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Antenna Launching with a Tennis Ball Air-Gun
Compressed air is pumped into a PVC air-gun structure
Launching antennas into trees can be a challenging and time consuming effort for portable deployments. One solution many have found safe and workable is launching a tennis ball over a tree with compressed air. A (mostly) PVC structure is built. The primary elements are:
- Air chamber for storing compressed air
- Barrel from which to fire the tennis ball
- Air pressure gauge (80 pounds pressure worked well, but it has been fired at up to 120 pounds air pressure)
- Fast-action air value (the most critical and difficult to find component)
- Ramrod to properly seat the tennis ball
- Fishing reel (open faced is recommended)
- Air compressor (bicycle hand pump or car tire pump; manual or 12-vdc)
- Launching line
- High-test fishing line
- Light-weight, high-test, 1/8-inch rope (approx. 3-times as long as the tree limb over which you are planning to shoot)
- Light antenna line, such as Silky Wire (1,000-feet weighs less than 16-oz.) may be used directly, eliminating the fishing line and 1/8" rope. However, you do have to properly prepare the antenna wire to ensure it remains free of tangles. One solution is to wind it back and forth on a tarp (keeping it free of grass and stick snags).
Here some links to get you started:
- By wb6zqz The smaller one is very similar to what we used.
- By WD6CMU This is a monster!
- Trident Another monster!
- By WØEB A couple "action shots" but no construction details
This is the tennis ball launching air-gun.
Home-brewed, of course, following in the footsteps of others that have perfected the design to its current state.
These are most of the implements needed.
The silver object on the left is a battery powered car tire pump.
Address your target.
This is where you visualize the successful result of your shot
Aim high, and take account of the wind direction and speed.
Ensure your landing area is clear!
It is thought the terminal velocity of the tennis ball returning to earth will too slow to actually hurt a person, it may still scare the daylights out of them if they are not expecting it, as well as cause other collateral damage, such as broken dishes or windows.
This is a closer look at the tennis ball launcher.
Be prepared to grab the line and yank!
When you see how the wind is affecting it,
you may wish to cut the flight short.
Note the loop of fishing line that has been secured inside the tennis ball. What you can't see is the sand/BBs for weight and the silicone cement used to seal up the slit in the tennis ball. The longer fishing line is tied to this loop. If you have to retrieve the fishing line it is best to cut the line. If you try to haul that tennis ball back through the tree it will get stuck.
Once you have shot the fishing line over the tree limb, tie a light-weight rope to the fishing line (a bowline is suggested).
Then reel the fishing line back in, pulling the rope over the tree limb and back to your shooting position. Then tie your antenna wire to the wire and use the rope to pull the antenna wire up into the tree.
Playing a flute is optional.
Can you see the fishing line?
I just liked the clouds in this shot. It also suggests the height of this tree, which I estimate to be over 100-feet tall. The limb damage visible in some of the above pictures were from the severe ice storm in February 2007. A front sat on us and essentially hit us with three waves of ice storms in a row. It took all three to damage my trees. I was sad. But while many branches were lost, it appears all my trees will recover and live out a long and fruitful life of supporting Strange Antennas for years to come!