Sunday, 16 October 2016

Comac C919


The Comac C919 is a planned family of 158–174 seat narrow-bodytwin-engine jet airliners to be built by the Commercial Aircraft Corporation of China (Comac). It will be the largest commercial airliner designed and built in China since the defunct Shanghai Y-10. Its first flight is expected to take place in 2016, with first deliveries scheduled for late 2018. Roll-out ceremony was held in Shanghai on 2 November 2015.

Image: kosnews24gr

The C919 forms part of China's long-term goal to break Airbus and Boeing's duopoly, and is intended to compete against Airbus A320neoBoeing 737 MAXIrkut MC-21, and other next-generation single-aisle airliners.

Development

Comac applied for a type certificate for the aircraft from the Civil Aviation Authority of China on 28 October 2010. The company plans to conduct the first flight of the C919 in 2017, with deliveries beginning in 2018, whereas Marwan Lahoud, Chief Strategy & Marketing Officer of Airbus Group, assumes a competition outside China around 2020.

The assembly of the COMAC C919 takes place in Shanghai. – Image: modernairliners

In June 2011 COMAC and Irish low-cost airline Ryanair signed an agreement to co-operate on the development of the C919 On 24 November 2011, Comac announced the completion of the joint definition phase, marking the end of the preliminary design phase for the C919. The company said it planned to cut the first metal for the aircraft in December 2011, with estimated completion of the detailed design phase in 2012.

C919's advanced aerodynamics were engineered with the help of the Tianhe-2 supercomputer. With an estimated development cost of $8.3 billion, Comac planned to produce 5–10 planes per year in 2016 and 2017, subsequently ramping up to 150 C919s. The company intends to manufacture up to 2,300 aircraft of that type.

In 2014 delivery was yet again delayed by technology and supplier problems, this time to 2018. Comac rolled out its first C919 aircraft off the assembly line in September 2015 with no engines installed.

On 2 November 2015, Comac rolled out its first C919 aircraft.

China's Comac C919 plane to Be Tested in 2017: Here


Excerpt

The first test flight of China’s Comac C919 plane will most likely take place in the first quarter of 2017, Chinese media report.


BEIJING (Sputnik) – The test flight could take place as early as February, although the exact date has not been announced yet, People’s Daily said on Saturday citing the Commercial Aircraft Corporation of China (Comac).

China-made C919 to make maiden flight soon : Here

Excerpt

The C919, the first large passenger aircraft designed and built by China passed the last expert assessment on Tuesday, its manufacturer announced.

The aircraft was given the go-ahead to begin a series of high-speed taxiing tests, the last step before its maiden flight. The process usually takes one to two months.

According to Shanghai-based Commercial Aircraft Corp. of China (COMAC), 25 experts from Chinese research institutes, civil aviation administration, and domestic jet makers formed Tuesday's assessment panel. They reviewed the preparedness of both the aircraft and ground services for the maiden flight.


C919 makes maiden flight: Here


Excerpt

The Comac C919 narrowbody lifted off from Shanghai Pudong International airport's fourth runway at 14:00 local time, marking its maiden sortie seven years into its development.

Onboard aircraft B-001A as it took off on an overcast Shanghai day are a team of five. In the cockpit are flight test captain Cai Jun, co-pilot Wuxi and flight observer Qian Jun. In the cabin are two flight test engineers – Zhang Da Wei and Ma Fei.

The first flight will lasts about 1.5 hours, during which the CFM International Leap-1C-powered aircraft's landing gear will not be retracted, Comac's flight test manager You Li Yan told reporters in Shanghai. The aircraft is expected to reach an altitude of 10,000ft.

China's COMAC says C919 jet completes 2nd test flight: Here

C919 performed 2nd flight test this morning at Pudong airport, which lasted 2h 46m. Photos by . Source: dafeng cao

Excerpt

China’s domestically developed C919 passenger jet completed its second test flight on Thursday, the jet’s maker said, but there were questions about its duration and on the near five-month gap between the two test flights.

The narrow-body aircraft, which will compete with Boeing’s 737 and the Airbus A320, is a symbol of China’s ambitions to muscle into a global jet market estimated to be worth $2 trillion over the next 20 years. It first flew on May 5 after numerous delays.


“The plane has made a smooth return,” a spokesman for its manufacturer, Commercial Aircraft Corp of China (COMAC) [CMAFC.UL], told Reuters.

Design

Design and assembly of the aircraft is done in Shanghai, using foreign-made jet engines and avionics. However, China has expressed its desire to produce a domestically made engine for the C919.

The center wing box, outer wing box, wing panels, flaps and ailerons are planned to be built in Xi'an, China. The center fuselage sections are planned to be built in Hongdu, China. The airframe will be made largely of aluminium alloy. The center wing box was originally intended to use of carbon fiber composites, but the design was changed to an aluminum design to reduce program complications.

Center wing box – Image: comac
The center fuselage section – Image: Romain Guillot

CFM International will supply a version of the LEAP engine, the LEAP-1C, to power the aircraft The engine's nacellethrust reverser and exhaust system will be provided by Nexcelle, with such features as an advanced inlet configuration, the extensive use of composites and acoustic treatment and an electrically operated thrust reverser. Michelin will supply Air X radial tyres.



LEAP-1C

Figure 1. LEAP-1 engine cut through showing the main areas of interest. Source: CFM.

No 1 marks the fan and fan case. GE is the world leader in CFRP-based fans (first with GE90) and fan cases (first with GEnx). LEAP is now taking this technology further. The GE90 and GEnx blades are hand-laid up from CFRP prepreg cloth. Snecma, which has responsibility for the fan and low pressure parts in CFM, has formed a joint venture, Albany Engineered Composites Inc. (AEC, Rochester, N.H.) with one of US high tech weaving companies, Albany International. AEC has the technology to weave the Carbon fibers into a 3D mesh which when placed in a form get soaked in injected resin.

Figure 2. Albany Engineering Composites, AEC, resin infusion fan blade form with the interlocked weaved carbon fiber in place. Source: AEC

With this technique, fibers can be woven in an interlocking manner eliminating any risk of delamination associated with the discrete layers of prepreg in conventional blade layup. The technique can also be more automated, necessary for the high volumes that the LEAP will be produced in.

This process also gives very exact control of the blades properties like directional stiffness of the different parts and we understand that Snecma is using this to have the blades form themselves according to their working condition. A modern fan is a very advanced piece aerodynamically. Its tips are supersonic, the middle part has transonic aerodynamics and the inner part has subsonic aero. This requires different aerodynamic forms, from thin and pointy to blunt and round. In all 3D woven resin infused blade ensures a very exact blade with high efficiency and low weight. AEC is also producing the fan case in the same way, first forming the weave and then infusing the resin.

Right after the fan come the booster compressor. As it sits on the same diameter as the fan’s inner part it has subsonic aerodynamics and a low speed through the air. The pressure gain is therefore low, on the level of the fans average pressure ratio of around 1.4-1.5. Conversion efficiency, shaft hp to pressure gain, can still be as high as the fans efficiency using today’s advanced 3D aerodynamics, above 90%.

No 2 denotes the variable bleed ports on the outer part of the swan neck duct between booster and compressor. The fan will ingest debris like sand from the runway. It is important to keep that away from the fine dimension of gaps and seals in the core. CFM uses several techniques to ensure this:

–  the spinner form throws most debris past the core entry, into the bypass.
–  The small particles that do enter the core swan neck will then slide on the outer wall of the duct due to its curvature where the engine control computer, the FADEC, can angle the handling bleed doors slightly open to catch the particles that got ingested and route these to the bypass duct. This technique has been proven on the GE90 operating in sandy environments.

No3. Snecma is also responsible for the gearbox with accessories. It is mounted on the fan case to ease service access and slung to the side to maximize ground clearance.

No 4. The passing point of the responsibility in the core from Snecma to GE Aviation, where the booster swan neck leads into the High Pressure Compressor, HPC.

No 5. The high pressure compressor, HPC. It takes the air from a pressure raise of around 2 and raises that to above 40 before the air passes into the combustor. GE Aviation is known in the industry to be the masters of efficient high pressure rate compressors. Our simulations for cruise suggests the HPC for the MAX8 consumes around 9,500 hp to do that with a conversion efficiency (shaft energy to compressed air energy) of well above 90%. At its peak operating point it can raise the pressure 22 times, most of the time it is operating around 20 times however.

One of the effects of this high compression is that the air gets hot, at ground level and hot take-offs the HPC exit temperature can be a limiting factor. Our simulations with GasTurb suggest the HPC exit would be at around 700°C or 1,200°F. The last stages of the HPC is therefore made with heat resistant nickel based alloys whereas the early stages are made of Titanium. They can be machined in on piece (nickel based alloys are not easy to machine), so-called BLISKs, giving both aerodynamic (leakage) as well as manufacturing advantages.

At this point it can be instructive to understand that most values in a turbofan engine vary with the demanded thrust. Figure 3 is showing a diagram from a GasTurb simulation of the LEAP-1B at average cruise height. It shows what happens with specific fuel consumption (SFC), overall pressure ratio (OPR) and by-pass ratio (BPR) when the engine goes from en-route climb (5,300 lbf) to cruise (4,500 lbf) to flight idle (probably around 1,000 lbf).

Figure 3. Simulation of LEAP-1B working line with GasTurb12. Source: GasTurb and Leeham Co.

The diagram shows several interesting aspects of turbofan design:

TSFC: this varies with every thrust setting of the engine, important is that the TSFC “bucket” has its minimum at cruise thrust (between 4,000-5,000 lbf).

OPR: The overall pressure ratio of an engine is a function of its rpm, high thrust = high rpm = high OPR. The important area is once again cruise where OPR would be around 40, a good value and one of the corner-stones in the high efficiency of the LEAP.

BPR: Finally the By Pass Ratio, BPR, is varying from 8.7 to 13-15 at flight idle. BPR is strongly coupled to how hard the engine is working, the higher thrust, the more air through the core (to generate shaft hp) and lower BPR. This is why higher rated members of an engine family always have lower typical BPR. The kink in the BPR is from the on-set of a handling bleed through the variable bleed ports after the booster. At low load the HPC gets to aggressively feed by the booster and therefore excess air is bleed into the bypass channel from (in our simulation) 2,200 lbf thrust. Should this not be done the HPC early stages would stall.

No6. On our journey through the engine the next station is the combustor. One of the problems with high pressure ratios in turbofans is that this creates high levels of NOx emissions. GE has developed a lean burn two-zone combustor series called TAPS to master. LEAP is using the latest incarnation of this technology, TAPS II. The TAPS combustor also has a very uniform distribution of the heat in the exit gasses to avoid hot spots in the combustor nozzle and the first high pressure turbine stage.

No 7. LEAP divides the driving of the high pressure compressor over two turbine stages instead of one for the CFM56. This is necessary as the work done in the HPC has doubled, from maximum pressure ratio 11 for the CFM56 to 22 for LEAP. To create shaft hp efficiently with the smallest core, the gasses entering the turbines shall be hot and at high pressure. State-of-the-art right now (GEnx-1B75 ) is 1,700°C or 3,150°F turbine entry temperature and about 55 in pressure raise from inlet to first turbine. As stated by CFM, LEAP has another optimization philosophy than GEnx. We have assumed around 1,550°C and a pressure rise of around 50 at the most extreme working point.

To withstand such temperatures, the turbine section requires cooling and quite a lot of it for the first stages. At the toughest operating point, which we found to be one engine out at V2 on a hot day, the turbines needs over 20% of the air produced by the compressors for cooling. This cooling air is consistently taken from the lowest compression level possible in the engine, from fan, booster, compressors and even combustor; the pressure need to be high enough to secure positive circulation in the cooling object at all conditions but not more, any more pressure and the air is hotter than needed (worse cooling result) and more engine work has been invested in creating the cooling air than necessary.

A turbofan is therefore riddled with cooling air off-takes. The CFM56 has about 10, from after the fan for nacelle and aircraft bleed air cooling to the HPT being cooled with air from the combustors peripheral airflow. The highest cooling demands are for critical flight cases like takeoff or one engine flight. For cruise, the demands are lower. It is therefore attractive to regulate the cooling air for the different load cases. Easiest is to regulate the air to the stator side but the latest airliner engines have also regulated the air to the turbine rotors. To check what regulated turbine cooling would give, we halved the turbine cooling air in our simulator, which gains the engine about 1% in TSFC.

Better still is to use materials that require very little cooling such as Ceramic Matrix Composites, CMC.  GE is a leader in the use of CMC for turbine engines. GE has deployed it in their stationary gas turbines for years and the LEAP now forms the premier for deployment of CMC in airliner engines. The application is on the outer shroud of the first high pressure turbine, Figure 4.

Figure 4. First high pressure turbine shroud which uses CMC lining elements. Source: CFM picture with Leeham Co commentary.

This is a clever choice. Should CFM hit any trouble with such an application it should not be difficult to replace it with a conventional Nickel alloy shroud. The drawback would be higher weight and perhaps more important, an increase of the cooling air flow to the shroud, but the change of the section to a conventional layout would be pretty straight forward. We don’t expect this to happen, GE has major knowledge and investments in CMC technology, but it shows how one approach new technology in a prudent way.

No 8. The Low Pressure Turbine, LPT, is the real work area of the engine. This is where the thousands of horsepower are produced to drive the fan (and the booster compressor but it only consumes a fraction of the power). At hot day sea level takeoff, the MAX 8 would ask the LPT to furnish the fan+booster with 29,000 hp. It does this work by dividing the extraction of the power in the gasses over five turbine stages with flow turning stator guide vanes in-between. It is therefore natural the LPT is a major building block of a modern turbofan and it constitutes an important part of the engine weight. The first stages operate in high temperature (around 1,000°C or 1,800°F) and are implemented in heavier nickel based rotor technologies but when the temperature sinks the last stages are made with lighter Titanium-Aluminide alloy technology.

Source: leehamnews



Dimensions of the C919 are very similar to the Airbus A320, possibly to allow for a common pallet to be used. Its fuselage will be 3.96 metres (13 feet) wide, and 4.166 metres (13 feet, 8 inches) high, producing a cross-section of 12.915 square metres (139 square feet). The wingspan will be 33.6 metres (110 feet, 3 inches), or 35.4 metres (116 feet, 3 inches) if winglets are included.


Payload will be 20.4 metric tonnes. Its cruise speed will be Mach 0.785 and it will have a maximum altitude of 12,100 metres (39,800 feet).

There will be two variants. The standard version will have a range of 4,075 km (2,200 nmi), with the extended-range version able to fly 5,555 km (2,999 nmi).


According to a film shown by Comac at the 2010 Zhuhai Airshow, the company plans to build six different models of the aircraft: a base passenger aircraft with 168 seats, as well as stretched and shrunk passenger versions,business jet and freighter models, and a type designated only as "special".


Target

The Comac C919 is intended to be a new entrant in the commercial airliner market specifically targeted at low-cost airlines. Fuel price increases are especially damaging to the low-cost flying model, leading these airlines to renew their fleets frequently. This ensures optimal fuel performance and reliability across a single-type fleet. Direct competitor Boeing 737 MAX unit cost of US$80.6–116.6 million in 2015 means that target price for this airplane should be lower. The Airbus A320neo has a wider price range of US$75.1–125.7 million. The Comac developers have not announced a price tag for each plane, although based on industry speculation current orders for 2012 could be worth more than US$26 billion. With 380 orders secured as of 2012, this results in projected average price of about US$68 million.

Honeywell Eyes $15 billion Opportunity on Comac’s C919: Here

Excerpt

Honeywell’s partnership with the Commercial Aircraft Corporation of China (Comac) C919 program represents a $15 billion opportunity for the U.S. company, its top regional aerospace official told AIN in the run-up to the Singapore Airshow.

“It’s going to be a great aircraft. If you read deeper into the aircraft, it will be very competitive with the aircraft that are flying right now,” said Briand Greer, president, Honeywell Aerospace Asia Pacific. “It’s not old, but current, technology.”

Comac’s efforts to develop a domestic aircraft to take on the market’s dominant narrow-body players, the Boeing 737 and the Airbus A320, have faced repeated setbacks. Despite delays, the arrival in November of a prototype represented new progress.


Honeywell joined the project in 2010, when Comac invited it to provide four essential components, “including flight control systems, wheels and brakes, auxiliary power units, and navigation systems,” the company said.

Some experts believe the C919 will not be competitive either technologically or commercially when it enters service given the plane's strong dependence on foreign suppliers. In particular, the engines will likely be sourced from CFM International Inc. (LEAP-1C engine), the same company that sells the CFM International CFM56 used by direct competitors. Others also say that it will most likely not be competitive given that every single commercial airline (except for City Airways which is based in Thailand) that has placed an order for the aircraft is a Chinese airline that wants to support their country's technology. This idea is reinforced because all of the Chinese airlines that have placed orders for the C919 already have either the Boeing 737 or Airbus A320 in its fleet. In 2013, state-owned newspaper Global Times complained that an Aviation Week editorial about the bleak prospects for the aircraft "maliciously disparaged the future outlook for the C919."


Honeywell: Chinese contract agreed: Here


Excerpt

Honeywell has been selected by Commercial Aircraft Corporation of China, Ltd. (COMAC) to supply its 131-9[C9C] Auxiliary Power Unit (APU) and associated equipment for the C919 single-aisle commercial airliner.


The new APU design is based on Honeywell’s highly successful 131-9 family of APUs, which have more than 51 million hours in commercial service on narrow-body aircraft like the Boeing 737 and the Airbus A320.

“Honeywell’s 131-9A is the most popular APU for single-aisle commercial aircraft in the world today,” said Honeywell Chairman and CEO Dave Cote. “Our APU has proved to be highly reliable, fuel efficient and quiet in the millions of hours of in-flight service that it has recorded to date.”



C919 Supplier Table


COMPONENT
SUPPLIER
Engines
  • Leap X1C engine supplied by CFMI, a joint venture between US based General Electric and French based SNECMA.  
  • In the long term, COMAC intends to power the C919 with the home developed AVEC CJ-1000A engine. No target date has been given yet.
Avionics
Rockwell Collins, Honeywell, CETC, GE AVIC, (General Electric joint venture with AVIC (Aviation Industry Corporation of China))
Fight Control System – Full Authority Fly by wire and advanced active control technology.
Parker, AVIC, Honeywell, MOOG
Landing Gear System
Liebherr
Hydraulic System
Parker, AVIC
Air Conditioning System
Liebherr
Electric System
Hamilton, Sundstrand, AVIC
Flight Deck and Cabin Interior
FACC, XML
APU (auxilary power unit)
Honeywell, AVIC
Fire protection
KIDDE, AVIC
Lighting System
Goodrich, AVIC, TM, Jiuzhou, Eaton

C919 Specs

The first iteration of the family of airliners planned by COMAC is the 156-174 seat C919.  This will be the smallest of the plane makers’ offerings and looks to be offered in 6 variations. It is hard to know if this encompasses the whole fleet of C919, C929 and C939.  The offerings are called: Baseline, Stretched, Freighter, Shortened, Business and Specials.


The C919 flight deck is very much along the lines of the Airbus style, with a side control joystick instead of the standard control column controlling the fly by wire system. Instrumentation is state of the art with two 15.4 inch main display screens in front of each pilot as well as a 12.5 inch side screen below the window. In addition, the C919 will be offered with the option of a HUD (Head Up Display). This is used in fighter jets where instrument data is projected onto a window in front of the pilot so he can monitor data such as airspeed, altitude and other information without having to look down. In other words his/her head remains up.

Material source: modernairliners

Orders: Here


Military application



Specifications


C919-MixedC919-All ECOC919-High Density
Flight crew2
Seating capacity156 (2-class)168 (1-class)174 (1-class)
Seat pitch base line12 passengers (97 cm (38 in)) + 144 passengers (81 cm (32 in))168 passengers (81 cm (32 in))174 passengers (76 cm (30 in))
Length38.9 metres (127 ft 7 in)
Wingspan35.8 metres (117 ft 5 in)
Wing area115 square metres (1,390 square feet)
Wing sweepback
Height11.95 metres (39 ft 2 in)
Cabin width3.9 metres (12 ft 10 in)
Cabin height2.25 metres (7 ft 5 in)
Aisle width
Seat width
Typical empty weight
Maximum take-off weight77,300 kilograms (170,400 lb) extended range
Range fully loaded4,075 km (2,200 nmi)5,555 km (2,999 nmi)
Max. operating speedMach 0.785 900 kilometres (560 mi) (extended range)
Normal cruise speed834 kilometres per hour (518 mph)
Take off run atMTOW
Service ceiling12,100 metres (39,700 ft)
Powerplants (2x)CFM International LEAP-1C Single turbofan engine
Engine thrust110,000–130,000 N (25,000–30,000 lbf)
Main material source: wikiwand

Updated Sep 28, 2017