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Aviation History
1976
1976 - 1575.PDF
FLIGHT International, 21 August 1976 of an improved load distribution within the wing, maximum gross weight with tip tanks full goes to 670,0001b for an empty weight increase of only 921b. With minor changes to the wheels and tyres gross weight can rise to 690,0001b for an empty weight increase of 9001b. Extensive sideslip, engine-out and crosswind-landing tests were flown to prove the performance and structural adequacy of the enlarged rudder. The rudder has a geared anti-balance tab extending to 50 per cent of rudder chord, and the minimum control speeds demonstrated were lower than predicted. No primary structural problems were found, but some improvements were made to panel fasten ings in the fin structure. The 747SP automatic flight control system is little changed from that of the basic 747, but it does contain some system improvements. Flight-testing to Category 3a landing conditions was undertaken and all SPs incorporate the wiring so that a customer may later fit the necessary equipment. The performance of the automatic landing system was judged to be excellent and the system achieved a touchdown footprint 1,038ft long by 46ft wide (95 per cent probability) and a mean sink rate at touchdown of less than 3ft/sec. The lower sink rate results from fine tuning of the flare law and a lowering of autothrottle retard rate from 3°/sec to 2°/sec. Some 50,000 landings were simulated before actual flight-tests were undertaken and an indication of the maturity of the system is evident from the fact that no nuisance warnings or failures occurred during the test programme. A month-long world tour demonstrated the special per formance available from the 747SP. High-altitude take-offs were made from La Paz, Bolivia, the world's highest com mercial airport, 13,354ft above sea level. After take-off from Mexico City (7,340ft) SP flew non-stop to Belgrade, a distance of 6,254 n.m. Testing showed a second-segment weight-limited performance up to 40,0001b better than expected. Cruise altitudes of up to 45,000ft and a range of 7,000 n.m. with 321 passengers and baggage are SP's major selling points. In achieving that level of performance SP returns a fuel consumption about 20 per cent lower than that of a standard 747 as well as better take-off and landing performance. Compared with long-range, narrow-body types, Boeing claims, SP burns about 27 per cent less fuel per seat. A type certificate was awarded for the 747SP on Feb ruary 4, 1976, seven months after its first flight; services were inaugurated in April and 12 aircraft had been delivered by the end of July. Pan Am uses SP for very- long-range flights, notably from New York and Los Angeles to Tokyo. On May 1, Clipper Liberty Bell made a record- Below, maiden (tight of Boeing's 747SP was made at Everett on July 4 last year. Above right, Clipper Freedom, number four off the line, was the first 747SP to be delivered .•Mm\\WrtM**i Mi::!! iiit mMM fit'*! J it r ^f Ul_ •* j [ I *) ' \ > •• 'i . i •• : " t»* • - . • I. , l&igfMMr; •(. it PL i:; =i. -Hi,. U Bri mM-%) 1 Si Willi? IH13 "J; ffl '•!: K¥i I 'ill M\XK i ikPR :li'lK 423 \£7£r£FS/y£ mmmemmmmiam ^"=4.1 iMISBBS HS' \\ Lfii'p breaking round-the-world flight, JFK to JFK in 46hr 50sec with only two stops on the way—Delhi and Tokyo. South African Airways, the second SP customer, prefers to use the SP where the regular 747 is too- big—roughly the same market as could be filled by the wide-body trijets —and the range is slightly too great for the DC-10-30. In that role Boeing claims SP direct operating cost roughly equal to that of the trijets. Pan Am has absorbed five SPs into its 747 fleet and the same pilots fly both types. Long-range flying usually enhances utilisation figures and SP is continuing this trend. Up to mid-July Pan Am achieved 10-9hr each day and this month it plans a utilisation of 13-8hr per day. Despatch reliability taken over 418 departures stands at 96-9 per cent. The American flag carrier now offers a daily non-stop New York-Tokyo flight. Services started on April 26 with three flights a week and in the first month passenger loads per trip averaged 150 westbound and 200 eastbound Los Angeles-Tokyo is also a daily service and is recording high load factors. Japan Air Lines flies DC-8-62s on a daily service between Tokyo and New York via Anchorage and admits to losing some passengers to Pan Am. Although PAA has almost trebled its passenger loads, the airline says that new traffic has also been generated. A survey of 513 frequent travellers living in Tokyo and Osaka showed that a quarter were willing to delay their departure by up to 24hr in order to fly non-stop to the USA, The result is particularly signifi cant in view of the Japanese travellers' known allegiance to the national carrier. South African Airways is recording good load factors between Johannesburg and Europe and Iran Air, the third SP customer, is reporting a 90 per cent load factor on its non-stop New York-Tehran route. Towards the end of June Syrian Air introduced SP between Damascus and London Like SAA, it is using 747SP because the standard 747 is too big for the route. The very long ranges offered by SP have introduced new operational techniques and crew-management prob lems (see Flight for June 26, page 1692). Pan American now carries only one additional pilot instead of the full additional crew that it carried earlier and cabin attendants are able to relax in turn during the quieter times of the flight. The 8,000ft cabin altitude and long flight times have led to complaints of dehydration and difficulty in breath ing. An additional circulation fan aft has helped a lot and passengers are encouraged to take soft drinks frequently. Passenger reaction to long distance non-stop flying is very good, most saying that they prefer to get it over with as quickly as possible rather than take the extra two or three hours needed on a one-stop service.
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