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Overly Ambitious, but doable.

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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Overly Ambitious, but doable.

Unread postAuthor: individual » Fri Mar 14, 2014 8:59 am

Hey there :)

I've made quiet a few cannons back when I was younger, and I never knew there was a community like this. Such a pity :(
Image
Image(that one hurt)
Image

These were about 6 years ago now. haven't made one since.

Anyway, since I've been browsing these forums, I was looking for a challenge, and I came accross two.

The first, mobile chernobyl's 10XGB Hybrid.
hybrid-cannon-database/topic23523-60.html#wrap
Brilliant Design and very very nice for a first hybrid. Also have to commend him on the welding.

And the second, of course, the infamous Larda Hybrid
hybrid-cannon-database/topic15524.html
Fantastic performance, great machining, and scarily powerful for a home-made "spud gun" :P



No doubt some of you on here know of Utron's Combustion Light Gas Gun project.
The 16/45 and their pinnacle, the 155mm combustion light gas gun, Capable of propelling 18.5kg projectiles, 4.2 kilometers per second.

My inspiration came (Like Mobile Chernobly, presumptively) from Utron's experimental cannons.

This is my first Design. I have another, stronger, bigger and more complicated design, however it inst completed yet. Figuring out an auto loading mechanism that can mate the barrel and chamber back to resist up to 90,000 PSI is......interesting.

This one is designed to reach mach 4.
Untitled5.png

Untitled4.png


In short, I want to (attempt to) break Larda's record :)

I can't say when this will be completed, or if i really have bitten off more than I can chew this time.
But I'll update this as it goes :)
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Re: Overly Ambitious, but doable.

Unread postAuthor: jackssmirkingrevenge » Sat Mar 15, 2014 7:47 am

individual wrote:(that one hurt)


Hopefully just your pride, it's a spudder's rite of passage ;)

Also, you included not one but two socks in the photo - the spudfiles spirit was inside you all along!

In short, I want to (attempt to) break Larda's record :)


Big shoes to fill, but if one is so inclined and has the mechanical and financial resources... go for it!
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Re: Overly Ambitious, but doable.

Unread postAuthor: individual » Sat Mar 15, 2014 8:43 am

jackssmirkingrevenge wrote:
individual wrote:(that one hurt)


Hopefully just your pride, it's a spudder's rite of passage ;)


Unfortunately not lol.
Was at my friends place when it happened. We atomized a few plants that made us very hungry :roll: , and it seemed like a good idea to put some oxygen and butane into this old, 100+ shots fired PVC spud gun.......
sitting the cannon vertical on the edge of a trampoline while I stood and filled it with a kitchen towel of all things (no oranges or spuds)
I pushed the button,
cannon exploded
i got knocked off my feet
oxygen tank ended up in the front yard, some 30 meters away over the roof
hole in trampoline
and one partially (but only temporarily) deaf Mitch.
Couldn't hear out of one ear for a good few days.

Needless to say, I developed remote ignition after that day.
http://www.youtube.com/watch?v=RVzUe73NoTk

And never atomized hunger inducing plants again.

jackssmirkingrevenge wrote:
individual wrote:In short, I want to (attempt to) break Larda's record :)


Big shoes to fill, but if one is so inclined and has the mechanical and financial resources... go for it!


Mechanical yes, financial no lol.

Fitter and turner (mechanical, yes) Apprentice (financial, no)

But, all good things come to those who wait :)
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Re: Overly Ambitious, but doable.

Unread postAuthor: individual » Sat Mar 15, 2014 8:50 am

jackssmirkingrevenge wrote:
individual wrote:(that one hurt)


Hopefully just your pride, it's a spudder's rite of passage ;)


As for pride, this was the last highlight i got on video of my spudgunning days :P
http://www.youtube.com/watch?v=eVn9hANBn2o
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Re: Overly Ambitious, but doable.

Unread postAuthor: Ragnarok » Sat Mar 15, 2014 9:29 am

individual wrote:In short, I want to (attempt to) break Larda's record :)

Well, that depends on what you think Larda's record is...

A higher mix number is possible, but with propane 200x is starting to reach partial pressures that would result in liquefied propane in the chamber and the need to ignite a lean mix. That might be achievable, but a search for another fuel may be a smarter move.

As far as a velocity record though, I think he only holds the forum's record for hybrids, as I think the overall record is currently in the hands of DYI's ETAV2.1, which was starting to approach the hypervelocity region of around 3000 m/s (approximately Mach 9).

Still, I'm all behind seeing pretty machining projects!
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Does that thing kinda look like a big cat to you?
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Re: Overly Ambitious, but doable.

Unread postAuthor: individual » Sat Mar 15, 2014 10:24 am

Ragnarok wrote:
individual wrote:In short, I want to (attempt to) break Larda's record :)

Well, that depends on what you think Larda's record is...

A higher mix number is possible, but with propane 200x is starting to reach partial pressures that would result in liquefied propane in the chamber and the need to ignite a lean mix. That might be achievable, but a search for another fuel may be a smarter move.

As far as a velocity record though, I think he only holds the forum's record for hybrids, as I think the overall record is currently in the hands of DYI's ETAV2.1, which was starting to approach the hypervelocity region of around 3000 m/s (approximately Mach 9).

Still, I'm all behind seeing pretty machining projects!


Ah, yes I forgot to consider that. Using hydrogen, which won't liquify until it reaches 800 BAR would be more efficient, but air liquifies at about 250 anyway.
The next step would be to use liquid but that's another ball game entirely, multistage compressors/accumulators/cryogenic temperature stable steel etc.

That ETG cannon is impressive, however I'm doubting the maths involved. (haven't done the calculations but something doesn't seem right) a 5mm bearing should be able to penetrate 9mm steel going 6000-9000fps. Perhaps it's just some wasted energy from the difference in weight from an airsoft to a bearing round.
That been said, it's still very impressive and scary for such a small package :shock: and it looks like for a record I'll have to fire a .5gram projectile at 3000m/s :) this is gonna get interesting fast :D
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Re: Overly Ambitious, but doable.

Unread postAuthor: Ragnarok » Sat Mar 15, 2014 12:36 pm

individual wrote:Ah, yes I forgot to consider that. Using hydrogen, which won't liquify until it reaches 800 BAR would be more efficient, but air liquifies at about 250 anyway.

Nah, that's well into the supercritical region for air:
MSP30111cbf319ea4f669bg000030fdh91ib0e10310.gif
MSP30111cbf319ea4f669bg000030fdh91ib0e10310.gif (6.97 KiB) Viewed 966 times

One possibility I did consider a long time ago was a H2/O2/He mix. While the helium wouldn't directly contribute to the combustion energy, a certain percentage of the mix being Helium could improve the end results.

GasEq predicts a very similar end pressure for the combustion of a mix of 2H2: O2 : 3He as it does for 2H2 : O2 , even for the same starting pressure and volume (and thus only half the fuel), but it also reduces the density of the propellant by about a third. And, as a general rule, the lighter the propellant gas, the more efficient it is.

I'm not sure if Utron do or don't do this (and why they do or don't), but it's potentially worth an experiment somewhere down the line.

a 5mm bearing should be able to penetrate 9mm steel going 6000-9000fps.

I doubt the bearing was going as fast as the airsoft BB. It's about four times as heavy, so odds are it was going about half as fast - it may not have been all that much more spectacular in terms of velocity than a fast rifle bullet like the .223 Rem or .220 Swift, but it would have been lumbered with the disadvantage of being about an order of magnitude less massive.

Dependent on the type of steel, you wouldn't necessarily expect to pierce 3/8" steel with a .220 or .223, so a lighter projectile not achieving it isn't too great a surprise.
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Re: Overly Ambitious, but doable.

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Re: Overly Ambitious, but doable.

Unread postAuthor: Brian the brain » Sun Mar 16, 2014 3:21 am

As can be seen in the first picture: You've already decapitated yourself with a lightsabre once...
:D
So... be careful!
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Re: Overly Ambitious, but doable.

Unread postAuthor: jackssmirkingrevenge » Sun Mar 16, 2014 5:00 am

Brian the brain wrote:As can be seen in the first picture: You've already decapitated yourself with a lightsabre once...
:D
So... be careful!


hehehehe!
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Re: Overly Ambitious, but doable.

Unread postAuthor: individual » Wed Mar 19, 2014 3:52 am

Brian the brain wrote:As can be seen in the first picture: You've already decapitated yourself with a lightsabre once...
:D
So... be careful!


haha, yep, that was a good day :)

Haven't done much more on this yet, havent had the time :/ have figured out the fuel loading though, so that's sorted.
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