Blog

Jan 02, 2024

Bjorn’s Corner: New aircraft technologies. Part 11. Airframe.

Hello keesje, I believe that any contender for 737/A32X replacement that

Hello keesje,

I believe that any contender for 737/A32X replacement that requires code D (767/A310) gates, taxiways and runways, will be at a massive disadvantage to contenders that can use code C gates. To be a serious contender, I believe that the stretched A321 that you propose would need folding wings to allow it to use code C gates. Without folding wings, it would largely be limited to use on flights that currently use code D gates at airports with taxiways and runways wide enough for code D aircraft. Code C gates far outnumber code D gates, and airports with taxiways and runways designed to accommodate code C aircraft far outnumber those designed to accommodate code D aircraft.

The problem is not just gates, it is also taxiway and runway spacing and widths. For instance, the FAA requires a runway width of 100 ft for wingspans of 24 to 36 m (ICAO code C/FAA Type III) and 150 ft for wingspans of 36 to 52 m (ICAO code D/FAA Type IV, i.e. 767/A310). There are many airports served by 737/A32X type aircraft that have 100 ft wide runways that would have to be widened to 150 ft to accommodate code C/Type IV wingspans. Widening runways is not cheap. Widening a runway and then having to relocate taxiways to allow adequate spacing between the runway edge and taxiway is even more expensive. Move the terminal building to allow adequate clearance between relocated taxiways and the tails of parked aircraft is even more expansive. Enlarging the terminal building to avoid having to reduce the number of gates to allow for larger spacing between gates due to increased wingspans is even more expensive.

This is why Boeing's TBW studies have included folding wings to allow the aircraft to use airports that have been designed for 737/A32X type aircraft (ICAO code C/FAA Type 3).

"The design was presented at the January 2019 AIAA conference and the wing folds outboard of the truss to use airport gates for the 118 ft (36 m)-span 737.[3] (ICAO aerodrome code C)."

https://en.wikipedia.org/wiki/Boeing_Truss-Braced_Wing

http://www.condellpark.com/bear/faacateg_m.htm