A320 future wing options


We know Airbus is thinking about the A320 “plus” and the “plusplus”. In this thread I want to think further about the wing options Airbus has.

I can see two viable options here (excluding folding wing tips):


1) Keep the current wing for the smaller/shorter range models and design a new ~42-44m CFRP wing with all fuel in the wing for an A321LR+ and an A322.

As Astuteman and others have pointed out, the weight saving from the CFRP and up to 1.8t for the three ACT's would possibly allow the weight to remain roughly the same despite the larger wing. The reduction in induced drag would then save fuel and add range.


2) Basically use the same idea but stick to the 36m span.

So say you would save 2.5t from the CFRP (very rough guess) and the same 1.8t from the ACT's plus infrastructure you can now load 4.3t more fuel than even the A321LR can (if there were enough fuel volume available in the wings), even with full cargo volume. 4.3t more fuel means 13% more than an A321LR would be able to take with all three ACT's full! That would mean ~4.500nm (marketing range) becomes possible with current engines, MTOW and code C wings.

Basically the smaller models would save 2.5t while the A321LR+ would save 4.3t compared to the LR with three ACT's for the same range. This means all models become more competitive.

The question I would like to put forward is: Would it be possible to design a new CFRP 36m wing with the equivalent of 11.5t more fuel volume (3 x 2.4t/ACT + 4.3t) that still performs as required for the different missions? We are talking 7.000L extra per wing here, so that's quite substantial.



If we look at the advantages and disadvantages of the two options:


Option 1: Existing wing for the smaller/less range models and a new larger wing for the larger/longer legged ones:

Advantages:

- The current wing stays in production, with very low fixed (R&D long paid for) and variable costs (mass production line in place). Probably alu cheaper to produce as well.
- The larger/longer legged models get more capability (range/payload/stretch) with reduced induced drag penalties. Thus more of a viable MoM alternative.

Disadvantages:

- You have two separate wing production lines (could be seen as an advantage as well).
- The larger models won't fit into CODE C gates.
- The smaller/less range models won't benefit from the CFRP weight savings.

Option 2: A new single CFRP 36m wing for all models.

Advantages:

- All models fit into code C gates.
- All models will benefit from the CFRP weight saving.
- Only one wing production line (can be a disadvantage as well).

Disadvantages:

- Less capability (range/payload/stretch) for the larger/longer legged models. Perhaps meaning less competitive in a middle of the market role vs. A 797 (especially in case of a stretch).

Disclaimer: I've left parasitic drag caused by the larger wing out of the equation. We could add this into the discussion if people feel it would make a meaningful difference.

Disclaimer2: I don't claim to be an expert so feel free to correct or add where appropriate.

1) How relevant is it to fit into the C gates, given that this plane would fly between second tier airports that are less crowded and have fewer gates?
How much would it add operational cost if it does not fit in a C gate?
2) If a new larger wing is designed, would it be worthwhile to have another version with the lighter wing to be competitive in shorter ranges? I suppose not that much for Airbus after acquiring CSeries.
3) Assuming that the performance of 321LR is better than expected, does it need more additional fuel in the wings than currently in ACT's? Excessive performance would hurt economy in shorter mission. A new wing may even reduce fuel consumption. I think 4000 nm true range is sufficient (which may be 4500 nm marketing range).

YIMBY wrote:

1) How relevant is it to fit into the C gates, given that this plane would fly between second tier airports that are less crowded and have fewer gates?
How much would it add operational cost if it does not fit in a C gate?

Hard to say for me. I think it would be mainly a flexibility advantage.

2) If a new larger wing is designed, would it be worthwhile to have another version with the lighter wing to be competitive in shorter ranges? I suppose not that much for Airbus after acquiring CSeries.

Indeed, I think there would be only one new wing. For either the whole range or only for the more capable models.

3) Assuming that the performance of 321LR is better than expected, does it need more additional fuel in the wings than currently in ACT's? Excessive performance would hurt economy in shorter mission. A new wing may even reduce fuel consumption. I think 4000 nm true range is sufficient (which may be 4500 nm marketing range).

Each flight you can save the weight and space from a ACT or multiple ACT will become more economical. Also you would want to add some capability for a stretch not only the A321. But yeah possible the volume of one ACT extra in the wing is probably more realistic than adding 14.000L to the wings as if proposed in the opening post.

I predict two wing spans.

The A320 size wing is great for the A320's maximum takeoff weight of 78T. The 97T A321 is too heavy to stay with a code C wingspan.

The A320.5 idea is brilliant. With the improved fuel burn of the NEO you could exchange fuel for payload for a simple stretch of the A320. Keeping the lightweight landing gear and simple wing of the A320 and stretching the fuselage to just over 40m would make a great short range 200 seater.

The orders are currently split 50/50 between the A320 and A321 length, I think this single A320.5 model would cover two thirds of the current A320/21 market in terms of sales. This would become the small short range member of the family.

To cover the upper third longer range sector it needs a bigger wing. This allows it to extend towards the MOM market.

The easy solution is to do what they did with the A340NG to extend the wing. They added a simple tapered wing root extension to the wing. Let's call this the A321X. I estimate a 1m root plug at the thickest part of each wing would provide at least 1 ACT's worth of fuel. The 2metre of extra span puts it into code D gates, so you can now go all out with wingtip extensions to add another few metres. This would increase empty weight by approximately 2T or 4% however lift to drag ratio would improve by at least 10%. Fuel burn would actually reduce slightly due to higher cruising altitude and the no extra thrust would be needed.

The bigger wing means landing and takeoff speeds would also be fractionally slower which would allow a maximum takeoff weight increase to say 102T. They can fit the four wheel MLG that's already available. So with the added fuel from the wingroot extension and the improved lift to drag the paper range would increase to around 4800nm with ACT's. CASM would be similar to the current A321NEO but with extra range you've got more capability. This would be the medium sized long range member of the family.

The A322 can then be stretched based on this bigger wing model. All ACT's would be removed. So by reducing fuel it can allow for the added fuselage weight and passengers. This would have around 3000nm range seat around 270 in max density or a comfortable 250 with reasonable pitch. This can be the best highest CASM short range model.

So three models with 80% commonality.

RJMAZ wrote:

I predict two wing spans.

The A320 size wing is great for the A320's maximum takeoff weight of 78T. The 97T A321 is too heavy to stay with a code C wingspan.

The A320.5 idea is brilliant. With the improved fuel burn of the NEO you could exchange fuel for payload for a simple stretch of the A320. Keeping the lightweight landing gear and simple wing of the A320 and stretching the fuselage to just over 40m would make a great short range 200 seater.

The orders are currently split 50/50 between the A320 and A321 length, I think this single A320.5 model would cover two thirds of the current A320/21 market in terms of sales. This would become the small short range member of the family.

To cover the upper third longer range sector it needs a bigger wing. This allows it to extend towards the MOM market.

The easy solution is to do what they did with the A340NG to extend the wing. They added a simple tapered wing root extension to the wing. Let's call this the A321X. I estimate a 1m root plug at the thickest part of each wing would provide at least 1 ACT's worth of fuel. The 2metre of extra span puts it into code D gates, so you can now go all out with wingtip extensions to add another few metres. This would increase empty weight by approximately 2T or 4% however lift to drag ratio would improve by at least 10%. Fuel burn would actually reduce slightly due to higher cruising altitude and the no extra thrust would be needed.

The bigger wing means landing and takeoff speeds would also be fractionally slower which would allow a maximum takeoff weight increase to say 102T. They can fit the four wheel MLG that's already available. So with the added fuel from the wingroot extension and the improved lift to drag the paper range would increase to around 4800nm with ACT's. CASM would be similar to the current A321NEO but with extra range you've got more capability. This would be the medium sized long range member of the family.

The A322 can then be stretched based on this bigger wing model. All ACT's would be removed. So by reducing fuel it can allow for the added fuselage weight and passengers. This would have around 3000nm range seat around 270 in max density or a comfortable 250 with reasonable pitch. This can be the best highest CASM short range model.

So three models with 80% commonality.

Great post, and this essentially mirrors exactly what we see in the 777X program. Larger overall airframe but LESS thrust, larger wing, greater efficiency (due to the role the stretched airframe now serves). Granted I don't see the future variants of the 320 having less thrust, but I do see them growing with the SAME thrust.

The flexibility of being able to leverage the existing (albeit rare, but already developed/certified) 4-wheel bogie MLG, along with a flexible LD3 / ACT system, high-stance, high-bypass, original design allows for immense flexibility.

It must also be mentioned that the 320 has continually taken flak for inefficient wing fuel storage (though it's proved to be a great LR performer in current guise) - you can be assured that any new wing will cram every OUNCE of fuel into the wings that's possible.

The problem with all the rhetoric about a new wing is $$. The addition of a new wing would result in a very expensive certification process. Why not look at a completely revised 320 replacement. Since the re-winged 320 would have to undertake a certification process it would make sense to redo the entire plane.

RJMAZ wrote:

The A320 size wing is great for the A320's maximum takeoff weight of 78T. The 97T A321 is too heavy to stay with a code C wingspan.

It is not too heavy in the sense that it is already flying and doing quite well as can be seen by the recent 4.750nm equivalent flight. Though I'd agree not the ideal wing for 97t. As always there are trade-offs.

That said if they design a new 2.5t lighter CFRP 36m wing with the 3l extra fuel (one ACT) you already save 3.1t (2.5t + 0.6t) of weight compared to a current A321LR on the same flight.


With staying within 36m you're more dependant on future SFC improvements. With a new larger wing you can more aggressively tackle the MoM.

RJMAZ wrote:

I predict two wing spans.

Good post. A few topline thoughts:

• I've always thought Airbus could dominate the MAX by doing an A320.5 and A322. So why not? Maybe the duopoly dynamic works best when neither A nor B dominates the NB market. Killing the MAX would provoke an earlier Boeing NSA, which would provoke a more expensive Airbus response. This is like nuclear war: nobody wins if both OEM's spend $billions trying to kill each other off; it's better to agree to fight smaller wars at the margins of a roughly-equal duopoly (like fighting in Vietnam and Korea but never in USSR or USA).
• I doubt that a "wing plug" solution will be better than a new wing. Plugs would increase the root-chord length, requiring extensive body modifications. Unless you're okay with the inner-wing stalling during takeoff/landing, you'd need to redesign the high-lift system. A new CFRP wing will be lighter, have lower mx costs, and could use the current root chord (higher AR).
• One huge obstacle for 4,800nm A32X could be cruise mach number. A new wing could be built for .85M cruise, but the A320's nose/tail fineness is very low and you might hit drag divergence over the fuselage well short of .85M. Surely Airbus knows the answer to this quandry; it's just something for us to keep in mind.

The need for ACT's is proof that the current wing is too small for the A321 length. The A320 length doesn't require ACT's because the wing size and wing fuel capacity size is perfectly matched. The A321NEO has only just entered service and is selling so well. A new carbon wing is premature

The reason the wing root extension and new tips is the best option:
Lower risk.
Cheaper in the short term.
Quicker to develop to so it can enter service before Boeings NMA.
Easy to produce with the current suppliers.
Solves the wing fuel capacity problem.

Obviously it will be heavier and less efficient than a carbon wing of similar dimensions but it will be a stop gap for 10 years. It allows Airbus to quickly get it done and move engineering resources to a more important area. I can see Airbus needing to response to Boeings NMA. It will launch a cleansheet 8ab in 5 years time and have it enter service within 5 years of Belongs NMA. It will be a lightweight replacement for the A330's original roll where it sold so well. To sit slightly above the Boeing NMA just like the A330 sat above the 767.

A320.5 (with its nice round 200 pax number!)
In terms of market share amongst existing operators I wonder how much is up for grabs?If an airline has gone one way - or the other it's clear is a far far bigger decision that buying a bit of metal.Its a whole long term infrastructure decision.As such I fear an A320.5 will just be selling ones own existing Airbus customers.
On the other hand the A321NEO/A321LR offers new and improved product capability (profit)that Boeing simply cannot match (hence the 797 to stop the very clear rot).Thus this imho is the best area for development.
Since the new fuse is certified for 250 pax (as recently stated by Airbus) then the quickest and cheapest option would be to stretch the fuse a little -to 250 pax and trade the extra weight for range (fuel).Thus creating a continental aircaft with phenomenal economics.
Not only would Boeing have no short term response they would have no long term one either as the 797 is far too much plane to compete.

Beyond this (increased range and capacity)-yes you would need a new wing.But would the resulting aircraft be as good as the projected 797?
You would need a new wing,possibly/probably the new engines certainly a new centre box section and a new MLG.Hmmm nearly a new aircaft without the carbon fuse,twin aisle benefits.A close call imho.

You can put any wing on an A321, giving it a range of 8000NM if required. The question is how to keep it as light, lean and cheap as possible, giving it the payload-range required for a bigger A320 sub series.

A while ago I took a MTOW of 102.7-106t and requirement of 4500NM a rewinged A321 and 4000NM for a stretched variant as a starting point, without ACT's. A ~30% bigger wing fuel capacity would lead to a 10-15% larger span.

Different wing profiles / aspect ratio's might be considered. You don't want to end up overspecifying the aircraft, making it weak on the bulk of flights; <1500NM.