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Piston damper with liners

Jun 3, 2014
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#1
To increase the efficiency of the gun it is possible to reduce the diameter of the barrel to 9 mm under the harpoon 8 mm, but there is a problem with the piston stopping without damaging it! I solved this problem with the inserts in the piston damper together with the taper of the harpoon shank. The idea was developed under the valve gun with a light plastic piston.
втулка амортизатор с сухарями 001.jpg
 

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popgun pete

Well-Known Member
Jul 30, 2008
2,425
432
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Australia
#2
I recall seeing this muzzle system on “RPS-3” modification by you using "crackers" to catch piston after spear departs gun. Is this the same one? Only 1 mm difference in diameter leaves only 0.5 mm each side, so inward moving "crackers" increase the overlap with piston. Reaction time helped by taper on spear tail, but has this system proved reliable over many shots? Interesting idea as piston-less gun is in a sense gun with piston diameter the exact same size as the spear diameter which means higher pressure needs to be used in the gun. (Hydropneumatic gun is very similar, but has no piston while still possessing an inner barrel.) Conversely guns have large diameter pistons in order to increase force without changing pressure, all other things being equal. Of course they are not as changing inner barrel diameter has an effect on the compression ratio of the gun.

Just found image saved some years ago, so have answered my own question, image now attached. I was intrigued by your very novel idea, which is why I remembered it.
crackers.jpg
 
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Zahar
Jun 3, 2014
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#4
With this rifle, a lot of fish have been produced and the system has worked well! At present, the leader in efficiency are the guns Besporshnevka Vlanik! Why? 1. Friction minimum - 1 O-ring and minimum O-ring diameter 2. The ratio of the input volume of the harpoon to the receiver volume is minimum, and therefore F of the start of the shot approaches F of the end of the shot. 3. High pressure in the receiver allows you to save more potential energy of compressed air and to react less to changes in ambient temperature! My idea is to bring the indicators of a barrel - piston gun as close as possible to the indicators of a pistonless gun Vlanik!
 
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Zahar
Jun 3, 2014
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#5
Speaking of piston-less guns, what happened with this one as I wish to know more than what Vlanik indicated in another thread.
View attachment 52932
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Avtor Etogo ruzh'ya reshal problemu komfortnogo zaryazhaniya ruzh'ya i nadezhnosti yego raboty! K sozhaleniyu Sergey zabolel i umer ! Na skol'ko On uspel reshit' svoi zadachi k sozhaleniyu mozhno uznat' , tol'ko vzyav Yego ruzh'ye v ruki ! Tsarstviye Nebesnoye Sergeyu!
YA tozhe priobshchilsya k apgreydu Besporshnevki ! Poka yest' promezhutochnyy variant! No skoro zakonchu konechnyy variant s zatsepomgarpuna za probku, a probki za trigger bez naruzhnoy tyagi ! Dast Bog !

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The author of this gun solved the problem of comfortable loading a gun and the reliability of its work! Unfortunately, Sergei fell ill and died! How much He managed to solve his problems unfortunately can be found only by taking His gun in his hands! Kingdom of Heaven Sergey!
I also joined the upgrade Bosporshnevki! While there is an intermediate option! But soon I will finish the final version with a hook on the grun for the cork, and cork for the trigger without an external thrust! God willing!
 

popgun pete

Well-Known Member
Jul 30, 2008
2,425
432
123
Australia
#6
For some reason first two paragraphs do not translate, although a few familiar words are sprinkled here and there and the late inventor was Sergey (last name unknown for the present).
 

popgun pete

Well-Known Member
Jul 30, 2008
2,425
432
123
Australia
#7
Does a rubber "spring" propel the crackers inwards? I assume that they rub on the shaft as the tapered spear tail must force them apart during muzzle loading and then during the shot the spear moves past them. I guess the brass construction of the crackers allows a bearing surface on the steel shaft. The crackers need to close before the piston arrives, has the piston ever escaped? Many years ago a collet type line slide was proposed that was intended to catch on an annular notch in the shaft tail, the shaft tail having no stop diameter as such. The action of the collet closing was often too slow and the spear passed right through the line slide. Note that the muzzle shock absorber is on the body of the piston and the muzzle bore is the same as the shaft diameter, or very close to it.
John Salles line slide R.jpg

John Salles AIRMATIC.jpg
 
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Zahar
Jun 3, 2014
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#8
Bronze or brass liners glide very well on the surface of stainless steel! The length of the taper shank of the harpoon is calculated according to the maximum allowable speed of the harpoon from a pneumatic underwater gun 34m / s, which depends on the kinetic energy received by the harpoon during the shot and directly depends on the length of the gun and the loading force! Bronze inserts must have a constant contact of the taper shank of the harpoon due to clamping by O-rings! Compression speed 2 O-rings of bronze liners for difference of 8mm - 4mm = 4mm can be less than the speed of the harpoon with a sufficient length of the tapered part of the harpoon shank!

Stopping the piston due to the taper of the piston is a mistake! The cone length necessary for operation leads the piston length to an incommensurate distance for the gun to work properly! The taper should be only on the harpoon and of sufficient length!
 
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popgun pete

Well-Known Member
Jul 30, 2008
2,425
432
123
Australia
#11
In my opinion, this patent is completely stupid! When loading creates extra friction resistance and when fired, the friction is minimal and does not stop the piston! The piston is destroyed due to the minimum contact area with the front hub of the gun! I had a similar solution, but more effective!
This US patent, applied for in July 1955, is one of the first pneumatic speargun patents ever, so maybe not so stupid as you and I have the benefit of hindsight and experience of modern guns. The early pneumatic spearguns were evolving from the late thirties and forties era spring guns and even the "Airmatic" changed to a small sprung loaded ball (similar to socket spanner tools snap attachments) tail on the spear to connect with a matching recess in the piston nose. The line slide quickly evolved to a modern type that was caught by a stop diameter on the spear tail. Why I showed the patent was to illustrate that ideas for closing a variable opening to catch a small or nearly non-existent diameter change are not new, but were not considered reliable and soon discarded for production guns.
Airmatic speargun.jpg

As an interesting side note "Airmatic" guns were still being produced in recent times as the tooling for the guns was preserved according to Dave Sutton who provided these photos some years ago. An interesting feature is the piston seals are oiled leather washers which were what all the early pneumatic spearguns used before suitable rubber molded parts became available for the dynamic seals. "Airmatic" production numbers were low as the guns were very expensive and virtually hand made rather than mass production items.
 
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Zahar
Jun 3, 2014
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#12
Practice is a performance criterion! Paper tolerates everything! Many patents can be drawn on toilet paper! Algorithm of the invention in my opinion Idea - Calculation - Practice