Flak jacket

The term "flak jacket" is often colloquially applied to newer body armor featuring protection against small arms projectiles, but the original usage predated the existence of modern and more resistant bulletproof vests and the two are not interchangeable in performance.

Anecdotes describing garments designed to protect the wearer from penetrating weapons can be found far back into recorded history.

For example, soft armor made of silk was tried on a small scale based on Japanese designs, but this material did not last well under harsh environmental conditions.

[1] The first usage of the term "flak jacket" refers to the armor originally developed by the Wilkinson Sword company during World War II to help protect Royal Air Force (RAF) aircrew from the flying debris and shell fragments thrown by German anti-aircraft guns' high-explosive shells (flak itself is an abbreviation for the German word "Fliegerabwehrkanone" (aircraft-defense gun)).

[4] During World War II, flak jackets and steel helmets were worn by US Navy personnel on aircraft carriers during battle, since the ships and especially their flight decks offered little protection for their crew.

Col. Grow’s request to the Wilkinson Sword company was to develop a vest that could stop a .45 caliber (11.43 mm) round fired at close range.

[2] Although flak jackets offered protection against some small caliber pistol bullets and shell fragments,[5] ultimately they proved to be less effective than hoped.

Nevertheless the Army's and Marine's Flak vests did a good job of stopping mortar shells, debris, grenade fragments, ricochets, and direct hits from mild-power pistol rounds.

[6] The first flak jackets consisted of manganese steel plates sewn into a waistcoat made of cotton canvas, with later revisions of the vest, the waistcoat was made of ballistic nylon (a material engineered by the DuPont company); therefore, flak jackets functioned as an evolved form of plate armor or brigandine.