Sep 012010

He is probably the most versatile and at the same time least known aeronautical pioneer: Enrico Forlanini excelled in not just one but three aeronautical fields. This is the story of the man who built the first engine-powered helicopter, manufactured dirigibles and invented the hydrofoil boat.

Back in July 1877, it must have been a strange sight for the passers-by who were strolling in the small park next to the Scala theatre in Milan. A man of around 30 was feverishly working on a large, flimsy contraption with two sets of sails, which was about two or three metres in diameter. The centre of Milan wasn’t exactly a sailing ground and, besides, the sails were almost horizontal, so what good would that be? The contrivance was also missing any sort of hull, but had gears and steaming cylinders in its centre instead. This gentleman clearly was a madman, and the device could explode anytime and blow everybody into the sky. There was no explosion, but something did indeed lift off into the sky: Hissing and puffing, wildly whirling its sails in opposite directions, the contraption rose from the ground and flew freely for about 20 seconds, ascending to an altitude of 13 metres. The speechless bystanders had just witnessed a flight of the first engine-powered helicopter.

Enrico Forlanini (1848 - 1930)

The man behind all this was Enrico Forlanini and he wasn’t mad. In fact, he knew exactly what he was doing. Born on 13th December, 1848, Forlanini attended a technical school and later entered the military college of Turin to become a sapper officer. His interest in all things technical, and flying in particular, still not satisfied, he asked for a leave of absence to study engineering in Milan. During this time he tinkered around with propellers and helicopters.

These vertical flying machines weren’t something particularly new. The Chinese had used them as toys for centuries and Leonardo da Vinci’s famous sketch is an engineering icon. In the beginning, Forlanini experimented with the newly invented rubber bands as a power source but the Italian wanted something more substantial – a steam engine. As a trained engineer he was well aware of the fundamental technical problems behind vertical flight. He knew that a rotor creates a momentum which has to be counteracted. So he designed his helicopter with a pair of coaxially mounted rotors moving in opposite directions. He also realized from countless experiments that weight was the leading design factor – light weight was paramount. As a result, Forlanini stripped the helicopter’s two-cylinder steam engine of everything that wasn’t absolutely necessary: The heavy control wheel had to go and ultimately, so did the boiler, which was replaced by a simple sphere filled with superheated water. In a design sketch he even got rid of the steam engine itself, planning to eject the steam directly through jet nozzles at the tip of the helicopter’s wings.

While using all his off-duty time to work on these vertical flying machines, Forlanini also realised something else. The military wasn’t exactly the best place to have crazy ideas and build experimental flying machines. To do so, you needed to be free. Consequently, Forlanini left the army for good, started a career as an engineer and business man, and founded his own company. By the turn of the century he finally had the money and the means to start an aeronautical business.

Flying Above the Water

Strangely enough, his early activities were more nautical than aeronautical. But then again, that’s maybe not so strange. Forlanini knew that the principles of flight applied to air as well as water. After all, water is just another medium. To prove it, he started work on a series of seaplanes, or idrottero as he called them, the ancestors of today’s hydrofoils. The idea was to attach to a vessel a series of submerged wings which at the right speed would create enough lift to raise the hull completely out of the water and thereby reduce the water’s resistance dramatically. This was a radically new idea. Winged boats had been built before but they would only rise until they slid or bounced over the water. Forlanini wanted true flight.

In 1898, he started his experiments at the Lake Maggiore. His first prototype was a small dinghy made from two pontoons which was towed behind a motorboat. A ladder of wings, decreasing in size, was mounted at the back and the front of each pontoon. Forlanini knew enough about aerodynamics to conclude that the higher the speed the higher the wing’s lift would be. The faster the boat went the smaller the wings needed to be, which would also conveniently reduce the drag. And indeed, the dinghy, carrying a person, rose out of the water and went flying over the lake. The hydrofoil was born.

While the local fishermen and yachters might have missed this historical moment, they surely wouldn’t have overlooked Forlanini’s next hydrofoil. His ‘Idroplano N. 1’ was a previously unseen and rather intimidating appearance: a silver, cigar-shaped vessel, weighing 1.6 tons and powered by a 70 hp combustion engine. The frightening part was the huge aircraft propellers fitted to the front and the back and connected by a shaft running all the way along the length of the boat. The rather unusual arrangement might be attributed to Forlanini’s ultimate goal. He envisioned his seaplanes to, one day, go fast enough to take flight and become airborne.

In a historic ‘flight’ Forlanini’s hydrofoil boat raises over the waters of Lake Maggiore.

In a historic ‘flight’ Forlanini’s hydrofoil boat raises over the waters of Lake Maggiore.

But the technology wasn’t ready yet. The combustion engine he had used was too  unreliable and so he had to build a second craft with a 25 hp steam engine. But even with this drawback, Forlanini was able to reach speeds of more than 50 kph. In 1911, his ‘Idroplano N. 7’, now without the aircraft propellers and a submerged ship’s propeller instead, reached an incredible, record-breaking 75 kph. Flying smoothly over the waves, the two-ton vessel was capable of carrying two crew members and four passengers.

One of these passengers was Alexander Graham Bell. In his later years the inventor of the telephone became interested in hydrofoils and came to Italy to study Forlanini’s work. Bell would later build his own hydrofoils based on Forlanini’s design. One of these hydrofoils, the HD-4, set a world marine record of 114 kph in 1919, a record which stood for more than ten years.

A whole new type of boat was born, which, to this day, still amazes everybody who sees one of them in action. Forlanini may have invented the hydrofoils and successfully proved their practical use, but his heart lay somewhere else: Dirigibles, those ‘lighter-than-air flying contraptions’ as he used to call them, were his true passion.

Lighter Than Air

The first person to attach a steam engine to an elongated balloon and take off was the French engineer Henri Giffard in 1852. But it took another 50 years before the successful airship flights of the Brazilian Albertos Santos-Dumant started a real craze. Suddenly, every major European nation was working on airships. Back then they were considered engineering crowns – and important military assets.

These airships fell into three different categories: The early airships were non-rigid – nothing more than cigar-shaped balloons powered by propellers attached to the gondola. This type lives on in today’s Blimps, small airships used for advertising or reconnaissance. The most successful category was undoubtedly the rigid design created by Count Zeppelin, whose name became synonymous for airships in general. Zeppelin’s rigid structure allowed it to move the engines and the steering gear away from the gondola, resulting in a much better manoeuvrability. But this came at a price; the support structure was heavy and limited the airships payload.

Enter Forlanini, who had the idea to run a keel from bow to stern. This strengthened beam would carry all the ‘hardware’, i.e. gondola, engine and rudders. The attached envelope, however, maintained its shape simply from the gas pressure. Such a semi-rigid design combined the best of both worlds and would be characteristic for all Italian airships, including the ‘Norge’ and ‘Italia’, which Umberto Nobile used for his polar expeditions in the late 1920s.

Forlanini had been working on his design for eight years when, on the 22nd July, 1909, the F1 finally started on her maiden voyage. The proudly named ‘Leonardo da Vinci’ may not have been the first Italian airship, two others had been airborne before, but it was certainly the most innovative. In addition to the keel beam, the integration of the passenger car into the gas balloon for improved aerodynamics was another first. The ‘Leonardo da Vinci’ was 40 metres long, had a volume of 3,700 cubic metres and was powered by a 40 hp Antoinette combustion engine, which drove a huge three-bladed propeller at the stern. Its maiden voyage was short and ended with an express landing, but after replacing the single propeller with two side propellers at the rear third of the keel, the ‘Leonardo da Vinci’ completed a number of successful flights and became a much admired sight in the skies over Milan.

In fact, the F1 became so popular that Forlanini was able to build a second airship funded by the city of Milan through a public subscription. Aptly named ‘Città di Milano’, the F2 had four times the volume of the F1 and was powered by a 170 hp engine. Unfortunately, after only a year in military service, the ‘Città di Milano’ was destroyed in 1914 by a fire when the hydrogen ignited after an emergency landing.

A Passion for Airships

In spite of the disaster, Forlanini had, by then, made himself a name as an airship designer. Finally in the business he always wanted to be in, he built his own factory in 1914. The buildings and the hangars of the ‘Societa Leonardo da Vinci’ were specifically designed for the manufacture of airships. Located next to a military airfield, they were also conveniently close to Forlanini’s main customer. In the coming years, the ‘Societa Leonardo da Vinci’ would build four more airships for the army.

Forlanini used a keel to strengthen his airships. A design which influenced all future Italian airships.

Forlanini used a keel to strengthen his airships. A design which influenced all future Italian airships.

Although initially praised as super weapons, it soon became clear that airships were too vulnerable and no match for the increasingly powerful airplanes. The Golden Age of the airships was coming to an end. Forlanini still believed in them, however, and tried to establish passenger services between major Italian cities after the war, but the business never really ‘took off’.

In the end, Forlanini was forced to move on to other business fields, but he never gave up on his beloved airships. Right until his death on the 9th October, 1930, he worked on his greatest creation, the ‘Omnia Dir’. One last time Forlanini was literally ‘pushing the envelope’ of airship design. The ‘Omnia Dir’ was the first and only airship in the world controlled by air jets. Two centrifugal fans were mounted on the nose and the stern of the dirigible. Via a cross configuration of valves, a jet of air could be directed up, down, sideways, in or against the flight direction. This provided the ‘Omnia Dir’ with an unprecedented manoeuvrability, effectively reducing the ground crew for handling the airship from hundreds to only a few men. For the same reason, movable thrusters were reintroduced in the design of the modern Zeppelin NT.

Forlanini’s ingenious valve configuration also bears a striking resemblance to the manoeuvring thrusters of a spaceship. While the name Enrico Forlanini might be almost forgotten, the genius of the man who was at home in so many skies is now carrying us to the ‘final frontier’.

Matthias Meier
Englische Dokumentation über Forlanini mit z. T. Originalzitaten zu seinen Hubschraubern, Luftschiffen und Tragflächenbooten.
Die alten Werkstätten Forlaninis wurden in den 90er Jahren restauriert. Das Officine Leonardo da Vinci beherbergt heute eine Forlanini-Dauerausstellung und wird als Kultur- und Ausstellungszentrum genutzt. (it.)
Ausführlicher Artikel über das Leben und Werk von Enrico Forlanini in Italienisch.
Eine kurze Geschichte der frühen Helikopter.
Sehr ausführliche Seite zum Thema Tragflächenboote. – 0313.html?tracked=1
Zwei historische Artikel über Forlaninis Luftschiffe.

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