The Four Star 40 was designed by Bruce. He then did the 120. Then left Sig to do his own stuff. He brought out the Venture 60 which he claims to be a improvement over the Four Star.

I think Claude McCulloch designed the Four Star 60? Cannot remember? The 60 was the last of the three to come out. The proportions of the 60 are a little different than the 40 or 120.

There were some planes that preceeded the Four Star 40 that led up to the idea to bring it out.

There was the Ace 4-40 or something like that which was more or less like the Sig Mid Star. Then there was the Ace Bingo 60 and Big Bingo 120. These planes reminds one very much of the Sig Four Star series. These planes had more of a Doc Mathews origin. The airfoils were thinner and less symetrical than on the Sig planes. Balsa USA brought out planes like these 10 years or so ago. They have since dropped by the wayside.