Blohm + Voss BV 155

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Blohm und Voss BV 155V-2

Description
Role	Day fighter
Crew	one, pilot
Dimensions
Length	11.9 m	39 ft 4in
Wingspan	20.3 m	67ft
Height
Wing area	39 m²	384 ft²
Weights
Empty	4,868 kg	10,734 lb
Maximum take-off	5,500 kg	12,100 lb
Powerplant
Engines	1 turbocharged DB 603
Power	1180 kW	1,610 hp
Performance
Maximum speed	690 km/h	429 mph
Combat range
Ferry range
Service ceiling	16,950 m	55,610 ft
Armament
Guns	1x 30 mm MK 108 cannon 2x 20 mm MG 151/20 cannon
Bombs	none

The Blohm + Voss BV 155 was a high-altitude interceptor aircraft intended to be used by the Luftwaffe against raids by USAAF B-29's. Work started on the design in 1942, but the design went through a protracted development period for no obvious reason and was still under construction when World War II ended.

1 Background
2 Me 155B
3 BV 155A
4 BV 155B
5 Projekt 205
6 BV 155C
7 Survivors
8 External links

[edit] Background

The saga of the BV 155 high altitude interceptor actually began at Messerschmitt in the spring of 1942. At that time, it was known under the designation of Me 155, and was a company proposal for a carrier-based single seat fighter. The Me 155 was intended to be based aboard the Graf Zeppelin aircraft carrier, then under construction. In the interest of economy and simplicity, the Me 155 was to use as many Bf 109 components as possible, being basically a navalized version of the earlier Messerschmitt fighter.

The Me 155 was to be powered by a DB 605A-1 liquid-cooled engine of 1475 hp. The fuselage was more-or-less that of the standard Bf 109 G, but with an entirely new wing. The undercarrage retracted inwards into wing wells, providing the wider track required for safe carrier landings. Standard naval equipment such as folding wings, catapult spools, and arrester gear were to be fitted. Proposed armament was an engine mounted 20-mm MG 151 cannon and two 20-mm MG 151 cannon and two 13-mm MG 131 machine guns in wings. Estimated maximum speed of 403 mph.

Detail design of the Me 155 was complete by Sept 1942. However, the numerous delays in the Graf Zeppelin seemed to indicate that the launching of the carrier would be at least two years away. Messerschmitt was told to shelve the Me 155 project for the indefinite future. In the event, work on the Graf Zeppelin carrier was abandoned..

In order that all of that work on the Me 155 project not go entirely to waste, Messerschmitt adapted its design in November 1942 to match a Luftwaffe requirement for a fast single seat bomber. A single 2205 lb SC 1000 bomb was to be carried. All of the carrier equipment and most of the armament was removed from the aircraft. Additional fuel cells were provided and an elongated, non-retractable tailwheel was added to provide ground clearance for the large bomb. The proposal was designated Me 155A.

[edit] Me 155B

By the end of 1942, the increasing number of USAAF bombing raids and intelligence coming in about the new American B-29 bomber led the Luftwaffe to envisage a pressing need for an effective high-altitude interceptor. The Messerschmitt outfit adapted its design to this requirement under the designation Me 155B. The engine was to be the DB 628, which was basically a DB 605A with a two-stage mechanical supercharger with an induction cooler. A pressurized cabin was to be provided. It was estimated that a service ceiling of 46,250 feet could be attained.

A converted Bf 109G adapted to take the DB 628 engine flew in May 1942 and attained an altitude of 50,850 feet. However, the Technische Amt concluded that a DB 603A engine with an exhaust-driven turbosupercharger was more promising. The DB 603A provided 1610 hp for takeoff and 1450 hp at 49,210 feet. This engine change required that the fuselage be elongated in order to house the turbosupercharger aft of the pressure cabin. Exhaust gases were carried to the turbosupercharger via external ducts. Air was drawn in through via a ventral trough aft of the wing. Standard Bf 109G wings were to be fitted outboard of a new, long-span, untapered wing center section. Other parts were scavenged from existing Messerschmitt designs – the vertical tail was from the Me 209, and the horizontal tail and the undercarriage were taken from the Bf 109G.

In August 1943, the Technische Amt decided that Messerschmitt was over-committed, and they decided to transfer the work on the design to Blohm und Voss . After some initial study, the Blohm und Voss design team deemed that the existing Messerschmitt design had too many weaknesses. Several months of argument and finger-pointing between the Messerschmitt transition team and the Blohm und Voss designers followed. Friction between the two teams got steadily worse. In the event, no meeting of the minds was possible, and the Technische Amt eventually decided to throw Messerschmitt off the project entirely, and turn it entirely over to Blohm und Voss.

[edit] BV 155A

In September 1943 an order for five prototypes was placed. Blohm und Voss decided that the design problems still needed fixing, but by late 1943 they still hadn't been addressed. A meeting was called to finally address these problems, but the Messerschmitt people didn't bother to show up. As late as November 1943 changes were still being made, and Blohm und Voss decided to remove the complex underwing radiators favoured by Messerschmitt for two large scoop-type units mounted above the wings. B&V built a mock-up and had it tested in the LFA wind tunnel, but Messerschmitt refused to help. Late in 1943 Blohm & Voss formally advised the RLM of their problems with Messerschmitt and implored them to intervene. By this point the T-Amt was just as fed up, and removed Messerschmitt from the project entirely.

The design, now named the BV 155A, was finally completely in the hands of one design team. B&V modified the design with a completely new laminar flow wing in place of the original "extended" one from the Me 155. They also changed details of many other parts of the plane, including new landing gear (from the Ju 87) and a new tail unit. Further wind tunnel testing showed that there was a serious problem with the overwing radiators, at high angles of attack the wing "blanked" them from the airflow and cooling would suffer. The decision was made to abandon the A model completely and move on.

[edit] BV 155B

The Blohm und Voss team elected to adopt a laminar-flow airfoil section, and abandoned the idea of using standard Bf 109G wings for the outer panels. The wing center section was redesigned. Two large radiators were mounted over the wing trailing edges at the extremeties of the center section. Ju 87D-6 undercarriage legs and wheels used instead of the Bf 109G units. The Bf 109G horizontal tail surfaces were replaced with larger area freshly-designed units, and the vertical tail surface was increased in size.

The first prototype was designated BV 155 V1, and flew for the first time Sept 1, 1944. Tests with the V1 showed that the outboard radiators were not sufficiently effective in providing cooling, especially at high angles of attack. The intakes on the next prototype were enlarged and underslung beneath the wing rather than placed over it. However, the enlarged radiators caused an c.g. problem, which required moving the pressurized cockpit forward. The Blohm und Voss team took this opportunity to replace the original Bf 109G canopy with an aft-sliding all-round vision canopy, and the rear fuselage decking was cut down. This in turn required that a larger rudder be fitted. The ventral radiator bath was also enlarged.

All these changes were incorporated into the BV 155 V2, which flew for the first time on February 8, 1945. which was the first genuine B series aircraft. The Blohm und Voss team was still not satisfied with the design, and before the V-2 began its flight trials they proposed that the engine be switched to the DB 603U having the larger mechanically-driven supercharger of the DB 603E. The DB 603U promised a power of 1660 hp for takeoff and 1430 hp at 49,000 feet. The ventral turbosupercharger was retained. The Technische Amt decided to accept this proposal, and abandoned all work on the BV 155B in favor of the revised design, which was designated BV 155C.

[edit] Projekt 205

While all of this was going on, Blohm und Voss designers had been working on additional changes under Projekt 205. P.205 replaced the underwing radiators with an annular one around the front of the engine, a design feature commonly found on a number of German designs. With the wings now free of clutter, they were considerably simpler and were reduced in span. This also had the side effect of reducing the track, which would later prove to be a welcome change. The new design would be simpler, lighter and faster, and plans were made to make it the standard version of the aircraft. During the October re-evaluation, it was agreed that V-1 through V-3 would be completed as B models, while a new series of five would be completed to the new standard as the BV 155C.

[edit] BV 155C

The BV 155C was quite different in appearance from the BV 155B. The clumsy wing-mounted radiators of the BV 155B were eliminated, and the main landing gear leg attachment points were moved inboard to retract inwards. The cooling was provided by an annular frontal radiator a la Ta 152. Large circular intakes were attached to the fuselage sides above the wing roots.

In the meantime, the BV 155 V2 was damaged beyond repair during a bad landing. It was to be replaced in the test program by the BV 155 V3. The BV 155 V3 differed from the V2 in having the DB 603U intended for the BV 155C. However, the engine cowling and turbosupercharger were unchanged.

Various armament schemes for the BV 155B were proposed. One proposal had an engine-mounted 30-mm MK 108 cannon and two 20 mm MG 151/20 cannon. Another had an engine- mounted MK 103 cannon and two wing-mounted 15 mm MG 151 cannon. Estimated maximum speed was 404 mph at 39,370 feet and 429 mph at 52,490 feet. Service ceiling was to be 55,610 feet. Empty weight was 10,734 lb. Normal loaded weight ranged from 11,300 to 12,100 lb, depending on the armament provided.

[edit] Survivors

On May 3, 1945, the city of Hamburg surrendered to the British, who ordered everyone out of the Blohm und Voss plant. BV 155 V-1 was found in a flyable state, and the British brought in a pilot to fly it to England for testing. Unfortunately the aircraft encountered problems immediately and crash-landed. All the parts for the still-incomplete V-2 and V-3 were shipped to Farnborough, and V-2 was put on public display in October. There was some discussion of completing the aircraft using parts of V-3, but it was believed this did not take place, and one of the aircraft was later handed over to the U.S. The aircraft was evaluated at Wright Field near Dayton, Ohio, and was given the foreign equipment number FE-505. This aircraft was eventually transferred to the National Air and Space Museum's storage facility in Suitland, Maryland. For years it was believed that this aircraft was the incomplete V-3 aircraft, and that the British had retained V-2 for their own display, though no record of the aircraft's fate could be found. In 1998 restoration efforts by two of the NASM staff revealed that the sole surviving aircraft is in fact V-2, with some of V-3's parts applied to the airframe. It is now believed that the British attempted to restore V-2 by combining both aircraft prior to donating it to the U.S. This also explains why no record of V-3 exists after the U.S. received the aircraft.

[edit] External links

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Designation Series	Kl 152 - Ta 153 - Ta 154 - BV 155 - Fi 156 - Fi 157 - Fi 158
Related Lists	List of military aircraft of Germany