Engine Nacelle Design


Well-Known Member
Why do aircraft with fuselage-mounted engines typically have longer, more slender nacelles, while wing-mounted engine nacelles usually look more short 'n squat (MD80, Fokker 100, 727, etc. versus newer 737, 757, 767, Airbus, etc.)? The old 737-200 had longer nacelles, but they were ditched with the -300 on up. The CRJ looks like an exception.

Why don't they all use slender nacelles? Or fatter nacelles? Are fatter nacelles better for bypass air on a turbofan? Is there some basic design principle I'm overlooking?
Doesn't have anything to do with the actual nacelle design. It depends on the type of the engine. Wing mounted engines are higher-bypass turbofans, while fuselage mounted engines are lower-bypass.

Do take a look at aircraft such as the 717 or CRJ. They have larger nacelles, as they have higher bypass engines than most fuselage-mounted aircraft.
i think that fusalage mounted engines usauly are not high bypass turbo fan but low bypass turbofans

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Not necessarily.
There just aren't many NEW airliners being made. The ones built recently, DO use high bypass fans. (CRJ, 717, MD90). Most business jets are using high bypass tail mounted engines also. Citation X, Gulfstreams, GEX etc. (The Citation X has a 5:1 bypass ratio)

The length of the nacelle/pylon is based on speed/aerodynamics.