FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1955
1955 - 0068.PDF
68 FLIGHT, 21 January 1955 BRITANNIA DEVELOPMENT ACCELERATES Night-and-Day Flying Programme Under Way at Filton IN preparation for its introduction to service with B.O.A.C.,the Bristol Britannia 100 is to undergo a flight-test ofunprecedented intensity. News of this programme has just been announced by the manufacturers, who, contrary to earlier plans, will not now deliver aircraft to the Corporation until the type has been awarded its full Certificate of Airworthiness. Originally it was intended that B.O.A.C. should take deliveryof the second, third and fourth aircraft almost immediately after their initial flight tests. These Britannias, with a restricted C. of A.permitting regular flights overseas but not the carriage of fare- paying passengers, would have been used for crew training androute proving, and for building up the amount of pre-service type experience required by the A.R.B. as a precautionary measure. As things now stand, Britannias should reach B.O.A.C. withfull clearance to carry passengers on regular services on com- pletion of the normal "working-up" period of route-flying andtraining. The Bristol programme, in which three B.O.A.C. crews arc taking part, calls for the completion of the entire Britanniaflight-development schedule, including C. of A. tests, by mid- 1955. Four aircraft should by then have logged 2,000 Britanniahours additional to those flown before the present programme began. Meanwhile, a Britannia 100 "specimen", a composite struc-ture built up from the most advanced wing and fuselage com- ponents available from the production line, is being prepared forwater-tank testing by the R.A.E. at Farnborough. These trials, which are designed to establish the safe fatigue-life of the pressurecabin, will begin in late February or early March. The pressuriza- tion cycle will be repeated 1,000 times weekly, 1,000 cycles beingequivalent to some 4,000 flying hours. The requirement for similar tests on the Britannia 300 is, incidentally, being anticipatedby the construction of a tank at Bristol's Filton works. At January 13th, Britannia flight time stood at 768 hr 30 min,including 51 hr 10 min logged by the second prototype, G-ALRX, before its forced landing last year. Details of the past and futureflying programmes of other Britannias are as follows: — G-ALBO (first prototype), 442 hr 45 min at January 13th. Thisaircraft- will handle the bulk of the flying programme at a target rate of 150 hours monthly, this total being based on a "super-target" of 264 hours—Le., a theoretical maximum of two six-hour flights between 8 a.m. and midnight on 22 days of each month.G-ANBA, the first production Britannia 100, had flown 274 hr 35 min by January 13th. It is scheduled to fly 75 hr monthly underthe new programme. G-ANBB has just been completed, and will almost certainly have flown by the time these words appear; itis scheduled to fly 50 hours monthly. G-ANBC, the third pro- duction aircraft, should be flying within the next two or threemonths. It will contribute some 250 hours of route-proving flights to the development programme. G-ALBO will, in the course of the next few months, providevaluable experience of the Britannia's response to a "commercial" rate of utilization. This applies equally, of course, to its Proteus705 turboprops and D.H. hollow-steel airscrews. In addition, vibrograph recordings made in turbulent conditions will furnishbasic data for the tank-test at Farnborough. The first production aircraft, G-ANBA, will be used for C. ofA. trials, including some performance measurements and the de- icing programme. Part of Britannia's de-icing system has beenproved on a Varsity test-bed, and the amount of work remaining is not considered to be extensive. There is no questionof making numerous extended flights in search of heavy-icing conditions. G-ANBB will be employed largely on handling tests—another phase of the C. of A. programme. This aircraft em- bodies the minor control modifications made as a result of earliertests, and is fitted with stall-warning indication. The third pro- duction aircraft will embody these and all other modifications,enabling it to be offered to the Air Registration Board as a fully representative Britannia for the final phases of certification. Engine hours accumulated during the Britannia programme willobviously far outnumber those obtained with the Proteus- Ambassador test-bed. Use of this aircraft, however, will permitconcentration on particular aspects of power-plant behaviour without holding up the main airframe-engines-systems pro-gramme. It is now proposed, for example, to study engine icing characteristics with the aid of TV equipment for in-flight observa-tion. Completion of the present development programme should take the Proteus flying-hours total past the 11,000 mark, in addi-tion to the 25,000 hours' bench-running already completed. In charge of the Britannia's intensive flying programme isBristol's chief test pilot, Mr. A. J. ("Bill") Pegg. Following a call on Mr. Pegg at Filton last week, we can add fresh detail to thisoutline of the work now being performed by the Bristol-B.O.A.C. development team, which is already operating, like a small airlineunit, on a dawn-to-midnight basis. The weather problem has been overcome by the acquisition ofa Decca 424 radar, which enables test aircraft returning from long flights to be talked down without delay. The weather minimaapplied are 300ft cloud base and 1,200 yd visibility; diversion has not yet been necessary. When we visited Filton the Decca hadbeen in use for a month, and over that period, said Mr. Pegg, "It has given us 50 flying hours we should otherwise have lost." Full tropical trials will be made with G-ANBA—probably inFebruary, though the exact date of its departure has not yet been announced. High-altitude performance measurements will bemade first at Johannesburg, and these will be followed by high- temperature trials at Khartoum. The amount of preparation involved by long overseas excur-sions with new aircraft is not widely appreciated. The "prelimin- ary canter" to Idris, Tripoli, last October was intended partlyto uncover any unexpected problems which might otherwise have prolonged or caused postponement of the trials proper. In theevent, the aircraft behaved well and its measured performance corresponded to a remarkable degree with the estimates of Bristol'sanalysts. In preparation for the high-altitude tests, full-weight take-offs have been made at Filton on the power which will beavailable at Johannesburg. The permitted gross weight of the Mk 100 Britannia has beenincreased to 150,000 lb, and the aircraft has frequently been landed at weights approaching 140,000 lb—the original gross weight. Performance calculations have proved so accurate that, to quoteBristol's chief pilot, the Britannia can be flown "from the brochure." During the recent flight to Idris the aircraft cruised,under optimum conditions, at 374 m.p.h. T.A.S.—2 m.p.h. above the predicted performance. Cabin pressurization is used whenever possible; on occasions, The Britannia prototype, shown being prepared for a night flight horn Filton, is now engaged in a development programme without precedent in commercial aviation. Two aircraft—G-ALBO and G-ANBA— recently logged a combined total of 24 hours' test flying in one day.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
