I’m always looking for reference. Today I was seeking out 2d drawings of WWII aircraft and I came upon this little gem on the web.
http://bagera3005.deviantart.com/gallery/4261057
Look through this guy’s gallery. Tons of schematics for all kinds of things. A very thorough weapon schematic gallery, tons of aircraft, Iron Man and sci fi schematics. You name it, this guy has it…with the exception of cars.