Library › Aircraft design › Ground-effect design ·

Power-augmented ram (PAR)

Name: Power-augmented ram (PAR) dimension sheet
Creator: Xem Studio
License: https://creativecommons.org/licenses/by/4.0/

What is power-augmented ram (PAR) take-off? · Standard part · basis: Design rules and figures from the cited sources; example geometry by Xem Studio

Also called: power augmented ram, par wig, par thrust, ekranoplan takeoff, blown wing ground effect, par engines ekranoplan, wig takeoff hump, air cushion takeoff wig, power augmented ram rc

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

sizes: 8 in table

Notes

PAR aims engine exhaust under the wing so it is trapped by endplates and a deflected flap, forming an air cushion that lifts the craft off the water before it reaches flying speed; near the ground lift comes mainly from that cushion (NASA TM-78793).
In NASA tests, flap deflection beyond about 20 deg dropped the flap trailing edge below the endplates and lost the cushion; trapped efflux cut forward thrust to about two-thirds of fan thrust (NASA TM-78793).
Soviet craft used dedicated PAR engines: Orlyonok had two 10 t PAR engines plus a 16 t cruise turboprop; Kaien-2 reached take-off CLmax 1.9 at 15 deg pitch-up, about four times cruise (Rozhdestvensky).
Used on: Orlyonok, KM (Caspian Sea Monster), Loon, Kaien-2.
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.

Power-augmented ram size chart

parameter	value or range	source
NASA model wing	1 m chord x 2 m span (AR 2), Clark-Y 12%	NASA TM-78793
Fan position	about 0.76 chord ahead of LE (4 exit diameters)	NASA TM-78793
Flap limit for cushion trapping	~20 deg (flap TE meets endplate bottom)	NASA TM-78793
CL with 19 deg nacelle, 10 deg flap, CT 1.6	~3.5 at ~20 deg AoA	NASA TM-78793
Forward thrust with trapped efflux	~2/3 of fan thrust	NASA TM-78793
Test heights	0.08-0.50 spans	NASA TM-78793
Kaien-2 take-off CLmax	1.9 at 15 deg	Rozhdestvensky 2006
Reference build	span 400, chord 200 (1:5 of NASA model), endplates 30	computed

Where the files are

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

NASA Langley / DTNSRDC (Thomas, Paulson & Margason)	Powered Low-Aspect-Ratio Wing in Ground Effect (WIG) Aerodynamic Characteristics, NASA TM-78793 (1979)	web	Publisher's page; dimensions are facts
Progress in Aerospace Sciences (K.V. Rozhdestvensky, 2006)	Wing-in-ground effect vehicles (review)	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

power-augmented-ram-par-wing

power augmented ram: span 400, chord 200 mm, anhedral 0°, endplates 30 mm (scale to your craft)

STEP · STL

Let your AI pull this. Add https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.

Set it up →

Plain text: sheet.txt · JSON: /api/geometry?object=power-augmented-ram-par