I'm not certain of which valve you refer to (the sprinkler valve or the shrader valve,
so I'll explain both)
The function of the sprinkler valve is to isolate the compression chamber from the
barrel, so that air can be compressed in the compression chamber. The valve is opened
(electronically; by you) when high pressure has been achieved in the compression
chamber, allowing the tennis ball to fly insane distances.
The function of the shrader valve in a tennis ball gun is identical to its function on
a bicycle tire; to allow air to flow in one direction, but not the other. In this
case, to allow air to flow into the compression chamber, but not out.
If I've lost anyone, here's a [horrid] ASCII art schematic of the contraption:
___________________
___________________|>--|
___________________ |
-{___________________>--|
Whereas the top is the barrel (a tube)
The bottom is the compression chamber (sealed by a cap on one end, and a shrader valve
epoxied through to it)
Both are connected to a doo-dad (technical term) on the end; the sprinkler valve.
Of course, since the PVC used is 3" and most sprinkler valves are 3/4 or 1 inch in
diameter, appropriate reduction hardware is necessary.
The sprinkler valves are 12 and 24 volts.. I suggest you use the 12 volt valves; fewer
batteries to tape to your gun.
--
Warren | KC0HAK
Mad Waffle #634
-----Original Message-----
From: Craig <[EMAIL PROTECTED]>
To: Warren Wu <[EMAIL PROTECTED]>
Date: Monday, April 09, 2001 10:11 PM
Subject: Re: Fwd: [RCSE] Jet-X (and Tennis Ball Cannons)
OK Warren, this sounds like a blast (literally), but I'm not clear on the details.
What's the function of the valve exactly and does it need power? Appreciate any help.
Craig.
----- Original Message -----
From: Warren Wu
To: [EMAIL PROTECTED]
Sent: Monday, April 09, 2001 3:52 PM
Subject: Re: Fwd: [RCSE] Jet-X (and Tennis Ball Cannons)
No, no, no, no, no! The way to do it is with 3" PVC pipe. Get the assorted
hardware to hook up a length of 3" PVC to a low voltage electronic sprinkler control
valve, and on the other end of the valve, build a compression chamber. This
compression chamber should have a shrader valve (like on a bicycle tire) on the other
end. Maybe a safety blow off valve, too. Get a bike tire pump and pump it to about 40
PSI and it should go about... oh, a block or so.... I've never gone higher (trying to
maintain a safety margin here...), but some of my more reckless friends have. They
warn against going above 150 PSI, and I have no reason to doubt them (in fact, I have
evidence to suggest that such a practice could be dangerous.. namely a shredded jean
leg). Make sure you glue all the parts well. If you have any doubt about the integrity
of the cannon, throw it out.
This method is a lot safer than combustibles, and you get quite a bit more
range. An advantage for me is that I can actually fire from the shoulder for better
aim. You could actually shoot it at friends if you toned it down a good bit (though
with a projectile like a tennis ball, this could be VERY DANGEROUS.)
Notes:
1) Wear safety goggles and long sleeve shirts/pants
2) Be careful
3) Put the leg of an old pair of jeans over the contraption so that if the
whole thing blows, you won't have [as much] shrapnel all over the place
4) Be careful
5) Use High Altitude tennis balls (They seem to have more oomph.. for me,
anyway)
6) Be careful
7) Anyone who knows you will certify that you're completely insane (my mother
swears I am)
8) Be careful
9) If you're so inclined, it is *possible* to shoot out a golf ball, if placed
within a proper sabot. (This is dangerous as heck, though)
10) Did I mention to be careful?
Disclaimer: I take no responsibility for an crazy actions committed with this
information.
--
Warren | KC0HAK
-----Original Message-----
From: Paul Klissner <[EMAIL PROTECTED]>
To: Alan Bangham <[EMAIL PROTECTED]>
Cc: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Date: Monday, April 09, 2001 12:06 AM
Subject: Re: Fwd: [RCSE] Jet-X (and Tennis Ball Cannons)
<SNIP>
> You forgot tennis ball cannons, marble cannons,
> and match-head starbursts. (Since the latter two are
> dangerous, I won't explain how they're made. My
> first marble cannon, I used in Mexico as a young teenager,
> and it worked. My second marble cannon I tried at home
> and shrapnel almost tore loose from it when it blew up.
> Never tried that again, lucky to not be seriously injured).
>
> I used to do those sterno/cleaner-bag UFOs, but one
> windy day scared the hell out of me that it would
> start a fire. If anyone does this, use very little
> sterno so it burns out almost immediately after launch.
> Launch in a safe place and never do it on a windy day.
>
> Tennis ball cannons were pretty safe, in so far as
> I never saw, heard of or had a mishap that even
> bordered looking like anything dangerous. Safest was
> to leave them on the ground, but we'd pick them
> up and bazooka each other with them from across
> the street.
>
>
>Tennis Ball Cannon
>
>(It used to be easier to find sturdy cans that a tennis ball
> could slip down into with a snug but easy-sliding fit. Last
> I checked Kerns juice cans were the perfect diameter. When
> I was a lot younger, Shasta soda and other sodas were in
> the correct sized cans but now they're flimsy oversized
> aluminum and won't work.).
>
>
> | |
> | | Top Can (top completely removed
> | ++ | with rotary canopener)
> |+ +| <--- Tennis ball
> | ++ |
> +----+ <--- Duct tape connects cans
> | |
> | |
> | |
> | |
> | |
> +----+ <--- Duct tape connects cans
> | |
> | |
> | |
> | |
> | |
> +----+ <--- Duct tape connects cans
> | |
> | |
> | |
> | | Bottom Can ("o" is an 1/8" punctured hole)
> | o |
> +----+
>
>At each junction where two cans connect, at the top of lower can
>of the junction and at the bottom of the upper can of the junction,
>puncture 8 triangles in a "circle" with a puncture-type can opener.
>
>The triangular holes in both surfaces of the junction line up,
>to create a channel expanding gases can eject through.
>
>Squirt a little Ronson liquid lighter fluid from a (non-pressurized)
>refill bottle into the hole in the bottom can.
>
>Hold a match to the hole protecting yourself with distance
>and angle. Thoooooop! (look up, the tennis ball is now
>100-300 ft above you).
>
>-Paul
RCSE-List facilities provided by Model Airplane News. Send "subscribe" and
"unsubscribe" requests to [EMAIL PROTECTED]
RCSE-List facilities provided by Model Airplane News. Send "subscribe" and
"unsubscribe" requests to [EMAIL PROTECTED]
