The A310 wing, misjudged market and a missed opportunity.
I want to again call focus on the strategic missed opportunity for Airbus in the product placement of the A310 (and A300) and the subsequent sizing of the A310’s updated wing.
I actually think the A310 wing was sized perfectly. An aircraft wing is sized for a combination of MTOW but also average stage length. The MTOW is an obvious factor, the higher the MTOW the bigger the wing.
Stage length is interesting. An aircraft optimised for long haul wants a slightly larger wing which can then use lower thrust engines. The empty weight increases but fuel burn reduces. An aircraft optimised for short haul wants a smaller wing with lower empty weight but higher thrust engines to compensate.
This means if we fix the wing size, the A310 wing is sized perfectly for a 150t MTOW long haul frame but also sized perfectly for a 170t MTOW short haul frame. The short haul frame then needs extra thrust.
Another common design link is when an aircraft is stretched the range reduces if the MTOW remains constant. So a stretch turns an aircraft from a long range frame to a medium haul frame for example the 787-9 to 787-10.
Linking all of this together means stretching the A310 frame slightly moves it from a medium/long range optimised frame to a short/medium optimised frame. So the MTOW can increase while keeping the same smaller wing. This means the A310 is still good for a A300 length short haul optimised frame.
The idea that the A310 wing was too small for the short haul A300 is wrong. The area might be smaller but wingspan is the biggest factor for lift and they are similar.
In summary Airbus could have fitted the A310 wing to heavier shorter ranged A300 length aircraft and had improved optimisation.
IMO, the wing of the A310 did well. The wing was sized to the size of the frame. The drag of a wing depends not only on the AR, but also on other design factors, like for example the profile. That was for the A310 a supercritical profile, reducing drag.
I agree the A310 wing is perfect for the frame. I think it was the short stubby fuselage that caused it to end production early. A short cabin length to fuselage length ratio ate into valuable percentage points of efficiency.
A simple stretch of the A310-300 from the 46.66m to somewhere between the length of the A300 of 54.08m would have fixed that ratio.
The PW4000 has a bypass ratio of 4.8:1 94inch fan.
The CF6-80C2 has a bypass ratio of 5:1 93inch fan.
The Trent 500 has a 7.5:1 bypass ratio with 97inch fan. It entered service in 2000. Perfect size, perfect weight and perfect timing for a short/medium range A310/A300 replacement to sit well below the A330 in size and capability.
Fuel burn estimates with the Trent 500 would have increased range of the A310-300 from 5,150nm to around 5,500nm with the same 164t MTOW
I would think the A310 wing combined with the Trent 500 engines could have been fitted on the longer A300 fuselage length. Compared to the A300-600R it would have had greater range, lower empty weight and improved fuel burn. The smaller A310 wing on the A300 would have helped keep distance from the A33 by making it optimised for shorter stage lengths.