Oranges and aeroplanes give life to Yuma

Press, Volume CXIII, Issue 33153, 17 February 1973, Page 11

Oranges and aeroplanes give life to Yuma

("By

A. J. PETRE)

Yuma, Arizona, is a desert-girdled town of 25,000, just over the Californian border. One of its major industries is citrus fruit, another is the 10,000 ft - long Yuma airfield, shared by the United States Marine Corps and the McDonnell Douglas Corporation. When a party of New Zealand journalists visited Yuma recently at the invitation of McDonnell Douglas, it was to see Air New Zealand's new DCIO wide-bodied jetliner engaged in crewtraining.

The crew, led by Air New Zealand senior pilot. Captain P. Le Couteur, had already spent months in "classroom” training, and training on simulators. Now they were each getting about eight hours of actual air time, carrying out in reality the manoeuvres and procedures they had already practiced hundreds of times in ground training. And while the Air New Zealand DCIO and a Turkish airlines 10 made occasional "touch and go” approaches. Marine Corps jets—fighters and light bombers—roared in and out one after the other. This provided an unexpected but convincing demonstration of one of the features of the DC10: its quietness on take-off and landing. The sound of the big tri-jet was often completely drowned by the noise of a fighter taking off on another strip several hundred yards away. Yuma has several attractions as a base for both military and civilian aircraft testing and training. The desert air is remarkably clear —incredibly so after a few 7 days in the polluted air of Los Angeles. Clear sky for flying The strip is the longest Marine Corps airfield in the United States, it gives the Corps air controllers good experience of comparatively heavy air traffic, and it is close to the clear and uncongested skies of Baja California and Mexico. It is over these areas much of the light testing of McDonnell Douglas aircraft is done. The area also has a delightful climate—in winter.When the New Zealanders stood on the airfield on a typical winter’s day, the temperature was a pleasant 21 degrees Celsius (70 degrees F) or so.

In summer, temperatures two-thirds as high again are far from unknown. On several occasions last summer, flying from the field had to be halted for fear of bursting the jets’ tyres: the runway surface temperature exceeded 150 degrees Fahrenheit.

Yuma, indeed, is not very manv miles from a small township called — appropriately — Thermo. This understandably small settlement can often boast the hottest summer temperature in the United States: nearly 14# degrees Fahrenheit has been recorded, and that is the same as some of the highest temperatures experienced in the notorious Death Valiev.

But in winter, Yuma is pleasantly warm, and Hollywood film crews are often found among the rolling desert dunes near the town, filming epics which purport to be based in the Sahara. Not all the desert is as bleak. In spring, there is a vast and colourful selection of desert flowers and sagebrush — including the tumbleweed immortalised in so many Western films. And the rattlesnakes, although common, are generally more frightened of vou than you are of them, the tative’s are quick to assure visitors. The prominence given to snake-site kits on the shelves of local drugstores does, however, make one wonder. One of Yuma's main winter attractions, apart from the inevitable “driveins” and the several channels of colokr television (including one from Mexico), are the races. Most of the New Zealand party spent an evening there, and left financially

somewhat the worse for their experience.

They also encountered language difficulties: a waitress at the track bar finally confessed her difficulty with the orders: “Say, youse guys speak English so darned good I cain’t hardly understand ya.” A rare compliment for a New Zealander—or perhaps a remarkably tactful way of describing the problem. The McDonnell Douglas test facility at Yuma played a major part in the development of the DCIO, as indeed it has in the development and testing of most aircraft bearing the DC prefix. There are only limited servicing facilities, for the strip is but one hour by air from the company’s plant at Long Beach, California, about 300 road miles away. But there is a permanent staff of about 18 in the McDonnell Douglas buildings, including top-level test engineers.

And should problems arise, they can be discussed “face to face” with the other experts at Long Beach: closed-circuit colour television and a multi-channel telephone line connects the meeting rooms at Yuma and Long Beach.

The engineers said they found it a great advantage to be able to hold a joint conference by television—and there is also a television camera on the Yuma tower to give the Long Beach experts a look at the aircraft itself, if needed. Tae men in the s9m DCIO project building at Long Beach—a building crammed with nearly s2om worth of computers — have even greater communications facilities at their command. At the touch of buttons they can talk to the aircraft on test, the Yuma base, and at the same time automatically monitor by telemetry up to 400 separate functions on the test aircraft itself, which may be flying thousands of feet above Mexico at the time. The DCIO, in fact, is said to be the most thoroughly tested aircraft ever built.

Computers figured heavily in the aircraft’s design, and also in its testing: the aircraft was “test flown” on the computers long before the first real flight took place.

The aircraft has 187 separate identifiable control and flight systems, most of which work in integration with

other systems. By the time the aircraft entered service, it had flown 1550 hours of air testing, plus twice this time of computer testing. In the 1500 hours of flight testing, the engineers—with the help of the computers and telemetry — identified more than 3000 items they wanted to investigate further and improve. More than 2500 hours was spent testing models in 12 different wind tunnels; the positioning of the “tail” engine presenting particular problems.

All of this cost a great deal, but the whole DCIO programme is, according to McDonnell Douglas, a $lOOO million programme. Accordingly it is no exaggeration to say that the future of the company was at stake in the DCIO.

But computer testing — which, along with some flight testing, will continue as long as DCIO aircraft are in service — saves money compared with the estimated $20,000 an hour cost of flight testing. Vast hangar One of the most interesting aspects of the DCIO testing is at Long Beach, jn a hangar so vast it makes the DC 10 look almost a toy. The hangar, in fact, was designed with a possible future aircraft, code-named the C 6, in mind. The sixengined C 6, scheduled for the 1980 s, will itself dwarf the DCIO and other big jets of today. In the hangar, a complete DCIO, in sections, is even now undergoing fatigue tests. Rams and levers, controlled and monitored by equipment said to be more sophisticated than that used in Apollo moon missions, flex and test every part of the aircraft’s structure. There are 138 load actuators attached to the aircraft, and more than 1200 strain gauges check the results. 40-year tests The end result of ail this testing — which the engineers emphasise would have been impossible with computer techniques derived from the company’s involvement in space technology — is that the aircraft is sold as a 60,000-hour aircraft — but it has been tested satisfactorily to 120,000 hours. In layman’s terms, 60,000 hours is the equivalent of about 20 years of intensive airline service. But the DC 10 has been tested to the equivalent of 40 years of service. Some of the famous DC3 aircraft have now flown about 100,000 hours, and have, in the latter stages of their lives, developed definite patterns of fatigue.

This, the McDonnell Douglas say, has given the company years of experience in the field of structural fatigue. So, in a way, the monster DCIO owes something to the DC3 which is barely bigger than the 10s rear engine-housing. Surrounded by computers in the air-conditioned and dimly-lit interior of the DCIO project building, it is easy to be overwhelmed by the surrounding computer screens and the atmosphere of higher mathematics and complex technology. But the men at Long Beach, the test-crews in the aircraft over Yuma or Mexico, and the staff at the “flight development facility,” as it is known, at Yuma, work as a close-knit team. It is a team which remains close-knit in spite of distance, thanks to modern communications. And it is a team which bears the responsibility for the DCIO being the most thoroughlytested airliner ever to take to the air.

But one warning about Yuma —never pick the oranges that hang so invitingly in the unfenced groves bordering the roads. Picking up even a windfall carries an automatic fine of ssoo—or six months gaol. Fences are not required.