Dragon
Dragon's vertical loops look very conventional, but it took a while for this coaster's manufacturer to figure out how to build roller coaster loops.  Their first looping coaster was built five years before this one, and it also had two vertical loops.  Its inversions not only had a different design, they had to be greatly modified after construction in order to get the trains to pass through them.  This view of the Texas Tornado at Wonderland Amusement Park in Amarillo, Texas shows the strange loops and how they were changed.

©2020 Joel A. Rogers.