Just to clear up this little debate, I went in and looked this up. I knew I seen it somewhere before, I just couldnt remember exactly where. Maybe its just a military thing or even just an Air Force thing (since this is quoted out of an Air Force document), but according to AFPAM 36-2241 section 8.2.4.3.12, the union should be facing forward. Think about it like this: If you attached a flag pole to your vehicle, the union is at the top, closest to the pole. When driving forward, the stripes would trail behind. This is by no means meant to call anyone out or say "Your wrong, you need to change it." Im just posting this as a little FYI. When serving in the military, you kinda have a different appreciation for the flag. Im sure anyone who was/is in knows where Im coming from. Again, Im not trying to make anyone sound dumb or say your wrong. This is definietly the best graphics Ive seen on a raptor and will be looking into doing this myself.
That is the longest multi quote I have ever seen. Lol.
I would say it's a general military custom or tradition but the Air Force had nothing better to do so they put it in an instruction.