The Heinkel He 100 was a German pre-World War II fighter aircraft design from Heinkel. Although it proved to be one of the fastest fighter aircraft in the world at the time of its development, the design was not ordered into series production, Approximately 19 prototypes and pre-production machines were built. The reason for the failure of the He 100 to reach production status is subject to debate. None are known to have survived the war.
Officially, the Luftwaffe rejected the He 100 to concentrate single seat fighter development on the Messerschmitt Bf 109. Following the adoption of the Bf 109 and Bf 110 as the Luftwaffe's standard fighter types, the RLM announced a "rationalization" policy that placed fighter development at Messerschmitt and bomber development at Heinkel.
Because there are no surviving examples and since many factory documents, including all blueprints for the He 100, were destroyed during a bombing raid, there is limited specific information about the design and its unique systems.
Following the selection by the RLM of the Bf 109 as its next single seat fighter over the Heinkel He-112, Ernst Heinkel became interested in a new fighter that would leap beyond the performance of the Bf 109 as much as the Bf 109 had over the biplanes it replaced. Other German designers had similar ambitions, including Kurt Tank at Focke-Wulf. There was never an official project on the part of the RLM, but Rudolf Lucht felt that new designs were important enough to fund the projects from both companies to provide "super-pursuit" designs for evaluation. This would result in the single-engined He 100 fighter, and the promising twin-engined Fw 187 Falke
Zerstörer style heavy fighter, both reaching the flight stage of development.
The super-pursuit type was not a secret, but Ernst Heinkel preferred to work in private and publicly display his products only after they were developed sufficiently to make a stunning first impression. As an example of this, the mock-up for the extremely modern-looking He 100 was the subject of company Memo No.3657 31 January that stated: The mock-up is to be completed by us... as of the beginning of May... and be ready to present to the RLM... and prior to that no one at the RLM is to know of the existence of the mock-up. Walter Günter, one half of the famous Günter brothers, looked at the existing He 112, which had already been heavily revised into the He-112b version and decided to start over with a completely new design, Projekt 1035. Learning from past mistakes on the 112 project, the design was to be as easy to build as possible yet 700 km/h (435 mph) was a design goal. To ease production, the new design had considerably fewer parts than the 112 and those that remained contained fewer compound curves. In comparison, the 112 had 2,885 parts and 26,864 rivets while the P.1035 was made of 969 unique parts with 11,543 rivets. The new straight edged wing was a source of much of the savings; after building the first wings, Otto Butter reported that the reduction in complexity and rivet count (along with the Butter brothers' own explosive rivet system) saved an astonishing 1150 man hours per wing.
Walter was killed in a car accident on 25 May 1937, and the design work was taken over by his twin brother Siegfried, who finished the final draft of the design later that year. Heinrich Hertel, a specialist an aircraft structures, also played a prominent role in the design. At the end of October the design was submitted to the RLM, complete with details on prototypes, delivery dates and prices for three aircraft delivered to the Rechlin test center. At this point the aircraft was referred to as the He 113, but the "13" in the name was apparently enough to prompt Ernst Heinkel to ask for it to be changed to the He 100. It is reported Ernst Heinkel lobbied for this "round" number in hopes it would improve the design's chances for production.