Theory of Wing Sections

Including a Summary of Airfoil Data

Ira H. Abbott, A. E. von Doenhoff

• Editore: Dover Publications
• Anno: 2012
• ISBN:
  9780486134994
• Argomento: Technology & Engineering
• Categoria: Aeronautic & Astronautic Engineering

`Most useful in working with wing sections and methods for using section data to predict wing characteristics . . . much detailed geometric and aerodynamic data.` — Mechanical Engineering
The first edition of this work has been corrected and republished in answer to the continuing demand for a concise compilation of the subsonic aerodynamics characteristics of modern NASA wing sections together with a description of their geometry and associated theory. These wing sections, or their derivatives, continue to be the ones most commonly used for airplanes designed for both subsonic and supersonic speeds, and for helicopter rotor blades, propeller blades, and high performance fans.
Intended to be primarily a reference work for engineers and students, the book devotes over 300 pages to theoretical and experimental considerations. The theoretical treatment progresses from elementary considerations to methods used for the design of NACA low-drag airfoils. Methods and data are presented for using wingsection data to predict wing characteristics, and judiciously selected plots and cross-plots of experimental data are presented for readily useful correlation of certain simplifying assumptions made in the analyses. The chapters on theory of thin wings and airfoils are particularly valuable, as is the complete summary of the NACA's experimental observations and system of constructing families of airfoils. Mathematics has been kept to a minimum, but it is assumed that the reader has a knowledge of differential and integral calculus, and elementary mechanics.
The appendix of over 350 pages contains these tables: Basic Thickness Forms, Mean Lines, Airfoil Ordinates, and Aerodynamic Characteristics of Wing Sections.

CHAPTER 1

THE SIGNIFICANCE OF WING-SECTION CHARACTERISTICS

1.1. Symbols.

A	aspect ratio
An	coefficients of the Fourier series for the span-load distribution
CD	drag coefficient
CDi	induced drag coefficient
CL	lift coefficient
CLmax	maximum lift coefficient
CM	pitching-moment coefficient
CM	pitching-moment coefficient about the aerodynamic center
D	drag
E	Jones^50 edge-velocity factor, equals ratio of the semiperimeter of the plan form of the wing under consideration to the span of the wing
E	a factor (see Fig. 13)
G	a factor (see Fig. 14)
H	a factor (see Fig. 15)
J	a factor (see Fig. 9)
L	lift
La	“additional” loading coefficient
Lb	“basic” loading coefficient
M	pitching moment
S	wing area
V	speed
Xac	longitudinal distance between the aerodynamic center of the root section and the aerodynamic center of the wing, positive to the rear
a	wing lift-curve slope
ae	effective section lift-curve slope, a0/E
a0	section lift-curve slope
ac	aerodynamic center
b	wing span
c	wing chord
	mean geometric chord, S/b
c‘	mean aerodynamic chord
Cd	section drag coefficient
	section induced-drag coefficient
Cl	section lift coefficient
Cla1	local “additional” section lift coefficient for a wing lift coefficient equal to unity
Clb	local “basic” section lift coefficient
Clmax	section maximum lift coefficient
Cm	section-moment coefficient
Cmac	section-moment coefficient about the aerodynamic center
cs	root chord
ct	tip chord
d	section drag
f	a factor (see Fig. 8)
k	a spanwise station
l	section lift
la	“additional” section lift
lb	“basic” section lift
m	section moment
r	an even number of stations used in the Fourier analysis of the span-load distribution
u	a factor (see Fig. 10)
v	a factor (see Fig. 11)
w	a factor (see Fig. 12)
x	projected distance in the plane of symmetry from the wing reference point to the aerodynamic center of the wing section, measured parallel to the chord of the root section, positive to the rear
y	distance along the span
z	projected distance in the plane of symmetry from the wing reference point to the aerodynamic center of the wing section measured perpendicular to the root chord, positive upward
α	angle of attack
αo	section angle of attack
αe	effective angle of attack
αi	angle of downwash
α lo	section angle of attack for zero lift
α l0s	angle of zero lift of the root section
αs	wing angle of attack measured from the chord of the root section
αs(L=0)	angle of attack of the root section for zero lift of the wing
β	angle of sweepback
ε	aerodynamic twist from root to tip
ηm1	multiplier for obtaining the wing characteristics
ηmn	multiplier for obtaining the span-load distribution
θ
λmk	multiplier for obtaining the induced-angle distribution
π	ratio of the circumference of a circle to its diameter
ρ	mass density of air

1.2. The Forces on Wings.

The surfaces that support the aircraft by means of dynamic reaction on the air are called wings. An aircraft may have several wings which may either be fixed with respect to the fuselage or have any of several motions as in the case of helicopters or ornithopters. Regardless of the type of lifting surface, its aerodynamic characteris...