Earlier, jcarlyle wrote:

2. How would he go about obtaining it? Accelerometer and frequency
counter? Stopwatch?

The latter.

I've heard that it used to be common practice to establish the
first-order symmetrical (I think) oscillation by wiggling one wingtip
up and down, and timing the cycles. If the frequency was substantially
different from that specified, it was considered cause for concern that
the wing's structure might have been compromised.

I think that this practice might have been of merit back in the says of
wooden gliders and iron pilots, but I've not heard of it considered a
standard practice for twenty years, maybe thrity. Nevil Shute wrote of
it in his autobiography _Slide Rule_.

Thanks, and best regards

Bob K.
http://www.hpaircraft.com/hp-24