Istres is a commune in southern France, some 60 km northwest of Marseille. It is in the Provence-Alpes-Côte d'Azur region, in the Bouches-du-Rhône department, of which it is a subprefecture. Istres is adjacent to the étang de l'Olivier lagoon, it is located some 60 km north-west of Marseille, 20 km south-west of Salon-de-Provence, 10 km north of Martigues and 45 km south-east of Arles. Istres is adjacent to the plaine de la Crau and the Camargue national park; the city has numerous sports facilities and 102 clubs. Each year a race is organized around the Etang de l'Olivier. Many runners participate; the town's main football club is FC Istres. Istres is the home of the Le Tubé Air Base; this air base was one of 3 utilized by NASA as a contingency landing site for the Space Shuttle in the case of a Transoceanic Abort Landing. Istres shared this responsibility with Zaragoza and Moron, Spain. Istres has a Mediterranean climate characterised by hot, dry summers. January and February are the coldest months, averaging temperatures of around 7 °C.
July and August are the hottest months. The mean summer temperature is around 24 °C with an average maximum temperature around 32 °C; the amount of precipitation is around 566 mm per year. The Mistral, a cold and violent wind, blows through the city in winter and spring. Communes of the Bouches-du-Rhône department FC Istres INSEE Official website Satellite view with Wikimapia
A propfan called an open rotor engine, unducted fan, or ultra high-bypass turbofan, is a type of aircraft engine related in concept to both the turboprop and turbofan, but distinct from both. The design is intended to offer the speed and performance of a turbofan, with the fuel economy of a turboprop. A propfan is designed with a large number of short twisted blades, similar to a turbofan's bypass compressor. For this reason, the propfan has been variously described as an "unducted fan" or an "ultra-high-bypass turbofan." The European Aviation Safety Agency defines it as "A turbine engine featuring contra-rotating fan stages not enclosed within a casing." The engine uses a gas turbine to drive an unshrouded contra-rotating propeller like a turboprop, but the design of the propeller itself is more coupled to the turbine design and the two are certified as a single unit. United Technologies describe it as "a small diameter loaded multiple bladed variable pitch propulsor having swept blades with thin advanced airfoil sections, integrated with a nacelle contoured to retard the airflow through the blades thereby reducing compressibility losses and designed to operate with a turbine engine and using a single stage reduction gear resulting in high performance."
One of the earliest propfans was the 4,710 lbf Metrovick F.5, which featured twin contra-rotating fans at the rear of the engine and, first run in 1946. The propfan concept was first revealed by Carl Rohrbach and Bruce Metzger of the Hamilton Standard Division of United Technologies in 1975 and was patented by Rohrbach and Robert Cornell of Hamilton Standard in 1979. Work by General Electric on similar propulsors was done under the name unducted fan, a modified turbofan engine, with the fan placed outside the engine nacelle on the same axis as the compressor blades. Hamilton Standard developed the propfan concept in the early 1970s. Numerous design variations of the propfan were tested by Hamilton Standard, in conjunction with NASA in this decade; this testing led to the Propfan Test Assessment program, where Lockheed-Georgia proposed modifying a Gulfstream II to act as in-flight testbed for the propfan concept, while McDonnell Douglas proposed modifying a DC-9 for the same purpose. NASA chose the Lockheed proposal, where the aircraft had a nacelle added to the left wing, containing a 6,000 horsepower Allison 570 turboprop engine, powering a 9-foot diameter Hamilton Standard SR-7 propfan.
The aircraft, so configured, first flew in March 1987. After an extensive test program, the modifications were removed from the aircraft. General Electric's GE36 Unducted Fan was a variation on the original propfan concept, appears similar to a pusher configuration piston engine. GE's UDF had a novel direct-drive arrangement, where the reduction gearbox was replaced by a low-speed seven-stage free turbine. One set of turbine rotors drove the forward set of propellers, while the rear set was driven by the other set of rotors which rotated in the opposite direction; the turbine had 14 blade rows with seven stages. Each stage was a pair of contra-rotating rows. Airframers, wary of issue-prone gearboxes since the 1950s, liked GE's gearless version of the propfan: Boeing intended to offer GE's pusher UDF engine on the 7J7 platform, McDonnell Douglas was going to do on their MD-94X airliner; the GE36 was first flight tested mounted on the #3 engine station of a Boeing 727-100 in 1986. The GE36 UDF for the 7J7 was planned to have a thrust of 25,000 pounds-force, but GE claimed that in general its UDF concept could cover a thrust range of 9,000 to 75,000 lbf, so a UDF engine could match or surpass the thrust of the CF6, GE's family of widebody engines at that time.
McDonnell Douglas developed a proof-of-concept aircraft by modifying its company-owned MD-80, suited for propfans due to its aft fuselage-mounted engines, in preparation for the possible propfan-powered MD-91 and MD-92 derivatives and a possible MD-94X clean-sheet aircraft. They removed the JT8D turbofan engine from the left side of the fuselage and replaced it with the GE36. A number of test flights were conducted out of Mojave, which proved the airworthiness, aerodynamic characteristics, noise signature of the design. Following the initial tests, a first-class cabin was installed inside the aft fuselage and airline executives were offered the opportunity to experience the UDF-powered aircraft first-hand; the test and marketing flights of the GE-outfitted demonstrator aircraft concluded in 1988, exhibiting a 30% reduction in fuel consumption over turbo-fan powered MD-80, full Stage III noise compliance, low levels of interior noise/vibration. McDonnell Douglas successfully flight tested the 578-DX propfan, an engine collaboration between Allison and Pratt & Whitney, on the MD-80.
Unlike the competing GE36 UDF, the 578-DX was conventional, having a reduction gearbox between the LP turbine and the propfan blades. Due to jet fuel price drops and shifting marketing priorities, Douglas shelved the program the following year. Aside from the aircraft mentioned above, there were several other announcements of future propfan-powered airliners, such as: The Boeing 747-500, a propfan-powered, rewinged stretch of Boeing's jumbo jet that would carry 500 passengers up to 8,700 nautical miles at a higher speed than its previous variants The MPC-75, an 80-seat, Mach 0.76 cruise speed, 1,500 nmi range regional aircraft conceived by Germany's Messerschmitt-Bö
CFM International CFM56
The CFM International CFM56 series is a French-American family of high-bypass turbofan aircraft engines made by CFM International, with a thrust range of 18,500 to 34,000 pounds-force. CFMI is a 50–50 joint-owned company of Safran Aircraft Engines of France, GE Aviation of the United States. Both companies are responsible for producing components and each has its own final assembly line. GE produces the high-pressure compressor and high-pressure turbine, Safran manufactures the fan, gearbox and the low-pressure turbine, some components are made by Avio of Italy; the engines are assembled by GE in Evendale, by Safran in Villaroche, France. The completed engines are marketed by CFMI. Despite initial export restrictions, it is one of the most common turbofan aircraft engines in the world, in four major variants; the CFM56 first ran in 1974. In April 1979, the joint venture had not received a single order in five years and was two weeks away from being dissolved; the program was saved when Delta Air Lines, United Airlines, Flying Tigers chose the CFM56 to re-engine their DC-8s and shortly thereafter it was chosen to re-engine the KC-135 Stratotanker fleet of the U.
S. Air Force – still its biggest customer; the first engines entered service in 1982. Several fan blade failure incidents were experienced during the CFM56's early service, including one failure, a cause of the Kegworth air disaster, some engine variants experienced problems caused by flight through rain and hail. Both these issues were resolved with engine modifications. Research into the next generation of commercial jet engines, high-bypass ratio turbofans in the "10-ton" thrust class, began in the late 1960s. Snecma, who had built military engines until was the first company to seek entrance into the market by searching for a partner with commercial experience to design and build an engine in this class, they considered Pratt & Whitney, Rolls-Royce, GE Aviation as potential partners, after two company executives, Gerhard Neumann from GE and René Ravaud from Snecma, introduced themselves at the 1971 Paris Air Show a decision was made. The two companies saw mutual benefit in the collaboration and met several more times, fleshing out the basics of the joint project.
At the time, Pratt & Whitney dominated the commercial market. GE needed an engine in this market class, Snecma had previous experience of working with them, collaborating on the production of the CF6-50 turbofan for the Airbus A300. Pratt & Whitney was considering upgrading their JT8D to compete in the same class as the CFM56 as a sole venture, while Rolls-Royce dealt with financial issues that precluded them from starting new projects. A major reason for GE's interest in the collaboration, rather than building a 10-ton engine on their own, was that the Snecma project was the only source of development funds for an engine in this class at this particular time. GE was considering only contributing technology from its CF6 engine rather than its much more advanced F101 engine, developed for the B-1 Lancer supersonic bomber; the company was faced with a dilemma when the United States Air Force announced its Advanced Medium STOL Transport project in 1972 which included funding for the development of a 10-ton engine – either to build a "limited" technology 10-ton engine with Snecma, or a similar engine with "advanced" technology on their own.
Concerned that the company would be left with only the "limited" engine in its portfolio if it did not win the Air Force contract, GE decided to apply for an export license for the F101 core technology. GE applied for the export license in 1972 as their primary contribution to the 10-ton engine project; the United States Department of State's Office of Munitions Control recommended the rejection of the application on national security grounds. The official decision was made in a National Security Decision Memorandum signed by the National Security Advisor Henry Kissinger on 19 September 1972. While national security concerns were cited as the grounds for rejection, politics played an important role as well; the project, the export issue associated with it, was considered so important that French President Georges Pompidou appealed directly to U. S. President Richard Nixon in 1971 to approve the deal, Henry Kissinger brought the issue up with President Pompidou in a 1972 meeting. GE argued at the highest levels that having half of the market was better than having none of it, which they believed would happen if Snecma pursued the engine on their own without GE's contribution.
Nixon administration officials feared that this project could be the beginning of the end of American aerospace leadership. There was speculation that the rejection may have been, in part, retaliation for French involvement in convincing the Swiss not to purchase American-made LTV A-7 Corsair II aircraft, competing against a French design, the Dassault Milan. In the end, the Swiss did not purchase either aircraft, opting for the Northrop F-5E Tiger II instead. Despite the export license being rejected, both the French and GE continued to push the Nixon Administration for permission to export the F101 technology. Efforts continued throughout the months following the reject
A launch vehicle or carrier rocket is a rocket used to carry a payload from Earth's surface through outer space, either to another surface point, or into space. A launch system includes the launch vehicle, launch pad, vehicle assembly and fuelling systems, range safety, other related infrastructure. Suborbital launch vehicles include ballistic missiles, sounding rockets, various crewed systems designed for space tourism or high-speed transport. Orbital or escape launch vehicles must be much more powerful and incorporate two to four rocket stages to provide sufficient delta-v performance. Various rocket fuels are used, including solid rocket boosters and cryogenic fuels fed to rocket engines. Most launch vehicles are expendable i.e. used only once and destroyed or abandoned during the flight. Attempts to reduce per-launch costs have led to reusable launch systems, in which part of the launch vehicle is recovered and reused for another flight. Multiple classes of launch vehicle exist for use with differing launch sites, payload mass, target orbits, price points, etc.
Numerous countries have sought to develop indigenous launch vehicles for use in national space programs. Expendable launch vehicles are designed for one-time use, they separate from their payload and disintegrate during atmospheric reentry. In contrast, reusable launch vehicles are designed to be launched again; the Space Shuttle was a part of a launch vehicle with components used for multiple orbital spaceflights. SpaceX has developed a reusable rocket launching system to bring back a part—the first stage—of their Falcon 9 and launch it again, With B1046 having flown a total of three flights making it the most flown orbital class booster, Falcon Heavy launch vehicles. A reusable VTVL design is planned for all parts of the ITS launch vehicle; the low-altitude flight test program of an experimental technology-demonstrator launch vehicle began in 2012, with more extensive high-altitude over-water flight testing planned to begin in mid-2013, continue on each subsequent Falcon 9 flight. Non-rocket spacelaunch alternatives are progressing.
In June 2017, Stratolaunch Systems began ground testing the carrier aircraft component of its air launch to orbit system. The Stratolaunch is the world's largest aircraft, weighing 500,000 pounds and composed of twin fuselages with an overall wingspan of 385 feet; the Spanish company Zero 2 Infinity is developing another launch system concept, the Bloostar, a balloon-borne launcher based on rockoon technology. Launch vehicles are classified by the amount of mass they can carry into a particular orbit. For example, a Proton rocket can lift 22,000 kilograms into low Earth orbit. Launch vehicles are characterized by their number of stages. Rockets with as many as five stages have been launched, there have been designs for several single-stage-to-orbit vehicles. Additionally, launch vehicles are often supplied with boosters supplying high early thrust burning with other engines. Boosters allow the remaining engines to be smaller, reducing the burnout mass of stages to allow larger payloads. Other reported characteristics of launch vehicles are the launching nation or space agency and the company or consortium manufacturing and launching the vehicle.
For example, the European Space Agency is responsible for the Ariane V, the United Launch Alliance manufactures and launches the Delta IV and Atlas V rockets. Many launch vehicles are considered part of a historical line of vehicles of the same or similar name. Land: spaceport and fixed missile silo for converted ICBMs Sea: fixed platform, mobile platform, submarine for converted SLBMs Air: aircraft, balloon, JP Aerospace Orbital Ascender, proposal for permanent Buoyant space port. There are many ways to classify the sizes of launch vehicles; the US civilian space agency, NASA, uses a classification scheme, articulated by the Augustine Commission created to review plans for replacing the Space Shuttle: A sounding rocket, used to study the atmosphere or perform brief experiments, is only capable of sub-orbital spaceflight and cannot reach orbit. A small-lift launch vehicle is capable of lifting up to 2,000 kg of payload into low Earth orbit. A medium-lift launch vehicle is capable of lifting 2,000 to 20,000 kg of payload into LEO.
A heavy-lift launch vehicle is capable of lifting 20,000 to 50,000 kg of payload into LEO. A super-heavy lift vehicle is capable of lifting more than 50,000 kg of payload into LEO; the leading European launch service provider, Arianespace uses the "heavy-lift" designation for its >20,000 kg -to-LEO Ariane 5 launch vehicle and "medium-lift" for its array of launch vehicles that lift 2,000 to 20,000 kg to LEO, including the Starsem/Arianespace Soyuz ST and pre-1999 versions of the Ariane 5. It refers to its 1,500 kg to LEO Vega launch vehicle as "light lift". Suborbital launch vehicles are not capable of taking their payloads to the minimum horizontal speed necessary to achieve low Earth orbit with a perigee less than the Earth's mean radius, which speed is about 7,800 m/s. Sounding rockets have long been used for brief, inexpensive unmanne
Vulcain is a family of European first stage rocket engines for Ariane 5 and the future Ariane 6. Its development began in 1988 and the first flight was completed in 1996; the updated version of the engine, Vulcain 2, was first flown in 2005. Both members of the family use liquid oxygen/liquid hydrogen cryogenic fuel; the new version under development for Ariane 6 will be called Vulcain 2.1. The development of Vulcain, carried out by a European partnership, began in 1988 with the Ariane 5 rocket program, it first flew in 1996 powering the ill-fated flight 501 without being the cause of the disaster, had its first successful flight in 1997. In 2002 the upgraded Vulcain 2 with 20% more thrust first flew on flight 517, although a problem with the engine turned the flight into a failure; the cause was due to flight loads being much higher than expected. Subsequently, the nozzle was redesigned to include mechanical reinforcement of the structure and improvement of the thermal situation of the tube wall through enhancing hydrogen coolant flow as well as applying a thermal barrier coating to the flame-facing side of the coolant tubes.
The first successful flight of the Vulcain 2 occurred in 2005 on flight 521. On 17 June 2007 Volvo Aero announced that in spring of 2008 it expected to hot-fire test a Vulcain 2 nozzle manufactured with a new "sandwich" technology; the development of the future version for Ariane 6, Vulcain 2.1, began in 2014. First flight-configuration engine nozzle was delivered in June 2017, reducing parts count by 90%, cost by 40% and production time by 30% comparing to the engine nozzle of Vulcain 2; the Vulcain is a gas-generator cycle rocket engine fed with cryogenic liquid oxygen and liquid hydrogen. It features regenerative cooling through a tube wall design, the Vulcain 2 introduced a particular film cooling for the lower part of the nozzle, where exhaust gas from the turbine is re-injected in the engine, it powers the first stage of the Ariane 5 launcher, the EPC and provide 8% of the total lift-off thrust. The engine operating time is 600 s in both configurations. 3 m tall and 1.76 m in diameter, the engine weighs 1686 kg and provides 137 t of thrust in its latest version.
The oxygen turbopump rotates at 13600 rpm with a power of 3 MW while the hydrogen turbopump rotates at 34000 rpm with 12 MW of power. The total mass flow rate is 235 kg/s; the main contractor for the Vulcain engines is Snecma Moteurs, which provides the liquid hydrogen turbopump. The liquid oxygen turbopump is the responsibility of Avio, the gas turbines that power the turbopumps and the nozzle are developed by GKN. Comparison of orbital rocket engines Spacecraft propulsion Timeline of hydrogen technologies RS-68 J-2X SSME RD-0120 Arianespace – Ariane 5: Cryogenic Main Stage and Solid Boosters Ariane 5 ECA and Snecma – Snecma Moteurs: Vulcain 2 engine proves its mettle "LH2 Turbine". – Volvo Aero "LOX Turbine". – Volvo Aero "Development of the turbines for the Vulcain 2 turbopumps". Archived from the original on 2007-09-30. – Volvo Aero "High cycle fatigue of Vulcain 2 LOx turbine blades". Archived from the original on 2007-09-27. – Volvo Aero "An efficient concept design process". Archived from the original on 2007-09-27.
– Volvo Aero "Vulcain 2 nozzle". – Volvo Aero EADS N. V. – EADS welcomes contract signature for 30 Ariane 5 launchers at ILA 2004 in Berlin Three billion Euros contract for 30 Ariane 5 launchers – EADS Astrium
General Electric GE90
The General Electric GE90 is a family of high-bypass turbofan aircraft engines built by GE Aviation for the Boeing 777, with thrust ratings from 81,000 to 115,000 lbf. It entered service with British Airways in November 1995, it is one of three options for the 777-200, -200ER, -300 versions, the exclusive engine of the -200LR, -300ER, 777F. It is the most powerful jet engine, its 6 in wider fan successor, the 105,000 lbf GE9X, is expected to power the Boeing 777X from 2019. The GE90 was developed from the NASA 1970s Energy Efficient Engine. GE's GE36 UDF was meant to replace the CFM International CFM56 high-bypass turbofan, noncompetitive against the rival IAE V2500. However, when the V2500 ran into technical problems, sales of the CFM56 took off. GE was not interested in having the GE36 cannibalize the CFM56, while "the UDF could be made reliable by earlier standards, turbofans were getting much, much better than that." However, GE integrated the UDF’s blade technology directly into the GE90. The GE90 engine was launched in 1990.
GE Aviation teamed with IHI and Avio for the program. The GE90 was only one of three 777 options and GE Aviation then-CEO Brian H. Rowe would have paid for the development of putting it on an A330, but Airbus' strategy for long-haul was the four-engine A340, missing the market favouring twins; the GE90's 10-stage high-pressure compressor develops an industry record pressure ratio of 23:1 and is driven by a 2-stage, air-cooled, HP turbine. A 3-stage low-pressure compressor, situated directly behind the fan, supercharges the core; the fan/LPC is driven by a 6-stage low-pressure turbine. The higher-thrust variants, GE90-110B1 and -115B, have a different architecture from the earlier GE90 versions, with one stage removed from the HP compressor and an extra stage added to the LP compressor. A net increase in core flow was achieved. General Electric performed a similar re-staging exercise when they upgraded the CF6 from the -6 to the higher-thrust -50. However, this thrust growth route is expensive, since all the downstream components must be larger for flow capacity.
The fan is an advanced, larger diameter unit made from composite materials and is the first production engine to feature swept rotor blades. Its nacelle has a maximum diameter of 166 in; as one of the three available engines for the new Boeing 777, the GE90 was an all-new $2 billion design meant to handle transoceanic routes, in contrast to the offerings from Pratt & Whitney and Rolls-Royce which were modifications of existing engines. The first General Electric-powered Boeing 777 was delivered to British Airways on November 12, 1995; the aircraft, with two GE90-77Bs, entered service five days later. Initial service was affected by gearbox bearing wear concerns, which caused the airline to temporarily withdraw its 777 fleet from transatlantic service in 1997. British Airways' aircraft returned to full service that year. Problems with GE90 development and testing caused delays in Federal Aviation Administration certification. In addition the GE90's increased output was not yet put to use by airlines and it was the heaviest engine of the three available choices, making it the least popular option while Rolls-Royce held the top spot.
British Airways soon replaced the GE90 with Rolls-Royce engines on their 777s. For Boeing's second-generation 777 long-range versions, greater thrust was needed to meet the specifications. General Electric and Pratt & Whitney insisted on a winner-take-all contract due to the $500 million investment in engine modifications needed to meet the requirements. GE received sole engine supplier status for the higher-thrust engine variants for the 777-200LR, -300ER, 777F; the higher-output GE90-110B1 and -115B engines, in combination with the second-generation 777 variants -200LR and -300ER, has been a primary driver of the twinjet's sales past the rival A330/340 series. Using two engines produces a typical operating cost advantage of around 8–9% for the -300ER over the A340-600; the 777-300ER has been seen as a 747-400 replacement amid rising fuel prices given its 20% fuel burn advantage. Until passed by its derivative, the GE9X, the GE90 series held the title of the largest engines in aviation history.
The fan diameter of the original series being 123 in, the largest variant GE90-115B has a fan diameter of 128 in. As a result GE90 engines can only be air freighted in assembled form by outsize cargo aircraft such as the Antonov An-124, presenting unique problems if, due to emergency diversions, a 777 were stranded in a place without the proper spare parts. If the fan is removed from the core the engines may be shipped on a 747 Freighter; the -94B for the -200ER is being retrofitted with some of the first FAA-approved 3D-printed components. It has an in-flight shutdown rate of one per million engine flight-hours, it accumulated 50 million flight hours in 20 years. The GE90-115B is powerful enough to operate GE's Boeing 747 testbed on its own power, an attribute demonstrated during a flight test. According to the Guinness Book of Records, at 127,900 lbf, the engine holds the record for the highest thrust; this thrust record was accomplished inadvertently as part of a one-hour, triple-red-line engine stress test.
To accommodate the increase in torsional stresses, a new steel alloy, GE1014 was created and machined to extreme tolerances. The new record was set during testing of a GE90-115B development engine at GE Aviations' Peebles Test Operation, an outdoor test complex outside Peebles, Ohio, it eclipsed the engine's pre
Gnome et Rhône
Gnome et Rhône was a major French aircraft engine manufacturer. Between 1914 and 1918 they produced 25,000 of their 9-cylinder Delta and Le Rhône 110 hp rotary designs, while another 75,000 were produced by various licensees; these engines powered the majority of aircraft in the first half of the war, both Allied designs as well as German examples produced by Motorenfabrik Oberursel. In the post-war era they started a new design series based on the Bristol Jupiter, but evolving into the excellent 1,000 hp-class Gnome-Rhône 14K Mistral Major radial, licensed and used around the world during World War II, they were a major supplier of engines to the German Luftwaffe, producing both their own designs as well as German ones under licence. Their factories were the target of accurate bombing, knocking them out of the war; the company was nationalized as a part of Snecma in 1949, but the brand lived on for a time as the manufacturer of Gnome et Rhône motorcycles and Gnome et Rhône bicycles. In 1895 the 26-year-old French engineer Louis Seguin bought a license for the Gnom gas engine from the German firm Motorenfabrik Oberursel.
Sold under the French translation, the Gnome was a single-cylinder stationary engine of about 4 hp that ran on kerosene intended to be used in industrial applications. The Gnome used a unique valve system with only one rod-operated exhaust valve, a "hidden" intake valve located on the cylinder head. On 6 June 1905 Louis Seguin and his brother Laurent formed the Société Des Moteurs Gnome to produce automobile engines, they soon started development of one of the first purpose-designed aircraft engines, combining several Gnome cylinders into a rotary engine. The design emerged in the spring of 1909 as the 7-cylinder rotary Gnome Omega, delivering 50 hp from 75 kg. More than 1,700 of these engines would be built in France, along with license-built models in Germany, Britain, the United States and Russia; the Gnome powered Henry Farman's Farman III aircraft to take the world records for distance and endurance, as well as powering the first aircraft to break 100 km/h, as well as the first seaplane to fly in 1910, powering France to become the leading country in aviation at the time.
Léon Lemartin and Jules Védrines were two young engineers who participated in the design and implementation of the Omega, in the milieu of the pioneering days of flight they both went on to become successful pilots. All of the Gnomes were known for their unique solutions to getting fuel to the top of the piston without using piping. Early models used two valves, one in the cylinder head and a second embedded in the piston itself, counterweighted to open at the end of the stroke. Without any springs or pushrods, the valve would pop open on the downstroke, allowing fuel to be drawn into the cylinder from the crankcase area, it was very difficult to service, requiring the cylinder to be disassembled. In order to improve reliability and maintenance models used the Monosoupape system instead, using a single exhaust valve at the top of the cylinder and using a series of ports to allow the fuel mixture into the top of the cylinder when the piston had moved down in the cylinder past the ports; the basic Gnome design was delivered in a series of larger engines.
The Gnome Lambda of 1911 was a larger 80 hp version of the Omega, followed by the 9-cylinder 100 hp Gnome Delta in 1914. Gnome tried a 14-cylinder two-row version, the Double Lambda of 160 hp, but this saw little use though it was copied by Oberursel as the U. III in Germany, used in a few early Fokker fighter designs without success. To deliver more power with the advent of high-power inline engines late in the war, a new nine-cylinder Monosoupape design was delivered in 1918 as the Type-N, delivering 160 hp; this design saw use on the little-known but excellent Nieuport 28. Another French engineer, Louis Verdet, designed his own small rotary engine in 1910 which did not see much use. In 1912 he delivered the 7C, which developed 70 hp from 90 kg; this proved much more popular and he formed Société des Moteurs Le Rhône that year. He soon followed the 7C with a nine-cylinder design delivering 80 hp. Compared to the Gnome's, the Le Rhône was more "conventional", using copper intake manifold pipes to bring the fuel to the top of each engine cylinder, along with intake and exhaust valves.
Like Gnome, the Le Rhône designs were licensed, in this case the 110 hp Le Rhone 9J was produced in Germany bu Oberursel as their Ur. II model as designated by IdFlieg, in the United States. After several years of fierce competition, Gnome and Le Rhône decided to merge. Negotiations started in 1914, on 12 January 1915 Gnome bought out Le Rhône to form Société des Moteurs Gnome et Rhône. Developments of the 9C continued to be their primary product, improving in power to about 110 hp in the Le Rhône 9J by the end of the war; the 9-series was the primary engine for most early-war designs both in French and British service as well as in Germany where somewhat Oberursel had taken out a license just before the war. Oberursel's engine based on the Gnome designs were prefixed with a U, while those based on the Le Rhône a Ur. With the end of the war the company diversified, using their factories to produce chassis and engines for the Rol