> A little thought here should save you the work. Besides, I doubt there's a
> centrifuge that can reach the speeds necessary to determine the failure
> point of a working valve.......
No need for a centrifuge, just need the mass of the inner part of the
core, and F=ma (a = (angular velocity)^2 * R). Measure the force needed
to depress the pin far enough to let air out of the tire (tire pressure
at 35 psi, for example) using a spring scale or load cell, plug in the
numbers and back out the angular velocity. Convert that to velocity,
and voila.
> First......the spinning forces things outward toward away from the hub.
Riiiiiiiiight...
> The spring in a Schrader valve will theoretically compress as
> rotational/centrifugal forces increase. This will not affect the seals
> ability to do its job.
Why not? If I push on the pin (away from the hub, in the direction of
centrifugal force), air comes out. Since the pin (and whatever it's
connected to) has mass, then spinning the tire at some (possibly
relativistic) speed will generate enough centrifugal force to move the
pin and bleed air.
> There are two seals that come into play here. One that seals the stem to the
> core
Not worried about the core-to-stem seal. The threaded connection
between the two will prevent relative motion between those two parts
(for this consideration, anyway). Ergo, that seal will not be affected.
> and the second seal prevents the passage of air out of the tire when
> the internal spring is not extended either by air pressure or by an object
> pressing directly on the center pin of the core. Note again that the spring
> is normally in a near relaxed state and applies very little pressure to the
> center of the core itself. Just compare the force needed to depress the
> center pin of the core when inflated and not compresses.
Exactly. I could just assume the "holding force" from pressure x area,
but actually measuring it would account for any stiction and the
miniscule spring force. Last task then is to drive out the pin and its
attached components, and weigh it on an analytical scale.
Make sense?
Krokko
--
Dr. J. Christopher Krok
John Lucas Adaptive Wind Tunnel
Caltech MS 205-45, Pasadena, CA 91125
Denis