Glossary — B

B Bomber (US designation prefix).

BAC British Aircraft Corporation.

BAe British Aerospace.

ballistic parachute Emergency recovery parachute installed in (generally light) aircraft and capable of supporting both machine and occupants.

band See radar frequency.

bar Non-SI unit of pressure adopted by this yearbook pending wider acceptance of Pa. 1 bar = 10⁵ Pa. ISA pressure at S/L is 1013.2 mb or just over 1 bar. ICAO has standardised hectopascal for atmospheric pressure, in which ISA S/L pressure is 101.32 hPa.

basic operating weight MTOW minus payload (thus, including crew, fuel and oil, bar stocks, cutlery and so on).

BBMF Battle of Britain Memorial Flight.

Be Beriev (Russian design bureau).

bearingless rotor Rotor in which flapping, lead/lag and pitch change movements are provided by the flexibility of the structural material and not by bearings. No rotor is truly rigid.

BERP British Experimental Rotorcraft Programme.

BITE Built-in test equipment.

bladder tank Fuel (or other fluid) tank of flexible material.

BLC Boundary-layer control.

bleed air Hot high-pressure air extracted from gas turbine engine compressor or combustor and taken through valves and pipes to perform useful work such as pressurisation, driving machinery or anti-icing by heating surfaces.

blown flap Flap across which bleed air is discharged at high (often supersonic) speed to prevent flow breakaway.

BOW Basic operating weight (which see).

BPR Bypass ratio.

BTU Non-SI energy unit (British Thermal Unit) = 0.9478 J.

bulk cargo All cargo not packed in containers or on pallets.

bus Busbar, main terminal in electrical system to which battery or generator power is supplied.

BV Besloten Vennootschap (Netherlands company constitution).

BVR Beyond visual range.

BWB Blended wing/body.

bypass ratio Air flow through fan duct (not passing through core) divided by airflow through core.

byte Group of bits of information forming unit in computer processing.