sentences:  The third prototype (V3) was constructed as a seaplane with twin floats.This was tested at the "Erprobungsstelle Travemünde" military seaplane test facility on the Baltic coast, and was scrapped in 1942 at Heinkel's factory airfield in the estuarine "Rostock-Schmarl" community, then known as Marienehe.On 22 November 1937, the fourth prototype (V4) made a world class-record flight in which it recorded an airspeed of 505 km/h (314 mph), with a payload of 1,000 kg (2,205 lb), over a distance of 1,000 km (621 mi).