How Storks Inspired the Lilienthal Brothers’ Advancements in Aviation

For centuries, the migratory white stork has been a cherished visitor to Europe.

These elegant birds have a habit of building their massive stick nests atop human rooftops and chimneys, foraging in fields, and starring in myths and legends.

They have been associated with good luck and even provide a childhood explanation for the origin of babies.

Beyond their cultural significance, storks have also left an indelible mark on the history of aviation.

The sight of a large stork in flight is nothing short of captivating.

With slow, powerful wing beats these birds have been a source of fascination for generations.

Among those entranced by their flight were two young German brothers, Gustav and Otto Lilienthal, whose curiosity and observations would eventually contribute to the development of human flight.

The Lilienthal Brothers

lilienthal brothers
Credit: Wikipedia

Around 1860, the Lilienthal brothers, hailing from the northern German town of Anklam, ventured to meadows outside their hometown to observe storks in their natural habitat.

To their surprise, they found that they could approach the birds quite closely, even from upwind.

When they approached from upwind, they noticed that a startled stork would make several hops toward them before taking off into the air.

From this behavior, they deduced that it must be significantly easier for the storks to launch themselves into the wind.

Gustav later wrote, “Without some compelling cause, the shy bird would not advance toward us.

Fast forward thirty years and Otto Lilienthal published his seminal work titled “Der Vogelflug als Grundlage der Fliegekunst” (Bird Flight as the Basis of Aviation) in 1891.

While the term “aviation” may seem anachronistic in this context, it’s important to note that “Fliegekunst” refers to the technical skill of flying, not the broader field of human flight.

This work laid the foundation for their subsequent experiments in aviation.

A paperback facsimile of Otto Lilienthal’s 1909 English translation is still available today, offering a fascinating glimpse into the pioneering spirit of these brothers.

Otto Lilienthal is known for inventing the weight-shift hang glider and making around 2,000 flights before the 19th century came to a close.

Tragically, he became a part of aviation history when he died in 1896 after stalling at a height of 50 feet due to a gust of wind.

While the Wright brothers are often celebrated for their meticulous approach to aviation, the Lilienthal brothers‘ research was equally methodical and well-documented.

Grounded in scientific principles, they dissected the puzzle of flight, studying each component in isolation and testing their hypotheses against the known laws of physics.

The Impact of the Stork

Their observations of storks played a pivotal role in their understanding of flight.

By watching storks, they discerned that there was something about the forward motion of the wing, rather than its beating, that sustained the bird with the optimal balance of speed and effort.

They noted the unique wing shapes of storks, with their rounded fronts and tapering rears, as well as the cambered cross sections that aided in flow attachment at the leading edge.

They also identified the phenomenon of a stall and created accurate drawings of streamlines over flat and cambered plates installed and installed conditions.

Using metal rectangles mounted on whirling arms to achieve known wind speeds, the Lilienthal brothers mapped the effects of the angle of attack on lift and drag, producing the first “polar diagrams.”

These diagrams emphasized the critical importance of the preinstall range, where lift increased linearly and far exceeded drag.

All their findings were consistently related back to their observations of birds, recognizing that nature had already provided solutions to the problems they were investigating.

While the Lilienthal brothers’ insights were largely accurate, not all their beliefs about flight were spot on.

They thought that wind, by itself, contributed to lift, leading to the belief that birds flew more readily on windy days.

Additionally, they believed that future aircraft capable of rising from the ground under their power would propel themselves by flapping their wings, a notion that ultimately proved incorrect.

Despite the limitations in their understanding, the Lilienthal brothers began applying their knowledge around 1890 to construct a glider. They wisely did not attempt to replicate a stork’s anatomy, recognizing that a rigid glider presented different challenges.

They designed a lightweight, cambered wing with a fixed vertical stabilizer, a feature absent in birds but essential for a rigid glider.

The pilot’s position, based on their research, was situated at the center of the lift, closer to the leading edge.

Control of roll and pitch was achieved through the pilot’s weight-shifting, mirroring the subtle movements of a bird’s feathers.

lilienthal brothers glider
Credit: Library of Congress

In 1891, a full twelve years before the Wright brothers achieved powered flight, Otto Lilienthal initiated gliding experiments from a hill near the village of Derwitz, just west of Berlin.

To facilitate these experiments, he even had a tall conical mound constructed for launching.

Crowds gathered to witness his flights, and over five years, he completed approximately 2,000 flights, totaling an estimated five hours in the air.

In essence, Otto Lilienthal became the first pilot, and his glider was the earliest incarnation of an airplane.

Summary

In aviation history, the Lilienthal brothers may not be as celebrated as the Wright brothers, but their meticulous observations and experiments with storks laid a crucial foundation for understanding the principles of flight.

Their pioneering spirit and dedication to unraveling the mysteries of aviation remain a testament to the human quest for flight, forever intertwined with the graceful flights of the white stork.

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