A tech adventurer

Andreea Cel Mare

Note 1

The documents in the Coandă Archive, in the custody of the National Museum of Romanian Aviation, have been made available to us through the kind permission of Mr. Dan Antoniu.

Note 2

Coandă's experiments with prefabrication have been extensively treated in his doctoral thesis 1921-2021: Prefabrication of housing construction in Romania, to be published by Ozalid Publishing House (volume in preparation).

Note 3

The different way in which Coandă's innovations were received in Romania and France has been studied in a broader comparison of the contexts in the two countries in the 1920s, from the perspective of professional ideologies and public housing policies - see Andreea Cel Mare, "Henri Coandă's Prefabricated Dwellings Between France
and Romania," sITA, vol. 6 Politics/Two Much or Not Enough (2018): 41-59.

He was always agifted and inventive boy, not too scrupulous I think, but irresistible as a way of being andattractive, full oflife, ideas,inventions and on top of that good-looking.
Note in Queen Marie's diary, 1923

Henri Coandă was born in Bucharest in the spring of 1886, but before he was six months old, the family moved to Vienna and then to Paris, spending their summer vacations in Ostanda on the windy beaches of the North Sea.
When he was just three, he accompanied his father to the inauguration of the Eiffel Tower, climbing to the platform 305 meters above the ground.
In Paris, during his pre-school years, he had Jacques, one of the nephews of the French diplomat and entrepreneur Ferdinand de Leseps, after whom the Suez and Panama canals are named, as a playmate.
When his father's mission as military attaché in France ended, the family returned to the country and Henri spent his early school years as a pupil at the Petrache Poenaru Municipal School in Bucharest. In 1897 he became a pupil at St. Sava High School, where he did not shine in any subject, with averages ranging from 5 to 9.
After three classes at "Sava" he entered the Military High School in Iasi, where he had the historian A.. D. Xenopol, and graduated at the top of his class in 1903. Also at Iași, he excels in theory and gymnastics, and stands out in the high school orchestra as a good cellist.
As a teenager, he spends three weeks of vacation on board the liner Dobrogea with his brother Petru, sailing the seas of the world.
He enrolled at the artillery, engineer and navy officers' school in Bucharest, which operated on Calea Griviței, and was sent to an artillery regiment in Germany.
He becomes a student at the Polytechnic(Technische Hochschule) in Charlottenburg, graduating with a doctorate in engineering sciences. In Berlin, he studies Otto Lilienthal's planar designs and takes sculpture lessons with Rudolf Marcuse.
In 1906 he began postgraduate studies at the Montefiore Electrotechnical Institute in Liège. In the workshop of a Belgian coachbuilder, he builds a glider, which he then tries out. In 1907, he exhibited a model of a propellerless biplane at the Salon des Expositions held in the Sports Palace in Berlin, but it did not attract the attention of specialists or the public.
On his return to Paris, with the support of Paul Peinleve, Gustave Eiffel and Captain Ferber, he obtained approval to mount a study platform on a locomotive on the Paris-Saint Quentin railway line. With the locomotive moving at 95 km/h, he carries out direct aerodynamic tests under real-life conditions on models of airfoils with various curves for aeronautical construction.
He enrolled at the Ecole Superieure d'Aeronautique et des Constructions Mecaniques in Paris, where he graduated in 1909 at the top of his class.
He studies sculpture in Rodin's studio, but abandons his great passion after meeting Brâncuși and realizing that he "can't keep up" with his art.
In 1910, at the Second International Paris Air Show, he exhibited a biplane with a propellerless propeller, which was a great success thanks to its novelty in design and construction. In the winter of the same year, he tried to fly the aircraft he had invented on the field at Issy les Moulineux, but as soon as it lifted off the ground, the wooden fuselage caught fire and the aircraft crashed. Coanda escaped with only a fractured left forearm, but he will never play the cello again. The catastrophic take-off revealed to the young engineer a strange phenomenon: the exhaust flames, instead of being directed directly behind the aircraft, spread across the entire fuselage. This emblematic moment marked the beginning of a feverish scientific and technical activity in fields as varied as aerodynamics, military logistics, construction, agriculture, ecology and so on, which would be marked throughout by important innovations and resounding failures.
Coandă's adventures in the world of technology were coupled with hobbies that were no less interesting: he played the cello in his high school orchestra and in a chamber quartet in Iasi and in the Imperial Orchestra in Berlin, he did artistic modeling and sculpture in Iasi, Berlin and Migné-Auxances, he practiced several sports, was a keen horseman, bred rare-breed dogs and kept a black panther as a pet.
The ease with which he moved from one field to another and his immense curiosity for all aspects of life reveal an open, rebellious mind and a childlike spirit that the Romanian engineer and inventor kept alert until the end of his life.

BRIEF

February 1921, cutting from a newspaper based on Sărindar Street

REINFORCED CONCRETE HOUSES

Rebuilding Dobrogea in two and a half years. Construction of bridges and roads. An aerial railroad with wagons and engine.
D. I. C. Atanasiu, the Minister of the Refacerei, received a very interesting offer from Mr. Engineer Coandă, son of Mr. General Coandă, President of the Senate.
Mr. Engineer Coandă - well known in the scientific world for his discoveries - proposed to rebuild the entire Dobroge in 30 months (two and a half years) with his own material, transported by his own means.
Five thousand houses would be built in reinforced concrete, using a new process that makes the walls waterproof and gives them the desired color, imitating marble.
The houses will each have three rooms and a loft with two bedrooms, kitchen, bathroom and closet.
The roof will be made of a type of tile made from wood shavings and cement.
The transportation of the special machinery and material to Constanta and from there to the localities where the building is to be done, concern the bidder. To this end, he undertakes to repair the roads and to make new ones where necessary - throughout Dobroge, building reinforced concrete bridges and bridges everywhere. All these will have to be practicable for the trucks that he is bringing in for the work.
At the same time Mr. Coandă submitted a plan for the construction of a network of overhead railways (I could not find out the technical name) with motor cars. This network would start from the city of Constanța and branch out in all directions of Dobrogea. It will now be used for the transportation of cement and, once the work is completed, it will be handed over to the State, with all the material it will have at its disposal, and will be used to transport grain for export from the villages of Dobrogea to Constanta.
The cost of a house is 20-25 thousand lei.
As this construction system is a mass construction system - the price would decrease as the number of buildings increases.
With this in mind, we learn that there are simultaneous talks on the construction of new neighborhoods - with systematic reinforced concrete houses, in the capital and other overpopulated centers.
The offer for reconstruction has been sent by Minister Atanasiu to the technical commission of the Undersecretariat for Rebuilding. This commission is composed of Mr. Antonescu, Mr. Ștefănescu, Mr. Lăzărescu, architects and engineer Răileanu, director of the new works.
As soon as the technical commission gives its opinion, Minister Atanasiu will bring the matter to the Council of Ministers.
As a point of detail, we may add that Mr. Coandă has, on behalf of the French government, the concession for similar constructions throughout Morocco.

Rail, road and reinforced concrete tanks

Oil played a crucial role in the First World War. For the first time in history, the governments of the countries involved in the conflagration were becoming aware of the strategic and economic importance of this liquid raw material, which was proving indispensable to the functioning of the military apparatus: the first armored vehicles had appeared, combat aircraft were coming into action, and the transport of troops and supplies to the front was beginning to be motorized.
At the outbreak of the conflict, France depended entirely on foreign oil1; in the absence of its own resources, supplies were provided by a cartel of importers strictly controlled by Standard Oil2, which dominated the world market at the time. While in the early years of the conflict the quantities supplied were sufficient to meet civilian and military needs, from 1916 onwards the progressive mechanization of the army (air force and land forces) led to an unprecedented increase in the need for fuel at the front, and the oil fleet made available to the importers' syndicate was no longer able to meet the demand3. By 1917, there was already a crisis in army supplies, a crisis aggravated by German U-boat attacks on American oil tankers crossing the Atlantic4.
The inability of the oil companies to meet the growing needs of the army and civil society prompted the French governments to equip themselves with the legislative and regulatory means to control the internal market. Oil activities had to be coordinated and centralized. New control bodies were created from 1917 onwards to facilitate state intervention in the oil sector. The authorities required the major refiners to standardize packaging, tank wagons and warehouses5.
At the same time, the shortage of steel, a material so necessary for the front, meant that reinforced concrete rapidly took its place in construction, giving rise to a strong stream of innovation.
By the first decade of the 20th century, reinforced concrete had proved its versatility in construction. Its use enabled the construction of continuous surfaces with complex geometries. The new material's simplicity and speed of construction, superior strength and non-combustibility quickly extended its field of application beyond civil construction. Between 1910-1914, reinforced concrete barges were designed and built in Germany, Great Britain, the Netherlands and the United States; in 1917, Norway launched the first self-propelled ship built of the same material6.
In response to the authorities' call for safe solutions for the transportation of liquid fuel, the young engineer Coandă, who was living in Paris at the time, relied on the versatility of reinforced concrete to build rail and road tankers. On May 18, 1917, he applied for a patent for a tank wagon whose constituent parts (chassis, platform and the tank itself) were made of reinforced concrete to form a monolithic structure.
The patent claims an "improvement in the construction of freight wagons, in particular tank wagons, characterized by the construction of a metal framework composed of the main parts of the wagon: chassis, platform, tank, etc., in such a way as to form a single element, which is then covered with concrete, with or without formwork, to form a monolithic block. The dome or any other ferrule attached to the metal framework is embedded in the concrete to serve as a tensile, shock and suspension device".
For easy cleaning, the inner surface of the tank was vitrified, allowing it to be washed with a steam or water jet.
In order to exploit his invention in France, Belgium and Romania, Henri Coandă set up the company "Transports, Canalisations et Distributions des Liquides" with a group of French engineers and industrialists. In the following years, the reinforced concrete tank wagon was patented in Great Britain and the United States7.
The invention was commercially exploited, as shown by the photographs available in the archive, but there is no information about who benefited from the wagons or where they were built.
On the side of a "patented S.G.D.G." tankwagon8, one can read "Batignolles attachment point".

Description of the manufacturing process:
Askeletonismade which constitutes at the same time the chassis, the platform and the tank (a).
The ribs (b) on the sides of the tank (a) act assuspensionarmson the springs (c) of thewheels(d).
Next, the longitudinal beams (e) are fitted, whichform the longitudinal members of thechassis and at the same timesupport all the other parts of the assembly.
At thetop of the wagon a dome (f) ismade for filling and manholes.
Concrete, with orwithout formwork, ispouredover themetalskeleton thusprepared, thusobtaininga monolith.
The couplings and other fittings of thetowing, ramming and suspension devicesare embedded in the concrete.
On the outside, thesurface of the tank isreinforced with one or more ribs (g), which may be continued inside the container bywallsintendedtocounteract the deformation of the tank in thelongitudinal direction.

The Coandă archive also preserves a 1:20 scale project of a tank wagon.
Coandă continued to seek new applications for reinforced concrete and designed road tankers.
On October 15, 1919, he submits the documentation for the patent for a reinforced concrete tank wagon, consisting of a monolithic structure, with the following description: thesupportingchassisconnecting the tank to the undercarriage is removed; the tank itselfis the chassisfor attaching the suspension to the undercarriage.The suspension springs are fixed directly to thereinforced concretesupports, which are integral with the tank. The weight of thereinforcementisincreased at thebottom of the tank to give itadequate resistanceto the bending stresses andforcesexerted by the suspension components.The sidesupports,whichare integral with the tank, serve to fix the springs of therearwheelaxle, whichrest by means of shock-absorbers on a stop at thebottom of the tank,whichis also integral with it.
This type of tanker can be seen in one of the photographs of the Paris construction site, where Coandă applied the construction method based on prefabricated semicircular reinforced concrete elements, a method which will be described later.

On May 20, 1920, Coandă submits documentation for the patent of a container for the storage and transportation of food liquids, obtained by assembling prefabricated reinforced concrete elements (fig. 13). The three components of the container are assembled using metal parts. The joints between the parts are sealed with aluminized cement and protected by a circular metal 'U' profile.
After the war, the French steel industry recovered and made significant progress and production capacity gradually increased. Steel rapidly regained its fields of application and reinforced concrete tanks and cisterns were no longer of interest.

NOTES

1. Pierre Fontaine, L'Aventure du petrole français (Paris: Nouvelles Editions Latine, 1967).

2. Standard Oil Company and Trust: oil cartel, the empire of industrialist John D. Rockefeller and his associates; in the first decade of the 20th century it controlled almost all production, processing, marketing and transportation of petroleum products in the United States and dominated the world oil market. After the dissolution of the empire in 1911, eight North American companies retained the name "Standard Oil".

3. Daniel Murat, L'Intervention de l'état dans le secteur pétrolier en France (Paris: Technip, 1969).
4. German torpedoes and mines sank six tankers and damaged eight others.
5. Daniel Murat, op. cit.
6. The Norwegian engineer Nikolay Knudzon Fougner was involved in 1910 in the Philippine Islands in the construction of a harbor barge with a reinforced concrete hull; in the early years of the war, he was convinced that the many ships sunk by German U-boats could be replaced quickly and relatively cheaply by concrete vessels and convinced the Norwegian authorities that a self-propelled, reinforced concrete, heavy lift vessel was worth building. Thus, on August 2, 1917, the Namsenfjord, with a capacity of 200 tons and a length of 25 m, was launched.

7. Patent GB 116,100 and US 1,276,621.
8. Abbreviation for Breveté Sans Garantie Du Gouvernement (patentedwithoutgovernmentguarantee).

Cable airplanes?

In the French mountain regions, tourism originated in the late 18th century. At first, it was only practiced in the summer season for medical reasons (treatment of rheumatism, pneumonia and other ailments in thermal and climatic resorts), scientific reasons (flora and fauna observation) or sporting reasons (mountaineering). Skiing began to be practiced by a growing number of tourists, making the resorts popular all year round1.
Thanks to exclusive tourism, the Côte d'Azur entered the 20th century prosperous and with a booming economy. The region attracts a growing number of wealthy holidaymakers, delighted by the mild, sunny year-round climate and the rugged peaks of the Maritime Alps, with heights of over 3,000m. The Côte d'Azur, especially in winter, is beginning to face a growing population on the move, always on the move, keen to try new and daring sports.
On the eve of the First World War, more than 150,000 people were spending the winter in cosmopolitan Nice, with French, English, German, Russian, German, Swiss and English nationalities most represented2.
After the war, a number of small high-altitude mountain resorts were transformed into real resorts for the new sports and developed an appropriate infrastructure of land transportation, accommodation and leisure facilities. The solution to the problems of accessibility required huge efforts and the involvement of an impressive number of engineers and inventors whose theories and techniques paved the way for the modern cableway3.
Among the ingenious and daring means devised to make it possible to conquer Europe's most inaccessible peaks was an invention by Henri Coandă.
In March 1919, the young engineer applied for a patent for an "aerial transporter for the transportation of persons or goods", which would have reached very high speeds in complete safety.
It should be noted that, at that time, there was no cableway in operation in France for passenger transport. In fact, the first "passenger cableway", on which work began in 1909, was not inaugurated until December 1923 at Chamonix - Aiguille du Midi4. The systems then in use by the army or the mining industry generally transported materials over short distances at limited speed and consisted of nacelles suspended from a cable forming a track, towed by a second cable driven by a motor on the ground.
The first cableway installation to ensure high tensioning of the hauling cable, and which was to become the standard in the years to come, was put into service in October 1923 in the Italian Alps: the Merano-Avelengo cableway, designed by Luis Zuegg5.
In 1919, Coandă came up with a radical solution that completely changed the operating principle of this type of installation by doing away with the towing cable.
As described in the patent, Coandă's transporter, fitted with one or more propeller propellers, was connected by rigid rods to a running assembly consisting of one or more rollers; the running cable served as a conductor for the power supply to the motor driving the propellers, via a flexible conductor. Parallel to this cable was a second conductor cable, on which ran an auxiliary reel, connected by a flexible conductor to the same motor, to close the circuit. In order to prevent the cab from collapsing in the event of a break in the running cable, one design variant provided for one or more additional cables to be laid under the main cable in the same plane as the main cable.
Subsequent patents sought to improve the design of the cab and the running gear in order to achieve better suspension and increase the stability of the assembly, and to tension the cable which formed the running track.
The additions led to the final form of the transportation system which Coandă proposed to the French authorities for the establishment of an airline on the Côte d'Azur and which would become known in the press as the "cable airplane".
In the following years the cable transporter was patented in England, Switzerland and the United States6.
On March 15, 1920, the inventor applied to the Prefecture of the Department of the Alpes-Maritimes for the concession of an aerial railway from Nice to Monte Carlo, with an extension to Peïra-Cava7. In the explanatory note accompanying the request, Coandă described his invention as an aerial means of transport which would offer the public all the advantages of an airplane: the cabins, with a capacity of up to 20 persons, would reach speeds of up to 200 km/h, at a time when cable air transport installations did not exceed 15 km/h, without the inherent risks of flying - the existence of the support point offering safety and stability. The line, 35 km long, would have made it possible to cover the distance between Nice and Monte Carlo in just 10 minutes.
The justification note also included a feasibility study assessing the cost of construction and operation, how this would be amortized, and details of the airline: the proposed number of sections, the duration of the entire route, the estimated number of flights per hour, the estimated number of passengers, the operating schedule according to the season, etc.
Coandă's proposal gained the interest of the authorities: in a letter dated May 29, 1920, the Prefect of the Maritime Alps sent Coandă an extract of the deliberations of the General Council of the Prefecture on the application for the concession, and the outcome of these deliberations. The General Council considers that the project appears to have been "seriously studied", proving to be of sufficient interest to the Department of the Maritime Alps, and expresses its confidence in Coandă's experience in the field of aviation. At the same time it draws attention to the safety concerns of the users, given the "enormous" speed at which they would have been traveling, and calls for the system to be tested by establishing a test line.
The Control Service engineers state that the safety measures are well designed - the line is generally long and straight, the 4 cables minimize the risk of the cab collapsing, the passage through the pylons seems to be well resolved and in case of a breakdown, intervention vehicles are provided to tow the faulty transporter - and also ask to verify these measures by running the test line.
In conclusion, the Works Commission proposes that the project be taken into consideration, on condition that one or two test lines are first carried out - and recommends that the file be sent immediately to the Ministry ofPublicWorks in order to obtain the necessary authorizations, in accordance with the laws in force at the time.
In June 1920, Coandă concluded an agreement with the company "Trefileries d'Angers"8 for the exclusive supply of metal cables. The company undertook to supply the cables needed for the test section9 free of charge.
There followed a period of almost a year not covered by the documents available in the archives.
In the meantime, Coandă had succeeded in enlisting the well-known General Jean-Baptiste Estienne, the pioneer of French military aviation and "father of tanks", who became "general agent" for the Maritime Alps region of the company "Transporteurs Modernes sur Cables"10.
The minutes of thedeliberationsof theMunicipal Council of the commune of Luceram11 of March 15, 1921, which resulted in the conclusion of an agreement between the commune of Luceram and the company "Transporteurs Modernes sur Cables", record the mayor's view that the new air transport "would open a new era of prosperity for the region". The city council considers the project to be "in the general interest" and, like all progress, should be "encouraged and facilitated".
In an agreement with the commune of Luceram, signed on 7 April 1921, Coandă was authorized to set up a trial aerial route across seven communal lands designated by the town hall. The Commune grants him free of charge all the necessary authorizations for access to the communal land for the execution, maintenance, supervision and repair of the line and all the necessary permits for temporary construction, transport, installation, maintenance and repair of cables, transport and storage of materials and even authorizes the felling of some trees in the communal forests as a necessary measure for the construction of the pylons and the installation of the cables or as a safety measure for the overhead line to be installed. The municipality grants the sites of the future pylons, each of 200 square meters, free of charge and authorizes the overhead line and the conveyors to pass over the municipal roads. Coandă undertakes to maintain a clear height of 5 meters between the ground and the cabins. The agreement also lays down that a station will be set up to serve the commune when the line is put into service and the annual sum which Coandă undertakes to pay to the commune for the entire duration of the line's operation.
On 8 April 1921, the Mayor of Luceram's opinion was followed on 8 April 1921 by a decision of the Prefecture of the Maritime Alps authorizing the installation of an aerial line of 4 parallel cables in a vertical straight line from Luceram to Peïra-Cava, for testing 'self-propelled aircraft'.
On August 26, 1921, the prefect of the Maritime Alps endorsed the two documents described above, and the authorization file became complete, to be sent to the Ministry of Public Works.
The documents kept in the Coandă archives stop there. From the overview of Peïra-Cava, published on the Internet, we learn that in December 1921, the Ministry of the Interior and the Higher Council of Public Works refused the project12.
In Bucharest, probably in an attempt to recoup some of the company's losses, Coandă proposed to the Minister of Reconstruction the construction ofanetwork ofaerial railways with motorized wagons, which would have started from Constanța, branched out across Dobrogea and would have been used initially to transport building materials for the reconstruction of the region and then to transport grain from the territory to the port of Constanța.
Although Coandă is considered by some authors to be one of the forerunners of the modern cableway13, his cable transporter did not enjoy the notoriety of other inventions by the Romanian engineer.


NOTES

1. Bertrand Larique, "Les sports d'hiver en France : un développement conflictuel ? Histoire d'une innovation touristique (1890 - 1940) ", Flux, 2006/1-2 (n° 63-64), pp. 7-19. DOI: 10.3917/flux.063.0007. URL: https://www.cairn.info/revue-flux1-2006-1-page-7.htm
2. https://fr.wikipedia.org/wiki/Histoire_des_Alpes-Maritimes
3. At the beginning of the 20th century, the cable railway was called a "suspended railway" or "cable transporter"; in 1910, people in mountain regions were transported by "aerial funiculars". The term 'cable railway', used since the 1920s, derives from 'telepherage', which in the second half of the 19th century referred to the cable transportation system used in the mining industry (gr. "tele" - distance + "pherein" - to carry) and is integrated for the first time in the Larousse Dictionary in 1923 - Laurent Bernet, L'aventure du premier téléphérique de France - Chronique du premier téléphérique de l'Aiguille du Midi, dit "des Glaciers", à Chamonix-Mont-Blanc, (Editions des Rochers, 2012): 9.
4. The first cable car in France was inaugurated in December 1923 in L'Aiguille du Midi, Chamonix-Mont Blanc, on the occasion of the Chamonix Olympic Games, but due to technical problems the line did not become operational until July 1924 (Laurent Berne, op. cit., pp. 21-23).
5. The Merano-Avelengo cableway, designed by the Italian engineer Luis Zuegg and inaugurated in 1923, was equipped with a device for very high tensioning of the carrying cable - of the order of one third of the breaking load, thus significantly increasing wear resistance - and quickly established itself as the standard - Pierre-Louis Roy, L'Aiguille du Midi et l'invention du téléphérique, (Grenoble: Editions Glénat, 2004): pp. 91-95.

6. Patents UK 140,428 and 154,168, CH 93,952, US 1,344,677.

7. Locality situated in the Department of the Maritime Alps, at an altitude of 1,450 m; its proximity to the coast has made it an increasingly popular resort since the end of the 19th century, first in the summer season, then, with the spread of winter sports, all year round (Christian Helion, "Peïra-Cava: Itineraire d'un lieu touristique dans la moyenne montagne niçoise", Mappemonde, 2000/3, pp. 1-4).
8. Factory set up in 1906 as part of the Bessonneau Works in Angers, founded in 1901 by the French industrialist Julien Bessonneau, known for the portable wooden and canvas "Bessonneau hangars" used by the British Royal Air Force during the First World War.
9. A transcript of a letter to Coandă, signed Bessonneau, confirming the agreement between the two companies, has been preserved in the archives.
10. Jean-Baptiste Eugene Eugene Estienne (1860-1936): artillery general and military engineering specialist, one of the founders of modern French artillery and military aviation and creator of the French tank division. From the very beginning of his military career he proved to be particularly ingenious and receptive to innovation. (according to General Estienne's biography on the website Le char d'assaut en France - "Assault tanks in France" - lecharenfrance.canalblog.com).
11. Commune in the Department of the Alpes-Maritimes, situated at an altitude of 650 m and 27 km from Nice; Peïra-Cava is administratively subordinate to the commune of Luceram.
12. https://fr.wikipedia.org/wiki/Peïra-Cava
13. Pierre Montaz, L'aventure du transport parcâble - Une histoire, un avenir (FACIM: 2009).

The vault

After his experiments with reinforced concrete in the construction of rail and road tankers, Henri Coandă continued to exploit and perfect the technologies he had perfected, developing a rapid method for the mass production of economical housing.
"The HenriCoandăprocess consists inbuilding houses from reinforced concrete elements, executed in the immediate vicinity of theconstructionsite, which are assembled vertically for the walls, horizontally for thefloors and sloping for theroofs.These elements areplacedside by side and then ironed together.Afterthisoperation, a special 'Henri Coandă' concrete issprayed using asteam machine.
Oncethe concrete sprayingoperationisfinished, the entireconstruction becomes a reinforced concretemonolith .
The concrete elements usedare semi-cylindrical. The dimensions in length and thickness are afunction of the dimensions of theconstruction and therefore , of course, of the forces to be withstood."1
The advantages of this construction system were ensured by the low price (according to Coandă, "much lower than those built by ordinary methods of equal strength and size"), the speed of execution (a construction would be completed in one to ten weeks, depending on the complexity), good thermal insulation (houses are warm in winter and cool in summer) and low labor consumption (through the use of prefabricated elements and mechanization of the commissioning process).
On March 25, 1921, Coandă submits in France the documentation for the patenting of "Reinforced concrete elements for all types of construction".
The same process was subsequently patented in Great Britain2 and in the Kingdom of Serbia, Croatia and Slovenia3.
In order to produce the concrete for monolithizing the system, Coandă designs a special mixing and design machine, operating with steam under pressure. The "granite concrete" thus prepared and applied became waterproof and "almost instant setting", according to the inventor's description.
For the commercial exploitation of the method in France, Belgium and Romania, the companies studying the inventions patented up to that time ("Marbres", "Beton Granit", "Transport et Canalisation des Liquides") merged in February 1921 to form "Societé Anonime Établissements Henri Coandă". The company's aim was to deliver economical, mass-produced, low-cost housing on demand, with low labor and construction time, low consumption of wood and steel.
On the basis of correspondence and photographs preserved in the Coandă Archives, we have identified a house built under this system in Paris, in the 19th arrondissement, in the Place du Danube (today Rhin-et-Danube) area, probably in the Mouzaïa4 housing estate.
A rich correspondence between Henri Coandă and various representatives of the Romanian public authorities dating from the same period has survived, dealing with the post-war reconstruction and reconstruction work needed in the affected regions of the country, as well as the construction of social housing in Bucharest.
In February 1921, Coandă offered his company's services to the Undersecretary of State for Rehabilitation and Supply for the rebuilding of the entire Dobrogea region, by building 5,000 housing units, together with the necessary infrastructure works. Optionally, he also proposes the use of the aerial cable transporter patented in 1919, in a network extending over the entire territory, to supply construction sites with building materials, with the aim of making it a permanent means of transporting agricultural produce to the port towns once the works are completed. A first batch of 150 trial houses was to be built in the immediate vicinity of the Danube, near Cernavodă, as part of the Type A rural project. The cost of a house would have been 23,750 lei, to which would have been added 12% for transportation of materials5.
All walls will bebuiltin reinforced concrete,following the HenriCoandă system. Theface ofthe wallsfacing theinside of theatticswill bemade withwoodshavings,the wood dosagenever exceeding 80% of the volume of the concrete applied. All edges andcornerswill be rounded. Theconstructionwill bemade of elements prepared in thefactory or on the building sites, assembled and joined together, then walled and joined to each other by means of aspecialmachinecalled a 'granite concrete projector', the proportion of the concrete being 350 kg of Portland cement. These walls will have an internal void not exceeding 28 centimeters for the exterior walls. [...]
Thefloorswill be constructed in the same way as thewalls,that is to say,slabsmade inadvance and joined togetherby concrete applied at the time ofbuilding. Thefloorswill have tocarry anoverload of atleast 600 kg per square meter [...] [...].
Theroofshall be as asloping floor and constructed as such [...].
Window anddoorframes willalsobemade with a special concretemade withwoodsawdust. [...]
The special, semicircular elements whichenter intotheconstructionofthe walls,floors androofwill bemade with a dosage of 500 special Lafarge cement per cubic meter of concrete and reinforced with asteel wiremeshand three iron wires,twoof which of 8 mm and one of 6 mm. In addition,depending on thefunction to be performed, theiron wirereinforcementcould beincreased ordecreased.
In March 1921, the Undersecretariat of State for Rehabilitation and Supply was disbanded and the Ministry of Public Works took over the task of rehabilitating areas destroyed by the war.
Coandă continues to negotiate with the Ministry of Public Works, the Capital City Hall and the Ministry of Communications (for the C.F.R. Labor House).
In meetings on July 1, 5 and 19, 1921, chaired by Elie Radu, the Higher Technical Council examines the construction process:
TheCouncil, afterlisteningtoMr. Engineer HenriCoandă and thediscussionsthat took place ,
Consideringthat in principle the system proposed by Mr.Coandă is advantageous, as it allows a rapidconstruction of houses inwar-damagedregions,
Considering , however,that it is not yetknown how suchdwellingswould behave inour country from the point of view oftemperature variationsin winter and summer,sound, aesthetics, etc. , andthat it is therefore not prudent to contract from the outset anumber of one thousanddwellings, which would involve the State in anexpenditureof about 50 million,withoutknowing the practical results they will yield,
Consideringalsothat, in order to experiment the system ofconstructionproposed by Mr.Coandă, it is preferable to commit for thetime being the execution of only 100 houses at most,leavingthe rest of the houses that the State will needto be approvedafter theresults will beknown.[...]
If,after these first houses have been built, it is foundthat they have given good hygienic, economic and aesthetic results , the Ministry will be able to contract the remaining 900 housesprovided for in the specifications.6
As a result, in a letter dated July 30, 1921, the Minister of Public Works, Ion Petrovici, ordered Coandă to build a sample of 100 rural dwellings. Unfortunately, there is no documentation of their realization.
In Romania, the construction process with reinforced concrete semi-cylindrical elements was patented in September 1922, with the title "Henry Coandă's construction process" and the description "Construction of buildings made of reinforced concrete with the same element serving both compression and flexion, where the reinforcements and concrete make the total construction monolithic. Where the same simple formwork element can be used to build walls or floors or roofs [...]" (fig 15).
Coandă built at least one house in Bucharest using the patented method. Proof of this can be seen in an estimate drawn up by Coandă's company for a project in April 1923, based on the experience of a building site in progress at the time.
On December 18, 1923, Queen Marie records in her diary an audience with the young engineer Coandă:
He is nowengaged incheap concrete construction and has even built a model school, which he wantsme to visit. He has big plans for anundergroundrailroad inBucharest and God knows what else"7.
The Queen did not follow up on the invitation and we have not, to date, come across any other clues to Coandă's patented method of building in Bucharest.
Henri Coandă's experiments in prefabricated housing construction remain isolated in the Romanian landscape of the time, but they are thoroughly modern and perfectly synchronized with the concerns of the European and international professional environment in the period following the First World War.

NOTES

1. From the"HenriCoandă " description of processes and patentsapplicable toconstruction, available in the Coandă Archive.
2. UK 177.543.
3. SK 4.077.
4. Workers' housing estate designed by the French architect Paul-Casimir Fouquiau in 1901 on the site of a disused gypsum quarry. On narrow lots of approx. 4.5 m, the ground-floor and first-floor buildings of the same typology were built in different stages between 1901 and 1940.
5. According to correspondence kept in the Coandă Archive.
6. A.N.I.C., fonds M.L.P-C.T.S., file 60/1921: 243-245.
7. Regina Maria of Romania,DailyNotes, vol. V (București: Historia, 2007): 461.

French metal houses

In Western Europe, the idea of mass-produced housing took shape after the First World War, under the influence of pioneering industrialists, engineers and architects who, adopting Taylorism, Fordism and other American models of scientific management, set out to experiment with construction methods directly inspired by the extraordinary results achieved in the aeronautical, automobile and naval industries.
The ravages of war had aggravated the already precarious urban living conditions caused by the industrial revolution. Affordable housing became an emergency of the 1920s. European governments were looking for solutions to acute housing shortages at a time when the labor force remained in short supply. The first social housing programs were to provide a strong stimulus for innovation in housing construction.

Intensive efforts to solve the emergencies of the moment led to the adoption of innovative technical solutions in all countries affected by the conflagration. The war itself was a period of great advances in scientific knowledge. Major industrialists also sought to adapt wartime innovations to the peacetime economy, leading to an unprecedented diversification of construction techniques.
In French cities, the housing crisis, which had been felt since the end of the 19th century, worsened in the 1920s as a result of the destruction caused by the war and the influx of rural and foreign populations. The existing housing stock in Paris and neighboring regions became insufficient and unsanitary. At the beginning of 1927, demand for affordable housing in the French capital was 13 times greater than supply1.
Loucheur Law
Louis Loucheur2, a leading representative of the republican left, had been working since 1920 to find a solution to the housing crisis. His efforts were crowned with success on July 13, 1928, when the law making housing a national priority was passed. The law regulated state intervention in the financing of housing construction by providing long-term, low-interest loans to encourage home ownership.
The main requirement of the Loucheur Law was the low cost, not exceeding 45,000 francs, of a single-family house delivered turnkey. As a result, a contingency plan was put in place to build 200,000 HBM economic housing units and 60,000 ILM3 social housing units over the next five years throughout France, with state subsidy of up to 90% of the cost.
Technical Office for Steel Utilization (O.T.U.A.)
Although at the end of the third decade of the 20th century France was one of the world's largest steel producers (with 8,386,000 tons produced in 1927 alone), consumption had begun to fall significantly - demand for armaments and warships had almost disappeared, the rail network was almost completed throughout France, and reinforced concrete was gaining ground over steel in the construction of bridges, viaducts and major buildings. In 1929, the professional body O.T.U.A.(Office Technique pour l'Utilisation de l'Acier - Technical Office for the Use of Steel) was set up, with the main task of finding new ways of using steel. The O.T.T.U.A. launched a veritable propaganda campaign to stimulate steel consumption. One of its aims was to encourage experiments in steel construction, especially housing. It supported the efforts of private companies which exhibited at the Paris Fair in the spring of 1929 the first economical steel dwellings in accordance with the Loucheur program. The five steel house systems, including Henri Coandă's "multicellular" constructions, were documented in detail in the pages of "Acier", the publication of the O.T.U.A. organization, in issue No 2 of August 1929.

Forges et Ateliers de Commentry - Oissel

A skeleton-type system, based on a safe standard element, a rectangular steel frame 1 m thick and 2.5 m high, and light infill of aerated concrete blocks(aerocrete), providing good thermal insulation.
The steel frame was so light that it could be handled by one person.
The interior and exterior finishes gave the residential buildings a conventional appearance.

La MaisonIsotherme, Raoul Decourt

A lightweight steel structure supported the multilayered walls. The outer layer, a sort of reinforced concrete screen 5 cm thick, was obtained by spraying the concrete onto a metal mesh (torcreting); the operation was carried out from the inside. The supporting structure was also covered with concrete for corrosion protection. A second layer of natural agglomerates provided good thermal insulation. The generous air space between the two layers also contributed to the very good thermal behavior of the façade.

Société des Forges de Strasbourg

For Forges de Strasbourg, Adrien Brelet, André Ledonné and Oscar Nitzchké designed a metal structure for the Forges de Strasbourg consisting of standardized elements, mounted side by side and assembled by bolting. Thermal insulation was provided by natural fiber agglomerates, such as Heraclith (used for the prototype shown), Solomite, Celotex or even common plasterboard panels. The 1 mm thin sheets of sheet were stiffened by embossing. On the outside, the wall was closed with copper-coated steel sheeting, giving superior corrosion resistance.
The prototype proposed by Forges de Strasbourg was the only one of the five systems to exhibit the nature of the material from which it was made.

COMEFI, Ferdinand Fillod


The system proposed by Ferdinand Fillod consisted of double walls composed of two sides of 3 mm thick sheet metal, spaced 40 cm apart, connected by means of clips, without bolts or rivets, and lightweight insulating panels of straw or sawdust on the inside.
In the rooms, the walls could be painted or covered with wallpaper, and the outside was protected with several coats of anti-corrosive paint.

Multicellularconstructions, HenriCoandă


The multicellular element, as Coandă called it, made entirely of 0.4 mm thick laminated sheet steel, consisted of two walls connected by a zigzag-folded entret, forming triangular prismatic compartments. The edges of the element had beveled flanges, which served to connect the parts, to join them to another adjacent element and to stiffen them. All the sheet metal parts were joined by electric spot-welding to form a sort of beam with a cross-section of 280 x 250 mm and a length as required, e.g. 3 m. The multilayered elements were assembled by longitudinally joining the edges of the jointed edges to form panels, the joint also being welded. The panels were covered on both sides with a continuous insulating layer 3 cm thick, giving a total thickness of 340 mm. The panels thus formed became walls or planks and were joined together by means of dowels and anchors. At the corners, the walls were assembled together by means of grooves and monolithization. The panels for the entire construction were made in the factory and then transported to the construction site to be assembled on a foundation previously made on site.

Once finished inside and out, nothing betrayed the underlying material.
The 5 systems exhibited at the Paris Fair in 1929 aimed to mass-produce affordable housing, saving materials, labor and construction time, and reducing site work to simple assembly operations. Whatever the construction principle - metal frames and lightweight infills or complete walls made of thin sheet metal - they all ingeniously exploited the properties of steel (stiffness and strength to weight ratio) and cleverly used air as a means of thermal and sound insulation.
All five radical experiments responded to an established political and social agenda.
The prototypes on display attracted public interest and were commissioned by a large number of major public and private companies.
According to the press at the time, the metal houses promised to provide a rational solution to the housing problem while reconciling the country's economic and social interests.

Apart from their technical and architectural interest, the French metal houses, an experiment to which the Romanian Coandă also contributed, were the result of a happy meeting between public policy and professional ideologies and gave concrete form in steel to the modern aspiration to solve the problem of affordable housing by means of technological innovation.

NOTES

1. Marie-Jeanne Dumont, Le logement social à Paris 1850-1930 (Liège: Mardaga, 1991).
2. Louis Loucheur (1827-1931), French politician and engineer, deputy for the North (1919-1931), member of the radical left, minister of labor, hygiene, assistance and social security (1926-1930).
3. Immeuble à Loyer Moyen - a social housing building intended to be rented by persons whose income does not exceed a certain ceiling.