Lurch1962

12-27-2007, 06:09 PM

More navel gazing?? http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

The Doppler shifting of sounds in the game has got me to thinking. Given the speeds of planes and bullets, there should be a very significant variation in hitting power (and, to a lesser extent, weight of fire per unit time) when relative aspects/speeds change.

To take a not atypical case; a 300kt fighter vs a 200kt bomber, with the former firing in a head-on run, and the latter's rear gunner firing back while said fighter retreats.

Let's take the muzzle velocity of most aerial ordnance to be about 800m/s. A plane's speed in m/s = knots/2. So our 300kt fighter's velocity is 150m/s, and the bomber's is 100m/s; the combined velocities are 250m/s.

So a bullet's relative velocity in a head-on attack is 800 + 250 = 1050m/s, and when separating is 800 - 250 = 550m/s. The difference between the two cases is 1050 - 550 = 500m/s. A better way to look at is 800 +/- 250m/s (800m/s +/- 31%).

For the fighter pilot, you can see that for a given duration of fire, the rounds hit 31% more rapidly in the head-on run as opposed to a co-speed, tail-on attack.

While the effective rate of fire does differ a fair bit, the hitting power really differs. The kinetic energy of a projectile varies as the square of the velocity, and hence a 31% change in velocity results in a change in hitting power by more than a factor of two!.

The relative hitting power as velocity changes:

550m/s (let's use 5.5 squared): 27.5

800m/s (let's use 8 squared): 64

1050m/s (let's use 10.5 squared): 110.25

I wonder if this is modeled?

The Doppler shifting of sounds in the game has got me to thinking. Given the speeds of planes and bullets, there should be a very significant variation in hitting power (and, to a lesser extent, weight of fire per unit time) when relative aspects/speeds change.

To take a not atypical case; a 300kt fighter vs a 200kt bomber, with the former firing in a head-on run, and the latter's rear gunner firing back while said fighter retreats.

Let's take the muzzle velocity of most aerial ordnance to be about 800m/s. A plane's speed in m/s = knots/2. So our 300kt fighter's velocity is 150m/s, and the bomber's is 100m/s; the combined velocities are 250m/s.

So a bullet's relative velocity in a head-on attack is 800 + 250 = 1050m/s, and when separating is 800 - 250 = 550m/s. The difference between the two cases is 1050 - 550 = 500m/s. A better way to look at is 800 +/- 250m/s (800m/s +/- 31%).

For the fighter pilot, you can see that for a given duration of fire, the rounds hit 31% more rapidly in the head-on run as opposed to a co-speed, tail-on attack.

While the effective rate of fire does differ a fair bit, the hitting power really differs. The kinetic energy of a projectile varies as the square of the velocity, and hence a 31% change in velocity results in a change in hitting power by more than a factor of two!.

The relative hitting power as velocity changes:

550m/s (let's use 5.5 squared): 27.5

800m/s (let's use 8 squared): 64

1050m/s (let's use 10.5 squared): 110.25

I wonder if this is modeled?