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Since the winggrid has a different topology compared to other wing-tip devices, it is essential to classify
it and understand its effects.

Properties Authors
practical limit span_efficiency Zimmer 83 Kroo 95 La Roche 96
parameter h/b compares vertical dimension h of configuration to span b pure geometrical classification criteria mix of geometry and downwash-wake criteria downwash-wake parameters only

vortex-spacing and vortex-core

Spreiter & Sacks



contour/straight planar with nonplanar wake contour

with h/b=0.2

simple wingtips/


nonplanar monoplane endplate


slotted edge/fanned partial nonplanar


open fanlike

with h/b<0.05 for Winggrid

N.A. N.A. closed multiple Winggrid/



with h/b=0.2

N.A. multiplanes/box/strut/

closed, C-Wing


second row explains assessment criteria of the different authors
span efficiency is the efficiency relative to an elliptical wing
N.A. = not available
95 = year of publication



H. Zimmer, The aerodynamic optimization of wings at subsonic speeds and the influence of wingtip design, NASA TM-88534 1987 (translation of dissertation, Stuttgart 83).

Ilan Kroo, John McMasters, Stephen C. Smith, Highly Nonplanar Lifting Systems,  Transportation beyond 2000: technologies needed for engineering design, NASA Langley Research Center, Hampton, VA, September 26-28, 1995.

U. La Roche and S. Palffy, WING-GRID, a Novel Device for Reduction of Induced Drag on Wings, Proceedings ICAS 96, Sorrento, ITALY, September 8-13, 1996.

Back to winggrid

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Updated: 31 January, 2007