Vlanikgun

[Vlanik]

All regard!
Long ago read your forum...
Want to introduce you with their own undersea handgun...
Ïîäâîäíûå ðóæüÿ Vlanik

 

[popgun pete]

Hi Vlanik, I see that your speargun now has a new grip handle, the guns look very good in the photos. Do the guns still have no inner barrel or are you using the perforated inner barrel? Some years back we talked about a "turbine piston" with fins.

 

[Vlanik]

Спасибо за оценку!
Тяга спуска, на всех ружьях ставится с низу...
Поиск универсальной рукоятки, всё ещё продолжается...

 

[popgun pete]

Спасибо за оценку!
Тяга спуска, на всех ружьях ставится с низу...
Поиск универсальной рукоятки, всё ещё продолжается...

I had a closer look and saw that it was the reflection on the side of the outer barrel, that is why I amended my post, however you have replied at about the same time as I changed it.

 

[Vlanik]

Привет Пит!!!
Как мир тесен...
6 лет прошло, а как вчера...
Ты молодец!!! И почти тогда угадал...
Èñòîðèÿ áåñïîðøíåâûõ ðóæåé
Я пересчитал влияние гравитации на внутреннюю баллистику...
И вновь отказался от ствола...

 

[popgun pete]

The "Vlanik" pneumatic spearguns are forward latching types, the sear installed in the muzzle holds onto a notch in the spear shaft just behind the projecting end of the shaft and speartip. The muzzle loaded shaft passes through a seal in the muzzle and its entry into the gun displaces a volume of pressurized air inside the reservoir equivalent to the volume of the body of the shaft. An analogy would be the "RPS-3" where the shaft displaces water inside the inner barrel and that in turn displaces a volume of pressurized air inside the surrounding compressed air reservoir. Therefore a "Vlanik" gun with an 8 mm diameter spear functions as if it had an 8 mm diameter inner barrel in terms of the propulsive force on the shaft.

As the "Vlanik" gun has no inner barrel there is no water filled barrel or air flow restrictions inside the gun to impair its operating efficiency. With only one dynamic seal, the one in the muzzle directly behind the sear, frictional losses are at the lowest possible. A detachable spear tail cap never leaves the gun as it serves to plug the inner end of the muzzle and thus stops air pressure escaping through the muzzle as the spear exits the gun. The tail cap's cylindrical surface takes over the air sealing duties from the spear shaft's surface provided that the join between them is effectively seamless.

 

[popgun pete]

Back in 2005 I wrote to Vladimir ("Vlanik") about an idea to make a dual power version of his gun. This involved fitting a tube inside the gun something like an inner barrel with an open rear end. This rear end could be closed by operating a dial on the rear end of the gun to advance an internal plug that hermetically closed off the open end of the inner tube. The concept was that you loaded the gun and if you wanted to use low power then you closed the rear of the inner tube and utilized only the expansion of the air in the inner tube to shoot the shaft from the gun. Air in the space between the outer body and the inner tube remained at the "charged to shoot" pressure. To avoid the spear tail cap/muzzle plug falling off inside the gun it was equipped with eight small fins that could skate along the internal surface of the inner pipe, these fins also restraining the tail cap/plug when it struck the rear of the muzzle. Hence the term "Turbine Piston". Thin triangular cross section fins were required to avoid the possibility of any air pumping inside the inner tube which would slow the shot and possibly pull the tail cap off the end of the shaft before it reached the muzzle, resulting in a total loss of pressurized air! What I failed to do was calculate the pressure reduction for the shot at low power, Vladimir indicated that the reduction was not worth the added complexity. When I did work it out the figure was about a 10% reduction, so the shot would be at 90%. To produce a lower figure the inner barrel would have to be much smaller in diameter, in which case the "turbine fins" would block off too much air flow and would have to be eliminated. The flange on the rear of the tail cap could start to pump air in a smaller diameter inner tube and as a certain flange size is required to stop the tail cap at the muzzle when it serves as a plug, removing material from the flange to improve air flow in the inner tube and avoid pumping effects would present other problems. I did not know that Vladimir had been considering an inner tube to function as a guide, but with the inner tube perforated to prevent the pumping action which I have described above. As he indicates (use Bing to translate these Russian language posts with a right button click after selecting the relevant text) this internal modification was more likely to cause a deterioration in the gun's performance rather than any improvement.

 

[tromic]

I've just looked at the pictures and drawings of Vlanik. I like it! Nice and simple solutions. Interesting solution for line release too.:friday

 

[popgun pete]

I've just looked at the pictures and drawings of Vlanik. I like it! Nice and simple solutions. Interesting solution for line release too.:friday

The design certainly suits a very slim pneumatic speargun as there is no need to accommodate anything inside it except the spear shaft. It should be a quiet shooter as only the spear tail cap striking the back of the muzzle when it parts company with the spear will make any noise.

 

[tromic]

The design certainly suits a very slim pneumatic speargun as there is no need to accommodate anything inside it except the spear shaft. It should be a quiet shooter as only the spear tail cap striking the back of the muzzle when it parts company with the spear will make any noise.

I suppose it is on about 50 bars to get 25 kg loading effort.

 

[popgun pete]

Here is a review by Hanter Fishgun - Ñàìîäåëêè

 

[Vlanik]

I suppose it is on about 50 bars to get 25 kg loading effort.

http://vlanikgun.narod.ru/Vlanik.xls

 

[popgun pete]

I suppose it is on about 50 bars to get 25 kg loading effort.

According to the Vlanik Excel spreadsheet the pressure is 49.74 atm, so about 50 Bar as you say. I was curious about the compression ratio of such a small internal diameter reservoir speargun. This can be easily calculated if we assume that the working course of the spear is the full length of the air reservoir, i.e. the spear tail cap touches the rear wall of the reservoir when the gun is cocked so that we can ignore any volume of air sitting immediately behind the spear tail. The compression ratio is given by the air volume of the reservoir before introducing the spear divided by the final air volume after the spear is latched in the gun. As this is a ratio of volumes we can eliminate the value of pi and the reservoir and internally projecting spear lengths from the calculation as they appear in both the top and bottom lines of the resultant fraction and can thus be cancelled out.

Therefore Compression Ratio CR = D*D/(D*D - d*d) where D is the internal diameter of the air reservoir and d is the diameter of the spear shaft. An alternative formula by simple manipulation is the inverse of CR = 1 - (d/D) squared. The "Vlanik" gun has D = 19 mm and d = 8 mm which produces a compression ratio of 1.215. A "Sten" type pneumatic speargun has a compression ratio around 1.10. So if a "Vlanik" pneumatic speargun was say pressurized to 50 Bar then once cocked it would be at (1.215 x 50) which equals 60.75 Bar. Alternatively if it was at 50 Bar when cocked then the initial charge pressure would be (50/1.215) which equals 41.15 Bar. The pressure increasing as you push the spear into the gun progressively increases the effort required, the most force being needed at the point of latching the shaft.

 

[tromic]

Peter, I've read the review (Bing translation) but hardly can understand it, pros & cons. Can you point out some cons? Pros are obvious. I suppose that review was for some older model of Vlanik? The effective length of this gun is excellent. For any length of the gun the effective length is only 5 cm less. For Cyrano it is about 20 cm. For Airbalete maybe 25 cm. Under the effective lenght I assume the acceleration length of the shaft.

 

[popgun pete]

The "Vlanik" gun examined by Hanter had some quality problems in terms of machining of the large screw threads and alignment of parts, but it appears that this is now fixed. Trigger and sear also required some adjustment.

Pros are the gun is powerful due to the extremely high efficiency, better than any other pneumatic powered speargun! Components are the minimum number required, however the "Vlanik" gun has no buoyancy, but most pneumatic guns with small diameter reservoirs do not float anyway. Small size allows good underwater handling characteristics, plus grip handle can be located anywhere on the gun by the manufacturer.

Cons are all involved with the transition of sealing and any gaps between the spear surface and that of its detachable tail cap and the necessity of a very accurate alignment at the muzzle with the tail cap sitting on the rear of the shaft. If the tail cap does not hit the rear of the muzzle squarely then it can be pulled off the shaft prematurely and the compressed air will all escape. The shaft must be very straight so that when inside the gun it remains concentric with the surrounding reservoir, remember that only the muzzle bore controls and guides the shaft. The gun is intolerant of any grit entering the muzzle, any subsequent scratches on the shaft will cause damage to the muzzle seal necessitating its replacement as the gun will not hold pressure otherwise. The shaft surface must be completely blemish free. The action of the sear tooth can damage the shaft surface if you do not continue to pull the trigger during the loading of the gun, but this depends on whether the cylindrical sear's tooth has any sharp edges which will damage the shaft. Each shot of the gun allows a small amount of air out as the muzzle seal is transitioned by the shaft join at the shaft tail cap connection and on muzzle loading this occurs as well, but the amount is minimal if the parts are correctly manufactured and maintained. A small amount of water can be caught between the interior of the tail cap when it is pressed onto the shaft and needs some pathway so that most of it can be squeezed out in the muzzle before it is transported through the muzzle seal into the gun's interior during shaft loading. Grit in this area cannot be tolerated as it prevents the critical gaps closing up on the shaft to tail cap connection.

Thus everything depends on the gun being well engineered and accurately constructed, not an onerous requirement considering the very small number of parts. The user needs to observe cleanliness requirements with regard to contaminants getting inside the muzzle and keeping the actual shaft tail in good order so that it couples effectively with the shaft tail cap located inside the gun.

Another good reference is found here which elaborates on the above and offers some possible solutions. http://www.fishgun-master.ho.com.ua/proekt_vlanik.htm A shorter gun seems better suited to this system as there is less weight to deflect the unsupported shaft length inside the gun, but this is something best answered by Vladimir.

 

[tromic]

Thanks Peter! Is there a possibility for shaft tail cap to fall down (be separated) from the shaft, before or during the shooting? Is there any lubrication necessary to prevent damage of O-ring in the muzzle.

 

[Vlanik]

Многое поменялось за 6 лет...
Применяются иные технологии и материалы...

Ружья стали лёгкие и все плавают...

 

[Vlanik]

Thanks Peter! Is there a possibility for shaft tail cap to fall down (be separated) from the shaft, before or during the shooting? Is there any lubrication necessary to prevent damage of O-ring in the muzzle.

 

[Vlanik]

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Спасибо за подсказку...
Если вы считаете что я провожу тут рекламу, то можете удалить мои сообщения...
Я пришёл к вам, показать что есть и другие направления в пневматических ружьях...
На ваши вопросы отвечаю лиш потому, что вы ищете ответы у тех кто никакого отношения не имеет к моим ружьям...
Эти люди не могут обяснить на каких принципах происходит работа ружей...
Они не способны просчитать, смоделировать, сделать и провести баппистические тесты...
На этом я с вами прощаюсь.

 

[popgun pete]

Thanks Peter! Is there a possibility for shaft tail cap to fall down (be separated) from the shaft, before or during the shooting? Is there any lubrication necessary to prevent damage of O-ring in the muzzle.

Well Vlanik says a lot has changed in 6 years and the guns now float, so the metal bulkhead parts must have changed to plastic. Looking at the latest photos we can see these parts much better. The guns always had oil inside for lubrication, that is also mentioned on his web-site. Now that the guns float after spear discharge the chance of picking up grit is greatly reduced. As Vlanik says, you are asking about info from people who do not have his guns, but I have been hoping that he would tell us more himself. Looks like he is not continuing here judging by his last post, but I hope that he reconsiders this decision. As to the tail cap falling off inside the gun I doubt that is a problem as there was a friction device holding it on in the past and there appears to be some items on the tang at the rear of the shaft in these latest photos. Hopefully Vlanik might show us a close-up of the shaft tail parts. I wonder what the prices are like, could be an interesting gun to try out.