Vortex lattice is used to describe the lifting surface of an arbitrary wing planform in steady potential subsonic compressible flow in computer program which calculates wing aerodynamic characteristics. Estimates of flow field characteristics in the vicinity of a lifting wing can also be programmed

Lamar, J. E.

Margason, R. J.

English

NASA Technical Reports Server

December 1967	 Brief 67-10666 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
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Computer Program Calculates Wing Aerodynamic Characteristics for 
Fixed Wings with Dihedral and Variable-Sweep Wings at Subsonic Speeds 
This program uses a vortex lattice to describe the 
lifting surface of an arbitrary wing planform in steady 
potential subsonic compressible flow. The following 
aerodynamic characteristics are computed: CL, CL 
at a=0, at CL= 0, Yp, aCm/aCL, Cm., CD/C2L, 
spanwise distribution of additional wing loading, 
spanwise distribution of wing loading due to twist and 
camber, spanwise distribution of basic wing loading, 
and spanwise distribution of wing loading at a spe-
cific lift coefficient combining basic and additional 
loading. Punched card output is also provided for use 
as input to a computer program which estimates the 
flow field characteristics in the vicinity of a lifting 
wing at subsonic speeds. 
The procedure used in this program is divided 
into three parts. The first part computes the geometry 
required to represent the wing planform by a system 
of horseshoe vortices and is divided into three sec-
tions. In the first section, group one of the input data 
(a description of the wing planform) is read and 
checked by the program. The second section reads 
group two of the input data and defines the configu-
ration details. Section three defines the horseshoe 
vortex lattice. 
In the second part of the program, the influence 
functions for the downwash and sidewash velocities at 
the control point of each horseshoe vortex are com-
putéd; the matrix constant terms are computed; and 
the matrix Is solved for values which are proportional
to circulation. The matrix is solved twice; the first 
solution uses the matrix constant terms based on the 
local angle of attack caused by twist and/or camber 
on the wing and the second solution uses the matrix 
constant terms for one radian angle of attack and no 
twist or camber. This results in two sets of circulation 
terms; one for twist and camber surface loading and 
one for additional surface loading. 
The third part of the program uses the circulation 
terms (Fn/U) to compute the lift and pitching-mo-
ment data for wings with dihedral; a simplified pro-
cedure is used for zero dihedral wings. Then for both 
situations the final form of the output data is com-
puted and printed. 
Notes: 
1. This program is written in CDC Fortran, version 
2.0 for the CDC 6000 Series Computer with the 
Scope 2.0 operating system and library tape. 
2. Inquiries concerning this program may be made to: 
COSMIC 
Computer Center 
University of Georgia 
Athens, Georgia 30601 
Referene: B67-10666 
Patent status: 
No patent action is contemplated by NASA. 
Source: Richard J. Margason and John E. Lamar 
Langley Research Center 
(LAR- 10191) 
Category 06 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19670000665 2020-03-11T21:38:02+00:00Z


Computer program calculates wing aerodynamic characteristics for fixed wings with dihedral and variable-sweep wings at subsonic speeds

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