FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1949
1949 - 1993.PDF
PLIGHT, 15 December 1949 •759 Modifications apparent in these views of the newCentaurus 661 installation include the smaller spinner, without cooling fan, and altered intakedesign. Exceptional!/ good access to the Ambas- sador power-plant is given by the " petal " or"clover-leaf" type of cowling. AMBASSADOR PROGRESS Testing of Wing Structure and Pressurization : Engine Development SUCCESSFUL completion at Farnborough, 011 December6th, of the third strength-test of the full-span Ambassadorwing specimen, marked the completion of a progressive year of testing the design and construction of the whole Air- speed aircraft. The wing stood up to the target loading of 100 per cent—with an effect equivalent to a 50 ft/sec up-gust on the fully loaded aircraft at cruising speed—and ultimately failed at 120 per cent. Exceptionally consistent standards of workmanship andmaterials are indicated by the fact that failure took place simultaneously, and at the same point, on each outer wing.When the 100 per cent loading was attained, a technical fault in the recording circuit occurred, and the wing specimen wasleft in this highly stressed state for 18 minutes before the test was continued—a further impressive proof of the integral solid-ity of the structure. Since the previous test a number of modifications had been made to the wing; the gain in strengthhad been approximately 40 per cent for a corresponding weight increase of only 280 lb. The basic design of the wing has notbeen altered in any way. In the test, the R.A.E. made use of electronic strain-gauging equipment, developed by the Airspeed research department andknown as the Polygraph recorder, which gives immediate and continuous readings.The Ambassador pressurization system has been the subject of another important item in the development programme. Thecontrol-cabin, windows and detail structure have been checked in one fuselage test-specimen, the centre-section area and com-plete fuselage aft of the control-cabin bulkhead in another. The specimen used for the latter test was submerged in a dockat Portsmouth and pressure-filled with water, dyed a deep blue : the colour enabled leaks to be detected immediately. (Sincewater is virtually incompressible, the pressure-energy stored in it is very small and is almost instantaneously released wheninitial failure occurs; the area of subsequent secondary failure is thus reduced to a minimum.) Testing gave satisfactory re-sults. The frontal section (tested at de Havilland's) withstood 9.9 lb/sq in and the complete specimen, at Portsmouth (illus-trated on p. 757), failed at 9.8 lb/sq in. Normal operating pressure differential of the Ambassador will be 4.16 lb/sq in.Airspeed's pre-production programme is now well under way. A pre-production aircraft is due to be delivered to B.E.A. nextMarch, and will be used—fully furnished—for route surveys. Delivery of the complete batchshould begin in January, 1951, and be completed by the end of that year. Ambassadors for B.E.A. will have Centaurus661 engines of 2,700 b.h.p. for take-off, as com- pared with the Centaurus 631s at present installedon the first two prototypes. A mock-up and a test- mounting for the 661 have been constructed atChristchurch, and the first prototype (G-AGUA) is at present undergoing fitment of a 661 in the portnacelle, the starboard 631 being retained. The mounting of the Centaurus 661 differs con-siderably from earlier versions, the cooling fan having been removed, a smaller spinner incorpor-ated and a combined oil-cooler and twin air-intake fitted underneath. Particular attention has beenpaid to maintenance, and the power unit now has a neat four-piece "petal" cowling, providinggreater access. On G-AGUA the Centaurus 661, with torquemeter, will provide a direct compari-son with the 631, and the merits of the cooling systems will be tested. An Ambassador interior mock-up, showing thestandard B.E.A. seating arrangement. Three seats are placed on one side of the gangway,two on the other.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
