your thoughts on Air tank opperated gun

[jzuk]

Hello all,
I'm trying to get a feel for this idea from spearfishing dudes and dudets.
My thoughts are to make a pnumatic gun that will be pumped through an air tank.
For scuba divers, it will probably be very easy to do, however, most hunt while freediving. Hance I'm planning to use a small and light tank. Volume will be determined later with respect to the amount of air needed for every shot. It will be small. could be attached to the rifle or diver.
I've just started to roll this tought in my head as part of a project I need to do for uni.

Please feel free to comment.

thanks,
Johnny

 

[trux]

Hello Jzuk. You may want to check your local spearfishing rules and laws before working on it. In many Mediterranean countries, pneumatic guns may be loaded only manually - no powering with air from compressor or from external tanks is allowed. I do not know though what the laws tell about it in Israel.

 

[Mr. X]

Re: your thoughts on Air tank operated gun

There was a thread discussing historic spearguns a while back. Somebody added a reference to a US website which cataloged a large number of unusual & unique designs (I believe they were about to re-implement the website at the time of the discussion). They had several, thin, light pipe guns which I think may have been tank filled spearguns - but not certain. They looked like they might be very good, powerful & agile but perhaps a bit utilitarian looking (like something left over in a plumbers bag). I do recall one clever design that use an old fire-extinguisher as a resevoir (I kid you not). Some of the designs are fabulous, with drag parachutes & all kinds of dodas. Some/many were used to spear huge fish.

 

[Old Man Dave]

Guns that use any expelled gas (as oposed to sealed pneumatic systems) are banned from competitions and claiming records. Also illegal in some countries. However, it was good enough for James Bond (original Thunderball), where he had a couple of rocket launcher style either side of his tank plus the "normal" sealed pneumo (actually a Technisub Jaguar) in his hand.

Would be easy to build one and yes I've seen the pictures of fire extinguisher models (they have the tank and the trigger already built for you). Spears could also be hollow creating fuel for in flight making a rocket spear gun. Co2 guns and blank cartridge firing guns were commercially made in the past in the USA (by a company called SMG - I think).

Good luck to you but just makesure you don't kill yourself (or someone else).

Dave

 

[wet]

Just wondering, could a little CO2 cartridge provide enough power to launch a ultra-thin spear to kill a fish (not a huge fish) in reasonable distance?

I saw Bill's CO2 inflatable float used while spearing fish in kelp, was thinking that the same CO2 that powered the spear could be expelled into a float upon squeezing the trigger, as a single operation. But maybe the CO2 doesn't have enough oomph?

http://forums.deeperblue.com/hunting-equipment/80189-pinch-weights.html#post735248

probably a dumb question, but a cool concept!

 

[jzuk]

Thanks for the replys guys. Didn't think of the law issue but i'll check it.
I'll run a search for that old thread and try to enrich my knowledge.
I don't want to invent something to make money from, just thought it be a good idea for an engineering project.
Cheers

 

[Cammo]

Hey J,
You need to get a hold of the movie - "Caza Submarina extrema en Gabon" con Marc-Antoine Berry. The language is in Spanish, but its a good watch. It shows his gas bottle, how he fills it up from a dive tank, screws it on his gun, and shoots 100kg plus grouper with it (can't say I really recommend that too often). There is a bit of footage on his gun and really worthwhile for your project.
The pressure in a dive tank is usually 230 bar I think? Most guys run their pneumatics around 25 bar, but most guns handle 30 bar, just very hard to load by then! So 230 bar has a lot more potential power stored up!
Also look at the thread on the Russian? guns that run up to around 1000 psi - 65 bar, they use the same principle as a hydraulic jack and you pump sea water into the chamber every time to load it.
Popgun Pete is one of the experts in this area.
I would think the smaller the cartridge you go for (like those whipped cream CO2 bottles!) you may only get one shot out of it? Might not be very wise for a long term gun, as you would have to carry around a heap of mini bottles, fine for a project though and guess you won't run out of whipped cream eitherrofl
Just to possibly add something new to your design - you could add in the mamba kit/tovarich system, so there is no water in the barrel next to the spear when you fire, futher increasing the power (and making it more efficient at lower pressures/volumes like the CO2 cartridge).

 

[popgun pete]

"Ferro Firearms" offered a speargun that was powered by a low pressure feed from a scuba tank regulator back in the eighties. It seemed to sink without trace!

 

[fer_abella]

MACO² Spearguns

buy one

 

[foxfish]

Hmm very interesting although I couldn't find any performance figures, the guns do look well made not cheap though!

 

[fer_abella]

See video "extreme spearfishing" in Gabón - Michael Reboul - to see performance.

 

[foxfish]

I will have to try & find that - but can you say if it works well?

 

[Fondueset]

Co2 guns have been around for a long time. They are very powerful - similar to the SMG guns - which used various gradations of .22 blank cartridges.

Expressing my purely personal view on the subject. I do not think apnea spearfishing is about using the most efficient technology to kill fish. The difficulties we encounter in the process of stalking fish in their own environment, with only the air in our lungs, does not, to my mind, seem to be about making things easy. On the site for these guns the designer mentions he thinks the laws requiring that a spearguns power be related to the loading effort are outdated. I submit to you the orientation such laws express is essential to the integrity of the sport - to its very essence as an activity that is about skill and harmony with the environment. I don't think any of us do it because its easy. Otherwise we'd all be hunting down the Russian assault rifle that shoots a super-cavitating round out to around 30m.

 

[foxfish]

Absolutely - but it don't stop me beginning interested in all types of speargun.
From my experience of Co2 powered riffles they are dependent, to a certain extent, on the ambient temperature which can effect the performance quite considerablly.
on that basis Co2 spearguns might not work very well in cold conditions?

 

[popgun pete]

Carbon dioxide powered spearguns had their heyday in the fifties and sixties. The Maco gun is a modern take on the French Pelletier guns from that era. The operating temperature does not affect them too much as water temperature does not vary a lot in any particular location. Plus shooting distances are shorter underwater, so less variability than in air with pellet guns. Carbon dioxide is stored as a liquid and converts to gas offering around 900 psi propulsion pressure. You have that pressure until the last drop of carbon dioxide liquid transforms into gas.

The guns fell out of favour once rules were implemented to ban them from spearfishing competitions.

 

[Cammo]

Wowee, those MACO2 spearguns aren't cheap, around 700 Euros up for the small one!
Would love to just fire one however, to see what it was like:martial
Do you have to recharge every shot? Seems like you have to charge the handle every time? Would be a pain if you did.
If you go to "BONUS" then "links" it shows a history of CO2 spearguns, very cool
Just got my tovarich system from Ramon, soon to be fitted to my Cyrano 1100:t

 

[fer_abella]

Mako2 is an extremely powerful speargun.

Compare it to a 6 bands 170cm long 9mm shaft gun.

You obtain quite a number of shots with no efford from the ponny bottle. You just put the shaft in place and pull the trigger.

No problem with temperature. Of course any gas loaded at 300 bar at 30 celsius degree convert to another preassure at 10 º celsius, just phisics.

 

[spaghetti]

Fernando, what are the downsides of this gun? (weight/manouverability, maintenance, shaft velocity...there must be something uncomfortable with it....or is pure perfection?)

Re Fondueset: if you ever change your mind....Modern Firearms - APS underwater assault rifle

 

[fer_abella]

it does not float and it is heavy.
it does not operate without access to high pressure air.
it has a limited number of shoots before recharge
it is not cheap
it is illegal in some countries
it needs shafts made to it
it only works with very straight shafts (not bend ones)
it is not as reliable as bands spearguns if not well mantained

vs

it is rugged
it is small
it is powerful
it does not need any power from spearo
it is acurate