BAC 221 Fairey Delta 2

bac 221 @ fleet air arm museum. forward extension , general curving layout can seen

low-speed testing of concept being provided handley page hp.115. although high-speed performance appeared predictable, dedicated testbed aircraft desired, drag measurements. 1958, rae , fairey began discussions converting 1 of delta 2 prototypes support ogee wing. fairey proposed stretching fuselage further 3 feet better match long planform, wing extending out onto drooping nose. however, calculations showed extension not great enough counter forward moving centre of pressure (cop) resulted extended planform, , there concerns over-wing engine intakes swallow vortex above wing.

during 1960, further development activity disrupted purchase of fairey westland aircraft, assigned further work on conversion project hunting aircraft. accordingly, in july 1960, programme moved bristol , part of larger british aircraft corporation (bac). bristol suggested 2 ways forward, minimal conversion sub-optimal wing no other major changes, or maximal conversion larger 6 foot extension fuselage , taller landing gear more typical of type expected on concorde. both equipped new elliott brothers stabilization system, , have engine intakes moved under wing. minimal conversion considered more of compromise , being less slender , lacking additional fuel capacity maximal option provided for.

in september 1960, agreed maximal conversion proceed; on 5 september of year, wg774 flown bristol s filton facility. following period of detailed design work, re-manufacturing process commenced in april 1961. considerable cost cutting measures , management strategies, such pert, adopted bac in order not overrun on fixed-price contract had been issued work; engineers allegedly frustrated apparent means of further improvement dismissed. on 7 july 1961, newly christened bac 221 completed.

several problems encountered during conversion. newly lengthened landing gear required more hydraulic fluid, required larger reservoir hold it, pump move enough through system, , on through hydraulic system. retaining relatively simple intakes on bottom of wing presented issue airflow engine below, opposed entire compressor face, ducts extended above wing split airflow evenly; produced noticeable bulge on upper surface of wing. no attempt made fit variable intakes. @ high throttle settings, considerable suction inlets generated; in event of sudden down-throttle motion pilot result in air spilling out of intakes, concern because flow above wing , disrupt vortex. small lips added intakes prevent this, proved cause intake buzzing. changes ducts, assisted rolls-royce, addressed issue.

one major advantage of new design larger fuel capacity, has been major problem original fd2. delta 2 had run out of fuel while still accelerating, thereby never reaching full performance. modifications 221 meant not capable of same levels of performance; however, speeds of mach 1.6 attained during test flights. in total, bac 221 featured new wing, engine inlet configuration, rolls-royce avon ra.28, modified vertical stabilizer , lengthened undercarriage mimic concorde s attitude on ground. first flew in form on 1 may 1964. sole 221 used various test flight conducted 1964 until 1973, after aircraft after preserved , placed on public display.