National Geographic : 1906 Apr
THE NATIONAL GEOGRAPHIC MAGAZINE AIRSHIP VOYAGES BY ANALOGY In his studies of the fascinating prob lem of the best means to adopt for reach ing the North Pole in a dirigible, Mr Wellman hit upon the idea of writing up the log of his aeronef throughout a num ber of test voyages, assuming that the winds throughout each voyage were the same as those which prevailed at the Fram. Accordingly, he named eight dates, somewhat at random, but corre sponding generally to the date on which it is expected his trip may be made from Spitzbergen toward the Pole-the latter part of July and early days of August. These dates will be found on the next page. The motor speed of the dirigible is assumed at 12 miles (geographical) per hour. The maximum retardation by the dragging anchor in adverse winds is as sumed at 12 miles per hour. Allowance is made for the effect of all winds oblique to the course. For example, in voyage B, from Io p. m. to midnight, July 25, the wind was SW. at 12 miles per hour, and one-half of its movement, or 12 miles for the two hours, is assumed as the "north ing" effect upon the airship. The start from Spitzbergen is made in the first southerly wind that blows on or after the first of the days named in each of the periods, chosen arbitrarily. Thus the log is written up hour by hour from the Fram records, following the method of navigation already described by Mr Wellman in the foregoing pages. It will be remembered that Dr Nansen's ship, the Fram, drifted for three years through the Arctic Ocean, traversing in part the very region the Wellman air ship is planned to sail across. As Mr Wellman points out, no one can know that the winds which his airship encoun ters on its actual voyage are to be like those of any one of these Io-day Fram records. But it is only reasonable to as sume that they will not be widely differ ent, probably not much better, probably not much worse. In the most favorable of these exam- ples the vicinity of the Pole is reached in 28 hours. In the most unfavorable it is reached in 152 hours, of which 68 hours are given to work with the motors and 84 hours to drifting with the retardateur. Inasmuch as it is believed the aeronef can remain in the air from 12 to 20 days, and the fuel supply carried is equal to about 140 hours' motoring, it will be seen that even in this case of the most contrary winds only one half the radius of the airship is consumed in attaining proximity to the Pole. It should also be borne in mind that an essential feature of the expedition plan is to carry a complete sledging equipment, with motor-driven sledges, etc., and pro visions for 75 days, so that in case the air ship should fail through any cause, its crew could resolve themselves into a sledging party and continue their work of exploration or make their way back to the nearest land. The temperature is not an obstacle to the success of the expedition, as it ranges, during July and the first half of August, about the freezing point, rarely going more than a few degrees above or below zero centigrade. The temperature in the Arctic Ocean in summer is the most con stant to be found anywhere on the sur face of the globe, and this is a great ad vantage in aeronautic work, as the gas is subjected to the minimum of dilatation and contraction. In his studies Mr Wellman has taken account of all other conditions, such as the precipitation of snow, rain, or sleet, which may weigh down the airship, and he has made provisions to meet and over come this difficulty. Mr Wellman concludes with the pru dent observation that these analyses do not show that he is certain of attaining the Pole by airship, but that they do in dicate ground for a reasonable amount of hope and demonstrate that the expe dition is planned on a practical and even promising basis. 224.