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Hydro/pneumatic gun

Discussion in 'Pneumatic Spearguns' started by omega3, Mar 15, 2008.

  1. omega3

    omega3 Guest

    Well my father finally brought my 2 Ukraine guns to me . I bought them in 1994 brand new for approx £5 each and I think they are very cool . The lower gun is a bit of a rareity I think.

    when the spear is inserted, the water in the barrel is squeezed into the rubber sleeve through about 20 small holes.

    when fired the spear is squeezed or spat out for want of a better term by the compressed air squeezing the sleeve. It works very well. What I find very cool is it is effortless to load and I mean effortless. It would be like loading a gun with half a bar pressure in it. It has a fair bit of power and next to no recoil as well as being near silent. It also can`t fire out of water unless the tube is filled with liquid(long story there)

    So a bit of an anomaly I think when compared to say the Mamba system. It has the seals to keep the water out and this has the same seals to keep the water in.

    I was servicing them to replace the awful quality seals which were in good condition but so poorly made. The rest is as good a build as any

    I like it!
     
    Last edited by a moderator: Jun 16, 2010
    Pastor likes this.
  2. Pastor

    Pastor Supporter Supporter

    Local Time:
    4:42 PM
    There is some radical and excellent guns made out in the old USSR, Hyeparis is the guy in the know and with some seriously funny stories to go with them, usually involving his drunken mate falling around on the riverbank :)
     
  3. azapa

    azapa 51% freediver 49% spearo

    Local Time:
    12:42 PM
    they look awesome in that green adonized finish! whats the second trigger for on one gun?
     
  4. omega3

    omega3 Guest

    Thats the safety. Just push finger forward to release the safety. It comes on automatically when the gun is loaded as the spear locks home. Another good idea. The rear sight is also pretty cool , it stores line and releases forward when the trigger is pulled and locks when the gun is loaded.......clever or what??

    Nice tip Pastor I look him up.
     
    Last edited by a moderator: Mar 16, 2008
  5. popgun pete

    popgun pete Well-Known Member

    Local Time:
    1:42 AM
    I found this thread on a search, hence a bit late in commenting. I have two of the RPS-3 spearguns (PПC-3 in Russian) which use the rubber sleeve on multi-ported barrel system to separate injected water, during muzzle loading, from the compressed air reservoir. One is brand new, never been in the water, but the other is in very poor shape. I was wondering how your gun has survived use in salt water. Many of the smaller mechanism parts are only plated steel (looks like cadmium plate on the unused one, some silvery-grey stuff on the other, older, example) which seems to have suffered badly from immersion in seawater. In fact the gun is essentially ruined, so I completely disassembled it including the rear mechanism parts that are never meant to be removed, having been staked in place. Back home in the Ukraine and Russia diving is conducted in freshwater lakes and rivers, thus internal speargun corrosion is not such a worry in the short term. The design of the RPS-3 trigger mechanism is unique in that the size limitations imposed by mechanically releasing a spear tail which has to pass through an all important muzzle seal left little material to work with. For example the sear "tooth" (actually a tiny angled step inside a metal disc) moves only 1.5 mm to release, that being all that the sear tooth hangs onto on the mushroom headed shaft tail. It is so marginal that I wonder that anyone contemplated making a speargun this way, because that release system required very tight machining tolerances to make it work. The designers seem to have been driven by the desire to make something that was completely different from how other guns worked and they certainly achieved that, but at what manufacturing cost? I could never see a speargun like this being made in the West as you would go broke making it with all the precision machined parts, yet the rubber seals must be the worst that I have ever seen in a speargun, being rubber packing's rather than "O" rings, and very poor ones at that.
     
  6. popgun pete

    popgun pete Well-Known Member

    Local Time:
    1:42 AM
    Here are some photos showing what lies inside the rear housing of the Ukrainian RPS-3 hydropneumatic speargun. This particular gun has a crack in the rear housing due to it being forced together with additional rubber packing in an attempt by a previous owner to improve the sealing action on the mid-section; it didn't!

    I only bought this gun to dismantle it, so took to it with hammer and hardened steel punch to drive the staked in place mechanism pivot pins (2 mm dia.) out. They are not intended to be removed, so the inner mechanism parts are rarely seen by anyone outside the Ukrainian factory. The small steel parts shown here are very susceptible to rusting as the rear section completely floods, so they are exposed to saltwater during any ocean usage (galvanic corrosion will then occur between the different metals used which will progressively destroy any protective plating). The components used are not stainless steel unfortunately, which means that if the gun is not washed out with freshwater after a dive it will not last long once the various small springs start to disintegrate and the sliding steel parts pit with rust.
     

    Attached Files:

    Don Paul likes this.
  7. omega3

    omega3 Guest

    Hello Popgun Pete
    Mine are Ok but they but are used so rarely and washed. There has been rusting on the "sear" tooth bits you mention though they have cleaned up OK as well in the past. All my trigger bits have been fine but they are well smeared in silicon. The problem with the RPS 4 at the moment which I cant see solving too soon is the handle moulding onto the alu. is slipping so I can`t tighten the back up to seal. What a pain!
    You mention manufacturing cost and production in the West going broke etc. This is/was Former USSR we are talking about here with all its pros and cons and it cost about £5 new. I am sure the maker is not living the high life and is probably broke too! Heck, when I was there in 94/95 I had to exist on stuff like (as in slightly similar to) bread and cheese and was Mickey Finned the first day I was able to buy beef and potatoes, more long stories there!

    Its good to see another one about. How successful have you been with your RPS 3 ?
     
  8. popgun pete

    popgun pete Well-Known Member

    Local Time:
    1:42 AM
    I have not used either of the RPS-3 spearguns, I really bought the first one to check out the engineering of what seemed to be an improbable design for a factory production speargun. They were manufactured for about twenty years and the official price of 55 roubles was incorporated into the moulded lettering on the LHS of the rear plastic grip, so the sales price was essentially fixed. That price also featured prominently on the brown vinyl carry bag which transported the hand pump as well for travel purposes. On the much later guns that lettering on the handles looks to have disappeared in the web forum photos that I have seen. Some RPS-3 guns had white handles instead of black and there appears to be a beige version as well. The plastic handles are not particularly durable, they can develop cracks, which may be due to the type of plastic used, plus it is a bit thin in section in some places which does not help the situation.

    I bought the second RPS-3 gun in order get at the sear disc as it would have needed a hacksaw to open up the mid section on the used gun which has been glued up, probably with a silastic type of material on the screw thread to prevent leaks. It would not budge even when locked up in my lathe and with a metre long bar applying torque to a snug fitting rod passed through a handy inspection hole after the innards of the rear housing were removed. Once I saw what the unused gun was made of inside (everything unscrewed relatively easily) I realized that our salty conditions would not be kind to it. I already owned a couple of Aquatech hydropneumatic spearguns which use a better operating system and are made of more corrosion resistant materials, so the RPS-3 was basically acquired for its curiosity value.

    The RPS-3 speargun throws a 9 mm diameter shaft, which is asking a bit much from a small gun that has to pass pressurized water through a sieve (the multitude of holes peppering the inner barrel wall) and still expect some performance out of it. First time I saw the drawings of the prototype gun I thought that it was someone's wishful thinking on how to make a gun that totally defied accepted practice, so I was amazed that they had been made, and even more amazed when I discovered that they were mass produced. That is why I had to have one, but the production gun introduced some unfortunate changes and only appeared as a short, low visibility model rather than the 950 mm length of the prototype. Given the inefficiency of the "hose type" hydropneumatic guns that may have been a good decision, but switching from "O" rings to rubber packing items for the seals made the gun a potential leaker of both air and water under high pressure. It is not just a substitution thing, they also changed the metal parts where the inner barrel seals inside the gun. That gives rise to slow leaks which depressurize the gun over time, which is not so good as for transport the spear is stored inside the gun! Without water inside the gun that should be OK, but escaping air slowly pressurizes the inner barrel and the unwary have had the spear fly out when they pulled the trigger on a supposedly non-charged gun after they had removed it from the carry bag and went to pull the spear out.
     
    Last edited: Jun 4, 2010
  9. omega3

    omega3 Guest

    Interesting.

    Yes the plastics on the 4 are awful.
    On a slight change of subject but related, I have a few Mambas and don`t think too much of the trigger pins assembly or build quality either and have had leaks etc. which was solved by new larger pins/seals, I read from Spaghetti they have now gone bust too. Who are these Aquatech?

    Thanks
     
    Last edited by a moderator: Jun 4, 2010
  10. popgun pete

    popgun pete Well-Known Member

    Local Time:
    1:42 AM
    The Aquatech is another hydropneumatic speargun from the Ukraine, but it is not mass produced and is only made to individual order. The English version of the Aquatech web-site has recently been updated to show their newer models which use more plastic parts than their earlier guns. http://www.aquatech1.narod.ru/index1.html

    Basically the Aquatech guns use a hydraulic valve based trigger system to control the release of pressurized water rather than a mechanical catch operated via a sliding linkage arrangement to release the spear tail, so there is no sear tooth to wear out. The moving pressure bulkhead is an annular piston sliding in the concentric space between the inner barrel tube and the outer body or air tank, unlike the expanding and then collapsing rubber hose system used in the RPS-3 to separate air and water under pressure. Being valve based you can pump extra water into the Aquatech gun using the spear, something that you cannot do with the RPS-3. That allows you to increase the pressure that will be available for the next shot.
     
    Last edited: Dec 1, 2010
  11. omega3

    omega3 Guest

    Thanks Pete

    They look very interesting. I see an RPS-3 on the site. Very cool!

    I just sent him an email.
     
  12. popgun pete

    popgun pete Well-Known Member

    Local Time:
    1:42 AM
    Anyone who is curious about the RPS-3 speargun's internal parts can see one being methodically dismantled on http://apox.ru/forum/index.php?showtopic=7362. If the link does not work from this web-page then copy it and paste it into the address bar at the top of your browser. On-line translators will convert all the posted Russian text into English if you click the "translate" tab, but not the captions on the diagrams, however they are reasonably self-explanatory.

    I was not so organized as to take photos during my own dismantling effort, but proceeded in a similar manner. The trigger mechanism did work again on gun reassembly, however the crack in the rear housing was machined away and this gap (see photo) has to be rectified with an insert and extra seals for the gun to ever hold hydrostatic pressure again. For comparison it is shown alongside a rare unused example of the RPS-3 speargun (1990 production). The RPS-3 guns are intended to separate for maintenance where the groove has been cut, but as this section floods with water the large connecting threads there can eventually seize from corrosion if the gun stays closed up for very long periods. If this seizing occurs then the guns tend to only unscrew at the rear of the air pressure reservoir (once the reservoir is depressurized), which is what you see here as this section remains dry and the screw threads therefore stay in much better shape. Or I should say it is intended to be a dry area, but I have found that some water does enter in very small amounts via the packing seals at each end of the inner barrel as they also slowly leak pressurized air from an unloaded gun (this may be a design problem!). When the gun is cocked and ready to shoot these packing seals (two square section rubber rings grouped together at either end) face the same pressure level on both sides; air on the compressed air reservoir side and water on the other side which is at elevated hydrostatic pressure throughout the cocked gun. During insertion of the spear shaft into the gun the trapped water in the inner barrel not only expands the rubber pipe radially outwards against the surrounding air pressure and away from the exterior of the multi-ported inner barrel tube, this progressive displacement of water by the body of the spear shaft entering the gun also pushes some water through any tiny leak path in the rubber packing rings! If this water is saltwater and progressively accumulates inside the air pressure reservoir over time then corrosion will start to gnaw away at the aluminum parts, the steel washers behind the rubber sealing rings and the thinly plated steel air pressure release screw much faster than if it was fresh water. Owners who remain oblivious to this occurring then find subsequent dismantling of the gun becomes impossible without damaging the surface finish of the gun and possibly irretrievably damaging major parts which cannot be readily replaced.
     

    Attached Files:

  13. loka

    loka Active Member

    Local Time:
    4:42 PM
  14. popgun pete

    popgun pete Well-Known Member

    Local Time:
    1:42 AM
    Thanks loka for directing us to this very interesting series of photos of the rare "Wasp" speargun. Previously I have only seen the "Wasp" rear handle photo sent to me by Hanter. So this is what the "RPS-3" speargun could have been, a gun which with a change of forward barrel and spear shaft transforms into either a long gun for open water shooting or a small gun for limited visibility hunting. This would be reasonably quick to do as the barrels can be swapped while still pressurized with air. The "RPS-3" (PПC-3 in Russian) from Uman plant "Vega" has had several changes made to the lower stirrup section of the hand pump judging by illustrations in various editions of the handbook supplied with each gun. For those unfamiliar with the "RPS-3" the hand pump straps over the barrel just in front of the handgrip where the inlet valve is located. The clamped assembly of gun and hand pump forms a "T" shape, you place the folded-out tubular handle of the pump on the ground and grasp the gun body with both hands on either side of the stirrup fitting, then with your feet placed on the tubular handle you pump the gun up and down using the actual body of the gun as a giant pump handle rigidly connected to the body of the pump while the pump rod remains stationary. This sounds like a strange arrangement, but is actually a very easy way to pump the "RPS-3 gun up to operating pressure. You need it because the "RPS-3" hand pump rubber seals are a tight fit in the bore of the pump and make you feel like you are pumping glue!

    The text accompanying the "Wasp" photos indicates that the speargun dates from 1973. The handbook for the "RPS-3" states that the gun is built to specification TU 3-1021-77, does the "77" suffix mean that the "RPS-3" speargun production will have commenced in late 1977, or perhaps 1978? An article by Nikolai (Kungur) and Yevgeny (Samara) speaks of a 5 year testing of the prototypes, so if the "Wasp" is the prototype then this seems to indicate a 1978 start date for mass production of the "RPS-3". Is this correct?

    Judging by the apox.ru web-site photos the "Wasp" has highly desirable stainless steel trigger parts and the allegedly fracture and wedging resistant line slide described in the above article. Also the plastic rear grip handle has a higher position on the gun in terms of the centre of grip pressure, something which could have been done with the "RPS-3" if the plastic moulding had been altered, but perhaps the rear shape of the production gun's grip is more comfortable when loading the gun on the upper leg.

    The "Wasp" and "RPS-3" spearguns show that with enough design and engineering effort even the most unlikely concepts can be made to work, but at what production cost and what limitations on performance as the efficiency of the rubber hose (pipe/sleeve) design is problematic. Don't get me wrong, I think the gun is a tribute to the people responsible both for its creation and production, but surely their effort would have been better expended on something more conventional. Then maybe it could have been produced using better materials rather than spending most of the production budget on the large machining costs required for parts like the rear housing which has been milled from numerous angles to produce a highly complex shape. It is not the sort of thing produced on anything other than a numerical controlled, multi-axis milling machine and bear in mind that each one had to be made from round aluminium alloy bar stock for every gun! Yet the "RPS-3" was sold for only 55 rubles, which does not sound like a large amount, although it depends on what people earned back then as a weekly wage or salary.
     

    Attached Files:

  15. loka

    loka Active Member

    Local Time:
    4:42 PM
    This speargun schematic was published in 1978 in "Спортсмен-Подводник" (USSR diving and spearfishing magazine).
     
    Last edited: Dec 2, 2010
  16. popgun pete

    popgun pete Well-Known Member

    Local Time:
    1:42 AM
    Then 1978 must mark the release of the mass production version which is the more familiar RPS-3 with the green anodized body. I have had a closer look at the schematic for the prototype and it is virtually the same as the production RPS-3 except that the grip handle has a more rounded butt compared with the squared butt of the production gun. The production butt added a short skirt which when viewed from side on hides the butt swivel ring inside the profile of the lower handle. The "Sea Wasp" now appears to be a much later interpretation of the design which has reverted to the original line slide in place of the plastic item with four "stabilizer" fins, plus the "Sea Wasp" was supplied as a long and short barrel version thus realizing the original concept for the gun.
     
    Last edited: Dec 7, 2010
  17. popgun pete

    popgun pete Well-Known Member

    Local Time:
    1:42 AM
    Here is the diagram from the publication "Sportsman-Submarine", issue 51, 1978. The "RPS-3" as originally conceived.
     

    Attached Files:

    Last edited: Mar 15, 2012
  18. loka

    loka Active Member

    Local Time:
    4:42 PM
    РПС 3 can be easily converted to a pneumovacuum speargun by replacement of the internal drilled barrel on not drilled. And piston must be added too.
     
  19. popgun pete

    popgun pete Well-Known Member

    Local Time:
    1:42 AM
    I can imagine a new piston with a rear end like the existing spear tail to fit the unique vertical motion sear release disc, but how would the air flow from the concentric tube outer reservoir enter the inner barrel to drive the new piston? The existing barrel completely isolates the air reservoir from end to end, the transmission path for the working fluid is the many small holes that ventilate the rear half of the inner barrel. So there would need to be "windows" in the rear end of the inner barrel as the "working fluid" will now be air, maybe not such a problem as the outer body tube is the structural element holding the speargun together, not the inner barrel tube. There is also the matter of a shock absorber on the piston, or the muzzle, plus a muzzle diameter restriction would be needed to retain the piston in the gun. Most attractive aspect is the elaborately machined sear disc and internal parts could then be oil lubricated, as they are now they are exposed to water and hence corrosion. How have such converted guns performed compared to the original design, both in shooting performance and operating noise? I would expect that the working course of the spear would be reduced as there is the length of the new piston to take into account and the location of the muzzle restriction which retains the piston.
     
  20. loka

    loka Active Member

    Local Time:
    4:42 PM