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Wagria recoilless air pistol patent 1951


Garvin
(@garvin)
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Wagria recoilless air pistol patent 1951 

This patent predated the patent by Kurt Giss for Dianawerk by two years. It apparently never went into production, but it's possible there is a working prototype out there somewhere.

This patent was uncovered by the researches of Encyclopedia of Spring Air Pistols author John Griffiths, first revealed on the airgunbbs.com.

John said: "All the literature on air gun development in the twentieth century attributes the concept of the two-piston recoilless system to Kurt Giss, the Chief Designer for Dianawerk, and to Dianwerk itself. The earliest Giss patent dates to December 17, 1953, although it was not granted until 1956. However, when I was going through some rather obscure German patents that had been kindly sent to by a well known German collector, I spotted something very surprising. I found what appeared to be direct evidence that another company had patented the principle two years earlier, in 1951.
I wonder if that is why it took four years before Dianawerk got their patent granted? Perhaps there was a legal dispute and some sort of protracted financial negotiations between the two companies took place?

"The first (1953) Giss /Dianawerk patent shows two designs for the recoilless two-piston system airgun, both of which show the pistons moving towards each other.

 

"The second Giss patent (1956) covers the commercially favoured design where the two pistons move away from each other:

 

"The patent which turns history on its head and predates the 1953 Giss/Dianawerk patent is shown below. It was applied for by the German company “Maschinen- und Apparatebau G.m.b.H Wagria (based in Ascheberg, northern Germany), and the application was made some two years before Dianawerk, in 1951. This is the patent and you can see that the patent illustration is for a pistol in which the two pistons move towards each other. The illustrated pistol shows a neat way of how the two pistons can be simultaneously cocked with one stroke.

"Not very much has been written about the “Maschinen- und Apparatebau G.m.b.H Wagria” company, but we do know that it made a range of air rifles in the 50‘s and 60’s, usually marked “Wagria”, which are quite rare. You can see some of their products in the Gallery here: https://forum.vintageairgunsgallery.com/wagria/

"What a find it would be - a Wagria prototype recoilless air rifle from the pre-Giss period! I suppose it is always possible that Giss worked for Wagria and then moved to Dianawerk, so he would then still be the originator of the concept. For some reason Wagria did not list the actual inventor’s name on their 1951 application, so we may never know.

"One of the reasons why the Wagria patent has been overlooked all these years may be because the German patent office (Depatis) only stored the first page of the patent in their online files. Not only did this page have no illustrations, but the original text was typed on a manual typewriter and was very indistinct. Depatis scanned the typewritten page and fatally machine-converted the text to digital form, giving an online pdf which can best be described as gibberish. So even if during a Depatis search you turned up the patent and was interested in it from its from its title, you would have no idea what it was all about from the online pdf. To find the patent in its complete original typewritten form with illustrations you would have to search on Espacenet, the European Patent Office website.

"I have deciphered the typewritten test of the original and translated it into English and it makes interesting reading. It makes it clear that the objective of the two pistons is to minimise recoil, and it also suggests that the pistons can be arranged to move away from each other as well as towards each other to achieve this effect. It also covers the possibility of using the concentric barrel/piston principle with the two-piston systems, so it covered all bases.

"So, to conclude, it seems that Giss was not the first to come up with the idea of the two-piston recoilless system (although it is just possible he might have been if he had worked for Wagria in 1951). But we can be sure that Dianawerk was not the first company with the idea, contrary to what the history books (and their own website) say."

Subsequently there was discussion on the airgunbbs.com, that went:

Danny Garvin: "Am I right in thinking the pistons were not synchronised mechanically but relied on a simultaneous sear release instead?"

John Griffiths: "The patent claims (somewhat optimistically) that "the sear mechanism ensures that both pistons are released simultaneously". Otherwise it makes no mention of ways of ensuring synchronisation. I suppose that for a small pistol where extreme accuracy is not intended it will not matter if the pistons are slightly out of sync as there will always be some internal compensation of the relative rates of travel of the pistons as they get closer and closer together. After all, the air is going to get out of the cylinder and up the barrel whatever the timing of the pistons (within reason, assuming identical springs and compression distances)..."

Shed Tuner, a BBS regular who is expert in airguns said: "The problem is, if the timing is only a fraction off, the peak pressure falls off a cliff. Literally, 1 mm off, and the "dead volume" increases 3x fold, so that's a third of the pressure. 5mm or more is a more likely scenario, so we are talking a 15th of the pressure. The pellet would barely leave the barrel."

JG replied: "I think I see what you are saying if by "peak pressure" you mean that the pellet is a tight fit in the barrel and the peak pressure is when the pressure has built up to a high enough critical level to get the pellet to move. But you don't always need to have a tight fitting pellet to get reasonable muzzle velocities. I have several vintage pistols which, probably with far from perfect piston seals, are useless with tight fitting pellets, but give a good account of themselves with pellets that have been resized to an easy sliding fit in the barrel.

"So while out-of-sync pistons would not be an ideal scenario for a high performance gun, I don't think it would be quite as bad as the pellet barely leaving the barrel."

ST: "Nope, you've misunderstood... although your definition of peak pressure in a conventional firing cycle is fine; probably my crap explanation to blame! Nothing to do with pellet fit. If the pistons don't meet correctly in the middle, the pressure that may make reduces exponentially."

JG: "In that case I am still a bit puzzled. If the springs are of equal strength and length then the pistons will always eventually come to equilibrium in the centre of the cylinder, with all the air expelled. You can't get a situation where one piston has traveled past the exit hole and the other hasn't reached it, and there is a volume of compressed air permanently trapped in the cylinder. (Though you could if one spring was longer and stronger than the other).

"If there is a mismatch with the timing I imagine there would a transfer of energy from one spring to the other from the building-up air pressure as they travel towards each other, in a kind of shuffling process, until they finally end up in contact at the centre with all the air expelled.

"But you could be right. I imagine that technically this is a very complicated process (and very interesting) and the only way to sort it out would be to make an example of the pistol and road test it. As a result I have moved it up my priority list of projects!..."

ST:
 
Quote Originally Posted by JG View Post
"If the springs are of equal strength and length then the pistons will always eventually come to equilibrium in the centre of the cylinder, with all the air expelled."

ST: "Agreed - eventually - but only if they are 100% balanced will those pistons be stopping in line with the tp, as opposed to a mill or two either way,

Quote Originally Posted by JG View Post
"You can't get a situation where one piston has traveled past the exit hole and the other hasn't reached it"

ST: "I think you could... unless something is stopping the pistons going past centre.

Quote Originally Posted by JG View Post
"If there is a mismatch with the timing I imagine there would a transfer of energy from one spring to the other from the building-up air pressure as they travel towards each other, in a kind of shuffling process, until they finally end up in contact at the centre with all the air expelled."

ST: " "Yup, that seems reasonable too."

Quote Originally Posted by JG View Post
"But you could be right. I imagine that technically this is a very complicated process (and very interesting) and the only way to sort it out would be to make an example of the pistol and road test it. As a result I have moved it up my priority list of projects!"

ST: "Ha, would love to see it. I think a cylinder end wall (in the centre) might be needed if you can't synch them."

 


   
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Garvin
(@garvin)
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Joined: 5 years ago
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Wagria recoilless air pistol patent translation 

With thanks to John G for this English translation.

 




   
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