SP Guide Publications puts forth a well compiled articulation of issues, pursuits and accomplishments of the Indian Army, over the years

— General Manoj Pande, Indian Army Chief

I am confident that SP Guide Publications would continue to inform, inspire and influence.

— Admiral R. Hari Kumar, Indian Navy Chief

My compliments to SP Guide Publications for informative and credible reportage on contemporary aerospace issues over the past six decades.

— Air Chief Marshal V.R. Chaudhari, Indian Air Force Chief

Commercial Aviation - Leaving on a Jet Plane

Issue: 05-2009By Group Captain (Retd) Joseph Noronha, Goa

Mid-1970s, attracted by the speed and comfort of the new jetliners, passengers responded enthusiastically and numbers soared

During the first half-century of aviation, the air buzzed with the whirr of propellers powered by piston engines. Early passenger aircraft were hard put to compete with the speed of the railroad. Gradually, airliners became much faster than trains. However, manufacturers always came up against the inherent limitation of propellers—their tips could not safely rotate faster than the speed of sound. This limited the thrust they could produce. Consequently, the airliners of yore were puny and painfully slow in comparison with today’s powerpacked behemoths. A strong impetus was needed and it was provided by the invention of the turbojet engine.

The Inventive British
Jet propulsion, based on Isaac Newton’s Third Law of Motion, remained just a theory until Frank Whittle, a British pilot, designed the first turbojet engine in 1930. Whittle’s engine was untested for several years. The Germans were the first to actually produce a jet aircraft. Based on a design by Hans von Ohain, the Heinkel He 178 first flew on August 27, 1939. The outbreak of World War II, however, ensured that this revolutionary technology remained confined to the military domain for a decade or more.

Early jet engines were excruciatingly noisy. They guzzled fuel, which drove up costs and limited range. They also had much higher operating temperatures that required very expensive metal alloy components. It was predicted that while jetliners might be fast they would probably not be commercially viable. As a result, US airlines were somewhat reluctant to embrace this risky, unproven technology. The British had no such inhibitions. On July 29, 1950, a British European Airways (BEA) Vickers Viscount operated the world’s first turboprop scheduled service from London to Paris. Meanwhile, de Havilland built the world’s first commercial jetliner, the Comet 1—a milestone of British aeronautical design. On May 2, 1952, the British Overseas Aircraft Corporation (BOAC) flew a Comet from London to Johannesburg—marking the world’s first commercial jet service. Jetliners were undoubtedly faster than other planes, but how much faster? While the most famous propeller airliner of the time, the Dakota DC-3, had a cruising speed of approximately 290 km/hour, the turboprop Vickers Viscount cruised at around 440 km/hour. The Comet increased this to 770 km/hour. It could also climb faster and fly higher. Airlines and passengers were greatly relieved to be able to soar above the turbulence and storms of lower altitudes, transforming an airliner from a skittish, stomach-churning contraption into a stable and elegant lounge in the sky. However, like the celestial object after which it was rather unfortunately named, the Comet 1 faded into oblivion a couple of years after its introduction following two back-to-back fatal accidents. The airliners’ fuselage burst during flight—the result of metal fatigue caused by repeated pressurisation cycles.

America Races Ahead
In the meantime, thanks to Juan Trippe, Pan American’s legendary CEO, the American airline industry was persuaded to embrace jet engines. Boeing’s 367-80 of 1954 introduced the now ubiquitous configuration of the jetliner—podded engines and low, swept wings. Though other types would appear, such as aft-mounted engines and T-tails, the basic configuration of the jetliner was set by this remarkable design. It also ensured that the US commercial aircraft industry would dominate the global marketplace for another quarter-century, until challenged by the rise of Airbus. On October 26, 1958, Pan Am flew its first transatlantic jet flight from New York to Paris, a Boeing 707-120. It had 111 passengers—the largest number to board a single, regularly scheduled flight till then. Within a year, the 707-320 was adopted by a dozen airlines. Not all airlines pinned their hopes on the Boeing 707, though. Douglas had unmatched experience in building the best piston engine airliners in the world and, from September 1959 onwards, many airlines chose the jet-powered Douglas DC-8. The Soviet national airline Aeroflot held the distinction of operating the world’s first regularly scheduled and sustained passenger jet service with its Tupolev Tu-104 aircraft from Moscow to Irkutsk (in the Soviet far east) in September 1956. Air France introduced the graceful Caravelle, built by Sud-Aviation, in 1959.

In 1960, excluding US-owned airlines, the top airlines of the world were Aeroflot, Air France and BOAC. Most European airlines were state-owned. The German airline Lufthansa was among the fastest growing airlines in Europe and rapidly expanded its services and fleet through the late 1950s and 1960s. Like most of the major airlines of the world, including Air India, it entered the jet era in 1960 with the Boeing 707. 1960 was also the year when USA was connected to India by an Indian airliner.

All misapprehensions about the commercial viability of jetliners were soon resolved. Jet engines were simpler and more reliable than piston engines, since they had far less moving parts. They burned refined kerosene, which cost half as much as the high octane gasoline used by piston engines. They produced less vibration, putting less stress on the airframe. They had lower maintenance costs. Seeing the writing on the wall, airlines worldwide switched to the new jets with amazing rapidity. The piston engine airliners of the 1950s were quickly made obsolete by the Boeing 707 and DC-8 and, during the 1960s; short-haul jets practically eliminated large turboprops such as the Vickers Vanguard and Lockheed Electra. The efficiency savings offered by turboprop airliners was ignored—speed was the order of the day.

Taking a cue from the design of the Caravelle, Boeing built the 727, a larger and faster jetliner with three engines, and perfect for both medium and short-distances. By 1970, the 727, one of the most versatile aircraft of the jet era, became the fastest-selling commercial jet airliner in the world. It was the first to pass the 1,000 sales mark and, by the mid-1970s, as many as 60 airlines worldwide were flying it. It was eventually surpassed by the Boeing 737.

Attracted by the speed and comfort of the new jetliners, passengers responded enthusiastically and numbers soared. Juan Trippe expected that this trend would continue, as did William Allen, president of Boeing. Both men were visionaries and dreamt of a huge, new airliner which eventually took shape as the Boeing 747. On January 22, 1970, the first Boeing 747 took off from New York bound for London. The 747, dubbed jumbo jet, doubled the capacity offered by existing airliners to over 450 passengers. It was the world’s first wide-body jetliner, and remains the best selling. The fascination with wide-body jets produced two other notable examples—the Lockheed L-1011 TriStar (August 1971) and the Douglas DC-10 (April 1972)—each capable of carrying about 300 passengers.