Ask the pilot

How JetBlue will save Eero Saarinen's wonderful JFK legacy. And just how does a jet engine work?

By Patrick Smith

Published December 5, 2003 8:30PM (EST)

Not sure how many of you accepted my challenge to savor, rather than dread, the experience of flight during your Thanksgiving travels. Those whose journey included a visit to John F. Kennedy International Airport in New York may or may not have noticed the faded beauty of Eero Saarinen's dormant TWA terminal, this author's favorite airport edifice and a must-see on anybody's tour of commercial air-flight landmarks. When I last wrote about the famous structure last year, TWA had vanished and the space was vacant, its fate being argued between preservationists and Port Authority bureaucrats. As these things tend to go, few were optimistic, and the demolition men were readying their wrecking balls, but this time there's good news.

The 1962 building, the first major terminal in the world built expressly for use by jet airliners, is a modernist masterpiece and, until the dissolution of TWA, the perfect backdrop for revisiting a little jet age enchantment. Saarinen, a Finn whose other projects included the Gateway Arch in St. Louis and the sweepingly beautiful main terminal at Washington Dulles, described his TWA as "all one thing." The lobby is a fluid, unified sculpture of a space, wildly futuristic yet firmly organic. It's a kind of Gaudí inversion, a carved-out atrium reminiscent of the caves of Turkish Cappadocia, overhung by a pair of cantilevered ceilings that rise from a central spine like huge wings. As did the spidery "Theme Building" at LAX, conceived at the same time, it became an eccentric icon. Not necessarily because of any thumbprint novelty, but because it returned a sense of identity to the modern airport, a vitality that would lend itself in the years to come to a host of facilities around the globe.

In the mid-1990s I worked in that building, based there with the commuter affiliate of TWA. Sometimes I'd sit in the second-story restaurant looking down into the lobby, at the gangs of kids in sandals who knew nothing of the place, eyes locked on their copies of Details or Spin and waiting for the final call to Fort Lauderdale or Rome or Tel Aviv. Dishonored by then as "Terminal 4," it was undersized and forlorn, plaintive and world-weary in that way only airports can be -- greased and smeared by every nation and culture without ever having lifted its girders from the Jamaica Bay fill. Clutches of sparrows and starlings lived in the yellowed rafters and would swoop around grabbing up crumbs.

Surprisingly, and thanks to efforts of the city's Municipal Arts Society, a tentative agreement has been reached that will leave the terminal not only standing but also rejuvenated as the showpiece property for Kennedy's newest and hippest hometown airline, JetBlue Airways.

According to the plan, which awaits FAA approval, JetBlue will use the building as an entrance hall and ticketing plaza. Flights will arrive and depart at an all-new secondary building to be built behind it, but Saarinen's main space will be left intact as a central lobby, replete with the usual retail shops and restaurants. Boasts a November issue of the Manhattan User's Guide, "Eero Saarinen's TWA terminal at JFK will remain one of New York's treasured architectural landmarks."

I've seen no blueprints or mockups, but considering JetBlue's standards of style and efficiency, I imagine the results will be outstanding. Fitting, perhaps, that JetBlue should be the new tenant: The ultrasleek carrier represents the newest twist to the air travel model. What more pleasantly ironic context for its experiment than Saarinen's paragon of jet age vision?

(Sigh. My electronically submitted pilot application, along with about 7,000 others, sits in a huge virtual stack on a JetBlue mainframe somewhere.)

Elsewhere at Kennedy, preservationists have also been busy over at Terminal 8, aka the American Airlines terminal. When completed in 1959, the tricolor stained-glass window along its façade was deemed the world's largest by the record keepers at Guinness and has remained so ever since. As part of a billion-dollar, seven-year project, American's JFK facilities are being totally rebuilt, and authorities say the window will be kept.

And don't forget, just across Queens at La Guardia you can savor the famous Marine Air Terminal (1939), formerly the property of Pan Am and now directly adjacent to the Delta Shuttle. From the sidewalk, facing the blue Delta Shuttle awning, look just to the left and you'll see Marine Air's beautiful art deco entryway. (As I was taking a photograph of those polished silver doors one day, a Port Authority cop asked me what the hell I was doing and chased me away.) Notice also the flying fish, set in relief around the rooftop.

If you're inside, face the Delta Shuttle ticket counter and look left; you'll see a short passageway. Ten or 15 steps carry you through a doorway and into aviation history. Inside the rotunda is a 360-degree mural and cutaway of an old Pan Am seaplane.

The mural, "Flight," is a 1952 work by artist James Brooks. As it traces the history of aviation from mythical to (then) modern, Icarus to flying boat, you may notice the painting's style is a less-than-shy nod to socialist realism. At the height of '50s McCarthyism, in a controversy not unlike that surrounding Diego Rivera's infamous mural at Rockefeller Center, it was declared a gesture of socialist propaganda and covered over with gray paint! Not until 1977 was it restored.

I'm always lobbying for flyers to check this building out, but rarely do passengers wander through. Thus, if nothing else, its usually unoccupied wooden benches make for an almost churchlike respite from the Shuttle's crowds.

You once wrote that your job as an air travel columnist isn't to burden readers with technical jargon or bore them with specifications about airplanes. "To travelers," you said, "a discussion of GPS satellites or how a jet engine works is guaranteed to be uninteresting." Well, if you don't mind my asking, how does a jet engine work?

In retrospect, I suppose there's nothing terribly tiresome about this question, and perhaps I owe it to readers to address such a core topic.

Essentially, air is blown out the back faster than it's drawn in the front, pushing the plane forward. The most powerful motors made by Rolls-Royce, General Electric and Pratt & Whitney generate in excess of 100,000 pounds of thrust.

Picture the engine's anatomy as an assembly of geared, rotating disks -- compressors and turbines -- like a series of back-to-back fans. Air is pulled in and directed through the compressors. It's squeezed tight, mixed with vaporized kerosene, and ignited. The combusted gases then come roaring out the back. Before they're expelled, however, a series of rotating turbines absorbs some of the energy. The turbines spin the compressors and the large fan at the front of the nacelle. Older engines derived almost all of their thrust directly from the hot exploding gases. On modern ones that big forward fan does much of the work, and you can think of a jet as a kind of ducted fan, spun by a core of turbines and compressors.

Besides providing thrust, the engines are tapped to supply the electrical, hydraulic, pressurization and de-icing systems. Hence the term "power plant."

A turboprop engine is, at heart, a jet. In this case for better efficiency at lower altitudes and along shorter distances, the compressors and turbines drive a propeller rather than generate thrust directly. Loosely put, a turboprop is a jet-powered propeller. Hence the name jet-prop, sometimes used in lieu. There are no pistons in a turboprop engine, and the prefix shouldn't elicit confusion with turbocharging in the style of an automobile. Turboprops are safer and more reliable than pistons and offer a more advantageous power-to-weight ratio. They're also expensive, which is why most private planes don't have them.

How do the engines start? On TV and movies you hear the whine or see the prop begin to turn slowly, etc....

At least a few of you are picturing keys, I know.

The compressors get spinning either via electric power (most turboprops) or compressed air (most pure jets). Once a certain rpm is established, fuel and ignition are introduced and the engine is accelerated to idle speed. The movement of levers, switches and buttons required to pull this off varies from plane to plane, and the command to start is preceded by a couple of lengthy checklists. From there, the power levers -- or "throttles" if you'd rather -- are adjusted to deliver thrust as needed.

With turboprops, electricity from an outside source -- usually an external ground power unit (GPU) -- gives the juice. A GPU, towed behind a small tractor, looks like one of those generators used at roadside construction sights. The plane's batteries aren't used for routine starts because the power draw is very strong.

With jets, the auxiliary power unit (APU), a small motor typically found at the very rear fuselage, provides the compressed air. (Smaller jet engines can be started via electric power, but you don't find these on most airliners.) The APU, you might recall from a previous column, also provides cooling and electricity while a plane is at the gate with engines shut down.

The first commercial airliner with an APU as standard equipment was the Boeing 727, which debuted in 1964 with Eastern Air Lines. Until then, high-pressure air was plumbed in for starts via an external supply. The old DC-8 freighter I flew needed one of these so-called air carts at every departure.

Due to aerodynamic resistance during flight, an engine's innards, be it turboprop or pure jet, may continue to spin even if combustion ceases. Thus a failed engine, depending on the nature of the mishap, can sometimes be restarted aloft from this "natural" rotation free of assistance from the APU, batteries, etc. It's all about rotation.

If the APU supplies ground power, why do you often see the engines turning while a plane rests at the terminal? Isn't that a waste of fuel?

Jets almost never run their engines at the gate. What you see is the wind spinning the first stage turbofan. Despite its weight and size, the breeze can rotate that fan like a windmill, sometimes quite rapidly. If that seems impossible when a plane is cornered against a building or facing in the wrong direction, that's because the wind is coming from behind. On a modern jet engine, some 80 percent of intake air is blown around the core of compressors and turbines, providing a clear shot at the fan blades from the rear. The wind blows through this duct between core and cowl and sets the assembly in motion.

Next week: Did I just see Air Force One?

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Patrick Smith

Patrick Smith is an airline pilot.

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