The MC-21-310 is a Russian medium-haul airliner that directly competes with the A320neo and Boeing 737 MAX. And one of its key differences is not visible on the wing, but in the fuselage cross-section: the MC-21's fuselage is wider than both competitors'.
"Pervy Tekhnichesky" figured out what advantages the MC-21-310 gained thanks to the development of domestic engineers.
Every centimeter counts
First, the dry figures: the MC-21's fuselage diameter is 4.06 meters. The A320neo's is 3.95 meters. The 737 MAX's is 3.76 meters.
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The difference with the A320neo is about 11 centimeters, with the 737 MAX it's about 30 centimeters. At first glance, it's not much, but on the scale of the cabin, it changes the layout.
Cramped and resentful - that's Boeing
A larger diameter allows for wider seats - 46–48 centimeters instead of 43–45 for competitors. Or to leave a wider aisle between rows. Or to make luggage racks larger in volume.
For the passenger, these are not abstractions. In the narrow fuselage of the 737 MAX, with a 3+3 layout, the aisle is so compressed that the flight attendant's cart barely fits. In the MC-21, due to the diameter, this gap is larger.
A penny saved is a penny earned, but a ruble spent on transport
A fuselage with a large area has more skin, which means its mass increases. In addition, a pressurized section of a larger volume requires more effort to maintain pressure. The air resistance of a fuselage with a larger cross-section is also higher.
This drawback is compensated by two features:* a composite wing, which is lighter than metal and provides a smoother surface;* the PD-14 engine, designed to achieve high efficiency.A wide fuselage is not just an advantage, but a solution that comes at a cost in other aspects.
As we can see, the MC-21 is not trying to be lighter than its competitors. It is trying to be more comfortable for the passenger - due to the cabin width. And this is a conscious choice: in the class of medium-haul airliners, comfort is becoming as much an argument as fuel consumption.