Vortex lift

[PierreB]

@kitefreak

Recently on the Old Forum, powerful Vortex-Lift was identified as the missing aerodynamic performance parameter measured in Delta Kite flight, that no one at AWEC2019 was able to identify. The NPW is a soft-delta, and gets its “grunt” from exotic vortex-lift. NASA got it right fifty years ago as Rogallo, Barrish, and other power-kite greats did hundreds of developmental prototypes.

19670003842.pdf

As a start there is a quote then a link to a document about the vortex lift. Some explains are welcome. For example, how does the NPW delta wing benefit from the vortex lift?

[kitefreak]

Useful Vortex Lift at high AoA is a primary design virtue of Delta Wings, including the NPW. Not just the grunt-power itself, but a most useful NPW Vortex-Lift capability is maintaining stable flight during wind lulls, when everything else must “claw” desperately to keep flying, or land.

Delta Vortex Lift is a stability design factor, that makes extra Cl power manageable. One may stall a long wing for some vortex lift, but not as deeply, since stable flight requires very responsive and accurate control input, up to actuation saturation.