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 57 users online :: 3 registered, 0 hidden and 54 guests


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

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

The Team
Administrators
Global Moderators
global_moderators.png CS

2 questions...once again

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

2 questions...once again

Unread postAuthor: neilman88 » Mon Oct 03, 2005 9:03 pm

1) so the bigger the chamber the more power u will get?

2)if i have a 2 1/2 foot barrel, 1/2 width...how big would my chamber have to be for the best preformance? and how far would it shoot horizontally on a football feld?

my bad for mnumber 2 make it an 3ft long barrel
  • 0

Last edited by neilman88 on Mon Oct 03, 2005 9:16 pm, edited 1 time in total.

neilman88
Sergeant
Sergeant
 
Posts: 84
Joined: Tue Jul 05, 2005 7:53 pm
Reputation: 0

Unread postAuthor: CS » Mon Oct 03, 2005 9:15 pm

1) Basically, but obviously you should keep the ratios in mind because you could have a 4"x20' chamber and a 1"x1' barrel and since the ratio is so far off your ammo wouldnt go anywhere. Know that I think about the flame would go farther then the projectile.

2) Go to burntlatke.com and use his caculator. I could give you a guestamation of how big it should but I would rather help you turn into self suffeciant (that word is freakin hard to spell) spudgunner.
  • 0

User avatar
CS
Donating Moderator
Donating Moderator
 
Posts: 1897
Joined: Fri Feb 18, 2005 5:32 pm
Location: Southern Utah
Country: United States (us)
Reputation: 4

Unread postAuthor: neilman88 » Mon Oct 03, 2005 9:31 pm

sweet i did it! is a ratio of 1:6:1 good? i hope i did it right! awesome i already made plans for my new gun
  • 0


neilman88
Sergeant
Sergeant
 
Posts: 84
Joined: Tue Jul 05, 2005 7:53 pm
Reputation: 0

Unread postAuthor: CS » Mon Oct 03, 2005 9:45 pm

Nice double post :!: Please use the edit button. Its called a C:B ratio (chamber: barrel) So I dont know where you got the third number from. Your c:b ratio should be about 1:1 or 1.5:1. You can toy around with ratios a little bit like thought 6:1 or 1:6 those numbers wouldnt be good.
  • 0

User avatar
CS
Donating Moderator
Donating Moderator
 
Posts: 1897
Joined: Fri Feb 18, 2005 5:32 pm
Location: Southern Utah
Country: United States (us)
Reputation: 4

Unread postAuthor: neilman88 » Mon Oct 03, 2005 10:55 pm

? so it should be around 1.5...?

EDIT:u said 1.1 is good right? cause i messed around and i got that? is that good?
  • 0


neilman88
Sergeant
Sergeant
 
Posts: 84
Joined: Tue Jul 05, 2005 7:53 pm
Reputation: 0

Unread postAuthor: boilingleadbath » Tue Oct 04, 2005 2:46 pm

1) Yeah, big chambers are good. The only exception is when the time the propellent has takes so long that the pressure never gets very high before the ammo has left the barrel. (the empty salt mine scenario)

However, because you are limmeted to a total launcher length, and preformance return on volume invested is deminishing (1:1 -> 2:1 gives a biger improvment than 2:1 -> 3:1), there is an optimum trade-off between long barrel and long chamber. This is an elusive number, dependent on many things; chamber <i>diametr</i>:barrel <i>diameter</i> ratio, fuel, how you figure it out... and is still a tenative branch of study.
... nevermind, I see you are limmeted by barrel length. Just make a big chamber.

2) as big as possible - make the best use of that punny 3' barrel!
  • 0

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

Unread postAuthor: neilman88 » Tue Oct 04, 2005 8:00 pm

awesome thx man so 1:1 is good right? so how good would it be?

so witha a 3ft barrel/9.5'' length, 1 1/2'' width chamber and a ratio of 1:1 its gonna be the best it can be with that chamber size?

EDIT: im a retard its 1:1 not 1.1:1...ok i got it now thx
  • 0


neilman88
Sergeant
Sergeant
 
Posts: 84
Joined: Tue Jul 05, 2005 7:53 pm
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: boilingleadbath » Wed Oct 05, 2005 2:44 pm

Hu?
Your 3' long, .5" diameter barrel with your 9.5" long, 1.5" diameter chamber will give you a ratio of about 2.4:1... acctually, this is probably fairly close to optimum for a 3:1 diameter ratio, if you are seaking max power/overall length.

As a courtousy, could you spend the extra milliseconds and capitalize your letters, and spell out thanks? I spend hundreds of seconds on my posts, which I have posted over and over to previous newbs, just to help you; you can spend a few extra seconds to make your posts look nice. A bit of thought would be nice too - some of your posts are... elesive.
Also, why does your barrel have to be 3'?
  • 0

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

Unread postAuthor: neilman88 » Wed Oct 05, 2005 7:48 pm

sorry

no my 3' long .75'' diameter barrel with my 9.5'' long 1.5'' diameter chamber, on burntlakte C:B ratio finder it said that would be a C:B ratio of 1:1

because for the thing said 36'' barrel was good(1:1) for my gun, with 9.5'' long chamber 1.5'' in diameter

and im saying how good would it be...like as in PSI or FPS?
  • 0


neilman88
Sergeant
Sergeant
 
Posts: 84
Joined: Tue Jul 05, 2005 7:53 pm
Reputation: 0

Unread postAuthor: boilingleadbath » Wed Oct 05, 2005 8:25 pm

...and this is also the first time you have said .75"; re-read you origional post, and you'll find that it says "1/2 width".
I'm going to assume it was a typo (or bad wording) origionaly, in which case - with the bigger diameter barrel, it will indeed give you a 1:1 ratio.

Anyway, you are going about it 'wrong' - unless your bigest chunk of 1.5" pipe is 9.5" long, that is.
You don't enter a random chamber length, and determine how long your barrel has to be to take full advantage of it, because it is much better to design them <i>together</i>, finding the most effective use of your total length. (although 45.5" isn't a bad length now that I think about it.)
Incidentaly, you'd probably get more power/total length if you lengthened the chamber a bit - 50% wouldn't be over kill. (1.5:1 or 1.75:1 is probably about where you want to put the ratio, but it's really quite inexact)

As to power, I'm not really a combustion person, but I'll run some numbers here. Using the GGDT, I find that a marble (6.7 grams?) will be accelerated to a velocity of about 350 feet/sec (I used 45 psi as the pressure). Oddly, it also wants you to make your chamber about 18" long... a bit longer than I was figuring, and possibly wrong - but 14" isn't a bad idea. The benifit is only about 15 feet/sec anyway.
  • 0

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

Unread postAuthor: neilman88 » Wed Oct 05, 2005 8:40 pm

awwww sweet thx for telling me! but i forgot to tell u this(if it makes a difference)i want my gun to be rifle size and be the best it can be for a rifle size gun(not cannon size with 3'' barrel diameter etc.), and ive heard from most people that 1:1 would out preform a 1.5:1 or a 1.7:1, but i dont know

thx for telling me all this info

EDIT:yes i did say 1/2'' sorry for changing on a dime,where did u get that GGDT?
  • 0


neilman88
Sergeant
Sergeant
 
Posts: 84
Joined: Tue Jul 05, 2005 7:53 pm
Reputation: 0

Unread postAuthor: boilingleadbath » Thu Oct 06, 2005 8:45 pm

<a href="http://www1.iwvisp.com/thehalls/GGDT/index.html">GGDT</a>
Really, spread the news: Google is good.
Anyway, it's acctually for pnematic (air-powered) cannons. It <i>can</i> be used to give a (very) rough estimate of combustion preformance.

The acctualy diameter of the barrel doesn't matter in the consideration chamber:barrel ratio, and acctually... 1" isn't overly large bore.
They are right in a way. If you extend your barrel until it is long enough to give you a 1:1 ratio, it will indeed be more powerfull - you have more barrel in which to accelarate the projectile. Does that make sence yet?!
  • 0

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

Return to General Spud Cannon Related

Who is online

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

Reputation System ©'