Heinkel HeS 8

Heinkel Strahltriebwerke

Company type	Division / Subsidiary
Industry	Aerospace, Jet engine manufacturing
Founded	1930s
Founder	Hans von Ohain
Headquarters	Germany
Products	Jet engines (HeS 8, HeS 30, HeS 011)

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The Heinkel HeS 8 (short for "Heinkel Strahltriebwerke 8" – meaning Heinkel Jet Engine 8) was an early jet propulsion engine conceptualized by Hans von Ohain during his tenure at Heinkel. It holds the distinction of being the initial jet engine project to receive financial endorsement from the RLM, officially designated as 109-001. Had development continued uninterrupted, it likely would have been renamed the Heinkel 001, although this designation appears not to have been applied in practice.

Designed primarily to power the twin-engine Heinkel He 280 fighter aircraft, the HeS 8 was ultimately less favored by both Heinkel and von Ohain compared to the axial compressor-based HeS 30. Its extended development timeline meant it reached production readiness approximately concurrently with the Junkers Jumo 004 and BMW 003 engines. By 1942, work on both the HeS 8 and HeS 30 ceased, with Heinkel directed to focus on the larger-scale Heinkel HeS 011. Consequently, the He 280 fighter remained without an operational engine and was eventually discontinued.

Design and development

As the HeS 3 project concluded in 1939, von Ohain's preference shifted away from the centrifugal compressor for jet propulsion. Although he had become convinced of the axial compressor's advantages as early as 1938 following discussions with D. Encke from AVA, he persisted with centrifugal designs in the HeS 3 due to their relative ease of manufacture. It is probable that an axial compressor design would have succeeded the HeS 3 if not for the RLM's interest in maintaining von Ohain’s work on centrifugal compressors as a contingency should axial concepts encounter difficulties.

A significant limitation of centrifugal compressors was their large frontal area. Von Ohain began exploring solutions to this issue as early as 1937 during the final stages of the HeS 1 design. His initial approach with the HeS 3 involved separating the compressor and turbine—which had been arranged back-to-back in the HeS 1—and placing combustion chambers between them. Although challenges with this initial configuration led to a revised HeS 3b layout, von Ohain considered this arrangement optimal and revisited it in developing the HeS 8. This resulted in an engine only marginally wider than its compressor disk, contrasting with earlier designs where external piping increased overall dimensions.

Another challenge faced by earlier engines was their sensitivity to irregularities in intake airflow. To mitigate this, the HeS 8 incorporated a low-pressure impeller ahead of the main compressor within the intake duct. While this impeller contributed minimally to compression, it effectively stabilized airflow by elevating pressure at the compressor face. Both the impeller, featuring 14 blades, and the main compressor with its 19 blades were crafted from milled aluminum. The turbine consisted of a steel, uncooled component with 14 blades—implying frequent turbine burnout risk. All rotating parts were mounted on a shared tubular power shaft supported by three ball bearings. The combustion chamber employed two diffusers to decelerate airflow exiting the compressor before fuel injection through 128 nozzles arranged in two staggered rows. Supporting systems such as the starter were clustered around the intake area without increasing engine diameter.

Progress was gradual; when the first prototype of the He 280 became available in September 1940, its engine was not yet flight-ready. Initial tests involved glider trials while engine refinement and additional airframe construction proceeded. By early 1941, engines reached operational status but delivered only about 500 kg of thrust instead of the targeted 700 kg. Once installed, the He 280 conducted its maiden flight on April 2, 1941, though engine cowling had to be omitted due to fuel leakage issues. Three days later, a demonstration flight before RLM officials garnered positive impressions, resulting in full endorsement of Heinkel’s jet program.

Cancellation

Progress on the engine's development halted around this stage, with thrust reaching merely 550 kg by early 1942. To enhance performance, a single axial compressor stage was introduced after the centrifugal compressor starting from the V15 prototype, while revised airflow management within the compressor was implemented from V16 onward. Approximately 30 units were completed in total, with the later variants incorporating these upgrades achieving roughly 600 kg of thrust. However, by then, several all-axial compressor designs—including Heinkel's own HeS 30—were advancing well. Helmut Schelp, overseeing jet engine development at the RLM, deemed the BMW 003 and Junkers Jumo 004 sufficiently effective and consequently terminated all ongoing work on Heinkel’s existing models. He instead directed their efforts toward creating a "Class II" engine targeting about 1,300 kg of thrust, which ultimately developed into the Heinkel HeS 011.

Variants

Throughout the project, multiple adaptations of the original HeS 8 configuration were investigated. The HeS 9 seems to have involved adding a second axial compressor stage and substituting the entire centrifugal stage with a new "diagonal compressor," a design favored by Schelp. Although details remain scarce, it is known that the RLM placed an order for ten units of this variant; however, none were constructed. This configuration likely served as a foundation for the subsequent development of the 011. Another variant, designated HeS 10, incorporated a complete HeS 8 engine within an enlarged casing and featured an intake impeller larger than the core engine itself. The HeS 10 is considered an early example of what would now be classified as a turbofan engine. To harness additional energy from the exhaust gases to drive the fan, an extra single-stage axial turbine was added behind the existing centrifugal turbine of the HeS 8. The primary distinction between the HeS 10 and contemporary turbofan engines was that its fan was not independently powered from the core; nonetheless, given the separate axial turbine stage, implementing such independence would have been feasible.

External links

• Spanish resource featuring detailed information on the HeS 8 engine