Re: SA's latest issue

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>

>
> Pardon my intrusion, but the Shumann resonance seems to ring a bell about
> Inertial Navigation Systems. I am not really acquainted with these
systems,
> but I recall that this resonance or pendulum effect is included in their
> navigation calculations. Don't rate gyros experience this effect?
> I also recall vaguely that Tesla worked out some very low earth resonant
> frequency based on his observations of lightning in Colorado.

You're thinking of Schuler tuning for pendulums...

from
www.timezone-dot-com/WebPages/Features/TZEssays/WaltArnstein/Pendulum_2.html

A useful form of pendulum is the Schuler pendulum. To gain an insight into
its usefulness, consider the problem of maintaining a horizontal platform in
flight. Let's assume there is no GPS, no celestial navigation to help us,
how can we keep the floor beneath us horizontal? One way would be to track
the local vertical. If we hung a pendulum from our vehicle and started from
a stop, the pendulum would tend to follow the local vertical. Of course,
every time we accelerated and reached a new speed or direction, the pendulum
would swing and we would have a vertical that oscillated about the true
vertical. The magnitude and frequency of oscillation would vary with the
length of the pendulum. The longer the pendulum, the lower the magnitude and
frequency of its oscillation. So, we might ask ourselves, is there any
length of pendulum that would track the vertical without starting to
oscillate? The answer is yes: It would be a pendulum equal in length to our
distance from the center of the Earth. This is called a Schuler pendulum and
its characteristic would be that as we accelerated forward, it would swing
backward in reaction in such a way that the vertical would always be
maintained.


from http://roland.lerc.nasa.gov/~dglover/dictionary//s.html
Schuler pendulum:
A hypothetical pendulum with a period of 84 minutes.
A simulated Schuler pendulum carried in a vehicle moving in the earth's
gravitational field would always indicate the true vertical.
Schuler tuning
Adjusting a system performing the function of a pendulum so that is has a
period of 84 minutes. See Schuler pendulum.