[3]: 162–163  Widening either the Speedster or Sportster was considered,[4] but by the time the design was completed, the strut geometry, landing gear, fuselage structure, engine installation, and cabin had to be changed.

[3]: 164–165 Pan American Airways founder Juan Trippe, who personally owned a Rearwin Sportster, approached the company in 1941 to develop an instrument trainer.

[3]: 173–175 The Cloudster was a two- or three-seat aircraft of high-wing design and conventional landing gear arrangement.

The 8135T included fittings for a blackout curtain surrounding the student for instrument training, while allowing the instructor to maintain normal visibility.

The aircraft remained in service as of 1945, with a .30 caliber machine gun mounted on the left wing strut outside the propeller arc.