The Blohm & Voss BV 155 was a German high-altitude interceptor aircraft intended to be used by the Luftwaffe against raids by USAAF Boeing B-29 Super fortresses.
Work started on the design as the Messerschmitt Me 155 in 1942, but the project went through a protracted development period and change of ownership and prototypes were still under test and development when World War II ended.
Performance estimates of the American B-29 Superfortress reached German command in early 1942.
The bomber would cruise at an altitude at which no current German plane could operate effectively.
To intercept it, the Luftwaffe would urgently need new aircraft.
Work on such a high-altitude fighter was begun by Messerschmitt, but in 1943 the project was passed to Blohm & Voss.
The result would be the Bv 155 prototype that made its first test flight in September 1944.
In September 1943, an order for five prototypes was placed. Blohm & Voss accepted the order only on condition they had complete design freedom and were not bound by Messerschmitt’s work to date.
The redesign was named the BV 155.
B&V gave it a new laminar flow wing and tail unit, landing gear from the Ju 87 and many other parts of the plane.
Further wind tunnel testing showed that there was a serious problem with the over wing radiators, at high angles of attack the wing “blanked” them from the airflow and cooling would suffer.
Work moved to a revised B model.
The first prototype, BV 155 V1, took off for its maiden flight on September 1, 1944.
Tests with the V1 showed that the outboard radiators provided inadequate cooling, especially at high angle of attack.
The intakes on the next prototype were enlarged and under slung beneath the wing rather than placed over it.
However, the enlarged radiators changed the aircraft’s centre of gravity which required moving the pressurized cockpit forward.
The Blohm & 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.
With these changes, the BV 155 V2 flew on February 8, 1945.
Blohm & Voss was still not satisfied with the design, and before the V2 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 1,238 kW (1,660 hp) for take-off and 1,066 kW (1,430 hp) at 14,935 m (49,000 ft).
The ventral turbosupercharger was retained.
The Technische Amt decided to accept this proposal and abandoned all work on the BV 155B in favour of the revised design, which was designated BV 155C.
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 (1.18 in) MK 108 cannon and two 20 mm MG 151/20 cannons.
Another had a Motorkanone mount 30 mm (1.18 in) MK 103 cannon and two wing mounted 20 mm MG 151 cannons.
Estimated maximum speed was 650 km/h (400 mph) at 12,000 m (39,370 ft) and 690 km/h (430 mph) at 15,999 m (52,490 ft).
Service ceiling was to be 16,950 m (55,610 ft). Empty weight was 4,869 kg (10,734 lb).
Normal loaded weight ranged from 5,126-5,488 kg (11,300-12,100 lb), depending on the armament provided.
According to the Pegasus Models Kit No. 5002 information sheet, V1 and V2 were both provided to the RAF after the war.
V1 was flight-tested until it was written off.
The fate of V3 is not known, except that it was left half-finished by the end of the war.
V2 is in storage at the Smithsonian’s National Air and Space Museum’s storage facility.
In parallel with the prototype development, Blohm & Voss had been working on additional changes under Project 205.
P.205 replaced the under-wing 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 V1 through V3 would be completed as B models, while a new series of five would be completed to the new standard as the BV 155C.
The BV 155C was to be significantly 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.
Cooling was provided by an annular frontal radiator as in the Focke-Wulf Ta 152.
Large circular intakes were attached to the fuselage sides above the wing roots.
Specifications
(BV 155B)
Crew
1
Length
12 m (39 ft 4 in)
Wingspan
20.5 m (67 ft 3 in)
Height
3 m (9 ft 10 in)
Wing area
39 m2 (420 sq ft)
Empty weight
4,870 kg (10,737 lb)
Gross weight
Proposal A
5,520 kg (12,170 lb)
Proposal B
5,125 kg (11,299 lb)
Proposal C
5,100 kg (11,244 lb)
Proposal D
5,440 kg (11,993 lb)
Max take-off weight
6,020 kg (13,272 lb)
Fuel capacity
1,200 l (264 imp gal)
Powerplant
1 × Daimler-Benz DB 603A,
Inverted V-12 liquid cooled piston engine with TKL 15 turbocharger,
1,200 kW (1,600 hp) for take-off
1,200 kW (1,609 hp) at 10,000 m (32,808 ft)
1,081 kW (1,450 hp) at 15,000 m (49,213 ft)
Propellers
4 bladed constant speed paddle bladed propeller
Performance
Maximum speed
420 km/h (260 mph, 230 kn) at sea level
520 km/h (323 mph) at 6,000 m (19,685 ft)
600 km/h (373 mph) at 10,000 m (32,808 ft)
650 km/h (404 mph) at 12,000 m (39,370 ft)
690 km/h (429 mph) at 16,000 m (52,493 ft)
Range
460 km (290 mi, 250 nmi) at maximum continuous power with 595 l (131 imp gal) of fuel at sea level
560 km (348 mi) with 595 l (131 imp gal) of fuel at 10,000 m (32,808 ft)
590 km (367 mi) with 595 l (131 imp gal) of fuel at 16,000 m (52,493 ft)
1,080 km (671 mi) with 1,200 l (264 imp gal) of fuel at sea level
1,350 km (839 mi) with 1,200 l (264 imp gal) of fuel at 10,000 m (32,808 ft)
1,440 km (895 mi) with 1,200 l (264 imp gal) of fuel at 16,000 m (52,493 ft)
Service ceiling
16,950 m (55,610 ft) service ceiling
Maximum ceiling
17,100 m (56,102 ft)
Rate of climb
11.5 m/s (2,260 ft/min) initial
3.92 m/s (13 ft/s) at 16,000 m (52,493 ft)
Time to altitude
16,000 m (52,493 ft) in 29 minutes
Armament
Guns
Proposal A
1 × 30 mm (1.181 in) MK 108 cannon as an engine mounted Motorkanone firing through the propeller shaft
2 × 20 mm MG 151/20 cannon
Proposal B
1 × 30 mm (1.181 in) MK 103 cannon as an engine mounted Motorkanone firing through the propeller shaft with 60 rounds
2 × 15 mm (0.591 in) MG 151 cannon with 200 rpg
Proposal C
3 × 30 mm (1.181 in) MK 108 cannon with 60 rpg.
Proposal D
3 × 30 mm (1.181 in) MK 103 cannon with 60 rpg (two mounted in under-wing fairings).
