Doflug D.3801 The Doflug D.3801 was a development of the Doflug D.3800, a Swiss produced licenced version of the Morane-Saulnier M.S.406. Powered with a licensed-produced HS-51 12Y engine, it retained the other improvements incorporated in the D.3800 and introduced a fixed radiator. A total of 207 were produced, with a further 17 completed from spares.