While drudging our luggage through TSA and slowly boarding a cramped metal tube along with hundreds of other annoying people, we often forget the engineering marvels that are modern jetliners. Recent Boeing issues aside, modern planes are staggeringly safe and reliable, but they weren't always that way. 

Planes have engineered themselves into pretty recognizable shapes, and it can be hard for anyone other than a staunch aviation enthusiast to tell the difference between a Boeing 737 or an Airbus A320. But back in the olden days, people were still figuring out what worked best, and that resulted in some pretty wacky flying shapes. This gallery shows just a few of those early aviation concepts, up through the aircraft of World War II, when necessity meant planes finally started to get the mass use and engineering they get today.