Sam Smith Has built the biggest GIT to date! Both "Bowling Ball Bertha" and "billiard ball billy" are detailed.
Sam Smith, a communicator extrordinaire, has been in contact with me from nearly the beginning. He undertook a Large project called "Bowling Ball Bertha" a while back. Here is the report on his efforts.
This is the email I received (DavidC) on the 6th of September 1997:
David:
You guys awake? Turn on the e-mail....
NEWS FLASH! NEWS FLASH! NEWS FLASH! NEWS FLASH! NEWS FLASH! NEWS FLASH!
(All wires)
At 8:32 PM Eastern Time today a new Outdoor World's Land Speed &
Endurance Record for GIT-powered automotives was set in the small town
of Anthony, Florida, USA.
Sporting a garish red racing numeral "1", "Bowling Ball Bertha"
trundeled her way into the record books with a blistering performance of
almost three feet, three inches from a standing start in something under
12 seconds flat.
Bystanders were enthralled as the electric-powered gyroscopic
inertial propulsion mechanism was given the gun. Seven spectrally mis-
matched bowling balls suddenly began to accellerate around an enclosed
track,their inital slow rotation growing in moments to a bluring rainbow
as the hurtling spheroids gained momentum.
Whining and shuddering, the incredible conveyance described an
erratic path as the operator, Mr. S. Smith, pulled desperately on the
guide rein and the power control, vainly trying to harness the almost
uncontrollable power and ferocity of the untamed mechanism.
Within moments, it became clear that the unguided castor-wheel
suspension, but lately transferred from a derelict shopping cart, could
not be controlled adequately to guarantee the safety of the cheering
bystanders, and the device was reluctantly shut down.
As it whirled to a stop, a witness was heard to say : "Wow! That's
just like 'Back to the Future'!". Others proclaimed the device incredible,
and still others commented that the operator was clearly mad.
But, of course, in only the very best way.
Our correspondent will be on hand for continuing trials scheduled
for the following day, when a new and more powerful motor will be installed
atop the device, and it's suspension modified to eliminate all trace of
maneuverability.
Said the Operator, Mr. Smith: "This is a straight-line Speed
Machine--it doesn't need to turn!"
End trans
(No thirty)
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Damn! That was fun! Burned out the motor, though. More tomorrow!
Sam
!Got some GOOD pics! Wait'll ya SEE!
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As you can see from the photos, Bertha is a bit of a monster! The wood lever is a 2 by 4 to pull tension on the belt as a simple clutch.
Another Project Sam put together (a little more reasonably sized) is "billiard ball billy", made from billiard balls, a couple of sponge cake pans, and a pulley for the drive wheel.
What follows is some of Sam's thoughts on both billy and Bertha in a letter I received on the 7th of September (edited for relevant content):
I have learned a lot from building Bertha, most particularly that the
ring race placement and angle factors are critical.
Skidding is the weakness of the spherical-mass friction type GIT. As the
angle of contact changes toward the vertical (at the tail) the spheroid
is most likely to skid rather than roll.
Get hustled along by the Drive Wheel, as it were.
At the Nose, the angle of contact is almost directly through the center
of mass, and even at the greater speed, there is less tendancy to skid.
What apparently happens is that spheres skid and "speed-up" in the tail,
and begin to overtake the theoretical front of the pack. This causes
clustering of several balls on one side of the track, which changes the
load geometry on the drive wheel, causing it to buck minutely sideways,
decreasing drive efficency, increasing skidding, and allowing
overrunning of the Drive Wheel, as well.
All that contributes to creating & maintaining an unbalanced rotational
mass, so the GIT acts like a washing machine doing the well-known
"overload hula". It tends to whirl and "hunt" for a direction to go.
Back to Billiard Ball Bill.
I've built & tested a small GIT made from cake pans and billiard balls.
The design & construction are unbelievably sweet: simple, self-jigging,
accurate. No machining or welding. No tooling at all. Building bbb takes
maybe three hours from scratch.
Total cost about $35.00. It requires very few tools, and no great skill.
My workspace was a TV tray.
Billiard Ball Bill is an ideal kit-candidate (In fact, the kit's
already written--it's about five pages long), except that it doesn't
motivate worth a damn. Note of 22 May 1998: Plans for the new improved (with the all important race traction added) "billiard ball billy" run 15 pages now completed and available) DavidC
The skidding and clustering are very evident in the bare-metal/ billiard
ball version I built.
Now, that can probably be fixed in the small GIT: I have modifications
in mind for a traction-layer on drive wheel & rings, and one for
substituting hard-rubber balls.
Problem is, the clustering that plagues the bare-metal version of bbb is
a major weakness in BBB, as well. And I'm not at all sure that something
like a traction-layer fix would be effective. Effective as in the
reliable-functional sense.
The problem is that BBB is rather powerful--when it starts to hula,
somebody could get hurt quick. It could sink a canoe pronto, for
example.
BBB is a bit of a dreadnought, considering she porks in at almost 200 lbs.
I'm seriously wondering if BBB should be retired rather than kitted out.
---------- edited personal communications (DC)----------
On the other hand, a double-conic is almost certain to be much less
skid-prone simply because the angle of contact is constant at all
positions around the split track.
I think I can have a small GIT kit out fairly soon. One that actually
works (imagine THAT!). I mean, you can't hardly give someone their
money's worth with something that doesn't work in the first place, and
that also makes it a rather poor candidate for the Science Project
market.
And I was SO looking forward to getting the educational market....
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Sam goes on to discuss his kit plans, and personal communications that I'm not going to share with you. He's had a lot of out of town business to take care of, so the GIT testing is stalled for a while on his end, but check back here on Sam's page for his updates, and hopefully soon a set of plans or two you can purchace from him to make your own tested and proven GIT.
Addition of 29 September 1997 - Sam Got a preview of his page before the rest of you (it was on the site, just not linked in :), and he sent a update report on billy's first swim, pasted in here below:
Shazaaaaayum! bbb has gone for his first swim. Well, boat-ride,
actually. I placed an Action Packer (a large plastic packing box--very
excellent product, available from Wal-mart for $18, or so) in the
bathtub with enough water to float, and put bbb inside, on center.
The bbb GIT-ling is powered by an electric hand drill at the moment
(just the thing for drilling electric hands), and when I spun it up it
showed an instant interest in moseying along the length of the bathtub.
About 15 seconds, end to end, with a slight tendancy to steer N by NW since bbb
wasn't quite perfectly aligned with the length of the Action Packer.
Being rectangular, the "boat" would have a slight straight-ahead
ruddering effect, but I'd say bbb is putting out maybe a clean two to
three ounces of true thrust.
Enough to successfully demo, in the real world, and doubling up the
power with a little better motor should bring it up to a spritely
half-lb or so of thrust, which would be ducky-plenty for all kinds of
dry-land wheeling about.
(Today the bath-tub, tomorrow the World, Pinky!)
Call that one an empirical succcess, though not with an accurately
measured output.
You'da laughed, though: I tried it first with a cookie sheet--which has
about a half-inch of freeboard, unloaded. Add one bbb, and you get about
-1/16" of freeboard. So, maybe it WAS a swim, after all, although the
lifeguard was on duty, so nothing got too wet.
By the way, you were also right about the slight rotation on spinup. The
Action Packer turned a bit, and bumped a corner firmly on the side of
the tub.
I've only got about three minutes running-time on the new rubber track
linings, but they seem to be holding up just fine. (So far.) Ditto for
the wheel lining, which I would expect to be 'way more durable, anyhow.
Write Sam directly at Sam Smith (ldmorgan@digital.net).
Plans are now available (beginning Monday October 6th) for "billiard ball billy", the Price is $15.00 US, money orders only, which includes everything including postage, and will ship within 2 working days.
The kit includes "full step-by-step instructions with drawings & photos, a full Bill of Materials, Tools Required, Helpful Hints, and a complete explaination of the friction-driven GIT. Etc. All written to be understandable by regular humans--like us." (and that's a quote! - DavidC).
Write to (and make money orders payable to): Sam Smith PO Box 317 Anthony, Florida 32617
PS: In case you were wondering, "Lord Morgan" is the
name of a colorful persona well known to many members of the Society For
Creative Anachronism--interesting individuals who re-create and re-live
the better parts of the Middle Ages. "Lord Morgan" is a bard, poet,
merchant, and jeweller, and the proprietor of "Jolly Sven's Bargain
Pillage". His motto is "Caveat Temptor!".
Stay tuned! - DavidC - 2 am, Tuesday, 1 October 1997
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