Help making a line launcher

[dewey-1]

A flow regulator will control the "fill" rate and be much cheaper and smaller than what dart guy is proposing.

http://www.harborfreight.com/125-psi-ai ... 68219.html

You can see one in the 3D model attached.
The overall length of this model is 36 inches.

Edit to update drawings

[ascientist]

Gun Freak
Agreed. I already have a 1.5 " diaphragm valve on the way.

dewey-1
I just plan on using a schrader valve to fill the chamber, so I don't think I will need the extra valve or a regulator to fill it. That's a great model. Any idea where to get the air tank you have shown and adapters. An all metal unit would be ideal. I'm waiting for the diaphragm valve to arrive than will be driving to various pluming stores looking for pipe and adapters. Schedule 40 2.5" PVC to fit a tennis ball will be hard to find and I would prefer light gauge metal. I may end up buying online, but am leery of making purchase without being able to pretest fit.

[dewey-1]

dewey-1
I just plan on using a schrader valve to fill the chamber, so I don't think I will need the extra valve or a regulator to fill it.

The real benifit is the small guage that is on the flow regulator.
Harbor Freight sells them cheap. You can still use a threaded Schrader valve.
You will need the gauge so you can adjust the pressures for different ranges of distances. Example: 50psi may be 400 feet, 30 psi may be 200 feet.

Also with a guage you will know if it is "armed" or not.

Check your e-mail.

[Technician1002]

Smaller launchers like that are OK for antenna launching and shorter distance line toss. They are good for a couple hundred feet. Don't expect the 1.5 inch valve variety to toss a water bottle 500+ feet.

[ascientist]

dewey-1
Now I understand. I'll pick up a flow regulator the next time I'm at Harbor Freight.

Technician1002
A solid 200' range is what I need. Being able to go beyond that would be nice, but probably not ever needed for our application. Dust collector valves or QEVs larger than 1.5" seemed expensive. Couldn't I extend the range just by lengthening the barrel with a larger air chamber? I'm still not sure what those monuments should be.

[dewey-1]

Get SCH 40 2 inch barrel (36 to 48 inches), 2 to 1-1/2 threaded bushing, a 2 inch coupling and some of these for a fun time.
Check at your local dollar stores for best prices!

[Technician1002]

If you use GGDT you can get an idea of the rough performance as it doesn't compensate for towing a line.

A longer barrel or larger chamber does not always = longer range as the barrel projectile combination is partially limited by the max flow rate of your valve. If the barrel is too long even with a huge chamber, the projectile will get a great push to get up to speed, then exceed the flow rate available through the valve and begin to slow back down to the flow rate the valve can provide into the barrel.

Using this limitation, you can optimize the chamber size and barrel length to maximize the performance of the launch while at the same time reducing the excess air lost in too large of a chamber. Larger barrel and chamber only benefit from a larger valve to provide the flow needed. A 1.5 inch diaphragm (dust collector or sprinkler) valve does have a finite limit on the max flow into the barrel.

A 2.5 inch Sched 40 will fit a stuff fit tennis ball and the Nerf footballs listed above, but won't fit pop cans or water bottles.

If you need very few or only one shot on site, a tire inflater tank works well. Keep it filled to 125PSI to be ready to go.

[ascientist]

Technician1002
Thank you I understand. I did not know about the Gas Gun Design Tool (GGDT). I'm hoping to make the barrel interchangeable, then I can experiment with several different projectiles for the throw line: weighted tennis ball, water bottle, pop can, throw bag, HighBall throw weight, etc).

I'm not sure what to expect form the from the 1.5" diaphram valve I ordered, but at least the GGDT should give me a rough idea of what dimensions I'm looking at. If you were me what valve would you go with? Again thank you. This has been a very enlightening and helpful forum.

[Technician1002]

Off the shelf, Dust collector valves perform very well based on reports of those who use them. They are designed for high gas flow. A sprinkler valve on the other hand is designed for water flow. The design does not allow for gas expansion as liquid flows through the valve and the volume does not change.

Gas flow on the other hand expands when the pressure drops through the valve, and dust collector valves geometry is optimized for this gas flow instead of liquid. They are also designed to snap open, unlike a sprinkler valve which operates slower to prevent water hammer in the pipes.

Best of course is a large diameter home made piston valve. The disadvantage with them is they can be difficult to master the construction so they are reliable. The forums here are full of piston valves that don't work right.

[jackssmirkingrevenge]

Get SCH 40 2 inch barrel (36 to 48 inches), 2 to 1-1/2 threaded bushing, a 2 inch coupling and some of these for a fun time.
Check at your local dollar stores for best prices!

Digging this up to say that this was user dewey-1's last post on this forum, ten years ago today. I believe he passed away just a few days later.

From his obituary:

When his body no longer allowed him to work on the physical projects, he still found ways to keep his mind active and share his knowledge with others. His family will always remember him as a genius.

Rest in Peace