Stars and Bars

Military aircraft have had insignias applied to the fuselage and wings to identify the nation and branch of service that they are affiliated with. This practice began in 1912 by the French just before World War I.
Here are several US insignias used from 1919 to the present. I recently uploaded a vector (resizeable) version of these designs to my portfolio at iStockphoto.com so if you are interested in a copy go here to obtain one.

Pre War (August 1919- May 1942) Early War (May 1942- June 1943)
Mid War (June 1943- September 1943) Late War (September 1943 January 1947)
Operation Torch (November 1942) To Date (beginning January 1947)
Standard Sizes
Size    Wing Insignia     Fuselage Insignia
1        40″ (101,60cm)     35″ (88,90cm)
2        45″ (114,30cm)     40″ (101,60cm)
3        50″ (127,00cm)     45″ (114,30cm)
4        55″ (139,70cm)     50″ (127,00cm)
5        60″ (152,40cm)     55″ (139,70cm)
6      105″ (266,70cm)     60″ (152,40cm)
Placements
The dimensions of the insignia are based on the diameter of the Blue field. A general rule of thumb for the placement is that the insignia should be the largest size possible but should not exceed 75% of the vertical height of the point of application. On the wings, it normally should be located one-third of the distance from the wing tip to the fuselage.