CHAPTER VIII
THE Ocean Flyer CREW IS COMPLETED
Before the arrival of the big automobile, Ned and Alan had a conference with the man in the rear room on the first floor. In all their aeronautical experience, one constant annoyance had been their inability to estimate exactly the speed at which they were traveling. Advancing either with or against the wind—which is always in motion a few hundred feet above the ground—they always had to take the readings of the anemometer with allowances. With the airship speeding into the wind, the pressure set up by the aeroplane itself was increased by the force of the encountered wind. The flight of a balloon directly upward is accurately determined by the barometer. But the drift of a dirigible is largely a matter of judgment or deduction from the anemometer readings.
Because of this the boys had been utilizing the reserve monoplanes of the Universal Transportation Company and some of the lighter, standard aeroplanes of the manufacturing company, to make experiments in flight speed and how to determine this speed with exactness. Alan, the mathematician of the young partners, had made deductions based on their accumulated data and these he had recently submitted to the engineering department of the company. In the light of the new project this phase of their work had an added importance.
At times, when there was no appreciable breeze (and the boys were always on the lookout for these infrequent occasions) quick flights had been made and the speed of the aeroplane in relation to propeller revolutions had been exactly timed by land marks. Records were also made of the anemometer register on these trips, the latter giving, in the absence of wind, the real pressure on the instrument due to the rush of the aeroplane through the air. At other times, flights were made in the wind, both with and against it. The movement of the atmosphere was carefully measured before these flights and from these figures, compared with the wind gauge readings recorded when the aeroplane was under power—at all speeds of the propeller—tables were made of pressure due wholly to the wind and that caused by the flight of the air craft. Different forms of propellers were used and out of this mass of statistics the engineer of the company and Alan had worked out formulas for speed computation.
“We’ve got to know the wind, Lieutenant,” exclaimed Alan as the boys looked over the engineer’s neatly recorded calculations. “If we don’t know and can’t measure that, we’re as helpless as the old sea dog who navigates ‘by guess and by God.’ We may guess right on its velocity when we start a flight, but in a little while the whizzing sound dulls your sense of speed. You may make a bad mistake in rising or ‘banking’ and you won’t know where you are—especially at sea.”
“‘Bird sense’ is all right for race track stunts,” added Ned, “but it won’t do when you’re out of sight of land. We’ve got to have something that is automatic; something, at least, that we can use as a guide for figures.”
Upon his desk and at other places in the engineer’s room were aneroid barometers, a new pocket device in shape like a watch especially interesting the young aviators. A barograph for automatically recording air pressure and indicating height in the air, not only received attention but was at once repacked in its case to be taken to Newark. A new aerometer was also wrapped up for the same purpose.
“This barograph looks like a good thing,” the engineer explained. “It has a recording cylinder that revolves by clockwork and the indicator needle bears on a series of levers which communicate their displacements to a pen arm. Each movement of the mercury is then recorded on the cylinder. On that you have a graphic story of your up and down journey.”
Compensated and gyroscopic compasses, statoscopes for measuring equilibrium, thermometers and shaft speed indicators were also to be seen. But with the new barograph and the new aerometer, Ned and Alan seemed to content themselves for the time.