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Blended wing bodies can produce more lift by its aerofoil configuration. It has been shown to produce up to a 30% decrease in fuel burn due to its additional lift, compared to a tube and wing plane.

My question is: does this extra lift produce more induced drag? Could this induced drag cancel out the aerodynamic advantage of the lifting fuselage?

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    $\begingroup$ Can you add some links about that claim? $\endgroup$
    – sophit
    Commented May 24 at 4:23

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They don't produce additional lift. Aircraft produce lift equal to weight.

The added lift of a fuselage may reduce the angle of attack required by the wing to achieve lift equal to weight -- but for aircraft in cruise, there is no such thing as 'more lift'.

All lift contributes to induced drag. The induced drag can be determined by looking at the downwash of the wake after the aircraft passes -- it does not care whether that lift came from wing, body, tail, etc.

For induced drag, what matters is

  1. total lift (which equals weight)
  2. span that the lift was created over
  3. the shape of that lift distribution.

So, the best way to reduce induced drag is to reduce weight.

The second best way to reduce induced drag is to increase span.

The third best way to reduce induced drag is to improve the shape of the lift distribution.

Tube & wing aircraft will show some lift deficit at the centerline because the body does not contribute significant lift. Adding some lift to the body can fill that in and consequently improve the lift distribution and thereby reduce induced drag.

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  • $\begingroup$ Thank you. Would it be correct to also say that a blended wing body increases the lift-to-drag ratio compared to a tube and wing, rather than producing "additional lift"? $\endgroup$
    – E. Chao
    Commented May 25 at 6:38
  • $\begingroup$ Done right, that is certainly the hope -- but it is likely that the improvement comes from reduced wetted area (and attendant skin friction drag) by eliminating the fuselage and tail. $\endgroup$ Commented May 25 at 17:08

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