The Gnome engines
Gnome et Rhône was a major French aircraft engine manufacturer. Between 1914 and 1918 they produced 25,000 of their 9-cylinder
Delta and Le Rhône 110 hp (81 kW) rotary designs, while another 75,000 were produced by various licensees, powering the majority
of aircraft in the first half of the war on both sides of the conflict. In the post-war era they started a new design series
originally based on the Bristol Jupiter, but evolving into the 1,000 hp-class (750 kW) Gnome-Rhône 14K Mistral Major
radial, which was also licensed and used around the world during World War II. They were nationalized as a part of Snecma in
1949, but the brand lived on for a time as the manufacturer of motorcycles.
In 1900 the 26-year old French engineer Louis Seguin bought a license for the Gnom gas engine from the German firm Motorenfabrik
Oberursel. Sold under the French translation, the Gnome was a single-cylinder stationary engine of about 4 hp (3 kW) that ran on
kerosene (known in the U.K. and South Africa as paraffin) intended to be used in industrial applications. The Gnome used a unique
valve system with only one rod-operated exhaust valve, and a "hidden" intake valve located on the cylinder head.
On June 6, 1905 Louis Seguin and his brother Laurent formed the Société Des Moteurs Gnome (the Gnome motor company) to produce
automobile engines. They soon started development of one of the first purpose-designed aircraft engines, combining several Gnome
cylinders into a rotary engine. The design emerged in the spring of 1909 as the 7-cylinder rotary Gnome Omega, delivering 50 hp
(37 kW) from 75 kg. More than 1,700 of these engines would be built in France, along with license-built models in Germany, Sweden,
England, the USA and Russia. The Gnome powered Henry Farman's Farman III aircraft to take the world records for distance
and endurance, as well as powering the first aircraft to break 100 km/h, and powered France to become the leading country in aviation
for some time.
All of the Gnomes were known for their unique solutions to getting fuel to the top of the piston without using piping. Early
models used two valves, one in the cylinder head and a second embedded in the piston itself, they were counterweighted to open at the
end of the piston stroke. Without any springs or pushrods, the valve would pop open on the downstroke, allowing fuel to be drawn into
the cylinder from the crankcase area. Unfortunately it was also very difficult to service, requiring the cylinder to be disassembled.
In order to improve reliability and maintenance, later models used the Monosoupape (single-valve) system instead, using a single
exhaust valve at the top of the cylinder and using a series of ports to allow the fuel mixture into the cylinder when the piston
dropped far enough.
The basic Gnome design was then delivered in a series of larger engines. The Gnome Lambda of 1911 was a larger 80 hp (60 kW)
version of the Omega, followed by the 9-cylinder Gnome Delta - also called the Gnome Monosoupape as it used that engine design
approach for the first time - of 100 hp in 1914. Gnome also tried their hand at a 14-cylinder two-row version, the Double Lambda of
160 hp (120 kW), but this saw little use, even though it was copied by Oberursel as the U.III in Germany, and used in a few early
Fokker fighter designs without success. To deliver more power with the advent of high-power inline engines late in the war, a
completely new 9-cylinder Monosoupape design was delivered in 1918 as the Type-N, delivering 160 hp. This design saw use on the little
known but excellent Nieuport 28.
WWI ( Gnome joins Le Rhone )
Another French engineer, Louis Verdet, designed his own small rotary engine in 1910 which did not see much use. In 1912 he
delivered a larger 7-cylinder design, the 7C, which developed 70 hp from 90 kg. This proved much more popular and he formed Société
des Moteurs Le Rhône later that year. He soon followed the 7C with the larger Le Rhône 9C, a 9-cylinder design delivering 80 hp
(60 kW). Compared to the Gnome's, the Le Rhône was considerably more "conventional", using copper pipes to bring the fuel to the top
of the engine, along with intake and exhaust valves. Like Gnome, the Le Rhône designs were widely licensed, in this case the 9C was
being produced in Germany (by Oberursel, whose Le Rhone engine copies received an "Ur." prefix), Austria, England and Sweden.
Gnome et Rhône
After several years of fierce competition, Gnome and Le Rhône finally decided to merge. Negotiations started in 1914, and on
January 12, 1915, Gnome purchased control of Le Rhône and formed the Société des Moteurs Gnome et Rhône. Developments of the 9C
continued to be their primary product, improving in power to about 110 hp (80 kW) in the 9J by the end of the war. The 9-series was the primary engine for most
early-war designs both in French and English service, as well as in Germany where, perhaps somewhat ironically, Oberursel had taken
out a license just before the war.
Post-WWI to WWII
With the end of WWI the company rapidly diversified, using their factories to produce chassis and engines for the Rolland-Pilain
and Piccard-Pictet cars, along with Ansaldo diesel engines, refrigerators, sewing machines and even jackhammers. In 1920 they also
introduced their first motorcycle, simply known as the Gnome et Rhône 500 cc. Various models were produced up to the early 1950s,
typically advertised as simply "Gnome Rhone" with no accents.
By 1920 their rotary engines were no longer competitive, and they had no new designs of their own. In 1921 they took out a
license to build the Bristol Jupiter, which was in the process of becoming the Gnome of its era. In 1922, Paul-Louis Weiller, a WWI
ace, took over the company and decided to focus it on aircraft engines once again. Their Jupiter designs, the 9A, were soon selling
very well. In 1926 they took out a license for the smaller 5-cylinder Bristol Titan, while Bristol licensed the Farman-style reduction
gearing used by Gnome.
Not satisfied to simply produce Bristol designs under license, Gnome started a major design effort based around the mechanicals
of the Titan. The results were introduced in 1927 as the K-series, spanning the 260 hp (190 kW) Gnome-Rhône 5K Titan, the 7-cylinder
370 hp (270 kW) version, the Gnome-Rhône 7K Titan Major, and the 9-cylinder 550 hp (405 kW) Gnome-Rhône 9K Mistral. All of these engines
were delivered in a variety of improved versions, named with a three letter code; the first letter was the series number (a through f
for instance), the second a r or l depending on which direction the engine turned, and the third indicating the charging system. With
the introduction of the K-series, Gnome ended royalty payments to Bristol. By 1930 they had delivered 6,000 Jupiters, Mistrals and
Titans, making them the largest engine company in France.
The 550 hp (405 kW) Mistral was no longer powerful enough for the rapidly-evolving industry of the time. To provide more power
Gnome once again turned to the two-row solution, using two banks of 7 cylinders, delivering the 625 hp (460 kW) Gnome-Rhône 14K
Mistral Major in 1929. The new engine was an instant hit. By 1933 the 14Kfrs had improved the power to 1,025 hp (750 kW) through
better supercharging (along with similar improvements in the Mistral, now at 770 hp or 570 kW), and the engine was once again being
licensed around the world.
Leaving the idea of having many engines in a single "K-series", Gnome continued work with the basic mechanical design to produce the
18-cylinder two-row Gnome-Rhône 18L of 1400 hp (1030 kW). Its power-to-weight ratio was not very good and work on the design was
eventually stopped in 1939. A smaller engine, the Gnome-Rhône 14M Mars was introduced to replace the earlier K-series Mistral, notable
primarily for its extremely compact frontal area, giving by far the most power for size of any engine of the era. It was especially
used in the Potez 631 aircraft family.
In 1936 the 14K-series was replaced by the Gnome-Rhône 14N delivering 1,100 hp (810 kW) from a slightly heavier engine that
nevertheless had a much better power-to-weight ratio. Starting with the N they introduced a new naming scheme, replacing the earlier
model letters with numbers, delivering the engine in versions that turned left with even numbers and right with odd. The original
14N-0/1 was run through a number of versions, the 14N-10/11 being used on the Bloch MB.210 bomber, the 14N-25 on early examples of
the MB.152 fighter, and the 14N-49 on late MB.152s as well as LeO 451s and Amiot 351s. The N-series finally ended with the 14N-50/51,
which delivered 1,210 hp (890 kW) for takeoff. The 14N was not as widely licensed, as the war was approaching and the French
government was becoming increasingly wary of licensing designs to potential enemies.
The 14N-series was itself replaced by the ultimate pre-war evolution of the line, the Gnome-Rhône 14R. The first versions
introduced in 1939, the 14R-4/5, produced 1,291 hp (950 kW) for takeoff and was only slightly heavier than the 14N. By 1940 the
improved 14R-8/9 was delivering 1,578 hp (1,161 kW) by increasing RPM from 2,400 to 2,600. Although this was a good figure for the
era, English and German design had already passed this mark, and would soon be pressing on 2,000 hp (1,500 kW).
With the fall of France in 1940, Gnome et Rhône was ordered to produce the BMW 801 under license, while the 14M saw limited use
on some German designs. The company became infamous for slow production, building only 8,500 engines by May 1944, when the Germans had
been estimating 25,000. That month a massive US air raid completely destroyed the original Gennevilliers factories.
With the end of the war, the company was in no condition to continue in the aero-engine business, although they picked up small
contracts to produce M4 Sherman tanks for the French army. In order to save what was left the company was nationalized on May 29,
1945, creating the Société Nationale d'Etude et de Construction de Moteurs d'Aviation (SNECMA), and producing the 14N, 14R and the
Licensed versions and developments
The 14K was one of the most popular engines of its era, widely licensed and used around the world. In Poland it was used for
export fighter variants, most notable PZL P.24. In particular it was used in Romania, where it powered a number of Polish designed PZL
fighters before finally becoming the main engine of the little-known but interesting IAR 80 fighter.
Isotta Fraschini and Piaggio of Italy both took out licenses, the former producing the K.14, the latter the P.XI. These were used
on a number of designs in the pre-war period, many of which were exported. This led to Manfred Weiss taking out a license in Hungary,
producing it as the WM K-14 in order to power their versions of the Reggiane Re.2000 fighter called the MAVAG Heja "Hawk", as well
as the Weiss WM 21 Sólyom.
One particularly important licensee was Nakajima, who produced it as the Sakae. The Sakae was one of the most popular Japanese
engines, powering the Mitsubishi Zero fighter as well as other designs.
The English firm Alvis had licensed the 14K and 18L, but neither entered production before the war ended. Nevertheless Alvis
pressed ahead with development, releasing the 9-cylinder Alvis 501 Leonides and later the 14-cylinder Alvis 701 Leonides Major. The
later saw some use on post-WWII helicopter designs.
The Soviet Union license-built both the 9A (as M-22) and the 14K (as M-85).
World War I
Le Rhône 9C
Le Rhône 9J - ( referred to widely as "the 110hp Le Rhône" )
Gnome 9N Monosoupape
Gnome-Rhône 9A Jupiter
Gnome-Rhône 5K Titan
Gnome-Rhône 7K Titan Major
Gnome-Rhône 9K Mistral
Gnome-Rhône 14K Mistral Major
World War II
Gnome-Rhône 14M Mars
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In 1898 a Spanish artillery captain, Emilio de la Cuadra, started with electric automobile production in Barcelona under the name of La Cuadra. In Paris, De la Cuadra met the Swiss engineer Marc Birkigt (1878 -1953), and hired him to work for the company in Spain. La Cuadra built their first gas powered engines from Birkigt designs. At some point in 1902 the company’s ownership changed hands to J. Castro and was renamed Fábrica Hispano-Suiza de Automóviles (Spanish-Swiss Car Factory), but this company also went bankrupt in December 1903.
The next reformation took place in 1904, creating La Hispano-Suiza Fábrica de Automóviles, also under Castro's direction. Four new engines were introduced in the next year and a half. A 3.8L engine and a 7.4L four cylinder engine were produced as well as a pair of bigger six cylinder power plants. This version of the company managed to avoid bankruptcy, and in Spain remained in operation, as a car, truck and aviation engine producer, with is main plant located in Barcelona, until 1946. The company mass-produced cars, trucks and buses (and a number of hand-built racing and luxury cars) some of which ended up being owned by King Alfonso XIII of Spain.
In the early years of the 20th century, France was proving to be a much larger market for the company’s luxury cars than Spain was. In 1911 a new factory, known as Hispano France, was set up in the Paris suburb of Levallois-Perret'. In 1914 they moved to larger factories at Bois-Colombes, and took the name Hispano-Suiza.
World War I Period
With the start of World War I the company turned to the creation of aircraft engines under the direction of Marc Birkigt. His solution to building aero engines was new, instead of machining separate steel cylinders and then screwing them to a crankcase, he used cast aluminium blocks into which thin steel liners were screwed. This made the engine much stiffer, easier to build, and lighter. His design was the first of what are today known as "cast block" engines, and he also incorporated overhead cams, propeller reduction gearing, and a host of other features that didn't appear on most other engines until the late 1920s.
Another major design detail, was the use of a hollow propeller shaft to allow a gun to be fired through the propeller spinner - thereby avoiding the need for a synchronizer gear. This design would be a feature of all Hispano-Suiza military engines to follow.
1918 - 1936 Period
After World War I, the company returned to automobile engine design, and in 1919 introduced the H6 engine, earning them an engineering reputation equal to that of Rolls-Royce in England. Through the 1920s and into the 1930s they built a series of luxury cars of increasing technical refinement and prestige.
The mascot statuette atop the radiator used by this firm after WWI, was the stork of the province of Alsace, taken from the squadron emblem painted on the side of the aircraft of the renowned WWI French ace (and Hispano-Suiza customer) Georges Guynemer, which was powered by an Hispano-Suiza engine
1937 - 1950 Period
In 1936 with the next war looming, Hispano-Suiza was told to stop production of cars and turn solely to aircraft engines once again. At the time they had just introduced a new series of water-cooled V12 engines, and the Hispano-Suiza 12Y was in huge demand for practically every French aircraft. However Hispano was never able to deliver enough of these engines to meet demand, and so many French fighters sat on the ground, complete but for the engine.
Another development of the era was a series of 20 mm auto cannon, first the Hispano-Suiza HS.9 and then the more famous Hispano-Suiza HS.404. The 404 was licensed for production in England and equipped almost all RAF fighter aircraft during the war. Production was also set up in the US, but these versions never matured even though the USAAC and US Navy both wanted to use it in place of their existing .50 weapons.
1950s - and on
After the Second World War Hispano-Suiza was primarily an aviation firm. Between 1945 and 1955 they built the Rolls-Royce Nene under license, began designing landing gear in 1950, and Martin-Baker ejection seats in 1955. Their attention turned increasingly to turbine manufacturing, and in 1968 they became a division of SNECMA. In 1999 they moved their turbine operations to a new factory in Bezons, using the original factories for power transmissions and accessory systems for jet engines. In 2005, SNECMA merged with SAGEM to form SAFRAN.