Boeing have said a few times that they were considering two different fuselage cross sections for Y1. A.netters have speculated that meant different cabin widths to accommodate a different number of seats per row in Y e.g. 5 abreast vs. 6 abreast vs. 7 abreast. The more I think about it, the more I think Boeing may have something different in mind.
Seven abreast seating means 2-3-2 (3-4 would be illegal) so less than 7/9 (aisles are wider than Y seats) or about 75% of the cabin width would be available for seating. With 3-3 seating, nearly 6/7 or about 85% of the cabin width is available for seating. I believe Boeing could develop two different fuselage cross sections for Y1 both with 3-3 seating. Why?
There are two rather different markets. One market is for a 150-220 seat airline with very low CASM and range of 2000 to 2500nm. Think WN. The other market is for a 200-300 seat airliner with range of 5000nm to open up new transoceanic city pairs. One could think of these as replacements for the B737 and B757 respectively.
The smaller Y1 (B737RS) would have:
- smaller wings, with less fuel capacity
- a much lower MTOW, therefore 2-wheel main bogeys
- a cargo hold sized for A320-size cans
The larger Y1 would have
- larger wings, with greater fuel capacity, for B-market range
- a much higher MTOW, therefore 4-wheel main bogeys
- a cargo hold sized for single-file LD3s
Both Y1s could share:
- a common cockpit, with a common type certification
- common tail surfaces, though the empenage would have to differ
- cabin interior, if the small Y1 is circular and the large Y1 is a double-bubble
I see each in 2 or 3 different (possibly overlapping lengths).
What else could be common?