Heinkel He 176

Heinkel

Industry	Aerospace
Founded	1922
Founder	Ernst Heinkel
Headquarters	Rostock , Germany
Products	Aircraft, including experimental rocket-powered aircraft such as the He 176

The Heinkel He 176 was a German experimental aircraft powered exclusively by a liquid-fueled rocket engine. Marking a significant milestone, it became the first plane worldwide to achieve powered flight using solely liquid-propellant rocket technology, piloted by Erich Warsitz on 20 June 1939.

Conceived as a private initiative by the Heinkel firm, this project aligned with director Ernst Heinkel's focus on advancing technologies for high-speed aviation. Development began in 1936 following promising rocket propulsion trials conducted on modified versions of the He 72 and two He 112 aircraft. Unlike adaptations of piston-driven models, the He 176 was designed from the ground up specifically to exploit rocket propulsion. Constructed predominantly from wood, the aircraft featured a relatively straightforward and compact structure. It introduced innovative elements such as a pilot seat positioned in a reclined posture and an emergency escape system involving a detachable nose section. The designation He 176 was officially assigned in December 1937.

The project was terminated on 12 September 1939, reportedly due to its limited size and underwhelming performance metrics. Nevertheless, the He 176 validated the concept of rocket-powered flight and contributed valuable insights for subsequent designs like the Heinkel He 280 jet fighter prototype and the Messerschmitt Me 163 rocket interceptor. By war’s end, both the prototype and most related documentation had been destroyed; however, Warsitz suggested that some materials might reside within Soviet or Russian archives. Performance figures commonly cited—such as speeds reaching 750 km/h or 800 km/h—originate from Warsitz’s personal accounts and lack solid documentary support. Only two authentic photographs of the He 176 are known to exist, likely taken during testing at Peenemünde.

Historical context

File:Opel RAK1 2.jpg

Opel RAK.1, recognized as the first publicly flown rocket-powered aircraft on September 30, 1929, piloted by Fritz von Opel

Throughout the 1920s, German innovators and stunt performers experimented with solid-fuel rockets to propel various vehicles including automobiles, motorcycles, railcars, sleds, and eventually airplanes such as Alexander Lippisch’s Ente and Fritz von Opel’s RAK.1 by 1929. However, solid-fuel rockets presented significant drawbacks for aviation applications due to their inability to modulate thrust or shut down engines while fuel remained.

In the mid-1930s, Wernher von Braun and his rocketry team at Peenemünde explored liquid-fueled rocket propulsion for aircraft use. Aircraft designer Ernst Heinkel became an avid backer of these efforts, initially providing a He 72 and subsequently two He 112 planes for experimentation. By early 1937, one such plane had demonstrated flight powered solely by its rocket engine after shutting down its piston motor mid-flight. Concurrently, Hellmuth Walter’s research into hydrogen peroxide monopropellant rockets yielded lightweight and relatively simple propulsion units suitable for aircraft installation—albeit with inherent risks and limited operational duration.

The experimental flights using the He 112 attracted close scrutiny from the Reichsluftfahrtministerium (RLM), which recognized the potential of rocket-powered interceptors. Consequently, Heinkel established a covert division at its Rostock plant to advance this technology beginning in 1936. Departing from previous conversions like the He 112, this team aimed to create an aircraft explicitly engineered around rocket propulsion to maximize performance—resulting in the development of the He 176.

Design

The initial concept for the He 176 was developed during rocket motor and booster trials conducted at Neuhardenberg. In 1936, the RLM granted Heinkel the contract to create the first-ever rocket-powered aircraft. The design was custom-tailored to fit the test pilot Erich Warsitz precisely, resulting in a minimized cockpit size and an overall lightweight airframe. The cockpit was so confined that Warsitz could not bend his elbows, and certain controls were positioned awkwardly. Because the He 176 was intended to operate across a broad speed range, the sensitivity of these controls required multiple adjustments during flight to ensure adequate handling. To aid the pilot in managing high acceleration forces, the cockpit featured an unusual reclined seating posture, which also helped reduce frontal drag and improve aerodynamic efficiency. Entry into the aircraft was facilitated by a rudimentary removable Plexiglas canopy section.

The aircraft was relatively small and, in some aspects, straightforward in construction, predominantly utilizing wood. However, it incorporated a sophisticated fully enclosed cockpit with a frameless, single-piece transparent nose section. The landing gear combined elements of both conventional and tricycle gear configurations: the main gear struts retracted rearward into the fuselage while the aerodynamically faired nose wheel remained fixed. The maximum fuselage diameter measured only 700 millimetres (28 in). The total surface area, including the fuselage, was 5 square metres (54 sq ft), with a wingspan of 5 metres (16 ft), fuselage length of 5.5 metres (18 ft), height with landing gear extended at 1.44 metres (4.7 ft), and a wheelbase of 700 millimetres (28 in). At low speeds, the rudder effectiveness was limited; thus, during takeoff runs, steering was more effectively managed through differential braking.

The He 176’s wings were elliptical with a sweep angle of 40% and a thickness ratio of 9% at 90 millimetres (3.5 in). A slight positive dihedral angle was incorporated to maintain stability. Fuel tanks were housed within the wings' interior, necessitating development of a novel welding method for their manufacture. Considerable effort went into minimizing aerodynamic drag throughout the design. During ground testing, it was observed that wingtips frequently contacted the surface; to prevent damage, metal bumpers were installed on the wingtips.

The design team anticipated that conventional emergency egress by bailing out would be extremely hazardous or impossible at high velocities. As a result, the He 176 incorporated an innovative jettisonable nose escape mechanism. This system used compressed air to detach the nose section from the fuselage, followed by deployment of a drogue chute to reduce separation forces. Afterward, the flush-mounted cockpit canopy would release, allowing the pilot to exit safely. Unmanned scale models of this nose section were successfully tested in flight from a Heinkel He 111 bomber.

Originally, the He 176 was designed around one of the new Walter rocket engines. This engine resembled that used in the He 112 but delivered twice the thrust output—approximately 6,000 Newtons—primarily achieved by adding a pump to draw propellant instead of relying on compressed air for fuel delivery. The propellant consisted of an 82% concentration of hydrogen peroxide. To enhance directional control at lower speeds, it was planned to integrate a rudder within the engine nozzle itself. By July 1937, detailed design work had been completed and construction of the prototype began shortly thereafter. The designation He 176 was formally assigned to this aircraft in December 1937.

Flight Trials and Program Termination

On 20 June 1939, the He 176 completed its first flight, with pilot Warsitz at the controls, marking the world's inaugural manned rocket-powered flight. Warsitz later recounted the experience: "The aircraft took off on a heading quite different from the planned course, lifting off with noticeable yaw and wobble. I maintained a low altitude while accelerating, then gradually pulled back on the stick to climb swiftly. Reaching speeds of 750 km/h, the plane ascended sharply at an angle between vertical and 45°, with extremely sensitive controls. Fortunately, everything proceeded smoothly, and I flew silently around Usedom Island's northern tip at 800 km/h. Executing a sharp left bank to line up for landing, I shed speed and altitude, but during this steep turn the rocket engine cut out as fuel was depleted. The sudden deceleration threw me forward against the harness. Pushing the stick forward, I glided swiftly over Penne and touched down at 500 km/h, crossing the airfield boundary and coming to rest after several small bounces."

After this maiden flight, modifications were implemented; notably, the fixed nose wheel was removed as the design team opted to rely solely on the two main landing wheels and tail skid for routine landings. Subsequent flight tests were conducted before Heinkel presented the He 176 to the Reichsluftfahrtministerium (RLM), which exhibited minimal official enthusiasm. Warsitz noted regarding Von Braun's involvement during trials at Pennemunde: "Though not officially part of the He 176-V1 project utilizing Walter's rocket engine, everything related attracted interest from Von Braun and his team because the He 176-V2 was planned to incorporate Von Braun’s propulsion system."

The lack of support from the RLM significantly influenced Heinkel’s decision to scale back his rocket propulsion initiatives. On 12 September 1939, formal orders were issued to terminate the He 176 test program, apparently due to dissatisfaction with its dimensions and performance characteristics. Only a single unit was ever built; following its retirement from flight testing, it was displayed statically at Berlin’s Air Museum until it was destroyed during an Allied bombing raid in 1943.

Legacy

Prior to program cancellation, Heinkel had been developing a more advanced rocket aircraft often referred to as He 176 V2, which was intended for operational deployment. This variant was designed to be powered by a more potent Von Braun engine capable of reaching speeds up to 1,000 km/h (620 mph). Although no prototype of this model was ever constructed, confusion arises because it shares its designation with the flown aircraft—leading many publications and websites to mistakenly illustrate this design when referencing the original He 176.

Technical insights gained from the He 176 project contributed to subsequent Heinkel developments, including their jet fighter prototype, the He 280.

Germany eventually fielded an operational rocket-powered fighter—the Messerschmitt Me 163 Komet, designed by Alexander Lippisch but produced by Messerschmitt. By the time orders came to halt work on the He 176, initial efforts on the Me 163 were already underway. This aircraft employed an evolved version of the rocket engine originally used in the He 176.

Specifications (He 176 V1)

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Heinkel He 176 V1 depicted with retracted main landing gear