OpenxVario Air Speed Sensor - Add on

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DHDSP
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Re: OpenxVario Air Speed Sensor - Add on

Post by DHDSP » Sun Mar 24, 2013 3:26 pm

Kilrah wrote:You still need a wire to power it, so why not run the data through it?
I'm not really sure, on those bigger model planes some people have smoke-gizmos at the wingtip. So it should be possible to have a small battery there.
But maybe you're right, a thin wire would probably work too ;)


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Re: OpenxVario Air Speed Sensor - Add on

Post by jhsa » Tue Mar 26, 2013 10:24 am

jhsa wrote:here is why airspeed is so important.. forget the AoA. If you don't have enough airspeed....... :o

[BBvideo 425,350]https://www.youtube.com/watch?v=zxbulrrQVig[/BBvideo]

I posted the video above some days ago, and just came across with this page today by coincidence..

http://www.dailymail.co.uk/news/article ... unway.html

It's good to know that the pilot fully recovered and he crawled away from the aircraft on his own..
Apart from that great photography job..
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Re: OpenxVario Air Speed Sensor - Add on

Post by Flaps 30 » Tue Mar 26, 2013 12:39 pm

Yes that is a great example of how to screw up. It is also a good demonstration of how important the AoA is to staying in the air. :)

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Re: OpenxVario Air Speed Sensor - Add on

Post by jhsa » Tue Mar 26, 2013 12:42 pm

yep. keep your speed and it won't happen.. :D
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Re: OpenxVario Air Speed Sensor - Add on

Post by Cerberus » Thu Apr 25, 2013 12:11 am

Is it somebody working on this add or not?
I ordered Air Speed Sensor from Eagle Trees Systems (It will take few days to receive it) and I will try to implement it to the Arduino Vario. But if somebody is working on it, just let me to know. Also is there any specific/preferred ID address in the Frsky or Open 9X for Air Speed in the serial data stream?


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Re: OpenxVario Air Speed Sensor - Add on

Post by tilmanb » Thu Apr 25, 2013 9:10 am

No, this thread is as far as we got. :)

There is a field in the sensor hub protocol for speed. It is from the GPS module and would usually measure ground speed.

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Re: OpenxVario Air Speed Sensor - Add on

Post by Rob Thomson » Thu Apr 25, 2013 12:33 pm

I came to the conclusion I did not want to mount such large sensor on any of my models :-)

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Re: OpenxVario Air Speed Sensor - Add on

Post by rainer » Thu Apr 25, 2013 4:47 pm

Sorry i didn't have much time lately, so no progress from me as well
build your own vario ==> https://github.com/openXsensor/openXsensor/wiki (Formerly https://code.google.com/p/openxsensor/ and https://code.google.com/p/openxvario/)

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Re: OpenxVario Air Speed Sensor - Add on

Post by Cerberus » Thu Apr 25, 2013 6:46 pm

No worries, when I receive it I will try do something and you can test the code withing vario to aprove using the Arduino code. So for ID should I use the GPS_SPEED_A 0x19, or we can add specific IF forAir Speed to The System?

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Re: OpenxVario Air Speed Sensor - Add on

Post by rainer » Thu Apr 25, 2013 7:07 pm

I would go for 0x19. the chance that somebody wants to use two different speed values for one plane in parallel is rather small.
build your own vario ==> https://github.com/openXsensor/openXsensor/wiki (Formerly https://code.google.com/p/openxsensor/ and https://code.google.com/p/openxvario/)

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Re: OpenxVario Air Speed Sensor - Add on

Post by Cerberus » Thu Apr 25, 2013 8:32 pm

OK, Thanks.

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Re: OpenxVario Air Speed Sensor - Add on

Post by Romolo » Sat May 11, 2013 6:09 pm

A good reason for adding a true air speed sensor to openxvario is to have a compensated, total energy vario as well.
you need: static probe connected to differential and absolute sensor, dynamic probe connected to differential.

Then we need some math to calculate potential and kinetic energy.
The sum of the two is a decreasing function of time (due to efficiency less than 1 of the plane).

But what is relevant is that with the two values you can understand if you are in a thumb thermal or in a true thermal

in a thumb thermal you will decrease kinetic energy and you will increase potential one..
in a real thermal you will get potential energy without loosing kinetic one.

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Re: OpenxVario Air Speed Sensor - Add on

Post by rainer » Sat May 11, 2013 7:55 pm

If you want to use an airspeed sensor with an output linear voltage relative to the airspeed, thats quite easy to implement. i would just have to find out how to transfer airspeed to the opentx. the rest could be copied over form the current sensor code.

Getting a TEC vario out of it would be a bit more complicated due to the way the sensors output their data ( e.g. delay/ filtering/-...)
it would require a lot of test flying / development to fine tune these algorythms. the currently used MS5611 is in my opinion not usable combined with a speed sensor that has different characteristics. energy compensation would be much easier and create better results using a well tuned tec tube.
The current implementaiton of the MS5611 in the oXv has very specific behaviour not allways generating data usable for a tec algorythm. The kalman filter is nice for thermal detection in normal situation but shows bigger delays on high vertical speeds that tend to take some seconds before they stop influencing the actual vertical speed calculation.
e.g. if i start my dlg, i get very high ascend speeds. once i push at the top point, it takes the vario another couple of seconds before it will show a stable situation again.
Still for normal flight the output is great, but this kinds of effects will make it really hard to try to calculate an enegy compensation.
we would have to experimet with other filters that will show different effects in other situations.

And then we would aslso have a second sensor/filter compensation for the air speed sensor... the best way to develop something like this would probably to first write some kind of simulator and do most of the test flying virtual. but this amount of time is currently not available for me.
build your own vario ==> https://github.com/openXsensor/openXsensor/wiki (Formerly https://code.google.com/p/openxsensor/ and https://code.google.com/p/openxvario/)

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Re: OpenxVario Air Speed Sensor - Add on

Post by tedbmoss » Tue Sep 17, 2013 5:07 am

I got one of the airspeed kits from 3D Robotics with mpxv7002dp sensor, I think it would be a good place to start since it has pitot tubes and is ready to use.

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Re: OpenxVario Air Speed Sensor - Add on

Post by RightRudder » Mon Oct 14, 2013 9:40 pm

I had talked about much more sensitive sensors in another thread.

http://openrcforums.com/forum/viewtopic.php?f=86&t=2889


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