Editing Shrapnel shell (section)

===Technical considerations===
The size of shrapnel balls in World War I was based on two considerations.  One was the premise that a projectile energy of about {{convert|60|ftlbf|J|lk=on}} was required to disable an enemy soldier.<ref>Lt-Col. Ormond M Lissak, [https://archive.org/details/ordnancegunneryt00lissrich Ordnance and Gunnery. A Text-Book. New York: John Wiley, 1915. Page 446]</ref><ref>Treatise on Ammunition, 10th Edition, 1915. War Office, UK. Page 173.</ref> A typical World War I {{convert|3|in|mm|adj=on}} field gun shell at its maximum possible range traveling at a velocity of 250 feet/second, plus the additional velocity from the shrapnel bursting charge (about 150 feet per second), would give individual shrapnel bullets a velocity of 400 feet per second and an energy of 60 foot-pounds (81 [[joule]]s): this was the minimum energy of a single half-inch lead-[[antimony]] ball of approximately {{convert|170|gr}}, or 41–42 balls = 1 pound.<ref group=note>Foot-pounds are calculated as ''wv''<sup>2</sup>/2''gc'', where ''gc'' is the local acceleration of gravity, or 32.16&nbsp;ft/second. Hence for the British calculation: 60&nbsp;foot-pounds =&nbsp;1/41&nbsp;×&nbsp;''v''<sup>2</sup>/64.32 . Hence ''v''<sup>2</sup> =&nbsp;60&nbsp;×&nbsp;64.32&nbsp;×&nbsp;41 . Hence v = 398 feet/second</ref> Hence this was a typical field gun shrapnel bullet size.

The maximum possible range, typically beyond {{convert|7,000|yards}}, was beyond useful shrapnel combat ranges for normal field guns due to loss of accuracy and the fact that at extreme range the projectiles descended relatively steeply and hence the "cone" of bullets covered a relatively small area.

At a more typical combat range of {{convert|3,000|yards}}, giving a fairly flat trajectory and hence a long "[[Field of fire (weaponry)|beaten zone]]" for the bullets, a typical 3-inch or 75-mm field gun shrapnel shell would have a velocity of approximately 900 feet/second. The bursting charge would add a possible 150 feet/second, giving a bullet velocity of 1,050 feet/second. This would give each bullet approximately 418 foot-pounds: seven times the assumed energy required to disable a man.
: <math>1/41 \times 1050^2/64.32 = 418 \text{ foot-pounds}</math>

For larger guns which had lower velocities, correspondingly larger balls were used so that each individual ball carried enough energy to be lethal.

Most engagements using guns in this size range used direct fire at enemy from {{convert|1,500|yards}} to {{convert|3,000|yards}} distant, at which ranges the residual shell velocity was correspondingly higher, as in the table – at least in the earlier stages of World War 1.

[[File:US3inchShrapnelPatterns1915.png|thumb|upright=1.5|left|Trajectory and pattern of US {{convert|3|in|mm|adj=on}} Shrapnel shell of WWI era.]]
The other factor was the trajectory.  The shrapnel bullets were typically lethal for about {{convert|300|yards}} from normal field guns after bursting and over {{convert|400|yards}} from heavy field guns.  To make maximum use of these distances a flat-trajectory and hence high-velocity gun was required. The pattern in Europe was that the armies with higher-velocity guns tended to use heavier bullets because they could afford to have fewer bullets per shell.<ref>Bethel p. 124.</ref>

The important points to note about shrapnel shells and bullets in their final stage of development in World War I are:
*They used the property of carrying power, whereby if two projectiles are fired with the same velocity, then the heavier one goes farther. Bullets packed into a heavier carrier shell went farther than they would individually.
*The shell body itself was not designed to be lethal: its sole function was to transport the bullets close to the target, and it fell to the ground intact after the bullets were released. A battlefield where a shrapnel barrage had been fired was afterwards typically littered with intact empty shell bodies, fuses and central tubes. Troops under a shrapnel barrage would attempt to convey any of these intact fuses they found to their own artillery units, as the time setting on the fuse could be used to calculate the shell's range and hence identify the firing gun's position, allowing it to be targeted in a counter-barrage.
*They depended almost entirely on the shell's velocity for their lethality: there was no lateral explosive effect.

A firsthand description of successful British deployment of shrapnel in a defensive barrage during the [[Third Battle of Ypres]], 1917: <blockquote>... the air is full of yellow spurts of smoke that burst about 30 feet up and shoot towards the earth – just ahead of each of these yellow puffs the earth rises in a lashed-up cloud – shrapnel – and how beautifully placed – long sweeps of it fly along that slope lashing up a good 200 yards of earth at each burst.<ref>Lieutenant Cyril Lawrence, 1st Field Company, Australian Engineers. Quoted in "Passchendaele. The Sacrificial Ground" by Nigel Steel and Peter Hart, published by Cassell Military Paperbacks, London, 2001, page 232. {{ISBN|978-0-304-35975-2}}</ref></blockquote>