Number 2: Boeing 737, Nickname: Guppy
The Boeing 737 has definitely grown over the years. When it first flew, it was designed to fly regional routes that were too small for the larger Boeing 727 to fly. Over time, the 737 grew from the short -100 to the slightly longer -200. Then in the early 80’s the jet grew again and added high bypass CFM56 engines. Now known as the classic, the -300s, -400s, and -500s powered many major airlines from the 80s all the way through the first decade of the 21st century. Then came the NGs or Next Generation with the -600, -700, -800, -900. And for better or worse, today we have the MAX -7, -8, -9, with the -10 variant coming soon.
So why is the 737 called a Guppy? Back in the day though, the “Baby Boeing” looked more like a baby fish. Short in length, a bit chubby, highly adaptable, and not overly fast. The nickname was popular for a while but now that some 737s can carry as many people as a 757, the guppy has grown up quite a bit.