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Re: Wind instruments get frozen and stop turning

Posted: Sat 18 Dec 2010 9:38 pm
by Synewave
Gina, you are amazing, to have done this already after only discussing it today! i look forward to the results.

Re: Wind instruments get frozen and stop turning

Posted: Sat 18 Dec 2010 10:26 pm
by Orion
Well Done
have a Christmas pudding that needs eating
look forward to seeing how you did it (pic) please

PS Anyone tried Rain x antifreeze spray

Re: Wind instruments get frozen and stop turning

Posted: Sun 19 Dec 2010 11:49 am
by Gina
Thank you chaps :) However, it is not total perfection - it isn't as free running as it was, very slight friction at one point in the rotation. Either I've got something a bit too close or it could be a whisker of glue. It's OK above a wind speed of a couple of mph but I want it as good as before. So it's coming apart again.
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Re: Wind instruments get frozen and stop turning

Posted: Sun 19 Dec 2010 12:04 pm
by Gina
Actually, I've just levered it apart a bit and it now appears quite free. It's currently running at about 6 seconds a revolution from my desk fan, on lowest speed, several feet away. I'll connect it to a tx unit shortly to check how revs equate to mph. I think it may be good enough.

Re: Wind instruments get frozen and stop turning

Posted: Sun 19 Dec 2010 2:49 pm
by Gina
Now running test system and displaying wind speed. The rotation rate of the anemometer is well below the lowest wind speed the F.O. station will measure. The wind plot below shows the initial 10rpm rotor speed then I gradually increased the "breeze" until the system changed reading. This proved to be a lot faster and at the several feet distance needed my fan turned up to 2. I then gradually reduced the air flow, until the speed where the rotor almost stopped. Finally, I turned the fan off and the rotor stopped. At it's minimum speed it was doing 3 seconds per bucket ie. 9 secs per revolution or around 6-7 rpm. This was registering minimum on gust speed and zero on average. Once the rotor stopped the gust speed also went to zero.

Conclusion :- My mod is perfectly free enough for the minimum FO wind speed. Also, the anemometer should be capable of measuring much lower wind speeds that the FO sensitivity allows (if anyone's interested in wind speeds below 1 mph).

Here is the wind speed plot in m/s - the native units for the station. Average speed in blue and gust in purple.
test-Wind-1.png

Re: Wind instruments get frozen and stop turning

Posted: Sun 19 Dec 2010 11:02 pm
by Ned
I'd be thinking about high wind speed too, when any out-of-balance caused by added skirts could be a problem.

Re: Wind instruments get frozen and stop turning

Posted: Mon 20 Dec 2010 1:08 pm
by Gina
Ned wrote:I'd be thinking about high wind speed too, when any out-of-balance caused by added skirts could be a problem.
It's already out of balance due to the magnet - I'm thinking of balancing it up. Off balance is not a problem if the anemometer is level (mast exactly upright) but...

As for heating, not doing it for the wind sensors but I think I might for my north facing webcam.
webcam2.jpeg