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        Discussion Got a Smartphone? - You've got an Incidence Meter!!

#1 SteveM Nov 09, 2012 06:15 PM

Got a Smartphone? - You've got an Incidence Meter!!
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Search apps for "Clinometer" or "Inclinometer".
My son was messing round with his on his phone, and noticed that it showed a reading to within 0.1 degree.
Argument developed, as I doubted that the phone sensors would be good enough to ensure sufficient consistency/accuracy.......how wrong could I be!!
I downloaded it, placed phone on granite kitchen worktop, let it settle and took a reading.
took another the next day....same to within 0.1deg.
Despite this, if checked against set square, it was found to be (albeit reproducably) 0.9 degrees out, over the 90deg rotation.
Then noticed that aswell as the free app version, there was a chargeable upgrade (50p), which allowed calibration, and the ability to zero at any angle.
Did this, followed the instructions and, sure enough, could get it to scale perfectly between 0-90deg.
Cunning plan.......carefully marked out a sheet of 1/4" balsa, and with some CF rod/plastic tube/velcro/a spring etc etc knocked up the following:-
It is extremely accurate, simple & cheap to build, nearly all of its weight sits over the LE (so does not deflect flaps/ailerons etc), and the upgrade app was the cost of a Mars bar.(although, for our purpose obviously unneccessary as we don't need 1% accuracy, but the upgrade allows us to zero on the tailplane, then the wing can easily be measured relative to this)
You may need to reduce the width of the "V's" significantly for wings which are not constant chord, otherwise, as the LE or TE are only in contact at one point, at some distance from the rod, there will be some up/down play at the other end of the V. (I am sure you can see what I mean...I had to reduce mine since pic was taken)
Give it a go...it works!!

#2 TTRotary Nov 09, 2012 10:37 PM

Very neat find and solution. Thanks much!

#3 eflightray Nov 10, 2012 07:01 AM

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But for us poor people who still rely on a baked beans can and a piece of string ;)

I needed an incidence checker in a hurry the other day to check for any twist in a wing. As the wing was flat bottomed I knocked up something quick and crude, very crude, but it did the job.

A stick, a piece of paper, a piece of wire, (actually an old bike spoke), and a rubber band. Stick the paper to the stick, poke a hole in the paper for the wire pendulum, (swing-ometer). Sorry no plans available.

The 'instrument' attached under the wing and was held in place by the rubber band over the wing.
Then moved along the wing from the center section, 1/4 span, 1/2, 3/4, and tip, and the 'swing-ometer' checked for any change. (Eyeballing just couldn't be sure).

So quick and crude, but works. (Now where do I remember hearing that before ??, but then they also called me, 'slow and........' :D

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