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.

3 9V batteries in series makes a fine source to actuate a sprinkler
valve. Put a 0.1 uf (or thereabouts, non critical) capacitor across the
pushbutton contacts to make it last a bit longer.


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

On Mon, 30 Nov 2009 10:31:12 -0800, Jim Lux
wrote:



3 9V batteries in series makes a fine source to actuate a sprinkler
valve. Put a 0.1 uf (or thereabouts, non critical) capacitor across the
pushbutton contacts to make it last a bit longer.

Got a little further today. It takes too many hands to twist the
valve, fiddle with the reel and aim the device. I black vinyl taped a
micro switch to the valve assembly with ONE 9 volt battery so that I
can thumb it to launch. I also moved the open face reel back to the
valve end of the barrel and fabricated (more black tape & paperclip)
an eye to pass the line through so that line retrieval with the reel
is less awkward. Today's final test was conducted in the dark so I was
unable to see much. I launched nearly 90 degrees and it was gone for
several seconds so I expect it did well.

VK2KC emailed me with some advice. He pointed out that it is usually
better to launch from the woods to an open space. I expect that will
be the case.

It seems to me that this device consists of three components: Barrel,
Valve and accumulator. It seems that to change to launching tennis
balls would be a matter of fitting a 2-1/2" barrel. I doubt that I am
going to find that in my area but I will keep my eyes open.

Tomorrow is another day!

John Ferrell W8CCW

John Ferrell wrote in
:

On Mon, 30 Nov 2009 10:31:12 -0800, Jim Lux
wrote:



3 9V batteries in series makes a fine source to actuate a sprinkler
valve. Put a 0.1 uf (or thereabouts, non critical) capacitor across the
pushbutton contacts to make it last a bit longer.

Got a little further today. It takes too many hands to twist the
valve, fiddle with the reel and aim the device. I black vinyl taped a
micro switch to the valve assembly with ONE 9 volt battery so that I
can thumb it to launch. I also moved the open face reel back to the
valve end of the barrel and fabricated (more black tape & paperclip)
an eye to pass the line through so that line retrieval with the reel
is less awkward. Today's final test was conducted in the dark so I was
unable to see much. I launched nearly 90 degrees and it was gone for
several seconds so I expect it did well.

VK2KC emailed me with some advice. He pointed out that it is usually
better to launch from the woods to an open space. I expect that will
be the case.

It seems to me that this device consists of three components: Barrel,
Valve and accumulator. It seems that to change to launching tennis
balls would be a matter of fitting a 2-1/2" barrel. I doubt that I am
going to find that in my area but I will keep my eyes open.

Tomorrow is another day!

John Ferrell W8CCW


Sorry if my post is as silly as it appears it might be, but just in case it
isn't... I've seen people walking dogs in a large park I run in a lot. They
have these slingshot/stick type affairs to throw tennis balls with for fast
strong dogs to get a lot of exercise fetching them while the owner has an
easier time of it. I've never tried one, but from what I've seen, even
unconscious practise seems to result in some accuracy, and distance certainly
isn't lacking. In short, it might be easier, cheaper and faster to practise
with one of those than to devise a more complex launcher. It seems to me that
accurately placing a thin line over a branch up to 100 ft high might be
easier than learning to fly-cast.

Another thing I remember, on a smaller scale by far, is a small stick and two
rubber bands, one binding the other over the end of the stick. I was about 6,
at a strange house competing with another boy to accurately and strongly
catapult nasturtium seeds by releasing them against the stick so the band
drew them near-parallel to it at speed. It's very effective because it eases
aiming and the recoil is just enough to cause the stick end to slew aside to
allow accurate clearance at the crucial instant, something that became
immediately apparent at the time I 'invented' it. If the thing were scaled
up, for example with a carefully prepared inner tube from a cycle tyre, then
maybe the thing can launch a weighted tennis ball and light line accurately
with one shot. The trial and error would certainly be a lot lower than the
dog-ball-slinger.

On Wed, 02 Dec 2009 03:04:48 -0600, Lostgallifreyan
wrote:


Sorry if my post is as silly as it appears it might be, but just in case it
isn't... I've seen people walking dogs in a large park I run in a lot. They
have these slingshot/stick type affairs to throw tennis balls with for fast
strong dogs to get a lot of exercise fetching them while the owner has an
easier time of it. I've never tried one, but from what I've seen, even
unconscious practise seems to result in some accuracy, and distance certainly
isn't lacking. In short, it might be easier, cheaper and faster to practise
with one of those than to devise a more complex launcher. It seems to me that
accurately placing a thin line over a branch up to 100 ft high might be
easier than learning to fly-cast.

Another thing I remember, on a smaller scale by far, is a small stick and two
rubber bands, one binding the other over the end of the stick. I was about 6,
at a strange house competing with another boy to accurately and strongly
catapult nasturtium seeds by releasing them against the stick so the band
drew them near-parallel to it at speed. It's very effective because it eases
aiming and the recoil is just enough to cause the stick end to slew aside to
allow accurate clearance at the crucial instant, something that became
immediately apparent at the time I 'invented' it. If the thing were scaled
up, for example with a carefully prepared inner tube from a cycle tyre, then
maybe the thing can launch a weighted tennis ball and light line accurately
with one shot. The trial and error would certainly be a lot lower than the
dog-ball-slinger.

I am still open to all leads. I did a Google on "dog ball shooter" and
found a lot of interesting posts. I don't think any of them are up to
carrying a monofilament line over a 100 foot tree but they are still
interesting. My Black Lab enjoys chasing a genuine bowling pin when I
throw it but we are both getting too old for that game! It has given
her very strong neck muscles.

The Hyper dog launcher looks to be effective and inexpensive for the
intended purpose.

I met a fellow at Home Depot that does a lot of surf fishing in the
ocean. He is considering a similar device as my launcher to place his
bait further from the beach...

Rainy day (flood warnings) in North Carolina today... antenna play on
computer today.

John Ferrell W8CCW

John Ferrell wrote in
:

I am still open to all leads. I did a Google on "dog ball shooter" and
found a lot of interesting posts. I don't think any of them are up to
carrying a monofilament line over a 100 foot tree but they are still
interesting. My Black Lab enjoys chasing a genuine bowling pin when I
throw it but we are both getting too old for that game! It has given
her very strong neck muscles.

The Hyper dog launcher looks to be effective and inexpensive for the
intended purpose.

I met a fellow at Home Depot that does a lot of surf fishing in the
ocean. He is considering a similar device as my launcher to place his
bait further from the beach...

Rainy day (flood warnings) in North Carolina today... antenna play on
computer today.

John Ferrell W8CCW


One thing I didn't catch was how often you might need to relaunch.. If lots,
then for consistency your gadget will win easily. I'd still try the inner-
tube elastic and 3 foot stick wheeze though. I also tried making bows and
arrows as a kid and was hopeless, but the straight-stick catapult really
scored.. (I'm surrounded by 4-floor buildings though so this is sort of
rhetorical, I couldn't actually do it on anything but a short trajectory to
ground here without breaking something).

John Ferrell wrote:
On Mon, 30 Nov 2009 10:31:12 -0800, Jim Lux
wrote:


3 9V batteries in series makes a fine source to actuate a sprinkler
valve. Put a 0.1 uf (or thereabouts, non critical) capacitor across the
pushbutton contacts to make it last a bit longer.

Got a little further today. It takes too many hands to twist the
valve, fiddle with the reel and aim the device. I black vinyl taped a
micro switch to the valve assembly with ONE 9 volt battery so that I
can thumb it to launch. I also moved the open face reel back to the
valve end of the barrel and fabricated (more black tape & paperclip)
an eye to pass the line through so that line retrieval with the reel
is less awkward. Today's final test was conducted in the dark so I was
unable to see much. I launched nearly 90 degrees and it was gone for
several seconds so I expect it did well.

I've found that a single 9V will open a valve if there's not much
pressure, the coil is cool, etc. Run the pressure up, grab the thing
out of the back of the car where it's been cooking in the sun, etc. and
a bit more current through the coil is handy. (Oh yeah, and with 3
alkaline 9Vs, they'll last basically forever, because it will still fire
when they're almost dead... use the ones you pulled out of your smoke
alarms at home)


VK2KC emailed me with some advice. He pointed out that it is usually
better to launch from the woods to an open space. I expect that will
be the case.

It seems to me that this device consists of three components: Barrel,
Valve and accumulator. It seems that to change to launching tennis
balls would be a matter of fitting a 2-1/2" barrel. I doubt that I am
going to find that in my area but I will keep my eyes open.

Don't neglect the possibility of using a slightly large barrel with a
liner (take a bigger diameter piece of plastic pipe, use a circular saw
to rip a slot down the length, and then squeeze it down to fit inside
the outer tube.

Or a sabot/piston made of closed cell foam (e.g. cut a disc of styrofoam
that fits snugly.. or I like polyethylene foam.. it's a bit springier)

Or, use one of those squishy fairly dense foam rubber balls (you see
them as "stress relievers" as a giveaway at trade show booths, for
instance) that are available in a variety of sizes and make a snug fit
with the ID of whatever barrel you use.



Tomorrow is another day!

John Ferrell W8CCW