Wooden fighters of World War 2 – the Heinkel He 162 (I)

A primary concern for many of the nations involved in World War II was the possible effect that a shortage of strategic light metals, such as aluminium, would have on the manufacture of warplanes. Most therefore investigated the use of materials of which there was likely to be no scarcity, and while a few made greater use of wood, the majority turned to wood – a plentiful resource and one which could exploit the skills of experienced craftsmen.

One such aeroplane developed in Germany, to a notably advanced concept and powered by a single turbojet engine, was the Heinkel He 162, often known as the Volksjäger (people’s fighter). This was one of the fruits of the Jägernotprogramm (fighter emergency programme) agreed on 3 July 1944 for the creation of simple but nonetheless advanced warplanes which could be designed and built to prototype level very swiftly, be manufactured in large numbers very rapidly, and make minimum demands on scarce materials and skilled manpower otherwise deployed for other purposes.

The He 162 was in every respect a prodigious effort that confirmed the extraordinary feats of which the German aero industry was capable under the emergency conditions that prevailed in the last months of World War II, for a mere 69 days separated the beginning of the programme from the maiden flight of the first prototype. The type resulted from a specification issued by the Reichsluftfahrtministerium in September 1944 calling for a high-performance fighter that on the one hand would be capable of decimating the fleets of US bombers roaming the skies over Germany with little hindrance, but on the other hand would be built largely of non-strategic materials by a semi-skilled work force, and would be available for mass production at the very beginning of January 1945.

The Volksjäger concept was largely the brainchild of Otto Saur, the energetic protégé of the minister of armaments, Albert Speer, and the leader of the Jägerstab (fighter staff) established on 1 March 1944 within the Reichskriegsministerium. On 8 September 1944, a basic project requirement drawn up by the Technisches Amt along the lines proposed by the Jägerstab was issued to Arado, Blohm und Voss, Fieseler, Focke-Wulf, Heinkel, Junkers and Messerschmitt. The fighter envisaged by this requirement was to be powered by a single BMW 109-003 Sturm axial-flow turbojet engine and, weighing no more than 4,409 lb (2000 kg) fully loaded, was to carry the fixed forward-firing armament of either one or two 30-mm cannon, be capable of speeds greater than 405 kt (466 mph; 750 km/h), possess a flight endurance of 30 minutes at sea level, and take-off within 1,640 ft (500 m). It had to be ready for mass production by 1 January 1945, and the submission date for the draft projects was 20 September 1944.

Dissenting voices

Vehement opposition came from the General der Jagdflieger, Generalleutnant Adolf Galland, who advocated the concentration of all Germany’s remaining aircraft manufacturing potential on the excellent Messerschmitt Me 262 turbojet-powered fighter, and by such eminent designers as Willy Messerschmitt and Kurt Tank, whose objections were based on what they considered to be totally unrealistic specifications and conditions laid down for construction. Despite this opposition, the submission date for the draft projects was brought forward by six days to 14 September.

 A conference was convened at the RLM on 15 September, by which time a hurried preliminary evaluation of the draft projects had been made. Messerschmitt had refused to submit any proposal, and that submitted by Focke-Wulf was unrealistic. Arado’s project was rejected, and Heinkel’s project was also considered unsuitable. Thus the Blohm und Voss concept was deemed the best of those submitted. The Heinkel company was represented at the conference by one of its directors, Dr-Ing. Francke, who was told that his company’s proposal was unacceptable on the grounds that it offered a sea-level flight endurance of only 20 minutes, the unusual location of its powerplant, above the fuselage to the rear of the cockpit and exhausting between the two vertical tail surfaces, would undoubtedly result in maintenance problems, it did not meet the stipulated take-off requirements, it would demand too long a time for disassembly for rail transportation, and it was intended to carry 20-mm cannon rather than the 30-mm type specified. Francke protested that the other submissions had their weights and performances calculated by a different formula to that employed by his company, thereby placing the Heinkel submission in an unfavourable light, and on the following day the other participants in the contest began recalculating the weights and performances of their proposals on the same basis as that used by Heinkel.

On 19 September, a further conference was held at the RLM and all the proposals were reviewed, these including the existing Arado, Blohm und Voss and Heinkel, projects as well as new proposals from Fieseler, Focke-Wulf, Junkers and Siebel. It was again decided that the Blohm und Voss contender, the Projekt 211, was superior in every respect to the other contenders, but the meeting terminated in a heated quarrel between Dr Frydag, director of the main committee for airframes and Heinkel’s former general manager, who disagreed with the decision, and Flieger-Stabsingenieur Schwarz representing Blohm und Voss. Thus no final choice was made.

Development work ordered

Despite the failure to reach a decision during the RLM conference, the decision in principle for mass-production of a Volksjäger was finalised during discussions held at Reichsmarschall Hermann Göring’s headquarters on 23 September. On the same day the chief of the engineering division of the Generalluftzeugmeister-Amt, Dipl.-Ing. Lucht, inspected a mock-up of Heinkel’s contender at Schwechat. Siegfried Günter and Karl Schwarzler, the chief project engineer and chief designer respectively, had in fact been working along broadly similar lines to the Volksjäger concept since a time early in the summer, having evolved a design for a small and unsophisticated jet fighter which they had dubbed the Spatz (sparrow), and to obtain the necessary data on the characteristics of the proposed BMW 109-003 turbojet engine for the fighter, the Heinkel He 219 V14 had been hurriedly adapted as a flight testbed with the attached to the underside of the fuselage by means of a short pylon. Flight trials had begun at Schwechat in July 1944, and thus Heinkel was well positioned when the Volksjäger requirement was eventually announced.

Günter and Schwarzler then worked to adapt the Spatz project to meet the Volksjäger specification, and many of the personnel working on what had now become Projekt 1073 did not to leave their offices for several weeks, sleeping by their drawing boards. Although no official choice of a project had been made, political considerations had already overridden dissenting voices. Saur had already decided that the Projekt 1073 was to be his Volksjäger, and Göring was giving his full support.

Thus, on 24 September, work began on the construction of the P.1073, work on detailed drawings proceeding in parallel.

Another conference was held at the RLM on September 30, and this time the selection of the Heinkel proposal was announced, despite heated protests from Schwarz and other committee members. The P.1073 was ordered into immediate quantity production with an initially proposed output of 1,000 aircraft per month! The new Volksjäger was initially designated as the He 500, but during October and in an effort to puzzle Allied intelligence, the Technische Amt ordered the fighter’s redesignation as the He 162, the numeral having been allocated earlier to Messerschmitt’s Schnellbomber competitor to the Junkers Ju 88. At the same time, the code name ‘Salamander’ was bestowed on the programme: this was not, as subsequently widely believed, the name of the fighter.

The final detailed drawings for the He 162 were completed on 29 October, one day ahead of the schedule demanded by the Technisches Amt, and the first prototypes had already reached an advanced stage in assembly. Unprecedented in the history of aircraft manufacture was the fact that development, pre-production series and quantity production lines had been started almost simultaneously and were proceeding in parallel. Three final assembly plants for the He 162 had been designated: Heinkel-Nord at Marienehe and Junkers at Bernburg were each being expected to attain a monthly output of 1,000 machines, and Mittel-Werke at Nordhausen was scheduled to reach an eventual monthly output of 2,000 machines. These assembly plants were to be fed with components by a vast complex of subcontractors. All wooden components were to be produced by two specially organised groups of woodworking and furniture-manufacturing concerns in the vicinity of Erfurt and Stuttgart; metal fuselages were to be produced by the Heinkel plants at Barth in Pomerania, Pütnitz in Mecklenburg, Stassfurt in Saxony, and Oranienburg outside Berlin, as well as by the Junkers factories at Schünbeck, Aschersleben, Leopoldshall, Halberstadt and Bernburg.

The BMW 109-003 turbojet engine was to be manufactured in a former salt mine near Urseburg to which the Berlin-Spandau and Basdorf-Zülsdorf engine factories had been transferred. Other former salt mines brought into the programme were those at Egeln and Tarthun, both of which were to produce metal fuselages.

The responsibility for all development work and the construction of the pre-production series of aircraft was allocated to the Schwechat factory, and this facility was to integrate itself progressively with the mass production programme, using an underground factory that was being established in a former chalk mine at Hinterbrühl, near Modling just outside Vienna. The entire programme was to be managed by a specially created construction group, the Baugruppe Schlempp, headed by Heinrich Lübke, and the schedule called for the first 1,000 examples of the He 162 to be ready by the end of April 1945, and output to attain 2,000 machines monthly from May 1945.

Construction details

The He 162’s fuselage was a light alloy semi-monocoque structure with a moulded plywood nose cap. The single-piece wing was primarily of wood with plywood skinning and detachable metal tips, and this wing was attached to the fuselage mainframes by four bolts. Hydraulically operated flaps were fitted between the fuselage and ailerons. The tailplane, elevators and rudders were of light alloy construction, but the fins were of wooden construction. The tailplane was set at a moderate dihedral angle, and its incidence could be adjusted by movement of the tail cone. The landing gear was of the tricycle type with a single wheel on each unit, and the narrow-track main units as well as the nose unit were housed entirely in the fuselage, being retracted hydraulically and lowered by spring.

The engine was attached directly to the top of the fuselage, immediately to the rear of the cockpit, by two vertical bolts at the forward end and one horizontal bolt at the rear. The front and rear cowlings were fixed to the powerplant, the centre cowling comprising two hinged segments held shut by quick-release fastenings and opening sideways to permit inspection and maintenance. The normal fuel supply of 152.9 Imp gal (183.6 US gal; 695 litres) was housed in a single flexible fuselage tank, but the capacity of this tank could be increased to 168.3 Imp gal (202.1 US gal; 765 litres) and augmented by an integral wing tank with a capacity of of 39.6 Imp gal (47.6 US gal; 180 litres); single-point fuelling was employed. Cockpit entry and egress were provided by a rear-hinged jettisonable blown canopy, and the pilot was provided with a simple Heinkel-designed ejection seat catapulted from the cockpit by means of an explosive cartridge.

In deference to RLM insistence, it was intended to mount a fixed forward-firing armament of two 30-mm MK 108 cannon in the fuselage sides beneath the cockpit, but in the event, the severe vibration that resulted when these weapons were fired, coupled with the fact that space could be found for only 50 rounds per gun, led to the replacement of this armament in the He 162A-1 by the originally proposed pair of 20-mm MG 151/20 cannon with 120 rounds per gun.

Maiden flight

The He 162 V1 first prototype recorded its maiden flight at Schwechat on 6 December 1944 in the hands of Flugkapitän Peter, and by this time quantity production was on the increase with two 12-hour shifts being worked. During its 20-minute initial flight, the He 162 V1 attained 453 kt (522 mph; 840 km/h) at 19,685 ft (6000 m) before the test was brought hurriedly to a conclusion when a landing gear door broke away as a result of defective bonding. Apart from some longitudinal instability, Peter reported satisfactory handling characteristics, but four days later, in front of a large gathering of RLM, Luftwaffe and Nazi party officials at Schwechat, the starboard wing leading edge ripped away during an unscheduled low-level run across the airfield at high speed. The prototype immediately started rolling, the starboard aileron and wing tip broke away, and the aeroplane crashed just outside the airfield boundary, Peter losing his life. Examination of the wreckage revealed defective bonding as the cause of the accident, but this was not allowed to delay the programme.

In order to remove some disquiet displayed in certain quarters as a result of the loss of the He 162 V1, the technical director, Dr-Ing. Francke, decided that he would personally fly the He 162 V2 second prototype on its initial flight. This event took place on 22 December, and during this and subsequent demonstration flights, Francke took the fighter to its structural limits. The He 162 V2 was subsequently used for firing trials of the two 30-mm cannon, and in the meantime the He 162 V3 third prototype was modified in the light of experience with the first two machines, a weight being fitted over the nose wheel to bring the centre of gravity forward, pronounced anhedral being applied to the wing tips to reduce the effective dihedral angle, and the tail assembly being slightly enlarged. Similar changes were applied to the He 162 V4 fourth prototype, and both of these prototypes made their initial flight on 16 January 1945.

Although issued with Versuchsflugzeug (experimental aeroplane) numbers, the prototypes were also considered to be He 162A-0 pre-production and service test fighters, of which 10 had been ordered from Schwechat, with production-standard He 162A-1 fighters to come in parallel from the nearby Hinterbrühl facility. The He 162 V5 was completed for static tests, and the He 162 V6, first flown on 23 January 1945, was the last of the pre-production aircraft to be fitted with MK 108 cannon. The He 162 V7 was considered as an He 162A-1 airframe and, used for vibration tests, embodied some structural strengthening, while the He 162 V8 was the first test aeroplane to mount the newly standardised armament of two 20-mm MG 151/20 cannon, and the He 162 V9 and He 162 V10 were completed to similar standards.

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