Pelengas Pneumovacuum speargun

[Nico66]

And the reel is the pelengas new model.

 

[popgun pete]

And the reel is the pelengas new model.

https://www.ebay.com/itm/Univrsal-R...261042?hash=item1ef74126f2:g:jQ8AAOSw2EJck1Ku
As seen here. Now available for purchase from Pelengas Store. In fact I just purchased one, so 9 reels left!

 

[popgun pete]

The reel has arrived, it is a little bit smaller than I thought it would be, but is big enough. Very light construction at 95 grams, including its mounting plate.

 

[Diving Gecko]

I might have missed it, but @Pete can you tell me how the Pelengas assembles at the front? Does the muzzle screw onto a thread on the barrel like on the Italian guns? I think it does, but I am asking because I have seen some of the Russian guns where the nose cones, and not the muzzle, screws into the front of the reservoir. Also, in case you did measurements, I would be very interested in how the SS steel barrel looks. I know it's 11.9mm ID but what's the OD at the front (where the thread presumably is)?

 

[popgun pete]

Guns where the nose cone screws into the tank don't use the inner barrel to hold the gun together as they are valve trigger guns (there are some exceptions) and the barrel is not extending from end to end of the gun. The "Pelengas" pneumovacuum guns have muzzles that screw on the inner barrel just like any of the Italian Mares, Cressi and Salvimar guns. The stainless steel barrels are stronger so can use smaller threads, but the outside of the barrels does not look to be machined down on the “Pelengas” guns. I have not checked the thread size, but all the kit muzzles for other guns (Italian) will suit their individual muzzle threads. Note no rear inner thread on the "Pelengas" gun as they use a transverse pin at the rear to hold the back end of the gun on the inner barrel.

 

[Diving Gecko]

Thanks Pete,
Maybe it's 11.9x16mm, then. Supposedly, when some of the modders use 12x14mm SS barrels they sleeve the ends. I heard it was not only to be able to use original parts made for larger OD barrels but because they don't trust that a threaded 12x14mm barrel is strong enough at the threads. But that confuses me a bit as I would think the sleeves are threaded onto the 12x14mm barrels, too...?
Maybe @Nico66 would know?

 

[popgun pete]

The screw threads in stainless steel barrel tubes can be quite small in terms of the thread depth, just look at the tiny threads in the "Taimen"! However a smaller cross-section of the gun takes the pressure trying to blow that gun apart, about 26 mm ID, compared with 38 mm ID on a "Sten" or a "Cyrano". If people want to switch the inner barrels then they will want to match existing threads and reduce weight by turning down the outside of the barrels where they don’t touch anything. A lot depends on the stock stainless steel tube sizes available, some of the more oddball sizes may be for other purposes and being available that is what manufacturers have used.

 

[Diving Gecko]

Yeah, me asking this question is in preparation for a scratch build I am still hoping to get underway. So, just checking how people do it.
I remember seeing a very thin walled titanium cylinder with internal screw threads for a PCP airgun - and they hold about 200 bar. Can't remember how thin, but it was surprisingly thin.

 

[popgun pete]

Yeah, me asking this question is in preparation for a scratch build I am still hoping to get underway. So, just checking how people do it.
I remember seeing a very thin walled titanium cylinder with internal screw threads for a PCP airgun - and they hold about 200 bar. Can't remember how thin, but it was surprisingly thin.

Titanium is very expensive, you want to use it only where you cannot use anything else, particularly titanium tubing. The larger diameter tank "Black Sea" guns used it so that they were not going to blow up! Wherever rubbing is involved it is not used, such as inner barrels as that is a job for stainless steel.

 

[Diving Gecko]

In other Pelengas news, judging from a dive show video from 2019 that I can't find right now, they changed the muzzle a tad.
It has a longer front part now:

The muzzle has also "grown" a thin-walled inner lip supporting the inside of the conical cuff (like the original from Dima has and like Vuoto does, too):

Pelengas seem to have left that inner lip out in previous versions:

But here's a nice invention from their side - they are using the inside of the inlet valve cap to store a replacement cuff:

In that same video there was also some footage of the carbon fiber barrel but it was probably just an early prototype as the finish looked pretty amateurish.

If I find the link again, I will post it.

 

[popgun pete]

That new muzzle looks like the one on the "Pelengas" carbon pneumatic gun, so they are fitting it to the other models would be my guess, or at least some of them. The inlet valve cap on their guns has up until now been a threaded plug or disk with a shallow curved screwdriver slot in it that really needs a coin to undo it. If you use a screwdriver then the slot will soon tear up as the threads are rather tight initially because the molded disk is a trifle big.

 

[popgun pete]

The new inner lip is probably to ensure concentricity of the vacuum cuff when you tighten the front cap up. The smart way to do it is with the gun cocked and ready to shoot you loosen the plastic cap, which has the line slide stuck in it and retighten it, then the vacuum cuff will be properly lined up. You do this with the gun not in the water, but pointing downwards for safety reasons, or you let all the air out first. On the "Taimen", which "Pelengas" forgot to copy in this respect, the vacuum cuff alignment is taken care of by the conical seat for the cuff inside the front hub.

 

[Diving Gecko]

That new muzzle looks like the one on the "Pelengas" carbon pneumatic gun, so they are fitting it to the other models would be my guess, or at least some of them. The inlet valve cap on their guns has up until now been a threaded plug or disk with a shallow curved screwdriver slot in it that really needs a coin to undo it. If you use a screwdriver then the slot will soon tear up as the threads are rather tight initially because the molded disk is a trifle big.
View attachment 54703View attachment 54704View attachment 54705

At least towards the end of this video, the new muzzle is shown on a smaller gun with the regular hydroformed alu reservoir:


(This is the video I couldn't find when I wrote the previous post. It has footage of some CF guns, too though one is just hanging on the wall)

 

[Diving Gecko]

The new inner lip is probably to ensure concentricity of the vacuum cuff when you tighten the front cap up. The smart way to do it is with the gun cocked and ready to shoot you loosen the plastic cap, which has the line slide stuck in it and retighten it, then the vacuum cuff will be properly lined up. You do this with the gun not in the water, but pointing downwards for safety reasons, or you let all the air out first. On the "Taimen", which "Pelengas" forgot to copy in this respect, the vacuum cuff alignment is taken care of by the conical seat for the cuff inside the front hub.
View attachment 54706

Just speculation, but I am thinking that without the lip - or by loosening and then tightening the front when loaded in a lip less design - there's a risk that the cuff will be pulled towards the gun by the vacuum. I guess the same can happen at depth from the pressure if the foot of the cuff is not well supported.
I know @tromic feels it is definitely happening at the top of the cuff already and might lead to excessive friction and explain why these seals tend to be ripped. I think I agree with Tomi on the fact that the top probably collapses onto the shaft, but so far it's a price I am will to pay for the ease of using this type of seal. But I am thinking about the foot here, only in terms of the missing lip.

 

[Diving Gecko]

I have spent a bit of time looking at Russian/Ukranian guns the past few days and this Ukranian shop keeps popping up. They look big, well stocked and with a big online presence, so if they are will to ship internationally, they might be an option:

Ружья для подводной охоты Pelengas купить в магазине KatranGun

katrangun.com.ua

 

[Diving Gecko]

So, I did a bit more digging and it seems like Pelengas has had other ways of supporting the foot of the cuff.
I am not entirely sure of the timeline but possibly back in 2015, they changed to this new kind of seal that has a channel on the front/top of the foot which seems to be supported by a protruding lip from the rear of the front part of the muzzle:

 

[Diving Gecko]

BTW @popgun pete Did you talk about where the name Pelengas came from? Or perhaps it was the Taimen, you talked about a fish with that name.
Well, for the Pelengas, I guess it is a mullet.
Perhaps the red-lip mullet or Liza haematocheilus in latin.

As for that lipped front part of the muzzle holding the newer (?) cuff in place, the channel in the cuff can even be spotted on this older diagram Pete put up back on post #25:

 

[Diving Gecko]

I might have missed it, but @Pete can you tell me how the Pelengas assembles at the front? Does the muzzle screw onto a thread on the barrel like on the Italian guns? I think it does, but I am asking because I have seen some of the Russian guns where the nose cones, and not the muzzle, screws into the front of the reservoir. Also, in case you did measurements, I would be very interested in how the SS steel barrel looks. I know it's 11.9mm ID but what's the OD at the front (where the thread presumably is)?

As for the barrels, I did some more digging and it seems Pelengas use both alu and stainless barrels depending on the guns.
For now, I would say the alu version is 12x16mm (ID x OD) but I found a mentioning of a stainless steel barrel being 12x14mm with a front thread of M14x0.75.
I think it makes sense to go with a smaller pitch on the thread as it means the thread isn't cut as deep into the wall as higher pitch thread would be.
Oddly enough, the gun in question has an "Italian type" screw-in pump inlet valve for which they are going with an M13x1mm thread:

Огляд рушниці Пеленгас Еко 2017 р.в.!

Огляд рушниці Пеленгас Еко 2017 р.в.!

katrangun.com.ua

P.S. I am not sure of that 11.9 vs. 11.99 vs. 12mm inner barrel size. Some say 11.99mm, some say 12mm. Maybe it is the former but the latter being used for simplicity.

 

[Diving Gecko]

Here's a nice cutaway pic of a Pelengas muzzle. Seems like the only way to actually get the shock absorber into it is by depressing or folding it in on itself as the threaded part at the rear seems smaller than where the shock absorber sits, so one more possible explanation to why it is so soft?:

Though in this longer version with three PU elements, perhaps that issue looks less severe?

Two things I learned: it's hard to get a proper timeline on all of this - I think the company is constantly developing and trying out new things. And also, the boss (?) does seem to have a proper presence on their forums in Russia and Ukraine and seems to not mind sharing his thoughts and prototypes - he may even be listening to the feedback

 

[popgun pete]

Pelengas is a Mullet, the Grey Sea Mullet is a prized fish in that part of the world, the sea I expect being the Black Sea. The Taimen is a Siberian Salmon and can be a very big fish, is also highly prized and had to be protected from those who would catch the lot of them if they could! There must be a bucket of money for Pelengas to make all these models and changes in a relatively short period. My Magnum 70 is currently depressurized, so I will drag it out of my storage area and check that plastic cap. Bear in mind that Pelengas took their starting ideas from Taimen, there is no doubt of that!