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 48 users online :: 5 registered, 0 hidden and 43 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

"In the world of spuds today"

A place to ask general spud cannon related questions.
Sponsored 
  • Author
    Message

Unread postAuthor: jimmy101 » Sun Jun 19, 2011 5:41 pm

Technician1002 wrote:Due to the physics involved in a hybrid, air is too dense to provide velocities very much above the speed of sound.

Though given the temperature dependence of the SOS (and the near independence of the SOS on density), the SOS inside a hybrid is a lot higher than ~300m/s (1100ft/sec)

SOS in air at 700C is about 2x that in air at 20C.
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3129
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Unread postAuthor: HACKERZLORD007 » Mon Jun 20, 2011 3:25 am

Hey Guys ,

Im got a little doubt abt spud guns and all so just wanted a bit of help.....

How much pressure approximately does a hybrid cannon generate? and is it possible to build a pneumatic cannon which can beat a hybrid cannon in performance and muzzle velocity?

Help Would be appreciated!

CHEERS
  • 0


HACKERZLORD007
Private
Private
 
Posts: 14
Joined: Tue Jun 07, 2011 10:49 pm
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Mon Jun 20, 2011 6:12 am

HACKERZLORD007 wrote:How much pressure approximately does a hybrid cannon generate?


The accepted wisdom is approximately 100 psi per mix number, though this is a very general rule of thumb. HGDT is a more educated way of guessing :)

and is it possible to build a pneumatic cannon which can beat a hybrid cannon in performance and muzzle velocity?


How long is a piece of string?

You can always build a more powerful pneumatic, but chances are it will be bigger and more complex than the equivalent hybrid - and if you want high supersonic velocity, pneumatics are limited by physics well below 2000 feet per second.
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Unread postAuthor: MrCrowley » Mon Jun 20, 2011 7:07 am

HACKERZLORD007 wrote:I was wondering if there was any way to build a pneumatic gun which could either match the performance and muzzle velocity of a hybrid gun

Technician1002 wrote:Due to the physics involved in a hybrid, air is too dense to provide velocities very much above the speed of sound.

With heavy dense projectiles air does fine as the heat of combustion is relatively short in duration.

With lighter projectiles, an air cannon won't match a hybrid.

saefroch wrote:It depends on what the construction of both is, and what mix the hybrid is running at as compared to the pressure the pneumatic is running at. But... if I were to have two identical builds, and run them as close to failure as I felt comfortable, the hybrid would best the pneumatic.

If you're trying to beat out a hybrid with a pneumatic, we may or may not be able to help. We'd need more information.

jimmy101 wrote:Though given the temperature dependence of the SOS (and the near independence of the SOS on density), the SOS inside a hybrid is a lot higher than ~300m/s (1100ft/sec)

SOS in air at 700C is about 2x that in air at 20C.

jackssmirkingrevenge wrote:
HACKERZLORD007 wrote:and is it possible to build a pneumatic cannon which can beat a hybrid cannon in performance and muzzle velocity?


How long is a piece of string?

You can always build a more powerful pneumatic, but chances are it will be bigger and more complex than the equivalent hybrid - and if you want high supersonic velocity, pneumatics are limited by physics well below 2000 feet per second.

HACKERZLORD007 wrote:is it possible to build a pneumatic cannon which can beat a hybrid cannon in performance and muzzle velocity?


_______________________________

HACKERZLORD007 wrote:"how do i increase the velocity of my pneumatic gun....it has a 30 cubic inch chamber.....do i increase the chamber volume or do i use higher pressure....(current pressure: 100-150 due to 12 v compressor)????

MrCrowley wrote:Usually with pneumatics, increasing the barrel length or pressure would increase velocity.

Download GGDT (google search for it if you don't know what it is) and plug your cannon's parameters in and see what it says. It's a program for modelling cannons and is dead simple to use. Just read the FAQs on the website.


An hour later...


HACKERZLORD007 wrote:just wanted to confirm how i could increase the muzzle velocity of my pneumatic rifle ????

Should i try increasing the chamber volume or should i try increasing the chamber pressure???
(Currently running 30 cubic inches at 150 psi)

Help Needed......thnx!!!!
CHEERS

Tobin wrote:What is most efficient depends on the barrel. How long barrel u have and what is the diameter at the barrel?

Gun Freak wrote:Yeah we need more specfications like barrel length, chamber length/diameter, valve...

saefroch wrote:Both will do it, but I'd suggest increasing pressure since that's usually easier, but not if you'd be pushing the pressure rating on components.

jackssmirkingrevenge wrote:Increasing chamber volume is effective up to a point, after that could can double the volume and only get a 1% increase in velocity. Increasing pressure on the other hand should give a roughly linear increase in power.

Download Gas Gun Design Tool and have a play before cutting.

Tobin wrote:Then increased chambervolume wont make any noticable difference :)


Three days later...

HACKERZLORD007 wrote:I recently started spudding as a hobby and i started off by making a pneumatic spud. I made one with totally galvanized fittings and pipes. My gun has a 30 cubic inch tank and a half inch bore! Well i was wondering how i can improve the range and velocity of my air gun? Should i use a bigger chamber or should i increase the pressure? (Current Pressure - 150 psi)?? I can shoot a double a battery a good 70-100 on abt 150-160 psi but i want like about 200 mts range and abt 500+ fps...so wht shd i do to improve my gun performance to this standards???? NEED HELP!!!


MrCrowley wrote:HACKERZLORD007,

PM me. Not sure why you posted this twice (as well as PMing me and asking me the same question).

Do your own research, you have been given a wealth of information from several members, more than enough to hit the ground running. I don't want to see you asking this question again.




This guy has a habit of posting his questions multiple times in multiple threads that are not his nor relevant to his questions while managing to ignore a majority of the information supplied and answers to his questions. I've shot a PM off to him so while I find out what the deal is, you might want to save your breath rather than answer his questions.
  • 0

User avatar
MrCrowley
Moderator
Moderator
 
Posts: 10207
Joined: Fri Jun 23, 2006 10:42 pm
Location: Auckland, New Zealand
Country: New Zealand (nz)
Reputation: 4

Unread postAuthor: Labtecpower » Tue Jun 21, 2011 7:57 am

Shot a water bottle today.

[youtube]http://www.youtube.com/watch?v=RWiyT3ZHlF4[/youtube]

You can hear me breathing, because I just had a 3 min workout to pressurize the air chamber with a bicycle pump :D

I also got a nice frame:

Image

The whole garden was covered in potato pieces after this :D
  • 0

"ñøw mÿ šįg šüçkś!"
User avatar
Labtecpower
Major General
Major General
 
Posts: 1267
Joined: Sat Feb 20, 2010 6:38 am
Location: Herb Island
Reputation: 7

Unread postAuthor: Labtecpower » Thu Jun 23, 2011 7:23 am

sorry for double posting

I want to make a large hybrid, so I wanted to practice some with fueling and igniting.
I made a crude and ugly version of the hybrids JSR makes.

The whole thing. Don't pay attention to my crappy epoxy skillz :D

Image

Fill valve close-up

Image

Internals with spark gap

Image

When the epoxy is fully hardened, I will put in the burst-disk holder. It's an electrical connector I got from school. It is made from plastic, but I have some stainless steel versions lying around.
  • 0

"ñøw mÿ šįg šüçkś!"
User avatar
Labtecpower
Major General
Major General
 
Posts: 1267
Joined: Sat Feb 20, 2010 6:38 am
Location: Herb Island
Reputation: 7

Unread postAuthor: saefroch » Thu Jun 23, 2011 10:45 am

WOW. That still is picturesque.

I'm familiar with the workout. I recommend a two-stage pump or an electronic compressor or some sort.
  • 0

User avatar
saefroch
Major General
Major General
 
Posts: 1679
Joined: Mon Jun 08, 2009 8:47 am
Location: U.S.A.- See Map
Country: United States (us)
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: Labtecpower » Thu Jun 23, 2011 11:16 am

I'm pretty happy with it!

Also, a compressor isn't necessary, It's healthy to be active :D
  • 0

"ñøw mÿ šįg šüçkś!"
User avatar
Labtecpower
Major General
Major General
 
Posts: 1267
Joined: Sat Feb 20, 2010 6:38 am
Location: Herb Island
Reputation: 7

Unread postAuthor: DYI » Thu Jul 21, 2011 8:37 pm

ITWOSY: ten hours of work and five pounds of insulation later, the capacitor bank can now be charged to ~14kJ at 24kV without any hissing, arcing, or destruction of multimeters. How well the rest of the equipment in the circuit fares at these discharge energies will be determined in the very near future...
  • 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: jackssmirkingrevenge » Thu Jul 21, 2011 9:56 pm

Labtecpower wrote:I want to make a large hybrid, so I wanted to practice some with fueling and igniting.
I made a crude and ugly version of the hybrids JSR makes.


Haha excellent!

Some objections:

- what's the screw for? If it's for filling, You could just do it through the burst disk holder.

- your spark gap is a little large, what mixes were you planning on going to and with what ignition source?
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Unread postAuthor: ramses » Fri Jul 22, 2011 8:54 am

DYI wrote:ITWOSY: ten hours of work and five pounds of insulation later, the capacitor bank can now be charged to ~14kJ at 24kV without any hissing, arcing, or destruction of multimeters. How well the rest of the equipment in the circuit fares at these discharge energies will be determined in the very near future...


So where was it arcing? Or did you just say "screw it" and pot all the terminals?
  • 0

POLAND_SPUD wrote:even if there was no link I'd know it's a bot because of female name :D
User avatar
ramses
Major General
Major General
 
Posts: 1679
Joined: Thu May 29, 2008 6:50 pm
Reputation: 3

Unread postAuthor: Crna Legija » Sun Jul 24, 2011 7:03 am

ITWOST, I started making a hybrid, just to see if i can get the mix right. If I do I'd like to start on a 3/4 or 1'' tee piston hybrid.


bit of a crappy epoxy job, didn't have enough to get a nice glassy finish on the end lol but theirs nearly 20mm of it there.
  • 0

Attachments
P7160042.JPG
tomorrow ill get a union from work and more epoxy.
P7160042.JPG (11.09 KiB) Viewed 356 times
'' To alcohol... The cause of, and solution to, all of life's problems.”
--Homer Simpson

Add me on ps3: wannafuk, 8/11/11 cant wait
User avatar
Crna Legija
Major General
Major General
 
Posts: 2333
Joined: Sun Jul 20, 2008 5:14 am
Location: australia
Reputation: 0

Unread postAuthor: Gun Freak » Sun Jul 24, 2011 12:12 pm

ITWOST... After the original on/off switch wore out on my bench grinder, I searched for a replacement, only to find out that a replacement switch costs 35 dollars, half the cost of a new grinder. So I bought a 4$ toggle switch at home depot and fashioned a mount out of plastic (using the bench grinder with the switch haning off 8) ). I'm happy with it :D
Image
  • 0

OG Anti-Hybrid
One man's trash is a true Spudder's treasure!
Golf Ball Cannon "Superna"M16 BBMGPengunHammer Valve Airsoft SniperHigh Pressure .22 Coax
Holy Shat!
User avatar
Gun Freak
Lieutenant General
Lieutenant General
 
Posts: 4969
Joined: Mon Jan 25, 2010 4:38 pm
Location: Florida
Country: United States (us)
Reputation: 11

Unread postAuthor: mattyzip77 » Sun Jul 24, 2011 2:26 pm

Good job and good idea!!! You could have even rigged it so you could just use the plug to turn it on and off!! You probably knew that though, but maybe not.
  • 0

User avatar
mattyzip77
Donating Member
Donating Member
 
Posts: 1249
Joined: Tue Jun 28, 2011 12:22 pm
Location: Taxachusetts
Reputation: 0

Unread postAuthor: irisher » Tue Aug 09, 2011 10:06 pm

ITWOST: My 1 lb bag of military surplus flechettes arrived. It is quite fun against plywood.
  • 0

Si vis pacem , constructum tartufoli ornamentum
User avatar
irisher
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 420
Joined: Mon Dec 29, 2008 2:53 am
Reputation: 0

PreviousNext

Return to General Spud Cannon Related

Who is online

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

Reputation System ©'