Ray,
Been there, done that. However, luckily for me my eight year old was articulate enough to explain to all concerned about WWI, biplanes, triplanes, the Red Baron, etc. at the time. When he was a baby he'd sit in my lap on days I was Mr. Mom and play Red Baron with me on the PC. I created a monster. When he was six my wife was repainting his bedroom and asked him if he'd like something painted on the walls. She was thinking it'd be animals, or planes in general, etc.
Nope.
He said, and I quote: "I want a SPAD coming onto an observation balloon for a sausage roast, and a Fokker coming up under him to get him!" SWMBO then had me explain what he meant. Long story short, I photocopied some kit box art, she blew them up and traced them on to the wall, and painted exactly that for him. Said son is in his mid-20's living in that old place now with his new bride. He said when he moves out, he's going to take a saw and cut out that part of the wall and frame it.
Apologies for the thread drift.
WD