Small autonomous hybrid

[hectmarr]

Yesterday I did the corresponding tests. The system works perfectly but the firing power is poor.
I tested with 1/4 "and 5X steel balls, and the power is about half or one third, (1/2, 1/3), of what is achieved with that compression pressure and a rupture disc.
The reason is that much of the available energy generated in the mechanical work of compressing the spring, which is very hard, is spent. This is necessary so that the exhaust hole is not opened when compressing the mixture.
It shoots well, it is more powerful than a combustion weapon for ammunition of that caliber, but even in dreams the power of firing a hybrid can not be reached with a simple rupture disc, for that same firing cannon and that ammunition.
Logically, the energy used to break the rupture disc is many times less than that necessary to move the mass of the piston - guide - spring system, against the force exerted by this spring that is compressed.
In summary: Very simple to manufacture, easy to regulate, but with little force available to boost the ammunition.
Interesting experiment.
What remains to be proved is to minimize the mass of the piston assembly and the guide rod, and to leave the minimum and absolutely necessary force in the mainspring to be able to compress the mixture without opening the exhaust hole. I'll try this and tell you.

[hectmarr]

I was doing some tests and corrections to this system for hybrids.
The piston was separated from the spring guide rod, it no longer has it, and the weight reduction of the piston is large. Before, it weighed 139 gr, and now weight, 28 gr. The shank was an iron 20 cm long by 11 mm in diameter, very heavy. Immediately the thing started to work properly, producing a small powerful and dry explosion, as happens with the other small hybrids I have with a rupture disc.
The bottom issue is to regulate how far the piston should go when the mixture is compressed, "A" in the diagram, I mean, the distance to the exhaust hole, "B" ..
If it is too close, the piston opens the exhaust hole very early, and the maximum pressure never occurs. The result is a blow only. Otherwise, if the piston is some distance from the exhaust port, the maximum pressure peak during combustion if it occurs, and everything behaves as if it had a rupture disc.
I used a single 100-pound spring to hold the piston during the compression phase of the mixture and to return the piston and clean the combustion chamber after firing. The diameter of the combustion chamber is of 3 cm and when it is with programmed pressure of mixture, it has 6 cm of length, the volume is about 40 cm3. Burns 7 cm3 of butane, for 160 cm3 of air at 4 bar.
In this test weapon, I used a commercial 5.5mm spout with grooves.
I will prepare a small video of the experiment to see it work. It's interesting for me, not to make more rupture discs. It's simpler to just load the ammunition alone.
I have to get a harder spring, 150 pounds, to take it to 7 or 8X. Currently shooting at 4X.
In summary, it works perfectly without energy losses, although it requires some calibration work to synchronize the opening of the exhaust with the maximum possible peak pressure. It is very simple to build, and the only thing that must be taken care of, is not to leave burst in the exhaust hole that is 4mm, so as not to destroy the o'ring.

[jackssmirkingrevenge]

Looking good! Is the port sealed by the piston significantly smaller than the piston diameter, to give a pop-off effect?

[hectmarr]

Actually, the diameter of the hole that I used for this test is by the oring, and because it is very similar to the other two .22 caliber weapons that I built. These are the two reasons.
The first.
The oring has a diameter in its sectional cut of 3mm, and if the exit orifice is larger, the oring is damaged ....
The solution, if necessary, I think it is not necessary, is to drill 5 or 6 holes, (or the necessary), about 1mm, around the combustion chamber and attach an outlet that collects the gases of all holes and eject them by one. All these holes added, should be equivalent to a large exhaust hole, but each, not more than 1/3 of the sectional diameter of oring. In this way, it will not be damaged.
The second.
In the other small hybrids, the output port is no more than 5.5mm. In the place where the rupture disc they use, the output is 5.5mm because the ammunition is there, which is the port of departure, based on this empirical information, use something similar in this test.
What I like is that it can be regulated with the force of the spring, the moment in which the exhaust opens, only adding or removing some washers to compress more or compress less the spring, in relation to the longitudinal position of the exhaust hole that is fixed.
It is the only way to explain that using 6X the weapon has less power than with 4X, which is what I observed in the tests.
This happens because in the case of compressing to 6X, the piston is very close to the exhaust hole because the spring is more compressed by the higher pressure, and the outlet port opens before the pressure peak, not allowing this peak Maximum pressure is realized. In the case of compressing to 4X, the piston is further away from the exhaust hole, because the spring is less compressed by having less pressure, and giving time to the mixture when it explodes, to achieve maximum pressure just when the orifice is opened. departure. I do not see another explanation for what was observed in the facts.
The lengths traversed by the piston regulate the system time. More route, more time and in reverse, all this taking as reference a fixed point in the considered trajectory, in this case, which is the exit hole.
 The pressures that are used are in direct function with the strength of each spring. The mass of the piston for a given force, logically, also influences the time. A more mass, more time, and vice versa.

[hectmarr]

4X shot test that is as far as the spring I have.
The "weapon" is only to be able to shoot safely, outside of my workshop, because it is very noisy. I will try to make a basic silencer.
I am almost determined to use this valve integrated to the burned gas scavenging system, for the semiautomatic.
It has the same power as the first autonomous hybrid, with the difference that this hybrid cartridge with bursting disc burns 13 cm3 of gas and this, the video of the test, 7cm3.
Dejo un par de fotos.
[youtube][/youtube]

[farcticox1]

will this be in the competition ?

[hectmarr]

will this be in the competition ?

I do not think so. It is a simple test, not a finished weapon, although it fires correctly.

[jackssmirkingrevenge]

It looks delightfully post-apocalyptic, and it works! Are you planning a magazine feed system?

[hectmarr]

It looks delightfully post-apocalyptic, and it works! Are you planning a magazine feed system?

Yes, I have fallen in love with this improvised rejunte of workshop elements, post apocalyptic! 8) Now it looks black and has a grip on the front. I am making a short weapon with the same system, with recycled elements, something similar to this but smaller, for fun.
Regarding what you ask me, I told you that this was a valve test integrated into the burned gas cleaning system. This will be the one I will use to make a semi-automatic hybrid, and in small hybrids of air loading by pumping, with the same system that I have tested, the one in the previous videos, the post of semiautomatic, and with the other systems that are already tested. This was the idea, but I had to prove if this part worked correctly. It is for this reason that I did not attach the other systems. I think it's the last piece of the puzzle that I needed to prove ...
When I have something else, I'll put it right here. Greetings Jack!

[hectmarr]

I was thinking about not including in the weapon itself, all systems, I mean the gas loading, valves, compressed air etc. I'm considering leaving this aside, and taking everything to the "firing head" that is what I have in my hands, to simplify the construction, at least as a palliative idea. In the future, when everything is tested, I will have to miniaturize the components to include them within the weapon itself. Equally, the accessories are not very bulky, so I would have them installed in my waist, to be able to move and shoot. I have not decided yet, it's just an idea to simplify
My home compressor can only raise the pressure to 8 bar, which is where the red scale starts on the pressure gauge, and it is where the pressure switch cuts the current and stops the motor. So I'm cleaning a small gas jug of 1 kg, which has an internal volume of about 2 liters, to use with compressed air to power the system. Is what there is and my next purchase, without doubts, will be an air pump pcp weapons to be able to fill deposits to much more pressure.

[Air2theBrain]

Looks great Hectmarr..and that sound

[hectmarr]

Looks great Hectmarr..and that sound

Yes, it's quite noisy, I'm just trying to find information to make a simple silencer. I'm bothered by loud noises ...
Here I have a picture of the "invention" painted to make the appearance more aesthetic. Thanks Air2theBrain

[Air2theBrain]

Ooh lovely i love the black..looks more gangster now. 8) 8)

[farcticox1]

Reminds me of MP40, and that's a good thing

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[hectmarr]

Reminds me of MP40, and that's a good thing

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You're right. It was very similar.
I was forced to paint it because my friends say it's Chucky's weapon! :bounce: