Katz, Ellis

Marley, Edward T

Pepper, William B

English

NASA Technical Reports Server

, 
.J ' 
RM L50G31 
RESEARCH MEMORANDUM 
FLIGHT INVESTIGATION AT MACH NUMBERS FROM O.S TO 1.4 
TO DETERMINE THE ZERO - LIFT DRAG OF WINGS 
WITH "M" AND "W" PLAN FORMS 
By Ellis Katz, Edward T . Marley, 
and William B. Pepper 
Langley Aeronautical Laboratory 
Langley Air Force Base , Va. 
NATIONAL ADVISORY COMMITTEE 
FOR AERONAUTICS 
WASHINGTON 
September lS) 1950 
N vember 14 1 6 
https://ntrs.nasa.gov/search.jsp?R=19930086334 2020-06-17T12:39:09+00:00Z
• 
NACA RM L50G31 
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 
RESEARCH MEMORANDUM 
FLIGHT INVESTIGATION AT MACH NUMBERS FROM 0.8 TO 1.4 
TO DETERMINE THE ZERO- LIFT DRAG OF WINGS 
WITH "M" AND "W" PLAN FORMS 
By Ellis Katz, Edward T. Marley, 
and William B. Pepper 
SUMMARY 
The zero- lift drag of two wings, one having 450 sweepforward of the 
inboard panel and 450 sweepback of the outboard panel ("M" Wing) and the 
other having reverse panel sweep ("W" Wing) have been measured in rocket 
model flight tests at Mach numbers from 0.8 to 1 . 4. An M- wing and a 
W-wing with an aspect ratio of 4 and a section thickness of 6 percent 
were flqwn and, in addition, an M- wing with attached nacelles and with 
an aspect ratio of 6 and a section thickness of 9 percent was flown. 
The results were compared with a rectangular and a fully sweptback wing 
and indicated that, in the transonic region, the M- and W- wings had 
greater drag than a sweptback wing and less drag than a roughly comparable 
rectangular wing. At slightly higher speeds (Mach number of 1.25), the 
M- and W- wings had less drag than an unswept wing and the same or less 
drag than the sweptback wing . 
INTRODUCTION 
Analysis of wings which are practical for high-speed flight has 
shown that although swept wings generally have less drag than comparable 
straight Wings, this advantage is offset to some extent by their lower 
structural rigidity. A preliminary study of a wing employing sweepback 
on the outer wing panels and sweepforward on the inner panels (an "M" 
plan form) or vice versa (a "W" plan form) has indicated that such a 
wing might reduce the aerodynamic - center shift resulting from twist due 
to bending which is an unfavorable characteristic of swept wings. 
This paper presents results of rocket model flight tests made to 
determine the zero-lift drag of M- and W-wings through the range of 
transonic speeds. The wings tested had thicknesses of 6 and 9 percent 
/ 
\ 
2 
for aspect r atios of 4 and 6, respectively . 
with the zero- lift drag of stright and swept 
this paper are the r esults of simple flexure 
and on fully sweptback wings . 
NACA RM L50G31 
The results are compared 
wings. Also included in 
tests on the subject wings 
The wing drag presented in this investigation is taken as the 
difference in the total drags of winged and wingless configurations and, 
therefore , includes interference effects. The Reynolds number range of 
the tests is from approximately 2 X 106 to 8 X 106 corresponding to a 
Mach number range from approximately 0 . 8 to 1.4. 
MODELS 
The present test models had wings which are referred to as M, W, 
and sweptback p l a n forms. The M-wing is defined as having a plan form 
such that the outboard wing panels ar e swept back and the inboard panels 
a re swept forward. The W- wing is defined as the reverse of the M plan 
form in tha t the inboard wing panels are swept back and the outboard 
panels are swept forward . The fully sweptback wing is swept back over 
the total span . 
The sweep angle for the present test wings was ±45° referred to 
the 25- percent- chor d l ine . Two types of research configurations are 
reported for the pres ent investigation . The f irst type, shown in 
figure 1, had untapered wings of M and W plan forms, aspect ratio 4, 
and NACA 65-006 airfoil sections (parall el to the plane of symmetry) 
mounted on a pointed cylindrical body with four thin stabilizing f ins. 
The break in the wing plan forms was at 50 percent of the exposed semi-
span . The second type of configuration, shown in figure 2, had wings 
of M and fully sweptback plan forms , aspect ratio 6 , taper ratio 0.6, 
and NACA 65A009 a irfoil sections mounted on a body of curved pr ofile 
with two thin vertical stabiliz i ng fins. The coordinates for the body 
and nacelles a re given in t able I . For the second type of configuration, 
the M- wing had nacell es mounted a t the spanwise location of the break in 
the wing plan form and the sweptback wing was tested with and without an 
identical nacelle at the same spanwise location. The break in the plan 
form of the M-wing was at 34 percent of the exposed semispan. In addi-
tion, a wingless configuration wa s fl own which had four stabilizing fins. 
TESTS 
Two models of each of the nontapered winged configur at ions of aspect 
r atio 4 were successfully test flown and one model of each of the tapered 
winged configurations of aspect r a tio 6 were successfully flown, except 
--~--~-.---
NACA RM L50G3l 
for the wingless configuration for which two models were flown. The 
models were launched at an elevation angle of 700 and propelled to 
supersonic speeds by means of a two- stage rocket propulsion system. 
The data were obtained during the coasting flight (decreasing speed) 
after burnout of the second stage rocket motor. A description of the 
test technique is given in reference 1. 
Flexure tests were performed on the test airfoils and the results 
are presented in the appendix of this paper together with additional 
tests on wings of similar plan forms but of higher aspect ratio. 
The probable inaccuracy in the values of wing drag coefficient 
are approximately ±O.002 except at the extreme ends of the Mach number 
range. The Mach number is believed to be accurate to within ±0.01. 
RESULTS 
The Reynolds number range of the tests is given in figure 3. 
Figure 4 shows the results for the test configurations as total drag 
coefficient CDT (based on wing exposed area) against Mach number M. 
3 
Figure 4(a) refers to the configurations with nontapered test wings of 
aspect ratio 4 and includes also the wingless body drag coefficients 
which have been taken from reference 1. Figure 4(b) refers to the 
configurations with tapered test wings of aspect ratio 6. The wingless 
curve in figure 4(b) represents the drag coefficient of the body with 
two stabilizing fins and has been obtained from the flight data for the 
four-finned wingless configuration by subtracting the measured drag of 
two fins . The data for the sweptback wing without nacelles are included 
to show the magnitude of the nacelle drag. 
The difference in total drag coefficient between the winged and 
wingless configurations is referred to as wing drag coefficient Cnw 
and represents the isolated wing- plus-interference drag. Figure 5 
presents wing drag coefficient against Mach number for the test wings. 
Included in figure 5(a) are the results of free-fall tests for a swept-
back wing (reference 2) and a rectangular wing (reference 3) mounted on 
pointed cylindrical bodies. The reference sweptback wing had no taper, 
an aspect ratio of 5 . 4, 450 sweepback, and NACA 65-series sections 
6.36 percent thick. The rectangular wing had no taper, an aspect ratio 
of 7.6, and NACA 65-series sections 6.00 percent thick. Although the 
reference wings are not exactly comparable to the test M- and W-wings, 
it is believed that differences are small enough to justify a rough 
comparison between the plan fOrmB. Figure 5(b) shows the wing drag 
coefficients for the M-wing and swept wing with nacelles and for the 
swept wing without nacelles. 
4 NACA RM L50G31 
The same general results are noticed for the wings of aspect 
ratio 4 ( f i g. 5 ( a )) as for the wing of aspect ratio 6 ( fig . 5(b)) . Plan-
form var iations appeared to have greatest effect on zero- lift drag at 
transoni c speeds where the M- and W-wings had greater drag than the 
sweptback plan form but less drag than the rectangular plan form . With 
increas i ng Mach number the drag differences between the wings of M, W, 
and sweptback plan forms became less until at M = 1 . 25 the di fferences 
were very small. At transonic speeds the drag of the M- wing was con-
siderably greater than the drag of the W-wing . 
CONCLUSIONS 
The zero- lift drag of wings having "M" and "WI! plan forms has been 
measured in rocket model fl i ght tests at Mach numbers from 0.8 to 1.4. 
The results were compared wi th a rec t angular and a fully sweptback wing 
and the following conclusions were noted: 
1. At transoni c speeds both M- and W- wings had greater drag than 
a sweptback wing and less drag than a roughly comparable rectangular 
wing . 
2 . At t r ansoni c speeds the drag of the M- wing was considerably 
greater than the drag of the W-wing . 
3 . The diffe r ences between the M-wing, the W- wing, and the swept-
back wing were much smaller at Mach numbers above 1. 25 . 
Langley Aer onaut ical Laboratory 
Na t ional Advisory Commi ttee for Aeronautics 
Langley Air Force Base , Va . 
., 
NACA RM L50G31 5 
APPENDIX 
RESULTS OF FLEXURE TESTS 
Little factual data are available with which one may judge the 
relative rigidity of M or Wand fully swept wings . Therefore , simple 
flexure tests were made on both the flight- test wings of aspect ratio 4 
and on a series of M and fully swept wings having rectangular sections . 
These data provide a very rough direct comparison of the relative deflec-
tion under load of the two types of plan forms . 
In the flexure tests of the test wings of aspect ratio 4, measure-
ments were made of the rotation and translation of the airfoil sections 
due to a concentrated load applied at the 35 percent tip chord location 
and due to a pure couple applied at the tip parallel to the plane of 
symmetry. The methods of loading these wings, that is, a couple and a 
concentrated load at the tip on the 35- percent- chord line, are but 
simple and arbitrary loadings and should not be misconstrued to be 
simulated air loads . The results are shown in figure 6 plotted against 
spanwise distance from the model center line -4- The upper two plots b/2 ' 
give the vertical deflection of the 35- percent- chord line due to the 
couple and load and the lower plots show the section twist (measured 
parallel to the plane of symmetry) due to the load and couple. Positive 
values of loads and deflections correspond to bending the wing up and 
positive values of couples and twists correspond to rotating the sections 
such that the leading edge moves down. 
In general, for the present loading conditions, the M- and W- wings 
indicated less twist and deflection for equal loads than did the fully 
swept wing . 
The supplementary tests were made on wings of higher aspect ratios 
(8, 10, and 12) having 12-percent- thick rectangular sections. The load 
was applied at the 50 percent tip chord location and the pure couple 
applied at the tip parallel to the plane of symmetry. The results are 
shown in figure 7 and are presented in the same form as in figure 6. 
The indications are that the deformation of the M- and W- wings was, in 
general, less than that of the sweptback wing . 
J 
6 NACA RM L50G31 
REFERENCES 
1 . Morrow, John D. , and Katz , Ellis : Flight Investigation at Mach 
Numbers from 0.6 to 1.7 to Determine Drag and Base Pressures on 
a Blunt- Trailing-Edge Airfoil and Drag of Diamond and Circular-Arc 
Airfoils at Zero Lift . NACA RM L50E19a, 1950. 
2 . Mathews, Charles W., and Thompson, Jim Rogers: Drag Measurements 
at Transonic Speeds of NACA 65- 009 Airfoils Mounted on a Freely 
Falling Body to Determine the Effects of Sweepback and Aspect 
Ratio. NACA RM L6K08c, 1947 . 
3 . Thompson, Jim Rogers, and Marschner, Bernard W.: Comparative Drag 
Measurements at Transonic Speeds of an NAC A 65- 006 Airfoil and a 
Symmetrical Circular - Arc Airfoil . NACA RM L6J30J 1947. 
NACA RM L'50G'11 7 
T IE 1.- COORDINATES FOR BODY AND NACELLES 
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Body Coordi nat e s 
(in. ) 
X r X r 
0 0.0000 32 .0 3.2504 
.4 .1848 36 .0 3.3144 
.6 .2384 40.0 3.3336 
1.0 .3424 44.0 3.3040 
2. 0 .5776 48. 0 3.2192 
4.0 .9640 52 .0 3.0298 
6.0 1 .2904 56. 0 2.8404 
8.0 1.5768 60.0 2.6511 
12.0 2.0744 64.0 2.4617 
16 .0 2. 4720 66 .70 2.3340 
20 .0 2·7720 
24. 0 2. 9928 
28 .0 3.1464 
Nos e r a dius = 0.040 
Nacell e Coordinates 
( in . ) 
X r X r 
0 0 8 .605 1 .255 
.100 .070 16 .830 1 .255 
·300 .169 17 ·872 1. 237 
.830 .336 18.913 1.195 
1.230 .489 19 ·955 1 .127 
1.830 .622 20 .996 1.029 
2· 330 .744 22 .038 ·909 
2·580 .800 23 .079 .768 
2·958 .876 24 .121 .616 
3.585 .974 24.250 .598 
4.840 1.105 
6.095 1. 190 
7·350 1 .240 
8 
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M-wing configuration 
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W-wing configuration 
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NACA RM L50G31 
(a) General arrangement . All dimensions shown in inches. 
Figure 1. - Test configurations with wings of aspect ratio 4 and NACA 
65- 006 airfoil sections . Wing a r ea (included), 1 . 657 square feet ; wing 
area ( expose d) , 1 . 389 square feet; body frontal area, 0.137 square feet ; 
and fin a r ea (exposed) , 0 .948 square feet. 
A-wing configuration W-wing configuratlor 
(b ) General view. 
Fi gure 1 .- Conc l uded . ~ L-62254 
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(a) General arrangement . All dimensions shown in inches . 
Figure 2 . - Test configurations with wings of aspect ratio 6 and NACA 
65A009 airfoil sections . Sweptback w~nged configuration was also 
tested without nacelles . Wingless configuration was tested with four 
stabilizing fins. Wing area (included) ) 3.878 square feet; wing area 
(exposed)) 3.333 square feet ; body frontal area) 0 .242 square feet ; 
fin area (exposed)) 0 .468 square feet ; and nacelle frontal area) 
0.068 square feet. 

NACA RM L50G31 
(b) General view. 
Figure 2_. - Concluded . 
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Figure 3.- Variation of Reynolds number for typical test models 
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based on wing mean aerodynamic chord . 
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Figure 4.- Total drag coefficient against Mach number . Drag coeffi c i ents 
for a reference wingless configuration are included fo r comparison. 
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are drag coefficients for reference rectangular and sweptback wi ngs 
with NACA 65- series airfoil sections . 
Fi gure 5 .- Wi ng drag coeffi cient against Mach number . 
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NACA 65- 006 a irfoils . Chord length, 0.644 foot. 
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Flight Investigation at Mach Numbers from 0.8 to 1.4 to Determine the Zero-lift Drag of Wings with 'M' and 'W' Plan Forms

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