RexMan

I see a Wartgamer (Watgamer?) but I do not see a Lewis that has posted here. Since I personally am looking into dispersion, a naturally non-perfect phenomena, why would you say that about me. Do you feel the need to try to psychoanalyze people without meeting them? Myself, and others, seem to find this interesting. Is there a personality disorder to describe kill-joy negative personality types like yourself? Or are you just obsessed with trying to point out others problems? Sounds to me you might be among the types you are describing!

Dispersion, in direct fire, can be atributed to velocity variation (projectile comes out faster or slower) as well as non-repeatable gun repositioning. If you were to take a sufficiently rigid barrel, put it in a vise, and ensure that the propellant produces the same reaction (along with things like constant friction within the barrel, etc), then a higher velocity projectile from that setup will be more accurate. That is because the exsternal ballistics it experiences will not be the same. For a set rifling, the higher velocity projectile spins faster, the amount of time it is subject to atmospheric conditions is less, etc. By the way, rifling and spin CAN be too much. You want just enough to stabilize the projectile. Too much has an adverse effect just like too little. It will also wear out faster.

Accuracy has to define a target. Thats so basic as to be funny. When trying to hit a house at 200 meters. Most anything is accurate enough.

I think everyone should do the following test (if interested)... Take a 37mm ATG (or any HV HE chucker) and just area target a point about 200 meters. Use a flat terrain test bed. From the small craters, its obvious that horizontal dispersion is not modeled exactly. From my testing, the placement is way too close.

Then try defining effective if you can not define accuracy.

US tank gunnery indirect fire: The reason I bring up the US tank gunnery emphasis on indirect fire techniques is because it may actually reveal something about the gun system itself. If you have a small target like a 1 meter by 1 meter antitank gun at 3500 meters, thats a sub-mil target. It may actually be at the limit of aiming of the weapon. The actual fine corrections that can be dialed in is what I am speaking about. In technical terms this is called resolution. You actually must have even better resolution to adjust aim after initial aiming. Typically a factor of 10 would be good and a factor 0f 5 maybe acceptable. In addition: US tank gunnery policy for the 75mm ordered HE against tanks at ranges over 2000 meters. I am not so sure this is due to failure to penetrate as much as failure to actually hit the target. Surely a 75mm AP round can destroy many vehicles with a side hit at this range? It is a branch off the discussion but still within cherry tree.

Again, Unless a person understands that there is vertical dispersion and horizontal dispersion, there is no need to discuss accuracy. You are throwing the word accuracy around without recognizing one of the most fundamntal aspects of this discussion. As food for thought (for those that can eat) try to understand this.. An antitank gun is accurate when attacking tanks yet inaccurate when attacking a trench. Tank and trench are both at 500 meters.

Until people here can grasp the difference in vertical dispersion and horizontal dispersion, there is no point about discussing accuracy.

Except you were assuming an exposed turret crew? Could you also explain what this is about? You just finished saying there is no correlation between accuracy and velocity (hah!) and now you want to calculate energy at target? Why? [ July 07, 2005, 04:45 PM: Message edited by: RexMan ]

Poorly placed? Worse than your FlaK contribution?

..and much of that has nothing to do with hitting a vertical target like an antitank gun shield.

And tanks generally do not have the elevation required to use upper register.

Muzzle energy is easily calculated as 1/2*mass*velocity^2. The sherman smoke shell is actually a HE shell filled with some type of smoke producing chemical and a small HE core. The mass is not that much different than a HE shell. You are also incorrect regarding twist and spin. A higher velocity gun does not need an agressive twist to get the same amount of spin. [ July 07, 2005, 03:04 PM: Message edited by: RexMan ]

You are probably confusing accuracy with something else as well as confusing the accuracy of hitting vertical targets vs. horizontal targets. And as far as 'so?'. Can you care to expand on that? Or what you are 'soing' about?

The US 75mm armed shermans did not fire a smoke round with 12% of the muzzle energy (do you mean velocity?) of any AP round they fired. It is not quite the amazing feat that you imagine. I can get the actual muzzle velocities for all the US 75mm rounds if you like.