours in the cockpit, tired, hungry, perhaps dehydrated and/or hypoxic, in gusty turbulent conditions, I've known myself to make silly mistakes. Given that I only end up doing these sorts of flights in my own glider, a little reminder about attitude might just help the one time I really need it. Over and above that, a workable AoA system would be quite helpful during winch launches.
  #60  
Old April 18th 16, 11:44 PM posted to rec.aviation.soaring
Soartech
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Default AOA indicator

On Monday, April 18, 2016 at 7:44:39 AM UTC-4, Jonathan St. Cloud wrote:
Or you could use the readily available software already developed as per the information in original post, just like Aspen did.


I just watched the video referenced in the original (first) post in this thread.
It says the software came from the Italian Aerospace Center for Research so I went to
http://www.cira.it/en/comunicazione-...zione-col-cira
and found this sentance: "The system is based on a patent-pending technology shared between CIRA and ASPEN, with four CIRA's researchers among the key inventors." So this is not "readily available software". It is patented and not available without paying for it.
 




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