balistic coeficiant?
09-04-2003, 11:22 PM
#2
Nontypical Buck
Join Date: Feb 2003
Location: Coralville, IA. USA
Posts: 3,802
RE: balistic coeficiant?
Try the following links for more detailed articles.
Here' s the basic gist...
Ballistic Coefficient (BC) is a numerical representation of how aerodynamic a bullet is, or more simply, how well the bullet plows through the air. Usually the BC of a bullet is a decimal value somewhere between 0 and 1, with the higher number representing more aerodynamic bullet. The higher the BC the less rapidly the bullet will lose velocity and the less it will drift in a given wind.
Sectional Density (SD) is a the ratio of the bullets weight to its frontal area (well kindof). The accepted equation for calculating SD is SD= [(bullet weight in grains/7000)/(bullet diameter)^2]. I say kindof because the actual area of a circle is represented by the equation Area=Pi x (radius)^2, not (diameter)^2. But it' s the accepted method and it provides a means to compare bullets. Anyway, math issues aside, the SD is basically a way to measure the ability of a bullet to penetrate, all else equal. Take two identically constructed bullets with different SD' s, the one with the higher SD will usually penetrate deeper. A long thin bullet will generally penetrate deeper than a short fat one. For an extreme example of SD in action research the M1A1 Abrams tank and it' s 120mm High Velocity fin-stabilized discarding sabot round. The projectile is about 2 feet long and about 1" in diameter and weighs several pounds (it' s made of depleted Uranium or Tungsten Carbide). It' ll go clean through almost any main battle tank fielded today, blowing it to pieces in the process.
Anyway, for more info go to the following links:
http://www.chuckhawks.com/bc.htm
and
http://www.chuckhawks.com/sd.htm
Here' s the basic gist...
Ballistic Coefficient (BC) is a numerical representation of how aerodynamic a bullet is, or more simply, how well the bullet plows through the air. Usually the BC of a bullet is a decimal value somewhere between 0 and 1, with the higher number representing more aerodynamic bullet. The higher the BC the less rapidly the bullet will lose velocity and the less it will drift in a given wind.
Sectional Density (SD) is a the ratio of the bullets weight to its frontal area (well kindof). The accepted equation for calculating SD is SD= [(bullet weight in grains/7000)/(bullet diameter)^2]. I say kindof because the actual area of a circle is represented by the equation Area=Pi x (radius)^2, not (diameter)^2. But it' s the accepted method and it provides a means to compare bullets. Anyway, math issues aside, the SD is basically a way to measure the ability of a bullet to penetrate, all else equal. Take two identically constructed bullets with different SD' s, the one with the higher SD will usually penetrate deeper. A long thin bullet will generally penetrate deeper than a short fat one. For an extreme example of SD in action research the M1A1 Abrams tank and it' s 120mm High Velocity fin-stabilized discarding sabot round. The projectile is about 2 feet long and about 1" in diameter and weighs several pounds (it' s made of depleted Uranium or Tungsten Carbide). It' ll go clean through almost any main battle tank fielded today, blowing it to pieces in the process.
Anyway, for more info go to the following links:
http://www.chuckhawks.com/bc.htm
and
http://www.chuckhawks.com/sd.htm
09-05-2003, 07:52 AM
#3
Giant Nontypical
Join Date: Feb 2003
Location: fort mcmurray alberta canada
Posts: 5,667
RE: balistic coeficiant?
Sectional density used to used to judge a bullets penetration potential.This still applies to a certain extent with conventional bullets but premium bullets of different construction do differ in their performance.With bullets such as the partition or failsafe the lighter bullets tend to penetrate just as well as the identical bullets with higher sectional density.
