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Wing Frequency measuring app

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Old March 7th 16, 03:27 AM posted to rec.aviation.soaring
[email protected]
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Default Wing Frequency measuring app

On Monday, 7 March 2016 09:03:36 UTC+11, wrote:

There is absolutely no difference in measured wing frequency whether done on a cradle or main / tail wheel skid or wheel. Try it out before you write otherwise. - Rolf

I have tried it out - and have seen differences. One in particular was 135 on the wheel and 141 on the cradle. That's not a huge difference, but enough to warrant a closer look, so consistency in technique will help avoid false alarms.


Old March 7th 16, 04:41 PM posted to rec.aviation.soaring
Eric Munk
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Default Wing Frequency measuring app

At 07:23 07 March 2016, Steve Thompson wrote:

Suggest instead of opinion - just use the MM for the glider.

A very good suggestion. Did a Twin Astir wing frequency check the other
week, and that was off by 5 compared to the last measurements. Turns out it
somewhat unusually should sit on its wheel and skid (12th item of the
annual checklist in the mainenance manual) not on threstles, with a
specified tyre pressure of 2.5-2.8 bar. Remeasured and it now was bang on.
The way you measure DOES matter.

Old March 7th 16, 07:11 PM posted to rec.aviation.soaring
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Default Wing Frequency measuring app

On Friday, March 4, 2016 at 4:39:05 PM UTC-5, wrote:
I have written an app that measures wing frequency - currently available for Android on the Play Store he https://play.google.com/store/apps/d...j.ios.wingfreq.

An IOS version will be available once I jump through the various hoops Apple places in the way.

Video of it in action he https://youtu.be/dBJOBxGWtCQ.


The easy and revealing part of the test, is to observe the wing tip
phase; in the first bending mode they should be synchronised within inches of each other. A wing lagging in phase would indicated spar or skin damage.
This is probably more accurate than the frequency test.
Old March 8th 16, 12:33 AM posted to rec.aviation.soaring
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Default Wing Frequency measuring app

This is a useful thread. Checking the wing resonant frequency annually, and after a bad landing, does sound a good idea, although I'm not aware that it is required at annual inspections in the USA, unless the manufacturer has specified it. My glider documentation has the factory measurement (110 per minute) resting on main wheel and tailwheel. On my check out, I was instructed to set the wings vibrating at every daily inspection, but only told to look for crinkles appearing in the wing surface, or unusual squeaking noises. I hadn't heard that the tip phase was good to look at. I'd probably buy an app for $1 if it was for the iPhone, but also I think it would be pretty easy to do accurately with a normal digital watch.

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