Tiger Use of Battlesight Aim

[rexford]

Roughly about a year ago plus some months there was a discussion about how the Germans taught battlesight aim, which theoretically would result in a 100% hit probability from 0m to 950m against a 2m high target (level ground).

At the time I offered some analysis which supposedly showed that the Tiger Fibel was incorrect, and that having the main gun above the target bottom would reduce hit chances.

During a recent discussion on another web site regarding battlesight aim, I realized that my previous work and conclusions regarding battlesight aim forgot to change the angle from gun height to hull bottom as actual target range varied. I had used the 950m angle from gun to hull bottom at all target ranges, which suggested that the Tiger Fibel was incorrect.

Turns out I was incorrect. The trajectory height and shape are roughly the same whether the Tiger gun is 1.64m above T34 hull bottom, or at the same elevation as Tiger Fibel appears to assume.

Battlesight aim by a Tiger, as described in the Tiger Fibel, is when an aim range is computed where the trajectory will never exceed 2m above target hull bottom on level ground. A Tiger using a 950m battlesight aim would theoretically hit any 2m or taller target (measured from hull bottom) at all ranges up to 950m.

When Tiger uses a 950m battlesight aim against a target at 500m, the gun is initially aimed straight at the hull bottom. This results in a downward angle of arc tangent (-1.64m/500m), or -0.19°. The gun is then elevated to the 950m range graticule on the scope, which adds +0.49° for a resultant elevation angle of 0.30° above horizon.

My previous calculations used the 950m angle from Tiger gun to T34 hull bottom, which was -.10°, so the gun angle was overestimated at 0.39°. This overestimated trajectory height above target hull bottom.

When I redid the calculations using the correct approach, the trajectory elevations above hull bottom with Tiger gun at same elevation as the T34 hull bottom were about the same as when the gun was 1.64m above the target bottom aim. So Tiger Fibel is correct! Gun location does not appear to matter with battlesight aim.

Here are the trajectory heights and resultant accuracies from the correct analysis when Tiger uses 950m battlesight aim against a T34 on level ground (based on a simple physics approach that roughly approximates all figures):

Target Range--Trajectory Height-Hit Probability

200m----------1.30m------100%

300m----------1.74m-------93%

400m----------1.96m-------56%

500m----------2.00m-------50%

600m----------1.85m-------66%

700m----------1.60m-------84%

800m----------1.03m-------98%

900m----------0.50m-------84%

950m----------0.00m-------50%

Trajectory height is above hull bottom, and all calculations used a simple physics approach instead of detailed ballistics, so the results are very approximate. 2m target height is assumed from hull bottom to turret top, with infinite width.

The hit probability is not 100% when the trajectory places rounds on the target since random scatter has been considered. At 700m, 68% of vertical dispersion is within 0.41m of the average trajectory height. When the average trajectory is 1.60m above hull bottom, distance from average trajectory to 2m high target top is 0.40m and 32% of the upward scatter passes over the target. None of the low scatter misses the target (assume infinite width to simplify the math).

So the resultant hit probability at 700m is 84%.

Tiger use of battlesight aim against targets at 0m to 950m will always place the average trajectory on the target assuming level ground, but random scatter will vary the hit probability from 50% to 100%.

While battlesight aim appears to boost the hit probability against targets at 700m to 900m range, the hit percentages at 400m to 600m appear to be much lower than would be attained with center of mass aim and visual range estimation (Tiger crews were expected to estimate range within 10%, much better than the 25% figure associated with the average commanders visual estimate).

Combat reports do not suggest that battlesight aim was always used by German tanks, and German tankers and ATG crews were often trained to aim at the intersection of turret and hull. Turret ring was very vulnerable, and it was said that 37mm PaK rounds could significantly damage a KV tank with turret ring hits: this may have lead to the use of added hull side plates to protect the KV-I turret ring area.

It is not clear if American tankers during WW II were trained to use battlesight aim, none of the my U.S. tank crew manuals for WW II offer a first shot alternative to center of mass fire.

Details presented for the few who are interested, others will get the gist by scanning the paragraphs and hopefully will not be sleeping when they get to this paragraph.

Good night.

[ November 26, 2002, 09:37 PM: Message edited by: rexford ]