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overly large 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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overly large Hybrid?

Unread postAuthor: striker » Sat Jan 24, 2009 12:12 am

Hi guys and girls

This is my first post on here so please be nice.lol

Anyhow I have been contemplating a hybrid build for some time and for the record it will be built by an engineer.
The problem I have it is proberly one of the bigger hybrids and although I have been using HGDT for help Im still unsure on a few things.
Its been designed for a 4:1 ratio and the chamber is 30 litres.

[Using HGDT it predicts better the higher C:B ratio for the projectile weight (long for bore) I will be firing]

I am only using two ingition points at this stage but the thing I deffinaty dont want is a detonation at 8x and above
Should I use more igniters?
Is there any problems I should research before going above 30 litre in chamber size.

Thats all I can think of for now.
should be an interesting thead

regards
striker
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Unread postAuthor: CasinoVanart » Sat Jan 24, 2009 3:28 am

Hey Striker, a thirty litre Hybrid would be interesting indeed and also the largest hybrid i have heard about (apart from one particular monster that is highly top secret). C:B ratio of 4:1 would be highly wastefull in a hybrid, something like 0.5:1 is more realistic.

Have you had the chance to draw up any plans or are you just going to make it as you go along (thats what i do)?

Chamber shape and materials used would be of great benefit to us if you want some real advice, an actual plan/drawing would be the best thing if you want to pick the brains of all the hybrid nerds here.

All in all im getting drunk and love hybrids.......
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Unread postAuthor: daccel » Sat Jan 24, 2009 3:30 am

What dimensions are you thinking? 30 litres could come in many shapes. It would be cheaper to do a longer narrower chamber, but that also increases the risk of ddt I from what I understand.

Edit: beaten to it - yes, more specifics will increase the response you get. As an aside, also drinking and loving hybrids :D.
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Unread postAuthor: CasinoVanart » Sat Jan 24, 2009 3:36 am

Don't worry about ddt too much, the run up distance required is massive and by all accounts even people trying to achieve it have a hard time doing so. The most important aspect is finding a vessel that can withstand the spike pressures involved.

The hardest part for most people is fueling and getting the burst disc to seal (unless you are making a piston hybrid).
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Unread postAuthor: striker » Sat Jan 24, 2009 3:38 am

Hi guys

ok Casinovanart
Iwill try and get sum of my work online. all my designs are done by hand apart from HGDT.

Daccel
well the dimentions arent finalized yet be cause im haveing trouble geting a 2500PSI capable tank for safety.
Um ar i wasnt going to tell you this but the chamber size i listed is only about one third of what my original deisign calls for.

striker

Ps im not mad just like to design the biggest and the best
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Unread postAuthor: CasinoVanart » Sat Jan 24, 2009 3:44 am

I understand about the mad part!! 2500psi in a chamber that large is going to be a challange. What mixes are you planning? 2500psi is like a 50x mix...
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Unread postAuthor: starman » Sat Jan 24, 2009 3:46 am

First off, a 30 liter hybrid chamber is a ridiculous thing....in a good way...potentially... :wink: It will also be an artillery sized piece so you need to think about mounting and transporting it as much as the cannon itself.

A 4:1 hybrid will be rather wasteful but on an absolute scale will be more powerful than a 3:1 or 2:1 or anything less actually. Bigger chambers will always produce more power than a smaller one. The efficiency of that chamber/barrel combo is another issue.

I would try to use as many ignition points as you can. Unfortunately, the higher X you go, the harder it is for a spark to jump the gaps. You have to narrow them way down. A 2 gap ignition is doable...mount them equidistant in the chamber...not close together.

What kind of ammo are you planning for this beast.
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Unread postAuthor: striker » Sat Jan 24, 2009 3:55 am

CV:
IN NO WAY am I planning to get that high in PSI ratings yet.I plan on 12x mixs and roughly 1000psi to any pressure spikes.

Starman:
um Im not planning on a 30 litre chamber I was hoping to find a 100 litre chamber.
as for projectiles thats a secret for now.
But I can tell you the weight, try 1500grams at just shy of 500m/s

striker
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Unread postAuthor: starman » Sat Jan 24, 2009 4:26 am

Have you had any experience with otherwise real world spud guns? Combustion...Pneumatics...? I think it would be prudent to get some hands-on experience on a scaled down basis. It's difficult enough to get things right on an advanced combustion or a more standard sized hybrid.

I'm not necessarily doubting your capability to do this...we don't know you very well yet. I just want to make sure you grasp what it is you're really contemplating here.
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Unread postAuthor: striker » Sat Jan 24, 2009 4:41 am

I have made pnuematic cannons in the past.Fairly large ones utilizing 200 litre drums and capable of firing baked bean cans 100/150m. but as they had a few design faults I what to make this one
as safe as possible.
Im trying to work through it all and even if I dont manage to build it well it certainly has been fun designing it.
I certainly could just go out and build it but as I like some coflicting arguments and opinions I put the idea up here first.

regards
striker
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Unread postAuthor: starman » Sat Jan 24, 2009 4:50 am

I would then suggest you build yourself a standard 1X advanced combustion first. Combustions are different enough from pneumatics to make it worth while. Many of your hybrid answers will come naturally to you then. Also, take a good long look through the hybrid showcase. This thing, FEAR, is the only hybrid I know of that comes close to the scale of things you are talking about.

This project is also going to cost you some fairly serious dough and time to build right AND safely. I wish you the all the best in the endeavor.
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Last edited by starman on Sat Jan 24, 2009 5:15 am, edited 3 times in total.
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Unread postAuthor: striker » Sat Jan 24, 2009 5:13 am

that is some good advice and I proberly will build a down scaled model before attemping project B.A.M.F. It will take some dough and and more importantly time but its somthing I hope to achive. Once I finally get a set design and specs anyway.

I had a basic image of wat I wanted to do long before I found this site but the writeups have certainly helped me learn possible problems and how to over come them.

bigger better faster stronger

regards

striker
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Unread postAuthor: D_Hall » Sat Jan 24, 2009 11:41 pm

Yeah, a 30 L hybrid would be a beast and Damned Tough to store in the average garage.

Besides the very large but low X hybrid that I'm currently contructing, there is a... Oh, I'm going to guess and say... roughly 30 L hybrid at the office. The gun is rated to 3,000 psi, but I'm not sure what they run it at (I've seen the gun, but I've never used it myself). So we're talking about roughly the same size here, right?

For perspective, the barrel on that gun is 6" bore and probably 25' long. Overall, the gun probably weighs in at about 5,000 pounds.
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Unread postAuthor: striker » Sun Jan 25, 2009 3:07 am

Well I am designing it to be take down and trailer portable.
The barrel will be similar to the one mentioned in the post above.
I am Guess/Esimating the recoil will be severe so I will have to incorporate a muzzle brake.
I had designed a rail system for the recoil but to get the best out of it it would have to be quite large.

I have just found a readily avalible type of vessel that Im doing a little research on to verify pressure capability.
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Unread postAuthor: Gippeto » Sun Jan 25, 2009 1:03 pm

striker wrote:The barrel will be similar to the one mentioned in the post above.
I am Guess/Esimating the recoil will be severe


That is something of an understatement.

This will be an expensive undertaking by private individual standards, dare I ask "Whom is funding this project?"
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