Deciding that a primary trainer for the CPTP (Civilian Pilot Training Program) program was the most logical way to go for a small company like Interstate Engrg. Corp. to enter the aviation business. It would also make better use of the available floor space in their plant in El Segundo, Calif., a suburb of L.A.  The company engaged a highly respected aeronautical engineer, Ted Woolsey, to do the designing and engineering.  After he laid out the basic design it became sort of a school project because most of the work was handled by students from Wiggins Trade School.  There was nothing outstanding about the new airplane except that it was designed to be an improvement over other airplanes of its type.  The S-1 first flew on April 20, 1940.


The first production came off the line by December 21, 1940, and there were 20 planes right behind it; 120 planes were already in sub-assembly; material for 200 more was already in stock with orders pouring in.  Production of the Cadet for civil use ceased in 1942, but by then “Interstate” had started production of the L-6 liaison version for the USAAF.


The Cadet was a light high–winged cabin monoplane with ample seating for two in tandem.  This plane was not blessed with many soft curves and it gave off the appearance of being somewhat stark and unfriendly, but it was not. The interior was pleasantly arranged, handsomely trimmed, and the ease of operation was the keynote to its character. The S-1-A was powered 85 hp Franklin 4AC-199-D2 engine that provided a cruising speed of 108 mph and range of 320 miles.

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