COMAC C929 Widebody Airliner

didklmyself said:

How safe is this "memorandum of understanding"? Reading this forum, it is clear China can produce all required parts... so, why are they so invested in making deals? Certification alone cannot be the reason.

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for example, Oxygen system for C929. Chinese company successfully developed this system back in 2023, tested and passed verification as well..

put this screen-shot in google translate..


i have no idea why COMAC goes to Safran despite the fact, they have this system locally available. maybe they still want mature and Proven system.

one more thing, this is just the MOU.. and MOU don't have any legal worth/value.

Safran has deep connections in mainland. multiple facilities and production centers across many provinces. these systems mostly will come from Safran China. COMAC has long standing agreements with Safran. also France is reliable partner.

Tomboy said:

C929 specs:

282 passengers
9 seat abreast arrangement
6500 nautical mile range
247.5 ton MTOW

Compared to its competitor:
B788:

242 passengers
9 seat abreast arrangement
7300 nautical mile range
228 ton MTOW

B789:
296 passengers
9 seat abreast arrangement
7565 nautical mile range
254.7 ton MTOW


Personally, I find it odd that a design meant for service nearly 30 years later still can't be competitive to western designs even on paper. I've always heard rumors about people in the industry/higher ups being disappointed in COMAC for being overly conservative and not delivering on promises. Hopefully they make some good design changes to make C929 actually competitive against modern western offering(and the future as by 2035 Airbus might be pushing out the latest A350 iteration same with Boeing assuming they don't scew up) and not decade old designs like how C919 is right now.

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Some key points -

This is the base variant of C929. this aircraft have two more variants coming like C929-800

B-787 Dreamliner introduced in 2011-12. its a very modern machine and 787-10 range is 6330 nm with 254 ton MTOW.. 12,000+ KM range is basically the standard for widebody airliners. which is absolutely fine for C929.

C929 cabin is wider than B-787 and almost same as A350.. information is available on this thread.

China being the latecomer has certain advantages, they can apply modern manufacturing techniques and material..
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1. C929 composite material on airframe/wings would be more than B-787 and exceed 50% of total area. Note, contrary to C919 having a secondary alternative design (more composite), C929 has only one (composite) design from the conception.



2. The main load-bearing structures on C929 mainly use T800-grade carbon fiber/toughened epoxy materials, and the secondary load-bearing structures mainly use T300-grade carbon fiber/non-toughened epoxy materials.

3. C929 uses SLM to print titanium alloy wing brackets, achieving a 30% weight reduction and a 20% strength increase.
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comparison with 787-900 numbers


61.81m long, 60.12m wingspan, 17.02m high, fuselage cabin width is 5.49m and external width is 5.77m
MTOW is 254.7t
max payload 53t

so in comparison, C929 is 1m longer in total length
3m longer wingspan
MTOW is 7t lower
payload is 2.5t lower

The MTOW is lower with similar payload, so i guess is that the empty weight is lower due to structural design and composite material. And it would need to be lower to be competitive. coz its a clean-sheet design.

so C929 will be a modern/competitive machine. and sometime you don't need cutting edge product as long as you are able to manufacture/design same category class machine. means widebody airliner.
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COMAC also confirmed C939 too. but didn't share any details.

COMAC denied supersonic aircraft development now.. but who knows what tomorrow will bring. i think supersonic airliner depend on the circumstances. how things folds in coming years. so let see

didklmyself said:

How safe is this "memorandum of understanding"? Reading this forum, it is clear China can produce all required parts... so, why are they so invested in making deals? Certification alone cannot be the reason.

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A Memorandum of Understanding is just a statement that both party signed and indicate that they understands the content of a future cooperation that might lead to a contract in the future. Meaning, MoU has no binding power to force either party to sign any contract if they change their mind. And cannot be enforced in a court of law for non-performance.

A contract is different that it is enforceable, and can be sued for non-performance by one of the signature party.

In short, China and France just showed their intention to work together and nothing else.

sunnymaxi said:

Some key points -

This is the base variant of C929. this aircraft have two more variants coming like C929-800

B-787 Dreamliner introduced in 2011-12. its a very modern machine and 787-10 range is 6330 nm with 254 ton MTOW.. 12,000+ KM range is basically the standard for widebody airliners. which is absolutely fine for C929.

C929 cabin is wider than B-787 and almost same as A350.. information is available on this thread.

China being the latecomer has certain advantages, they can apply modern manufacturing techniques and material..
-----------------------------------------------------------------------------------------------------------------------------------

1. C929 composite material on airframe/wings would be more than B-787 and exceed 50% of total area. Note, contrary to C919 having a secondary alternative design (more composite), C929 has only one (composite) design from the conception.

2. The main load-bearing structures on C929 mainly use T800-grade carbon fiber/toughened epoxy materials, and the secondary load-bearing structures mainly use T300-grade carbon fiber/non-toughened epoxy materials.

3. C929 uses SLM to print titanium alloy wing brackets, achieving a 30% weight reduction and a 20% strength increase.
-------------------------------------------------------------------------------------------------------------------------------
comparison with 787-900 numbers

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61.81m long, 60.12m wingspan, 17.02m high, fuselage cabin width is 5.49m and external width is 5.77m
MTOW is 254.7t
max payload 53t

so in comparison, C929 is 1m longer in total length
3m longer wingspan
MTOW is 7t lower
payload is 2.5t lower

The MTOW is lower with similar payload, so i guess is that the empty weight is lower due to structural design and composite material. And it would need to be lower to be competitive. coz its a clean-sheet design.

so C929 will be a modern/competitive machine. and sometime you don't need cutting edge product as long as you are able to manufacture/design same category class machine. means widebody airliner.

Click to expand...

I understand the theory and technology behind it but IMO comparing it to the B781 isn't really fair considering it carries 50 more passengers for similar range/MTOW as the C929 STD version. B789 is the closest competitor and still for similar weight class it manages more passengers and much more range. I'm not sure an extra 7 tons worth of MTOW would make up for ~10 extra pax(Also how'd Boeing fit in more passenger into a physically smaller aircraft) and 1000nmi extra range.

The number just isn't computing, if C929 has a lighter empty weight for the same carrying capacity/size, for similar MTOW, C929 would be able to manage a higher fuel fraction hence more range. So, assuming C929 do indeed have a lighter structural weight than B789 due to more advanced composites(Which is very likely due to what we've seen in the military sector and what you've posted), for the same/similar payload and similar MTOW C929 would manage to carry more fuel if not similar amount of fuel(I found a source saying 103t of fuel at max capacity compared to B789's 101t). According to the range equation C929 either have less efficient engines or less efficient aerodynamics for it to manage lower range but considering C929 would likely have the same engine options as the B789, we could probably eliminate that as a possibility thus only leaving less efficient/more conservative aerodynamic design. If I remember correctly range for airliners are usually calculated assuming standard conditions with full pax(and their related cargo) in a standard two class layout and max fuel factoring in reserves. Hence its burning more fuel to haul less payload across a considerably shorter distance which IMO limits its attractiveness for any foreign customer that isn't being heavily subsidized by the government. Could also be bad domestically as it'll bleed the government of money from all the subsidy it'll have to pay for the increased fuel consumption that or let the passengers pay for the extra operational costs.

It's not really the design range I'm worried about, of course B789 don't actually fly at their max range operationally but it's just what could be inferred from public specs that is really worrying. Unless COMAC has a completely different way of calculating their specs compared to everyone else.

Tomboy said:

I understand the theory and technology behind it but IMO comparing it to the B781 isn't really fair considering it carries 50 more passengers for similar range/MTOW as the C929 STD version. B789 is the closest competitor and still for similar weight class it manages more passengers and much more range. I'm not sure an extra 7 tons worth of MTOW would make up for ~10 extra pax(Also how'd Boeing fit in more passenger into a physically smaller aircraft) and 1000nmi extra range.

The number just isn't computing, if C929 has a lighter empty weight for the same carrying capacity/size, for similar MTOW, C929 would be able to manage a higher fuel fraction hence more range. So, assuming C929 do indeed have a lighter structural weight than B789 due to more advanced composites(Which is very likely due to what we've seen in the military sector and what you've posted), for the same/similar payload and similar MTOW C929 would manage to carry more fuel if not similar amount of fuel(I found a source saying 103t of fuel at max capacity compared to B789's 101t). According to the range equation C929 either have less efficient engines or less efficient aerodynamics for it to manage lower range but considering C929 would likely have the same engine options as the B789, we could probably eliminate that as a possibility thus only leaving less efficient/more conservative aerodynamic design. If I remember correctly range for airliners are usually calculated assuming standard conditions with full pax(and their related cargo) in a standard two class layout and max fuel factoring in reserves. Hence its burning more fuel to haul less payload across a considerably shorter distance which IMO limits its attractiveness for any foreign customer that isn't being heavily subsidized by the government. Could also be bad domestically as it'll bleed the government of money from all the subsidy it'll have to pay for the increased fuel consumption that or let the passengers pay for the extra operational costs.

It's not really the design range I'm worried about, of course B789 don't actually fly at their max range operationally but it's just what could be inferred from public specs that is really worrying. Unless COMAC has a completely different way of calculating their specs compared to everyone else.

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Civilian aircraft range is heavily dependent on the performance and efficiency of its engines. C929 have same Engine option.. most probably Trent7000 for initial variants. aircraft also has composite wings which further increase the efficiency.

so we cannot say much about Aerodynamics. its too early to talk.. and we don't know how COMAC is calculating all these things.

C929 Fuselage is currently under construction so are wings and other parts.

i m waiting for more information.

Tomboy said:

It's not really the design range I'm worried about, of course B789 don't actually fly at their max range operationally but it's just what could be inferred from public specs that is really worrying. Unless COMAC has a completely different way of calculating their specs compared to everyone else.

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It’s possible that COMAC uses a different max range figure from Boeing and Airbus. I’ve seen before (but can’t confirm) that maybe Airbus and Boeing’s range figure involve less conservative emergency reserve fuel margins.

latenlazy said:

It’s possible that COMAC uses a different max range figure from Boeing and Airbus. I’ve seen before (but can’t confirm) that maybe Airbus and Boeing’s range figure involve less conservative emergency reserve fuel margins.

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If they do, IDK why they wouldn't tell anyone considering right now airlines reps/aviation journalists are going to see that spec, assume they used the same method as Boeing/Airbus and get the (logical) conclusion that C929 is not as good as B789/A350. This is after all a product they want to actually sell and be competitive against western alternatives. Could be another case of shitty marketing as usual for state owned companies.

We should probably wait for further information/spec, but IMO they aren't doing too good of a job at advertising. Just hope COMAC don't become the next case of Tupolev/Ilyushin airliners where they never get competitive on the international market(And even domestic market) due to high operational costs and outdated design and eventually losing support from the government due to being a money sink while not making progress. I hate to say this but going by spec/efficiency/domestication wise, the Russians with the MC-21 are literally doing much better than COMAC with the C919 despite being heavily sanctioned and deprived of funding.

Illyushin and Tupolev had some highly successful designs. For example the Il-62.
It is just by the late 1970s the designs were outdated.
As you can guess for a major oil producer like the Soviet Union low fuel consumption wasn't as much a priority. With the 1970s oil crisis and the rise in fuel costs worldwide, this made their aircraft less export competitive. They were also slower to embrace cockpit automation because of the lag in Soviet microcircuit technology.

I doubt Chinese aircraft won't have a heavy focus on low fuel consumption given China's status as an oil importer.

Tomboy said:

If they do, IDK why they wouldn't tell anyone considering right now airlines reps/aviation journalists are going to see that spec, assume they used the same method as Boeing/Airbus and get the (logical) conclusion that C929 is not as good as B789/A350. This is after all a product they want to actually sell and be competitive against western alternatives. Could be another case of shitty marketing as usual for state owned companies.

We should probably wait for further information/spec, but IMO they aren't doing too good of a job at advertising. Just hope COMAC don't become the next case of Tupolev/Ilyushin airliners where they never get competitive on the international market(And even domestic market) due to high operational costs and outdated design and eventually losing support from the government due to being a money sink while not making progress. I hate to say this but going by spec/efficiency/domestication wise, the Russians with the MC-21 are literally doing much better than COMAC with the C919 despite being heavily sanctioned and deprived of funding.

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Public advertising doesn’t matter for sales. What matters is the detailed specs given to airliners based on their specific fit out, trim, and operational requirements.

gelgoog said:

Illyushin and Tupolev had some highly successful designs. For example the Il-62.
It is just by the late 1970s the designs were outdated.
As you can guess for a major oil producer like the Soviet Union low fuel consumption wasn't as much a priority. With the 1970s oil crisis and the rise in fuel costs worldwide, this made their aircraft less export competitive. They were also slower to embrace cockpit automation because of the lag in Soviet microcircuit technology.

I doubt Chinese aircraft won't have a heavy focus on low fuel consumption given China's status as an oil importer.

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Well, if you calculate the fuel efficiency per seat(Pretty common metric for airliner performance) for the C929 from official specs at the airshow, it comes out at 23.7 percent lower compared to the B789. Hell, you could compare it to the old B764-ER(Of a smaller weight class with 40 less pax) with CF-6s, and you'll find that it is somehow still more efficient than the C929 by 5 percent. However, for the sake of hopium, C929's specs might not be final.

But for C919-100-ER's specs compared to its closest competitor the B737MAX-7(B737MAX also uses less efficient engines because of ground clearance hence LEAP-1B has only a BPR of 9 compared 11 for LEAP-1A/C) has 17 percent less fuel efficiency per seat. Even MC-21-300 with PW1000G is 7 percent more efficient by the same metric which IMO is just embarrassing. C919-100-ER's specs is more similar(4 percent more efficient) to the B737-800 from 20 years ago with much less efficient CFM-56 engines(So, judging by aerodynamic efficiency it is likely the 20 year old 737NG is more efficient). IDK how COMAC stooped this low(How is CJ-1000A still not ready even with clear signs for years that LEAP-1C supply might be cut) especially with a booming military aviation industry in China. Because without some major changes, China isn't going to be competitive with western commercial aviation for decades.

latenlazy said:

Public advertising doesn’t matter for sales. What matters is the detailed specs given to airliners based on their specific fit out, trim, and operational requirements.

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Yes, of course, specific performance would be calculated with each airline's requirement(Normally, it doesn't affect range too much unless for some reason the airline wanted to goldplate the interior). But there's no reason to shoot themselves in the foot by advertising worse specs(Assuming they are false for some reason?) cause every aircraft manufacturer realistically go by more or less the same standard(might vary a bit given the interior decoration/furnishing that comes standard for each aircraft) when it comes to performance specs.