The FLUGWAG Bremen ESS 641 was a 1970s German glider-towing monoplane designed and built by the Flugwissenschaftliche Arbeitsgemeinschaft Bremen research organisation.
The ESS 641 is a low-wing cantilever monoplane with a fixed tail-wheel landing gear. Powered by a Avco Lycoming O-360 flat-four piston engine. The pilot had an enclosed cockpit with a transparent canopy.