The pipe for the barrel is 1 1/4 in. 24 in. long. The end caps for the
projectile are 3/4 in. so there is not to much of a loose fit. I haven't
made one myself but a friend of mine has & it does just like the article
say's, use with caution & safety. I'm interested how it works with a tennis
ball, that sounds real neat. Howard K0ACF
"John Ferrell" wrote in message
...
On Fri, 27 Nov 2009 17:13:50 -0800 (PST), Gary
wrote:

On Nov 27, 11:27?am, John Ferrell wrote:
There is an artical by W4SSY in the March 2009 QST Magazine. I am
planning to duplicate it for use at my QTH. I am interested in any
comments, especially from anyone who may have already built one.

My available trees may be about 80 feet so that is my minimum
expectations!

There is a lot of Google information available but I am trying to
focus on this example.

John Ferrell W8CCW

Hi John, I have not built one yet but am contemplating. Mine will
use a Rain Bird 1" Auto Sprinkler Valve, electrically actuated (24 VAC
or DC). I plan to use a Harbor Freigth 5 in one power source for the
air compressor, the pressure gage, and the 24 VAC actuator supply.
The power source is $60-$90 depending on the sale going on, it is also
handy for lots of other stuff.

This will be my first shot because I have this available. As far as
the PVC, tire valve, fishing reel, ect. don't have that much
experience. As far as line, I have had one break on me after a nice
launch with a sling shot. Make sure your line is of good quality.
Happy launching.

Gary N4AST
I bought most of the supplies last night at Home Depot. The Orbit
sprinkler valve was only about $12. It is an inline type valve like
the one in the artical. I was thinking I would use a long piece of
pipe as the accumulator but after doing the math I have decided to go
back and get a piece of 3 inch pipe to use. BTW, the cement and primer
is available in a single package for about $6.50. I am a little
concerned about the loose fit of the projectile in the 1-1/2 inch
barrel.

I will report back as I continue.
John Ferrell W8CCW