Developed in parallel with the R-37, the R-38 was essentially similar to the R-36 apart from having a 1030hp Rolls-Royce Merlin II engine. It was originally proposed with wings of two different sizes, but the sole prototype retained a similar wing to that of the R-36 and R-37. Armament comprised four wing-mounted 7.7mm or 13.2mm machine guns. The R-38 flew for the first time on 4 August 1939, and gave excellent results during its test programme, which was still in process when German forces occupied Belgium. The sole prototype was flown to Bordeaux when the final collapse of Belgian resistance became inevitable, but was scrapped after capture in France by German forces.