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Aviation History
1960
1960 - 0073.PDF
73 FLIGHT, 15 January] 1960 (Left) White paint and sunshme at DaKar while we wait for nightfall and the South Atlantic crossing to Brazil. (Right) Below is Santiago, overlooked by the snow-topped Andes. We climb to 30,000tt overhead before setting course for home Nine Days to Christmas . . . tingencies, deviations from forecast winds and so on) and a further2,500kg "station contingency" fuel to cover holding, descent, a circuit and landing and 500kg residual fuel in the tanks. This2,500kg varies from station to station; at Santiago for instance, where the Andes necessitate a descent from almost directly over-head, it is considerably increased; at London it can be reduced. Minimum reserve is uplifted at the commander's discretion;normally more fuel will be taken on board if the payload, weather or fuel price warrant it. Translating this quantity into gallons isthe responsibility of the flight engineer, who compiles a fuelling record which gives the fuel required in gallons after correctionfor density of that in the bowser. Residual fuel in the aircraft must also be density-checked, and on each refuelling stop it isone of the engineer's duties to check a hydrometer reading of the fuel bled off from the dripsticks, correct for density and calculatethe total fuel required. Very soon after take-off the Comet must be throttled back toprevent exceeding the maximum permissible i.a.s. before the flaps and undercarriage are raised. Our aircraft, equipped with Avon524Bs and thrust reverse has available 8,050 r.p.m. for take-off and we climb at 260kt i.a.s. at 7,350 r.p.m. to 30,000ft. This is theheight at which a constant-i.a.s. climb is abandoned for a climb at constant Mach number and from here up to the cruising heightwe maintain M0.7, the i.a.s. reducing by 4kt for each additional 1,000ft of height. There are three cruising techniques for the Comet: corporationpolicy is to use the best-economy cruise at M0.73 (1.15 X minimum drag speed) but there is also a high-speed technique at 1.2 Vm<iand a Mach number of 0.75, while for maximum range the aircraft is flown at a Mach number of 0.69 (1.06 Vmd). Ideally, cruisingaltitude should be kept within limits of about + 500ft but if air traffic control demands a departure from the ideal height for theparticular weight, either the cruising Mach number must be reduced if the altitude is too high, or a level-cruise techniqueat M0.69 can be adopted if it is too low. The other alternative in the latter case is simply to accept the fuel penalty involved. Because fuel consumptions can be approximately gauged it iseasy enough to estimate the height at which the Comet must be levelled off, but towards the top of the climb the flight engineerwill prepare a "top of climb" weight statement from which the correct cruising altitude can be more closely determined. Whenthis altitude is reached the height lock on the autopilot is plugged in and the aircraft is allowed to accelerate on climbing poweruntil the correct Mach number is reached. At this speed the autopilot is transferredTrom height lock to speed lock, powerreduced to between 6,800 to 7,100 r.p.m. (depending upon the outside air temperature) and the aircraft allowed to drift up inits cruise climb through about 300ft to 400ft every 15 minutes. Briefly, r.p.m. depends upon temperature and altitude dependsupon weight, so that as the weight is reduced during the cruise —it drops about 1,000kg every 15 minutes—the airspeed isadjusted and the height is checked. The flight engineer is occupied during the climb with the fuelconsumption and weight statements which are passed forward about every 12 minutes; each takes about five minutes to com-plete. After the climb, fuel-flows stabilize at under l,000kg/hr, dropping to 600kg/hr as weight is burnt off, and during thecruise a weight statement is then completed at intervals of about half an hour. From these statements the navigator completes arunning Howgozit chart showing how fuel actually used has compared with that estimated for the climb and cruise climb,and time early or late at the various reporting points. In the intervals between complete fuel statements the engineeris monitoring the panel and logging the readings—a check on instantaneous observations and a good guide to a drift in thereading of any instrument. About 150 n.m. from destination the inboards are brought backto ground idle and r.p.m. on the outers adjusted to establish an indicated airspeed of about 220kt. The average rate of descentis then about l,200ft/min; speed brakes are not normally used, as a clean aircraft gives the best economy; but in practice they are employed as the occasion demands. They increase the rate ofdescent to 3,000ft/min. We are given a good illustration of this while descending intoDakar; after a long, smooth descent from the 37,000ft reached on the cruise-climb we use airbrakes to steepen the descent into thehaze over the narrow neck of land that is Dakar. A surprise here is two airfields, one small with dark runways, the other new andmuch larger, with concrete runways over 9,000ft long. We take a good look at it as we sweep over the old airfield, but no in-formation about it was available before we left London and it is only on landing that we find that Air France Boeing 707s havealready used it for demonstrations. By January 25, when services start, it should be available for BOAC's Comets. A hot afternoon in Dakar is occupied with another two demon-stration flights for the duty crew and with sightseeing for the passengers—the latter escorted by a friendly and knowledgeableGambian guide. There is no great urgency to leave; aids are few over the South Atlantic and the schedule determines that thecrossing be made at night, using the mariner's centuries-old aids of dead reckoning and astro-navigation. As we head westward the darkness begins to overtake us; thegreat cloud-masses of the intertropical front converge on every side and grey cloud fingers stretch above us to the lonely heights. Soon we are experiencing what crews refer to as "meal-timeturbulence," the bumpy ride that frequently seems to accompany the serving of dinner. With the scanner undepressed, the radaris indicating a solid front of cloud, and we divert slightly to avoid it. Four and a half hours after leaving Africa we are touching downin South America—at Recife, Brazil, hot and tropical even in the evening air. Clambering down the unlit steps into the darknesswe trail unescorted across the apron towards the terminal, sud- denly to be confronted with a Panair do Brasil DC-7C set upontaxying across the same stretch of concrete. It switches on its landing lights and stops, but not before the crocodile of Cometpassengers has split up in alarm. Fourth Day. Recife - Montevideo. To the dismay of theBrazilian journalists on their way home, the cloudbase is well below the 1,000ft minimum required for a let-down on the oneNDB which is Sao Paulo's solitary aid, and we fill up with 30,000kg of Querosene (the local brew) to overfly to Montevideo.This is our heaviest load yet and it brings us to maximum weight for take-off. For this leg I am invited—provided I make myselfsufficiently inconspicuous—to watch part of the flight from the cockpit. There is not much room to spare; but, astonishingly,eight of us manage to squeeze in to see the take-off: Captains Beauchamp and Moore in the front seats; a third pilot on oneedge of the jump seat; a flight engineer under training at the engineer's panel; a qualified engineer behind him; a BOAC com-munication's engineer listening in to the R/T; and Capt Millichap, there to check the operation in his capacity as commander. Refreshing cologne-soaked towels come forward from thegalley; the Comet is hot after hours in the sun. Checks com- pleted, engines are started and we taxi to the end of the runway.It is hot and we are heavy, and Capt Beauchamp gets full thrust from the Avons before he releases the brakes. We use 6,900ftof runway but, as always, the Comet makes light work of the take-off. Capt Moore calls Vi at 109kt, V2 at 122kt, then the nosevibrates as the gear comes up and we climb steeply away, receiving Speedbird Jet 010's climb clearance on 190 deg as we go."True or magnetic?" we query Recife repeatedly, but the question seems not to be understood.From Recife down to San Salvador, one of our reporting points, we have a choice of three different operating heights on the red,green or amber airway but we ignore them all and set course for Uruguay direct. Navigation over this sector is by dead reckoning,but ADF is used to pick off the NDBs at San Salvador and Porte Allegre and HF for communication with Recife and Salvador,who are relaying to Montevideo our request for terminal weather. We receive all HF transmissions with a background of music, andenjoy snatches of catchy South American dance rhythms 36,000ft above the South Atlantic. The music and the radio provide the pilots with a new source
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