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0 votes
asked by (12 points)
Lack of vortex modelling creates errors in interesting span loads like the Horten flying wings. Its quite a limit for the interesting designs I am playing with.  Also, having the aerodynamic center remain at the forward 25% in rearward moving wings during a flat spin is a disappointment.  Everyone cares about airline interiors....I care about aerodynamics!  Some different simplified vortex filament models here for example


Please give us the vortex!

1 Answer

0 votes
answered by (866 points)
This is an interesting one! Tomorrow I will try to get that to Austin.
commented by (12 points)
thank you JoeFlyer for the attention. Note that the bell shaped lift distribution on Horten flying wings creates proverse yaw, eliminating the need for rudders or yaw input to coordinate a turn.  This effect exists to some extent even for wings with high taper. Pretty sure that blade element theory does not model this. The proverse yaw is induced from greater upwash toward the tip...this is from the vortex or 3-d flow.  Obviously, getting the adverse and proverse yaw right is pretty important!

True vortex lattice also gives the effect of rear wings on forward wings, say for a close coupled tandem wing layout. I was trying to model a hang glider on such a concept, but probably the blade element wasnt sufficient.  Another important layout that requires the vortex model is canards, where the main wing tip is in the upwash of the canard vortex (outboard of the canard wing span).

Regarding the lift not acting through the 25% chord on a rear moving wing...say a flat spin, Im not sure if the airfoil moment tables account for this aerodynamically speaking in the blade element theory.  It is obviously of utmost importance when looking at post stall behavior, and various aerobatics maneuvers.

Another very welcome advancement would be proper water dynamics so we could make hydrofoils or proper boats. On a related note, it seems that land yachts dont work either...the vectors arent working...only a drag force on wheels.

  If ever there was a time to upgrade the flight model, now is the time!