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 ...

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 ...

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 ...

Here is a contribution sent to me by dart guy:

"if you would like to create an inline qev like thing, also you should make it so that the barrel is collapsible with screw together couplings so that it can be essentially 1' 1/2" long and as wide as the barrel. i am thinking of a thing like this.at ...

Thanks for the chart. I can't speak for water bottles or pop cans, but everything I'm finding on tennis balls indicates 2.5" schedule 40:
http://www.spudtech.com/detail.asp?id=38
http://www.antennalaunchers.com/csv19/csv19asm.html

Sounds like you have had great results with your throw line launcher ...

dewey-1
Thanks so much for your help. I ordered the ASCO FLEX KLEEN M28244 and 220 PSI Lock On Tire Inflator with Air Pressure Gauge Pistol Chuck Flexible Hose.

This okay?

http://www.ebay.com/itm/ASCO-DIAPHRAGM- ... vi-content

What would you recommend for triggering this valve?

dewey-1
Thanks for the links. Would 3 inch be a little overkill for a portable launcher? The price is very tempting.

Technician1002
I may be confused, but I thought schedule 40 was thinner than 80. At any rate I understand - use the thin wall for tennis balls.

I'll have to look into whether I can find a fire extinguisher. Thanks for the valve recommendation. When I have some time I will price shop and buy that one. Do you recommend the same trigger setup as shown in your link?

So should I just go with a 2" sprinkler valve? I've not been able to find a good size dust collector valve or QEV for a reasonable price.

Technician1002
Dynema is very low stretch, so I'll have to keep braided mason line in mind. Water bottle and tennis ball comparability sounds great with 2.5" schedule 40 PVC. I think that excludes a coaxial build. Thanks for the advise.

Great! Water bottle sounds like the way to go. I also like the second water bottle as an anchor. Thanks for sharing. Any particular brand water bottle you recommend? Mason line would be cheaper, but I really like the strength and slickness of Dynema throw line.

Would you recommend this valve?
http://www.ebay.com/itm/Asco-JFK8353J39 ... 43be7950a8
I'm all for just buying a valve, but am having a hard time finding/identifying an appropriate one for purchase.

qwerty
They make something like that for the slingshot launcher: http://www.sherrilltree.com/Professional-Gear/BIGshot/Big-Shot-Line-Reel It is used to pull a second larger line that is then used to pull the rope. Rope with friction can require a good deal of pull, so throw line about the thickness ...

That's the idea. No way we will be able to launch our 11mm rope very far. The throw line we use is about. The throw line we use is about as thick as masonry string line sold at hardware stores, but made of spectra so it is smother and several times stronger.