National Geographic : 1933 Aug
THE AERIAL CONQUEST OF EVEREST on the windward side of the mountain. No one could forecast the strength of these, which might well be terrific; so that 1,350 foot margin was all there was to save the machine from being beaten down by the im mense wind forces onto those terrific cliffs. Therefore the extra 500 feet of ceiling which the inclosing of the cockpit offered us might make all the difference between suc cess and disaster. We constructed a roof with double flaps hinged along the sides of the fuselage, so that they could be folded down inward after the completion of the climb to allow the observer to put his head and shoulders out side. These flaps had transparent celas troid windows, and the arrangement worked excellently. Next came the electrical installation. This was essential to the lives of pilot and observer, not merely in order to heat their clothing, but still more to supply current to the oxygen heaters. Unless the life-giving gas were heated, it might freeze solid in its tiny orifices of issue. In that event the pilot would lose consciousness in 35 seconds. In a flight over level country he might possibly recover after the machine had swooped down out of control for ten or twenty thousand feet. Over the mountains there could be no such hope. Thus the electrical supply was vital. Its planning was hedged round by special dif ficulties. A dynamo was necessary, and it is the usual practice to have this driven by a windmill. But a windmill would not act at the great heights unless specially de signed, of enormous size and thus of corre sponding weight and "drag." Soithadto be driven by a gearing from the engine. Fresh difficulties cropped up. No such large dynamo as we required had ever been installed; so special gears had to be de signed and embodied. Next a battery was needed as a stand-by; but accumulators have the idiosyncrasy of giving no current in great cold. So the battery had to be packed about in felt and much trust placed in the interposition of Providence to save it from a chill. In actual reality, all de pended upon the single dynamo, which rose nobly to the occasion. The current had to go through two heated suits, two pairs of boots and gloves, and even through both pairs of goggles, which were warmed by tiny hot filaments cleverly inserted between two thin sheets of triplex glass. Not less important was the warming of the many cameras which were to be carried and of their spare films. One of our diffi culties was that celluloid film, when frozen, becomes brittle and flies to pieces if one attempts to bend it. Of our eight cameras, three cine cameras and two survey cameras depended on this celluloid film. Here we met with difficul ties that were almost heart-breaking. The films and the mechanisms proved tempera mental to the last degree. Nor was it an easy matter on which to experiment. The airplanes had to be packed and shipped al most as soon as they were ready; so that tests in actual high flights could only be brief. So we arranged with the leading British firm of refrigerating engineers, Messrs. Hall of Dartford, who most kindly fitted up a special chamber affording the extremely low temperatures down to minus 60 degrees centigrade-that is, 76 degrees below zero, Fahrenheit-which we needed. This was most costly to keep chilled for any long period; so tests, however vital, were neces sarily hasty. At length we made everything work, but only just in time. FORTIFYING CAMERAS AGAINST EXTREME COLD Each of the eight cameras was provided with either internal heating elements or with a padded fabric jacket with heating wires sewn into it, similar to those in the suits (see illustration, page 142). Not only did each camera, but the spare magazine for each survey camera and the spare spools for the cine cameras, call for heated jackets as well. Fortunately, the oblique cameras were a simpler problem, using plates; but it will be realized that each camera needed a flexible cable to be led to it, and the multiplicity of these in the cockpit formed a veritable spider's web. To prevent the many leads getting tan gled with oxygen pipes, connections for heated clothing, and with telephone leads was a formidable problem for the observer, hampered by the huge bulk of his suit. At last all was reasonably ready on the very eve of the day on which the ship sailed; but, even so, many details remained to be completed in India. We carried out acceptance flights in which machines and engines performed admirably, giving more height than their designers had originally promised.