Hi thunder,
I would think that like cars, It would look greyish. I have seen pics of night fighters from WWII and they used a grey wash but very light. One thing to remeber though is that most moderen military jets would not be allowed to get to the point of looking that way. The only people more anal about those jets no matter what country than the pilots is the flight crews for each bird. Take a look at an SR71, U2 , B2 or F117. Those are the most recent all black air craft around. Some of the B 52s were also painted black. Your best bet is to just go to a search engine and look for pictures. I hope this info helps and look foward to seeing some pics of the finished project. Email me if you need any help bfesta@bellsouth.net
Happy modeling
Brian