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I am using lower order tools (xflr) for calculation of neutral point and CG location.I can think of modelling the wing in three ways

  1. wing with section inside the fuse missing

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  1. wing with section inside the wings modelled

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  1. section insde the wings removed and the outer wings connected.

enter image description here

What should be the best way to calculate the neutral point and CG?

Mridul
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  • For defining the wing area? – Koyovis Jan 14 '23 at 10:00
  • See here – Peter Kämpf Jan 14 '23 at 16:20
  • If you are literally modeling these choices in XFLR5, they will not only affect the value of Sref (which doesn't really matter, so long as you are consistent) -- but they will also affect the lift distribution. 1) will add erroneous wing tips near the aircraft center -- forcing circulation and lift to drop to zero there. 3) will move the wing tips inboard, reducing the span. 2) will do the best job of modeling the aerodynamics of this system. – Rob McDonald Jan 14 '23 at 20:25
  • At least in pre-design phase, wing is considered as being one single surface extending/prolonging inside the fuselage and the surface "inside" the fuselage counts as wing surface, just a convention. – sophit Jan 15 '23 at 15:22
  • @RobMcDonald Vortex are shed whenever there's a spanwise change in lift distribution. Since at root of a real aircraft the lift will reduce to zero as we approach the fuselage (correct me If I am wrong), large vortex should be shed here. Doesn't case 1 simulate that more closely? – Mridul Jan 16 '23 at 09:18
  • @Mridul Yes there is some dip in the lift distribution near the fuselage, there is usually some amount of lift carryover. Capturing this perfectly is surprisingly difficult -- either computationally or experimentally. The dropoff with a fuselage is generally not as severe as with a gap between the wings. – Rob McDonald Jan 16 '23 at 18:45

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