Aquatech "Dnepr" hydropneumatic speargun

[Jegwan]

Here's a small 35cm "Dnepr" speargun made by Aquatech, S.F. Kravchenco in Ukraine April 2010.

The "Dnepr" is a hydropneumatic speargun, which means that it's a pneumatic speargun with water acting as a transmission element between a piston fronting the air reservoir and the tail end of the spear (See the brass tail end with the O-ring below).

It's powerful compared to it's size and it shoots quite silent.

The "Dnepr" is made to order and can be supplied in various lengths (25cm to 150cm) and handle positions (A, B, C). It's possible to exchange the complete concentric barrel in different lengths on different handles.

The "Dnepr" has a hydraulic trigger mechanism. It works like a one-way valve during cocking so that the gun can be loaded in stages. This stage loading makes it possible to load or "pump" the spear in steps against a quite high internal air pressure.

Here's the inside og the "dnepr":

The outer barrel is a OD 30mm aluminium tube. The inner barrel is a ID 9mm SS tube. The concentric barrel is closed in each end with a threaded (27x1mm) plug (the front cone and the rear Barrel plug).

The annual piston seals towards the outer and inner barrel and moves forward when the gun is loaded.

The inner barrel is fixed and sealed by a simple O-Ring in the front cone. The pressure in the gun keeps the O-ring and inner barrel in place.

The line release hook/plate can be placed so the line release hook is on the side of the gun the user prefers .

Jégwan

 

[popgun pete]

Well it is interesting to finally see what is inside. The "wet parts" of those guns are easy to open up, but on my "Aquatech 500A" all the air pressure bulkheads would not budge despite using long arm pliers with layers of polyethylene straps (cut from a 3 litre disposable milk bottle) to protect the anodized and knurled surfaces from damage. Of course I had let all the compressed air out first. I asked Sergiy about it and he said maybe the "O" rings had swollen with oil absorption rendering everything tight. So I left it alone as only curiosity was inspiring the desire to dismantle it.

 

[popgun pete]

Before I purchased my "Aquatech 500 A" ("A" - rear handle), the forerunner to the "Dnepr" (named after the local river), the "Aquatech" web-site was only in Russian. I just found it by accident when I searched on "hydraulic speargun" merely out of curiosity to see if anything at all appeared (at least some of the web-site's tag or "key" words must have been in English). That is when I first saw an "Aquatech" gun and I then used my "English to Russian" dictionary to translate what looked to be the key sentences on the page. No on-line translation for Russian was available back then (circa 1999), they were only available for the "Romance (a linguistic term) Languages" such as French, Italian, German, etc. I sent my English translations to Sergiy Kravchenko and he used them to create an English version of the "Aquatech" web-page, his English was much better than my Russian! A lot of water has flowed under the bridge since then. I later wrote most of the technical pages for the "Black Sea" gun, seeing as I had suggested a surcompressor gun with a small bore pump to help load the gun with and Sergiy then created the lever-operated hydropump version working through the hydraulic locking chamber. The idea had been used before, but not with the double-ended valve arrangement using the same spring for the releasing (firing) valve and the non-return valve on the hydropump. The emphasis was on safety as there were some concerns about arming divers with 1,500 psi spearguns! Fortunately there had been a brief precedent when spearguns were powered with 2,500 psi using expellable air to blast the shafts from the guns, but such guns were banned here, the key words being "expellable air/gas" as firearms have the same technical/legal definition.

So the little "Aquatech/Dnepr" was the basis for a line of very powerful and silent guns, one "clink" (the rebound of the biasing spring heard only by the shooter) and they (the fish) were gone (as in dead)! The only drawback is the guns don't float, although a big effort was made to lighten the handle, hence the version of these guns sold today.

 

[Jegwan]

Yes, the Aquatech "Black Sea" guns with hydropump. I remember the old thread regarding the "Black Sea" guns. Here it is:

http://forums.deeperblue.com/threads/aquatech-black-sea-hydropneumatic-gun.79732/

Link to the Aquatech gun descriptions on their homepage (I don't think that it's up and running):
http://aquatech1.narod.ru/english.html

Here's a picture of the Aluminium version in 100cm of the "Black Sea". The SS bracket with D-ring for line attachment is my own addition. The gun has the same 30mm Aluminium concentric barrel as the "Dnepr" and it's an absolute sinker. The fatter "Titanic" model (36mm outer barrel in titanium) might float in the later version with "plastic" (fibre armed resin) handle.

Jégwan

 

[popgun pete]

"Cammo" in W.A. has a titanium "Black Sea" model, a 1250 x 9 mm inner barrel version from memory. I never heard much about it once he had it all assembled. Someone took a shot with it and missed, not surprising given he, i.e. some other guy, had not pulled the trigger on one before. I don't remember whether it floated or not, but maybe now we are talking about "Cammo" he may chime in.

Things in the Ukraine don't look too good right now, so the speargun business may be on hold for some time.

 

[popgun pete]

I note that you received a handpump with its own pump rod and handle. On my earlier "Aquatech" gun the pump rod was one of the spears in conjunction with the hand loader screwed on top. The tail piece of the spear unscrewed and the piston of the handpump took its place. It is not unusual to see this arrangement used in Russian spearguns, for example the iconic Soviet-era "RPS-3". Although also made in the Ukraine, the "RPS-3" is a "Russian" design which current events now explain as an ethnic divide between the two countries that I had not realized before, thinking them to be more alike than maybe they really were/are.

 

[Jegwan]

Yes. the pump came complete. The pump rod is made from an aluminium tube and the handle is made a little shorter than the hand loader.
I'm not sure I understand what the conflict really are about. I suppose that money and political power also are in play.
I pray for non-violence and hope that any limitation in freedom will be short and temporary.
Jégwan

 

[EFISIO PIRODDI]

Siete poi riusciti a contattare Siergij krawchenco ? Adesso si può acquistare il MAR NERO? Ciao Efisio

 

[Jegwan]

I'm not sure if he's still in business. The Russian website is no longer available.
Jégwan

 

[EFISIO PIRODDI]

Grazie Jegwan , ho provato a contattare Siergij per diverso tempo ma non ci sono riuscito , quindi a gennaio di quest'anno ho iniziato a costruirmi un idropneumatico in titanio , con una forma diversa dal Mar nero però con le stesse prestazioni , cercando di eliminare i pochissimi difetti ( galleggiabilità , linea di mira , pompetta di carico laterale , rinculo , unica velocità ) . Il prototipo è quasi alla fine della realizzazione , mi manca solo un piccolo dettaglio....prima del mese di Dicembre penso che sarà finito.....Ciao Efisio

 

[Jegwan]

You are welcome. I have tried to contact him myself without success.
It sounds like a very interesting project. It requires knowledge and care to make your own pneumatic speargun. Remember to incorporate the necessary safety aspects under test and in the final gun.
Forum member Tromic and Popgun Pete are experts in the field. Try to contact them with your questions. I am sure that they will be able to help you.
Good luck,


Prego. Ho anche provato a contattarlo senza successo.
Sembra un progetto molto interessante. Si richiede la conoscenza e la cura per rendere il vostro fucile pneumatico. Ricordarsi di incorporare gli aspetti di sicurezza necessarie in prova e le fucile finale.
Membro Forum Tromic e Popgun Pete sono esperti del settore. Prova a contattarli con le vostre domande. Sono sicuro che essi saranno in grado di aiutarvi.
Buona fortuna,

Jégwan

 

[EFISIO PIRODDI]

Ho letto diverse discussioni dove voi parlate delle prove che avete fatto e dei difetti e dei limiti che avete trovato in questo idropneumatico , e sto costruendo il mio hidro tenendo conto di quello che ho appreso da voi .Se troverò delle difficoltà non esiterò a contattarvi per chiedervi un consiglio.....Grazie in anticipo ....Efisio

 

[popgun pete]

Sergiy Kravchenko lives in the Ukraine, which is having "border problems" with Russia right now, hence the "Aquatech" speargun business may be out of action for some time until the political/industrial situation there changes for the better. I have had no contact with him for years, my last e-mails to him went unanswered. I need parts for one of my "Aquatech" guns as right now it is out of action.

 

[Jegwan]

I need parts for one of my "Aquatech" guns as right now it is out of action.

Hi Peter,
I still have some spares left - what do you need?
Jégwan

 

[popgun pete]

Thanks for the offer, but it is the sliding link arm to the trigger (pilot) valve which will be different in your gun compared with the one in my "Black Sea" gun. Made from plastic in order to keep its mass low, the angled peg on the bottom of this arm snapped off when I accidentally impeded the operation of the powered line release arm when conducting a routine test of the hydraulic trigger mechanism. The trigger pilot valve opening powers the line release movement, hence the actual plastic trigger hook secures the cam section of the line release plate that the line release arm is integral with as freeing up the line release plate is what causes the gun to shoot. Later guns use a different system, the version I have was only used for a short period as if the line release plate breaks the gun shoots, the plate being made of plastic.

 

[Jegwan]

Ok. I can't picture how that looks or works.
Could it be possible to make a new from an aluminium plate?
Jégwan

 

[popgun pete]

Yes, the parts could be made of metal, I was going to do that but never got around to deciding what to use. Although only the sliding link arm broke, the line release plate that it directly rubs on has to be made from the same stuff or there will be wear problems. How it works is the revolving line release plate is a cam shape that is secured by the top of the trigger poking up into a notch in its rear end, while just behind this plate and running directly above the trigger is a linking arm that functions as a cam follower that reaches back to the trigger pilot or control valve located rearwards of the trigger. This valve cannot open while the sliding link arm is held back by the cam shape on the rear of the revolving plate, but when you pull the trigger the cam plate is free to turn as the sliding link arm pushes on the plate as the control valve opens. That way the control valve causes the gun to shoot and swings the line release arm open at the exact same time as the revolving line release plate controls both actions. Thus the shooting line does not pull on the line release arm to open it, instead the arm swings open to let the line go, hence the line release action is powered by the hydraulic pressure in the gun, but using a very small diameter tube bore to reduce the actual force applied to the arm. If the gun shoots and the plate cannot revolve freely then the link between the plate and the valve breaks, which is exactly what happened. I had my finger in front of the line release arm, it was hit with little force by the revolving arm, but was enough resistance to snap the lower part of the sliding link arm that bears down on the top of the valve.

 

[EFISIO PIRODDI]

Ciao Pete , puoi mettere qualche foto del pezzo rotto? Grazie Efisio

 

[EFISIO PIRODDI]

Ciao Pete , NON BUTTARE VIA I PEZZI ROTTI perché li potresti dare a un ODONTOTECNICO e lui ti farebbe un pezzo uguale a quello rotto con il materiale che usano per costruire i byte ( usando una tecnica SOTTO PRESSIONE ).Ciao Efisio

 

[popgun pete]

I have not thrown away the broken pieces, but a recent burglary resulted in my digital camera being stolen, as well as my notebook computer and some other items. Right now I am using a borrowed computer, in fact I have only managed to get back on-line in the last couple of days. Unfortunately no more photos until I can buy a replacement camera. I will probably use aluminium to make the parts as stainless steel will be too heavy.