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 72 users online :: 5 registered, 0 hidden and 67 guests


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

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

The Team
Administrators
Global Moderators
global_moderators.png CS

Plans, what do you think? EDIT added pictures

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

Plans, what do you think? EDIT added pictures

Unread postAuthor: Jeeperforlife » Tue Mar 11, 2008 8:00 pm

I have layed low for a few weeks wile I have been working and planning my gun. I will build my first hybrid this weekend and I am wondering what you think of the specs.
6" OD 1/8th" wall steel pipe 30" long, welded 1/4" end caps. 2" union.
For now I plan on using it more for testing for the purpose of building others and making loud bangs. Though I am sure it will get a short barrel at some point.
The steel is some I had left over from a old project. and I have aquired most of the pieces. I will be hard mounting it to a old lawn mower trailer on a turret. It will have a built in compressor and mapp gas tank.
The ignition will be a 15,000 volt transformer for neon lights that will make a 1" ark. I will be putting a simple automotive spark plug in it for now.
A couple of questions I have used burnt lakes gas tool to get the legnth of the meter pipe but I assume the given pressures are for propane. Do I need to modify it for Mapp? It will have wireless remote ignition, what is the highest load I should go?
  • 0

Last edited by Jeeperforlife on Sun Mar 30, 2008 12:19 am, edited 1 time in total.
User avatar
Jeeperforlife
Staff Sergeant
Staff Sergeant
 
Posts: 108
Joined: Tue Jan 15, 2008 4:51 pm
Country: United States (us)
Reputation: 0

Unread postAuthor: Fnord » Wed Mar 12, 2008 10:27 am

Unless you plan on a 50 foot barrel, that chamber is overkill. WAAAY overkill.
Something 1/3-1/2 of your barrel volume will give about the same result and be much easier to move/fill.

I wouldn't go for higher mixes when you only have a 1/8 wall thickness. Even then you better test it remotely a bunch before you fire it up close.(high, meaning 6x+. )

A 15kv neon sign transformer can light you up pretty good, if not kill you. Why add another potential risk to the equation when a stungun, piezo, or flash+ignition coil will give the same result? (If you're only using one spark gap)
  • 0

Image
User avatar
Fnord
Major General
Major General
 
Posts: 2244
Joined: Tue Feb 13, 2007 9:20 pm
Location: Pripyat
Reputation: 7

Unread postAuthor: DYI » Wed Mar 12, 2008 10:49 am

I think that, since this is a hybrid, you should do the meter calculations yourself, just to make sure. Remember to take into account gas that will remain in the meter, and the way that more will remain in the meter with every successive injection because of steadily increasing chamber pressures.

Also, I believe that MAPP should be closer to 5% in air, but I don't know the exact number. It contains methylacetylene, propadiene, and propane, for what it's worth, but I don't know the proportions, and there may be other ingredients that aren't mentioned.

If the chamber tube is seamless 304 SS, Barlow's formula would seem to indicate that its failure pressure is ~1300 psi if yield strength is used, and ~3600 psi if ultimate strength is used. 1300 seems to be more likely, but could someone who knows which one to use please tell me?
  • 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: Jeeperforlife » Wed Mar 12, 2008 10:49 am

_Fnord wrote:Unless you plan on a 50 foot barrel, that chamber is overkill. WAAAY overkill.
Something 1/3-1/2 of your barrel volume will give about the same result and be much easier to move/fill.

I wouldn't go for higher mixes when you only have a 1/8 wall thickness. Even then you better test it remotely a bunch before you fire it up close.(high, meaning 6x+. )

A 15kv neon sign transformer can light you up pretty good, if not kill you. Why add another potential risk to the equation when a stungun, piezo, or flash+ignition coil will give the same result? (If you're only using one spark gap)


Like I said before this one is just being made from what I have on hand, more to test different fuels, and I am shure at 5X, no barrel it should rival any M80 in noise. I am not really looking for peak performance, I will be making some smaller ones in the future. (though I did just get a 80 gallon compressor take for free). We carry 10 ft pieces if 2" at work so I will probly pick one up for it.

The neon trasnformer I got a few years ago after a sign change at a old job. I have been shocked by it though not directly always though something else with high resittance. The remote is about 20' range and I never plan on firing it in my line of sight. I will always have something in between it and me.

Edit, Just saw DYI's reply.
Part of the point of this is to test different pressures and mixtures. I think I will start with where Burnt lake says and see if I can get some better answers for Mapp. the chamber is mild steel and and does have a seam. I have it left over from some air tanks I was building for my Jeep.

Thanks for the replys. I still have a lot of learning to do.
  • 0

User avatar
Jeeperforlife
Staff Sergeant
Staff Sergeant
 
Posts: 108
Joined: Tue Jan 15, 2008 4:51 pm
Country: United States (us)
Reputation: 0

Unread postAuthor: Jeeperforlife » Fri Mar 21, 2008 11:19 pm

Got it built and now am working out the bugs. I will finish it up and get pictures this weekend. I fired it a few times at just 2X last monday, quite impressed with the power it seems to have.

Two questions,
I am having trouble with burst disks, I have a 2" union and ground down the side with the ridge that goes out. I have a rubber gasket that keeps it sealed very well. But any Burst disk I use pops out at over 50 PSI, it doesn't burst it just pops out. I am going to try Al. flashing, it is .0092" thick and should be right about what I want, I hope. Any ideas?

A wile back I read about a high preshure compressor-generator that went inline with any compressor that multiplied the pressure of the first compressor. It was self powered and could build up to 2000Psi if I remember right. What was it? I have researched and can't find any thing on it.

Marcus
  • 0

User avatar
Jeeperforlife
Staff Sergeant
Staff Sergeant
 
Posts: 108
Joined: Tue Jan 15, 2008 4:51 pm
Country: United States (us)
Reputation: 0

Unread postAuthor: DYI » Sat Mar 22, 2008 9:06 am

Firstly, how much are you tightening the union? You should be turning the knut as far as it can possibly go with an 18" or larger pipe wrench, while bracing it on something solid with another wrench.

I've seen something similar to what you're talking about on McMaster, called a pressure amplifier. They trade flow for pressure, and range from $400 to about $1500. But considering the chamber material, you really shouldn't be pressurising it before ignition to anything higher than your average compressor can generate.
  • 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: Jeeperforlife » Sat Mar 22, 2008 9:25 am

DYI wrote:Firstly, how much are you tightening the union? You should be turning the knut as far as it can possibly go with an 18" or larger pipe wrench, while bracing it on something solid with another wrench.

I've seen something similar to what you're talking about on McMaster, called a pressure amplifier. They trade flow for pressure, and range from $400 to about $1500. But considering the chamber material, you really shouldn't be pressurising it before ignition to anything higher than your average compressor can generate.


I am tightening the union with a 24" pipe wrench as hard as I can.

The only reason I want the pressure amplifier is to try different burst disk pressures and i want to build a high pressure pneumatic this summer.
  • 0

User avatar
Jeeperforlife
Staff Sergeant
Staff Sergeant
 
Posts: 108
Joined: Tue Jan 15, 2008 4:51 pm
Country: United States (us)
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: DYI » Sat Mar 22, 2008 9:34 am

What disk materials are you using? Are they as large as the sealing face of the union? Do you have a picture of the union? Why did you grind down the sealing face?
  • 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: Jeeperforlife » Sat Mar 22, 2008 9:47 pm

DYI wrote:What disk materials are you using? Are they as large as the sealing face of the union? Do you have a picture of the union? Why did you grind down the sealing face?


The burst disks have been aluminum foil and two liter plastic. I ground off the inside sealing surface after reading that when it was ground down and a rubber gasket was added it sealed better. I have been having problems with the burst disk on my pneumatic not sealing so I tried this. I will get pictures of it tomorrow.

Edit I could not get down to the shop to get pictures today. I will get them this weekend. I also hope to get the barrel done and everything painted.
  • 0

User avatar
Jeeperforlife
Staff Sergeant
Staff Sergeant
 
Posts: 108
Joined: Tue Jan 15, 2008 4:51 pm
Country: United States (us)
Reputation: 0

Unread postAuthor: Jeeperforlife » Sun Mar 30, 2008 12:27 am

I got a few pictures tonight. They should be pretty self explanatory. Post up if you have any questions. I need to get the barrel still, it will be 10 foot 2" steel conduit.
This is my first hybrid so don't expect much. A few things I need to do is support the metering chamber, redo the igniter, I'm adding spark plugs top and bottom.
My second one is turning out better.

Image

Image

Image

Image

Image

Image

Image

Image
  • 0

User avatar
Jeeperforlife
Staff Sergeant
Staff Sergeant
 
Posts: 108
Joined: Tue Jan 15, 2008 4:51 pm
Country: United States (us)
Reputation: 0

Unread postAuthor: sniperjosh » Sun Mar 30, 2008 6:09 am

what a beast, gigantic chamber.
  • 0

User avatar
sniperjosh
Specialist
Specialist
 
Posts: 57
Joined: Tue Oct 11, 2005 5:58 am
Reputation: 0

Unread postAuthor: DYI » Sun Mar 30, 2008 9:18 am

Welding looks a tad messy, but overall pretty good. How thick are the end plates? I'd suggest no less than 1/2" for 6" pipe, as 4" pipe should have caps at least 1/4" thick for 10x, and 6" has twice the cross sectional area. Igniting from the front may not be the best idea though...
  • 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: SpudFarm » Sun Mar 30, 2008 1:59 pm

why not ignite in the front DYI?
the shot is not fired until the disk goes...

500 posts :)
  • 0

"Made in France"
- A spud gun insurance.
User avatar
SpudFarm
Donating Member
Donating Member
 
Posts: 2563
Joined: Sat Nov 04, 2006 9:39 am
Location: Norway Trondheim area
Reputation: 0

Unread postAuthor: DYI » Sun Mar 30, 2008 3:14 pm

I just reread his post, and it said that he was adding more ignition points. So there's no problems, other than the rather thin pipe.

This forum seems to be getting a lot of monster hybrid projects, doesn't it spudfarm? :wink:
  • 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: Jeeperforlife » Sun Mar 30, 2008 11:25 pm

DYI wrote:This forum seems to be getting a lot of monster hybrid projects, doesn't it spudfarm? :wink:


Inside joke?

Thanks for the replys. the welds and spatter have not seen the grinder yet. I will paint the chamber. I am going to switch over to duel ignition once I get it on the tripod. the end caps are just 1/4 inch but I don't plan on taking it over 6X. I have rethought the barrel and am going to try to find a stick of 2.75" exhaust pipe to shoot concrete filled coke cans.
  • 0

User avatar
Jeeperforlife
Staff Sergeant
Staff Sergeant
 
Posts: 108
Joined: Tue Jan 15, 2008 4:51 pm
Country: United States (us)
Reputation: 0

Next

Return to Hybrid Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], Google Adsense [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'