Blohm und Voss Bv 141
BV 141 A-04 (V7) 3-seat reconnaissans aircraft
BV 141 B-02 (V10)
1 BMW 132N     3-bladed variable pitch
1 BMW 801A-0
Length 12.15 m, height 4,1 m, span 15,45 m, wing area 42,85 m2
Length 13,95 m, height 3,60 m, span 17,45 m, wing area 52,90 m2
Empty 3167 kg, flying weight 3900 kg
Empty 4724 kg, normal flying weight 5728 kg, max. take off 6100 kg
Max. speed 340 km/h at sea level, 400 km/h at 3800 m, cruising speed 310
km/h at sea level, 365 km/h at 4500 m, range 1140 km, service ceiling 9000
Max. speed 368 km/h at sea level, 438 km/h at 5000 m, range 1900 km,
service ceiling 10000 m
Guns: 2  fixed forward firing 7.92 mm  MG 17 machine guns and 2 rear-
mounted flexible 7.92 mm MG 15 machine guns
Bombs: 4 × 50 kg  SC50 bombs on under-wing racks
Back in the late 1930s when it appeared that the Nazis would rule the world, Germany decided it needed an observation plane that had great visibility to scout out targets. Bv submitted the Blohm und Voss Bv 141, which had an asymmetrical layout: a tail boom with a radial engine on one side, and a shorter crew compartment (complete with camera) that was almost entirely windscreens on the other. There were three prototypes built in 1938, the last one armed with two 7.92 mm machine guns firing forward and two firing rearward. The manufacturer also added racks for four 11 a-pound bombs. The initial aircraft were considered underpowered, so an additional five Bv 141s were built with more powerful engines. Trials began in late 1941, and stopped in 1943 due to its low speed (compared with Allied fighters and bombers) and because the Luftwaffe needed !it more fighters to protect the Fatherland against around-the-clock Allied bombing.
One of aviation's true oddities the BV 141 performed surprisingly well, but never saw operational service. Three prototypes of the BV 141 were made, before it went into limited production. Only a total of 23 were built.
The similar fuselage, but more conventional twin-engined layout of the Focke-Wulf Fw 189 won out in the end.
Every decade in the history of military aviation has seen its share of the unconventional in aircraft design; warplanes that, in concept or configuration, markedly deviated from what was considered to be orthodox at the time of their debut. Few more unorthodox aircraft appeared in the thirties than Dr.-Ing. Richard Vogt's asymmetrical BV 141 short-range reconnaissance and army co-operation machine which represented a highly novel approach to the problem of endowing a single-engined aircraft with outstanding all-round vision.
Early in 1937, the Reichsluftfahrtministerium (RLM) issued to Arado and Focke-Wulf a specification which called for a short- range reconnaissance aircraft capable of fulfilling the light bomber, low-level attack and smokescreen-laying roles in an emergency. The specification stipulated a three-seat machine, emphasized the need for an outstanding all-round view for the crew members, and demanded 850-900 h.p. for take-off. From an early stage the Arado company's proposal was favored by, the RLM's Technische Amt, this concern eventually being awarded a development contract for what was to be the totally unsuccessful Ar 198. The Hamburger Flugzeugbau had not been invited by the RLM to tender a proposal, but its technical director, Dr.-Ing. Vogt had some revolutionary ideas concerning the best way to fulfil the RLM's specification, and accordingly submitted a private-venture proposal.
The RLM's Technische Amt had not stipulated that total power should be confined to one engine, but it was tacitly assumed that, for the army co-operation role, no designer would consider using more than one power plant. Vogt believed that the only way in which adequate all-round vision for reconnaissance purposes could be provided in a single-engined aircraft was to adopt an asymmetrical configuration, the crew being housed in an extensively-glazed, nacelle offset to starboard. He also believed that virtue could be derived from necessity, the asymmetrically-mounted crew nacelle canceling out the airscrew torque which provided every designer of a single-engined aircraft with some- thing of a headache. His proposal to the RLM was, therefore, for an asymmetric aircraft, but as Arado had already begun construction of the Ar 198, it was hardly surprising that little official interest was evinced in this unconventional design. However, Ernst Udet, newly-appointed chief of the Development Section of the Technischen Amt, showed Vogt some encouragement and, the Hamburger Flugzeugbau management having agreed to finance the project, work began on the strange prototype which, designated Ha 141-0 and registered D-ORJE, flew for the first time on February 25, 1938.
Apart from slight over-sensitivity of the control surfaces and minor undercarriage oscillation, the unorthodox Ha 141-0 proved singularly trouble-free, and after Udet himself had flight tested the prototype, an official contract was placed for three prototypes. The existing prototype was not covered by the contract, but after somewhat protracted negotiations, the RLM agreed to accept the machine as one of the three for which it had contracted, and D-ORJE was promptly allocated Werk-Nr. 172 and eventually redesignated BV 141 V2 when the name of the company was changed from Hamburger Flugzeugbau to Abteilung Flugzeugbau der Schiffswerft Blohm und Voss, while the second prototype became the first official prototype as the BV 141 V1 (Werk-Nr. 171).
The stepped cockpit of the BV 141 V2 (alias Ha 141-0) did not prove acceptable to the RLM and, in consequence, the entire crew nacelle was redesigned for the BV 141 V1, the new nacelle following closely the design of that of the Focke-Wulf Fw 189 which was under development simultaneously, and featuring copious glazing comprising a multitude of flat panels. Provision was made for two fixed forward-firing 7.9-mm. machine guns and two hand-held aft-firing guns of similar calibre (although the first aircraft actually to feature armament was the BV 141 V3), and underwing racks were provided for four 110-lb. bombs. The over-all dimensions of the BV 141 V1 were slightly increased by comparison with the V2, span bBlohm & Voss BV 141 eing extended from 49 ft. 2.5 in. to 49 ft. 6.5 in., resulting in wing area of 449.93 sq. ft. compared with 446.7 sq. ft., and length was raised from 36 ft. 5 in. to 37 ft. 4.75 in.
Registered D-OTTO, the BV 141 V1 weighed 6,812 lb. empty and 8,441 lb. in normal loaded condition, and was rolled out for initial flight trials in September 1938. Early in its test program problems with the hydraulic system were encountered, and on October 5, 1938 a forced landing was made in a ploughed field with the mainwheel legs only half extended, the starboard wing suffering considerable damage. Fortunately, the BV 141 V3 (D-OLGA) was available to participate in the flight test program shortly after the V1 had come to grief, and this aircraft (Werk-Nr. 359) was considered to all intents and purposes a production prototype.
In order to improve directional stability, the BV 141 V3's fuselage had been lengthened to 39 ft. 10.33 in., and overall span was once more increased slightly to 50 ft. 4.33 in., while to improve ground stability the wheel track was widened from 16 ft. 1 in. to 16 ft. 10.33 in. The crew nacelle accommodated the pilot to port with the observer to starboard, and the observer's seat was attached to a track so that when pushed to its forward extremity it enabled him to operate the bomb sight, the radio equipment being situated at the aft end of the seat track. The observer also operated the camera and, in an emergency, the upper aft-firing machine gun. The entire nacelle was of minimum section, measuring only 3 ft. 11.25 in. from side to side. and 4 ft. 11 in. from top to bottom, and terminated in a pointed cone housing a similar 7.9-mm. MG 15-machine gun to that mounted in the upper position. Of Focke-Wulf design, this rear position could be rotated through 360 deg., the gunner being prone over the wing trailing edge.
The tailplane was almost symmetrical, and trim tabs were fitted in the elevators, rudder and port aileron, and the ailerons were balanced by means of two spoilers on each outer wing section, these being interconnected with the ailerons. All control surfaces were actuated by rods, the flaps and undercarriage being hydraulically operated. Power was provided by a nine-cylinder BMW 132N radial air-cooled engine offering maximum power of 865 h.p. for one minute at sea level and 960 h.p. at 9,842 ft., and-this was fed from a 108 Imp. gal. fuel tank immediately aft of the engine firewall. Apart from the two fixed-forward-firing MG 17s and two aft-firing MG 15s on flexible mountings, the BV 141 V3 had four ETC 5b bomb racks and an automatic camera (Rb 20/30, 21/18, 50/18 or 50/30).
Even the RLM, which had viewed the BV 141 with the utmost suspicion from the outset, was forced to admit that, despite its highly unorthodox appearance, the aircraft possessed extremely docile handling characteristics and fully met the original specification. Somewhat reluctantly, an order was placed for a pre-series of five aircraft (BV 1414-01 to 05), but these machines were also allocated Versuchs numbers, and thus the BV 141A-01, which was registered D-OLLE, was also known as the BV 141 V4. This aircraft (Werk-Nr.360) joined the test program early in 1939. Wing span and area were slightly increased, from 50 ft. 4.33 in. to 50 ft. 8.25 in. and from 457.466 sq. ft. to 461.233 sq. ft., but empty weight was actually reduced from 7,064 to 6,845 lb., normal loaded weight remaining constant at 8,598 lb. The "Achilles heel" of the BV 141 remained its hydraulic system, however, and shortly after commencing flight testing the BV 141 V4 suffered an accident when one mainwheel leg locked down and the other remained up during a landing. As this aircraft was intended for trials at the Erprobungsstelle Rechlin there was an inevitable delay in the initiation of the official evaluation program.
The remaining four BV 141 A-0 pre-series aircraft, the V5 (Werk-Nr.361), the V6 (Werk-Nr. 362), the V7 (Werk-Nr. 363), and the Y8 (Werk-Nr. 364), were completed to schedule and were virtually identical to the V4, the only change of any importance being the provision of a new upper defensive position which replaced the sliding hatch. The official flight test program was completed at Rechlin with the BV 141 V5 in January 1940, and the E-Stelle pilots' reports were generally favorable. For low-level bombing a special bomb sight had been developed and installed in the V5, and 13 bombing trials were undertaken, a total of 58 bombs being dropped from various altitudes. The BV 141 V3 also participated in bombing trials at Rechlin and Tarnewitz. The Luftwaffe's High Command, the OKL, displayed little enthusiasm for this "oddity", and on April 4, 1940 succeeded in persuading the RLM to cancel its plans for large-scale production of the BV 141A.
The OKL's lack of enthusiasm for the BV 141 resulted primarily from the unorthodox appearance of the aircraft, and in casting around for a valid technical reason for the rejection of the Blohm und Voss machine, it decided to base its decision on the fact that the BV 141A-0 was marginally underpowered. Dr. Vogt had already foreseen the possibility that more power would be demanded, and as early as January 1939, his team had begun the redesign of the basic aircraft to take the substantially more powerful BMW 801. A complete structural redesign was under-taken, and the final mock-up of what was to be designated the BV 141B was inspected and approved by an RLM commission on February 14,1940. Less than a year later, on January 9,1941, the first of five pre-series BV 141B-A aircraft, the BV 141 V9 (NC + OZ), flew for the first time. At this time, Blohm und Voss held a firm contract for only five BV 141B-0 aircraft, but the RLM had taken options on a further five pre-production machines and 10 production BV 141B-1s.
It was soon obvious that the BV 141B did not share the pleasant characteristics of its predecessor. Static vibration trials in November 1940 had revealed the fact that substantial strengthening of certain components was called for, and it had been found that major modifications had to be made to the tail assembly supports, the undercarriage and the control system. Static tests had been continuously plagued by hydraulic troubles, problems with the undercarriage actuating mechanism and when engine runs had begun, with the BMW 801 power plant itself. By-the time that flight trials began, the results of vibration tests had still to be fully evaluated and, in consequence, the EV 141 V9 had to be limited to a maximum speed of 280 m.p.h. Aileron trimming proved ineffective, the ailerons themselves proved over sensitive, functional defects in the hydraulic system, and numerous other troubles disrupted the entire test schedule.
Completion of the remaining four BV 141B-0 aircraft was slowed pending the satisfactory outcome of modifications to the BV 141 V9. But comparison with the BV 141A, B-series aircraft featured enlarged dimensions, equi-tapered outboard wing panels were introduced, the oval section of the fuselage gave place to a circular section over its entire length, and the tail surfaces were entirely redesigned. Earlier, the BV 141 V2 had tested a further innovation an asymmetric tailplane. In order to improve the rear gunner's field of fire, the starboard half of the tailplane had been removed and the port half increased in size, and as this modification resulted in no noticeable deterioration in handling qualities, the asymmetric tailplane was adopted for the BV 141B.
The BV 141 V9 was eventually delivered to the E-Stelle at Rechlin in May 1941, and it was joined there by the V10 (NC + RA) which had finally flown on June 1, 1941, after having gathered dust for some three months in the Blohm und Voss plant while the delivery of an airscrew was awaited. Constant minor failures troubled the official evaluation program, and when the fourth BV 141B, the V12 (NC + RF), was delivered to Tarnewitz for armament trials, it was discovered that the gun ports were too short, and that cordite fumes filled the cockpit when the guns were fired. In the meantime, the BV 141 V11 (NC + RC) had joined the test program, but teething trouble followed teething trouble, and it was hardly surprising, therefore, that the fifth and last BV 141B, the V13 (NC + RH), was not delivered until May 15, 1943.
In the autumn of 1941, the second BV 141B, the V10, had been delivered to Aufklärungsschule 1 at Grossenhain, Saxony, for trials under service conditions, and shortly afterwards, the General-Luftzeugmeister issued instructions that sufficient BV 141Bs should be delivered to form at least one operational squadron on the Eastern Front.
Plans for the Sonderstaffel BV 141 were finally cancelled by the General Staff in the spring of 1942, as, by that time, the role for which the BV 141B had been foreseen was being adequately fulfilled by the reliable twin-engined Focke-Wulf Fw 189. This decision was undoubtedly also influenced by the teething troubles being suffered by the BV 141, and a third motivation was probably the desire to ensure deliveries of the Focke-Wulf Fw 200 Condor, some 80 per cent of available Blohm und Voss assembly shop space at Hamburg-Finkenwerder having been- taken over for the Fw 200 after damage to the Focke-Wulf plant in a bombing raid. Thus, the RLM's option on a further five pre-production machines and 10 production examples was never taken up, and the peculiar BV 141 was destined never to see operational service.