Quoting kurtverbose (Reply 99): Don't mis-quote me.

No harn intended. The point I was making, is that there are way bigger things at stake than just the "322 or the longer range 321"

Quoting packsonflight (Reply 100): No harn intended.

I know - I wasn't offended, it's just you quoted me on reply 96, but that's not what I wrote on reply 96. The text you quoted was by roseflyer in post 95.

I think it's airliners.net software being confused.

Quoting roseflyer (Reply 95): Reducing hydraulic systems and removing LRUs is going to have an impact on most of the fault trees in the flight control system.

The A320 series only has two engine driven hydraulic pumps, the blue hydraulic system is electrically powered. As for removing/adding LRUs, that has been happening without much problem on many Boeing types over the years.

Quoting roseflyer (Reply 95): That is going to take a lot of analysis and cost a lot of money to do.

They have done the work, its called the A350.

Quoting roseflyer (Reply 95): That scope of change would approach the limits of an amended type certification similar to what Boeing did with the 747-8.

The dash 8 is a different beast to the A320. Airbus has basically the same feel from the A320 to the A380 by using FBW, the dash 8 upgrade suffered by not have a more extensive FBW architecture.

Quoting roseflyer (Reply 95): I also think there is less benefit for a narrowbody to have electrohydraulic flight control actuators. If I understand the architecture, the primary benefit to doing that is reduced weight from hydraulic fluid and plumbing

reduce weight, improve redundancy, simplicity, at the same time giving the pilots the same look and feel via FBW.

Quoting zeke (Reply 102): Quoting roseflyer (Reply 95): Reducing hydraulic systems and removing LRUs is going to have an impact on most of the fault trees in the flight control system. The A320 series only has two engine driven hydraulic pumps, the blue hydraulic system is electrically powered. As for removing/adding LRUs, that has been happening without much problem on many Boeing types over the years.

Removing the backup electrically powered system and going to independent closed loop hydraulics is possible, but going to require a lot of certification work and carry quite a bit of risk.

Quoting zeke (Reply 102): Quoting roseflyer (Reply 95): That is going to take a lot of analysis and cost a lot of money to do. They have done the work, its called the A350.

Rarely do fault trees and certification analysis and testing cross different airplane models. The analysis work and components would not carry over to the A320. Airbus would still have to demonstration 25.1309 compliance, which would be a whole new set of analysis. The A350 is a low cycle high hour airplane. The A320 is certified for much higher cycles. Components are unlikely to carry over due to different sizes and loads. The analysis can be done, but such drastic architecture changes are going to cost $1 billion or more. Extending the current wing and adding in more composite structure while keeping the systems architecture the same would be much much cheaper. I agree that the architecture on the A350 is advanced and has benefits, but I doubt those would be cost effective to transfer to an existing platform.

Quoting zeke (Reply 102): Quoting roseflyer (Reply 95): That scope of change would approach the limits of an amended type certification similar to what Boeing did with the 747-8. The dash 8 is a different beast to the A320. Airbus has basically the same feel from the A320 to the A380 by using FBW, the dash 8 upgrade suffered by not have a more extensive FBW architecture.

What I am talking about is not the FBW vs conventional control debate. I am talking about opening up every single flight controls fault tree. Removing hydraulic systems and consolidating LRUs is going to have a huge impact on the fault trees because you are taking away redundancy. I doubt any of the existing certification work can be used to demonstrate 25.1309 compliance since the failure mode and effects analysis for flight control failures frequently results in hazardous and catastrophic conditions. Airbus has to demonstrate the probabilities of hazardous failures at 1x10^-7 and catastrophic to the -9. Removing redundancy is going to require that it be put back in the fault tree. New designs have to have demonstrated or tested reliability numbers which results in some expensive qualification and design testing.

The 747-8 ended up with some really challenging design challenges with the latest FAR requirements. There are quite a few design compromises such as lightening strike applique issues, leading edge fault indication, load alleviation for flutter, and critical design configuration control limitation airworthiness limitations etc that came up in the design process. None of those were related to FBW, but rather modifications to the wing. Things like that come up when a new wing with new system architecture is added to an existing design. There are complicated and/or expensive engineering design workarounds and sometimes airlines have to pay for additional maintenance. If Airbus goes through with all the innovation from the A350 wing and puts it on the A320 type certification, they probably will have similar design challenges and some will push the limit of staying on the same type certification and may have to start over with all the fault tree analysis, which essentially leads to a new type certification. This can all be done, but there is a lot of risk and cost associated with it. Is there really enough efficiency gain from such drastic architecture changes? Clean sheet designs allow for so much more flexibility. How far does Airbus want to go? I think a stretch to the current wing while keeping the same architecture makes more sense, but I don't really know what the Airbus designers would be willing to do and how much efficiency they can gain from each incremental change.

[Edited 2016-03-30 06:23:51]

Quoting roseflyer (Reply 103): Rarely do fault trees and certification analysis and testing cross different airplane models.

Well you really dont know how Airbus had been doing their FBW updates for the best part of the last 30 years. They actually develop the software update on one model, and then release the software on the other. For example if an update was developed on the A330, they would then release that update on the A320 series and A340.

Have a google on model based design, functional block diagrams, and automatic code generation.

Quoting roseflyer (Reply 103): The A350 is a low cycle high hour airplane. The A320 is certified for much higher cycles.

Absolutely irreverent, almost like you are trying to make up reasons why it could not be done.

Quoting roseflyer (Reply 103): Components are unlikely to carry over due to different sizes and loads. The analysis can be done, but such drastic architecture changes are going to cost $1 billion or more.

Again this is irreverent to FBW. The pilot/autopilot will command a control system command, the FBW will command a rate to meet that demand as a feedback loop, and then send the command for the actuator to move electronically to the actuator on the control surface. The FBW does not care what sort of load the surface is experiencing (the actuators are sized in response to the air loads), it just sends commands to move, and looks at the resulting trajectory change.

Quoting roseflyer (Reply 103): Removing hydraulic systems and consolidating LRUs is going to have a huge impact on the fault trees because you are taking away redundancy.

As I said above you are actually improving redundancy. The A320 cannot fly with a total loss of hydraulics, putting electrohydraulic actuators in the system the aircraft can happily fly with no hydraulics, as each electrohydraulic actuator will then have its own closed loop hydraulic circuit. The A350 will happy fly with the loss of all air data probes, even with the autopilot on, on the A320 that would be back to direct law with no autopilot being availabe. In the event of the loss of all air data, the A350 uses the air data computers on each engine as the backup to the aircraft air data system and displays that on the PFD.

Quoting zeke (Reply 104): Well you really dont know how Airbus had been doing their FBW updates for the best part of the last 30 years. They actually develop the software update on one model, and then release the software on the other. For example if an update was developed on the A330, they would then release that update on the A320 series and A340. Have a google on model based design, functional block diagrams, and automatic code generation.

Zeke I don't think you understand my comments since I am not talking about fly by wire control laws. I have a masters degree in engineering, have worked on functional block diagrams and model based design and also worked on failure mode and effects analysis and fault tree analysis relative to airplane design. What you are suggesting about software comparisons to the A350 won't address the huge certification hurdle associated with the design changes that you suggested here:

Quoting zeke (Reply 92): The way I would suggest they would proceed would be to simplify the wing/engine systems like the A350, reduce the hydraulic systems down to two, electrohydraulic flight control actuators, high speed ADFX, removing all the LRUs and replacing them with a blade server like the A350. The A350 has shown Airbus how they can simplify system architecture to reduce weight, and improve redundancy at the same time.

You suggested reducing hydraulic systems and electrohydraulic flight control actuators and simplifying the flight control system. I don't know why you think FBW software updates are relevant to the certification testing associated with removing and changing the mechanical components. Software failures or inconsistencies are usually not in that many fault trees for 25.1309 compliance. Failure of actuators, hydraulic systems, electrical systems, hinges, joints, surface damage, etc are all in the fault trees. Removing a hydraulic system is going to significantly change the levels of redundancy associated with Airbus demonstrating compliance to the FARs that state that the probability of a catastrophic event has to be less than 1 in a Billion. The hydraulic system has to be replaced by an independent electro hydraulic actuator. That system then has to be tested to determine reliability and also have adequate separation and independence from other failures. This type of analysis is expensive and requires significant lab testing of mechanical components as well as flight testing demonstrating that each failure condition won't affect safe flight for the entire flight envelope. These type of changes you are proposing are going to result in discarding almost all of the flight control system fault trees and starting over. I am not talking about control laws. I'm talking about fault trees for loss of a hydraulic system with an engine out, or a jam in the control path, or uncommanded slat/flap extension or loss of airspeed data, trim runaway, hardover aileron, rudder, elevator or spoiler, etc. There are so many failure modes identified in the functional hazard assessment.

Here is a short list of CFRs that the redesign that you are talking about is going to impact:
25.629 Aeroelastic stability for Flutter
25.631 Birdstrike
25.671 Control Sytems
25.672 Stability Augmentation
25.685 Control System Details
25.697 High Lift and Drag Devices

Remember that Airbus has to demonstrate compliance to the basic concept of a single failure shall not prevent continued safe flight and landing and that the probability of a failure condition shall be consistent with its severity. Demonstrating that a design meets that intent takes years of work for the amount of change you are suggesting.

Quoting zeke (Reply 104): Quoting roseflyer (Reply 103): The A350 is a low cycle high hour airplane. The A320 is certified for much higher cycles. Absolutely irreverent, almost like you are trying to make up reasons why it could not be done.

Zeke, you suggested changing the mechanical components and then suggested that similar architecture and software on the A350 means they have done the work. Changing conventional FBW hydraulic actuators to an electrohydraulic architecture is a big change. These would likely be all new actuators and nothing carried over from the A350. That is going to take a lot of development work and certification testing.

Quoting zeke (Reply 104): Quoting roseflyer (Reply 103): Components are unlikely to carry over due to different sizes and loads. The analysis can be done, but such drastic architecture changes are going to cost $1 billion or more. Again this is irreverent to FBW. The pilot/autopilot will command a control system command, the FBW will command a rate to meet that demand as a feedback loop, and then send the command for the actuator to move electronically to the actuator on the control surface. The FBW does not care what sort of load the surface is experiencing (the actuators are sized in response to the air loads), it just sends commands to move, and looks at the resulting trajectory change.

Irrelevant to software? Yes. Irrelevant to the cost and complexity of design and certification, absolutely not. All new hardware and control logic associated with the changes that you suggested is going to require a lot of certification work. FBW and software doesn't care, but FBW software is only a small piece of the over flight control system certification process.

Quoting zeke (Reply 104): As I said above you are actually improving redundancy. The A320 cannot fly with a total loss of hydraulics, putting electrohydraulic actuators in the system the aircraft can happily fly with no hydraulics, as each electrohydraulic actuator will then have its own closed loop hydraulic circuit.

I agree with the logic. I point out again however that changing the redundancy and logic means that you are basically scrapping every existing fault tree demonstrating compliance as described by AC 25.1309 and starting over. This is going to cost a lot and open up a ton of risk.

[Edited 2016-03-30 11:21:39]

[Edited 2016-03-30 11:31:30]

[Edited 2016-03-30 11:36:33]

Quoting roseflyer (Reply 105): don't know why you think FBW software updates are relevant to the certification testing associated with removing and changing the mechanical components

Yet you claim to have "a masters degree in engineering, have worked on functional block diagrams and model based design and also worked on failure mode and effects analysis and fault tree analysis relative to airplane design" yet cannot see the relevance. A person with that sort of background would know about auto code generation, and how it will automatically generate the code for the different hardware. and the code generation automatically is performed for the various target flight control computers (different hardware).

Airbus has been for decades deploying FBW technology developed on one type onto another. They will do a software update on say the A330, and then deploy that update to the A320 series and A340, the A320s/A330s/A340s all share the same baseline FBW. They use model-based design with autocode generation, that automatically will generate the code fro the target hardware. Engineers develop the design within the tool, and the tool generates code that can either be used in a strictly software environment for analysis, or sent off for integration and certification/validation on flight-ready hardware.

The FBW model is independent of the hardware, they already have the same FBW software deployed on different hardware.

Quoting roseflyer (Reply 105): Failure of actuators, hydraulic systems, electrical systems, hinges, joints, surface damage, etc are all in the fault trees.

Which is already accounted for in the FBW model, that is why the FBW model is able to automatically reconfigure itself in response to failures.

Quoting roseflyer (Reply 105): Removing a hydraulic system is going to significantly change the levels of redundancy associated with Airbus demonstrating compliance to the FARs that state that the probability of a catastrophic event has to be less than 1 in a Billion.

Geez you really sounds like the biggest Boeing fanboy at times, all these reasons why Airbus cannot do something when it is just a matter of doing the same engineering they have proven capability with.

One of the justifications for the A380/A400/A350 flight control system was the A320, they were able to show that the electrohydraulic actuators on that baseline were like electric blue hydraulic system on the A320. If they used electrohydraulic actuators, that blue hydraulic system would still exist, it would be located in each electrohydraulic actuator instead of a central pump and additional hydraulic circuit.

Your talking about FAR 25.1309, and Airbus has been meeting this requirement the same way across all FBW types. They use the same basic building blocks with a fail safe command and monitoring computers. These computers have stringent safety requirements and are functionally composed of a command channel and a monitoring channel.

Quoting roseflyer (Reply 105): That system then has to be tested to determine reliability and also have adequate separation and independence from other failures.

No one said no testing would be required. But that is not to say that testing has to be done on this aircraft, Airbus has tested many flight control systems for new types on their other test aircraft, hardware in the loop in test rigs, and by software. A lot of the A350 flight control system was flight tested on other types before the A350 ever flew, and in fact was already certified on the A380 and A400.

You obviously dont know much history on the Airbus FBW to know they actually use the same software across various types, with different hardware. The A380/A400/A350 all share the same baseline, as does the A320/A330/A340.

Quoting roseflyer (Reply 105): Changing conventional FBW hydraulic actuators to an electrohydraulic architecture is a big change

If you say so dear. A person with masters in engineering would know the FBW just sends electrical signals to the actuators, the internal workings of the actuators are certified independently.

Quoting roseflyer (Reply 105): These would likely be all new actuators and nothing carried over from the A350.

Again, this has not been a problem when they were able to use the same software on the A380/A400/A350.

Zeke, you keep talking about software, and I'm not talking about the software. I'm talking about certification for the entire system including hardware.

Quoting zeke (Reply 106): Geez you really sounds like the biggest Boeing fanboy at times, all these reasons why Airbus cannot do something when it is just a matter of doing the same engineering they have proven capability with.

You can call me names like being the biggest Boeing fanboy if you want, but I'm not saying Airbus can't do something. I am saying that it is going to be very expensive to do the changes you suggested and sharing my opinion that I don't know if the benefit from such architecture changes are worth the time, cost and risk associated with them.

Software being designed to deal with failures is different from certification fault trees that need to demonstrate what the probability of failures are and that they comply with 25.1309. I have no doubt that Airbus can make the changes you suggest work. I do wonder if it makes any sense to do it.

Quoting zeke (Reply 106): The FBW model is independent of the hardware, they already have the same FBW software deployed on different hardware.

Yes, but that hardware still needs to be analyzed and certified. Again, I haven't questioned the software. I keep stating that the hardware changes need to be analyzed and the fault trees have to be redone. Having seen the functional hazard assessments for different airplanes, I would estimate that the software is about 20% of the total fault tree analysis but that is a loose guess.

Quoting zeke (Reply 106): Your talking about FAR 25.1309, and Airbus has been meeting this requirement the same way across all FBW types. They use the same basic building blocks with a fail safe command and monitoring computers. These computers have stringent safety requirements and are functionally composed of a command channel and a monitoring channel.

Building a fail safe design goes hand in hand with the probability of each failure. The flight control software does have fail safe command and monitoring, but that does not mean that it doesn't fail.

Quoting zeke (Reply 106): Quoting roseflyer (Reply 105): Changing conventional FBW hydraulic actuators to an electrohydraulic architecture is a big change If you say so dear. A person with masters in engineering would know the FBW just sends electrical signals to the actuators, the internal workings of the actuators are certified independently.

You keep ignoring the hardware reliability aspect of 25.1309. The FARs require quite a bit of analysis for this change. I will walk you through an example functional hazard assessment.

What are the potential failure modes of an electrohydraulic aileron actuator system?

1. Loss of electrical signal to actuator
1a. Flight Control Computer failure
1b. Ground or short in control wire
2. Failure of the actuator to respond to commanded signal
2a. Fluid leak
2b. Seized actuator
2c. Cracked rod end
2d. etc
3. Uncommanded actuator motion
3a. Internal leakage
3b. Piston failure
3c. False signal
4. Loss of indication
4a. Aileron position not being indicated
4b. Incorrect position being indicated

Next each and every failure mode has to have a probability associated with it. For example internal leakage may occur 1 in every 10000000000 flights. These numbers need to be developed for testing or analysis. For the most part qualification based on testing is used for new designs whereas qualification based on experience or analysis can be used for carryover designs. This is where a lot of money can be saved if a design is determined to be similar to existing designs. Otherwise testing is done in the lab environment.

Next you have to look at what the effect of each failure is
1. Inability to respond to control input
1a. Limited roll control
2. Uncommanded control input
2a. Excessive roll input

Each of these various events has to fall under the category of minor, major, hazardous or catastrophic. Uncommanded roll input and inability to maintain level flight would probably end up catastrophic, so the probability of that failure happening would have to be 1 in a billion. The probability of each event that could tree up to the top level hazard event needs to be multiplied. There are some other multipliers in there two since there are failure modes like internal leakage which cannot typically be detected. Maintenance task intervals need to be factored in to determine what the exposure time to such a failure is. Much of the general fault tree and functional hazard assessment can be copied but not the entire fault tree. Failure probability rates will be different and the exposure time due to different maintenance program intervals will be different so even the same tree will have different multipliers.

All the probabilities of failure need to be analyzed for each airplane because of the design life. Carryover concepts from other airplanes that were intended for lower cycle operation may not meet the more rigorous requirements for a narrowbody.

Quoting zeke (Reply 106): Quoting roseflyer (Reply 105): Failure of actuators, hydraulic systems, electrical systems, hinges, joints, surface damage, etc are all in the fault trees. Which is already accounted for in the FBW model, that is why the FBW model is able to automatically reconfigure itself in response to failures.

The FBW system is designed to account for a failure, but it doesn't eliminate the hazard. What happens if an uncontained engine failure occurs that causes a flap skew? With the loss of a hydraulic system associated with the engine failure, does the airplane still have enough roll, yaw and pitch control to maintain safe flight and land? Fly by wire software is not going to tell you if excess yaw can be induced that can't be controlled. This requires an engineer to analyze the condition and flight envelope and demonstrate using a fault tree that the probability of this event meets the 25.1309 requirements and that the plane can land assuming only one additional failure. There are probably 1,000 fault trees and each one has to be carefully built and analyzed.

Quoting zeke (Reply 106): Quoting roseflyer (Reply 105): These would likely be all new actuators and nothing carried over from the A350. Again, this has not been a problem when they were able to use the same software on the A380/A400/A350.

Correct, and look at how long the development of those programs took. If Airbus decides to do such significant changes to the baseline flight control architecture on the A322 as you suggest, it will be a 4 year multi billion dollar development program. There is a reason that both Airbus and Boeing are trying to do minimum change derivatives to reduce certification burden. Some call this grandfathering, but there is a well regulated process to be followed for design changes. For this reason I would imagine a five foot wing root extension like the DC9-50 to MD80 would be more likely and not a massive overhaul like the A340-600.

[Edited 2016-03-30 13:18:52]

[Edited 2016-03-30 13:43:53]

[Edited 2016-03-30 13:46:01]

Nobody is saying it is going to be cheep to redo the systems for the 322 and in fact it is going to cost a lot of money, but after doing the A380, A400 and the A350 in a relatively short time the program must qualify as a low risk no moonshot kind of thing.

Low risk is the key word here, and if Airbus can invest in development of next gen narrow body systems and production technology, for an aircraft that is produced in relatively small numbers, it takes away the biggest part of the risk associated with quick production ramp up of the next gen platform.

Quoting roseflyer (Reply 107):

You are just forgetting that Airbus is actually doing what you deem impossible, or too expensive, and they are not waiting for the A322, they are doing it on the A320 series.

https://www.flightglobal.com/news/articles/a320-flies-with-electrical-aileron-actuator-354481/

Airbus does move the technology from frame to frame. Yes it has to be certified, but something you have certified for one frame is less work to certify for the next. You do not wait for the big jump, but are doing it step by step one piece at the time. A big part of your list is actually not frame depended, but you can use the work done once many times.
When the time comes around to do the A322 Airbus will already have most of the work done in the A320.

Quoting mjoelnir (Reply 109): Quoting roseflyer (Reply 107): You are just forgetting that Airbus is actually doing what you deem impossible, or too expensive, and they are not waiting for the A322, they are doing it on the A320 series. https://www.flightglobal.com/news/articles/a320-flies-with-electrical-aileron-actuator-354481/ Airbus does move the technology from frame to frame. Yes it has to be certified, but something you have certified for one frame is less work to certify for the next. You do not wait for the big jump, but are doing it step by step one piece at the time. A big part of your list is actually not frame depended, but you can use the work done once many times. When the time comes around to do the A322 Airbus will already have most of the work done in the A320.

I had no idea that Airbus did that. Awesome! I never ever said it was impossible. I did say it is expensive and it is to implement that type of innovation on an existing platform. I also questioned whether it makes business sense to do a change that dramatic. I think a bigger wing would be important for an A322 but don't go as far as suggesting a full overhaul of the flight control system, architecture and hardware like Zeke suggested.

To reiterate my point, here is a quote from that article:

"the event was the result of three years' research and technology work with Airbus and other partners."

Three years of work to get to one actuator. This article was from 2011 and said a fully electro hydraulic wing could be available in 2015. That means it was 7 years of development work. That supports what I am saying that it is costly and a long certification and testing process.

What ever happened to this?

Quoting packsonflight (Reply 108): Low risk is the key word here, and if Airbus can invest in development of next gen narrow body systems and production technology, for an aircraft that is produced in relatively small numbers, it takes away the biggest part of the risk associated with quick production ramp up of the next gen platform.

I am a believer in the low risk concept. An all new electro hydraulic wing sounds like it has potential but here is a lot of risk as well as time and money required to implement it on the A320 family. I don't know if It makes sense for Airbus to do that.

[Edited 2016-03-30 14:12:39]

Quoting roseflyer (Reply 110): What ever happened to this?

I would assume that it is in the works. Flying on the old MSN1 most likely. That bird has been used for all the systems successive appearing on the A320 series. That application is for thin wings, being the change from the A380, 350, 400 application.
I think some people do not realize how much work is done on the A320 and how much that bird has changed during the years, without ever going to the big jump. At Airbus a successful technology not being moved to the next frame would be the exception.

Quoting mjoelnir (Reply 111):

I totally agree that the A320 has seen significant design improvement over time. I am a proponent of the A322 idea. I do question how far makes sense since the more design changes incorporated the higher the cost and risk.

Quoting astuteman (Reply 49): Quoting roseflyer (Reply 46): The popularity of the A321 tends to be overstated on A.net. While the A321 popularity has grown, it still only represents about 30% of orders It's a fair point.

Looking only at order understates the A321's importance. Many "A320 orders" are for unspecified members of the A320 family, and even many A320-specific orders can be converted upwards.

A better metric is deliveries.
A321 was 37.5% of deliveries in 2015 and has been increasing its share every year.
A321neo appears to have improved over the A321ceo by more than the A320neo will over A320ceo.
I recall Airbus predicting that A321neo would be ~50% of deliveries soon. Wouldn't be surprised.

Quoting astuteman (Reply 56): Airbus are not going to move until Boeing declare their hand on MOM

The recent Leeham note of the MoM suggest analyst trepidation over whether Airbus' A322 response could kill MoM program profitability. The A322 might be a bad move in a world that already has the MoM, but the MoM would almost certainly be a bad move in a world that already has the A322. Perhaps the game-theoretical optimum for Airbus is to launch the A322 first, before Boeing does the MoM. I can't see Boeing's BoD credibly threatening a clean-sheet MoM any time soon following an A322 launch. The A322 would grab the MoM market but also consolidate Airbus' overall narrowbody dominance for reasons of commonality. Indeed, with Astuteman's sketched "ENEO" family we could see many operators switching from 737 entirely to preserve commonality between short and long-haul fleets.

Quoting astuteman (Reply 84): New wing reduces drag to give another c. 200Nm

Always appreciate a stab at "first principles" airliner estimation. You might be too conservative here.
Remember that the A320 wing is a decade behind the 737NG's wing - it's thinner and therefore heavier than it would be if built today. The combination of CFRP and the latest supercritical airfoil profile could get a very significant span extension at zero weight delta.

-12% greater span would give ~25% less induced drag at equal weight
-assuming Di is ~33% of drag, that's ~8% less drag, giving over 300nm range extension
-Wing could be bigger for little weight penalty
-Bigger wing could allow more MTOW without new MLG (lower rotation requirement) and with simpler, light, cheaper high lift devices than the A321's double-slotted flaps.

Quoting astuteman (Reply 84): We can challenge the assumptions of course

Of course, as I've done above. Yours are reasonable, others are reasonable, the takeaway to me though is that perhaps Airbus should move first and fence Boeing out of this sector for broader strategic goals in addition to the utility/profit of the A322 or "ENEO" family itself.

...of course that would not be the optimal game play in the duopoly if Airbus ravaged Boeing's NB business so badly that it forced an NSA earlier than it otherwise would. Airbus' "sweet spot" equilibrium might be the 60/40 split for a decade or two - enough to be winning but not enough to force the duopoly partner into rocking the boat.

Quoting Matt6461 (Reply 113): Many "A320 orders" are for unspecified members of the A320 family

What do you mean by this? All Airbus A320 family orders are booked to specific models. There are no 'generic A320S' orders in the backlog.

Quoting Matt6461 (Reply 113): Always appreciate a stab at "first principles" airliner estimation. You might be too conservative here. Remember that the A320 wing is a decade behind the 737NG's wing - it's thinner and therefore heavier than it would be if built today. The combination of CFRP and the latest supercritical airfoil profile could get a very significant span extension at zero weight delta.

"10 years behind"

going by some NASA doc the 737NG "shows elements of a supercritical wing". it is not fully "there".
NG wing evolution seems to be comparable to the 744 to 748 transformation.

Quoting scbriml (Reply 114): What do you mean by this? All Airbus A320 family orders are booked to specific models.

My take: a number of orders recorded as A320 may be (easily) transferable to A321(neo) at some point in the future. With pricing details for such conversion already agreed.

Recording an order as A320 rather than A321 reduces upfront investment as down payment will be lower. OK, not very much. But when one order in big double digit, or even triple digit, things start to add up rapidly.

Quoting WIederling (Reply 115): going by some NASA doc the 737NG "shows elements of a supercritical wing". it is not fully "there".

Show me one production aircraft that has a "pure" supercritical wing. Everyone makes compromises to apply the laboratory concept of a supercritical airfoil into a buildable,flyable wing.

Quoting PW100 (Reply 116): My take: a number of orders recorded as A320 may be (easily) transferable to A321(neo) at some point in the future. With pricing details for such conversion already agreed.

This is probably correct. We've seen a steady increase in the A321's share of CEO deliveries; two things dictate that this trend will continue: (1) upgauging as traffic/congestion increases, (2) the better relative position of the A321neo within the NEO family.

If A321 had 37.5% delivery share in 2015, I have to believe it will be higher in 2025.

Quoting WIederling (Reply 115): going by some NASA doc the 737NG "shows elements of a supercritical wing". it is not fully "there". NG wing evolution seems to be comparable to the 744 to 748 transformation.

Ok fine. I'm not saying that the 737NG wing is the latest in tech; I'm just saying it's newer, thicker, and therefore relatively lighter than the A320 wing. Do you dispute that?

I'm also saying this is an opportunity for Airbus rather than a drawback. The A320 would benefit from a new wing more than would a 737.

It's also telling that Airbus' NB at least matches Boeing's in per-seat efficiency despite (1) a wider, heavier fuselage and (2) older wing technology.

[Edited 2016-03-31 13:01:30]

Quoting Matt6461 (Reply 118): It's also telling that Airbus' NB at least matches Boeing's in per-seat efficiency despite (1) a wider, heavier fuselage and (2) older wing technology.

Wider more draggy fuselage offset by better engines and better aerodynamics.
The A320 has the much cleaner design.
Efficiency advantage rising over distance traveled supports that.

MEW differences for A320 versus 737-800 were marginal last time data was available in the ACAPS.

Boeing was forced to improve the NG with first winglets then scimitar devices to "keep up".
( a beauty contest was definitely not the driver there. Same for the {breathless voice} "top looking Sky Interior" {} ordered by airlines for weight reductions and not much else.)

Quoting roseflyer (Reply 71): I think the plane needs bigger engines, a bigger wing and bigger gear. Those same things can be done to a 737 as well

Nope, Boeing has pinned itsself to a wall following an old (very good) model. Any changes to the gear for example and all the legacy permits for certification are gone out the window, they can change the engine and parts of the wing, but anything in the fuselage, cockpit o other systems are not possible retaining the current certificate.

Quoting mjoelnir (Reply 83): The economic side of business seems to be under appreciated by you.

I enjoy your posts very much, but in this case Id rather talk about the 322...

Quoting william (Reply 89): If it makes sense for Airbus to do an A322, then it makes sense for Boeing to do a Mad Max.

The 739 is a compromised design, going ageing in that route would make a subpar product … and airbus be really happy.

Quoting roseflyer (Reply 107): Zeke, you keep talking about software, and I'm not talking about the software. I'm talking about certification for the entire system including hardware.

The FWB system is like the operating system of the Airbus Family, the differences in aircraft are the application software, so its a lot easier now that Airbus has been developing both for 3 decades (at least). So no biggie I guess if the launch the A322 they would have a flying prototype in less than 2 years (provided they don't have anything in the pipeline-like the A350-8000)

TRB

Quoting WIederling (Reply 119): Boeing was forced to improve the NG with first winglets then scimitar devices to "keep up".

Quoting TheRedBaron (Reply 120): Nope, Boeing has pinned itsself to a wall following an old (very good) model. Any changes to the gear for example and all the legacy permits for certification are gone out the window, they can change the engine and parts of the wing, but anything in the fuselage, cockpit o other systems are not possible retaining the current certificate.

I love the revisionist history and armchair engineering on this site. Keep up the good work, gentlemen.   

Quoting TheRedBaron (Reply 120): I enjoy your posts very much, but in this case Id rather talk about the 322...

As the A322 is thought as a straight continuation of the A320 series, how to you imagine to discuss the A322 without talking about the A320 series?

Quoting TheRedBaron (Reply 120): Nope, Boeing has pinned itsself to a wall following an old (very good) model. Any changes to the gear for example and all the legacy permits for certification are gone out the window, they can change the engine and parts of the wing, but anything in the fuselage, cockpit o other systems are not possible retaining the current certificate.

Not True. 737NG was almost all new, with over 70% new parts. Including new landing gear. Still a "modified" 737 for certification, not a new plane.

The regulators have an interest in allowing legacy design that doesn't meet current certification requirements. That interest is that the proven safety and reliablity is worth more than a theoretical paper safety.

Both Boeing and Airbus use this.

Quoting XT6Wagon (Reply 123): The regulators have an interest in allowing legacy design that doesn't meet current certification requirements. That interest is that the proven safety and reliablity is worth more than a theoretical paper safety.

Maybe I should have phrased it deferentially to convey a clearer message: If changing the landing gear is an easy task in the 737 series why did Boeing did not change it on the longer versions of the series.... I asked the same question on the Boeing tour factory, and the guy over there told me they did all they could to avoid the recertification and of a lot of systems that changed would no the allowed in the new "version" Also It has been discussed before, I am not bashing Boeing, in fact its amazing how many miles have taken out of an old design, but its clear now they better make a new product to compete, hence the MOM or NSA.

The Airbus A320 has already been manufactured with a different landing gear for Air India, so I guess in this case that development gives them a good possibility to make a heavier A321 version.

Quoting DfwRevolution (Reply 121): I love the revisionist history and armchair engineering on this site. Keep up the good work, gentlemen.

Thanks ...  

TRB

Quoting DfwRevolution (Reply 121): I love the revisionist history and armchair engineering on this site.

There is no way around it.
At one point you have to stand up and correct the revisionists and "Geschichtsklitterer".

Quoting TheRedBaron (Reply 120): Nope, Boeing has pinned itsself to a wall following an old (very good) model. Any changes to the gear for example and all the legacy permits for certification are gone out the window, they can change the engine and parts of the wing, but anything in the fuselage, cockpit o other systems are not possible retaining the current certificate.

Quite a bit of similarity to Microsoft's Windows OS ( and ancillary apps )

To show good performance ( and compete against Linux ) a wide range of fast hacks poking "through" the system (bypassing defined interfaces) were introduced ( together with some incompatibilities in other domains: deviate from protocol definitions to force competing implementations to show an error while simultaneously ignoring the error on the "home side".
These tweaks later bit Microsoft soundly ( together with never having worked towards clean interfaces) and is one reason for excessive susceptibility to all kinds of infestation.

Quoting DfwRevolution (Reply 121): Quoting WIederling (Reply 119): Boeing was forced to improve the NG with first winglets then scimitar devices to "keep up". Quoting TheRedBaron (Reply 120): Nope, Boeing has pinned itsself to a wall following an old (very good) model. Any changes to the gear for example and all the legacy permits for certification are gone out the window, they can change the engine and parts of the wing, but anything in the fuselage, cockpit o other systems are not possible retaining the current certificate. I love the revisionist history and armchair engineering on this site. Keep up the good work, gentlemen.

While I'd like to focus on the A322, I can't help but notice comments like these that are blatantly wrong. The winglets were developed by a company founded by a group of retired Lockheed and Boeing engineers who realized the benefit of winglets in the 1990s. They put them on business jets, developed the winglets completely independent of Boeing and Airbus, went and convinced the airlines that blended winglets had a significant benefit and patented the design. Boeing welcomed Aviation Partners and formed a joint venture. Airbus refused a partnership after signing a MoU to form a partnership which resulted in lawsuits between Aviation Partners and Airbus for patent infringement since Aviation Partners believed that the Sharklet was a copy of their design. Winglets have a long convoluted story on both the A320 and 737, and it is not because "Boeing was forced to improve the NG with first winglets then scimitar devices to "keep up". An outside 3rd party company showed the airlines presentations on the benefits of winglets. Just because Boeing was willing to work with them and Airbus wasn't doesn't mean that the A320 has an efficiency advantage over the 737-800. Unless you look at trip costs and ignore seat count differences, the 737-800 is very competitive (depending on seat count and range, often has a fuel burn advantage per seat over the A320). The Airbus advantage is the A321 which has quite a few more seats than the 737-900 and better takeoff and landing performance, although the CASM difference is not that big. The A322 would really extend the Airbus narrowbody family and I believe would be a great addition, but there are some careful compromises that have to be made. It extends the advantage for Airbus in higher capacity narrowbody region.

Going back to the other poster, the 737 is not pinned against a wall. There are impacts from design changes on the 737 platform. It's not about keeping the current certificate, but it is about limiting the scope of change to reduce the certification effort and some redesign that would be associated with having to open up some existing designs to change. It's the same scenario that I explained to Zeke earlier. Boeing did not want to open up and redesign the evacuation system by lengthening the gear (not having overwing slides is a big weight savings) or completely redesign the master caution/warning system. These types of changes would be expensive, but wouldn't necessarily cause a new type certification.

If Boeing wanted to do what I suggested in that Airbus do for the A322 which is a lengthened wing, bigger gear, bigger engines, and longer fuselage, they can do it as well. Boeing would have to make some design changes like overwing slides and potentially change the flight deck controls. I am sure there are some things that Airbus would end up changing as well on the A322.

[Edited 2016-04-01 05:39:58]

Quoting roseflyer (Reply 127):

I'd not be too sure who's narrative here is revisionist or not.
( presenting the official "Boeing Story" has a good chance at being revisionist or even fictional at that.)

Quoting roseflyer (Reply 127): Airbus refused a partnership after signing a MoU to form a partnership which resulted in lawsuits between Aviation Partners and Airbus for patent infringement since Aviation Partners believed that the Sharklet was a copy of their design.

the patent was taken down due to vast amounts of prior art. ... and the patent as such being too unspecific.
Kratzer obviously didn't work from a vacuum.

The interesting and noteworthy point is when Boeing started to use winglet performance for competitive comparisons.

Quoting roseflyer (Reply 127):

Airbus could do an A322 in the size of an 757-200, or slightly bigger than that, with less changes. Airbus has to do a new wing, that is a given. But even the wing could be a changed one, instead of completely new.
With a bigger wing the power need for the engines go down.
The 757-200 started out with a MTOW of around 110 t and engines with 36,100 lbf. With that the 757-200 produced very good take off performance.
Make the wing big enough and the current A321 engines with around 35,000 lbf does not have to grow much to move a A322 with around with a MTOW of 105 to 110 t.

Two versions, original fuselage and an about 6m stretched to 50.5m fuselage. Bigger wing. MTOW not more than 110t. same engine as the A321, slightly opened up to 36.000 lbf. MLG strengthened, perhaps a double boogie. I do not know how far you could go with using two bigger wheels and tires instead.

You would have a rather low cost solution.

Boeing would have to do much more to make a 737 derivative of the same size without the hope of soundly beating this A322. A MoM, clean sheet, using all the new technology of the 787 would beat that A322 soundly, but be expensive to develop and I assume expensive to produce and take quite a time to market.

[Edited 2016-04-01 06:36:33]

mjoelnir wrote:

Quoting roseflyer (Reply 127):
Airbus could do an A322 in the size of an 757-200, or slightly bigger than that, with less changes. Airbus has to do a new wing, that is a given. But even the wing could be a changed one, instead of completely new.
With a bigger wing the power need for the engines go down.
The 757-200 started out with a MTOW of around 110 t and engines with 36,100 lbf. With that the 757-200 produced very good take off performance.
Make the wing big enough and the current A321 engines with around 35,000 lbf does not have to grow much to move a A322 with around with a MTOW of 105 to 110 t.

Two versions, original fuselage and an about 6m stretched to 50.5m fuselage. Bigger wing. MTOW not more than 110t. same engine as the A321, slightly opened up to 36.000 lbf. MLG strengthened, perhaps a double boogie. I do not know how far you could go with using two bigger wheels and tires instead.

You would have a rather low cost solution.

Boeing would have to do much more to make a 737 derivative of the same size without the hope of soundly beating this A322. A MoM, clean sheet, using all the new technology of the 787 would beat that A322 soundly, but be expensive to develop and I assume expensive to produce and take quite a time to market.[Edited 2016-04-01 06:36:33]

I guess much depends on the wing. Can it be beefed up or must it be replaced by an entirely new one. I guess much depends on what Boeing does, Airbus seems just fine with the A321CEO/NEO as is. If Boeing does a serious 737-10 or launched a MoM the playing field changes.

I agree with Keesje here 'It much depends on what Boeing does'.I would perhaps say 'totally depends'.They already have the -900 aced.Building a better A321NEO is not going to generate any extra sales,so why do it.If the -10 is a 'simple' stretch (which is bound to be range compromised)then again it probably won't bother them.
I personally cannot see Boeing launching a MOM right now and I don't think they have even suggested that they would.Their ain't no engine anyway.
Since there is no MOM engine on any drawing board the only thing (perhaps) that Airbus could do is a small 'simple' 321 stretch out to 250 economy seats at (Say)29" pitch.And trade this additional weight for range.So it would be a sort of mini 757-300.The only point in doing that is of course if there are new sales to be gained.There are only 50 odd 757-300's so that's not worth it.Are there (I don't know) loads of old 767's being misused on transcon routes?Thats the sort of market that might make such a 322 worth doing.If not then it's in their business interests to sit on their hands and print money with 321NEO sales!

einsteinboricua wrote:

Quoting Revelation (Reply 8):The first thing I thought of when I saw the pic of the US-built A321 was that it needs longer/bigger wings:
   I think only when the A321 wingspan is elongated will it truly be a 757 replacement. The seat count is there, but having the short wingspan means range is sacrificed.

The A321 has a truly super critical wing. and needs ( with current best of breed engines )
much less MTOW for similar payload performance.

Though I would not be too surprised if Airbus in the future gives the plane more wingspan. maybe with folding tips.

parapente wrote:

I agree with Keesje here 'It much depends on what Boeing does'.I would perhaps say 'totally depends'.They already have the -900 aced.Building a better A321NEO is not going to generate any extra sales,so why do it.If the -10 is a 'simple' stretch (which is bound to be range compromised)then again it probably won't bother them.
I personally cannot see Boeing launching a MOM right now and I don't think they have even suggested that they would.Their ain't no engine anyway.
Since there is no MOM engine on any drawing board the only thing (perhaps) that Airbus could do is a small 'simple' 321 stretch out to 250 economy seats at (Say)29" pitch.And trade this additional weight for range.So it would be a sort of mini 757-300.The only point in doing that is of course if there are new sales to be gained.There are only 50 odd 757-300's so that's not worth it.Are there (I don't know) loads of old 767's being misused on transcon routes?Thats the sort of market that might make such a 322 worth doing.If not then it's in their business interests to sit on their hands and print money with 321NEO sales!

I disagree as this makes no sense. If there is a market big enough to support what Boeing might do and Airbus´s answer, it would make no sense to wait. If Airbus thinks the market above the A321 is not worth the effort, they must ignore whatever Boeing does. If they think there is a real market to be captured waiting for Boeing makes equally no sense.

Locked.

There is no need to kick a 8-month old thread when we have a more recent thread on the same subject.