The Airplane - Jay Spenser [38]
A decade after the Wright brothers’ success at Kitty Hawk, the four-engine Sikorsky Ilya Muromets took wing in Russia.
National Air and Space Museum, Smithsonian Institution
Climbing out after the refueling stop at Orša, Sikorsky corrected for constant thermals that jounced his machine like a bad road. Updrafts filled the cabin with the sweetness of sun-warmed meadows and the heady redolence of flowering hedgerows. Trees gave way to grazing cattle and astonished field hands as Sikorsky followed the land’s contours. Squinting into the sun, he let the Dnieper River lead him south to a hero’s welcome at Kiev, his hometown.
The reverse course was flown the following day. That evening, having surmounted mechanical troubles and bad weather, the crew of the Ilya Muromets was home again in the city of Peter the Great. They had covered 1,400 miles (2,200 kilometers) in four stages, putting the rest of the aviation world to shame.
Here in imperial Russia’s capital in 1914 was what George Cayley had imagined and William Henson had tried to build: a practical airliner offering genuine utility. It would have written a different beginning to commercial air travel had world events not intervened.
A week after Sikorsky’s flight, a hotheaded young Serbian nationalist assassinated Austria’s Archduke Franz Ferdinand, presumptive heir to the Austro-Hungarian throne, and his wife, Sophie, in the streets of Sarajevo. That act of violence triggered a series of military escalations across the European continent that by August erupted into open warfare. World War I had begun.
Instead of building airliners, the Russo-Baltic Carriage Factory would roll out more than seventy Sikorsky Ilya Muromets bombers. They found limited use because the Great War needed smaller, short-range tactical bombers to support military operations right at the front, not big strategic ones capable of flying far beyond enemy lines.
Preoccupied with the longer and more active Western Front, the Allied powers paid scant attention to the war in the east. Not so the Germans who met Sikorsky’s amazing giants in the air or shuddered under their bombs on the ground. The German Riesenflugzeug (giant airplane) program of World War I was the direct response to those lumbering marvels.
How did Igor Sikorsky come up with the amazing Ilya Muromets? The answer lies in part in this airplane’s extremely long wings. Sikorsky knew that slender wings of great span lift more efficiently than broader, shorter wings of the same total area.
In fact, there were many secrets just waiting in the wings.
Birds have thin wings, so that was where flight’s pioneers began. But how did one go about constructing a scaled-up bird wing that could support a flying machine? It was a huge challenge, one exacerbated by scale effects and the constant need to keep weight to a minimum.
The construction of ships, buildings, and bridges provided adaptable engineering knowledge along with skills, tools, and techniques in woodworking, metal fabrication, and other disciplines. In the patent drawings for his 1843 Aerial Steam Carriage, trained mechanical engineer William Henson called on all of them as he focused his creative energies skyward.
The wings that Henson designed for the Aerial Steam Carriage comprised three beams extending from each side of the fuselage. These lateral spars were the wings’ primary load-bearing members. He crossed them with fore-and-aft members called ribs that created a structural lattice and gave the wings their cambered airfoil shape.
Thus bound and internally reinforced with cross-bracings, these spars and ribs together formed lightweight wing panels. Henson’s drawings called for them to be encased in cloth treated to prevent air from penetrating its weave. Henson specified oiled silk or, if that was too expensive, canvas.
Wing panels constructed this way are light and hold together well, but in one key regard they are woefully deficient: they cannot resist twisting