Basic rules of the road. P-47 was over taking the Spit. If you're passing another aircraft, you have to ensure adequate separation. Same thing with real aircraft, boats, cars, etc. Spit was straight and level from what I saw, and if I were the pilot of the Spit, I'd be pissed. The club's separation of flight line/pits/spectator area, pretty much non-existent as well. Hopefully an incident like this is one we'll never have to deal with.