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 75 users online :: 5 registered, 0 hidden and 70 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

Fnord's Piston Hybrid 2.0

Built a hybrid cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
Sponsored 

Voice yo opinionz

sexy
49
67%
cool
21
29%
average
1
1%
meh
0
No votes
d4 sux0rz
2
3%
 
Total votes : 73
  • Author
    Message

Unread postAuthor: CpTn_lAw » Fri Jul 20, 2007 1:48 pm

come on guys this is galvanized steel pipe...when hitting it with a hammer, you hurt your hammer, not the pipe.
This is so freakin' amazing. That beats the crap out of my a$$...
i've done one mini hybrid, and curently optimising it, but this is....i mean, come on, this thing , this beast is impressive.
Mach 1 with a 5 gram marble....more energy than a .38 special bullet.

Terrific.
  • 0

"J'mets mes pieds où j'veux, et c'est souvent dans la gueule."
User avatar
CpTn_lAw
Brigadier General
Brigadier General
 
Posts: 987
Joined: Sun Sep 11, 2005 9:10 am
Location: France
Reputation: 0

Unread postAuthor: DYI » Fri Jul 20, 2007 2:11 pm

The reasoning behind not taking a handheld hybrid beyond 4x is that detonation could occur, which would almost surely destroy a galvanised steel launcher, due to the rapid pressure spike. While the material can likely survive the pressure created, it probably wouldn't be able to absorb the sudden impact, and could shatter, which would be very unpleasant (to say the least) for the person holding it.
  • 0

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: CpTn_lAw » Fri Jul 20, 2007 2:14 pm

I know about the DDT, it occurs with propane at 8x mixes....
  • 0

"J'mets mes pieds où j'veux, et c'est souvent dans la gueule."
User avatar
CpTn_lAw
Brigadier General
Brigadier General
 
Posts: 987
Joined: Sun Sep 11, 2005 9:10 am
Location: France
Reputation: 0

Unread postAuthor: SpudBlaster15 » Fri Jul 20, 2007 2:26 pm

Apparently you don't.

DDT can occur at any mix, should sufficient run up distance be given. Increasing the chamber pressure decreases this run up distance, and it is generally accepted that DDT can occur at anything over a 4x mix in a launcher of average size.
  • 0

People should not be afraid of their governments. Governments should be afraid of their people.
User avatar
SpudBlaster15
Major General
Major General
 
Posts: 2385
Joined: Wed Oct 18, 2006 11:12 pm
Location: Canada
Country: Poland (pl)
Reputation: 3

Unread postAuthor: CpTn_lAw » Fri Jul 20, 2007 2:42 pm

a DDT frequently occurs in an air rifle that combusts...
I've seen people take a hybrid over 5x, and have no probs. As you say, it is "accepted" that DDT can occur over 4x, facts tell that a DDT at 5x, or even 6x, is unlikely to happen in normal atmospheric conditions
  • 0

"J'mets mes pieds où j'veux, et c'est souvent dans la gueule."
User avatar
CpTn_lAw
Brigadier General
Brigadier General
 
Posts: 987
Joined: Sun Sep 11, 2005 9:10 am
Location: France
Reputation: 0

Unread postAuthor: SpudBlaster15 » Fri Jul 20, 2007 2:51 pm

I quote jimmy101: (he was referring to you BTW)

do you ever feel like you are "tilting at windmills" on this forum?


4x, 5x, and 6x mixes under 'normal atmospheric conditions'? This makes no sense, as these mixes are far from atmospheric conditions.

What "facts" are you referring to? How about the "fact" that noname managed to get a 6x mix to DDT in a 1/2" steel pipe?
  • 0

People should not be afraid of their governments. Governments should be afraid of their people.
User avatar
SpudBlaster15
Major General
Major General
 
Posts: 2385
Joined: Wed Oct 18, 2006 11:12 pm
Location: Canada
Country: Poland (pl)
Reputation: 3

Unread postAuthor: CpTn_lAw » Fri Jul 20, 2007 2:55 pm

I didn't know that, my bad...But i run my mini hybrid at 6x mixes, and have had no problems at all, pressure peak at 350 psi.
  • 0

"J'mets mes pieds où j'veux, et c'est souvent dans la gueule."
User avatar
CpTn_lAw
Brigadier General
Brigadier General
 
Posts: 987
Joined: Sun Sep 11, 2005 9:10 am
Location: France
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: SpudBlaster15 » Fri Jul 20, 2007 3:01 pm

I am not saying that DDT is guaranteed to occur, as it depends upon chamber geometry more than anything, but I feel it is unsafe to use a hand held hybrid at anything more than a 4x mix.
  • 0

People should not be afraid of their governments. Governments should be afraid of their people.
User avatar
SpudBlaster15
Major General
Major General
 
Posts: 2385
Joined: Wed Oct 18, 2006 11:12 pm
Location: Canada
Country: Poland (pl)
Reputation: 3

Unread postAuthor: CpTn_lAw » Fri Jul 20, 2007 3:10 pm

lol, i'm at 2 meters from my 1/2" chamber mini lol!! and i feel uncomfortable when firing it!! but i think it would handle 7x mixes if there wasn't any DDT.
  • 0

"J'mets mes pieds où j'veux, et c'est souvent dans la gueule."
User avatar
CpTn_lAw
Brigadier General
Brigadier General
 
Posts: 987
Joined: Sun Sep 11, 2005 9:10 am
Location: France
Reputation: 0

Unread postAuthor: Velocity » Fri Jul 20, 2007 5:03 pm

Does anyone actually know the maximum pressure generated in a detonation? It might be enough to break some weak iron pipes, but if you buy high pressure (3000+ PSI working pressure) forged steel pipe and fittings... do you still think that DDT could destroy the pipe?
  • 0

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

Unread postAuthor: PVC Arsenal 17 » Fri Jul 20, 2007 5:10 pm

What exactly is DDT? I know it something like Deflagration to Detonation Transition... but wha exactly is it?
  • 0


PVC Arsenal 17
Major General
Major General
 
Posts: 1762
Joined: Mon Mar 27, 2006 4:18 pm
Location: United States
Reputation: 1

Unread postAuthor: Fnord » Fri Jul 20, 2007 5:18 pm

I'm sorry, I don't have time to answer all these questions today(I'm leaving in 20mins) :(
Maybe you guys can compile them all into a big list or something or send someone up to do an interview lol

Also, does anyone know if galfisk is still around? I haven't seen him on spudfiles, but I think he might like to know of the exsistance of another piston-valved hybrid.

To answer at least 1 question, I don't plan on taking it past 4x, mainly because my chamber has obstructions in it due to the spark gap design, which will help ddt kick in. And I don't plan on taunting the ddt gods:)
  • 0

Last edited by Fnord on Fri Jul 20, 2007 6:13 pm, edited 2 times in total.
Image
User avatar
Fnord
Major General
Major General
 
Posts: 2244
Joined: Tue Feb 13, 2007 9:20 pm
Location: Pripyat
Reputation: 7

Unread postAuthor: mopherman » Fri Jul 20, 2007 5:19 pm

PVC Arsenal 17 wrote:What exactly is DDT? I know it something like Deflagration to Detonation Transition... but wha exactly is it?

it is when things transform from a high powered fizzle to a much more powerfull blast. It generates more pressure and destroys week pipe.
feel free to correct me if im wrong
  • 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: DYI » Fri Jul 20, 2007 5:27 pm

It doesn't necessarily generate a whole lot more pressure (I heard a 50 bar estimate somewhere), it is the rapid spike which causes the real destruction, as most materials don't have the impact strength to survive it. DDT is when the flamefront excedes the speed of sound in whatever medium it is in. The rapid expansion compresses and autoignites the gases in front of it, causing the flamefront to propagate much more rapidly. OR, at least thats how I understand it. Depending on the material, it is also capable of destroying not-so-weak pipe (look at noname's test on 1/2" Sch 80 steel).
  • 0

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: Fnord » Sat Jul 21, 2007 1:49 pm

DYI: the valve is the same as any other piston valve, only steel. The interior of the barrel is rough, but I don't think the friction is enough to be noticeable.
DDT was found to generate 50 bar under normal atmospheric pressure. I'm not sure what ddt will do in a compressed gas enviroment. Right now I'm probably working with pressures of about 30 bar.

Jon89: since you probably didn't read it all, I said the total cost was about $40.

PVC arsenal: The pop-off opens, but I haven't been able to measure the peformance increase it gives. It probably does help a little, but nothing drastic.

Morpherman: read above^

Lukemc: The mauler was more powerful for a number of reasons; such as, it used a burst disk, there was no flow restriction between the chamber and barrel, and the barrel diameter allowed more energy to be exerted on the projectile.
However, I can put mixes in this gun that would probably destroy the mauler, so in the end I guess mine has the most potential power of the two.
Oh, and the mauler doesnt exsist anymore, so I win :P

Felex: I can use a bicycle pump on it, but at home I use my compressor for the convenience of it.

SB15:
1. I may be able to clean the wiring up a bit, but most of my friends think it looks cooler because it's so crappy. It wasn't really meant to have asthetic appeal, it was just meant to have the most power in the smallest space possible.
2. Actually, it's not epoxy, it's soldered (very badly). I didn't want to use a tee because the pipe nipple had the perfect volume already(it was 4.2 percent of the chamber volume)
3. If I take the hose off quickly, it doesn't really effect anything. I usually bleed out the pressure from the schrader behind the piston so no gas is lost.

Thanks for the comments everyone.
  • 0

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

PreviousNext

Return to Hybrid Cannon Database

Who is online

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

Reputation System ©'