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 52 users online :: 5 registered, 0 hidden and 47 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

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

Super sonic Potato Gun

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

Super sonic Potato Gun

Unread postAuthor: cannon freak » Fri May 12, 2006 9:18 pm

I was wondering if anyone could help me with building a super sonic potato gun. I would really like to know if there is any mathimatical equation to take the volume and pressure of the pressure vesel and use that to find out how long the barrel will have to be for a certain speed.
  • 0


cannon freak
1st Lieutenant
1st Lieutenant
 
Posts: 272
Joined: Fri May 12, 2006 8:37 pm
Location: New Brunswick, Canada
Reputation: 0

Unread postAuthor: drac » Fri May 12, 2006 9:44 pm

It takes a good knowledge of thermal dynamics and physics to figure that out. Your best bet would be to use the Gas Gun Design Tool, downloadable in the Tools/Calculators Section.
  • 0

User avatar
drac
Moderator
Moderator
 
Posts: 916
Joined: Sun Apr 24, 2005 8:56 am
Location: North Collins, NY
Country: United States (us)
Reputation: 2

Unread postAuthor: Pete Zaria » Fri May 12, 2006 11:44 pm

Speed of sound at sea level is 714 MPH, or 340.29 m / s. Use the GGDT or similar as Drac suggested to calculate what you'd need to get there. You'll either need a huge pnumatic with a golfball barrel or a hybrid. Don't mess with hybrids unless you REALLY know what you're doing.

Peace,
Pete Zaria.
  • 0

User avatar
Pete Zaria
Moderator
Moderator
 
Posts: 978
Joined: Fri Mar 31, 2006 6:04 pm
Location: Near Seattle, WA
Reputation: 0

Unread postAuthor: A-98 » Sat May 13, 2006 12:22 am

why a golf ball barrel?

but yes i think you would need a hybrid...a big one....and i wouldnt go there unless you really know what your doing
  • 0

User avatar
A-98
Brigadier General
Brigadier General
 
Posts: 921
Joined: Thu Apr 27, 2006 7:41 pm
Location: Santa Barbara, CA
Reputation: 0

Unread postAuthor: rna_duelers » Sat May 13, 2006 2:59 am

It's impossible to make a pneumatic go obove the speed of sound with usual air,you need to use a different type of gas heluim or Co2 to reach the speed of sound and it can be done with a small piston gun and a marble quite easily.
  • 0

Image
User avatar
rna_duelers
Major General
Major General
 
Posts: 1740
Joined: Mon Sep 26, 2005 7:07 am
Location: G-land Australia
Country: Australia (au)
Reputation: 1

Unread postAuthor: cannon freak » Sat May 13, 2006 7:29 am

For what reason can you not use regular air to reach the speed of sound, and what is the Gas Gun Design tool.
  • 0


cannon freak
1st Lieutenant
1st Lieutenant
 
Posts: 272
Joined: Fri May 12, 2006 8:37 pm
Location: New Brunswick, Canada
Reputation: 0

Unread postAuthor: boilingleadbath » Sat May 13, 2006 3:59 pm

Google: "Gas Gun Design Tool"

The reason is too hard to explain to bother wasting my time telling someone who can't even be arsed to UTFSE!
  • 0

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

Sponsored

Sponsor
 


Unread postAuthor: zvallance1 » Sat May 13, 2006 11:27 pm

boilingleadbath wrote:Google: "Gas Gun Design Tool"

The reason is too hard to explain to bother wasting my time telling someone who can't even be arsed to UTFSE!


utfse = use the freakin search engine?

anyways, i'd kinda like to know, myself..
something to do with valve opening time, and that since air can only go so fast(maybe ONLY the speed of sound) the valve slows it too much to actually break the sound barrier.
just a guess though, please enlighten us?
  • 0


zvallance1
Sergeant
Sergeant
 
Posts: 94
Joined: Wed Dec 21, 2005 11:34 pm
Reputation: 0

Unread postAuthor: boilingleadbath » Sun May 14, 2006 1:19 am

Yes, zvallance, UTFSE = use the freakin search engine

And you basicaly got it; air is limmeted to the speed of sound, and (even with a perfect valve) the amount of force it could apply to the projectile trails off as it gets closer and closer to that speed - and thus you never quite reach it.

Note that because the speed of sound increases with gas temperature, and the propellent gas is heated by shocks and friction in the barrel, 'supersonic' - compared to the outside air, not that in the barrel - projectiles acctualy are possible with normal air.
It's just that the very slight degree by which they are supersonic isn't worth the extra hassle.

Incidentaly, the only gasses that can push a projectile past the speed of sound in air are hydrogen, helium, and possibly nitrogen.
CO<sub>2</sub> acctualy is limmeted to providing mach .85
  • 0

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

Unread postAuthor: rna_duelers » Sun May 14, 2006 6:12 am

Ohh well you learn something everyday CO2 is limmited below the sound barrier.
  • 0

Image
User avatar
rna_duelers
Major General
Major General
 
Posts: 1740
Joined: Mon Sep 26, 2005 7:07 am
Location: G-land Australia
Country: Australia (au)
Reputation: 1

Unread postAuthor: WOW!! » Thu May 25, 2006 3:12 pm

Iam building a Hybrid, when I get it up and working Ill let you know if i hit supersonic. What does that sound like? A sonic booom?



Josh
  • 0

User avatar
WOW!!
Brigadier General
Brigadier General
 
Posts: 889
Joined: Thu Mar 16, 2006 9:47 pm
Location: New jersey
Reputation: 0

Unread postAuthor: mnrocketman » Tue Aug 01, 2006 10:36 pm

Any sonic boom would be covered up by the explosion in the combustion chamber. An example is a .22 bullet-it goes past the speed of sound, but no sonic boom.
  • 0


mnrocketman
Private
Private
 
Posts: 5
Joined: Fri Jul 28, 2006 7:19 pm
Reputation: 0

Unread postAuthor: benstern » Tue Aug 01, 2006 11:04 pm

Try to post things that would help people in the present time not a few months back.
  • 0

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

Unread postAuthor: M3NT4L » Wed Aug 02, 2006 12:25 am

Im sorry but does anybody here have any pictures or better yet videos of supersonic cannons, any links. Because i have searched this manytimes but its like a myth, there are articles but no pics or storys.
  • 0

Image
User avatar
M3NT4L
2nd Lieutenant
2nd Lieutenant
 
Posts: 239
Joined: Wed Jul 05, 2006 7:40 pm
Reputation: 0

Unread postAuthor: djt » Wed Aug 02, 2006 12:32 am

joels cannon on spudtech. its pretty simple too. i guess supah valve + long barrel = supersonic pneumatic cannon! i dont know if there is really proof of it but i dont think joel would lie on something like that.
  • 0


djt
Major
Major
 
Posts: 387
Joined: Sat Mar 11, 2006 4:30 pm
Reputation: 0

Next

Return to General Spud Cannon Related

Who is online

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

Reputation System ©'