Big Debt to Radio

Sun (Auckland), Volume II, Issue 456, 11 September 1928, Page 9

Big Debt to Radio

flyers in Touch With World equipment of plane ■‘Without radio we could not have done it,” was the tribute paid to wireless by FlightLieutenant C. P. T. Ulm when the Southern Cross arrived at Brisbane. The tact that the plane was in wireless communication with the rest of the world during each of the three leaps across the Pacific made aviation history. Radio helped the flyers with their navigation; it drew their path for them. Radio told their friends— and w ho was not their friend during those long hours? —that the three engines were still beating faithfully, that the “gass’ was holding out. Radio sent the hearts of all the world and his wife into their mouths when the message came “Starboard motor is spluttering.” and radio reassured everybody a few minutes later. If the spluttering had continued, and the engine failed, radio would have told ships where to aim for to pick them „p, it they were too far from land to make it on only two engines.

Even if the airplane had been forced down at sea, the petrol dumped, and the engines cut away, messages which would probably Have enabled searching ships to rescue the airmen could have been sent from the floating fuselage. The equipment which did such magnificent work was designed and built in San Francisco, and was a duplicate of that installed in the Dallas Spirit, which was lost in a former attempt to reach Hawaii. The radio apparatus of this machine worked splendidly, and the last thing that was heard of the unfortunate crew was the message: “We are just going into a tail-spin.” Test flights of the Southern Cross, which were made in attempts to break the endurance records, gave plenty of opportunity to test the apparatus, and proved that it could do its job well. A log was kept for just on 100 hours of flying, and it was decided tjat the transmission on a wavelength of. 33.4> metres was relatively free from fading and skip-distance effects, and would be thoroughly reliable for a trans-Paeific flight. THREE SEPARATE SETS There are three separate transmitting sets, and three receivers, the whole apparatus weighing only 1001 b. Most reliance was placed on the short-wave transmitter, which employs one 50-watt tube, with plate and filament supply from a two-unit wind-driven generator. The filament supply is 10 volts, while the other winding supplies 65 volts. This a transformer steps up to 900 volts for the plate. There is a generator on each side of the fuselage, on the under part of the wing, and these were automatically connected or discon-

nected it one of them failed. The small “windmills” to drive the generators were two-bladed, like the propellers of the airplane, and were so designed that no matter what the machine’s speed, the speed of the generator would remain practically constant. This ensured a steady note, easy to follow. The 600-metre transmitter which is intended for communication with ships, was built on the same lines as the short-waver, but it has a much shorter range. Both transmitters, fitted in aluminium cases, are mounted in the wall of the navigator’s part of the airplane, projecting only about eight inches from the wall. the emergency transmitter The third transmitter is an emergency one, designed for use in case the macchine uad to land on the water, so it was made waterproof. It has a one-inch spark coil, and is tuned broadly to 600 metres. The key is under a rubber-covered hole in the waterproof box, so that to send a message the rubber is pressed, thus working the key without letting water into the transmitter. The aerial for the emergency transmitter is 200 feet of stranded wire, which, if it had ever to be used, would be carried up into the air by a balloon. A small hydrogen . container to fill this balloon is carried in the a* 16 " The emergency transmitter, which is battery-operated, will work for eight hours, and on test has been “ e ® r d 200 miles away at night. The aerials for the other transmitters are lengths of wire, weighted ®t the free end, which are carried on reels. Twenty-six feet of wire is “ s ed for the short waves, and 200 feet IO L the longer ones. The receivers are so arranged that sny one of the three tuner and detecor units can be switched across to he two-stage amplifier. So well has radio apparatus—made by Heintz ud Kaufman, Inc.—proved itself, that otrunander Richard Byrd has ordered imilar equipment for his Antarctic expedition.