12/29/2014. Remarks by Matthew Long: "Designed and based on research by Professor Otto Koppen of the Massachusetts Institute of Technology (MIT), the lone Puritan 50 (1939) became the prototype for the very similar General Aircraft Corp. G-1-80 Skyfarer (1942) produced in small numbers. Both used two-axis controls and H-tail twin rudders for stall- and spin-proof operation, placarded as such in the cockpit. Professor Koppen's research also influenced Fred Weick in the design of the better-known and widely-produced ERCO Ercoupe series."