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2

Yes, that is typical for high bypass ratio (HBPR) turbofans. But why? Because the entry impulse goes up while the exit impulse stays roughly constant. Thrust is the difference between both, derived over time. The moving engine needs to slow down the airflow for combustion to take place, and then needs to accelerate the air by more than it has been ...


23

Your concerns about heavy flaps are well founded. The designers try to get away with as few high-lift devices as they can afford to. But not fewer! If you observe the trend over the years, flaps became more complex with every new airliner generation, starting from simple split flaps in the 1930s to triple-slotted flaps on the Boeing 747 in the late Sixties. ...


11

The questioner seems to have noted that the basic wing with flaps retracted provides a high ratio of L/D (or Cl/Cd). Where L denotes lift, Cl denotes lift coefficient, D denotes drag, etc. We can certainly scale up the basic unflapped wing to provide as low a landing speed as we wish, although landing will be tricky due to the flat glide path. Flaps help ...


13

Climb to cruise burns fuel. Adding additional drag burns fuel. Adding retractable mechanisms adds weight that burns fuel. More drag, even at higher cruise altitudes, requires larger engines for the same cruise speed. Larger engines burn more fuel (despite increases in modern engine fuel efficiency). Retracting high-lift, high drag devices reduces fuel burn ...


44

When flaps are retracted they do nothing, which is the whole point. The byproduct of lift is drag, a larger wing will create more lift, but more drag as well. More drag equals a slower cruising speed, or bigger engines to power past the drag along with higher fuel consumption. Flaps let airplanes cruise faster by getting out of the way.


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