The style of Balkenkreuz used by the Third Reich's Luftwaffe on the lower surfaces of aircraft wings and on the fuselage sides, drawn with the official proportions specified by the Reich Air Ministry just before the outbreak of World War II in 1939.  Such dimensions were also the basis of the "low-visibility" version of this marking used late in World War II by the Luftwaffe, using only the "flanks" of the marking shown in white for this regulation example. German armored fighting vehicles (AFVs) during the invasion of Poland (September-October 1939) used a plain white cross, but before the onset of Operation Weserübung (April 1940), the black core cross with white "flanks" that the Luftwaffe used had become the basic German AFV national insignia, as used for the rest of the war (to 1945).
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CC BY-SA 3.0
own, from <a rel="nofollow" class="external text" href="http://www.luftarchiv.de/index.htm?/flugzeugbau/kenungen.htm">original German specifications found online (<i>Abb.4</i> illustration at linked page)</a>, initially drawn in DesignCAD, then ported to PNG format in CorelDRAW