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 67 users online :: 4 registered, 0 hidden and 63 guests


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

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

The Team
Administrators
Global Moderators
global_moderators.png CS

I need somebody's facts

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

I need somebody's facts

Unread postAuthor: miskaman » Sat Apr 12, 2008 7:46 pm

My dad believes that if I use propane or MAPP gas in a hybrid or even a simple combustion (PVC or steel or aluminum), and ignite it, the whole gun will explode into tiny pieces. Even if I use the reccomended amount of fuel for my size of cannon.

Anyone care to give evidence that he is wrong?
  • 0


miskaman
Sergeant
Sergeant
 
Posts: 82
Joined: Wed Apr 12, 2006 5:27 pm
Reputation: 0

Unread postAuthor: benstern » Sat Apr 12, 2008 8:04 pm

The maximum combustion pressure of Propane is around 150 psi. It rarely ever gets to this in normal combustions. Pressure rated PVC will work with this as well a half inch thick walled steel pipe used for air conditioning and heating ducts.

This is just another case of parent ignorance, it happens somewhat often.
  • 0

User avatar
benstern
Donating Member
Donating Member
 
Posts: 909
Joined: Wed Sep 21, 2005 8:24 pm
Reputation: 0

Unread postAuthor: mopherman » Sat Apr 12, 2008 8:05 pm

simply tell him that the average pressure of a 1x propane ignition is close to 90psi for a very short period of time. Then tell him that pressure rated pvc is more than enough to handle that pressure and temperature. Its written right on the side of the pipe.
  • 0

searching for a modern day savior from another place,inclined toward charity,everyone's begging for an answer,without regard to validity,the searching never ends,it goes on and on for eternity
-Bad religion
User avatar
mopherman
Brigadier General
Brigadier General
 
Posts: 788
Joined: Sat Feb 03, 2007 8:20 pm
Reputation: 0

Unread postAuthor: miskaman » Sat Apr 12, 2008 9:07 pm

Thanks, I'll see what he has to say to that.
  • 0


miskaman
Sergeant
Sergeant
 
Posts: 82
Joined: Wed Apr 12, 2006 5:27 pm
Reputation: 0

Unread postAuthor: Blitz » Sat Apr 12, 2008 9:10 pm

Plus, it's only exposed to that kind of pressure for milliseconds of time.
  • 0

User avatar
Blitz
Colonel
Colonel
 
Posts: 621
Joined: Sat Apr 07, 2007 1:48 am
Location: West Chicago, IL
Reputation: 0

Unread postAuthor: potatoflinger » Sat Apr 12, 2008 9:12 pm

My parents are the same way, they won't let me build a combustion gun, but they will let me build pneumatic cannons. (which I think are more fun anyway).

My advice is that you just build a pneumatic, as long as you use pressure rated parts.
  • 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: miskaman » Sat Apr 12, 2008 9:20 pm

potatoflinger wrote:My parents are the same way, they won't let me build a combustion gun, but they will let me build pneumatic cannons. (which I think are more fun anyway).

My advice is that you just build a pneumatic, as long as you use pressure rated parts.


Eh, combustions are cooler I think. And the weird thing is, I can build a combustion made to be used with hairspray, just not propane or MAPP.
  • 0


miskaman
Sergeant
Sergeant
 
Posts: 82
Joined: Wed Apr 12, 2006 5:27 pm
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: starman » Sat Apr 12, 2008 9:43 pm

Just tell your parents that there are real live parents (ie. me) that design and build combustion cannons....and lets his children shoot them. Truthfully, if it were that volatile, Spudfiles (and Spudtech before it) could not exist openly.

Seriously, if he would like to email or telephone, I would be glad to talk. Just PM me and lemme know....

You could use D_Hall's HGDT tool to mock up a gun and show him the pressures in the chamber and barrel involved. Download it here and run it:

http://thehalls-in-bfe.com/HGDT/

1x and even 2x guns stay well within the pressure limits of even sched 40 PVC.
  • 0

User avatar
starman
Donating Moderator
Donating Moderator
 
Posts: 3041
Joined: Wed Dec 12, 2007 12:45 am
Location: Simpsonville, SC
Reputation: 0

Unread postAuthor: DYI » Sat Apr 12, 2008 10:25 pm

Ask him if the engine block of his car explodes into tiny pieces when he starts it up; it's essentially a full auto, 8x hybrid.

Or you could always show him one of the hybrids on here, or _Fnord's test of SCH 40 2" steel at 11x hybrid mixes, which still couldn't come close to breaking the pipe.

Or, if he's a scientific type (which he probably isn't, if he believes what he says), you can always get into the low density and bond strengths of propane compared to solid explosives, the studies that show its DDT runup distance to be over 10 metres in ideal conditions, and the fact that, since it contains no oxidiser, it's impossible to overload fuel.
  • 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: Velocity » Sat Apr 12, 2008 11:21 pm

Blitz wrote:Plus, it's only exposed to that kind of pressure for milliseconds of time.


As compared to milliseconds of what :lol: ?
  • 0

User avatar
Velocity
Brigadier General
Brigadier General
 
Posts: 1039
Joined: Tue Feb 07, 2006 5:42 pm
Reputation: 0

Unread postAuthor: Blitz » Sat Apr 12, 2008 11:25 pm

Well, since you called me on it, you tell me. :)
  • 0

User avatar
Blitz
Colonel
Colonel
 
Posts: 621
Joined: Sat Apr 07, 2007 1:48 am
Location: West Chicago, IL
Reputation: 0

Unread postAuthor: trae08 » Sat Apr 12, 2008 11:34 pm

just show him a you tube video of someone using mapp or propane in a cannon....
  • 0

Marvin the Martian: Where's the kaboom? There was supposed to be an earth-shattering kaboom!

Marvin the Martian: The Earth? Oh, the Earth will be gone in just a few seconds.

PCGUY wrote:Congrats, your the first donating member I have had to ban.
User avatar
trae08
Donating Member
Donating Member
 
Posts: 520
Joined: Sun Jul 09, 2006 2:14 pm
Location: florida
Reputation: 0

Unread postAuthor: psycix » Sun Apr 13, 2008 6:08 am

Parents with a lack of knowledge mots of the time think that its an "explosion" and thus its dangerous.
But its isnt a explosion, its a deflagration, just a normal buring process of the gas.

People are scared of fire and most of the time think that pneumatics wich use air are undangerous.
(though WE know pneumatics can be more powerful then combustions :D )
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Unread postAuthor: sniper hero » Sun Apr 13, 2008 6:22 am

I can't add something an the other forum members
but "the recomended amount of fuel"
to little fuel will give no ignition or low power shot and too much won't ignite at all because there is no oxygen.
  • 0

proud member of dutch spud clan
coming: semi auto pellet sniper:D
User avatar
sniper hero
Captain
Captain
 
Posts: 332
Joined: Fri Mar 07, 2008 3:12 pm
Reputation: 0

Unread postAuthor: SpudFarm » Sun Apr 13, 2008 8:37 am

[youtube]http://youtube.com/watch?v=zMVwJnGw3fY[/youtube]

this is a pressure test of a 5" steel pipe with 7mm thick walls.. everyone thought it would be quite unsafe at 10x mixes.. that was because of it's large areal and "thin" walls.

Larda proved them wrong with this 2610psi test..

2610psi are equal to a 24x propane mix..

Larda put it this way when i had doubts.. "a plastic soda bottle has 0.34mm thick plastic walls and can take 150 psi" that made me thinking..

i am a metric guy just search "....mm in inch" om google
  • 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

Next

Return to Hybrid Cannon Discussion

Who is online

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

Reputation System ©'