Nov 1942 : enroute to North Africa invasion beachhead, Wildcats of VF-9 and VF-41 on USS Ranger testing their 50-caliber wing machine guns in open Atlantic ocean. Yellow outline painted on fuselage US national insignia, but no yellow outline painted on upper wing insignias. Although planes lack squadron code and plane numbers, they were in fact censored by US military (to hide deployed squadron identities) with photo being meticulously altered by airbrush which was a major feat for 1940s-era. Based other US naval photo of the same lineup, first three Wildcats from (left to right) assigned to VF-9 squadron : 9-F-20, 9-F-9, 9-F-18. Remaining three Wildcats assigned to VF-41 squadron, but they used only individual plane numbers : 22, 21, 25. U.S. Navy VF 1 - 99 Squadron Insignia - www.bluejacket.com/usn_avi_insig_vf1-99.html

Inset : SBD dive-bomber 41-S-7 of VS-41 scouting squadron flies over Allied invasion fleet for anti-submarine patrol. SBD also sports yellow outline around national insignia. Air Group 4 - Bombing Squadron 4 - VB-4 - http://www.airgroup4.com/bombing.htm

For carrier-based squadrons, yellow outline was quickly removed after the invasion. However, US Army 12th Air Force taking over air combat duties in North African theater continued to use yellow outlines around its national insignia until 1944.

Note during WW2, Air Force came under jurisdiction of US Army, just like Marines were under jurisdiction of US Navy. 1947 postwar defense reorganization separated US military into 4 service branches : 1) Army, 2) Navy, 3) Air Force, 4) Marines. It was also at this time US changed its Department of War to less bellicose and more politically-correct Department of Defense as we know it today. US Army 12th Air Force - www.armyaircorps.us/wwii_12th_Air_Force.cfm