FX-4 designer/builder, Bill Ferguson, has a total of forty years experience in the aircraft industry. In 1951 he joined the military and graduated from the USAF Technical school as a heavy bomber specialist. He then served as a B-36 technician and worked on the flight line as a C-130 and B-47 technician. From 1959-1990 Bill worked for Delta Air Lines as a certified metallurgy, pre-flight inspector in quality control, and as an inspector in non-destructive testing. During the 30 years Bill spent with Delta he spent hundreds of hours in technical school on commercial aircraft and their related systems.

In his spare time, Bill built airplane kits that he purchased from manufacturers and flew many hours with friends. But he was not satisfied with the design and performance of these airplanes so when he retired from Delta, he, with some suggestions and assistance from a couple of his friends (a Delta engineer, and Rhett Radford, a pilot with experience in aerobatics and small aircraft building) designed an airplane which would meet his standards in safety, design, performance, and appearance. The result was the F-II, an aerodynamically clean, two-place, pusher type aircraft with gull wing doors which flew better than even Bill expected. He only intended to build a special airplane for himself, but when he won "Grand Champion" at the '91 Sun 'N Fun Fly-In at Lakeland, Florida, so many people asked how they could get one of his special planes, Bill decided to manufacture F-II kits.