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Gnome Monosoupape

December 18, 2023

The Monosoupape (French for single-valve), was a rotary engine design first introduced in 1913 by Gnome Engine Company (renamed Gnome et Rhône in 1915). It used a clever arrangement of internal transfer ports and a single pushrod-operated exhaust valve to replace the many moving parts found on more conventional rotary engines, and made the Monosoupape engines some of the most reliable of the era. British aircraft designer Thomas Sopwith described the Monosoupape as "one of the greatest single advances in aviation".[1]

Monosoupape
A 1917 Gnome 9N 160 hp Monosoupape rotary engine, with dual ignition provision. Diameter is 95cm (37.4 in)
Type Rotary aero engine
National origin France
Manufacturer Gnome et Rhône
First run 1913
Major applications Airco DH.2
Nieuport 28

Monosoupape engines were produced under license in large numbers in Britain, Russia, Italy and the US. Two differing nine-cylinder versions were produced, the 100 hp (75 kW) 9B-2 and 160 hp (120 kW) 9N, with differing displacements giving the larger displacement 9N version a nearly-cylindrical shaped crankcase, with the 9N also adopting a dual ignition system for increased flight safety.

2,188 units were produced under license in Britain, with an uprated 120 hp (89 kW) version later built in Russia and the Soviet Union, two of which flew the Soviet TsAGI-1EA single lift-rotor helicopter in 1931–32.[2][3]

Background edit

Unlike other rotaries, the early Gnome engines like the Gnome Omega, Lambda and Delta used a unique arrangement of valves in order to eliminate pushrods that operated during the inlet phase of the combustion cycle on more conventional engines. Instead, a single exhaust valve on the cylinder head was operated by a pushrod that opened the valve when the pressure dropped at the end of the power stroke. A pressure-operated inlet valve, which was balanced by a counterweight to equalize the centrifugal forces, was placed in the centre of the piston crown, where it opened to allow the fuel–air charge to enter from the engine's central crankcase.

Although ingenious, the system had several drawbacks: the cylinder heads had to be removed to perform maintenance of the intake valves, and to adjust the timing correctly. Fuel economy suffered in comparison to other rotaries because the inlet valves could not be opened and closed at the ideal times.

Design edit

In 1913, Louis Seguin and his brother Laurent (engineers who founded the Société Des Moteurs Gnome [the Gnome motor company] in 1905) introduced the new Monosoupape series, which eliminated the inlet valve, replacing it with piston-controlled transfer ports similar to those found in a two-stroke engine. Beginning with the power stroke, the four-stroke engine operated normally until the piston was just about to reach the bottom of its stroke (bottom dead center, or BDC), when the exhaust valve was opened "early". This let the still-hot burnt combustion gases "pop" out of the engine while the piston was still moving down, relieving exhaust pressure and preventing exhaust gases from entering the crankcase. After a small additional amount of travel, the piston uncovered 36 small ports around the base of the cylinder, leading to the crankcase which held additional fuel–air mixture (the charge). No transfer took place at this point since there was no pressure differential; the cylinder was still open to the air and thus at ambient pressure. The overhead valve exhausted directly into the slipstream since no exhaust manifold could be practically fitted to the spinning crankcase and cylinders. The lack of an exhaust manifold also saved weight and prevented excessive gyroscopic forces in flight.

During the exhaust stroke, scavenging occurred as the air moving past the cylinder exterior lowered the pressure inside due to the direct exposure of the exhaust port to the slipstream. The piston continued its exhaust stroke until top dead center (TDC) was reached, but the valve remained open. The piston began to move down on its intake stroke with the valve still open, pulling new air into the cylinder. It remained open until it was two-thirds of the way down, at which point the valve closed and the remainder of the intake stroke greatly reduced the air pressure. When the piston uncovered the transfer ports again, the low pressure in the cylinder drew in the balance of the charge.

The charge was an overly rich mixture of air, which was acquired through the hollow crankshaft, and fuel that was continuously injected by a fuel nozzle on the end of a fuel line, entering the crankcase through the hollow crankshaft. The nozzle was in the proximity of, and aimed at, the inside base of the cylinder where the transfer ports were located. The fuel nozzle was stationary with the crankshaft, and the cylinders rotated into position in turn. The compression stroke was conventional.

The spark plug was installed horizontally into the rear of the cylinder at the top but had no connecting high-voltage wire. An internal-tooth ring gear mounted on the engine drove a stationary magneto mounted on the firewall, whose high-voltage output terminal was in close proximity to the spark plug terminals as they passed by. This arrangement eliminated the need for distributor and high-voltage wiring found in conventional mechanically timed ignition systems. This ring gear also drove the oil pump, which supplied oil to all bearings, and through hollow pushrods to the rockers and valves and also drove an air pump which pressurized the fuel tank. The later 160 hp (120 kW) Gnome 9N engines had dual ignition systems for safety, with twin spark plugs per cylinder which were electrically wired, with the wires routed onto the crankcase and a central pair of magnetos driven by the spinning engine crankcase.

Control edit

Monosoupapes therefore had a single petrol regulating control used for a limited degree of speed regulation. In early examples, engine speed could be controlled by varying the opening time and extent of the exhaust valves using levers acting on the valve tappet rollers, but this was later abandoned due to causing burning of the valves.[2] Instead, a blip switch was used, which cut out the ignition when pressed. This was used sparingly to avoid fouling the spark plugs, since it was only safe to be used when the fuel supply was also cut. The later 160 CV output 9N subtype also featured an unusual method of functioning with its integral dual-ignition setup, that allowed output values of one-half, one-quarter and one-eighth power levels to be achieved through use of the coupe-switch and a special five-position rotary switch that selected which of the trio of alternate power levels would be selected when the coupe-switch was depressed, allowing it to cut out all spark voltage to all nine cylinders, at evenly spaced intervals to achieve the multiple levels of power reduction.[4] The airworthy reproduction Fokker D.VIII parasol monoplane fighter at Old Rhinebeck Aerodrome, uniquely powered with a Gnome 9N, often demonstrates the use of its Gnome 9N's four-level output capability in both ground runs[5] and in flight.

Lubrication edit

 
The Sopwith Tabloid reproduction shows the sheet-metal cowling used to redirect the oil sprayed by the rotating engine.

The lubrication system, as with all rotary engines, was a total-loss type in which castor oil was pumped into the fuel–air mix. Castor oil was used because it did not readily dissolve into the fuel, and because it offered lubrication qualities superior to other available oils. Over two gallons of castor oil were sprayed into the air during each hour of engine operation. This explains why most rotaries were fitted with cowls, with the lowermost quarter omitted to direct the spray of castor oil away from the pilot.[6] Unburnt castor oil from the engine had a laxative effect on the pilot if ingested.[7]

Because the entire engine rotated, it had to be precisely balanced, requiring precision machining of all parts. As a result, Monosoupapes were extremely expensive to build, the 100 hp (75 kW) models costing $4,000 in 1916 (approx. $89,000 in 2017 dollars). However, they used less lubricating oil and weighed slightly less than the earlier two-valve engines.[8]

Variants edit

Gnome Monosoupape 7 Type A
(1916) seven-cylinder rotary engine, 80 hp (60 kW). Bore and stroke: 110 mm × 150 mm (4.3 in × 5.9 in) .
Gnome Monosoupape 9 Type B-2
(1916) nine-cylinder rotary engine, 100 hp (75 kW). Bore and stroke: 110 mm × 150 mm (4.3 in × 5.9 in).
Gnome Monosoupape 11 Type C
An 11 cylinder version
Gnome Monosoupape 9 Type N
(1917) nine-cylinder rotary engine, larger diameter crankcase than the B-2, 150 or 160 hp (112 or 119 kW), increasing capacity to 15.8 L (960 cu in). Bore and stroke: 115 mm × 170 mm (4.5 in × 6.7 in).
Gnome Monosoupape 9 Type R
180 hp nine-cylinder rotary engine, development of 9N with same 170 mm (6.7 in) stroke.

Applications edit

List from Lumsden.

Monosoupape 7 Type A edit

Monosoupape 9 Type B edit

Monosoupape 9 Type N edit

Engines on display edit

Specifications (Monosoupape 9 Type B-2) edit

Data from Lumsden.

General characteristics

Components

  • Valvetrain: Single overhead valve with cylinder ports
  • Fuel type: 40-50 Octane petrol
  • Oil system: Total loss, castor oil
  • Cooling system: Air-cooled
  • Reduction gear: Direct drive, right-hand tractor, left-hand pusher

Performance

  • Power output: 86 kW (115 hp) at 1,300 rpm (Maximum power)
  • Compression ratio: 4.85:1

See also edit

Comparable engines

Related lists

References edit

Citations edit

  1. ^ Nahum, Andrew (1999). The Rotary Aero Engine. NMSI Trading Ltd. ISBN 1-900747-12-X.
  2. ^ Savine, Alexandre. "TsAGI 1-EA." 2009-01-26 at the Wayback Machine ctrl-c.liu.se, 24 March 1997. Retrieved 12 December 2010.
  3. ^ video
  4. ^ Murrin, Fred; Phillips, Terry. "(A) Look at the Gnôme 9N Rotary Engine". kozaero.com. KozAero. Retrieved August 13, 2021. In order to keep the engine running smoothly on reduced power settings, it was necessary for the selector switch to cut out all cylinders at evenly spaced intervals. It was also beneficial to have all cylinders firing periodically to keep them warm and to prevent the spark plugs from fouling with oil. The selector switch has five positions, zero (0) for off and four running positions, one through four (1-4) (see Photo 5). The Gnôme 9N had two magnetos (and two spark plugs per cylinder) and the selector switch was wired to the right magneto only, so it was necessary for the pilot to turn off the left magneto if he wanted to change the speed of the engine.
  5. ^ (YouTube). Old Rhinebeck Aerodrome: Sholom. August 4, 2019. Event occurs at 0:12 to 2:00. Archived from the original on August 13, 2021. Retrieved August 13, 2021.{{cite AV media}}: CS1 maint: bot: original URL status unknown (link)
  6. ^ Gnome Monosoupape Type N Rotary Retrieved on 18 February 2009.
  7. ^ Setright, IJK (1971). The Power to Fly : The Development of the Piston Engine in Aviation. Allen and Unwin. p. 27. ISBN 978-0043380413.
  8. ^ Vivian, E. Charles (2004). A History of Aeronautics. Kessinger Publishing. p. 255. ISBN 1419101560.
  9. ^ "New England Air Museum".
  • McCutcheon, Kimble D. (PDF). Aircraft Engine Historical Society. Archived from the original (PDF) on 2008-07-06. Retrieved 2008-05-01.

Bibliography edit

  • Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6.

External links edit

 
Wikimedia Commons has media related to Gnome Monosoupape.
  • Rattling of a Gnome engine
  • Ground run of a rare 100 hp Monosoupape in Australia
  • YouTube video of 100 hp Gnome Monosoupape demonstration
  • Modern reproduction Fokker D VIII powered with 160 hp Gnome Monosoupape
  • New Zealand-built (21st century) reproduction Type 9B-2 100 hp Monosoupape running
  • Classic Aero Machining Service/CAMS Reproduction Gnôme Type 9B-2 Monosoupape reproduction engine development video
  • Computer video of how the 100 CV Type 9B-2 Monosooupape Goes Together
  • Koz-Aero's "Look at the Gnome 9N Monosoupape" Article

December 18, 2023
gnome, monosoupape, monosoupape, french, single, valve, rotary, engine, design, first, introduced, 1913, gnome, engine, company, renamed, gnome, rhône, 1915, used, clever, arrangement, internal, transfer, ports, single, pushrod, operated, exhaust, valve, repla. The Monosoupape French for single valve was a rotary engine design first introduced in 1913 by Gnome Engine Company renamed Gnome et Rhone in 1915 It used a clever arrangement of internal transfer ports and a single pushrod operated exhaust valve to replace the many moving parts found on more conventional rotary engines and made the Monosoupape engines some of the most reliable of the era British aircraft designer Thomas Sopwith described the Monosoupape as one of the greatest single advances in aviation 1 MonosoupapeA 1917 Gnome 9N 160 hp Monosoupape rotary engine with dual ignition provision Diameter is 95cm 37 4 in Type Rotary aero engineNational origin FranceManufacturer Gnome et RhoneFirst run 1913Major applications Airco DH 2Nieuport 28Monosoupape engines were produced under license in large numbers in Britain Russia Italy and the US Two differing nine cylinder versions were produced the 100 hp 75 kW 9B 2 and 160 hp 120 kW 9N with differing displacements giving the larger displacement 9N version a nearly cylindrical shaped crankcase with the 9N also adopting a dual ignition system for increased flight safety 2 188 units were produced under license in Britain with an uprated 120 hp 89 kW version later built in Russia and the Soviet Union two of which flew the Soviet TsAGI 1EA single lift rotor helicopter in 1931 32 2 3 Contents 1 Background 2 Design 2 1 Control 2 2 Lubrication 3 Variants 4 Applications 4 1 Monosoupape 7 Type A 4 2 Monosoupape 9 Type B 4 3 Monosoupape 9 Type N 5 Engines on display 6 Specifications Monosoupape 9 Type B 2 6 1 General characteristics 6 2 Components 6 3 Performance 7 See also 8 References 8 1 Citations 8 2 Bibliography 9 External linksBackground editUnlike other rotaries the early Gnome engines like the Gnome Omega Lambda and Delta used a unique arrangement of valves in order to eliminate pushrods that operated during the inlet phase of the combustion cycle on more conventional engines Instead a single exhaust valve on the cylinder head was operated by a pushrod that opened the valve when the pressure dropped at the end of the power stroke A pressure operated inlet valve which was balanced by a counterweight to equalize the centrifugal forces was placed in the centre of the piston crown where it opened to allow the fuel air charge to enter from the engine s central crankcase Although ingenious the system had several drawbacks the cylinder heads had to be removed to perform maintenance of the intake valves and to adjust the timing correctly Fuel economy suffered in comparison to other rotaries because the inlet valves could not be opened and closed at the ideal times Design editIn 1913 Louis Seguin and his brother Laurent engineers who founded the Societe Des Moteurs Gnome the Gnome motor company in 1905 introduced the new Monosoupape series which eliminated the inlet valve replacing it with piston controlled transfer ports similar to those found in a two stroke engine Beginning with the power stroke the four stroke engine operated normally until the piston was just about to reach the bottom of its stroke bottom dead center or BDC when the exhaust valve was opened early This let the still hot burnt combustion gases pop out of the engine while the piston was still moving down relieving exhaust pressure and preventing exhaust gases from entering the crankcase After a small additional amount of travel the piston uncovered 36 small ports around the base of the cylinder leading to the crankcase which held additional fuel air mixture the charge No transfer took place at this point since there was no pressure differential the cylinder was still open to the air and thus at ambient pressure The overhead valve exhausted directly into the slipstream since no exhaust manifold could be practically fitted to the spinning crankcase and cylinders The lack of an exhaust manifold also saved weight and prevented excessive gyroscopic forces in flight During the exhaust stroke scavenging occurred as the air moving past the cylinder exterior lowered the pressure inside due to the direct exposure of the exhaust port to the slipstream The piston continued its exhaust stroke until top dead center TDC was reached but the valve remained open The piston began to move down on its intake stroke with the valve still open pulling new air into the cylinder It remained open until it was two thirds of the way down at which point the valve closed and the remainder of the intake stroke greatly reduced the air pressure When the piston uncovered the transfer ports again the low pressure in the cylinder drew in the balance of the charge The charge was an overly rich mixture of air which was acquired through the hollow crankshaft and fuel that was continuously injected by a fuel nozzle on the end of a fuel line entering the crankcase through the hollow crankshaft The nozzle was in the proximity of and aimed at the inside base of the cylinder where the transfer ports were located The fuel nozzle was stationary with the crankshaft and the cylinders rotated into position in turn The compression stroke was conventional The spark plug was installed horizontally into the rear of the cylinder at the top but had no connecting high voltage wire An internal tooth ring gear mounted on the engine drove a stationary magneto mounted on the firewall whose high voltage output terminal was in close proximity to the spark plug terminals as they passed by This arrangement eliminated the need for distributor and high voltage wiring found in conventional mechanically timed ignition systems This ring gear also drove the oil pump which supplied oil to all bearings and through hollow pushrods to the rockers and valves and also drove an air pump which pressurized the fuel tank The later 160 hp 120 kW Gnome 9N engines had dual ignition systems for safety with twin spark plugs per cylinder which were electrically wired with the wires routed onto the crankcase and a central pair of magnetos driven by the spinning engine crankcase Control edit Monosoupapes therefore had a single petrol regulating control used for a limited degree of speed regulation In early examples engine speed could be controlled by varying the opening time and extent of the exhaust valves using levers acting on the valve tappet rollers but this was later abandoned due to causing burning of the valves 2 Instead a blip switch was used which cut out the ignition when pressed This was used sparingly to avoid fouling the spark plugs since it was only safe to be used when the fuel supply was also cut The later 160 CV output 9N subtype also featured an unusual method of functioning with its integral dual ignition setup that allowed output values of one half one quarter and one eighth power levels to be achieved through use of the coupe switch and a special five position rotary switch that selected which of the trio of alternate power levels would be selected when the coupe switch was depressed allowing it to cut out all spark voltage to all nine cylinders at evenly spaced intervals to achieve the multiple levels of power reduction 4 The airworthy reproduction Fokker D VIII parasol monoplane fighter at Old Rhinebeck Aerodrome uniquely powered with a Gnome 9N often demonstrates the use of its Gnome 9N s four level output capability in both ground runs 5 and in flight Lubrication edit nbsp The Sopwith Tabloid reproduction shows the sheet metal cowling used to redirect the oil sprayed by the rotating engine The lubrication system as with all rotary engines was a total loss type in which castor oil was pumped into the fuel air mix Castor oil was used because it did not readily dissolve into the fuel and because it offered lubrication qualities superior to other available oils Over two gallons of castor oil were sprayed into the air during each hour of engine operation This explains why most rotaries were fitted with cowls with the lowermost quarter omitted to direct the spray of castor oil away from the pilot 6 Unburnt castor oil from the engine had a laxative effect on the pilot if ingested 7 Because the entire engine rotated it had to be precisely balanced requiring precision machining of all parts As a result Monosoupapes were extremely expensive to build the 100 hp 75 kW models costing 4 000 in 1916 approx 89 000 in 2017 dollars However they used less lubricating oil and weighed slightly less than the earlier two valve engines 8 Variants editGnome Monosoupape 7 Type A 1916 seven cylinder rotary engine 80 hp 60 kW Bore and stroke 110 mm 150 mm 4 3 in 5 9 in Gnome Monosoupape 9 Type B 2 1916 nine cylinder rotary engine 100 hp 75 kW Bore and stroke 110 mm 150 mm 4 3 in 5 9 in Gnome Monosoupape 11 Type C An 11 cylinder version Gnome Monosoupape 9 Type N 1917 nine cylinder rotary engine larger diameter crankcase than the B 2 150 or 160 hp 112 or 119 kW increasing capacity to 15 8 L 960 cu in Bore and stroke 115 mm 170 mm 4 5 in 6 7 in Gnome Monosoupape 9 Type R 180 hp nine cylinder rotary engine development of 9N with same 170 mm 6 7 in stroke Applications editList from Lumsden Monosoupape 7 Type A edit Avro 504 Avro 511 Bristol Coanda G B 75 Sopwith PupMonosoupape 9 Type B edit Avro 504 Airco DH 2 Airco DH 5 Blackburn Scout Blackburn Twin Blackburn Blackburn Triplane Bristol Coanda T B 8 Bristol Scout FBA Type B Flying boat Nieuport IV Royal Aircraft Factory B E 8 Royal Aircraft Factory F E 8 Short S 80 Short Type C Sopwith Sociable Sopwith Type 807 Folder Seaplane Sopwith Two Seat Scout Sopwith Schneider Sopwith Pup Sopwith F 1 Camel Vickers Gunbus FB 2 3 5 6 and 7 Vickers F B 12 Vickers F B 19 Bullet TsAGI 1EA ru helicopter licence built as M 2 Monosoupape 9 Type N edit Nieuport 28 Sopwith Camel Morane Saulnier AI Orenco BEngines on display editA nine cylinder Monosoupape engine is on public display at the Royal Air Force Museum London A nine cylinder Monosoupape engine is on public display at the Aerospace Museum of California A seven cylinder Monosoupape engine is on display at Solent Sky One Monosoupape built by Peter Hooker England is on display at the Museo Nacional de Aeronautica Moron Argentina It is used during exhibitions to explain the rotary engines systems as it shows its operative internal parts There is a restored B 2 Monosoupape on display at the New England Air Museum Bradley Int l Airport Windsor Locks CT USA 9 TAVAS in Australia have two http www tavas com au rotary engine php Archived 2014 10 22 at the Wayback Machine Both for exhibition in flying aircraft A restored Monosoupape 9 Type N is on display in the Reynolds Alberta Museum An original unrestored running nine cylinder Monosoupape engine is on public display at the South Australian Aviation Museum in South Australia A video of it running can be found at https www saam org au engines htmlSpecifications Monosoupape 9 Type B 2 editData from Lumsden General characteristics Type 9 cylinder single row rotary engine Bore 110 mm 4 3 in Stroke 150 mm 5 9 in Displacement 12 8 L 780 cu in Length 107 4 cm 42 3 in Diameter 95 cm 37 in Dry weight 137 4 kg 303 lb Components Valvetrain Single overhead valve with cylinder ports Fuel type 40 50 Octane petrol Oil system Total loss castor oil Cooling system Air cooled Reduction gear Direct drive right hand tractor left hand pusherPerformance Power output 86 kW 115 hp at 1 300 rpm Maximum power Compression ratio 4 85 1See also editGnome Omega Delta and Lambda earlier seven cylinder Gnome designs with inlet valve in piston crown Comparable engines Bentley BR1 Clerget 7Z Clerget 9B Le Rhone 9J Oberursel U IRelated lists List of aircraft enginesReferences editCitations edit Nahum Andrew 1999 The Rotary Aero Engine NMSI Trading Ltd ISBN 1 900747 12 X Savine Alexandre TsAGI 1 EA Archived 2009 01 26 at the Wayback Machine ctrl c liu se 24 March 1997 Retrieved 12 December 2010 video Murrin Fred Phillips Terry A Look at the Gnome 9N Rotary Engine kozaero com KozAero Retrieved August 13 2021 In order to keep the engine running smoothly on reduced power settings it was necessary for the selector switch to cut out all cylinders at evenly spaced intervals It was also beneficial to have all cylinders firing periodically to keep them warm and to prevent the spark plugs from fouling with oil The selector switch has five positions zero 0 for off and four running positions one through four 1 4 see Photo 5 The Gnome 9N had two magnetos and two spark plugs per cylinder and the selector switch was wired to the right magneto only so it was necessary for the pilot to turn off the left magneto if he wanted to change the speed of the engine Old Rhinebeck Fokker D VIII Startup and Takoff YouTube Old Rhinebeck Aerodrome Sholom August 4 2019 Event occurs at 0 12 to 2 00 Archived from the original on August 13 2021 Retrieved August 13 2021 a href Template Cite AV media html title Template Cite AV media cite AV media a CS1 maint bot original URL status unknown link Gnome Monosoupape Type N Rotary Retrieved on 18 February 2009 Setright IJK 1971 The Power to Fly The Development of the Piston Engine in Aviation Allen and Unwin p 27 ISBN 978 0043380413 Vivian E Charles 2004 A History of Aeronautics Kessinger Publishing p 255 ISBN 1419101560 New England Air Museum McCutcheon Kimble D Gnome Monosoupape Type N Rotary PDF Aircraft Engine Historical Society Archived from the original PDF on 2008 07 06 Retrieved 2008 05 01 Bibliography edit Lumsden Alec British Piston Engines and their Aircraft Marlborough Wiltshire Airlife Publishing 2003 ISBN 1 85310 294 6 External links edit nbsp Wikimedia Commons has media related to Gnome Monosoupape Rattling of a Gnome engine Ground run of a rare 100 hp Monosoupape in Australia YouTube video of 100 hp Gnome Monosoupape demonstration Modern reproduction Fokker D VIII powered with 160 hp Gnome Monosoupape New Zealand built 21st century reproduction Type 9B 2 100 hp Monosoupape running Classic Aero Machining Service CAMS Reproduction Gnome Type 9B 2 Monosoupape reproduction engine development video Computer video of how the 100 CV Type 9B 2 Monosooupape Goes Together Koz Aero s Look at the Gnome 9N Monosoupape Article Retrieved from https en wikipedia org w index php title Gnome Monosoupape amp oldid 1152701579, wikipedia, wiki, book, books, library,

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