Picture of Grappling Hook Launcher

As surprising as it is, there really is no where on the internet where I found any decent instructions on how to make a grappling hook gun. Figuring it would not be that hard to make, I decided to design and make one myself.  After running into  many problems, obstacles, and a few prototypes, I think I finally have a really solid version that definitely will impress all who use/see/build it.  Naturally there are sure to be plenty of upgrades and other ways to accomplish what I did but I will share the parts and methods I used to make this particular launcher.    
  Although I call it a grappling hook launcher, it is basically a souped up version of any pneumatic gun.  I took the best aspects of many different spud guns to make one of the best possible systems doing my best to avert creating any weak spots and not using any dangerous PVC (which shatters when over pressured and does not work well in the cold).  This system is designed to be robust and efficient in every aspect of its construction.  It is not hard to build and the most trouble anyone would have is gathering all the materials needed.
       I tried my best to used parts locally avaliable (Home Depot, Lowes, etc) but a few i needed to order online. Feel free to ask me any questions you may have. 
     For everyones information, if you are really that concerned about why I didn't film myself climbing the rope,  you are missing the purpose of the video, to show you how it works.  The hook and rope combined for my gun weight 2lbs 2.1oz for anyone concerned that this device isnt practical.  Also, I launched the hook at 150 psi and you could go much higher to achieve greater heights.  
     A little background on myself; I am current a Mechanical Engineering Student at the Massachusetts Institute of Technology  (MIT) and have been building things for 14 years.  My personal blog has most of my creations (some of them made by following Instructables).  Enjoy.  

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DJchmiel3 months ago
What is the purpose of the dry Chem tank?
JobertoL8 months ago

I'm just curious as to why you need the fire extinguisher tank when you already have the CO2 tank. Thanks!

teknohawk8 months ago

It looks awesome! Are you actually able to climb with the grappling hook and cable once it catches onto something?

gemoney1 year ago
can I use a different nerf rifle as the body for the gun and can I use a coaxial piston version to fire airsoft bbs from an airsoft barrel inside the copper pipe
-CCCP-1 year ago

This is just a QEV air gun.

stormneel2 years ago
wait what about the motor to ascending you faster so you don't have to climb
crreed (author)  stormneel2 years ago
I mean sure, you could use one, I personally have not designed one.
jorth crreed1 year ago

Strip down a winch for a truck or ATV combine with a few pulleys and a harness. ta-da then combine them

hbutler11 year ago
Do you need a check valve

Not at all.

have u tried to use a big co2 tank the ones they use for paint balling

DanTDM1 year ago

I am The Diamond Minecart.

gorillazo1 year ago
If I were to follow your plans as closely as part availability would allow but used a larger barrel for tennis balls or t-shirts, do you think I'd have issue with distance or power?
Can u build me one?
OS_Epsilon2 years ago
Are you willing to make one for me?
Chillawolff2 years ago
I tried to build this myself, but it won't work. I was wondering if you could build it for me. I know this defeats the purpose of this website, but I was wondering if you could do it for me.
crreed (author)  Chillawolff2 years ago
Send me a picture of what you built and I will try to help you out
de05093 years ago
I get that the sound is one aspect to be taken into account for grappling hook guns. it is mostly used to sneak, but I would really like to ask if it would be good to use water bottle rockets to carry both the hook and the rope? water bottle rockets have large momentum and should be able to carry a sturdy hook and stronger rope to huge distances, provided the rope supplied is long as well.
crreed (author)  de05093 years ago
Water bottle rockets would never have enough force to carry much of anything besides itself
de0509 crreed3 years ago
Sir, Id rather have half my monthly allowances in exchange for your badass gun but I beg to differ. law of conservation of momentum will cause the bottle to have equal (sum of) momentum with the water thrown backwards. And we know that water is heavy and they splash very hard backwards, thus momentum forward is powerful as well. Also, people had been shooting water balloons(water is heavy) using a water bottle rocket. I may be too young to create such a gun, but Im at the gathering-ideas phase.

crreed (author)  de05093 years ago
the water is minimal you put in the rocket. A gallon of wate ris about 8.33 lbs and the amount in a rocket is no where near that, more like a few ounces (as the bottles they launch are usually about 20oz and we can essentially consider the plastic massless). Although they have a high velocity, the water weight is minimal so the momentum is relatively low. However, the momentum is not particularly relevant, more of the force that is required to launch the projectile (the grappling hook). I havent done the math but the force is fairly high in order to launch a 3.5lbs object over 80 feet at a 70 degree (or greater angle). So you could probably calculate this all out and see, compared to a bottle rocket which is esentially massless once in flight, that the two forces are greatly different.
water bottle rockets are extremely louder than this...then you would be soaked with water...
iBite-kun4 years ago
I don't understand the purpose of having both a fire extinguisher and a CO2 tank. Why?
The fire extinguisher on it's own has no pressurized CO2 inside since you emptied it. Therefore you need to add some to it, hence the CO2 canister.
or you could fill it with compressed air or propane
does the fire extinguisher act as a secondary?
crreed (author)  iBite-kun3 years ago
The CO2 in the canister is at a very high pressure (greater than 1000psi). This is too much for the launcher so only about 200psi is put into the fire extinguisher at a time which then, in turn, is used to launch the grappling hook.
Ruminator3 years ago
Outstanding Ccreed, any idea what the muzzle energy is at 150psi?
xprosario3 years ago
Osama is alive, paparulo.
ro'keefe4 years ago
out of curiousity, what is the approx cost of this? im a college student (NCSU engineering!!) and dont have a ton of extra money, but this is just awesome and i really want to make one
crreed (author)  ro'keefe4 years ago
really depends on how thrifty you are and if you can find old parts. to build it completely new would be about $125-$175

twhitfield4 years ago
Anyone know if commercially available guns are unreasonably expensive? I'm thinking that this would make a good addition to a rescue team/firefighter tool set...not so much for climbing but with a "soft" grappling hook this could be used to get ropes to people stranded in flood water, etc. Just a thought for real world application....
A few kayakers I know, including myself, use the tennis ball throwers from pet stores for this. Accuracy is high, max distance is pretty consistent (and far), and the portability/reliability is unbeatable.

Just punch a hole through a tennis ball, put your line all the way through the ball, tie a stopper knot (http://en.wikipedia.org/wiki/Ashley_stopper_knot) on the tail of the line and start practicing.

Remember to never stand in the bight (don't position yourself where you could get tangled in the line). Also, only use line appropriate for your purpose. If you want to throw a safety line, make sure the line is a safe one (weight-tested, in good condition, etc.), you are just throwing a service line so that the distant party can then pull the heavier rescue line across, make that clear to them before throwing, and make sure they understand.
tinker2344 years ago
wow hey ideas on how to make a small pistol verison small motor like mythbusters did
crreed (author)  tinker2344 years ago
Ive never seen it but it seems like it would be near impossible at this point to make one the size of a pistol unless you could find some very strong spring or other compressible device to create a spring force of some sort.
gnarf_ crreed4 years ago
pistol crossbow?
mythbusters super hero epide also just so you know it might be posable to make it smaller
PSI, volume, flow rate, and dumping rate all vs. weight of hook/projectile.

Maybe a couple CO2 carts and a good dump valve (thought the pierce hole of a CO2 cart might be the limiting factor.)
jthomas424 years ago
If you go to www.brooksequipment.com or any local fire extinguisher service place, they have whats called a hydro test adapter that has the proper threads to screw into the unit. On the adapter is a 1/4 F Npt thread to attach an air chuck used when testing these portable units. all you will need is the model of the unit of the fire extinguisher you are using and that is found on the sticker. most units have a 585 psi range they are tested and rated to.
tinmanm4 years ago
I see you are using tissue paper as a packing for the grappling hook. Try a small amount of water 1/4 cup just ennogh to fill the valve. This works great for my air cannon that shoots ping pong balls.
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