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Two-stage hybrid

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
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Re: Two-stage hybrid

Unread postAuthor: Skywalker » Sat Nov 02, 2019 10:57 am

Interesting concept, me gusta! The trouble with conventional dieseling spring-guns is the variability of the ignition timing due to fuel mix, which can damage the piston and cause unstable muzzle velocity. Having the ignition occur at a fixed compression could help solve those problems. Metering the fuel to get a consistent mixture ratio is also going to help.

Sometimes the ignition may fail. Make sure that the piston doesn't damage the spark gap by hitting it. I'd suggest having the spark gap contacts be in the wall of the cylinder, rather than on the face. Make sure they are flush with the wall, and have the o-ring gland in the piston set back from the piston face so that the o-ring doesn't get shredded by passing over the contact. This would also prevent the contacts from being shorted out by gunk smeared over the contact insulators by the o-ring.

You'll need a high voltage capacitor & charging supply, rather than a BBQ igniter.
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Re: Two-stage hybrid

Unread postAuthor: jackssmirkingrevenge » Mon Nov 04, 2019 5:50 am

Worth mentioning the Barracuda EL-54 rifle that was deliberately designed to diesel by injecting ether into the chamber:

Image

Apparently it didn't last in the real world though:

The EL54 was an early attempt (1954-1981) at achieving magnum power in a spring-piston air rifle. It is an HW 35 with an ether injector attached on the right side of the compression chamber tube. A medical ether ampule was inserted into the device and crushed. Each time the rifle was cocked and loaded, a shot of ether was injected into the compression chamber, where the heat of compression ignited it, raising gas pressure in the compression chamber.

The device was hell on pellets, blowing out their heads and leaving the bodies trapped in the barrel, so round balls were the only recommended ammo. It also blew the leather seals out of the early guns. It was very difficult to get medical ether ampules in the U.S., so the system was never popular. Most of the guns seen today are in new or nearly new condition.
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: Two-stage hybrid

Unread postAuthor: hectmarr » Mon Nov 04, 2019 9:42 am

Sometimes the ignition may fail. Make sure that the piston doesn't damage the spark gap by hitting it. I'd suggest having the spark gap contacts be in the wall of the cylinder, rather than on the face. Make sure they are flush with the wall, and have the o-ring gland in the piston set back from the piston face so that the o-ring doesn't get shredded by passing over the contact. This would also prevent the contacts from being shorted out by gunk smeared over the contact insulators by the o-ring.

My thinking tries to regulate the moment of the explosion in the shooting chamber. It has a screw, as in the drawing), which can move forward or backward the moment the spark jumps depending on the position of the piston. When the spark jumps later, more compression, when it jumps further back, less compression. I have the idea that the "bridge" that approaches the contacos, (in blue), should support the contact, perhaps using an o'ring to dampen the impact a bit. A matter of testing and drawing conclusions based on the facts. If I have the ignition contacts laterally, I would lose the possibility of being able to regulate all this, apart from that it is much more complicated, because it is necessary to weld the electrode housing to the tube.
Worth mentioning the Barracuda EL-54 rifle that was deliberately designed to diesel by injecting ether into the chamber:

Wow, excellent weapon, very interesting! I had never heard of her. :roll:
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