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Ground effect: height/chord ratio (ram / chord-dominated regime)

Name: Ground effect: height/chord ratio (ram / chord-dominated regime) dimension sheet
Creator: Xem Studio
License: https://creativecommons.org/licenses/by/4.0/

What height-to-chord ratio do WIG craft fly at? · Standard part · basis: Design rules and figures from the cited sources; example geometry by Xem Studio

Also called: ground effect height chord ratio, h/c ratio wig, extreme ground effect, ram effect wing, chord dominated ground effect, wig cruise height, ekranoplan flight height, ground effect lift to drag, wig l/d

Exact dimensions. True size, with no printing tolerance added.

sizes: 7 in table

Notes

Rozhdestvensky defines extreme ground effect as clearances of 10% of the main wing chord or less, distinguishing chord-dominated ground effect (flow stagnation under the wing) from span-dominated (induced-drag reduction).
Moore et al. split ram effect (h/c <= 10%) from normal ground effect, and a review concludes rectangular wings are most effective within 15% of chord (Frontiers 2022 review).
An isolated AR 2-3 wing at about 20% chord clearance reaches L/D of roughly 35-45, but hull, pylons and tail cut that by about 65% to 12-16 for a whole craft (Rozhdestvensky, citing Kirillovykh).
The file is a reference example built by Xem Studio from the numbers above. Sizes the sources do not fix are illustrative; scale the example to your own vehicle.

Ground effect: height/chord ratio size chart

parameter	value or range	source
Extreme ground effect	h <= 10% chord	Rozhdestvensky 2006
Ram effect regime	h/c <= 10%	Frontiers 2022 (Moore et al.)
Most effective (rectangular wings)	within 15% chord	Frontiers 2022
Isolated wing L/D, AR 2-3 at 20% c	35-45	Rozhdestvensky (Kirillovykh)
Whole-vehicle L/D after integration	12-16 (losses: hull ~40%, pylons ~15%, tail ~5%)	Rozhdestvensky
Proposed GE-zone definition	height where lift is ~30% above free-flight value	Rozhdestvensky
Reference build	span 600, chord 300	computed (AR 2)

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

Progress in Aerospace Sciences (K.V. Rozhdestvensky, 2006)	Wing-in-ground effect vehicles (review)	web	Publisher's page; dimensions are facts
Frontiers in Aerospace Engineering (2022)	Review of ground-effect experiments on rectangular, reverse-delta and delta wings	web	Publisher's page; dimensions are facts
NASA Langley (Fink & Lastinger)	Aerodynamic Characteristics of Low-Aspect-Ratio Wings in Close Proximity to the Ground, NASA TN D-926 (1961)	web	Publisher's page; dimensions are facts

Free files

★ Free files 1 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json

ground-effect-height-chord-ratio-wing

endplated wing: span 600, chord 300 mm, anhedral 0°, endplates 30 mm (scale to your craft)

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Plain text: sheet.txt · JSON: /api/geometry?object=ground-effect-height-chord-ratio