| He 176 | |
|---|---|
 Post war artist impression of the He 176 | |
| General information | |
| Type | Experimental |
| Manufacturer | Heinkel |
| Status | Cancelled |
| History | |
| First flight | 20 June 1939 |
TheHeinkel He 176 was aGerman experimentalrocket-powered aircraft. It was the world's first aircraft to be propelled solely by aliquid-fueled rocket, making its first powered flight on 20 June 1939 withErich Warsitz at the controls.
The He 176 was developed as a private venture by the Heinkel company in accordance with directorErnst Heinkel's emphasis on developing technology for high-speed flight. Work on the project began in 1936 after testing with a modifiedHe 72 and a pair ofHe 112s had shown rocket propulsion to have some viability. The He 176 was purpose-built to harness this propulsion, rather than a modification of existing piston engined-types. The resulting aircraft, largely composed of wood, was of relatively simple build in some aspects, and relatively compact. It incorporated some novel concepts, such as an unconventional reclined seating position for the pilot and a unique jettisonable nose escape system for emergencies. In December 1937 the aircraft was officially designated He 176.
On 12 September 1939, the He 176 project was ordered to be cancelled, apparently due to the aircraft's unimpressive size and performance. However, the aircraft did provide "proof of concept" for rocket propulsion and high speed flight in general; lessons and designs cues were incorporated into subsequent aircraft such as theHeinkel He 280 prototype jet fighter and theMesserschmitt Me 163 rocket interceptor. The prototype itself along with most documentation related to the He 176 had been destroyed by the end of the war. Warsitz considered that some material may have entered theSoviet/Russian archives. The often-quoted performance data of the aircraft, such as its speed reaching 750 km/h, or 800 km/h, is drawn from Warsitz's account, and are usually not based on sound documents. Only two true pictures of the He 176 have survived, probably taken inPeenemünde during testing.[1]
During the 1920s,Germandaredevils and inventors had experimented with the use of solid-fuel rockets to propel various vehicles, such as cars, motorcycles, railway carriages, snow sleds, and, by 1929, aircraft such asAlexander Lippisch'sEnte andFritz von Opel'sRAK.1.[2] Solid-fuel rockets, however, have major disadvantages when used for aircraft propulsion, as theirthrust cannot be throttled, and the engines cannot be shut down while fuel remains.
In the mid 1930s, the aerospace engineerWernher von Braun and his rocketry team working atPeenemünde investigated the use of liquid-fuelled rockets for powering aircraft. The German aircraft designerErnst Heinkel became an enthusiastic supporter of their efforts, initially supplying aHe 72 and later a pair ofHe 112s to support these experiments. During early 1937, one of these aircraft was flown with itspiston engine shut down during flight, propelled by rocket power alone.[3][4] At the same time,Hellmuth Walter's experiments intohydrogen peroxidemonopropellant-based rockets were leading towards light and simple rockets that appeared well-suited for aircraft installation, although at the price of considerable danger and limited endurance.[5][6]
The experimental flights of the He 112 had been subject to the close attention of theReichsluftfahrtministerium (RLM) (the German Reich Aviation Ministry), which had become interested in the potential for a rocket-propelledinterceptor aircraft.[7] Heinkel decided to establish a secret department at itsRostock facility to pursue such endeavours; work commenced as early as 1936.[8] Unlike the preceding He 112, the design team wanted to produce an aircraft purpose-built to harness this new form of propulsion, thus achieving superior performance from it; from this effort the He 176 emerged.[9]
The basic design of the He 176 was sketched out during theNeuhardenberg rocket motor and booster tests. In 1936, theRLM awarded Heinkel the contract to build the world's first rocket aircraft. It was decided to tailor-build the aircraft to specifically fit the test pilotErich Warsitz, minimising the size of thecockpit, along with the rest of the aircraft, thus making the aircraft as lightweight as humanly possible.[10] The resulting cockpit was so cramped that the pilot could not even flex his elbows, and some controls were placed in inconvenient positions. Due to the high speed range that the He 176 was designed to encounter, the sensitivity of these controls had to be adjusted multiple times throughout the flight for the pilot to maintain sufficient control.[11] The cockpit also had an unconventional reclined seating position, adopted to help the pilot cope with the aircraft's high acceleration; it also helped reduce the frontal area and thereby had performance benefits.[11] A crudeplexiglas glazed section was removable so that the pilot could enter the aircraft.[10]
The aircraft itself was relatively compact and in some respects of fairly simple build, made almost entirely of wood, but with an advanced and entirely enclosed cockpit with a frameless single-piece clear nose.[12] Theundercarriage was a combination ofconventional andtricycle gear designs, for which the main gear's struts were intended to retract rearwards into the fuselage while the aerodynamicallyfaired nose wheel and strut were fixed.[13] The greatest diameter of the fuselage was only 700 millimetres (28 in). The overall surface area, including the fuselage, was 5 square metres (54 sq ft), with a 5 metres (16 ft) wingspan, a fuselage length of 5.5 metres (18 ft), a height with the undercarriage deployed at 1.44 metres (4.7 ft), and awheelbase of 700 millimetres (28 in).[14] The aircraft'srudder proved to be relatively ineffective at slow speeds; during takeoff runs, it was found more practical to steer using differential use of the wheel brakes.[12]
The He 176 featured anelliptical wing that had awing sweep of 40% and a thickness of 9% at 90 millimetres (3.5 in).[14] The wing had a slight positivedihedral so that sufficient stability would be maintained.[10] The fuel tanks were integrated into the interior of the wings; a newwelding technique had to be developed to manufacture these. Significant attention was paid to the reduction ofaerodynamic drag.[10] During ground test runs, it was discovered that the wings would often make contact with the ground; to prevent damage to them, the wingtips were fitted with metal bumpers.[12]
The design team recognised that the conventional means of escaping the aircraft in an emergency bybailing out would be extremely difficult at high speed, and perhaps impossible without fatal injury to the pilot.[12] Consequently the He 176 was equipped with a unique jettisonable nose escape system. Compressed air was used to separate the nose from the aircraft, then adrogue chute was used to reduce the opening force required. After the drogue was deployed, the flush-fitting cockpitcanopy was released and the pilot could bailout.[13] Unmanned scale mockups of the nose section were flight tested from aHeinkel He 111 bomber with positive results.[12]
The original model of the He 176 was designed to be powered by one of the newWalter engines. This engine was similar to that of the He 112, the primary difference being the doubling of its thrust output to 6,000 Newtons, largely achieved via the addition of a pump to draw in propellant instead of using compressed air to push the fuel into the engine.[10][15] The fuel used was 82%hydrogen peroxide.[10] To provide more effective directional controls while flying at slow speeds, a rudder was to be installed within the engine nozzle itself.[12] Detailed design work on the aircraft was completed by July 1937, after which construction of the prototype commenced almost immediately.[8] In December 1937, the He 176 designation was officially assigned to the aircraft.[16]
On 20 June 1939, the He 176 performed itsmaiden flight piloted by Warsitz, the occasion being the first manned rocket flight in the world.[8][17] Warsitz later described the flight: "On quite another heading from that originally intended she leapt into the air and flew with a yaw and a wobble. I kept her close to the ground while gaining speed, then pulled back gently on the control stick for rapid ascent. I was at 750 kms/hr and without any loss in speed the machine shot skywards at an angle somewhere between vertical and 45°. She was enormously sensitive to the controls...Everything turned out wonderfully, however, and it was a relief to fly round the northern tip ofUsedom Island without a sound at 800 kms/hr. I banked sharp left again to straighten up for the airstrip, losing such speed and altitude as I could, and during this steep turn the rocket died as the tanks dried up. The abrupt loss of speed hurled me forward in my restraint straps. I pressed the stick forward, hissed rapidly over the Penne and came in at 500 kms/hr. I crossed the airfield boundary and after several prescribed little bounces the machine came to a stop."[18]
Following the initial test flight, the aircraft received alterations; apparently the fixed nose wheel was removed at this point as the design team intended to use only the two main wheels and the tail for regular landings.[10] Following an initial round of flight testing, Heinkel demonstrated the He 176 to the RLM, which, however, showed little official interest. According to Warsitz, speaking of Von Braun's cooperation during the tests atPennemunde: "Although not technically part of the He 176-V1 project with the Walter rocket engine, naturally everything affecting it was of interest to himself and his colleagues because the He 176-V2 was to have the von Braun engine..."[14]
The RLM's unfavourable attitude towards the aircraft was a major contributor to Heinkel's decision to reduce his involvement in rocket propulsion efforts. On 12 September 1939, the discontinuation of the He 176 test programme was officially ordered, apparently due to dissatisfaction with its performance and size.[19][20] Only the one aircraft was ever completed; after its retirement, it was put on static display at the Berlin Air Museum. It was destroyed by anAlliedbombing raid during 1943.[13]
Before the cancellation of the programme, Heinkel had been designing a more sophisticated rocket-powered aircraft, sometimes referred to theHe 176 V2, which was apparently intended for operational use.[10] For this model, a more powerful von Braun engine would have been used, for speeds of up to 1,000 kph (620 mph).[10] No such aircraft was ever constructed, but because it bore the same designation as the aircraft that was actually flown, many books and websites mistakenly publish pictures of this design intended to illustrate its earlier namesake.[citation needed]
Some of the technical knowledge gained through the He 176 was incorporated into future projects undertaken by Heinkel, such as theHe 280 prototype jet fighter.[17]
Germany did eventually fly an operational rocket-propelled fighter, theAlexander Lippisch-designedMe 163Komet, but this was produced by the competingMesserschmitt firm. By the time that orders to terminate work on the He 176 had been received, early work on the Me 163 project had already commenced.[21] It was powered by a similar rocket engine that was actually a further development of the unit that had powered the He 176.[citation needed]
Data fromHeinkel: An aircraft album[22]
General characteristics
Performance
Related lists
