Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 63 users online :: 2 registered, 0 hidden and 61 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

Registered users: Bing [Bot], Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Detonation gun

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.
Sponsored 
  • Author
    Message

Detonation gun

Unread postAuthor: DYI » Sat Nov 24, 2007 8:27 pm

Just an interesting idea that I have had for a while, but never really posted:

I've heard of high explosive detonations propelling objects at amazingly high speeds, and was wondering if I could replicate something like that. Now, any monkey can fill a steel tube with flash powder, stuff in a projectile, ignite the powder, and get torn in half by a hail of supersonic shrapnel. However, replicating this with only gases, and without the horrible gruesome death part, would be a real challenge. The idea is that the supersonic detonation wave can propel lightweight objects at extremely high velocities. I think I could achieve this with a pressurised mix of O2/H2 in a long, thin chamber, ignited from the rear. I am considering building something like this, but I would first like some advice from the resident genii of Spudfiles to see if it is a viable design.

Questions:
1. I would likely use 2024 aluminum for the chamber, about 1/2" ID, 2"OD, and 36" long. Would this setup be capable of withstanding repeated detonations?
2. Would stoichiometric O2/H2 pressurised to ~30 psi preignition be very likely to detonate in the aforementioned setup?
3. Would a detonation of this mix have a decent chance of propelling a <1 gram projectile down a small diameter barrel to hypersonic speeds? I'd be aiming for >Mach 3 ( what I can't do with helium powered pneumatics).

Useful answers or speculations on the above questions would be appreciated. I would obviously include shrapnel shielding and (very) remote ignition on the design if I were to build it. Comments made in reference to how I will be blown to small meaty chunks when I set this thing off are hereby limited to 5 per page.
  • 0

Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
User avatar
DYI
Lieutenant General
Lieutenant General
 
Posts: 2861
Joined: Sat Jul 07, 2007 8:18 pm
Location: The People's Republic of Canuckistan
Country: Turks and Caicos Islands (tc)
Reputation: 9

Unread postAuthor: potatoflinger » Sat Nov 24, 2007 9:13 pm

The setup MAY be able to handle repeated detonations, but how are you planning on sealing one end of the pipe?
  • 0

It's hard to soar with eagles when you're working with turkeys.
User avatar
potatoflinger
Brigadier General
Brigadier General
 
Posts: 1136
Joined: Thu Nov 02, 2006 3:26 pm
Location: Maryland
Reputation: 1

Unread postAuthor: wannabie » Sat Nov 24, 2007 9:16 pm

Sounds... interestingly suicidal... but if you can get it to work WITH OUT dieing. you would be a spudgunning god in my books. * drools at hypersonic speed *
  • 0

In epoxy we trust.
User avatar
wannabie
Captain
Captain
 
Posts: 304
Joined: Sun Apr 15, 2007 11:44 pm
Location: Australia
Reputation: 0

Unread postAuthor: frankrede » Sat Nov 24, 2007 9:43 pm

Can you weld aluminum?
Its the easiest welding I have done(using a wirefeed)
  • 0

Current project: Afghanistan deployment
User avatar
frankrede
Lieutenant General
Lieutenant General
 
Posts: 3220
Joined: Thu Jul 20, 2006 9:47 pm
Reputation: 0

Unread postAuthor: boilingleadbath » Sat Nov 24, 2007 9:49 pm

ISP of H2-LOX rocket engeins is 530 seconds, IIRC.

... so that sets an absolute upper limit on your attempts, based on the highest velocity one can get H2-O2 exaust to go, of about mach 15.

Other than that, yeah, sounds safe... actually way over built. I've seen research papers on detonation set up DDT scenarios in <i>polycarbonate</i> tubes with ID/OD ratios larger than your gun.
  • 0

User avatar
boilingleadbath
Moderator
Moderator
 
Posts: 1642
Joined: Sat Mar 12, 2005 10:35 pm
Location: Pennsylvania, USA
Reputation: 0

Unread postAuthor: sandman » Sat Nov 24, 2007 9:50 pm

well, first off hypersonic is > Mach 5 not Mach 3

also did you type the pipe right? according to you it would be 1.5 inches think, where do you plan on getting something like that?

but i have wondered about H2/O2 pressurization.

for safety i think you should electrolyze water inside the chamber then use the same electrodes for ignition to reduce the amount of things going into the chamber, also this makes the mix perfectly stoichiometric.

With something this dangerous i would use a wired remote detonator.
  • 0


sandman
Colonel
Colonel
 
Posts: 672
Joined: Thu Mar 15, 2007 6:59 pm
Reputation: 0

Unread postAuthor: windshrike » Sat Nov 24, 2007 9:53 pm

Just so you know, hypersonic- while literally greater than Mach one in it's etymology- should be more than Mach 5.
  • 0

User avatar
windshrike
Sergeant Major
Sergeant Major
 
Posts: 178
Joined: Thu Jun 28, 2007 4:23 pm
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: POLAND_SPUD » Sat Nov 24, 2007 9:55 pm

an O2 and H2 mix is likely to ignite/explode itself as far as i know...
  • 0

User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Unread postAuthor: Novacastrian » Sat Nov 24, 2007 9:59 pm

POLAND_SPUD wrote:an O2 and H2 mix is likely to ignite/explode itself as far as i know...


That would be the entire point of this experiment Mr spud :P
  • 0

America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Unread postAuthor: DYI » Sat Nov 24, 2007 10:00 pm

Well, the chamber would be machined from a solid rod, so the back would be closed already. The front would be threaded, and then have a high pressure brass bushing going to a 3000 psi aluminum union. After that, a short barrel, probably 1/4 or 1/8". With the threads, if (read "when") this thing explodes into its individual components, I may be able to salvage some of the rather expensive bits (like the 3000 psi aluminum union which costs ~$75 :shock: )

This may be a project for next summer. I need to be far away from any civilization when I try this, so my back yard (my only firing range in the winter) is out.

Any ideas for a homemade sparkplug that won't get torn out on the first shot?

EDIT: wow, lots more posts. I was hoping for hypersonic, but at least Mach 3. Mach 15 is an upper limit that I doubt I will ever have to worry about though. If you think that the chamber is really overbuilt, I could always increase the ID to 3/4 or 1", making it easier to work the electrodes. Electrolysing water inside the chamber is an interesting idea. I could simply continue until it autoignites, or failing that, use a second set of electrodes for ignition. I could first use the hole for the ignition electrodes to measure the rate of pressure increase from the electrolysis, and use that as a basis for when to ignite the mix ( because it would destroy one gauge every shot, and that would get expensive).
  • 0

Last edited by DYI on Sat Nov 24, 2007 10:07 pm, edited 1 time in total.
Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
User avatar
DYI
Lieutenant General
Lieutenant General
 
Posts: 2861
Joined: Sat Jul 07, 2007 8:18 pm
Location: The People's Republic of Canuckistan
Country: Turks and Caicos Islands (tc)
Reputation: 9

Unread postAuthor: Novacastrian » Sat Nov 24, 2007 10:02 pm

You should screw the sparkplug in from the inside of the chamber. No way it's going to blow out then. That's what i do in my Hybrids.
  • 0

America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Unread postAuthor: POLAND_SPUD » Sat Nov 24, 2007 10:03 pm

i mean he has to put enough H2 and O2 into the chamber but the problem is that once he try to fill his chamber with them there would be an explosion - he doesn't have to ignite it, it would explode instatntly
  • 0

User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Unread postAuthor: Novacastrian » Sat Nov 24, 2007 10:08 pm

No it won't, the Hydrogen Oxygen mix needs some kind of ignition source.
It probably would explode under enough pressure- but the pressure in this vessel would be non-existent before ignition i think. Just need a bleed valve, or a vaccum before you start the electrolisis.

P.S. Heres a pic of the "sparkplug" i use in my hybrid.
http://i182.photobucket.com/albums/x281 ... rid002.jpg
  • 0

America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Unread postAuthor: DYI » Sat Nov 24, 2007 10:09 pm

That is why I would be electrolysing the water in the chamber to start with, rather than pumping it in. And detonations are a whole different animal from what we are used to. They can blow out all sorts of unexpected things, and a 1" ID chamber is too small to screw in sparkplugs from the inside.
  • 0

Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
User avatar
DYI
Lieutenant General
Lieutenant General
 
Posts: 2861
Joined: Sat Jul 07, 2007 8:18 pm
Location: The People's Republic of Canuckistan
Country: Turks and Caicos Islands (tc)
Reputation: 9

Unread postAuthor: windshrike » Sat Nov 24, 2007 10:11 pm

Inject the mix slowly, put enough pressure in at once and you may exceed the energy of activation without any heat or spark.

EDIT: Okay, I just saw DYI's post, disregard the above^^.
  • 0

Last edited by windshrike on Sat Nov 24, 2007 10:12 pm, edited 1 time in total.
User avatar
windshrike
Sergeant Major
Sergeant Major
 
Posts: 178
Joined: Thu Jun 28, 2007 4:23 pm
Reputation: 0

Next

Return to Hybrid Cannon Discussion

Who is online

Registered users: Bing [Bot], Yahoo [Bot]

Reputation System ©'