A new auto and semi auto pcp system

[yousry]

Hi guys
today I am introducing a new idea for auto-semi auto system in pcp ,in my new design there is no recycled air no batteries no motors no electronics ,the system is a very simple one but very effective and cost less ,its idea depends on the well known phenomenon (the hammer bouncing )  which faces most of pcp makers ,in the new design and instead of trying to reduce the hammer bounce I magnify it to a degree that it can return the hammer back to be engaged by the trigger sear ,the design as you see in the drawings is very simple ,but it has some tricks such as the hammer weight and the spring powers ,the spring in front of the hammer is responsible for hammer return ,and we can shift from semi auto to full auto systems by the trigger sear mechanism , I did that mechanism myself but it still need some modifications like the magazine type I used the crosman auto indexing magazine but it was destroyed as it become empty the system needs a rotatory type magazine ,if any one is interested in my design we can do more discussion and try to modify it     thank you 

[Mod90]

The design is simple enough, but I'm not 100% certain it will provide a stable & reliable full auto feature. Semi auto would be possible though.
A better mag for this would be one of the hatsan aluminum mags, It's more durable & simpler. But that means you will have to re-engineer the breech, so the return force would also cycle the mag, instead of having the mag cycle the next shot via spring tension.

Also, the hammer spring could have a guide rod, that would go from the spring seat & got through the hammer, that would allow the hammer to travel in both directions & reduce some wobble that may eventually develop from metal friction wear. It would also serve to keep the hammer line up with the valve pin & not rely solely on spring tension.

Springs do lose tension over time, & this concept would have its hammer spring working 2x as hard as a typical knock open system, once to fire the round & the other to buffer the force of the hammer bounding back to the cocked position from the force return spring. Not saying it isn't doable, but high quality springs will have to be used, & a delicate balance found & maintained.

[Rescue35]

As described it will not work. You have described perpetual motion and if you get it to work you will be very rich once you apply it to producing electricity.

See Newtons laws of motion as well as the laws of thermodynamics.

[gabi.nechita]

I don't think it is a perpetual motion becouse it use air energy.
In this project it is hard to find a good balance betwen hammer mass, hammer spring and lenght of valve travel.

[Mod90]

It is essentially perpetual motion, no air or electronics being used to cycle or cock the gun or load a pellet, nor mechanical force, just energy stored & released in springs. It's basically one spring when compressed then released expressing enough energy to compress another, which will release & compress the first, & continue without stopping with the same force each time until stopped by an external force, in this case releasing the trigger so the sear could grab the hammer.

[kj]

it looks like he's using a pcp tube . each shot will have the force of the air to generate the initial movment. i think when he said , "no recycled air", he was refering to air from the shot being re-routed back to the magazine assembly. intresting idea.

peace
kj

[Rescue35]

I'm not trying to be negative Nancy, I just don't see this working without additional energy put into the cycle.

Lets say you have a 10 pound hammer spring (hs), a 5 pound return spring (rs), and 1 pound to open the valve (v). (Assuming a frictionless and over simplified environment)

The 10# hs will overcome the 5# rs and 1# v with 4# of force left over. 10hs-5rs-1v=4 extra energy. However the 5# return spring when coupled with 1# of force from the valve does not have enough energy to overcome the  hammer spring to return it to a latched position. 6-10 = -4 or 4 pounds of energy needed.

If you make the return spring strong enough to overcome the hammer spring, lets say 11#, there will not be enough energy to open the valve.
10-11-1 = -2 pounds of energy need to open the valve.

[rsterne]

I don't see it working as described, unless I'm missing something.... The air pressure is just providing a force against the valve poppet, the stem of which is resisting the forward momentum of the hammer.... In addition, once that air enters the barrel, not only is it accelerating the pellet, it is also resisting the forward momentum of the bolt.... Those two forces both act to decrease the energy and momentum of the hammer, damping the system and eventually bringing the motion to a stop....

Even without those forces, with just the hammer bouncing back and forth between the springs, friction would eventually bring it to a halt....

The only possibility I can see, assuming that the mechanism can be made to function, is that the air pressure working against the bolt face is adding to the rebound of the hammer each time the gun fires.... in other words, this is a blowback system with spring assist.... Isn't it?.... Therefore, part of the force of the air is being lost to cycle the action....

Bob

[Rescue35]

Much better explanation Bob. I did not see nor think of the force of the air acting on the bolt face.

[QVTom]

There is one way such a system may work in full auto mode.....  I say may because it looks to be a finicky tuning nightmare as well as many physical limitations.

If you put enough energy into the initial cocking and release you may be able to get the system to shuttle back and forth or a limited amount of cycles.  Each cycle would loose energy until the system could not open the valve and cycle the action.   Possible? probably; practical? probably not.

Tom

[johninthecamper]

crosman model 600 can do it on accident.all ten rounds in way less than a second

[gabi.nechita]

Maybe if bolt probe will get in the barrel 1-2 inch ,after fire ,bulet will be push forward and bolt and hammer backward with enough force to make reload ( I hope).

[rsterne]

The only way the system can keep working (full auto) is for there to be an input of energy, or each hammer strike will be less than the last, and the velocity of each shot will drop until it stops cycling.... The valve stem, while it can supply energy to the hammer on the return stroke, will take more energy to open it on the next cycle.... The only source I can see for that energy is the air pressure on the nose of the bolt, making this effectively a "blow-back" system....

Bob

[QVTom]

Looking more carefully at the pictures there is no locking of the bolt in battery; it is a blow backs system as presented.  Blow back systems used in 22LR work well but have much more energy to work with.  Air would be a challenge to get a workable efficiency.


Tom

[yousry]

thank you so much for your nice and useful replies ,actually I am neither  a mechanist nor an expert in pcp making also I don't know much a bout the laws of dynamics ,I am a doctor specialized in bone and joint surgery ,and my hobby is pcp making and tuning  ,I did some models (rifles and bull pup ) but I discovered the auto system accidentally while I was trying a heavy hammer in a model ,the hammer bounce was so hard that it make several valve strikes ,that is why I put the spring in front of the hammer but it was so strong that it returns the hammer back to be engaged by the trigger sear ,the hammer weight  was about 125 gm  and the spring wire was 2.5 mm ,then I put the breach and I made the bolt long enough to keep air from escaping back ,  I don't know exactly how it works but it was surprisingly works ,its not a blow back mechanism because if you remove the bolt the system will still work ,I know it needs a lot of modifications ,that is why I am introducing it for you as experts to develop it ,thank you     

[rkr]

The extra energy needed comes from the air pressure acting on the pellet probe. It's not a bad idea but it will blow air out through the magazine. A vent right at the beginning of the barrel directed away from the shooter would be a good idea. I actully had similar phenomenon at work when I tuned my Scorpion. When power was increased enough the bolt popped open and started retracting. Not enough to cock the gun but with some fine tuning of dimensions and weights that should have been possible.