Hybrid Aircraft - Messerschmitt Bf.109 mutations

Germany's legendary Messerschmitt Bf.109 fighter underwent numerous modifications in the course of its service, from the slightly angular early models which saw action in the Spanish Civil War, to the sleek late series, exemplified by the 109G.

Inevitably some served as test-beds for various proposals. The 109F, for example, was used to test the Jumo 213 engine and BMW 801 radial engine, producing a hybrid Bf.109 with the nose of an FW.190. A butterfly tail unit produced a Bf.109F/4V variant, which displayed better performance and flight characteristics than the standard model, but was not accepted by the authorities and therefore went nowhere. A Bf.109F-1 was rested with tricycle undercarriage for trials associated with the Me.262 jet.

The Bf.109Z represented one of the more interesting experiments with the 109 airframe. Two Bf.109F-1 fuselages were joined by a new common wing and tail centre section, removing the outer, original tail surfaces. The resulting aircraft was intended as a prototype for a heavy fighter-bomber in this new configuration, but using the components of the more modern Bf.109G.

In December 1942, four versions of the Bf.109Z were proposed, all accommodating the pilot in the port fuselage. The first was to be a heavy fighter and fighter-bomber powered by DB 605 engines, and armed with five 30 mm MK 108 cannon and 1,100 lb. bomb under the centre wing section.

This version would have a span of 43 ft. 6½ in. and a length of 29 ft. 3½ in., empty and loaded weights of 10,803 lb. and 13,669 lb., and a maximum speed of 441 mph at 23,300 ft.

The second version would be similar, but with two MK 108 cannon and two 2,200 lb. bombs. The third and fourth would be similar to the first two but powered by Jumo 213 engines.

A prototype based on 109F components was completed in the winter of 1942-43, by which time the jet-propelled Me.262 was attracting more interest as a fighter-bomber. The project was shelved before any flight testing was conducted.

The Bf.109TL was proposed in January, 1943 as an alternative to the Me.262. Emphasis was then placed upon simplification of combat aircraft production, and some reluctance was being evinced in committing to entirely new types such as the 262. The 109TL would make use of many existing aircraft components. It would use the fuselage of the Bf.109 or its derivative, the Me.155 (taken over by Blohm & Voss) which was being developed as a shipboard fighter.

The Me.155 wing, modified for the fitting of turbojet engines, would also be used. It would have a tricycle undercarriage, using the nosewheel of an Me.309. The only new components would be the main undercarriage members, the tail assembly, and the fuselage nose. This would house two 30 mm MK 103 cannon with 100 rounds per gun, and one 20 mm MG 151 cannon with 170 rounds.

The performance of the Bf.109TL was expected to at least equal that of the Me.262. Possibly, because of its smaller fuselage cross-section, it would be better.

The Bf.109TL project was investigated until March 1943. It was then seen that continuation of the project would require duplication of much of the test program already completed on the Me.262. The number of existing components which would be completely unaltered was so small as to undermine any value in continuing with the design, and as work had already begun on a series of 150 Me.262A aircraft, any benefit remaining was lost.

The Bf.109 first saw action in the Spanish Civil War, and perhaps fittingly, survived in the form of the HA-1109 series in Spanish service. The Spanish Ministerio del Aire selected the Messerschmitt Bf.109G-2 for licence production in Spain in 1942, with Germany providing 25 airframes for assembly, with pattern drawings, jigs and tools, in 1943, to be followed by power plants, airscrews and cannon armament for a further 200 aircraft. La Hispano-Aviacion was to produce the aircraft.

The war situation meant that only incomplete drawings and 25 airframes reached La Hispano-Aviacion, without tail assemblies, power plants or armament. All the same, in 1944 airframe assembly was started in Seville. It became obvious that Germany was in no position to further support the project, so work began in adapting the Bf.109G-2 airframes to accept the Hispano-Suiza 12-Z-89 12-cylinder upright-vee engine in place of the Daimler-Benz.

The first Bf.109G conversion was flown on March 2nd, 1945, as the HA-1109-J1L. Unfortunately, use of a VDM airscrew meant reduction of permissible engine rpm from 2,800 to 2,600. With a somewhat ungainly carburettor intake adding its drag, the aircraft's performance was disappointing. A Swiss Escher-Wyss airscrew was substituted in January 1946, and the second airframe was completed as the first production HA-1109-J1L, the remaining 23 airframes being completed in similar fashion.

The difficulties with the HS 12-Z-89 engine could not be overcome. The French-built HS 12-Z-17 engine was obtained and fitted in the first Spanish-built airframe. A de Havilland Hydromatic PD-63-335 airscrew was attached. The new aircraft flew in May 1952 as the HA-1109-K1L, deliveries to the Ejercito del Aire beginning the following year, armed with two 12.7 mm Breda-SAFAT machine guns beneath the wings. It had a maximum speed of 404 mph (650 km/h) at 13,780 ft. (4200 m) and cruised at 298 mph (480 km/h) at 9,840 ft (3000 m.). Service ceiling was 32,800 ft (10000 m.).

When Professor Willy Messerschmitt and a number of German technicians arrived in Spain, further developments of the HA-1109-K followed. In the HA-1109-K2L, the machine guns were transferred to the engine cowling, and wing racks were fitted for eight Oerlikon 80 mm rockets. The -K3L dispensed with guns altogether and retained the rocket load. The HA-1112-K1L had two wing-mounted Hispano-Suiza HS-404 or -804 20 mm cannon plus rocket racks.

The HA-1110-K1L was a two-seat conversion trainer. The standard seat was moved slightly forward and a second seat was fitted behind it, both under a single rearward-sliding canopy. The fuel tank behind the pilot was replaced by a slightly smaller tank, and two wing tanks. By the time the two prototypes flew in 1953, a mock-up Rolls-Royce Merlin 500-45 engine had arrived in Spain, and work had begun on adaption of the airframe to take the British engine, to produce the HA-1109-M1L.

This last derivative of the Bf.109 was still flying in the late 1960s, enabling it to stand in for its ancestor in the 1969 movie, "The Battle of Britain", albeit with four-bladed propellor and a nose more like that of a P-40 than a Bf.109. Some of these veterans found their way into the hands of collectors, flying for some years after that.

Bf.109TL data:
SPAN: 41 ft. 2 in. (12.55 m.) LENGTH: 31 ft. 2 in. (9.5 m.) HEIGHT: 9 ft. 6½ in.(2.9 m.) EMPTY EQUIPPED WEIGHT: 6,768 lb. (3070 kg.) (Estimated) LOADED WEIGHT: 10,472 lb. (4750 kg.) (Estimated)	EST. MAX. SPEED: 609 mph (980 kmh) at 29,530 ft. (9000 m) SERVICE CEILING: 37,415 ft. (11400 m) SCHEMATIC DIAGRAM: