“The flag should not be draped over the hood, top, sides, or back of a vehicle or of a railroad train or a boat.  When the flag is displayed on a motorcar, the staff shall be fixed firmly to the chassis or clamped to the right fender." (U.S. Code, Title 4, Chapter 1, Section 7(b))

"When displayed either horizontally or vertically against a wall, the union should be uppermost and  to the flag's own right, that is, to the observer's left. When displayed in a window, the flag should be displayed in the same way, with the union or blue field to the left of the observer in the street."(U.S. Code, Title 4, Chapter 1, Section 7(i))

"No part of the flag should ever be used as a costume or athletic uniform.  However, a flag patch may be affixed to the uniform of military personnel, firemen, policemen, and members of patriotic organizations.  The flag represents a living country and is itself considered a living thing.  Therefore, the lapel flag pin being a replica, should be worn on the left lapel near the heart."  (U.S. Code, Title 4, Chapter 1, Section 8(j))

These citations would lead us to believe that a flag decal or painting on a vehicle or a flag patch should always have the union of the flag to the viewer's left.  This works well when looking at the left side of the vehicle or person.   When looking at the right side however, if the union is to the viewer's left, it appears as though the flag is flying backwards when the vehicle or person is in motion.   It would also place the flag in a position of being in retreat as the vehicle or person moves forward.

To alleviate this problem, the International Civil Aviation organization decreed that flags painted on aircraft must face the direction of the flight, so as to be aerodynamically and aesthetically correct.  We also recommend that  flags or flag decals on vehicles and flag patches on uniforms should be so oriented.

Thus we recommend that the flag patch on the left sleeve of a uniform should have the union to the viewer's left while a patch on the right sleeve should be displayed with the union to the viewer's right so that, in both cases, the flag is facing forward and is streaming to the back as the person moves forward.

The decals or paintings on a vehicle would also be placed so that the union on the driver's side of the vehicle would be to the viewer's left while the union on the passenger side of the vehicle would be to the viewer's right.