The 10 Strangest French Aircraft

SNCAC NC.3021 Belphégor high-altitude research aircraft

France is a nation of contradictions, simultaneously ultra-conservative yet radically inventive to the point of absurdity, the forces of conformity and eccentricity have long been at odds in this great European nation. There is a reason that the words outré and avant-garde came from France, such is the presence of radical new thinking in the culture. France’s adventures in aviation embrace both these seemingly opposed aspects of the national psyche, but it is in the realm of the outlandish that we will dwell tonight, mon ami.

Simply developing excellent flying machines wasn’t enough for the French aeronautical pioneers; they frequently sought to revolutionise the very nature of powered flight. The following bizarre bestiary of resultant prototypes and experimental aircraft that flew from the ‘left bank’ of this radical thinking were often unique – and occasionally beyond comprehension, so we just had to find out more. Hugo Mark Michel and Joe Coles take a walk down the forbidden boulevard in search of France’s strangest flying machines.

10. The Fouga CM.88 « Gémeaux »

The Fouga CM.88 Gémeaux (Gemini), was a series of twin-engine flying engine test-beds developed in the 1950s to trial French jet engines. The strange appearance is the result of the fusion of two fuselages from the 1949 Fouga CM.8 Sylphe (the first 100% French jet aircraft). The twinning of an existing fuselage was a good design solution, proving cheaper and easier than developing a brand new aircraft. Its unusual W-shaped tailplane was formed by the fusing of two CM.8 V-tailplanes. As the engines to be tested on the aircraft were experimental, for safety reasons it was decided that the first Gémeaux model would be equipped with two engines, to ensure redundancy in case of failure. The French pilots were not used to landing a twin-engine twin-fuselaged aircraft, so to familiarize themselves, they were dispatched to the USA to train on the F-82 Twin Mustang. But, the French aircraft being a jet, this experience with a propeller aircraft was not very helpful. On 6 November 1951, the second Gémeaux produced became the first aircraft in the world to fly with a turbofan engine*, an Aspin I. The aircraft, built in two copies, had a very short but rich career testing no less than 5 new types of French jet engines. So, on 6 March 1951, the first CM.88 took to the skies, powered by two Turbomeca Pimene engines. The first flights went very well, the aircraft proved both stable and manoeuvrable, albeit with very rough landing characteristics.

(*British aviation historians may be of a different opinion on this)

9. SNCASO Sud-Ouest Delta VX Deltaviex

The extremely attractive SNCASO Sud-Ouest Delta VX Deltaviex was a small experimental jet aircraft built and tested in the 1950s. Despite its name, it was not equipped with a delta wing – but with a very small swept wing raked back at a dramatic 70°. The whole aircraft was tiny, with a wingspan of only 3.4 meters. It was a flying testbed, for a control system using the gases expelled by the engine on the control surfaces (blown flaps were also tested on the Bréguet 960 Vultur, a French Westland Wyvern equivalent). Around 2% of the gases produced by the engine were used to blow the trailing edges of the landing flaps. This system increased lift while stabilising the roll, and allowed a yaw control, replacing the traditional rudder. Thanks to its compact dimensions, it was possible to test it directly in wind tunnels to measure its characteristics precisely, and it was tested in the Chalais-Meudon and Modanee wind tunnels. After this test campaign, the Deltaviex started to make some very short flights, its only test pilot, Robert Fouquet, declared that it was a safe aircraft which controlled itself very well in flight, despite this, it could never make a real extended flight. This was simply too dangerous. Due to its size, it was impossible to install an ejection seat, and in the event of a failure of its single engine, the aircraft would have become uncontrollable and would have left no chance of survival for its pilot. Built in 1953, its existence remained a secret until 1956, when it was presented to the public.

Its poor carcass was saved in 1984 by the Ailes Ancienne de Toulouse where it was gradually restored.

8. Nord.500 « Cadet »

The Nord-Aviation N.500 Cadet was one of the many experimental ADAV (VTOL to English-speakers) research aircraft built in France during the ‘60s. Its basic configuration was similar to the Canadian CL-84 or US XC-142 ‘tilt-wings’ of the same period – and it was developed at the request of the French armed forces. The French military wished to replace helicopters and conventional fixed-wing military transports with fast vertical take-off and landing aircraft. The role of the Cadet was to test and develop, on behalf of SNCAN (becoming Nord-Aviation in ‘58), the new technology of tilt-rotor ducted propellers. Even before the first test of the prototype, Nord Aviation planned to cancel this unlikely project that they had reluctantly inherited.

After the presentation of a model at the 1965 Paris Air Show, two prototypes were assembled in 1967, powered by two 320-hp Allison turbines. The second prototype flew on July 23 1968 in captive flight (attached to the ground by strong steel cables to limit the risk of accidents) – though the world was too distracted by the PLO’s first hijacking of an El Al airliner to pay much attention. The N.500 Cadet made its first and only free flight in 1969, but never made the transition from vertical to horizontal flight. The programme was scrapped in 1971, despite the promise of larger and more powerful versions. The government preferred conventional helicopters, and instead opted for the rather boring Sud-Aviation SA-330 Puma instead.

Though it never entered service, it was probably the inspiration for the fictional Hunter-Killer drones of the Terminator movies, and the ducted fan VTOL concept has never gone away appearing on a multitude of unmanned aircraft and personal transport concepts.

7. Makhonine « Mak-10 » The Flying Extendable Dining Table

Several notable Russian aircraft designers fled to the west following the Russian Revolution of 1917. Sikorsky and Seversky were two of these emigres, and they founded Sikorsky and Republic respectively, two giants of US aviation, but Makhonine – a rather complex individual – took his unusual ideas to France.

By 1931 Ivan Makhonine, was a French nationalised engineer, working on a variable surface wing system (think flying extendable dining table). For take-off, economical cruise and landing the wings of his aircraft were fully extended, for high-speed flight the wing could be telescoped into the thicker inner wing section to reduce drag and lifting surface. In the extended configuration the wingspan gained eight metres.

The whole system was pneumatically operated and was coupled to a manual back-up system. To test his concept, Ivan Makhonine built a large single-engine monoplane equipped with the telescopic wing, the Mak-10 (not to be confused with the MAC-10 submachine gun beloved by Miami gangsters in 1980s movies). It flew for the first time on 11 August 1931, demonstrating that such a wing type could work.

It was nevertheless, like many French aircraft of the time, underpowered. Its twelve-cylinder Lorraine 12Eb engine was enough for such a large aircraft. A second version of the aircraft, the Mak-101, was built at the end of the ’30s to further studies of such an aircraft. The 101 was far more modern, equipped with an enclosed cockpit, retractable landing gear and a Gnome-Rhône 14K Mistral Major engine allowing it to reach 380 km/h. However, before the aircraft could begin its test campaign, the Second World War broke out, and the aircraft was captured by the Germans military. The aircraft was repainted in the colours of the Third Reich and transferred the aircraft to Germany for further tests. Its fate is unknown.

6. Carmier-Arnoux Simplex

From the very beginning of aviation history, French aeronautical engineer René Arnoux was seduced by the promise of flying wing (or tailless) aircraft. Whereas Johnny-come-lately Charles Fauvel (who did not start work until the mid-1920s) is rather better known, Mr Arnoux was an early pioneer who is largely forgotten. He built his first tailless biplane in 1909, followed by a monoplane three years later. During the 1913 Paris Air Show at the Grand Palais, Mr Arnoux exhibited the ‘Stablavion’. Despite its name, this was not a knife-crime-themed rollercoaster, but a two-seater low-wing monoplane powered by a 55-hp engine. The aircraft failed to attract any orders, despite the great hunger for military aeroplanes in the Great War. After the war, Arnoux resumed his research, and produced a second tailless biplane – and founded his company, the Société des Avions Simplex around 1921. The first aircraft produced by this new company was the Carmier-Arnoux Simplex, an extremely elegant tailless racing monoplane. It had a very round, sweeping shape and was powered by a 320-hp Hispano-Suiza engine. It was built to win the Deutsch Cup of 1922, and the prototype managed to reach an unprecedented 385 km/h during tests, far faster than the contemporary official world air speed of 330 km/h.

The piloting of such a machine was made very complex not because of its flying wing formula, but because the pilot couldn’t see very much at all; a cylindrical radiator was located just in front of the open cockpit blocking the forward view and the wide wings prevented any vision towards the ground. Even for a racing aeroplane, the pilot suffered a poor field of regard. A few days before its participation in the 1922 Deutsch Cup, the aeroplane had a serious accident, injuring its pilot Georges Madon. Discouraged by several accidents involving his aircraft, René Arnoux eventually ceased his activity as an aircraft manufacturer.

5. Gerin V-6E « Varivol » Monsieur extensible

The prestigious Coupe Deutsch de la Meurthe was a high-speed race that spurred a bounty of technological innovations in the 1930s, the first retractable landing gear and the first variable pitch propellers among many others. The first variable-surface wing was developed in pursuit of greater speed for the race. This system, although very simple, was nevertheless very heavy. Jacques Gérin’s idea was to divide the wing into two parts, a collapsible part, converted into a flexible covering capable of rolling up on axis, and a more conventional rigid part acting as a wing during high-speed flight. The soft part was stiffened by a system of sliding spars and ribs. In 1936, Gérin had an experimental biplane built to test this new technology.

This system allowed the upper wing to go from a surface area of 6.30 m2 to 26 m2 with the wing fully unfolded, thus reducing drag and theoretically increasing speed, manoeuvrability and handling characteristics during the take-off and landing phases. After a few flights and the destruction of the plane in an accident, work began on a racer derivative. The resultant Gérin V-6E Varivol was completed in 1938. The aircraft looked, at first glance, quite traditional for a racing plane of that time, but it was much more complex than it looked. After wind tunnel testing, the plane was in the process of finishing its development when the War began. Panicked by the German invasion of France, the engineers hid the plane in a barn where it was forgotten for many decades. It was later re-discovered and was restored by the Angers Marcé air museum. It was a very beautiful plane that unfortunately never flew. Its story bears interesting comparison with another beautiful aeroplane, the Bugatti 100P.

4. The Payen « Fléchair »

While the German aerodynamicist Alexander Lippisch swans around the green room of aviation history, sipping martinis and boasting about his pioneering work on delta wings, the French engineer Nicolas Roland Payen modestly sits in the shadows cradling his pastis and bemoaning the peculiarities of fate. Often overlooked, Payen nevertheless was the French father of the delta wing, and in turn the magnificent Mirage and today’s euro-canards.

In November 1931, when he was only 17 years old, he patented the Avion Autoplan, a delta-wing aircraft, but it was in 1935, the year he turned 22, that he designed and built the world’s first true delta-wing aircraft, the PA-100 Fléchair. The PA-100 was unique for its time and remains so even today: Its main wing was a delta wing with flaps to ensure stability during low-speed flight, with two small wings (then known as “machutes”) installed at the front of the airframe to ensure control of the aircraft at low speed (this type of small forward wing will later be known as a ‘canard’ and will be fitted on many delta jets such as the Dassault Rafale, the XB-70 Valkyrie and the Saab Sk 37 Viggen).

The PA-100 with its 180 hp Régnier in-line engine proved to be extremely underpowered, and failed to reach the high speeds required for the wing to be completely effecient. It was after a few flips and a crash on 27 April 1935 that a second prototype named PA-101 was built to take part in the French speed race, the Coupe Deutsch de la Meurthe. The new aircraft had the same overall characteristics as the Pa-100, but this time was equipped with the far meatier 380 horsepower Gnome-Rhône engine of 380 hp of 19 litres. It was the engine’s large displacement that prevented it from taking part in the race, as only aircraft with engines of less than eight litres were allowed to compete. The plane become instead a fairground attraction and was gradually forgotten. The last Payen delta was the PA-22, an experimental aircraft built in 1939 and originally powered by a Melot 1R ramjet. The aircraft was later converted to a conventional engine, the 180 hp six-cylinder Regnier. The aircraft had not yet flown when Germany invaded France in 1940, and the Germans, intrigued by the machine, decided to complete the wind tunnel tests.

After being repainted in German colours, the aircraft was transferred to Villacoublay and in October 1942, pilot Jacques Charpentier made the first flight. An extensive test programme was then launched, but before it was completed, Mr Payen managed to get his aircraft out of the hands of the occupiers, by claiming that modifications were necessary he sent the prototype back to his factory in Juvisy. Continued improvements included a new propeller, this time with variable pitch and additional fuel tanks, but in 1943 an Allied air raid on the Juvisy marshalling yard hit the factory, destroying the PA-22.

The PA-61 of 1965
The PA-61 of 1965

Nicolas Rolland-Payen’s legacy is undeniable today, in addition to the paternity of the delta wing, one of his many great ideas was harnessed by the Space Shuttle. The Shuttle’s rudder neatly split open in two to deploy an airbrake mode, a technology patented and tested by Mr Payen in the late 1940s and early 1950s.

3. The Riout 102T « Alerion »

Since ancient times, birds have been fucking with humans by suggesting to the naive that flapping is a good propulsion technique to emulate. As humans distractedly considered this absurd proposition, birds successfully stole our chips and shat on our car (or carts). Some people couldn’t escape the appeal of flapping machines (ornithopters) and wasted their lives in pursuit of the flapping dream. French engineer René Louis Riout built his first flapping wing aircraft in 1913, the DuBois-Riout. He managed to get the machine off the ground in 1916, but it crashed almost immediately and was condemned to join the eternally rolling montage of disintegrating early flying machines usually accompanied by jaunty comical piano music. Undeterred, Réné Riout continued to develop concepts for flapping-wing aircraft. He built larger and larger models until one day he proposed his ideas to the Service Technique de l’Aéronautique. The latter, interested in the engineer’s strange ideas, agreed to the development of an experimental prototype. And so, the Riout 102T Alerion was born (or hatched). Its fuselage was made of tubular steel and covered with aluminium. The closed cockpit was located at the very front of the machine, in the nose and the engine, a small V-twin engine was installed behind the pilot and the attachment point of the four flapping wings. The aircraft was equipped with four small retractable wheels and four wings operating in pairs. By early 1938, construction of the Alerion was completed and it was moved to Chalais-Meudon (an aeronautical research and development centre to the southwest of Paris). A campaign of wind tunnel testing began with the wings stationary, then later flapping, before the final stage of deformation was tested (it is this deformation that produces a thrust to propel the aircraft). The tiny fragile wings gave way under the rigours of the wind tunnel combined with the violence of the flapping. The damaged machine was not repaired, as there was no financial incentive to complete the development – and it never flew. Miraculously preserved, it is now on display in the Angers-Marcé Aviation Museum as a stylishly melancholy reminder that birds are arseholes.

2. Blériot 125 ‘Plantureuse Pauline

In 1928, the Blériot company created a modern airliner, that looked – and still looks – like nothing else, the rather busty Blériot 125. The specifications called for a passenger aircraft that could carry between ten and twelve passengers over a range of 1000 kilometres. The aircraft was distinguished by the presence of two passenger cabins and a central cockpit, making it a double-beam aircraft. The two massive pods have been compared to both clown shoes and breasts, perhaps giving insights into the different preoccupations of different observers.  

 The 125 was powered by two Hispano-Suiza 12HBr inline engines installed in a push-pull configuration that was rather unusual for the time. It was at the Grand Palais Air Show in Paris in 1930 that the aircraft was presented to the public for the first time. Although there was no aesthetic standard for the perfect design of an airliner as there is today, visitors were surprised by its strange configuration. An American press correspondent cruelly called the twin-engine aircraft a “Flying Joke” – despite his complete lack of knowledge of the aircraft’s performance in the air. For that, it was necessary to wait for the first flight on March 9, 1931. The ‘Flying Joke’ actually had relatively good flying characteristics and was fairly easy to fly. However, its single radiator was insufficient to cool two engines and its thick, asymmetrical, double-beam wing proved rather draggy. But it was not these minor shortcomings, but its unorthodox aesthetics that was to draw the most criticism. Nobody, from the civilian or military world, was interested in ordering this promising machine, whether this was the result of misogyny or just fear of clowns we will never know.

  1. The « Chrysalide » Papin and Rouilly’s Gyroptère

Seemingly a biz-jet designed by H. R. Giger to take him to the depths of Hieronymus Bosch’s hell, let’s meet the utterly unlikely Gyroptère. Engineers Papin and Rouilly created a sort-of helicopter whose flight technique was directly inspired by the fall of the samaras, the winged seeds of the sycamore tree.

It consisted of a single rotating 17-metre-long blade driven by a tip-jet of compressed air, produced by a 80-horsepower Rhone rotary engine driving a compressor. The engine also served, as a counterweight to the blade. The pilot sat at the centre of gravity in a small gondola which was stabilised from the rotation of the blade by a second jet of compressed air. Prayers would seem mandatory for the test pilot strapped to this massive mechanical spinning Edwardian sword.

The configuration allowed, in (the quite likely) case of failure, the pilot to gently lower the machine back to the surface of the water…at least in theory. A prototype was built in 1913, but tests were delayed by both a troubled development and the outbreak of the First World War, and the machine did not make its first attempt to take off until March 1915, from the Cercey reservoir in France. After starting the engine, the canopy began to turn and the machine took off and left the water for a short time before becoming violently unstable. The weird craft hit the surface of the water and sank.

Sure of their machine, despite unconvinced military observers, Papin and Rouilly persisted in hunting for finance for this bizarre project until they finally gave up in 1936.

Though unsuccessful, the Gyroptère was the first rotary craft to use tip-jets without any mechanical link between the rotor and the engine. It was not until the 1950s with the arrival of the SNCASO SO.1221 ‘Djinn’, that principle of tip-jets was to find application on a production aircraft. The overall Gyroptère concept was a technological cul-de-sac, but a fascinating vision of another universe where the giant mechanical tomahawk was a viable form of transport.

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