The Airplane - Jay Spenser [106]
Henson used just three carriage wheels in a wheelbarrow configuration to keep weight low. In this regard at least he was far ahead of his time, for he had just given aviation the tricycle landing gear.
Nearly all airplanes built today feature the tricycle landing gear. This configuration places the main wheels behind the airplane’s center of gravity and has a smaller wheel or wheels at front. Aside from a few crop dusters, homebuilts, and sport airplanes, this configuration is all but universal.
That was not always the case. Aviation initially standardized with the main wheels forward of the center of gravity and a skid at rear (later replaced by a tailwheel). Known as the conventional landing gear, that configuration predominated before World War II. There were exceptions then as now, of course, but in general “taildraggers” ruled before World War II and “tri gears” after the war. As for World War II itself, one finds examples of both, although the former predominated.
The conventional landing gear has a drawback. Since the weight is behind the main wheels, the airplane must be perfectly lined up fore and aft with the runway and the pilot must have killed any lateral drift before touching down. If not, the center of mass will try to swing around in front of the wheels, causing the airplane to veer off the runway in a humiliating and potentially damaging horizontal circle known as the ground loop.
Early pilots didn’t worry too much about ground looping because airports back then were open fields. Consequently, takeoffs and landings could always be made directly into the wind, keeping things simple. Only later, as the world moved to defined runways, did pilots have to hone their crosswind landing techniques.
There is genuine satisfaction to flying taildraggers. It demands skills and offers joys not found elsewhere in aviation. Landings in gusting or quartering crosswinds are particularly challenging, requiring pilots to be alert and quick on the controls, the rudder pedals in particular. Since side gusts on the vertical tail turn the airplane like a weathervane, it is often said that tailwheel landings are not over until the airplane is parked and tied down.
In contrast, if tricycle-gear airplanes are landed not properly lined up, the center of gravity is forward of the main gear, so momentum wrenches the wheels around to make the airplane track straight ahead. Another benefit of tricycle gears is that the airplane sits level when on the ground instead of nose high. Not since the days of the DC-3 have boarding airline passengers had to hike uphill to claim their seats.
Otto Lilienthal needed no wheels. Like all hang-glider pilots, he took off and landed on his own two feet. Stout brogans were his landing gear of choice.
In the air, Germany’s birdman resembled a bird of prey. The reason is his dangling legs, which he threw around to shift his direction of flight. Because birds tuck their legs back in flight for reduced drag, those flailing legs evoked extended talons rather than normal flight.
It was a different story when the Wright brothers built and flew their first two gliders at Kitty Hawk. Not needing to shift their weight for control in the air, they tucked their legs up in flight like a bird. In turn, European experimenters put the Wrights to shame by adopting wheeled undercarriages from the outset. The Wrights stuck with skids far too long, perhaps because they viewed their airplanes as scientific proof-of-concept vehicles first and practical machines second.
In 1609, English explorer Henry Hudson sailed up a North American river that would bear his name. Three centuries later, New York City—located at the mouth of the Hudson River—staged a transportation-themed