Wing Frequency measuring app

And remember to do this while the fuselage is in a cradle resting firmly
on
the ground. The tire and suspension will affect the frequency.

-Tom

I would check the manual for the method used. Some manufacturers
specifically state the aircraft to be on wheel and tail skid, with tyre
pressures checked to be in a certain range. Using cradles will result in
deviations from previous methods used.

At 02:42 06 March 2016, JS wrote:
Thanks, Clyde. I know that this measurement is done at every Form Two
inspection where you live.

Until this app, the device was a mark one eyeball, and counting "one,
two,
three, (etc) while looking at some cheap watch. Then doing it again
because
you're sure you lost count! The last bit probably won't change until you
believe the app can count.
Jim


On Saturday, March 5, 2016 at 6:01:24 PM UTC-8, IA DPE wrote:
In order for this to be recorded in the aircraft logbook, it would have
to be a FAA approved measuring device, right?

While I can see some value in knowing this reading, there would have to
be standardization in the measuring device and technique I would think.

20 years ago we could take a video (including a stop watch) at the wing tip

then play it back, in slow motion if preferred. Worked perfectly and it
didn't even require a computer.

Soarin, thats a brilliant idea and so dang easy to set up and measure. All it takes is a gopro mounted to the tip with a digital clock in the background. Simply brilliant.
Dan

Eric the issue would not be in specifics but in consistence, The actual freq number isnt that important unless it is radically diff than that given for the glider as delivered. To me, its the fact that a guy should decide a method of measurment and make a measure, then repeat that exact method to see if there is change over time or after a landing or high G event.
Dan

Clyde-

Handy little App. Thanks. One suggestion: Put a 10 or 15 second delay from the time the "Start" button is pressed before counting cycles. This will allow the frequency to stabilize before starting the count.

Also, a summary page would be cool. Test time, number of beats.

Definitely worth the $0.99.

Has anyone set up their glider, then measured L and R wingtips, say 10 repetitions from dead stop and looked at the results for consistency?

Can it ever be 'normal' for the L and R wingtips to yield different measurements? How much deviation in successive measurements is acceptable?

Does temperature of the glider affect the measurement?

At 14:17 06 March 2016, wrote:
Eric the issue would not be in specifics but in consistence, The actual
fre=
q number isnt that important unless it is radically diff than that given
fo=
r the glider as delivered. To me, its the fact that a guy should decide a
m=
ethod of measurment and make a measure, then repeat that exact method to
se=
e if there is change over time or after a landing or high G event.
Dan


I think we agree on this one. That is why it is important to check which
method the manufacturer used when doing his initial measurement. Saves you
a lot of hassle...

On Saturday, 5 March 2016 08:39:05 UTC+11, 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.

Clyde.

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
Rolf

On Sunday, March 6, 2016 at 2:03:36 PM UTC-8, wrote:
On Saturday, 5 March 2016 08:39:05 UTC+11, 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.

Clyde.

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
Rolf

So can I assume before you posted that you checked every glider in existence, on every cradle imaginable, and at every tire pressure?

On my Schleicher at least, the builder has called out some very specific jacking points for this procedure.

On Monday, 7 March 2016 02:55:35 UTC+11, Mark628CA wrote:
Clyde-

Handy little App. Thanks. One suggestion: Put a 10 or 15 second delay from the time the "Start" button is pressed before counting cycles. This will allow the frequency to stabilize before starting the count.

Also, a summary page would be cool. Test time, number of beats.

Definitely worth the $0.99.

Thanks for the suggestions; I don't think the delay is necessary since it only averages over the last 20 beats. I am going to change that to a time, rather than a number of beats, since that means a wing at 100 bpm takes twice as long as one at 200 to measure. So I think I'll change it to counting the last 10 seconds or so. It calculates the standard deviation of the beat interval and announces success when that is below .02 for the sample time.

I have some other optimisation ideas to improve the performance on gliders with very flexible wings, which sometimes have a second order vibration going on at the same time.

Clyde