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3042 Cubic Inch Hybrid WORKS!

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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Unread postAuthor: jackssmirkingrevenge » Mon Oct 31, 2011 12:10 am

POLAND_SPUD wrote:I guess that would make sense... since you're limited to low mixes it would make sense to make the barrel as large as possible...

bigger barrel = greater barrel volume = quieter gun

Plus it doesn't mean you're limited to big heavy and slow ammo only... With saboted ammo you could lob rounds 1.5 miles away
you see JSR I wrote sabots... that's right now you've got to agree with me : D


I agreed with you before I saw the footnote ;)

Also mentioned in the Paris Gun article:

Finally, an intriguing detail emerges when reading Rausenberger’s own account of the early stages of the Paris Gun design process. Earlier, it was remarked that when Rausenberger was trying to decide how to achieve the requisite muzzle velocity, his assistant, Dr von Eberhard, had made a very radical proposal. Simply, von Eberhard speculated that if the unmodified L52.5 35.5cm gun, which fired a conventional shell of 535kgs, were to use a 90kg 21cm shell slotted into a 120kg 35.5cm calibre short cylindrical "carrier", the combination weighing 210kg, a muzzle velocity of 1500m/s was easily attainable. As the assembly left the muzzle of the barrel, aerodynamic drag on the flat-fronted cylinder would rapidly decelerate it, causing drag separation of the slender 21cm shell and allowing it to continue at the same velocity and reach 100km range.

Von Eberhard had essentially invented the sub-calibre discarding-sabot shell. Rausenberger’s objections to it appear odd, in retrospect. First, he decried the light weight of the shell, only 90kgs. Yet the Paris Gun as built fired shells weighing, on average, only around 100kgs. Further, because von Eberhard’s solution offered a gun firing the sabotted ammunition at normal barrel pressures, his 90kg shell could have relatively thin walls and contain around 18kgs of explosive, as opposed to the Paris Guns’ projectiles with their thick walls (to resist the enormous barrel pressures) and consequent light explosive payload of only around 7kgs. Even better, with the guns operating at normal pressures, barrel lives of 800 rounds could have been confidently expected, as opposed to the Paris Guns’ ephemeral barrel lives of around 65 rounds. More justifiably, perhaps, Rausenberger was also unsure about testing such a novel system in the short time available, and criticised the possibility of the discarded sabots falling on German troops.


I really don't know why the Germans didn't go this route with the Vergeltungswaffe 3 using existing big bore guns instead of pissing about with multi-chambered guns that ultimately didn't work.

They were on the right track with the pfeilgeschoss but it was too late by then.

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Unread postAuthor: POLAND_SPUD » Mon Oct 31, 2011 1:35 am

Also mentioned in the Paris Gun article:
yup, I read it

Ze germans like to make awesome overengineered stuff that is totally impractical...


anyway get HGDT and check how much power you could get by doubling the bore
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Unread postAuthor: saefroch » Mon Oct 31, 2011 1:38 pm

Fnord wrote:If you can get a hold of a section of this stuff, you'll have most of the work of making a barrel support done for you already. Even steel antenna towers are fairly light for their size.

Those are usually used to support tomato plants, you can probably find some at a local gardening center. Only problem is they're not hollow, and thinner.
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Unread postAuthor: Fnord » Mon Oct 31, 2011 5:34 pm

Err... where I come from they're used to support TV antennas :lol:

I had some of it once. The steel stuff is pretty sturdy... I used it for a ladder occasionally.
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Unread postAuthor: Dornep » Wed Nov 09, 2011 9:29 pm

I'm still working away on the cannon guys. I have a new gauge isolated by ball valve meow.. So that's fixed. I inspected the original gauge and noticed that the interior face that the numbers are printed on was actually warped from the test shot!

I have plently of stainless steel turnbuckles now for the barrel support.. if that idea works anyway. Still need the cable.

I have two 15' sections of 2" SCH40 for my barrel.. which is extremely heavy! The cannon is lighter then a feather compared to the barrel! So a total barrel length of 30' meow. Both 15' sections are threaded on one end and I still need to thread the opposite end of each section and get a very strong coupling to attach them...

I have decided to add a second fitting to the chamber which is a 1" bushing that I will weld in - for a homemade spark plug as a backup ignition source.

I have already built the spark plug and camera flash through ignition coil setup which brings me to my next question...

With my current setup, even through the ignition coil my spark/arc will only jump a 1/4" gap in open air.. shouldn't it be more powerful then this? I imagine the resistance of a couple additional atmospheres will only make it worse... I will post pics of my camera flash setup if it will help?
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