Messerschmitt Me 328
On May 29, 1944, Göring gave the order to alter the production of the Me 262 to transform it into
Schnellbomber (fast bomber) and on June 7, the
Führer confirmed its decision at a time when the interceptors were vital to the defence of the Reich. To escape this situation, Messerschmitt decided to revive the project P.1079 of 1941, under the new name Me 328.
It was a single seat fast bomber, built in wood and steel, capable of carrying a bomb of 1,000 kg to London. Its design was so simple that only 4,200 man-hours were needed for its construction, a quarter of the time used by a Bf 109 G. The secret was in its pulsejet engine type, a simple steel tube with very few moving parts and able to work with non-refined petrol
Br-Stoff. Originally designed by Dipl. Ing. Paul Schmidt as SR 500, it had a maximum static thrust of 750 kp and could run for more than twenty hours at 700 kph.
But the improvement required too much time and the RLM chose to finance the construction of the Argus As 109-014, much simpler and with its valve system hosted in a quadrangular air-intake. The Argus pulsejet could not be throttled for lack of fuel pump, which had been removed to simplify the design. The fuel system was pressurized by means of compressed air bottles. The life of the flap valves was 20 minutes and only produced 366 kp thrust at 3,000 m ceiling. When mass manufacturing of the missile V-1 was ordered, the huge amount of orders of pulsejets saturated the production capacity of the manufacturer preventing any further refinement of the engine.
None of this was expected when Messerschmitt decided to build the Messerschmitt Me 328. With the SR 500 cancelled, it was anticipated that the Argus would get an upgraded version of the 014, with 400 kp thrust, capable of operating at 793 kph. It also existed as As 109-044, of 500 kp, and it was predictable that its manufacturing would start in 1945.
The first option of Messerschmitt had been the P.1079/1 project, a swept wing fast bomber powered by a SR 500, capable of carrying a bomb SD 1700 at 760 kph. Having to use the As 014, the fast bomber P.1079/16 (March 16, 1941) was redesigned in twin engine configuration with straight wing. It was expected to only reach a maximum speed of 530 kph, somewhat slower than a Spitfire Mk.II and that it would be a secure prey for the Tempests Mk.V that would try to hunt it in 1944.
To test the basic aerodynamics of the P.1079 /16, the DFS Institut was commissioned to build a flying mock-up with a wood/plywood. It was a small plane with classic shapes and a circular section fuselage that was used for initial aerodynamic trials, mounted above a Do 217 E-3 on a
Mistelschlepp configuration. The special rig that held both aircraft was equipped with strain and pressure gauges to quantity the forces exerted on wings and tailfins during flight. The tests were initiated at Linz Hörsching airfield on July 23, 1941.
Doubts about the availability of the pulsejets kept the project frozen until mid 1943 when the construction of two prototypes for gliding tests were commissioned. The Me 328 V1 was built in wood/plywood by Jacobs-Schweyer Flugzeugbau GmbH in Darmstadt. The Me 328 V2 was commissioned to Kithelberger-Bregenz am Bodensee, had the nose fuselage and the tailfin built in light-alloy and the rest of the airframe in wood/plywood. The first flight tests of both prototypes were made in Hörsching using a Do 217 E-3 bomber with conventional
Langseilschlepp cable-towing system. The take-off took place on a detachable dolly and the landing on a retractable ventral skid. They were launched from heights between 9,800 and 19,700 ft. During descent, both prototypes showed good characteristics of stability and manoeuvrability. Hanna Reitsch reached a speed of 600 kph piloting the V1 and estimated that its maximum speed in dive could reach 730 kph.
In April 1944 flight tests started with two pulsejets VSR-7, an older version of Argus 109-014 with external fuel pumps, during which both prototypes suffered structural damage due to sonic shockwaves produced by this type of engine. Although according to some sources the wings were destroyed by vibration and not by sound. The operation of two VSR-7 could not be synchronized in flight as the pilot lacked effective control over the fuel pumps that had been installed to replace the pressurized air fuel system. The fuel pumps were powered by electric engines and the electricity to operate them came from two wind-driven generators in the wings, originally designed for the Me 163. To solve the problem of vibrations, it was decided to install the pulsejets to both sides of the rear section of the fuselage, which in the V3 prototype had been built of metallic structure and coating by Gothaer Waggonfabrik.
Flight tests were conducted with the V3 between September and November 1944 in Hörsching, using a Do 217 bomber with the V3 in
Mistelschlepp configuration. The prototype was built as a fighter, with flat windshield and armed with two MG 151/20 cannons. Tests were disappointing, as the VSR-7 only worked acceptably at low altitude, losing power very quickly above 9,000 ft. A new attempt made with two Argus As 109-014 could only worsen the problem of vibration, to the extent that Messerschmitt technicians used explosive bolts to fix them so that the airplane might be detached in case of emergency.
The Me 328 should have been cancelled in the fall of 1944, but it was decided to continue the project with the intent to deter the
Führer of its decision about the Me 262, offering him a cheaper and easier bomber to manufacture. To the seven projects of fighters and bombers initially proposed to the OKL on December 15, 1942, numerous alternative versions were added in the summer of 1944, including U-boat launched and railways-launched suicide bombers and emergency jet fighters.
At the end of 1942, the limitations of pulsejets for flight at high altitude were not known and the production of three types of fighters based on the P.1079/16 airframe was considered.
The Me 328 A-1 (December 15, 1942) was designed as
Bordjäger (parasite fighter) to protect the long-range reconnaissance airplanes against Allied naval fighters. It would be transported in
Mistelschlepp configuration over a Heinkel He 177 A-5 or a Messerschmitt Me 264. With a flight endurance of only 20 minutes, it was considered a suicide project as the pilot possibilities of being picked up by a U-boat or Allied destroyer were even more remote than those of a pilot of a Hurricane 'Catafighter'.
The A-1 was based on the airframe of the V3, with the fuselage built in light alloy, the wings in wood/plywood and the tailplane of a Bf 109 F. It would be powered by two VSR-7 pulsejets with 150 kp thrust each. Designed to combat against fighters, it would enjoy a light armament of two MG 151/20 cannons, with 200 rounds each, and rear armoured against 20 mm shells. It would be connected to the mother plane for an oxygen system and an intercom connection. On both sides of the nose, there would be two wind-driven generators of 2,000 watts each for supplying electric power to the FuG 16 radio set, the Revi gunsight 16 and the fuel pumps. The landing device would consist of a ventral retractable skid powered by compressed air bottles.
Technical data
Wingspan: 6.4 m, Length: 7.5 m, Height: 2.7 m, Wing Area: 7.5 sq m, Estimated Maximum Speed: 755 kph, Landing Speed: 165 kph, Maximum Weight: 2,200 kg, Estimated Ceiling: 12,000 m, Estimated Rate Climb: 16 m/sec, Estimated Range: 770 km.
The Me 328 A-2 (December 15, 1942)
The Me 328 A-2 (December 15, 1942) was designed as a point-defence interceptor. Various methods of taking-off were proposed: A Madelung KL 12 steam catapult, a rocket-propelled three-wheel trolley or a rail rocket-propelled launch cart. As bomber destroyer, it would be powerfully armed with two MK 103/30 and three MG 151/20 cannons in the nose. Excessive weight required the use of four VSR-7 pulsejets and extended wingspan with which it was expected to achieve a climb rate of 25 m/sec.
Technical data
Wingspan: 8.5 m, Length: 7,5 m, Height 2.7 m, Wing Area: 12 sq m, Estimated Maximum Speed: 920 kph, Landing Speed: 145 kph, Maximum Weight: 3240 kg, Estimated Range: 485 km, Endurance: 30 minutes.
Me 328 A-3 (December 15, 1942)
Designed as
Bordjäger for the defence of the Junkers Ju290 Z, a twin fuselage reconnaissance aircraft with 11,000 km range. The fighter was transported on the back of the starboard fuselage in
Huckepack configuration, a system of extensible rods that avoided shocks during the detach process due to turbulence. After the combat, the Me 328 resupplied fuel via a device located at the back of the mother plane, which also could be used as a towing system during the trip back to base. The A-3 was a version of the A-2 with armament reduced to only two MG 151/20 in the nose.
Me 328 B-0 (December 15, 1942)
Designed as 'Schnellbomber' (fast bomber) to attack targets located in the south of England. It would be fitted with
Kuto-Nase systems (cable cutter) to the extreme nose and wing leading edges to get through the balloon barrages, as well as one shoulder wing to facilitate take-off from a modified catapult
Madelung-Schleuder KL 12. The airframe would be built entirely of wood/plywood with the tailplane of a Bf 109 F standard. It would be powered by two Argus pulsejets with 300 kp thrust each and armed with a SC 1000
Hermann bomb. The auxiliary equipment consisted of a Revi 16b gunsight, a FuG 16 Zy RT device, a FuG 25th IFF system and two wind driven generators in the wingtips. The B-0 should have to fly at very low altitude to avoid radar detection by the 'Chain Home' and did not require oxygen system installation.
The cockpit was equipped with 80 mm armoured glass windscreen and from the rear with 15 mm steel plating. The landing was made over a retractable skid helped by flaps, with both systems powered by compressed air bottles. When the project was cancelled, the Jacob-Schweyer Flugzeugbau (JSF) firm had already begun construction of 20 airframes.
Technical data
Wingspan: 8.6 m, Length: 7.24 m, Height: 2.5 m, Wing area: 9.4 sq m, Range; 630 km with two fuselage fuel tanks of 670 litres, Maximum Speed (clean) 680 kph, Landing Speed: 142 kph.
Me 328 B-1 (December 15, 1942)
B-0 variant with extended range, towed by a He 111 mother- plane in
Deichselschlepp configuration. It was designed with low wing, increased fuel capacity, a new cockpit hood and the possibility of installing an ejector seat.
Technical data
Maximum Speed (clean) 680 kph, Maximum Speed (with one SC 1000 bomb): 590 kph, Ceiling (clean): 6,800 m, Ceiling (with one SC 1000 bomb.): 4,000 m, Maximum Weight: 4,250 kg, Range (with two 670 litres fuel tanks and one of 510 litres): 870 km.
Me 328 B-2
B-1 variant designed as a medium-range antiship bomber, powered by two Argus pulsejets of 400 kp thrust that would allow it to reach 630 kph loaded with a bomb SD 1,400, and 810 kph in clean aerodynamic configuration. It was considered to increase its fuel capacity by installing a second fuel tank of 510 litres in the rear of the fuselage. It would possibly have used a TSA bombsight.
Me 328 B-3
B-2 variant with extended range and two wingtips fuel tanks with 300 litres each, capable of attacking allied ships located at 1400 km from their base. It could carry a PC 1800 RS bomb or a BT 1000 RS torpedo-bomb. Both bombs were equipped with a rocket engine to increase the impact speed. In clean configuration, the B-3 could reach a maximum speed of 810 kph. Estimated ceiling for this version ceiling was 7,100 m (Clean) and of 5,500 m with a PC1800 RS bomb.
Me 328 S.O.
During the winter of 1943-1944, the
Reichenberg Commitee Institut initiated contacts with DFS to study the transformation of the Me 328 into a S.O. bomber. Under the leadership of General Korten, the 5./KG 200 was commissioned to train 70 new S.O. pilots using a version of the
Stummel Habicht glider with 8 m. wingspan. According to an interview conducted by the BBC to Hanna Reitsch in 1976, the series manufacturing of the version
Totaleinsatz of the Me 328 began in Thuringia by mid-1944, possibly in the old Sonnenberg factory where the DFS 230 gliders were built and that was destroyed during a bombing. Perhaps this circumstance led to reconsider the option of building a manned version S.O. from the Fieseler Fi 103.
Institutional struggle between the
Reichenberg Commitee and the OKL continued until the end of the war in Europe. In October 1944, the obtl. Werner Baumbach took charge of the KG 200, immediately disbanding the entire
Reichenberg unit, perhaps to prevent that the success of such tactics could make them mandatory later. The Me 328 S.O. would have been a variant not powered by the B-2 for antiship or
Pulkzerstörer use, possibly towed aloft by an Arado Ar 234 C. The antiship version of the Me 328 S.O. could carry a SHL 800 hollow-charge warhead for attacks against capital ships or an LT F5b torpedo warhead for attacks on troop transport ships. In the
Pulkzerstörer version the fuel tanks would be replaced by 2,400 kg of HE
Amatol or
Nitropenta that would be detonated by radio-signal or manually when the plane were densely surrounded by enemy bombers.