B4 F.F.
The B4 over Johannisthal
Role	Light aircraft Type of aircraft
National origin	Germany
Manufacturer	Akaflieg Berlin
Designer	Walter Stender, dr. Martin Schrenk and Gerald Klein
First flight	December 1931
Number built	1

The Akaflieg Berlin B4 F.F. was a single-seat aircraft built in Germany in the early 1930s. It was a high-wing monoplane of all-wood construction with fabric-covered foldable wings^[1]

Design and development

In 1931 the Deutsche Luftfahrt-Verband e.V. (DLV) opened a competition for an inexpensive light aircraft. Two entries were put forward; Akaflieg Berlin's B4 F.F. (D-2229) and Dipl.-Ing. Hermann Mayer's MM-1 (D-2230), with both aircraft exhibited at the 1932 Deutschen Luftsport-Ausstellung (DELA) in Berlin.^[2]

Like the Mayer MM-1 the B4 F.F. was constructed at the DLV workshops in Adlershof. Design took eight months and construction a further nine.^[2]

Specifications (B4 F.F.)

Data from ^[2]

General characteristics

• Length: 5.7 m (18 ft 8 in)
• Wingspan: 9 m (29 ft 6 in)
• Height: 2.4 m (7 ft 10 in)
• Wing area: 10 m² (110 sq ft)
• Aspect ratio: 8
• Empty weight: 185 kg (408 lb)
• Gross weight: 285 kg (628 lb)
• Powerplant: 1 × Daimler F7502 , 15 kW (20 hp)
• Propellers: 2-bladed fixed-pitch propeller

Performance

• Maximum speed: 125 km/h (78 mph, 67 kn)
• Service ceiling: 3,500 m (11,500 ft)
• g limits: +8 (ultimate load factor)
• Wing loading: 28.5 kg/m² (5.8 lb/sq ft)
• Power/mass: 19.18 kg/kW (31.53 lb/hp)