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 56 users online :: 6 registered, 0 hidden and 50 guests


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

Registered users: anello, 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

1.5" vs. 2"

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
Sponsored 
  • Author
    Message

Unread postAuthor: Solar » Sun Apr 15, 2007 2:56 pm

Any chance of calculating impact of these at say 225 fps? How about for a 1.5" that weighs in at 32 grams?
  • 0

User avatar
Solar
Colonel
Colonel
 
Posts: 512
Joined: Tue May 17, 2005 11:53 pm
Country: United States (us)
Reputation: 11

Unread postAuthor: SpudBlaster15 » Sun Apr 15, 2007 3:28 pm

Kinetic energy can be calculated using KE = 1/2*M*V^2, where M = mass of the projectile in kilograms, and V = the velocity of the projectile in meters per second. So for your inputs,

KE = 1/2*0.032*68.6^2
KE = 75.3J

As for energy density, a 1.6" projectile has pi*0.8^2 = 2.01in^2 of frontal surface area, so the energy delivered to the target per square inch of frontal surface area is 75.3/2.01 = 37.5J. Generally speaking, the higher this number is, the more penetrating ability the round has.
  • 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: Solar » Sun Apr 15, 2007 4:34 pm

What about the density of the object? I am waiting for the density numbers for a foam round. I am sure this delivers (or disperses) energy differently than a potato. Thanks for the info.
  • 0

User avatar
Solar
Colonel
Colonel
 
Posts: 512
Joined: Tue May 17, 2005 11:53 pm
Country: United States (us)
Reputation: 11

Unread postAuthor: SpudBlaster15 » Sun Apr 15, 2007 5:04 pm

Well, the density will effect the mass of a round that displaces a particular volume, thus effecting the kinetic energy calculation, which in turn effects the energy density calculation.

This page shows that Styrofoam has a density of 100 kg/m^3, which converts to 1.64 g/in^3 for ease of calculation. A 1.6" x 2" slug will thusly have a mass of (pi*0.8^2*2)*1.64 = 6.6 grams.

Assuming the same velocity (which will not be the case given an identical launcher), the Styrofoam slug will have a muzzle energy of 1/2*0.0066*68.6^2 = 15.5J, and an energy density of 15.5/2.01 = 7.7J/in^3.

...Of course, a slug with a mass of 6.6 grams will be traveling much faster than one with a mass of 32 grams when fired from the same launcher, and so the energies will be somewhat more similar.
  • 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

Previous

Return to Pneumatic Cannon Discussion

Who is online

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

Reputation System ©'