Stranger to the Ground

Now, behind my left shoulder, a low whine begins. Intrigued by the new tone that my harlequin airplane has discovered, I listen attentively. The whine rises higher and higher, as if a tiny turbine was accelerating to tremendous speed. My left glove inches the throttle back an inch and the whine calms a fraction; throttle forward and it regains its spinning song. In another airplane the whine would be cause for serious and concerned interest; in my airplane it is cause for a slight smile under the green rubber oxygen mask. I had once thought that I had heard all the noises that it was possible for this airplane to make. After a moment, the whine dies away by itself.

Thud. There is the smallest tremor in the throttle, and a sound as if a hard snowball had hit the side of the fuselage. In an F-100 or an F-104, in the new airplanes, the thud would bring a sudden stiffening of pilot and a quick re-check of the engine instruments. In another airplane the thud would likely mean that the engine has thrown a turbine blade, and that a host of unpleasant consequences are to follow. In my ’84 though, a thud is just one more sound in the kaleidoscope of sounds that the airplane offers to its pilot, another evidence of an unconforming personality hidden in the metal.

My airplane has a great variety of individual quirks; so many that before we arrived in France it was necessary to arrange a little meeting with the control tower operators, to tell them about the airplane. The boom of the engine start could send the uninitiated scrambling for the fire alarm. When the engine is idling on the ground, turning a modest 46 percent of her available rpm, she hums. She hums not quietly to herself, but an amplified, penetrating, resonant distracting “MMMM” that makes the crew chiefs point painfully to their ears, reminding pilots to advance the power, to increase the rpm past the point of resonance. It is a very precise and human hum she makes, and there is no doubt over all the airbase that an F-84F is preparing to fly. Heard from a comfortable distance, the airplane is setting the note for the song of her higher thunder. Later, in the sky, there is usually no trace of her resonance, though the cockpit is filled with the other sounds of her engine.

Every once in a while, though, I fly an airplane that hums in the air, and the cockpit is a finely engineered box of torture. Back on the throttle after takeoff, to cruise cross-country, to stay on a leader’s wing. MMM . . . Back a little more on the throttle. MMM . . . The resonance ripples through me as if I were a metal servomotor bolted to the fuselage. I shake my head quickly. It is like trying to disperse a horde of hungry mosquitoes with a toss of the head. I open my eyes wide, close them, shake my head again. Futilely. Soon it is difficult to think of flying formation, of cruising, of navigation, of anything but the all-pervading hum that makes the airplane tremble as with a strange malady. Speed brakes out, halfway. Throttle open to 98 percent rpm. The hum subsides with the increased power, replaced by the tremble of air blasting against the speed brakes. To fly two hours in a badly humming airplane would reduce its pilot to a hollow-eyed automaton. I would not have believed that such a simple thing as sound and vibration could erode a man so quickly. When I wrote one airplane up for severe engine resonance, I discovered that it was most often caused by a loose tailpipe connection, allowing the eight-foot tube of stainless steel to rest lightly against the airframe like a tuning fork against a water glass. The perfect tool of a saboteur in wartime would be a wrench with which to loosen, ever so slightly, the tailpipe mounting bolts on enemy airplanes.

Other things. The airplane has a hundred little jokes to play. A hundred little things that seem to indicate that Something Is Wrong, when nothing at all is amiss. Just before takeoff, during the engine runup on the runway, grey smoke floods into the cockpit, geysering from the air vents. Engine fire? A broken oil line in the engine compartment? No. The cockpit air temperature control is set too cold, and the moist outside air is turned to instant fog by the obedient cooling system. Press the temperature control to hot for a moment, and the smoke disappears. And the airplane chuckles to herself.

The same moment, runup. Smoke, real oil smoke, streams from the fuselage, blasting down from a hidden orifice onto the runway, splashing up to wreathe the airplane in grey. Normal. Just the normal oil-mist from the pressure-lubricated bearings, venting overboard as designed.