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A042 - Titanium Spearfishing Spear Gun Lantan Underwater Dive Speargun

popgun pete

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Jul 30, 2008
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The safety lever assembly in the low power shot position. Note the flats on the shaft that have now slid into view after emerging from the left hand side of the grip handle.
ready for low power shot.jpg
 
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popgun pete

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The above hydropneumatic gun is by Valentin. Below is a pneumatic version using the same stylistic principles. Not a mass production gun, unlike the Girstitan being discussed here. The pull rod running under the tank indicates a forward latching weapon. The garpun website had some info about him, but the site seems to have disappeared!
russian pneumatic.jpg
 
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popgun pete

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The use of plastic to mount the trigger mechanism has reduced the potential for galvanic corrosion as the stainless steel releasing valve body does not actually touch the titanium of the receiver and its tail end only contacts the electrically isolated parts suspended in the rear grip.
Threaded socket in front of grip.jpg
 
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popgun pete

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An inner barrel diameter of 11 mm is relatively large for a hydropneumatic speargun, although in the early days of hydropneumatic guns such as the Alcedo "Hydra" inner barrel sizes were the then "standard" 13 mm diameter. They were also the days of 9 mm diameter spears and even larger for shooting enormous fish cowering in caves! Once shooting bans came into effect to save the dwindling stocks of these big fish in the more accessible locations that was the end for many of those big guns and spearfishermen also regained their senses. Eating a fish the size of a small car was not very appetizing!

Hydropneumatic guns have been described as temperamental and capricious when they can quit working for no apparent reason, but this is usually a result of poor maintenance. That includes after post-dive cleaning and rinsing if they are to be stored for a lengthy period then you dry them right out which usually means some disassembly. With this Girstitan gun being made of titanium it should be relatively impervious to marine use, but my advice is to always take such guns apart by at least pulling the releasing valve out. If nothing else it renders your gun useless if anyone decides to steal it as then they will not easily be able to replace that part which you keep separate from the rest of the gun.

With Aquatech guns no longer being made I think that this would be the only off-the-shelf hydropneumatic speargun available today if you exclude the forward latching guns such as the “Kobra”.
 
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popgun pete

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This diagram shows how water injected during muzzle loading squeezes past the rubber cuff on the releasing valve by pushing it back on its biasing spring while the releasing valve body remains locked in place by the trigger mechanism.
Releasing valve action 2.jpg
 
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tromic

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Aug 13, 2007
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This diagram shows how water injected during muzzle loading squeezes past the rubber cuff on the releasing valve by pushing it back on its biasing spring while the releasing valve body remains locked in place by the trigger mechanism.
View attachment 57497
Pete, how is the sliding rubber cuff sealed to the releasing valve body? Has the biasing spring some role in that?
 

popgun pete

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Jul 30, 2008
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Pete, how is the sliding rubber cuff sealed to the releasing valve body? Has the biasing spring some role in that?
The hydrostatic pressure when the gun is charged forces the rubber cuff against the metal disc and its connecting cylindrical shank that forms the front of the releasing valve body. You could compare the rubber cuff to the sealing flange of a plug in a sink outlet, but here it seals a thin ring around the metal head of the plug and the rear face of the inner barrel. Because the annular gap created is small the hydrostatic pressure cannot force the rim of the rubber cuff through the gap. That gap has ambient pressure in the inner barrel on one side and charged to shoot pressure on the other side created by the annular piston transferring air pressure from the tank to the water trapped in the rear of the gun. The biasing spring helps to return the rubber cuff, but the hydrostatic pressure is what really seals it as any water flow is cut off before it can escape through that small gap.

Note for these releasing valves to work the diameter of the rear bore that the releasing valve's body "O" ring is located in is always larger than the bore of the inner barrel.
 
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tromic

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Aug 13, 2007
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The hydrostatic pressure when the gun is charged forces the rubber cuff against the metal disc and its connecting cylindrical shank that forms the front of the releasing valve body. You could compare the rubber cuff to the sealing flange of a plug in a sink outlet, but here it seals a thin ring around the metal head of the plug and the rear face of the inner barrel. Because the annular gap created is small the hydrostatic pressure cannot force the rim of the rubber cuff through the gap. That gap has ambient pressure in the inner barrel on one side and charged to shoot pressure on the other side created by the annular piston transferring air pressure from the tank to the water trapped in the rear of the gun. The biasing spring helps to return the rubber cuff, but the hydrostatic pressure is what really seals it as any water flow is cut off before it can escape through that small gap.

Note for these releasing valves to work the diameter of the rear bore that the releasing valve's body "O" ring is located in is always larger than the bore of the inner barrel.
Yes, I thought it was like what you explained.
It is similar in working principle to one of my early ideas presented on this forum some years ago, but this is for hydro pneumatic supergun and has more simpler design and is actually proved in exploitation. My remained just as an idea..

1631631514618.png
 
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Zahar

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Jun 3, 2014
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Yes, I thought it was like what you explained.
It is similar in working principle to one of my early ideas presented on this forum some years ago, but this is for hydro pneumatic supergun and has more simpler design and is actually proved in exploitation. My remained just as an idea..

View attachment 57498
Контилинка - эскиз - копия.jpg
 
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