Warplanes of Germany: Luftwaffe Focke-Wulf Fw 191

Focke-Wulf Fw 191

(Luftwaffe Photo)

The Focke-Wulf Fw 191 was a prototype German bomber of the Second World War, as the Focke-Wulf firm's entry for theBomber B advanced medium bomber design competition. Two versions were intended to be produced, a twin-engine version using the Junkers Jumo 222 engine and afour-engine variant which was to have used the smaller Daimler-Benz DB 605engine. The project was eventually abandoned due to technical difficulties with the engines.

In July 1939, the Reichsluftministerium (RLM) issued a specification for a high-performance medium bomber (the "Bomber B" program). It was tohave a maximum speed of 600 km/h (370 mph) and be able to carry a bomb load of4,000 kg (8,820 lb) to any part of Britain from bases in France or Norway.Furthermore, the new bomber was to have a pressurized crew compartment, of the then-generalized "stepless cockpit" design (with no separatewindscreen for the pilot) pioneered by the Heinkel He 111P shortly before thewar and used on most German bombers during the war, remotely controlled armament, and was to be powered by two of the new 2,500 PS (2,466 hp, 1,839 kW)class of engines then being developed (Jumo 222 or Daimler-Benz DB 604), withthe Jumo 222 being specified for the great majority of such twin-engined designs, that Arado, Dornier, Focke-Wulf and Junkers had created airframedesigns to use. The Arado E.340 was eliminated. The Dornier Do 317 was put on alow-priority development contract; and the Junkers Ju 288 and Focke-Wulf Fw 191 were chosen for full development.

Dipl. Ing E. Kösel, who also worked on the Fw 189 reconnaissance aircraft, wassupposed to have led the design team for the Fw 191. Overall, the Fw 191 was aclean, all-metal aircraft that featured a shoulder-mounted wing. Two24-cylinder Jumo 222 engines (which showed more promise than the DB 604engines) were mounted in nacelles on the wings. An interesting feature was theinclusion of the Multhopp-Klappe, an ingenious form of combined landing flapand dive brake, which was developed by Hans Multhopp. Fuel was carried in fivetanks located above the internal bomb bay and two tanks in the wing between theengine nacelles and fuselage.

The tail section was of a twin fins and rudders design, with the tailplanehaving a small amount of dihedral. The main landing gear legs retracted to therear and rotated 90° to lie flat in each engine nacelle with the mainwheelsresting atop the lower ends of the gear struts when fully retracted, much likethe main gear on the production versions of the Ju 88 already did. Also, the tailwheelretracted forwards into the fuselage. A crew of four sat in the pressurizedcockpit, and a large plexiglas dome was provided for the navigator; the radiooperator could also use this dome to aim the remotely controlled rear guns.

The Fw 191 followed established Luftwaffe practice in concentrating the crew inthe nose compartment, also including the nearly ubiquitous Bola,inverted-casemate undernose gondola for defensive weapons mounts first used onthe Junkers Ju 88A before the war, and in the use of a "steplesscockpit", having no separate windscreen for the pilot, as the later -P and-H versions of the Heinkel He 111 already did. This was pressurised forhigh-altitude operations. The proposed operational armament consisted of one 20mm MG 151 cannon in a chin turret, twin 20 mm MG 151 in a remotely controlleddorsal turret, twin 20 mm MG 151 in a remotely controlled ventral turret, atail turret with one or two machine guns and remotely controlled weapons in therear of the engine nacelles. However, different combinations were mounted inthe prototype aircraft. Sighting stations were provided above the crewcompartment, and either end of the Bola beneath the nose.

The aircraft had an internal bomb bay. In addition, bombs or torpedoes could becarried on external racks between the fuselage and the engine nacelles. Thedesign was to have had a maximum speed of 600 km/h (370 mph), a bomb load of4,000 kg (8,820 lb), and a range allowing it to bomb any target in Britain frombases in France and Norway.

It is said that the intention to use electric power for almost all of theaircraft's auxiliary systems (as used on the Fw 190 fighter), requiring theinstallation of a large number of electric motors and wiring led to a nicknamefor the Fw 191 of "Das fliegende Kraftwerk" ("the flyingpowerstation").[citation needed] This also had the detrimental effect ofadding even more weight to the overburdened airframe, plus there was also thedanger of a single enemy bullet putting every system out of action if thegenerator was hit. Dipl. Ing Melhorn took the Fw 191 V1 on its maiden flightearly in 1942, with immediate problems arising from the lower rated engines notproviding enough power, as was anticipated. The Multhopp-Klappe, gave severeflutter problems when extended, and indicated a need for a redesign. At thispoint, only dummy gun installations were fitted and no bomb load was carried.After completing ten test flights, the Fw 191 V1 was joined by the similar V2,but only a total of ten hours of test flight time was logged. The 2,500 PS(2,466 hp, 1,839 kW) Junkers Jumo 222 engines which would have powered the Fw191 proved troublesome. In total only three prototype aircraft, V1, V2 and V6,were built. The project was crippled by engine problems and an extensive use ofelectrical motor-driven systems. Problems arose almost immediately when theJumo 222 engines were not ready in time for the first flight tests, so a pairof 1,560 PS (1,539 hp, 1,147 kW) BMW 801A radial engines were fitted. This madethe Fw 191 V1 seriously underpowered. Another problem arose with the RLM'sinsistence that all systems that would normally be hydraulic or mechanicallyactivated should be operated by electric motors.

At this point, the RLM allowed the redesign and removal of the electric motors(to be replaced by the standard hydraulics), so the Fw 191 V3, V4 and V5 wereabandoned. The Fw 191 V6 was then modified to the new design, and also a pairof specially prepared Jumo 222 engines were fitted that developed 2,200 PS(2,170 hp, 1,618 kW) for takeoff. The first flight of the new Fw 191 took placein December 1942 with Flugkapitän Hans Sander at the controls. Although the V6flew better, the Jumo 222 were still not producing their design power, and thewhole Jumo 222 development prospect was considered dubious due to the shortageof special metals for it. The Fw 191 V6 was to have been the productionprototype for the Fw 191A series.

Due to the German aviation engine industry having chronic problems in producingengines capable of equal to or more than the 1,500 kW (2,000 PS) figure duringthe war, that were fit for service, the Jumo 222 engines were having a lot ofteething problems and the Daimler Benz DB 604 had already been abandoned, a newproposal was put forth for the Fw 191B series. The V7 through V12 machines wereabandoned in favor of installing a pair of Daimler Benz DB 606 or 610"power system" engines (basically coupled pairs of either DB 601 or605 12-cylinder engines) in the Fw 191 V13. Their lower power-to-weight ratio(each "power system" weighed 1.5 tonnes) meant that the armament andpayload would have to be reduced. It had already been decided to delete theengine nacelle gun turrets, and to make the rest manually operated. Five moreprototypes were planned with the new engine arrangement, V14 through V18, butnone were ever built, possibly from the August 1942 condemnation byReichsmarschall Hermann Göring of the coupled "power system" DB 606and 610 powerplants as "welded-together engines", in regards to theirbeing the primary cause of the unending series of powerplant problems in theirprimary use, as the engines on Heinkel's Heinkel 177A Greif, Germany's onlyheavy bomber to reach production in the Second World War.

One final attempt was made to save the Fw 191 program; the Fw 191C was proposedas a four engined aircraft, using either the 1,340 PS (1,322 hp, 986 kW)Junkers Jumo 211F, the 1,350 PS (1,332 hp, 993 kW) DB 601E, the 1,475 PS (1,455hp, 1,085 kW) DB 605A or similar rated DB 628 engines. Also, the cabin would beunpressurized and the guns manually operated, with a rear step in the bottom ofthe deepened fuselage — in the manner of the near-ubiquitous Bola gondola usedby the majority of German bombers for ventral defense under the nose — beingprovided for the gunner. Focke-Wulf used the designations Fw 391 and Fw 491 forthe different variants of the Fw 191C, but these were unofficial and neverallocated by the RLM.

The "Bomber B" program had been canceled, due mainly to no engines ofthe 2,500 PS class being available, which was one of the primary requirementsin the "Bomber B" program. Although the Fw 191 will be remembered asa failure, the airframe and design eventually proved themselves to be sound;only the underpowered engines and insistence on electric motors to operate allthe systems doomed the aircraft. There were only three Fw 191s built (V1, V2and V6), and no examples of the Fw 191B or C ever advanced past the designstage. The RLM kept in reserve for Focke-Wulf the designation Fw 391 forfollow-up designs but nothing came of it and the project was eventuallyscrapped. (Wikipedia)

(Luftwaffe Photos)

Focke-Wulf Fw 191, Bomber B design competitor (prototype).

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