I remember watching an old bloke prepping up his plane to fly it at our local oval when you could still do things like this, before the Fun Police legislated everything out of the bounds of Joy. It was a Catalina Flying Boat, with a wingspan of about 8 feet!! Had 4 6cc motors and prop diameters of around 12 inches! It was massive. I waited for well over an hour while he tinkered with it, but never got to see it in the air. I always regretted not hanging around long enough to see it fly, but I was due at a sports event.