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 70 users online :: 4 registered, 0 hidden and 66 guests


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

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

The Team
Administrators
Global Moderators
global_moderators.png CS

Killjoy's FEAR

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 
  • Author
    Message

Unread postAuthor: Killjoy » Wed Apr 25, 2007 1:48 pm

Thanks for the comments you guy

I am trying to find time to redo the tests, but i have tests and a lot of school work and stuff i need to do for my employer, but hopefully i can do some tests this weekend.
The golfballs were not going 2700 fps, they were actually goin 1500 fps, mainly because i didn't feel like properly wadding them in the barrel.

The barrel slides foreward because the way i attached it to the burst disk holder was not very effective, and the pvc barrel was constantly ripping out of the holder due to the force of the expanding gases. Its been fixed though so the barrel should stop moving forward.

Oh and sorry about the junk, as soon as i finished the project my parents made me clean up the rest of the house and back yard, and everything ended up in my garage, but i should have some clearer pics by the end of this weekend if i do get a chance to fire this cannon again.
  • 0


Killjoy
Brigadier General
Brigadier General
 
Posts: 1053
Joined: Sun Nov 12, 2006 12:51 am
Location: New Mexico
Reputation: 0

Unread postAuthor: paaiyan » Wed Apr 25, 2007 2:20 pm

That is a beast. You should try packing in some lead sinkers with good wadding, I'd wanna see the damage from that.
  • 0

"Who ever said the pen was mightier than the sword, obviously, never encountered automatic weapons."
-General Douglass MacArthur

Read my dog's blog - Life of Kilo
User avatar
paaiyan
Major General
Major General
 
Posts: 2140
Joined: Wed Dec 27, 2006 10:03 pm
Location: Central Oklahoma
Country: United States (us)
Reputation: 1

Unread postAuthor: Killjoy » Wed Apr 25, 2007 4:32 pm

Well actually i have a whole bunch of 1" steel ball bearings i was planning to use...
  • 0


Killjoy
Brigadier General
Brigadier General
 
Posts: 1053
Joined: Sun Nov 12, 2006 12:51 am
Location: New Mexico
Reputation: 0

Unread postAuthor: paaiyan » Wed Apr 25, 2007 4:36 pm

Oh hey, that works too. You know what else would be awesome, get one of those packages of .177 BB's and load a buttload of them in it, like a puntgun, haha.
  • 0

"Who ever said the pen was mightier than the sword, obviously, never encountered automatic weapons."
-General Douglass MacArthur

Read my dog's blog - Life of Kilo
User avatar
paaiyan
Major General
Major General
 
Posts: 2140
Joined: Wed Dec 27, 2006 10:03 pm
Location: Central Oklahoma
Country: United States (us)
Reputation: 1

Unread postAuthor: AmYisroelChai » Wed Apr 25, 2007 4:49 pm

Just signng in to say very nice cannon.
Good work. Keep us informed of all the stats.
  • 0


AmYisroelChai
Staff Sergeant
Staff Sergeant
 
Posts: 117
Joined: Thu Mar 29, 2007 10:50 am
Reputation: 0

Unread postAuthor: SpudBlaster15 » Wed Apr 25, 2007 5:44 pm

I think we have a contest winner! Amazing job Killjoy, you have my vote thus far.

jackssmirkingrevenge wrote:The longest range black power rifles won't exceed 2,000 feet per second, I find it hard to believe that a mix of propane and air can do better.


Are the barrels of said black powder rifles FIFTY FEET long? I don't think so. The 2700fps figure sounds accurate for a 4x hybrid launcher of this scale.
  • 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: Hotwired » Wed Apr 25, 2007 8:00 pm

SpudBlaster15 wrote:
jackssmirkingrevenge wrote:The longest range black power rifles won't exceed 2,000 feet per second, I find it hard to believe that a mix of propane and air can do better.

Are the barrels of said black powder rifles FIFTY FEET long? I don't think so. The 2700fps figure sounds accurate for a 4x hybrid launcher of this scale.

Put a fifty foot barrel on a rifle and the drag will kill the bullets speed, not make it go faster.

The best modern sniper rifles don't do more than 900m/s (~2900fps) and thats with the massive acceleration from around 50,000psi of hot combustion gases.

The .50 rifle shown earlier does 2700fps
The chrony reading for the potato also showed 2700fps

I'm an engineering type so it's in my nature to doubt the ability of a possibly disintegrating potato of large diameter to be travelling at the same speed as a much thinner, aerodynamic bullet fired from the most powerful sniper rifles around.

The speed in question being almost three times the speed of sound.

Ask yourself what kind of materials and shapes you know of that can go that fast - missiles, bullets, some jets - then consider a 2" potato slug which has just passed through fifty feet of pipe.

Thats why I suggested the chronographing of a blank fire and a solid round of equal mass. I'll accept the readings from that when they happen.


ShowNoMercy of course I'm jealous, I'd be looking at the inside of a police car within half an hour if I tried to fire something as big and powerful as this round my place :P
  • 0

User avatar
Hotwired
Lieutenant General
Lieutenant General
 
Posts: 2599
Joined: Fri Oct 13, 2006 5:51 am
Location: UK
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: YElloW » Wed Apr 25, 2007 9:02 pm

Kill joy, your barrel is a bit long, you might get better results from a 25-30 foot barrel, also, in reality, your best shot from the cannon would probably have a speed of 2000 fps to 2300 fps with a golf ball, which would have the KE of 15,000J-21,000J. You might be able to get better penetration and speed from a finned steel sabot which I can tell you how to make, if you want to know. Besides your choice of ammunition, you have a superb cannon, which none will match.

You have my vote as the best cannon. I love how you have everything electronically controlled, just get me some more pictures.
  • 0


YElloW
Private
Private
 
Posts: 3
Joined: Sun Apr 01, 2007 8:05 pm
Reputation: 0

Unread postAuthor: Killjoy » Wed Apr 25, 2007 10:14 pm

Thanks spudblaster.

Hotwired,
I understand your reasons for questioning the results, and am currently trying to make time to test and make sure i have not made any mistakes and that the recorded velocity is accurate, or maybe not.

Yellow,
The barrel in my opinion is not overly long, i still have about a 1 to 1 ratio which should work fine, and it does so i am content with the barrel length, but thanks for your suggestion.
The finned sabot is agood idea though, might try that some time.
Thanks for your vote by the way.
  • 0


Killjoy
Brigadier General
Brigadier General
 
Posts: 1053
Joined: Sun Nov 12, 2006 12:51 am
Location: New Mexico
Reputation: 0

Unread postAuthor: SpudBlaster15 » Thu Apr 26, 2007 1:07 am

Hotwired wrote:Put a fifty foot barrel on a rifle and the drag will kill the bullets speed, not make it go faster.


This is the secondary aspect of my point. Such is the case because the propellant cannot deliver enough energy to the projectile to accelerate it down a 50 foot barrel, unlike in the case of Killjoy's gun.

Do you realize how much energy a potato slug gains as it is accelerated down the length of a 50 foot pipe by an average of ~220psi?

Hotwired wrote:The best modern sniper rifles don't do more than 900m/s (~2900fps) and thats with the massive acceleration from around 50,000psi of hot combustion gases.


Acceleration is derived from both pressure, and the length of time this pressure has to act on the projectile. The barrel of a sniper rifle does not provide much time to accelerate.

Hotwired wrote:I'm an engineering type so it's in my nature to doubt the ability of a possibly disintegrating potato of large diameter to be travelling at the same speed as a much thinner, aerodynamic bullet fired from the most powerful sniper rifles around.


Why wouldn't a potato be capable of traveling at such speeds? Given the barrel length, the acceleration would be gradual, the potato should not disintegrate.

Hotwired wrote:Ask yourself what kind of materials and shapes you know of that can go that fast - missiles, bullets, some jets - then consider a 2" potato slug which has just passed through fifty feet of pipe.


Again, why couldn't a potato slug, given enough chamber energy and a barrel to utilize it, be accelerated to the same speed as any of your 'shapes'? You are not thinking logically my friend. Kinetic energy is kinetic energy.
  • 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: Hotwired » Thu Apr 26, 2007 4:39 am

I'm not going to requote all of that or deviate from what I'm trying to say so:

For a 100g slug of potato, 50 feet of 2" pipe and a house sized volume of 220psi air GGDT says about 9000J and 1400fps. For a 50g slug with the same launcher: 8586J and 1923fps.

I think the 2700fps reading was from particles of potato which were taken off the slug through the friction of the barrel.

Nothing more I can say right now but I hope the cannon does well in the competition :)
  • 0

User avatar
Hotwired
Lieutenant General
Lieutenant General
 
Posts: 2599
Joined: Fri Oct 13, 2006 5:51 am
Location: UK
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Thu Apr 26, 2007 5:18 am

All this debate is in the air and superflous until killjoy manages to chrono a series of solid projectiles far enough from the muzzle for the blast effect to be negated.

Data is irrelevant unless its repeatable.
  • 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: DYI » Sun Sep 16, 2007 8:19 am

Sorry for kicking this up, but I was looking at the thread and saw Hotwired's GGDT numbers, so I input the parameters of this cannon and got exactly 2700 fps and 12488 ft/lbs for a 50 gram projectile, with 300psi CO2 at 3500 degrees farhenheit. These numbers are obviously not perfectly accurate, since the combustion produces CO2 and H2O, and doesn't occur instantly, and GGDT isn't the most accurate with supersonic projectile velocities, but it would certainly seem as though the 2700 fps number is within the realm of possibility. see SCTBDC-100 thread
  • 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

Previous

Return to Hybrid Cannon Database

Who is online

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

Reputation System ©'