Category Archives: Through World War I


Breton Rotary Aircraft Engine

By William Pearce

On 25 February 1909, René Breton filed a French patent application for an internal combustion engine of a new configuration. For his design, Breton was awarded French patent 399,918 on 8 May 1909, and the patent was published on 10 July 1909. Breton was subsequently awarded British patent 4782 on 27 October 1910 and US patent 982,468 on 24 January 1911.


Sectional drawing from the Breton rotary engine patent. The three 160-degree Vee engine sections are visible, as are their crank disks. Planetary gears on the crank disk shafts meshed with a sun gear on the fixed central shaft and rotated the engine.

In his patent, Breton outlined a 12-cylinder, air-cooled, rotary aircraft engine designed to be compact and very light. The engine had a front and rear cylinder row, each with six cylinders. The cylinders of each row were arranged around the engine in three two-cylinder groups, with each two-cylinder group positioned 120 degrees around the center of the engine. Each two-cylinder group formed a 160-degree Vee twin. The front and rear rows were mirrored so that a front two-cylinder group matched with a rear two-cylinder group. Each front and rear cylinder was paired, fired simultaneously, and shared a common combustion chamber. The intake valve was on the rear side of the rear cylinder, and the exhaust valve was on the front side of the front cylinder.

The pistons of each two-cylinder, 160-degree Vee group were attached to a “crank disk” with fork-and-blade connecting rods. Each crank disk was built up from a shaft that ran on ball bearings and had a planet gear keyed at its center. The planet gear was sandwiched between the inner ends of front and rear disks, onto which the respective connecting rods were mounted. A front and rear outer disk closed out the basic assembly. The planet gears of the three crank disks engaged a sun gear mounted to a shaft at the center of the engine. Being a rotary engine, the central shaft was fixed to the airframe, and the engine rotated around the shaft. Each crank disk rotated four times for every revolution around the central shaft. With the propeller fixed to the front of the crankcase, the gearing meant that each four-stroke cylinder would fire twice before one revolution of the propeller/engine was completed.


Transverse drawing from the Breton rotary engine patent showing the connecting rods of a front and rear cylinder pair attached to the crank disk. At the center of the crank disk is the planetary gear.

Front and rear cam rings were mounted to the fixed central shaft to control the respective exhaust (front) and intake (rear) valves. The cam lobes on the cam ring actuated a lever that acted on a push rod to open the individual valves, each of which was held closed by a spring. The valve levers for the cylinder Vee groups were profiled, and the cam rings could slide on the central shaft. This combination allowed for certain Vee engine groups to be shut down by the cam rings sliding to achieve the desired interaction with the profiled valve levers. When an engine group was shut down, the intake valves were kept closed by the relocated intake cam ring missing the profiled intake lever, and the exhaust valves were kept open via a continuous collar on the relocated exhaust cam ring being in constant contact with the profiled exhaust lever. The cam rings would slide to positions in which they would operate either two, three, four, or six engine groups—respectively enabling either four, six, eight, or twelve cylinders.

As previously mentioned, the combustion chamber was shared by each front and rear cylinder pair. The combustion chamber was of a hemispherical design, but the cylinder head was of a “T” design with the underhead single intake valve and single exhaust valve on their respective sides of the cylinder pair. The patent drawings include a chamber at the rear of the engine that would distribute the air and fuel mixture from a carburetor to each cylinder pair via a manifold, but this induction system was not used on the prototype engine.


Another transverse drawing from the Breton rotary engine patent illustrating the common combustion chamber of the front and rear cylinder pair. The intake valve is on the left and the exhaust valve on the right. The fixed central shaft and its sun gear are at the center of the drawing. The cam rings are visible on the central shaft. At the bottom of the drawing is a crank disk with its two fans.

A centrifugal fan was mounted to each side of each disk crank assembly. A cover over the front side of each disk crank had a scoop that faced the direction of engine rotation and helped bring air into the fan. Air brought in would circulate through the crankcase and help cool engine’s internal components. The fan on the rear side of each crank disk would force the air out of the crankcase via an outlet that faced away from the direction of engine rotation. The patent proposes that some of the air warmed as it passed through the crankcase would be siphoned off to feed the induction chamber at the rear of the engine.

The prototype engine was very similar to what was described in the patent but differed mainly with the delivery of air and fuel into the cylinders. The internal fans no longer provided induction air, and there was no internal air chamber, carburetor, or intake manifolds. The prototype engine used fuel injection, with a pump for each cylinder pair controlled in a similar way as the valves. The fuel flowed through a line from the crankcase to each intake valve, and whatever injection pressure was present was amplified by the centrifugal action of the engine’s rotation. It appears air was drawn into the cylinder via openings in the intake valve housing.


The Breton Rotary as displayed at the 1909 Salon de l’aéronautique. Note the four-cylinder head casting and the individual fuel lines. The internal air-cooling exit covers can be seen over the crank disks.

Few details of the prototype engine have been found, but it appears to consist of an aluminum crankcase with steel cylinder barrels. The cooling fins on the cylinder barrels were angled to match the engine’s rotation and to keep the fins parallel to the airflow. With each engine section made up of a 160-degree Vee, the two end pairs of cylinders converged together at a 40-degree angle. A single cast metal head was used to cover the four converging cylinders. A single spark plug was positioned in the center of each cylinder pair. The spark plugs were fired from a magneto attached to the aircraft and powered by a ring gear mounted to the rear of the engine. The rear of the fixed central shaft extended from the engine to provide a mounting point to attach the engine to the airframe.

The Breton rotary engine had a 3.23 in (82 mm) bore and a 3.35 in (85 mm) stroke. Total displacement from its 12 cylinders was 329 cu in (5.39 L). The engine produced 60 hp (45 kW) at 400 rpm, which means the crank disks were each rotating at 1,600 rpm. Sources indicate that the engine produced 20 hp (15 kW) on four cylinders, 30 hp (22 KW) on six cylinders, and 40 hp (30 kW) on eight cylinders. Maximum engine speed was stated as 500 rpm (2,000 rpm for the crank disks). The relatively small engine weighed only 198 lb (90 kg).

The engine made its debut in October 1909 at the Salon de l’aéronautique in Paris and had a selling price of 10,000 Francs. The engine appeared again at the 1910 Salon and was modified with two magnetos in place of the single unit originally fitted. After 1910, no further information has been found regarding the engine or its testing. A photo exists showing the engine in a somewhat neglected state. It is possible that the prototype engine survived (at least into the 1960s) stored in a museum or private collection.


The Breton engine as seen at the 1910 Salon. This view illustrates the cylinder cooling fin angles to match the engine’s rotation. The engine appears very similar to the 1909 version with the exception of new dual magnetos.

– “Explosion-Motor” US patent 982,468 by René Breton (granted 24 January 1911)
– “Flight Engines at Paris Show” Flight (13 November 1909)
– “Aero Engines in the Paris Salon” The Aero (12 October 1909)
Les Moteurs a Pistons Aeronautiques Francais Tome II by Alfred Bodemer and Robert Laugier (1987)


Anzani 20-Cylinder Aircraft Engine

By William Pearce

Alessandro Ambrogio Anzani was born in Gorla, near Milan, Italy on 5 December 1877. As a young child, Anzani was exposed to the fundamentals of engineering and mechanical design by working at his uncle’s bicycle shop in Monza. In 1899, Anzani attended a bicycle race in Milan where he met and became friends with Frenchman Gabriel Poulain, the future cycling world champion. Poulain was impressed with Anzani’s mechanical aptitude and invited him to France.


Ads for the Anzani 20-cylinder engine first appeared in April 1913, and the ad above is from July 1913. The list price for the engine in 1914 was £1,072. (image via

Anzani moved to Saint-Nazaire, France in 1900, and with Poulain’s assistance, he competed in a few bicycle races. Anzani soon moved to Paris and was hired by Compagnie des Automobiles et Cycles Hurtu (Hurtu Automobile and Cycle Company). Hurtu originally manufactured sewing machines but was reorganized in 1899 to focus on the construction of automobiles and motorcycles. While at Hurtu, Anzani was exposed to the fine details of internal combustion engines, and he began racing motorcycles in 1903.

Anzani soon left Hurtu to focus on motorcycle racing. In 1905, Anzani became the first motorcycle world champion, a feat that was achieved on an Alcyon motorcycle powered by a Buchet engine that Anzani had prepared himself. In the 1905–1906 time period, Anzani was closely allied with the Buchet company, even working on and “piloting” their propeller-driven Aéro-motocyclette.


Rear view of the 20-cylinder engine shows its two magnetos. Note the bifurcated “Y” exhaust stacks and the rear carburetor under the engine.

Anzani’s motorcycle racing exploits had made him a rich man, and in December 1906, he founded La Société des Moteurs Anzani (The Anzani Motors Company) to manufacture motorcycle engines. The new company settled in Courbevoie, near Paris, France, and began manufacturing single and V-twin engines, which were similar to the respective Buchet types with which Anzani was previously involved. Around 1908, a three-cylinder engine was available. The three-cylinder engine was of a W or fan configuration; it had a center, vertical cylinder, and the two other cylinders were angled at 60 degrees.

Anzani engines quickly established themselves to be light and reliable. Such engines caught the attention of early aviation pioneers, who desperately sought such power plants. One of the first to order an Anzani engine to power an aircraft was Louis Blériot, who used the three-cylinder, 45 hp (34 kW) engine to make the first crossing of the English Channel by air on 25 July 1909. After Blériot’s success, Anzani received numerous orders for engines to power aircraft, which resulted in the company redirecting its focus from motorcycle engines to aircraft engines. In late 1909, La Société des Moteurs Anzani was reorganized as Anzani Moteurs d’Aviation (Anzani Aviation Engines).


Frank Coffyn with the Azani 20-cylinder engine purchased by Robert Collier to power his Burgess Company Model L Flying Boat. Note the front carburetor under the engine and the induction pipes leading from the front crankcase chamber to the cylinders.

The Anzani company quickly went to work creating a large line of aircraft engines. In addition to the previously offered V-twin and three-cylinder fan engines, single-row three-, five-, and seven-cylinder radials were built. In the never-ending search for more power, the new single-row engines were used as a basis for two-row engines with six, ten, and 14 cylinders. In 1912, the two-row, 10-cylinder engine was used to develop a four-row, 20-cylinder radial, one of the most powerful engines of the time.

The Anzani 20-cyinder air-cooled radial was constructed in a similar fashion as other Anzani engines. The direct-drive engine consisted of four rows of five cylinders. However, the front two rows and the rear two rows were essentially paired together. The engine appeared more as a two-row radial with 10 cylinders in each row. The cylinders of a single row were separated by 72 degrees, paired rows were separated by 36 degrees, and all cylinders were separated by 18 degrees.


Coffyn stands in the Model L Flying Boat with the 20-cylinder engine mounted between the biplane’s wings. It appears the engine’s installation allowed for unrestricted access to cooling air.

The engine had an aluminum crankcase made in three parts. The central casting comprised the power section with four rows of five cylinders. The front and rear castings acted as covers and were secured to the central casting via studs. They also supported the respective ends of the crankshaft via roller bearings pressed into their castings. The rear casting also supported the accessory drives for the two magnetos. The hollow, two-throw crankshaft did not have a center support. The connecting rods for the front and rear cylinder row pairs were placed side-by-side on a common crankpin and used slipper-type bearings. The two crankshaft throws had an included angle of 162 degrees.

Under the engine, two carburetors were mounted—one toward the front and one toward the rear. Air was drawn through the carburetors and into separate chambers in the crankcase that fed the front and rear cylinder-row pairs. The air and fuel mixture was delivered from the chambers to the individual cylinders via a vertical pipe that ran along the outside of each cylinder. A single automatic (atmospheric) intake valve admitted the air and fuel mixture into the cylinder. The incoming charge was ignited by a single spark plug, and the exhaust was expelled via a short bifurcated exhaust stack. Each exhaust valve was operated via a rocker arm and push rod. The push rods were actuated via roller tappets from a cam ring. A cam ring at the front of the engine controlled the exhaust valves for the front pair of cylinder rows, and a cam ring at the rear of the engine controlled the exhaust valves for the rear pair of cylinder rows. Each cam ring had four lobes and ran at .25 crankshaft speed.


Right-rear view of the Model L provides a good view of the 20-cylinder engine in the pusher configuration. Note the extension shaft leading to the wooden four-blade propeller (made up of two two-blade units) that was 8 ft 4 in (2.54 m) in diameter.

Each of the cylinders was secured to the crankcase via two long lugs that passed through the crankcase to the cylinder head. The cylinders were made of cast iron with an integral cylinder head and cooling fins. The engine’s flat top pistons were made from cast iron. Each of the two magnetos attached to the rear of the engine fired half of the cylinders, with one magneto firing the left cylinders and the other firing the right cylinders.

The Anzani 20-cyinder air-cooled radial had a 4.13 in (105 mm) bore and a 5.51 in (140 mm) stroke. The engine’s total displacement was 1,480 cu in (21.25 L), and it produced 200 hp (149 kW) at 1,250 rpm. The 20-cylinder engine weighed 682 lb (309 kg).

The 20-cylinder engine was completed and tested by early 1913. For testing, the engine was secured in what resembled an aircraft’s frame complete with wheels and run stationary on the ground. One of the first (perhaps the first) engines was purchased by Robert Joseph Collier for use in a Burgess Company Model L Flying Boat that Collier was having built. Collier created the Collier Trophy that was first awarded in 1911 and continues to be awarded today “for the greatest achievement in aeronautics or astronautics in America, with respect to improving the performance, efficiency, and safety of air or space vehicles, the value of which has been thoroughly demonstrated by actual use during the preceding year.” The Burgess Company (or the Burgess Company and Curtis, Inc) was founded by William Starling Burgess and Greely S. Curtis at Marblehead, Massachusetts in 1910.


Robert Collier piloting the Model L over Lower New York Bay in late 1913.

The Anzani 20-cylinder engine was shipped to the United States in mid-1913 and installed in the Model L. The Model L Flying Boat was a pusher biplane that had a 41 ft 4 in (12.60 m) wingspan, was 30 ft 6 in (9.30 m) long, and had gross weight of 2,050 lb (930 kg). The aircraft’s top speed was around 75 mph (121 km/h). The Anzani engine was installed between the aircraft’s wings, and it turned a four-blade, 8 ft 4 in (2.54 m) diameter propeller via an extension shaft. The Model L made its first flight on 19 July 1913 piloted by Frank Coffyn.

Another 20-cylinder engine was part of the Anzani display at the Salon de l’Aéronautique in Paris in December 1913. Other Anzani engines displayed were the 3-, 5-, 7-, 10-, and 14-cylinder radials. The 20-cylinder engine was offered through 1915, but it seems that not many were sold. Involvement in World War I might have ended whatever limited production run the engine had. No aircraft beyond the Burgess Model L are known to have flown with the Anzani 20-cyliner. The engine in Collier’s Model L was removed during World War I and eventually given to the West Side YMCA in New York, New York around 1919 where it was used as an instructional aid.


The 20-cylinder engine in the possession of the West Side YMCA in New York circa 1919. The engine was used as an instructional aid, but it is not known what ultimately happened to the 20-cylinder engine. Note the engine’s mounting ring which could be used in tractor or pusher installations.

1914 Types Anzani Engines (1914)
A History of Aeronautics by E. Charles Vivian (1921)
Aerosphere 1939 by Glenn D. Angle (1939)
Les moteurs Anzani by Gérard Hartmann (22 February 2007)
– “Anzani Engines and the new 200 HP Model,” Flight (5 July 1913)
– “Aero Engines at the Paris Show, 1913” Flight (24 January 1914)

daimler-mercedes d vi back

Daimler-Mercedes D VI W-18 Aircraft Engine

By William Pearce

By 1915, the Germans had begun to experiment with very large aircraft known as Riesenflugzeug (giant aircraft). These aircraft had been developed from the G-class bombers and are often referred to as R-planes. In 1916, the potential of such an aircraft to carry heavy bombloads into enemy territory was recognized, and the deficiencies of airships that had been developed to serve in that same role was apparent. Efforts were undertaken to increase R-plane production and withdraw airships from long-range bomber missions.

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The preserved Daimler-Mercedes D VI W-18 engine. The individual cylinders on each bank were linked by a common overhead camshaft housing. Note the water-jacketed copper intake manifolds. (Evžen Všetečka image via

To promote the development of larger and more capable R-planes, larger and more powerful aircraft engines were needed. As early as 1915, the Idflieg (Inspektion der Fliegertruppen or Inspectorate of Flying Troops) had encouraged various German engine manufacturers to develop large aircraft engines capable of 500 hp (375 kW). These engines were known as Class VI engines and would be used to power R-planes. Daimler Motoren Gesellschaft (Daimler) was one of the companies that worked to build a large Class VI aircraft engine.

Daimler’s design was known as the D VI, but it is also referred to as the Mercedes D VI or Daimler-Mercedes D VI. Daimler often used the Mercedes name for many of its products. The D VI engine utilized the basic cylinder from the 180 hp (134 kW) Daimler-Mercedes D IIIa engine and incorporated features from the 260 hp (194 kW) D IVa engine. Both of those engines were six-cylinder inlines. However, the D VI had three rows of six-cylinders, creating a W-18 engine. The center cylinder row was vertical, and the left and right rows were angled 40 degrees from the center row.

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Front view of the D VI illustrates the water pump mounted directly in front of the center cylinder bank. Note the direct drive crankshaft. (Evžen Všetečka image via

The D VI engine used individual steel cylinders with one intake and one exhaust valve. The valves of each cylinder row were actuated by a single overhead camshaft driven from the rear of the engine via a vertical shaft. The camshaft acted upon rocker arms that protruded from the camshaft housing above each cylinder to the exposed cylinder valves. A water jacket made of pressed steel was welded to the cylinder. Each piston was made of a forged-steel head screwed and welded onto a cast iron skirt. The cylinder’s compression ratio was 4.7 to 1.

Each cylinder was attached to the two-piece steel crankcase via four studs. Most likely, the studs for the center cylinder row extended into the bottom half of the crankcase and helped secure the two crankcase halves. The crankshaft was supported by seven main bearings and was connected directly to the propeller. A water pump was driven by the crankshaft at the front of the engine. At the rear of the engine, a vertical shaft extending from the crankshaft drove a magneto for each cylinder bank and an oil pump. Each of the cylinders had two spark plugs.

Induction air was drawn into an air chamber inside the crankcase where it was warmed. The air then passed through two water-jacketed pipes cast integral with the lower crankcase half at the rear of the engine. The two pipes split into three inline carburetors, each feeding one cylinder bank via an intake manifold. The intake manifold was made of copper and was water-jacketed. The left cylinder bank had its intake manifold positioned on the right side. The center and right cylinder banks had their intake manifolds positioned on the left side. The exhaust was expelled from each cylinder via an individual stack on the side opposite the intake.

daimler-mercedes d vi back

Rear view of the D VI shows the engine’s induction stemming from the lower crankcase housing and feeding into the three carburetors.

The D VI had a 5.51 in (140 mm) bore and a 6.30 in (160 mm) stroke. The engine’s total displacement was 2,705 cu in (44.3 L). The D VI produced 513 hp (382 kW) at 1,440 rpm for takeoff and had a maximum continuous output of 493 hp (368 kW) at 1,400 rpm. Specific fuel consumption was .477 lb/hp/hr (290 g/kW/h). The engine weighed 1,636 lb (742 kg).

The Daimler D VI engine was first run in 1916. However, development of the D IIIa and D IVa engines took priority, causing the D VI to lag behind. The D VI passed a certification test in December 1918, but World War I was over by that time, and such and engine was no longer needed. Military restrictions imposed on Germany by the Treaty of Versailles most likely influenced the abandonment of the D VI engine, and no further work was undertaken.

The sole surviving D VI engine has been preserved and is on display at the Flugausstellung L.+ P. Junior museum in Hermeskeil, Germany.

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The D VI engine had mounts cast integral with the upper crankcase, but the engine was never installed in any aircraft. Note the pedestal pads onto which the cylinders were mounted. (Evžen Všetečka image via

Flugmotoren und Strahltriebwerke by Kyrill von Gersdorff, et. al. (2007)
Report on the 180 H.P. Mercedes Aero Engine by the Ministry of Munitions Technical Department, Aircraft Production (March 1918)
Report on the 260-H.P. Mercedes Aero Engine by the Technical Information Section of the Air Board (July 1917)

Thomas X-8 engine

Thomas / Leyland X-8 Aircraft Engine

By William Pearce

John Godfrey Parry Thomas was a British engineer and was widely known as Parry Thomas. During World War I, Thomas was a member of the Munitions Invention Board and was brought on as the chief engineer at Leyland Motors in 1917 to help the firm develop an aircraft engine.

Allan Ferguson had been working at Leyland on the design of the aircraft engine. The engine Ferguson had designed was a 450 hp (336 kW), water-cooled W-18 with banks set at 40 degrees. Each bank consisted of two three-cylinder blocks, and there were plans to make a W-9 engine with just three banks of three cylinders. Long pushrods extended from camshafts in the crankcase between the cylinder banks to the top of the cylinders to actuate the overhead valves. Thomas felt that the W-18 engine would not be successful and proposed his own design, which won the approval of Leyland management.

Thomas X-8 engine

The Thomas (Leyland) X-8 engine was made from aluminum and had many interesting features. At the rear of the engine, the handle is attached to a dynamo for starting. Just above the dynamo is the crankshaft-driven water pump. The engine’s carburetors are mounted on either side of the water pump. Note the integral passageways leading from the carburetor to the cylinders. The oil sump tank is positioned in the lower engine Vee.

Assisted by Fred Sumner and Reid Railton, Thomas’ engine design was an X-8 with cylinder banks spaced at 90 degrees. Each cylinder bank consisted of two paired cylinders. The cylinder banks were cast integral with the aluminum crankcase, and nickel-chrome cylinder wet liners were heat-shrunk into the cylinder banks. An aluminum cylinder head was attached to each cylinder bank via eight bolts. A propeller gear reduction was incorporated into the engine. The gear reduction used bevel gears and reduced the propeller speed to .50 times crankshaft speed. The gear reduction kept the propeller position in line with the crankshaft.

A single overhead camshaft operated the two intake and two exhaust valves for each cylinder. The camshaft was driven via a vertical shaft at the rear of the engine. The valves were closed by leaf springs. Via adjustable screws, one end of a leaf spring was attached to an intake valve while the other end of the spring was attached to an exhaust valve. The springs were allowed to articulate at their mounting point so that as one valve was opened, additional tension was applied to the closed valve for an even tighter seal.

Two carburetors were positioned at the rear of the engine, with each carburetor providing the air/fuel mixture for one side of the engine. Each carburetor was mounted to an integral intake passageway in the crankcase, with four individual ducts branching off from the passageway. Each duct connected one cylinder to the intake passageway. Exhaust was expelled from the upper and lower engine Vees. Each cylinder had two spark plugs fired by either a magneto or battery ignition.

A water pump driven at the rear of the engine by the crankshaft circulated water through the engine at around 48 gpm (182 L). The coolant flowed into the cylinder banks and around the exhaust ports to keep the exhaust valves cool. A pipe system enabled water to flow through the hollow crankshaft at 10 gpm (36 L), cooling the three main bearings and two connecting rod bearings. The water also cooled the oil that flowed through the crankshaft and to the bearings. To further cool the oil, the water and oil flowed into the propeller gear reduction, where the oil passed along the finned outer side of the water-cooled propeller shaft.

Thomas leaf spring valves

While not of the X-8 engine, this drawing does depict the leaf spring valves, similar to the setup used in the X-8 engine. The leaf spring (5) held the valves (3 and 4) closed. Lobes (11) on the camshaft (12) acted on the rockers (9 and 10) to open the valves. The leaf spring mount (8) could move up and down to add tension on the closed valve for a tighter seal. (GB patent 216,607, granted 5 June 1924)

Attached to each of the crankshaft’s two crankpins was a master connecting rod, and three articulated rods were attached to each master rod. The crankshaft had both of its crankpins inline, which meant that the pistons for one cylinder bank would both be at top dead center at the same time. One source states that the crankpins were in the same phase, meaning the two cylinders of the same bank would be on the same stroke, essentially making the X-8 engine operate like two synchronized X-4 engines. This was reportedly done to prevent any rocking motion created by the front X-4 firing followed by a rear X-4-cylinder firing 90 degrees later. However, a different source says the cylinders were phased 360 degrees apart, which would make more sense. While the pistons of one cylinder bank were both at top dead center, one cylinder was starting the intake stroke while the other was starting the power stroke. The 360-degree phasing would create a rather smooth firing order, such as bank 1 front cylinder (1F), bank 2 rear cylinder (2R), 3F, 4R, 1R, 2F, 3R, and 4F. However, the engine’s true firing order is not known.

A dry-sump lubrication system was used. Oil from the engine was collected in a one gallon (4.5 L) tank mounted in the lower engine Vee. The oil was then returned to a main oil tank of approximately eight gallons (32 L) installed in the aircraft. For starting, the X-8 engine used an electric starter motor or a hand-cranked dynamo. The engine incorporated an interrupter gear for firing guns through the propeller arc.

The X-8 engine had a 6.0 in (152 mm) bore and a 4.5 in (114 mm) stroke. The engine displaced 1,018 cu in (16.7 L) and produced 300 hp (224 kW) at 2,500 rpm and 10,000 ft (3,048 m). Maximum engine speed was around 3,500 rpm. The X-8 engine weighed around 500 lb (227 kg). For the time, 500 lb (227 kg) was remarkably light for a 300 hp (224 kW) engine. The X-8 was noted as being very compact, but a list of engine dimensions has not been found.

Thomas X-8 drawing

Patent drawing of the X-8’s crankshaft with its inline crankpins. The water pump (4) housed the crankshaft-driven impeller (9). Water was pumped through an inlet (11), through a passageway (10), and into the pipe built-up in the hollow crankshaft. The water then flowed through the propeller shaft (36) to cool oil in an adjacent passageway (45).

The design of the Thomas X-8 was completed in December 1917 and submitted to the Air Ministry. Thomas initiated an extensive part-testing program that resulted in the creation of numerous test fixtures. In conjunction with the test-fixtures, A single-cylinder test engine was built and tested in 1918. The single-cylinder produced 37 hp (28 kW) at 2,500 rpm and 53 hp (40 kW) at 3,700 rpm. These outputs equated to 296 hp (221 kW) and 424 hp (316 kW) respectively for the complete eight-cylinder engine. However, the piston in the single-cylinder engine failed after five minutes of running between 3,500 and 3,700 rpm.

A complete X-8 engine was built and run for the first time in August 1918. Compression ratios of 5.8 and 6.3 were used on the single-cylinder engine, but the compression ratio of the complete engine has not been found. Reportedly, the engine was hastily assembled because government inspectors wanted the test two weeks earlier than planned. The X-8 engine’s lightly-built crankcase deformed and closed in the crankshaft bearing clearance, resulting in the engine seizing after a few hours of running.

With the end of World War I on 11 November 1918, further work on the Thomas X-8 engine was abandoned. A number of features from the aircraft engine were later used on the Leyland automotive straight-eight engine developed in 1920. Thomas went on to become a legend at the Brooklands Raceway, campaign one of the first aero-engined Land Speed Record (LSR) monster cars, and set a flying-mile (1.6 km) LSR of 170.624 mph (274.593 km/h) on 28 April 1926. Thomas tragically died in a crash attempting another LSR on 3 March 1927. His death marked the first time a driver was killed while in direct pursuit of a LSR.

Parry Thomas at Brooklands Getty

Thomas behind the wheel of his Leyland-Thomas racer at Brooklands on 4 October 1926. (Getty image)

– “AIR: Parry Thomas’s Aero-Engine” by William Boddy, Motor Sport (February 1995)
– “The Life Story of Parry-Thomas” by Fred Sumner, Motor Sport (November 1941)
– “Internal Combustion Engine,” US patent 1,346,280 by John Godfrey Parry Thomas (granted 13 July 1920)
Reid Railton: Man of Speed by Karl Ludvigsen (2018)
Parry Thomas by Hugh Tours (1959)


Dutheil-Chalmers Éole Opposed-Piston Aircraft Engine

By William Pearce

In 1906, the French company Société L. Dutheil, R. Chalmers et Cie (Dutheil-Chalmers) began developing aircraft engines for early aviation pioneers. The company was headquartered in Seine, France and was founded by Louis Dutheil and Robert-Arthur Chalmers. Although most of their engines were water cooled, the Dutheil-Chalmers’ horizontal aviation engines may have been the first successful versions of the horizontal type that is now used ubiquitously in light aircraft. Continuing to innovate for the new field of aviation, Dutheil-Chalmers soon developed a line of horizontal, opposed-piston engines.

Dutheil Chalmers Eole patent

Taken from the Dutheil-Chalmers British patent of 1909, this drawing shows the layout of the horizontal, opposed-piston engine. The dashed lines represent the bevel-gear cross shaft that synchronized the two crankshafts.

On 23 November 1908, Dutheil-Chalmers applied for a French patent 396,613 that outlined their concept of an opposed-piston engine, as well as other engine types. The French patent is referenced in British patent 26,549, which was applied for on 16 November 1909 and granted on 21 July 1910. In the British patent, Dutheil-Chalmers stated that the engine would have two crankshafts. The output shaft would not be a power shaft that connected the two crankshafts. Rather, the crankshafts would rotate in opposite directions (counter-rotating), and a propeller would mount directly to each crankshaft. This is the same power transfer method used in the SPA-Faccioli opposed-piston aircraft engines. While the Dutheil-Chalmers and SPA-Faccioli engines shared a similar concept and were built and developed at the same time, there is no indication that either company copied the other.

The Dutheil-Chalmers opposed-piston engines are sometimes referred to as Éole engines. It is not clear if Dutheil-Chalmers marketed the engines for a time under a different name or if Éole was just the name they gave to their line of opposed-piston engines. Éole is the French name for Aeolus, the ruler of the winds in Greek mythology. The engines were primarily intended to power airships. The two counter-rotating propellers would cancel out the torque associated with a single propeller on a standard engine. In addition, the opposed-piston engine’s two-propeller design did not require the heavy and cumbersome shafting and gears necessary for a conventional single-crankshaft engine to power two propellers.

Dutheil Chalmers Eole 2 view

Top and side view drawings of the four-cylinder, opposed-piston engine. The drawings show no valve train and differ slightly from photos of the actual engine, but they give an idea of the engine’s general layout.

Four different horizontal, opposed-piston engine sizes were announced, all of which were water-cooled. Three of the engines had the same bore and stroke but differed in the number of cylinders used. These engines had two, three, and four cylinders. Each had a 4.33 in (110 mm) bore and a 5.91 in (150 mm) stroke, which was an 11.81 in (300 mm) stroke equivalent with the two pistons per cylinder. The two-cylinder engine displaced 348 cu in (5.7 L) and produced 38 hp (28 kW) at 1,000 rpm. The engine weighed 220 lb (100 kg). The three-cylinder engine displaced 522 cu in (8.6 L) and produced 56 hp (42 kW) at 1,000 rpm. The engine weighed 397 lb (180 kg). The four-cylinder engine displaced 696 cu in (11.4 L) and produced 75 hp (56 kW) at 1,000 rpm. The engine weighed 529 lb (240 kg). It is not clear if any of these engines were built.

The fourth engine was built, and it was the largest opposed-piston engine in the Dutheil-Chalmers line. The bore was enlarged to 4.92 in (125 mm), and the stroke remained the same at 5.91 in (150 mm)—an 11.81 in (300 mm) equivalent with the two pistons per cylinder. The four-cylinder engine displaced 899 cu in (14.7 L) and produced 97 hp (72 kW) at 1,000 rpm. Often, the engine is listed as producing 100 hp (75 kW). The four-cylinder engine weighed 794 lb (360 kg).

Dutheil Chalmers Eole front

This Drawing illustrates the front of the Dutheil-Chalmers opposed-piston engine. Note the cross shaft that synchronized the two crankshafts. The gear on the cross shaft drove the engine’s camshaft. The pushrods, rockers, and valves are visible.

Only the 97 hp (72 kW) engine was exhibited, but it was not seen until 1910. The engine was displayed at the Paris Flight Salon, which occurred in October 1910. The engine consisted of four individual cylinders made from cast iron. The horizontal cylinders were attached to crankcases on the left and right. Threaded rods secured the crankcases together and squeezed the cylinders between the crankcases. Each crankcase housed a crankshaft, and the two crankshafts were synchronized by a bevel-gear cross shaft positioned at the front of the engine. A two-blade propeller was attached to each crankshaft. The propellers were phased so that when one was in the horizontal position, the other was in the vertical position.

Near the center of the cross shaft was a gear that drove the camshaft, which was positioned under the engine. The camshaft actuated pushrods for the intake valves on the lower side of the engine and the exhaust valves on the upper side of the engine. The pushrods of the intake valves travel between the cylinders. All of the pushrods acted on rocker arms that actuated the valves positioned in the middle of the cylinder. Each cylinder had one intake and one exhaust valve.

No information has been found that indicates any Dutheil-Chalmers Éole opposed-piston engines were used in any airship or aircraft. Still, it is an unusual engine conceived and built at a time of great innovation, not just in aviation, but in all technical fields.


The 97 hp (72 kW), four-cylinder, eight-piston engine on display at the Paris Flight Salon in 1910. The engine has appeared in various publications as both a Dutheil-Chalmers and an Éole. Note the rods that secured the crankcases together. What appears to be the camshaft can be seen under the engine. (alternate view)

Les Moteurs a Pistons Aeronautiques Francais Tome II by Alfred Bodemer and Robert Laugier (1987)
– “Improvements in or connected with Motors especially applicable to Aviation and Aerostation Purposes” GB patent 26,549 by L. Dutheil, R. Chalmers and Company (granted 21 July 1910)
– “Motors for Aerial Navigation—V” by J. S. Critchley, The Horseless Age (26 October 1910)
– “Aerial Motors at the Salon” by Oiseau, Flight (5 November 1910)

SPA-Faccioli N3 rear

SPA-Faccioli Opposed-Piston Aircraft Engines

By William Pearce

Aristide Faccioli was an Italian engineer. In the late 1800s, he became fascinated with aviation and worked to unravel the mysteries of powered flight. With little progress in aviation, Aristide had turned to automobile development by 1898. He worked for Ceirano GB & C and designed Italy’s first automobile, the Welleyes. Ceirano GB & C did not have the finances to produce the automobile, so a new company was established for automobile production. This company was called Fabbrica Italiana Automobili Torino or FIAT, and it bought the rights, plans, and patents for the Welleyes. The Welleyes became FIAT’s first production automobile, the 3 ½ CV.

SPA-Faccioli N1

The SPA-Faccioli N.1 engine with its four cylinders, each housing two opposed pistons. At the rear of the engine (bottom of image) is the cross shaft linking the two crankshafts. Note the gear on the cross shaft that drove the camshaft.

Aristide became FIAT’s first technical director, but he left in 1901 to start his own automobile company. In 1905, Aristide moved from automobile production to engine design. However, Aristide’s focus returned to aviation once he learned of the successful flights of the Wright Brothers and other early pioneers. In 1907, Aristide shut down his companies and worked on aircraft and aircraft engine designs. In 1908, Aristide visited a close friend, Matteo Ceirano, seeking financial support. Matteo was one of Ceirano GB & C’s founders and was a co-founder of SPA (Società Ligure Piemontese Automobili). Matteo and SPA backed Aristide and encouraged him to continue his aeronautical work.

Aristide’s first engine was the SPA-Faccioli N.1. The N.1 was a water-cooled, horizontal, opposed-piston engine. Each side of the engine had a crankshaft that drove pistons in the engine’s four, individual cylinders. Attached to each crankshaft was a propeller. The crankshafts and their propellers turned in opposite directions (counter-rotating). When viewed from the rear of the engine, the right propeller turned clockwise, and the left propeller turned counterclockwise. The two-blade, wooden propellers were phased so that when one was horizontal the other was vertical. The dual, counter-rotating propeller design was an effort to eliminate engine vibrations and cancel out propeller torque.

SPA-Faccioli N2

This rear view of the SPA-Faccioli N.2 illustrates that the engine was much more refined than the N.1. Note the magneto driven above the cross shaft and the gear train driven below.

The two crankshafts were synchronized by a bevel-gear cross shaft that ran along the rear of the engine. Geared to the cross shaft was a camshaft that ran under the engine. The camshaft actuated the intake and exhaust valves that were located in the middle of each cylinder. As the two pistons in each cylinder came together, the air/fuel mixture was compressed. Once the mixture was ignited by the spark plug in the middle of the cylinder, the expanding gases pushed the pistons back, operating like any other four-stroke engine. The N.1 had a 4.41 in (112 mm) bore and a 5.91 in (150 mm) stroke. The two pistons per cylinder effectively gave the N.1 an 11.81 in (300 mm) stroke. The engine displaced 721 cu in (11.82 L) and produced 80 hp (60 kW) at 1,200 rpm. The N.1 weighed 529 lb (240 kg).

The N.1 engine was installed in the Faccioli N.1 aircraft, which was a triplane pusher design. Flown by Mario Faccioli, Aristide’s son, the engine, aircraft, and pilot all made their first flight on 13 January 1909. The aircraft quickly got away from Mario, and the subsequent crash injured Mario and destroyed the aircraft. Although brief, the flight marked the first time an Italian-designed and built aircraft was flown with an Italian-designed and built engine. With all parties undeterred, the N.1 engine was installed in the Faccioli N.2 aircraft (a biplane pusher with a front-mounted elevator) and flown by Mario in June 1909. After a few flights, Mario and the N.2 aircraft were involved in an accident that again injured Mario and destroyed the aircraft.

Faccioli N3 aircraft

Mario Faccioli sits on the Faccioli N.3 aircraft in 1910. Note the covers over the N.2 engine’s cross shaft bevel gears. Since the propellers rotated in opposite directions, when one was vertical, the other was horizontal.

After these setbacks, Aristide designed a new engine, the SPA-Faccioli N.2. The N.2 had many features in common with the N.1: water-cooling, opposed-pistons, dual crankshafts, a bevel-gear cross shaft, and counter-rotating propellers. However, the N.2 was a single cylinder engine. The engine’s magneto was driven from the cross shaft. The N.2’s intake was positioned on the bottom side of the engine, and exhaust was expelled from the top side. The N.2 had a 3.94 in (100 mm) bore and a 5.12 in (130 mm) stroke—a 10.24 in (260 mm) equivalent for the two pistons per cylinder. The engine displaced 249 cu in (4.08 L) and produced 20 hp (15 kW) at 1,200 rpm and 25 hp (19 kW) at 1,500 rpm. The N.2 weighed 106 lb (48 kg).

The N.2 engine was installed in the Faccioli N.3 aircraft. With a very similar layout to the N.2 aircraft, the N.3 pusher biplane was smaller and did not have the front-mounted elevator. Mario was again the test pilot, and he first flew the aircraft on 12 February 1910. Many flights were made throughout February and March. On 26 March 1910, one propeller came off the engine and damaged the aircraft while it was in flight. Mario was injured in the subsequent crash, and the N.3 aircraft was damaged. Aircraft and pilot flew again in the summer, but Aristide was already working on a new aircraft design.

SPA-Faccioli N3 rear

This rear view of the SPA-Faccioli N.3 shows many features common with the N.2 engine. However, note the 20 degree cylinder angle extending from the crankshafts. The camshaft was driven from the cross shaft and extended through the engine. Two pushrods extend from both the top and bottom of the camshaft. The black plugs in the center of the cylinders cover ports for spark plugs. (W. R. Pearce image)

The N.2 engine was installed in the Faccioli N.4 aircraft, a further refinement of the Faccioli line. The aircraft was first flown by Mario in July 1910. On 15 October 1910, Mario used the N.4 aircraft to get his Italian pilot’s license (No. 21). This was the first time an Italian-designed and built aircraft was used to obtain a pilot’s license.

For his next aircraft, the Faccioli N.5, Aristide needed more power. The new SPA-Faccioli N.3 engine was built upon knowledge gained from the previous engines. Again, the engine was water-cooled with opposed-pistons and had dual crankshafts (synched by a bevel-gear cross shaft) that drove counter-rotating propellers. However, the cylinder arrangement of the N.3 was unique. In essence, the N.3 was made up of two V-4 engines mounted horizontally and attached together via their combustion chambers. The cylinders of the complete engine formed a diamond shape, with the cylinders angled at 20 degrees relative to the crankshaft. This gave the cylinders a 160 degree bend at their middle. Technically, the pistons no longer shared a common cylinder, but the cylinders did still share a combustion chamber. Some sources define the N.3 as a four-cylinder opposed-piston engine, and other sources define it as an eight-cylinder engine in which opposed pairs of cylinders shared a common combustion chamber.

SPA-Faccioli N3 front

The N.3 engine’s intake manifold can be seen on the left side of the image; the exhaust ports are also visible to the right of the valves. Note the camshaft extending through the engine, and the pushrods that actuated the valves. The front side of the engine still has its two spark plugs.

Two magnetos were driven from the cross shaft at the rear of the N.3 engine. The magnetos fired one spark plug per cylinder pair. The spark plugs were positioned either on the front of the engine or on the back, depending on the cylinder. The cross shaft also drove a short camshaft that extended through the diamond between the cylinders. Via pushrods and rocker arms, the camshaft actuated the one intake and one exhaust valve for each cylinder pair. An intake manifold mounted to the front of the engine brought air and fuel into the right side of the engine, and the exhaust was expelled from the left side of the engine. The N.3 had a 2.95 in (75 mm) bore and a 5.91 in (150 mm) stroke. The engine displaced 324 cu in (5.30 L) and produced 40 hp (30 kW) at 1,200 rpm and 50 hp (37 kW) at 1,600 rpm. The N.3 weighed 198 lb (90 kg).

The N.3 engine was finished in early 1911, but the Faccioli N.5 aircraft was not. The N.3 engine was installed in the N.4 aircraft, and Mario continued his role as chief pilot. The N.3-powered N.4 aircraft was entered in various competitions during the Settimana Aerea Torinese (Turinese Air Week) held in June 1911. On 25 June 1911, the last day of the competition, a mechanical failure on the aircraft caused Mario and the N.4 to crash. As with previous crashes, Mario was injured, and the aircraft was destroyed.

Faccioli N4 aircraft

The Faccioli N.4 aircraft was originally powered by the SPA-Faccioli N.2 engine. In 1911, the eight-cylinder SPA-Faccioli N.3 engine was installed. This image was taken in June 1911, with the N.3 engine installed and Mario in the aircraft.

It is not clear if the Faccioli N.5 aircraft was ever completed. Aristide’s involvement in aviation seemed to wane after the crash of the N.4 aircraft. In fact, the last SPA-Faccioli engine may have been a development of the N.3 undertaken exclusively by SPA without much involvement from Faccioli.

Built in late 1911 or early 1912, the SPA-Faccioli N.4 engine was an enlarged and refined N.3. With the N.4, eight cylinders were again positioned in a diamond configuration, angled at 20 degrees at the crankshafts and 160 degrees at the combustion chambers. Each opposed cylinder pair shared a common combustion chamber. Each cylinder pair now had two spark plugs, and they were fired by two magnetos, one driven directly from the rear of each crankshaft. The cross shaft synchronizing the crankshafts also served as the camshaft. At the rear of the engine, the cross shaft drove pushrods that acted on rocker arms mounted to the top and bottom of the engine. The rocker arms actuated the one intake and one exhaust valve per cylinder pair, positioned at the center of the cylinders. The intake manifold was positioned behind the engine, to the left of center. The manifold fed the air/fuel mixture to a passageway in the cylinder casting that ran on the left side of the valves. The exhaust was expelled to the right of the valves.

SPA-Faccioli N4 front

The SPA-Faccioli N.4 was the final refinement of the Faccioli engine line. The magnetos can be seen behind the engine; each was driven from the rear of a crankshaft. Note the two spark plugs per cylinder pair. (W. R. Pearce image)

The N.4 engine had a 3.74 in (95 mm) bore and a 5.91 (150 mm) stroke. The engine displaced 519 cu in (8.51 L) and produced 80 hp (60 kW) at 1,200 rpm and 90 hp (67 kW) at 1,600 rpm. The N.4 was 54 in (1.38 m) wide, 32 in (.82 m) long, 22 in (.57 m) tall, and weighed 441 lb (200 kg). No information has been found to indicate that the engine was installed in any aircraft.

After surviving so many close calls, Mario Faccioli was sadly killed in a plane crash in March 1915. The type of aircraft involved in the crash is not known. Aristide Faccioli never achieved the success he strived for and never recovered from his son’s death. He took his own life on 28 January 1920.

SPA-Faccioli N.3 and N.4 engines are preserved and on display in the Museo Storico dell’Aeronautica Militare in Vigna di Valle, Italy. An N.4 engine is displayed in the Museum of Applied Arts & Sciences, Museums Discovery Centre in Castle Hill, Australia. The museum lists the engine as a “300 hp, model 2-A,” undoubtedly confusing the eight-cylinder SPA-Faccioli engine with a SPA Type 2-A straight-eight engine. Also, the N.4 is positioned upside-down in its display stand.

SPA-Faccioli N4 rear

This rear view of the N.4 engine shows how the cross shaft also acted as the camshaft and directly drove the pushrods. The valves in the foreground are for the intake. The port for the intake manifold can just be seen at the center of the engine. Note the mounts for the magnetos and that the engine is upside-down in its display stand. (Museum of Applied Arts & Sciences image)

Origin of Aviation in Italy by Piero Vergnano (1964)
Aeronuatica Militare Museo Storico Catalogo Motori by Oscar Marchi (1980)
Jane’s All the World’s Aircraft 1912 by Fred T. Jane (1912/1968)


Tips Aero Motor Rotary Aircraft Engines

By William Pearce

From a very early age, Maurice A. Tips and his younger brother Ernest Oscar were interested in aviation. By 1909, the Belgian siblings had built their first aircraft: a canard-design, pusher biplane. The first engine installed in the aircraft proved underpowered and was replaced with a Gnome rotary. The engine was geared to two shafts, each driving a two-blade pusher propeller. Although the aircraft made some flights, its handling was unsatisfactory, and the design was not developed further. The aircraft did possess unique concepts, a theme continued in Maurice’s subsequent designs.


Rear view of Maurice and Ernest Oscar Tips’ 1909 biplane pusher. The aircraft was unable to fly with its original Pipe V-8 engine, but the lighter Gnome rotary enabled the aircraft to takeoff. Note the central gearbox that provided power to the shafts that turned the propellers via right-angle drives.

After the 1909 aircraft, Maurice refocused his efforts on aircraft engines. By 1911, Maurice had designed the first in a series of “valveless” rotary engines. All of Tips’ engines used a rotary valve system for cylinder intake and exhaust. Unfortunately, documentation on these engines is nearly non-existent; their exact order of development and specifications are not known with certainty.


Drawings of the 25 hp (19 kW) Tips engine of 1912. Air was drawn through the rotating suction tubes (5) which enable the intake port (14) and exhaust port (13) to align with the cylinder. The suction tubes were geared (9 and 10) to the stationary crankshaft (4).

The first engine was a seven-cylinder rotary that produced 25 hp (19 kW). The engine had a 2.76 in (70 mm) bore, a 4.33 in (110 mm) stroke, and a displacement of 181 cu in (3.0 L). Hollow “suction tubes” took the air/fuel mixture from the engine’s crankcase and delivered it to the cylinders. Each suction tube was geared to the engine’s fixed crankshaft. The suction tubes would spin at half the speed of the crankcase as it rotated. The top of the suction tube had two passageways. Each passageway would align with a common port near the top of the cylinder once every two revolutions of the crankcase. One passageway aligned to allow the air/fuel mixture to flow from the suction tube and into the cylinder. The second passageway aligned to allow the exhaust gases to flow from the cylinder out into the atmosphere.

The 25 hp (19 kW) Tips “valveless” rotary engine was installed in a monoplane built by Henri Gérard. It appears the aircraft was completed around 1913. However, the performance results of the engine and aircraft have not been found. As history unfolded, this was the only Tips engine installed in an aircraft.

Maurice and EO Tips Gerard monoplane

Henri Gérard and his mechanic by Gérard’s Tips-powered monoplane. The engine was a 25 hp (19 kW) seven-cylinder “valveless” rotary. Note the spark plug protruding from the top of each cylinder. (Tips Family Archive via Vincent Jacobs)

Maurice continuously refined the design of “valveless” rotary engines. In late 1912, two larger versions of the seven-cylinder engine were planned. A 50 hp (37 kW) version had a 4.33 in (110 mm) bore, a 4.72 in (120 mm) stroke, and a displacement of 487 cu in (8.0 L). The largest engine produced 70 hp (52 kW) and had a 4.41 in (112 mm) bore, a 5.12 in (130 mm) stroke, and a displacement of 547 cu in (9.0 L). An advertisement stated that all three engines would be displayed at the Salon de l’Automobile held in Brussels, Belgium in January 1913. In addition, the 25 hp (19 kW) engine was used to power a Tips airboat that was displayed at the show.

Engine development continued throughout 1913 and 1914. The most obvious change was that the suction tube was moved to be parallel with the cylinder, rather than at an angle as seen in the earlier engines. The newer engine design had an updated drive for the suction tubes, and the air/fuel mixture no longer passed through the crankcase; rather, it was delivered through a hollow extension of the crankshaft to a space under the suction tubes. A nine-cylinder engine of this design was built, but it is not clear if the engine was built in Europe or the United States; it was most likely built in the US.


The 1913 (left) and 1914 (right) versions of the Tips rotary engine. The major changes were to the suction tube drive and rotary valve. The small tube (no. 14 on the 1913 engine and no. 40 on the 1914 engine) in the stationary crankshaft extension provided oil to the crankshaft and connecting rod.

When World War I broke out, Maurice and Ernest Tips fled Belgium. Ernest made his way to Britain, where he worked with Charles Richard Fairey and helped start the Fairey Aviation Company in 1915. Ernest would return to Belgium in 1931 to start the Fairey subsidiary, Avions Fairey. He also produced the Tipsy series of light aircraft.

Maurice Tips traveled to the US in October 1915 and continued to design aircraft engines. It is quite possible that the nine-cylinder engine was built once Tips had established himself in the US. The engine had a 4.92 in (125 mm) bore and a 5.91 in (150 mm) stroke. It displaced 1,011 cu in (16.6 L) and produced 110 hp (82 kW). The nine-cylinder engine was approximately 35 in (.89 m) in diameter and weighed 290 lb (132 kg). A smaller nine-cylinder engine was designed, but it is not clear if it was built. The smaller engine had a 4.92 in (125 mm) bore and a 5.51 in (140 mm) stroke. It displaced 944 cu in (15.5 L) and produced 100 hp (75 kW).

Tips 9-cylinder rear

Rear view of the 110 hp (82 kW) nine-cylinder Tips “valveless” rotary engine. Air was drawn in through the hollow extension to the crankshaft where it mixed with fuel. Ports in the crankshaft extension led to a distribution chamber at the back of the engine. The air/fuel mixture was drawn into the suction tube behind each cylinder and then into the combustion chamber. (Tips Family Archive via Vincent Jacobs)

For more power, Maurice had the idea of coupling two 110 hp (82 kW) nine-cylinder engines in tandem to make an 18-cyinder power unit. The two engine sections would be placed front-to-front and rotate in the same direction. The engines would be suspended some 20 in (508 mm) below the propeller shaft. A Renold Silent (inverted tooth) drive chain positioned between the two engines would deliver power to the propeller shaft. By varying the size of the drives, a propeller speed reduction could be achieved. Drawings show a 5 in (127 mm) drive gear and a 7.5 in (191 mm) gear on the propeller shaft, which would give a .667 speed reduction. The tandem 18-cylinder engine had an output of 220 hp (164 kW) and was 606 lb (275 kg). The power unit was 62 in (1.57 m) long and 40 in (1.02 m) in diameter, not including the propeller shaft. It is unlikely that a tandem engine was built.

In 1917, The Tips Aero Motor Company was founded in Woonsocket, Rhode Island. That same year, Maurice applied for patents covering his new engine design, which incorporated many concepts from the earlier engines. Rather than a tandem engine, the new Tips engine was a single, 18-cylinder power unit. The rotary engine had two rows of nine cylinders and was housed in a stationary frame. The new engine employed both water and air cooling. The cylinders were arranged in pairs, with one in the front row of the engine and the other in the rear row. The crankshaft had only one throw, and the pistons for both cylinders in a pair were at top dead center on their compression strokes at the same time. The engine’s compression ratio was 5.25 to 1. Each cylinder had one spark plug at the center of its combustion chamber. The spark plugs were fired by two magnetos mounted to the front of the engine and driven from the propeller shaft.

Tips Tandem 18-cylinder engine

The Tips Tandem engine consisted of two nine-cylinder engines coupled together. An inverted tooth chain between the engines delivered power to the propeller shaft. (Tips Family Archive via Vincent Jacobs)

Most rotary engines had a fixed crankshaft and a crankcase that rotated. This arrangement created much stress on the crankshaft and crankcase and also imposed severe gyroscopic effects on the aircraft. The Tips engine employed several unique characteristics to resolve the drawbacks of traditional rotary engines. The crankshaft of the Tips engine rotated and was geared to the propeller shaft. The propeller shaft was geared to the crankcase, which allowed it to rotate in the opposite direction from the crankshaft and propeller. The end result was that when the crankshaft was turning at 1,800 rpm, the propeller would turn at 1,080 rpm, and the crankcase would rotate at 60 rpm in the opposite direction. Rotary engines in which the crankshaft and crankcase rotate in opposite directions and at different speeds are often called bi-directional or differential rotary engines.

The propeller shaft of the Tips 18-cylinder engine was geared to the crankshaft at a .600 reduction; the crankshaft gear had 18 teeth, and the propeller shaft’s internal gear had 30 teeth. For crankcase rotation, the 17 teeth on the propeller shaft gear engaged 51 teeth on one side of a countershaft to give a .333 gear reduction. The other side of the countershaft had 11 teeth that meshed with a 66-tooth internal gear attached to the crankcase and resulted in a further .167 reduction. Having the propeller and crankshaft rotating in opposite directions not only eliminated the gyroscopic effect inherent to conventional rotary engines, but it also neutralized the gyroscopic effect created by the propeller attached to a fixed engine.


The 18-cylinder Tips engine of 1917 was far more complex than the earlier engines. Note the paired cylinders separated by the rotary valve (24). The propeller shaft (10) was geared to the crankshaft (7) via reduction gears (8 and 9). The crankcase was geared to the propeller shaft via a countershaft (16).

On the exterior of the cylinder castings were numerous cooling fins. In addition, internal passageways for water cooling were in the cylinder castings. Between each pair of cylinders were a series of air passageways to further augment cooling. The engine did not have a water pump; rather, thermosyphoning and the relatively slow rotation of the crankcase enabled the circulation of cooling water from the internal hot areas of the cylinders out toward the cooling fins on the exterior of the cylinders. The engine’s rotation also aided oil lubrication from the pressure-fed crankshaft to the rest of the engine. The oil pump and carburetor were located on the stationary frame at the rear of the engine.

A flange was positioned on the crankshaft, between the connecting rods of the cylinder pair. Mounted on the flange via ball bearings was an eccentric gear with 124 teeth on its outer edge. Attached (but not fixed) to the crankcase was a master valve gear that had 128 teeth on its inner edge. The gears meshing with an eccentric action resulted in the master valve gear turning four teeth per revolution of the crankshaft. On the outer edge of the master valve gear was a bevel gear with 128 teeth. These teeth engaged a 16-tooth pinion attached to a rotary valve positioned between each cylinder pair. The four teeth per revolution of the master valve gear acting on the 16-tooth rotary valve resulted in the rotary valve turning at a quarter engine speed. Each hollow rotary valve had two intake ports and two exhaust ports.


On the left is the rotary valve shown with the intake ports aligned (Fig 3). The air/fuel mixture entered the valve through ports in its lower end (27a). On the right is the valve with the exhaust ports aligned (Fig 5). Fig 4 shows a cross section of the rotary valve with intake ports (28), exhaust ports (29), and passageways for the flow of cooling water (30). Fig 8 shows the valve gear drive. The crankshaft (7) turned an eccentric gear (44) that meshed (42 and 41) with a gear mounted to the crankcase. The result is that a bevel gear (27) engaged a gear screwed to the bottom of the rotary valve (26 on Fig 3) and turned the valve once for every four revolutions of the crankshaft.

Air was drawn in through a carburetor at the rear of the engine. The air/fuel mixture flowed through a manifold bolted to the cylinder casting and into a passageway that led to a chamber around the lower part of the rotary valve. Holes in the valve allowed the air to flow up through its hollow middle and into the cylinder when the intake ports aligned. As the valve rotated, the exhaust ports would align with the cylinder, allowing the gases to escape out the top of the valve head and into the atmosphere. Passageways in the lower part of the rotary valve head brought in cooling water from the cylinder’s water jacket. Water flowed up through the rotary valve and back into the cylinder’s water jacket. The rotary valve was lubricated by graphite pads and held in place by a spiral spring and retaining cap around its upper surface.

The 18-cylinder Tips engine had a 4.5 in (114 mm) bore and a 6.0 in (152 mm) stroke. The engine displaced 1,718 cu in (28.1 L) and produced 480 hp (358 kW) at 1,800 rpm. The Tips engine weighed 850 lb (386 kg). At speed, the engine consumed 22 gallons (83 L) of fuel and 3 gallons (11 L) of oil per hour. The oil consumption was particularly high, even for a rotary engine, but the Tips engine was larger and more powerful than other rotary engines.


Rear view of the 480 hp (358 kW) Tips engine shows the extensive fining (22) that covered the engine. The fining and air passages (23) combined to turn the whole engine into a radiator to cool the water that flowed through the engine via thermosyphoning and centrifugal force.

In 1919, the engine was mentioned in a few publications. In 1920, Leo G. Benoit, Technical Manager at Tips Aero Motors, passed away. Benoit was said to be in charge of the engine’s design and construction. No further information regarding the engine and no images of the engine have been found. This lack of information could mean that the 480 hp (358 kW) Tips engine was never built. However, given the detailed description of the engine and that it was worked on from 1917 to at least 1920, the possibility certainly exists that the engine was built and tested.

Sometime before World War II, Maurice Tips returned to Belgium. He continued to design engines and applied for a patent on a rotary piston engine in 1938. This engine was not designed for aircraft use and bore no similarities to his early aircraft engines.

Tips 18-cylinder engine crankcase

Maurice Tips stands next to the unfinished crankcase casting for the 18-cylinder differential rotary engine. The holes in the crankcase’s outer diameter were for the rotary valves. The holes in the crankcase’s face were for water radiators, and the holes inside of the crankcase were for the cylinders. It is not known if a complete engine was built. (Tips Family Archive via Vincent Jacobs)

Les Avions Tipsy by Vincent Jacobs (2011)
– “Valveless Rotary Combustion Engine” US Patent 1,051,290 by Maurice Tips (granted 21 January 1913)
– “Improvements in Rotary Combustion Engines” GB Patent 191307778 by Maurice Tips (application 15 April 1913)
– “Improvements in or relating to Rotary Combustion Engines” GB Patent 191506821 by Maurice Tips (application 8 May 1914)
– “Rotary Valve” US Patent 1,286,149 by Maurice A. Tips (granted 26 November 1918)
– “Internal Combustion Engine” US Patent 1,306,035 by Maurice A. Tips (granted 10 June 1919)
– “Valve-Operating Mechanism” US Patent 1,306,036 by Maurice A. Tips (granted 10 June 1919)
– “Internal Combustion Engine” US Patent 2,203,449 by Maurice Tips (granted 4 June 1940)
– “The Tips 480 H.P. Aero Motor” Aerial Age Weekly (17 March 1919)
Airplane Engine Encyclopedia by Glenn Angle (1921)

Paradox side

Deissner ‘Paradox’ Rotary Aircraft Engine

By William Pearce

Deissner Paradox running

Charles (Carl) Deissner stands next to the 30 hp (22 kW) Paradox engine during a test run. The frame around the engine enabled it to be run in such demonstrations and was not needed when the engine was installed in an aircraft (which probably never happened). Note the carburetor at the front of the engine.

As early aviators began to take flight, it quickly became apparent that most engines were not suitable for use in aircraft. A number of engineers and designers worked to create light and powerful engines that were ideal for aircraft use. Some of these designs, such as the Antoinette, lay the foundation for many engines to follow, but other engine designs were quickly abandoned. Like many others, Charles (Carl) Deissner of London, England designed one of the engines destined to go nowhere. Deissner called his engine the Paradox.

The Paradox was an air-cooled, four-cylinder, four-stroke, rotary engine. In this context, “rotary” refers to a radial engine in which the crankcase and cylinders rotate around the crankshaft. This is not to be confused with a Wankel engine, which uses a rotor spinning in a fixed crankcase to produce power. Most rotary aircraft engines had the crankshaft fixed to the airframe, while the propeller was attached to and spun with the crankcase. However, the Paradox was not like other rotary engines.

While the crankcase of the Paradox rotated just like any other rotary engine, inside the Paradox, the crankshaft turned at twice the speed of the crankcase and in the same direction. The engine’s internals were kept in order by eccentric gears on the crankshaft engaging ring gears inside the crankcase. The stroke of the crankshaft represented one quarter of the piston’s stroke. The path of the eccentric gear also represented one quarter of the piston’s stroke. The relative motions of the crankcase and crankshaft enabled the full stroke to be utilized and allowed the unique Paradox engine to function.

Paradox engine sectional

Sectional view of the 30 hp (22 kW) Paradox engine. The valves can be seen on the front of the L-head cylinders. Below the valves are the pushrods actuated by counter-weighted rockers. The rockers are driven by a short camshaft extending on each side of a pinion. The pinion rotates as its teeth mesh with a gear fixed to a stationary shaft at the front of the engine.

The easiest way to visualize the Paradox engine’s operation is to consider the piston at the top of the cylinder when the cylinder is at the 12 o’clock position. Here, the crankshaft and its throw are at top dead center. When the engine has rotated 180 degrees, putting the cylinder at the six o’clock position, the crankshaft has rotated 360 degrees. The crankshaft is again at top dead center, but since the cylinder is now at the bottom of the engine, the piston is now at the bottom of the cylinder. When the engine has rotated another 180 degrees, the cylinder is back at the 12 o’clock position, and the crankshaft, having rotated 360 degrees, is again at top dead center, returning the piston to the top of the cylinder.

The crankshaft had two throws 180 degrees apart, and each throw served a pair of cylinders. The cylinders of each pair were 180 degrees apart, and the two cylinder pairs were 90 degrees apart. A non-articulating, solid connecting rod served each cylinder pair so that when one piston was at the top of the cylinder, the piston in the opposite cylinder was at the bottom of the cylinder. Deissner stated that since the connecting rod did not articulate, Paradox engines could be made with relatively long strokes and achieve high compression ratios.

Paradox side

The 30 hp (22 kW) Paradox engine complete with propeller. Note the skew gear-driven magneto, counter-weighted rocker arms, and the cylinders’ L-head design.

Three versions of the Paradox engine were planned for construction with different outputs: 30 hp (22 kW), 70 hp (52 kW), and 100 hp (75 kW). However, it appears only the 30 hp (22 kW) and 70 hp (52 kW) engines were actually built. While both engines had four cylinders and shared the same rotary and eccentric crankshaft arrangement, each engine also had a number of unique features.

The 30 hp (22 kW) Paradox was a demonstration engine mounted in a metal frame. The engine utilized an L-head cylinder with side valves. The single intake and exhaust valves were positioned on the front side of the cylinder. Each valve was actuated by a pushrod driven by a large, counter-weighted rocker arm. Part of the rocker rode on a camshaft that extended through the axis of a pinion. The cam on one side of the pinion controlled the intake while the cam on the other side controlled the exhaust. The pinion was driven by a skew gear mounted on a stationary shaft that did not rotate with the engine.

Induction air was brought in through a carburetor at the front of the engine. The air/fuel mixture then passed through the crankcase, where it was warmed, and into separate manifolds for each cylinder. Exhaust was taken through a manifold from each cylinder, piped through the crankcase, and vented out the front of the engine’s propeller shaft, which was fixed to the crankcase.

Paradox Induction Exhaust

Schematic view of the induction and exhaust system in the 70 hp (52 kW) Paradox engine. For clarity, the valves are illustrated on the front and rear of the T-head cylinder, rather than its sides. Note the offset crankshaft.

A magneto was driven by a skew gear at the rear of the engine. The magneto fired the one spark plug installed in each cylinder. However, it appears the engine could accommodate two spark plugs per cylinder. Ball bearings were used throughout the engine. The 30 hp (22 kW) Paradox engine had a 2.76 in (70 mm) bore and a 7.17 in (182 mm) stroke. The engine displaced 171 cu in (2.8 L). Its 30 hp (22 kW) output was obtained at 1,200 rpm. Increasing the engine’s rpm to 1,400 resulted in an output of 40 hp (30 kW).

The 70 hp (52 kW) Paradox engine also used side valves but in a T-head arrangement, with the valves on opposite sides of the cylinder. The valves were actuated by the same method used on the 30 hp (22 kW) engine, but a pushrod and rocker was now positioned on each side of the cylinder. One schematic shows the valves on the front and back sides of the cylinder, rather than the left and right sides. This was most likely done for illustrative purposes, to show how the engine’s induction and exhaust systems worked. Induction air was brought in the front of the engine, passed through the crankcase (where it was warmed), and flowed through a fixed shaft at the rear of the engine. Here, it passed through a carburetor, and the air/fuel mixture flowed back through the shaft to manifolds at the rear of the engine; these manifolds led to each cylinder. The 70 hp (52 kW) Paradox engine had a 4.0 in (102 mm) bore and a 7.0 in (178 mm) stroke. The engine displaced 352 cu in (5.8 L). Its 70 hp (52 kW) output was obtained at 1,400 rpm, and it produced 60 hp (45 kW) at 1,200 rpm. The engine weighed 220 lb (100 kg).

Deissner Paradox Ad

1910 advertisement for the Paradox engine expressing its many virtues over other rotary engines. The pricing for the 70 hp (52 kW) engine is given, although the 30 hp (22 kW) engine is illustrated in the photograph. The price of the 70 hp (52 kW) engine was increased to £460 in March 1911. (via

The 30 hp (22 kW) Paradox engine was running by late 1910. It was run both with and without a 7 ft 6 in (2.3 m) Eta propeller. Some of the engine’s noted advantages were that standard lubricating oil could be used—other rotaries typically needed castor oil. The Paradox engine was also said to have good fuel economy, but no specifics were given. In early 1911, the 30 hp (22 kW) engine broke free during a test run, resulting in a destroyed propeller and a damaged engine. The engine was repaired in February, and the 70 hp (52 kW) Paradox engine was to be finished by March 1911. However, no further information has been found regarding any Paradox engine.

The Paradox engines may have offered some improvements in oil consumption, which was always quite high with standard rotaries, but its other unique features did not offer any tangible advantage over more popular engines. Rotary engines would continue to be widely used until after World War I. At that time, conventional engines had out-powered the rotary, and the inherent limitations of its spinning crankcase design could not be overcome.

– “The Paradox Rotary Engine” Flight (19 November 1910)
The Art of Aviation by Robert W. A. Brewer (2nd edition, 1911)

Antoinette VII with 100hp V-16 engine paris 1909

Antoinette (Levavasseur) Aircraft Engines

By William Pearce

Léon Levavasseur was one of those rare geniuses of early aviation who designed and built engines as well as aircraft. In the early 1900s, Levavasseur gave up his career as an electrical engineer to focus on aviation. He needed funding to pursue his interests, so in August (some say July) 1902, Levavasseur approached industrialist and fellow Frenchman Jules Gastambide. Levavasseur had impressed and then befriended Gastambide when he repaired generators at one of Gastambide’s power plants. At the July meeting, Levavasseur outlined his plans for an aircraft of his design to be powered by a new engine that he was also designing. Levavasseur suggested the new enterprise should be named Antoinette, after Gastambide’s young daughter. Gastambide was interested but thought the engine should be built first, as no aircraft had yet flown. Levavasseur was agreeable, and with financial backing secured, he set to work on the new engine.

Antoinette IV 50hp V-8 Latham Levavasseur Camp Chalons 5 June 1909

An Antoinette mechanic (left), Hubert Latham (middle), and Léon Levavasseur (right) with an Antoinette IV aircraft powered by a 50 hp (37 kW) Antoinette V-8 at Camp de Châlons in early June 1909. At the event, Latham flew continuously for 1:07:37, setting a French endurance record. Note the condenser under the aircraft’s wing.

Levavasseur quickly returned to Puteaux (near Paris), France, and set up a shop to work on the new engine. On 28 August 1902, Levavasseur applied for a secret patent on his engine, which consisted of eight cylinders laid out in a Vee pattern, forming two banks of four cylinders. This patent application became public on 28 August 1903 and was granted French patent no 399,068 on 30 September 1904.

From 1902 through 1910, Levavasseur produced several different Antoinette engines, but they all used the same basic layout. Technically, the first time the “Antoinette” name was applied during the Levavasseur-Gastambide partnership was in 1905 when a series of boats were so named. It would not be until 1906 that the Société Anonyme Antoinette was officially incorporated.

All of Levavasseur’s engines consisted of individual, water-cooled cylinders arranged in a 90 degree Vee on an aluminum crankcase. The cylinders were staggered on the crankcase to facilitate the use of side-by-side connecting rods. With this arrangement, the connecting rods for each left and right cylinder pair attached to the crankshaft on the same crankpin. This allowed the engine to be much shorter than if each connecting rod had its own crankpin. The connecting rods were of a tubular design, and the pistons were made from cast iron.

Cody Antoinette 50hp V-8 Nulli Secundus 1907

A 1907 image of Samuel Cody with a 50 hp (37 kW) Antoinette V-8 in the framework of the “Nulli Secundus,” Britain’s first airship.

Each cylinder had one intake and one exhaust valve positioned on the Vee side of the cylinder. The intake valve was situated above the exhaust valve, creating an “F-head” or “Intake Over Exhaust” (IOE) cylinder head. The intake valve was atmospheric (automatic)—drawn open by the vacuum created in the cylinder as the piston moved down. The exhaust valve was actuated by a pushrod driven by the camshaft located in the Vee of the engine. The top of the cylinder’s combustion chamber was hemispherical, with a single spark plug positioned at its center.

The Antoinette engines used a primitive type of direct fuel injection. A belt-driven fuel pump at the rear of the engine fed fuel into a small reservoir (injector) located above each intake valve. When the intake valve opened, the suction that drew in air also pulled in fuel from the reservoir via a narrow, capillary passageway .008 in (.2 mm) in diameter. By manipulating the fuel pump, the pilot could exert a certain degree of fuel flow regulation. However, the system had some issues, and Antoinette engines had difficulty running at low rpm. In addition, the small passageways in the “injectors” easily became clogged by impurities in the fuel. These complications led some Antoinette operators to convert the engine to a carbureted induction system.

To cool a normal Antoinette engine, a belt-driven water pump at the rear of the engine provided water to an inlet at the base of each cylinder on the outer side of the engine. The water then passed up through the water jacket and along the cylinder barrel. The water exited the top of the cylinder on the Vee side of the engine, where it flowed into a common manifold for each cylinder bank. The water was then taken to a radiator or to a reservoir tank, as engine cooling was not critical on very short flights.

Antoinette 50hp V-8 London Science Museum

This 50 hp (37 kW) Antoinette V-8 engine is on display at the Science Museum in London and may have been used by Cody in 1908 for the first flight in Britain. Note the aluminum cylinder heads, brass water jackets, and copper water manifolds. The fuel distributor can be seen on each vertical intake pipe. (Warbird Tails image)

For lubrication, oil was taken from the crankcase and pumped through a pipe inside the crankcase, just above the camshaft. The pipe ran the length of the engine and was pierced with numerous small holes. Oil sprayed from the pipe, lubricating all of the engine’s internal components. Any components not in direct contact with an oil spray were lubricated by the oil mist created inside the crankcase.

Some (but not all) of the Antoinette engines had the ability to reverse their running. This was particularly helpful for braking and maneuvering in dirigibles. The camshaft was normally locked into its driving gear at the rear of the engine. With the engine stopped, the camshaft could be unlocked, rotated 90 degrees, and locked into a second position in its driving gear. One position was for normal (counter-clockwise) rotation, and the other was for reverse rotation (clockwise).

Antoinette engine ad V-16

Antoinette engine ad circa 1907 illustrating the lightness of the 220 lb (100 kg), 100 hp (75 kw) V-16 engine.

Each Antoinette engine was made to the highest standards in a shop that boasted of tolerances down to .0004 in (.01 mm). Another feature of all Antoinette engines was that their components were engineered to be just strong enough for their individual tasks. By designing parts with operating stresses in mind, all extra material could be eliminated, resulting in complete engines that were much lighter than their contemporaries. This design philosophy also had a drawback: engine reliability could suffer because parts were more easily overstressed, resulting in a failure. Antoinette engines were relatively specialized, and when one was in need of repair, it had to be shipped back to the factory.

The early Antoinette engines used open cylinder barrels made from cast iron. An aluminum cylinder head was bolted to the barrel. Each cylinder had a spun brass water jacket shrink-fitted to the cylinder head. The engine’s spark plugs were fired by a battery-powered ignition coil distributor.

Levavasseur’s first engine was running by the end of 1902, but efforts to improve the engine were undertaken throughout 1903. The engine was a V-8 with a 5.12 in (130 mm) bore and stroke. The engine’s total displacement was 842 cu in (13.8 L), and it produced 80 hp (60 kW). Initially, the engine weighed 346 lb (157 kg), but refinements brought the weight down to 320 lb (145 kg).

Antoinette V-16 engine display

An Antoinette V-16 engine possibly in storage at the Musée de l’Air et de l’Espace in Le Bourget, France. Note how the V-16 utilized all the same components as the V-8, with the exception of the crankcase, crankshaft, camshaft, and water manifolds. This engine has rather unusual exhaust stacks. (image source)

The 80 hp (60 kW) Levavasseur engine underwent a military test in March 1903 in which it produced 63 hp (50 kW). This output was derived by using a alternative power calculation method, and Levavasseur objected to the results. A little later, the engine was tested again, using another power calculation method. During this test, the engine registered an output of 82 hp (61 kW). The engine’s performance and Levavasseur’s ideas sufficiently impressed General Louis André, France’s Minister of War, who then provided 20,000 Francs of secret funds to Levavasseur for the construction of his airplane.

From July to September 1903, Levavasseur built his airplane in Villotran, France, which is why the aircraft became known as the Aéroplane de Villotran. The aircraft was powered by the 80 hp (60 kW) engine. Unfortunately, the aircraft proved incapable of flight. By 15 September 1903, Levavasseur had decided the aircraft was a failure; the engine was removed, and the aircraft was burned.

Antoinette V-24 marine engine

The 360 hp (268 kW) Antoinette V-24 marine engine of 1906. Unlike the V-16 engines, the V-24 appears to be comprised of V-8 engine sections. The engine is labeled as follows: A) air intake pipe; B) exhaust; C) cooling water outlet; D) aluminum cylinder head; E) steel cylinder covered with a brass water jacket sleeve; F and G) ignition distributors; H) spark plug; h) cylinder head bolts; I) fuel distributor to the intake valve; J) cooling water inlet; K) cylinder mounting bolt; P) engine mounting flange; S and T) gears for the ignition distributors; U) crankshaft gear; V) camshaft gear.

The Aéroplane de Villotran’s failure to fly, and the fact that no other aircraft had yet flown, made the concept of an aircraft engine seem futile. However, Levavasseur and Gastambide knew the engine held great potential and turned to motorboat racing as a way for the engine to prove its worth. From 1904 through 1906, Levavasseur’s engines powered a number of motorboats that achieved various distance speed records. It was to some of these motorboats that the “Antoinette” name was first given. In some cases, V-8 engines were coupled in tandem to create a more substantial power unit. By 1908, the Antoinette company had ended its support for motorboat racing and focused on using its engines only for aviation.

In 1904, while his engine was beginning to gain fame, Levavasseur designed other engines. Using the 80 hp (60 kW) V-8 as a foundation and maintaining the 5.12 in (130 mm) bore and stroke, Levavasseur designed V-16, V-24, and V-32 engines. Levavasseur believed that engines with many cylinders created frequent power pulses that smoothed out the engine’s operation and caused less stress on its internal components. The V-16 displaced 1,685 cu in (27.6 L) and produced 155 hp (116 kW). The V-24 displaced 2,527 cu in (41.4 L) and produced 225 hp (168 kW). The V-32 was most likely never built, but it would have displaced 3,370 cu in (55.2 L) and produced around 300 hp (224 kW).

Bleroit IX 50hp V-16 1908

A Bléroit IX aircraft under construction in 1908 with a 50 hp (37 kW) Antoinette V-16 installed in its frame. From left to right, the Bléroit mechanics are Louis Peyret, Louis Paragot, M. Pelletier, Alfred Bertrand, and Julien Mamet.

Levavasseur also varied the bore and stroke to make engines of different sizes and power. In 1905, Levavasseur built a V-8 Antoinette engine with a 3.15 in (80 mm) bore and stroke for aviation pioneers Ferdinand Ferber and Alberto Santos-Dumont. The engine displaced 196 cu in (3.2 L) and produced 24 hp (18 kW). The engine went through some refining and eventually weighed only 79 lb (36 kg). Another V-8 used a 4.13 in (105 mm) bore and stroke to displace 444 cu in (7.3 L). This engine produced 50 hp (37 kW) and weighed 176 lb (80 kg). The engine was approximately 32 in (.81 m) long, 24 in (.62 m) wide, and 22 in (.55 m) tall. A large V-8 was also built with a 7.87 in (200 mm) bore and stroke. Undoubtedly for marine use, this engine displaced 3,067 cu in (50.3 L), produced 200 hp (149 kW), and weighed 838 lb (380 kg).

In 1906, Levavasseur built a large V-24 Antoinette engine for marine use. The V-24 had a 5.91 in (150 mm) bore and stroke and displaced 3,882 cu in (63.6 L). The engine produced 360 hp (268 kW) and weighed some 1,322 lb (600 kg). Some sources say this engine was too heavy for the intended boat, which ended up sinking. The specifics of this incident have not been found.

Antoinette 50hp V-8 engine Krakow

A later model 50 hp (37 kW) Antoinette V-8 with an extended propeller shaft on display at the Muzeum Lotnictwa Polskiego in Krakow, Poland. Note the different lengths of the air intake pipes and that the water jackets are made from copper. (Alan Wilson image)

An Antoinette automobile made its debut in the 1906 Salon de l’Automobile in Paris, and some Antoinette engines were built for automotive use, these being a slightly different design and heavier than the aviation engines. Adams Manufacturing Company in London built a small number of the automotive engines under license for cars they were manufacturing.

By 1907, V-16 versions of the 3.15 in (80 mm) bore/stroke and 4.13 in (105 mm) bore/stroke engines were being built. The 3.15 in (80 mm) bore and stroke V-16 displaced 393 cu in (6.4 L), produced 50 hp (37 kW), and weighed around 143 lb (65 kg). The 4.13 in (105 mm) bore and stroke V-16 displaced 888 cu in (14.5 L), produced 100 hp (75 kW), and weighed 220 lb (100 kg). The 100 hp V-16 engine’s approximate dimensions were 55 in (1.40 m) long, 24 in (.62 m) wide, and 22 in (.55 m) tall.

Antoinette engines circa1907

The basic specifications of various Antoinette engines available circa 1907.

In addition to the V-16 engines listed above, Levavasseur offered Antoinette V-8 engines with five bore/stroke combinations. The V-8 engines had bores/strokes of 3.15, 4.13, 5.12, 5.91, or 7.87 in (80, 105, 130, 150, or 200 mm); the smallest two were mainly used for aviation.

It seems that around 1908 Levavasseur ceased experimenting with different engines and began working to refine the popular types. Levavasseur incorporated many changes to the Antoinette engines, but not all of the changes were applied at the same time. An elongated propeller shaft housing of approximately 12 in (.30 m) was cast integral with the crankcase. This feature made for a very aesthetically pleasing installation when the engine was used in an Antoinette aircraft. The battery-powered coil ignition was replaced by an accumulator and high-frequency distributor. A new one-piece, steel cylinder was used in which the cylinder head was integral with the cylinder barrel. This construction allowed for a higher compression ratio. New one-piece water jackets made of either brass or copper surrounded the new cylinders. The water jacket was unusual in that it was made by electrolytically depositing metal onto a wax mold that had been coated with graphite as a conductive material. The wax was then melted out, leaving a formed water jacket as thin as .04 in (1 mm). While this method of construction could yield perfect parts, it was expensive, and there was a high rejection rate because of irregularities in the water jacket wall.

Antoinette VII with 100hp V-16 engine paris 1909

Antoinette VII aircraft with a 100 hp (75 kW) V-16 engine displayed at the Salon de l’Aeronautique in 1909. Most sources indicate the condenser used aluminum tubes and copper side manifolds, details that this image seems to support.

By 1908, Levavasseur had perfected a zero-loss steam-cooling method for the Antoinette engines that were installed in Antoinette aircraft. The system used the same basic routing as the normal cooling system, but the water was allowed to boil in the water jackets. The steam was then collected and sent to a water separating tank. From the tank, the steam was sent though large condensers made of aluminum tubing with copper side manifolds. The condensers were positioned horizontally on each side of the aircraft. The steam condensed back to water and was routed back to the separating tank by a second pump. From the separating tank, the water was pumped back to the engine. The system condensed .26 gallons (1 L) of water per minute, and its capacity was 3.17 gallons (12 L). By reducing the amount of water needed, the steam-cooling method weighed less than conventional water-cooling.

Four Antoinette engines were displayed at the first Paris Salon de l’Aeronautique, starting in December 1908. A V-8 and V-16 were still offered with bores and strokes of 3.15 in (80 mm). However, the engines’ weights had increased to 93 lb (42 kg) for the V-8 and 165 lb (75 kg) for the V-16. The other two engines were a V-8 and V-16 with a bore of 4.33 in (110 mm) and a stroke of 4.13 in (105 mm). The V-8 engine displaced 487 cu in (8.0 L) and weighed 209 lb (95 kg). The V-16 engine displaced 974 cu in (16.0 L) and weighed 264 lb (120 kg). Some sources list the larger bore engines as producing 50 hp (37 kW) and 100 hp (75 kW) respectively. However, other sources give the outputs as 67 hp (50 kW) and 134 hp (100 kW). Note that the kW values (50 and 100) of the second figures match the hp values of the first figures. Possibly a printing error, the higher power figures have been found in fairly early publications and have been repeated a number of times over the years. The weight increases for all four engines were a result of strengthening components to increase Antoinette engine reliability.

Antoinette 50hp V-8 close up

A late model 50 hp (37 kW) Antoinette V-8 on display in the Musée de l’Air et de l’Espace. Note that this engine used brass water jackets; the piping and water manifolds were made from copper. (Aerofossile2012 image)

Alberto Santos-Dumont, Paul Cornu, Louis Blériot, Gabriel and Charles Voisin, Henri Farman, Léon Delagrange, Samuel Cody, and Hubert Latham are just some of the pioneers who used Antoinette engines to power their flying machines and themselves into the record books. Outside of the Wright brothers, almost all early aviation “firsts” were achieved in machines powered by an Antoinette engine. It was a 100 hp (75 kW) V-16-powered Antoinette aircraft that Latham flew during the aviation meet at Reims, France in August 1909 and for the Gordon Bennett Cup at Belmont Park, New York in October 1910.

With the success of the engine, Levavasseur began to focus entirely on building aircraft. From 1908 on, little engine development was undertaken to keep the Antoinette engines at the forefront of aviation. The Antoinette aircraft were built with the same spare-no-expense mentality as the engines, which resulted in them being priced far above the competition. To make matters worse, the aircraft proved to be a challenge to fly. At the same time, other engine manufactures closed the developmental gap, and the expensive Antoinette engines were no longer the coveted power plant they once were. These factors conspired to put the Antoinette company out of business in 1912.

Latham Antoinette VII 100hp V-16 NY 1910

Latham’s 100 hp (75 kW) V-16-powered Antoinette VII aircraft at Belmont Park, New York in October 1910 for the Gordon Bennett Cup. Note the length of the condenser, which extends some 13 ft (4 m) along the side of the aircraft.

While Levavasseur was most likely the first to build a V-8 engine, it is a near certainty that he was the first to create V-16 and V-24 engines. Very little information can be found regarding the V-24 marine engine. Some sources state that Levavasseur also built a V-32 intended for marine use, while other sources claim the engine did not proceed past the design phase.

Some sources state that Levavasseur also built V-12 and V-20 engines. These engines, especially the V-20, depart from Levavasseur’s known engine layout with a V-8 at its core. While no photographs of Levavasseur’s V-12 (or V-32) engine have been found, the V-20 engine does still exist (albeit as a table). The V-20’s cylinders, valves, and valve train do not match any other engine built by Levavasseur. There was a commonality of components and configuration from Levavasseur’s earliest engine of 1903 to his last of circa 1910. The components that make up the V-20, reportedly built in 1905, are unique to that engine and are not common with any other Levavasseur engine. This component incompatibility would lead some to conclude that the V-20 engine was not built by Levavasseur.

Antoinette VII with 50hp V-8 Musee du Bourge

An Antoinette VII aircraft with a 50 hp (37 kW) V-8 engine on display in the Musée de l’Air et de l’Espace. Note how well the engine fits into the aircraft and that the condensers appear to be made entirely of copper. For cooling, steam flowed from the top of the water jackets into a separation tank. The steam then flowed from the tank into the condenser, where it returned to water. The water was then pumped from the condenser into the bottom of the separation tank and back to the engine. (Pline image)

Levavasseur’s Antoinette engines were essentially the first commercially available aircraft engine and represented the pinnacle of performance in the early days of aviation. Just about every early European aviation pioneer’s first flight was powered by an Antoinette, but the engines’ reliability left much to be desired. While some changes were incorporated over the years, and their reliability did improve, the basic engine did not change much. Just before 1910, other engines (the Gnome rotary in particular) offered similar power for a similar weight but were often more reliable than the Antoinettes.

Note: Many sources give similar but completely different values for Antoinette engine dimensions, bores, strokes, and outputs. Some discrepancies can be attributed to numerous unit conversions being applied, and some of the power discrepancies can be attributed to the engines having different outputs at different rpms. Sadly, it seems that detailed specifics were not recorded in those early days of aviation; therefore, there can be no absolute certainty about the various Antoinette engine models or their histories.

V-20 engine

The V-20 engine as displayed at Le Manoir de l’Automobile et des Vieux Métiers in Lohéac, France. Regardless of the V-20’s origins, it seems rather inglorious for such machinery to be turned into furniture. However, the engine would have probably been scrapped long ago had it not found favor as a conversation piece. Apparently, its conversion to a table consisted of nothing more than bolting on legs to preexisting mounts, something that could easily be reversed for a more befitting display. (ZANTAFIO56 image)

Bléroit: Herald of an Age by Brain A. Elliot (2000)
Les moteurs et aéroplanes Antoinette by Gérard Hartmann (13 August 2007) 7.4 MB pdf in French
The Art of Aviation by Robert W. A. Brewer (1910)
The Passion That Left the Ground by Stephen H. King (2007)
Vingt Cinq Ans d’Aéronautique française: 1907-1932 Tome 1 (1934)
– “The First Paris Aeronautical Salon: Engines for Aeroplanes” Flight (16 January 1909)
– “How Levavasseur Built his Light Motor” by Ferdinand Ferber The Automobile (28 March 1907)
– “Historie du moteur Antoinette” by Ferdinand Ferber l’Aérophile (15 February 1908)
– “Moteur à huit cylindres” French patent 339,068 by Léon Levavasseur (applied 28 August 1903)
– “Carbureter” US patent 878,297 by Léon Levavasseur (applied 16 may 1907)
– “Umsteuerungsvorrichtung für Mehrzylinder-Explosionskraftmaschinen” Austrian patent 25,610 by Léon Levavasseur (applied 14 September 1904)
Airplane Engine Encyclopedia by Glenn Angle (1921)

Roberts 6-X engine side

Roberts Motor Company Aircraft Engines

By William Pearce

In the early 1900s, the Roberts Motor Company of Sandusky, Ohio made a series of two-stroke engines for boats. With aviation gaining popularity, it was only natural for the company to adapt its engines for aircraft use. Roberts aircraft engines first appeared in 1911 and were designed by the company’s founder and president Edmund W. Roberts.

Roberts 4-X engine Smithsonian

A four-cylinder Roberts 4-X engine on display at the Smithsonian National Air and Space Museum in Washington, DC. Note the tubular housing to which the carburetor is attached. Inside the housing is the tubular distributor sleeve for delivering the air/fuel mixture to the cylinders. The water pump is mounted on the upper rear of the housing. (National Air and Space Museum image)

Roberts Motor Company’s aircraft engines differed from their marine counterparts in that they were engineered to be as light as possible. To keep parts (and associated points of failure) to a minimum, the Roberts two-stroke engines did not use poppet valves. In addition, Roberts’ engines incorporated unique designs to overcome drawbacks generally found with two-stroke engines, namely the air/fuel mixture pre-igniting as it entered the cylinder, causing a backfire.

The engines’ cast cylinder liners were constructed of a proprietary alloy called “Aerolite,” which Roberts said was as light as aluminum but twice as strong and had the wear properties of cast iron. The individual cylinder liners were covered by an aluminum water jacket. A ring around the base of the cylinder liner would fit into a recess around the bottom of the water jacket, securing the two together. The cylinder liner’s spark plug boss (and that of the decompressor if present) passed through the water jacket casting. The outer diameter of the boss was threaded, and a nut secured the top of the water jacket and cylinder liner. This nut would also draw up the base of the liner into the water jacket, securing the whole cylinder assembly.

Roberts 6-X engine side

The six-cylinder Roberts 6-X engine. The crankcase casting provided a space under each cylinder for the air/fuel mixture. Each space was sealed by crankshaft main bearings. Note the two exhaust ports for each cylinder.

The pistons were made of cast iron and were attached to drop forged I-beam connecting rods made of vanadium steel. The connecting rods were attached to the crankshaft by a bronze strap about a third the size of the crankpin. (Firing every revolution, the pistons of a two-stroke engine are not pulled down by the crankshaft and therefore do not need a full-size connecting rod bearing cap.) The crankshaft was hollow and made of drop forged steel. The cylinders were secured to the crankcase by four bolts, with adjacent cylinders sharing their bolts. The crankcase was made from Magnalium, an aluminum and magnesium alloy that made it lighter and stronger than an aluminum crankcase of the same thickness.

The carburetors were mounted to a tubular housing that ran along the right side of the engine. Inside of this housing was a tubular distributor sleeve (also called a rotary induction valve) driven by an intermediate gear that engaged the accessory drive gear mounted on the end of the crankshaft. The distributor sleeve rotated at crankshaft speed and had ports to control the air/fuel mixture flow from the carburetor into the crankcase. The crankcase was constructed so that a small space existed under each cylinder for the incoming charge. The carburetor aligned with multiple ports in the distributor sleeve to allow a constant flow into the distributor, but each cylinder matched up with a single port to control air/fuel delivery. For each cylinder, the incoming charge passed from the distributor though a port in the side of the crankcase. The distributor helped eliminate the risk of backfires and distributed the air/fuel mixture equally to all the cylinders, allowing the engine to run smoothly.

Roberts 4-X Rotary Distributor

The tubular distributor sleeve of a Roberts 4-X engine. The ports at the center of the tube aligned with the carburetor.

The distributor port opened as the piston moved up and drew in the air/fuel mixture. The port then closed as the piston moved down on its power stroke, compressing the incoming charge underneath. Two ports in the piston aligned with ports in the cylinder wall when the piston was near bottom dead center. This alignment allowed the pressurized, incoming air/fuel mixture to flow from the crankcase into a space on the outer side of the cylinder. In this space, Roberts installed what they called a “cellular by-pass” to prevent backfires. The incoming charge flowed through the cellular by-pass and then through another set of ports positioned above the piston. The piston’s top had a large deflector to send the incoming air charge toward the top of the combustion chamber to improve exhaust gas scavenging. This deflector was positioned on the intake port side of the piston. Two exhaust ports were located on the opposite side of the cylinder from the intake ports and were also controlled by the piston so that all ports were uncovered when the piston was near bottom center.

The cellular by-pass was a series of flat and corrugated plates creating a honeycomb mesh. The large surface area of the cellular by-pass extinguished any flame should a backfire occur, but it did not decrease the engine’s efficiency in normal operation. The Roberts engine’s resistance to backfiring allowed a leaner mixture to be used, thus increasing the engine’s fuel economy. The cellular by-pass also helped mix and vaporize the fuel in the incoming charge.

Roberts 6-X parts Weeks

Various parts for one of the two Roberts 6-X replica engines built for Kermit Weeks. Note the deflector on the top of the pistons and the two ports in the side of the pistons. A decompressor valve can be seen on the top of the cylinder in the lower left corner. (Fantasy of Flight image)

The water pump was mounted at the right rear of the engine and was driven from the gear driving the tubular distributor sleeve. The pump drew water from the radiator and then pushed it through a passageway on the right side of the crankcase. Each cylinder had an open port that aligned with a coolant passageway in the crankcase. The water flowed into a small channel in the cylinder and then around the exhaust ports and up into the cylinder’s water jacket. It then flowed out the top of the cylinder and into a manifold that led back to the radiator. The engine was lubricated by the oil and fuel mixing and via splash lubrication. Grease cups were used to lubricate the main bearings.

A single spark plug was mounted in the center of each cylinder’s semi-hemispherical combustion chamber. The spark plug was fired by a Bosch magneto mounted at the rear of the engine. The magneto was driven by a helical gear via the intermediate gear that meshed with the accessory drive gear on the end of the crankshaft. An advance fork mounted above the magneto shaft moved the helical gear of the magneto along its shaft to either advance or delay ignition—an adjustment that could be made by the pilot while in flight.

Roberts 6-X gears Weeks

The exposed accessory gears of the Robert 6-X replica. The crankshaft drove an intermediate gear, the backside of which engaged the magneto drive shaft. To advance or delay the timing, the helical gear for the magneto drive shaft could be adjusted by the brass advance fork above it. The intermediate gear drove the gear for the tubular distribution sleeve, which in turn drove the gear for the water pump. (Fantasy of Flight image)

The Roberts four-cylinder engine was known as the 4-X. It had a 4.5 in (114 mm) bore, a 5 in (127 mm) stroke, and a total displacement of 318 cu in (5.2 L). The engine produced 50 hp (37 kW) at 1,200 rpm. It used one carburetor, and its magneto turned at twice crankshaft speed. Its crankshaft was 2.5 in (64 mm) in diameter, with crankpins 1.75 in (44 mm) in diameter and 2.5 in (64 mm) long. The crankshaft was supported by five main bearings; the one toward the propeller was 6.375 in (162 mm) long. The crankshaft was 40 in (1,016 mm) long and weighed 17.5 lb (7.9 kg). The 4-X was 40.5 in (1.03 m) long, 25 in (.64 m) tall, 24 in (.61 m) wide, and weighed 170 lb (77 kg).

The six-cylinder engine was known as the 6-X. Like the 4-X, it had a 4.5 in (114 mm) bore and a 5 in (127 mm) stroke. The engine’s total displacement was 477 cu in (7.8 L), and it produced 75 hp (56 kW) at 1,200 rpm. The 6-X used two carburetors, and its magneto turned at three times crankshaft speed. Its crankshaft and crankpins were the same size as the 4-X’s. The crankshaft was supported by seven main bearings, was 52 in (1,321 mm) long, and weighed 27.5 lb (12.5 kg). The 6-X was 52.5 in (1.33 m) long, 25 in (.64 m) tall, 24 in (.60 m) wide, and weighed 240 lb (109 kg).

Roberts 6-XX engine

The Roberts 6-XX engine with exhaust manifolds and enclosed accessory gears.

A further development of the six-cylinder engine was the 6-XX. This engine had its accessory gears covered and bathed in oil. Its bore and stroke were enlarged to 5.5 in (140 mm) and 6 in (152 mm) respectively. The 6-XX’s total displacement was 588 cu in (14.0 L), and it produced 125 hp (93 kW) at 1,100 rpm. The engine used two carburetors. Its Bosch HL magneto turned at 1.5 times crankshaft speed to fire one of the two spark plugs in each cylinder. The other spark plug was fired by a Delco distributor. The 6-XX’s crankshaft was 3 in (76 mm) in diameter, with crankpins 2.5 in (64 mm) in diameter and 3.5 in (99 mm) long. The crankshaft was supported by seven main bearings; the one toward the propeller was 12 in (305 mm) long. The 6-XX was approximately 60.5 in (1.54 m) long, 27.5 in (.70 m) tall, 24 in (.60 m) wide, and weighed 390 lb (177 kg).

The Roberts engines were refined over time and used by a good number of early aviation pioneers. By 1913, all Roberts engines had the exposed accessory gears enclosed like those on the 6-XX engine. This change necessitated the magneto be repositioned. The cylinder liners were now made of cast iron, and the water jackets were made of Aerolite. The pistons were also made of Aerolite, which reduced their weight by over 2 lb (.9 kg) each. The tubular distributor sleeve was mounted on four sets of ball bearings to reduce friction. Dual ignition, like that used on the 6-XX, was available as an option on the 6-X engine. A starting crank attached to the end of the crankshaft was also an option.

Roberts 6-X 1913 rear

The rear of the 1913 Roberts 6-X engine showing the enclosed accessory gears, repositioned magneto, and optional hand starting crank on the end of the engine. The decompressors can be seen on the top of the cylinders. These were used to make starting the engine easier.

As two-stroke Roberts engines were surpassed by new four-stroke engines, like the Curtiss OX-5 and Hispano-Suiza 8, the company struggled to keep up. By 1918, the 6-X engine had its bore and stroke increased to 5 in (127 mm) and 5.5 in (140 mm) respectively, giving a total displacement of 648 cu in (10.6 L). The tubular distributor was replaced by more conventional intake manifolds, and the engine produced 100 hp (75 kW) at 1,200 rpm. The 6-X now weighed 368 lb (167 kg).

There is also some indication that a V-12 was planned and possibly constructed by Roberts in the late 1910s. This engine was known as the E-12. It had a 6 in (152 mm) bore, a 6.5 in (165 mm) stroke, and a total displacement of 2,205 cu in (36 L). The engine produced 350 hp (261 kW) at 1,200 rpm. Each cylinder had its own crankpin, and 13 main bearings supported the crankshaft. The E-12 weighed 990 lb (490 kg).

Roberts 6-X Weeks

One of Weeks’ Roberts 6-X replica engines. The engines were built to power a replica Benoist XIV flying boat. The Benoist is a pusher, which is why the outlet for the coolant pipe is toward the propeller shaft. Note the brass grease cups for lubricating the crankshaft main bearings. The cover on each cylinder is for the cellular by-pass. (Fantasy of Flight image)

The Roberts Motor Company left the aviation field by 1919 to focus on marine engines. Around this time, the company changed its name to Roberts Motors. A few years later, Roberts Motors went out of business. A number of early Roberts four- and six-cylinder aircraft engines still exist in museums.

Recently, Kermit Weeks of Fantasy of Flight in Polk City, Florida commissioned the creation of two replica Roberts 6-X engines. One of the engines was a test engine, and the other would be installed in a Benosit XIV flying boat replica. An original engine was reverse engineered, allowing these engines to be built. Below is a video from 2013 of Mr. Weeks checking on the progress of the Roberts 6-X engine construction at Vintage & Auto Rebuilds in Chardon, Ohio. Both Roberts 6-X replica engines have since been completed and test run.


Roberts Aviation Motors by The Roberts Motor Co. (1912)
– “Construction of Cylinder of Internal Combustion Engines” US patent 1,210,537 by Edmund W. Roberts (granted 2 January 1917)
The 1913 Model 6-X by The Roberts Motor Co. (1913)
Fantasy of Flight Blog (various entries relating to the Roberts engine and Benoist flying boat replica)
Aerosphere 1939 by Glenn Angle (1940)
(Jane’s) All the World’s Aircraft 1918 by C. G. Grey (1918)