IT is reported that Herr Dieterle, flying a German Heinkel aeroplane fitted with a Mercedes-Benz engine, has set up a new speed record of 463–8 miles an hour over a three kilometre course. This does not rank as an ofHcial record until it has been examined and homologated by the Fédération Aéronautique Internationale; but there is no reason to doubt that this formal recognition will be given in due course. This has beaten three world records at the same time: the 3 km. of 380 m.p.h. held by Wurster (Germany), the 100 km. of 394 m.p.h. held by Udet (Germany), and the absolute speed record of 440–7 m.p.h. held by Agello (Italy). No certain details of the aircraft are known, but it was probably developed from the Heinkel Hell used by Udet for the 100 km. record in June 1938. Statements that have appeared in non-technical reports that the machine was a single seater fighter fitted with an engine of 1,175 horse-power are obviously misleading. Any machine of this class must have been very thoroughly ‘cleaned up’ in design for such speeds, and even with such alterations the engine must have been both speeded and boosted up to a power of well over 2,000 b.h.p.