Help making a line launcher

[ascientist]

I'm on the rope rescue team of my local search and rescue. There are situations in which we need to get a rope high in a tree or across a river. Currently we have two people hold ether side of a sort of large slingshot while a third person launches a weighted bag attached to a throw line. The throw line is then used to pull the full size rope. This method has a distance limited to only about 70 vertical feet and 150 horizontal feet. http://www.sherrilltree.com/Professiona ... ent-Tubing

We don't have the funds to buy one of the commercial grade CO2 rope launchers. Also If I build it I can uses it for other launching activities:)

I found that radio folks were using air launchers to shoot line up trees using weighted tennis balls: http://www.akbeng.com/products/antenna-launchers/

I am hoping to make something better. I'm not set on using tennis balls, but will need something I can attach the throw line to. Normal throw bags would be hard to get a decent seal. I considered this: http://www.sherrilltree.com/Professiona ... eight-10oz but worry the ribber will cause to much drag through the barrel.

When I was a kid I made a simple ball valve spud gun that worked great, but it used about 30 feet of 2” PVC so was not very portable. From what I've read so so far I sounds like I want to make a coaxial with a piston valve. Perhaps like this: but with 4” pipe rather than 3”. I still plan on using spectra throw line and would like to have at least a 300' horizontal range.

I'm sorry to be another noob asking for a design. I have searched the forum, but am still looking for direction. In particular I'm having trouble finding a valve design I think I can reproduce. Also wondered if I should do this in ABS rather than PVC for the crack versus shatter argument. Thanks

[jackssmirkingrevenge]

A noble cause, what's your budget?

[ToasT]

A metered combustion cannon may give you a slightly more portable launcher as there is no need for a pump, which could be important for a search and rescue team?
It may tread on more laws than a pneumatic though, depending on where you are.

[Gun Freak]

Using tennis balls to attach the line to would create an inherently large cannon which I don't think you want. A coaxial or over-under golf ball gun (or 1.5" pvc bore max) would probably be optimal, although you could possibly get around with a 2" bore. You're gonna want to launch something of considerable mass so that it doesn't get slowed down by the drag induced by the line, but I'm sure you know that already considering you've used a launcher for this purpose already.

Like toast said, you could go with a metered combustion for portability, but if you wanna go pneumatic like all the cool kids are doing, you could make a luncher that is just as portable that is powered by an HPA tank, albeit more expensive and you'd likely get less shots.

Coaxials get a little more difficult to make at this large of a size, so your best bet would probably be a 2" piston valve. They are fairly common around here so you can look around for examples and tutorials.

[ascientist]

jackssmirkingrevenge
300.00 maximum for the budget. Less is better as it is coming out of my own pocket.

ToasT
I agree that combustion would be more portable. I'm wanting to go the pneumatic rout. We don't have to follow OSHA guidelines or anything, but I doubt the sheriff we're under would let it fly. Pneumatic is already pushing it. By the time they have called out the rope team for a rescue that requires something like traversing a river we are hauling enough gear that an extra 20 lbs is not usually a deal breaker. Now if were doing a mountain rescue that's a 10 mile hike in, this is not going to be taken no matter how small.

Gun Freak
So I'm going to be looking for a tennis ball alternative that works in a 1.5” or 2” boar. That way I can stick with a 3” rather than 4” pressure chamber. I like the idea of coaxial as space in our gear trailer is limited. HPA sounds good, but it's not something I've ever worked with, so am hesitant. Also it is hard to say how many shots we would need.

[Brian the brain]

You could launch a thin, lightweight wire first, to pull the actual rope along after.

This will eliminate the need for a large launcher.

[ascientist]

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.

[qwerty]

Surely something simple enough as an inline PVC ball valve launcher would suffice? The barrel could be detachable and would clip onto the chamber using another bit of PVC with a section cut out of it.
Would it be possible to just use some high weight sea fishing line and then you could use a cheap fishing reel to hold the line?
For multiple shits you could just attach a bike pump in the same way as as the barrel.

[ascientist]

qwerty
They make something like that for the slingshot launcher: http://www.sherrilltree.com/Professiona ... -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 of a shoe lace is ideal. I was planning on just using a ball valve until I learned there was a community out there that had turned making these things into an art form. Everyone seems to talk down the simple ball valve, but I also wonder if it might not be good enough.

[Brian the brain]

You might as well use a dustcollector valve or QEV....or, if you can , make a piston valve.
Better performance and better consistancy.

[ascientist]

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.

[Technician1002]

In field testing for longer distances, I found water bottles works much better than tennis balls when towing 500 feet of mason line. To prevent snap back, I found tying the bitter end of the line to a second water bottle so when the line is fully deployed, the 2nd bottle is lifted, carried about 30-50 feet, then settles while arresting the launched bottle so it slows forward motion and then falls to the ground with the line fully deployed. This was key at a ham-fast for a launch over 2 Douglass fir trees to span a field with an aerial.



Cleared the tree tops and dropped the line over the tops

Early test with kite string was a failure as the line tangles easily. Mason line dropped in a figure 8 on the ground to pay out works best. No tangles and no drag payout.

Would you recommend this valve?

In the field I do not recommend electric valves. Get one that is air piloted instead.
Some electric valves can be converted by removing the solenoid and using a strong ring magnet over the core to trip it. Most of those valves are AC 24 or 120 Volts AC

[ascientist]

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.

[Technician1002]

I've never tried to use a throw line. I'll look into it. Mason line comes in two varieties, twisted and braided. Get the braided as the twisted is more prone to twists and tangles.

Mason line is elastic enough to not snap when the line finishes paying out. With a loose arresting anchor, the snap back is eliminated. This is very useful for higher angle launches over trees.

For water bottle selection, the smaller water bottles are relatively uniform in diameter for vending machines but vary widely in styling. The thin filtered bottles and the thicker bottles for the sparkling water both work very well. Due to the uniformity of OD of the bottles, you do want the thin wall barrel. The bottles do not fit the Sched 40 pipe.

They fit the standard tennis ball barrel so if your landing zone has lots of people and the distance is shorter, you can switch between heavier bottles and lighter tennis balls.

[ascientist]

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.