R-6 was a direct descendent of the R-4. The R-5 and R-6 were derived under contract
to the U.S. Army following the successes of the VS-300. During World War II, more
than 200 R-6s were delivered to the U.S. Army for military operations including
aerial observation. The R-6A was called the Hoverfly and it could be fitted with
floats or wheels.