On Tue, 17 Jan 2012 16:47:35 +0000, David Billington
wrote:

Ed Huntress wrote:
On Tue, 17 Jan 2012 18:00:56 +0700, John B.
wrote:


On Tue, 17 Jan 2012 00:16:38 -0500, Ed Huntress
wrote:


On Mon, 16 Jan 2012 18:33:28 -0800, George Plimpton
wrote:


On 1/16/2012 2:45 PM, Ed Huntress wrote:

On Mon, 16 Jan 2012 13:39:01 -0800 (PST), toolbreaker
wrote:


On Jan 16, 1:01 pm, wrote:

On Jan 16, 2:55 pm, Rich wrote:


And I wondered, why not a mile? A lot would depend on what kind of
propulsion you used, but I'm guessing the muzzle velocity would be
supersonic.

Thanks,
Rich

I am not convinced that you could propel a golf ball a mile. A golf
ball is round , which is not very good at going long distances. In
addition a golf ball is not very dense.

Dan

I ran a 3 dof ballistics program in matlab. Assuming a coef of drag
of .55 ( found on the internet) rammiping up to 1 at mach 1 the ball
traves 400 meters if I launch it at Mach 1 (330 m/sec) and 40 deg

Unless you're shooting it out of a gun, or otherwise applying a
progressive force to a full hemisphere of it, I think that the first
question is how much energy you can store in that never-very-hard mass
when you whack it with a flat object, and how much it can release on
the rebound. That may not be so easy to figure.

I don't have the math and engineering skill to do it, but it can be
done. Engineers have been doing it for some time in determining the bat
performance factor (BFP) for metal bats. It probably has been done for
a long time, but it took on more urgency once it was determined that
players were increasing the "trampoline effect" by "rolling" their bats.

Oh, yeah, I'm sure it can be done. It's not a trivial thing to
evaluate and it doubtless requires some experimental testing.

I wonder if the golf ball manufacturers have determined the limits, or
if they just limit their testing to the values they know can be
achieved by a real golfer swinging a real club.

In any case, there is a practical limit to how much energy can be
stored in one of those balls by whacking it with a club, and a lesser
(and probably diminishing as the input force increases) limit to how
much it can return by rebounding. And those limits likely are not very
much greater than the limits designed into the ball for real-world,
practical club-whacking. It seems likely that they're optimized for
that.

I believe that there is some sort of specification for golf balls, at
least those used in competition, that specifies how far they may fly
when hit with some sort of standard blow.


Aha! So they've probably done a lot of testing.

When I played golf, roughly 50 years ago, there were steel-centered
balls (cheap), which had a ball bearing in the center, and
liquid-center balls, which had a little hollow rubber sphere in the
center, about the size of a marble shooter, with a viscous liquid
inside. The centers were wrapped with a thin rubber-band material,
tight, all the way to the cover. When you cut them through with a
hacksaw the rubber bands released with a lot of force. They were
really wrapped.

Rubber can store an amazing amount of energy but it has an
extension/compression limit that's pretty sharply defined. My guess is
that the limit of rebound is somewhere around that limit.


I seem to recall seeing information about this some decades ago and the
name of the testing machine was Iron Byron, see
http://www.leaderboard.com/GLOSSARY_IRONBYRON

I'm surprised there isn't a wiki article for it.

Oh, Byron is very cool. I'll bet then that USGA has answers to the
questions raised in this thread.

--
Ed Huntress