i still....

[Oglivie]

You can figure muzzle energy or energy at range by knowing the velocity and bullet weight with this formula:

Bullet weight in grains X velocity in feet per second squared / 450240 = energy in foot pounds

Thanks Jagd,

I was tinkering with a little math program for the FPE. Got out the ole Turbo C and compiled a quick little program to mathematically calculate the FPE from your formula. It runs from the Windows Command Prompt. I'm running XP, but think it be fine for other Windows versions. Note that the FPE is rounded out to the nearest whole number.

 

[Jagdflieger]

How cool is that! Thanks Oglivie.

 

[Oglivie]

You're very welcome, Jagd! I think I have some other old C progs I did laying around here on my HD. I think I did some for the CFS2 airbases.dat file. I'll take a look and post them in a bit, maybe they could be useful. If so I'll upload them to the utilities section also.

 

[sc7500]

Recalc ?

I've been tinkering with Oglive's Energy calculator, using it to compare round impact numbers that exist in my DPEd Arms.dat file.

The old [Dice] number comes up almost DOUBLE of the O-Calc number in almost every case, at the estimated 500 yard range built in to DPEd.

Or am I doing this incorrectly ? :isadizzy:

SC

 

[misson]

great!..

Thanks Jagd,

I was tinkering with a little math program for the FPE. Got out the ole Turbo C and compiled a quick little program to mathematically calculate the FPE from your formula. It runs from the Windows Command Prompt. I'm running XP, but think it be fine for other Windows versions. Note that the FPE is rounded out to the nearest whole number.

that is great oglivie! Now not only we have a reference made by Pepe, we have a TOOL!.

 

[Jagdflieger]

SC,

Projectile velocity is retarded quickly by supersonic shock wave drag and surface friction when sub-sonic. That's why pointed-boat tailed bullets perform better at long range than older style round nose bullets (ie. 30/30-32/20, etc.).

I don't think that CFS 2 models drag on projectiles although it does model trajectory. There are a few formulae that predict velocities at various ranges and all are dependent on the following factors:

Sectional Density (diamater compared to weight)

or

SD = W / d squared

Coefficient of Form (how pointed a bullet is)

No formulae available. Live fire testing is required or you can estimate by degree of point to the bullet and if flat base or boat tail.

Sample form factors are: Very sharp = .60, round nose = 1.00

All of this is used to compute the "ballistic coefficient" (BC) of a projectile and how well it retains its velocity over time in flight. An ideal bullet would have a BC of 1.00. That's impossible except in space, so most well designed militery bullets have a BC of around .4 for ball ammo and up to .5 plus for sniper or long range bullets.

An example of military 30 calibre 150 grain bullets (Cal 30 US M2-7.7 Jap-7.62X54 Russian-7.5 French or Swiss) looks like this:

150 grain .308 (7.62mm) cal pointed FMJ bullet:

Muzzle: 2700 FPS
100 Yards: 2500 FPS
200 Yards: 2300 FPS
300 Yards: 2125 FPS
400 Yards: 1950 FPS
500 Yards: 1794 FPS
600 Yards: 1650 FPS

This is all computed for a near sea level altitude. At high altitudes the air is less dense and BCs improve and result in better downrange ballistics due to less drag. Temperature also affects BC.