Some early experimental results from a combined experimental and analytical study being conducted at NASA-Langley of the transonic flutter characterisitics of a generic arrow wing configuration are presented. The planned study includes the parametric variation of a variety of structural and geometric characteristics. Presented here are flutter results of the basic arrow wing, for the basic wing with the addition of two simulated lower-surface-mounted engine nacelles, and for the basic wing with the addition of both the fin and the engine nacelles

Cazier, F. W., Jr.

Cole, Stanley R.

Durham, Michael H.

Keller, Donald F.

Parker, Ellen C.

Wilkie, W. Keats

English

NASA Technical Reports Server

NASA-TM- 100608 1988001 6060 
NASA Technical Memorandum 100608 
Parametric Flutter Studies of an Arrow-Wing 
Configuration - Some Early Results 
Michael H. Durham, Stanley R. Cole, F. W. Cazier, Jr., 
Donald F. Keller, Ellen C. Parker, W. Keats Wilkie, and 
Robert V. Doggett, Jr. 
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June 1988 
National Aeronauth and 
Space Administration 
Langley Research Center 
Hampton, Virginia 23665 
https://ntrs.nasa.gov/search.jsp?R=19880016060 2020-03-20T06:40:36+00:00Z
SUMMARY 
Some early experimental results from a combined experimental and 
analytical study being conducted at the NASA-Langley Research Center of 
the transonic flutter characteristics of a generic arrow-wing 
configuration are presented. The planned study includes the parametric 
variation of a variety of structural and geometric characteristics. 
Presented here are flutter results for the basic arrow wing, for the basic 
wing with the addition of an upper-surface-mounted fin, for the basic 
wing with the addition of two simulated lower-surface-mounted engine 
nacelles, and for the basic wing with the addition of both the fin and the 
engine nacelles. 
INTRODUCTION 
For a number of years researchers have been studying the flutter 
characteristics of supersonic transport-type configurations. Two 
illustrative examples of this research are references 1 and 2. The 
material presented in this report are some early results from a study 
currently underway at the NASA Langley Research Center aimed at 
furthering the understanding of the transonic flutter characteristics of 
supersonic cruise aircraft. For the most part this paper presents the 
figures used by the most junior author in a presentation given at the fall 
1987 meeting of the Aerospace Flutter and Dynamics Council. The data 
are presented here with a minimum of connecting narrative. This report 
may be thought of as the early release of recent research results in the 
interest of rapid technology transfer from Government researchers to the 
outside technical community pending the preparation and release of a 
more comprehensive report. 
The flutter research study that is underway consists of determining 
the effects of several parameters (See fig. 1 .) on the transonic flutter 
characteristics of , a  generic arrow-wing design representative of a 
supersonic cruise airplane. Presented in this paper are some results 
obtained from varying the four parameters shown in figure 2. It should be 
pointed out that the planned study when completed will include a more 
extensive investigation of the effects of the four parameters discussed 
herein. 
A photograph of the basic arrow-wing configuration is shown in figure 3. 
The semi-span wing had a root chord of 91.3 inches and a semispan of 35.1 
inches. The planform geometry was very similar to that of the models 
described in reference 2. The model structure consisted of an aluminum alloy 
plate (See fig. 4.) which was covered with end-grain balsa wood to provide the 
desired parabolic arc airfoil section. Cutouts in the plate were used to 
simulate an arrangement of spars and ribs. Four different configurations were 
tested, namely, the basic arrow wing, the basic wing with the addition of an 
upper-surface-mounted fin, the basic wing with the addition of two simulated 
lower-surface-mounted engine nacelles, and the basic wing with the addition 
of both the fin and the engine nacelles. The models were instrumented with 
resistance-wire strain gage bridges and accelerometers for measuring 
dynamic response. Measured natural frequencies for all four model 
configurations are presented in figure 5. Node lines are presented in figure 6 
for the basic wing and the wing-with-fin-and-nacelles configurations. Note 
that in the frequency range shown, the two "with nacelles" configurations have 
an additional mode, labeled mode 2A in the figures. 
WIND-TUNNEL TESTS 
The wind-tunnel tests were conducted in the Langley Transonic 
Dynamics Tunnel (TDT). This wind-tunnel is used almost exclusively for 
aeroelastic testing. It is of the single return type and speed and stagnation 
pressure are continuously controllable over a range of Mach numbers from near 
zero to 1.2 and of pressures from near vacuum to about one atmosphere. Either 
air or Freon-121 can be used as the test medium. Freon was used for the 
present test. 
A photograph of the basic wing model mounted in the wind-tunnel is 
presented in figure 7. The model was clamped to a fixture using the two tabs 
(See figs. 3 and 4.) which extended from the root of the aluminum plate. The 
fixture was inturn attached to a remotely controlled turntable on the wall so 
that the angle of attack could be changed during testing. The fixture was 
covered with a streamlined fairing. The widths of the fixture and fairing were 
such that the root chord of the model was outside the wind-tunnel wall 
boundary layer. 
-------------- 
1 Freon is registered trademark of E. I duPont de Nemours and Co., Inc. 
PRESENTATION OF RESULTS 
The basic flutter results are presented in figures 8 thru 11 as the 
variation of flutter dynamic pressure with Mach number. The basic wing 
data are in figure 8; the wing-with-fin data are in figure 9; the wing- 
with-nacelles data are in figure 10; the wing with-fin-and-nacelles data 
are in figure 11. These flutter broundaries are all presented in figure 12 
to facilitate comparisons. The curves in figure 12 are repeats of the 
curves that were faired through the data points in figures 8 thru 11. The 
shapes of these flutter boundaries are similar to those that have been 
observed by many investigators previously for a variety of different 
configurations, namely, a decrease in flutter dynamic pressure with 
increasing Mach number to a minimum value near M=1.0 followed by an 
increase in dynamic pressure with increasing Mach number. These data 
show that the addition of the fin to the basic wing increased the flutter 
dynamic pressure. Near M=1.0 the flutter dynamic pressure for both "with- 
nacelles" configurations is lower than that of the basic wing. At lower 
Mach numbers, say M=0.80, the with-nacelles configurations have a higher 
flutter dynamic pressure than does the basic wing. It should be pointed 
out that some data obtained subsequent to that presented here on a 
similar basic wing configuration show a higher level of flutter dynamic 
pressure, about the same level as the present wing-with-fin case. These 
data would lead one to conclude that the addition of the fin has little 
effect on the flutter dynamic pressure and that the addition of the 
simulated engine nacelles results in a lower flutter dynamic pressure 
throughout the Mach number range shown here. The reasons for the 
different levels of dynamic pressure for similar (designed to be identical, 
but, of course, actually slightly different) model wings is under study. 
The variation of flutter frequency with Mach number is presented in 
figure 13 for all four configurations. The flutter frequencies for the two 
with-nacelles configurations are similar and lower than the frequencies 
for the other two configurations. The frequencies of the wing-with-fin 
configuration are lower than the frequencies for the basic wing. 
Some effect of angle of attack, lift, on the flutter of the basic wing 
and the wing-with-fin-and-nacelles configuration are presented in 
figures 14 and 15, respectively, as the variation of flutter dynamic 
pressure with Mach number. In both instances, increasing the angle of 
attack reduced the flutter dynamic pressure. 
CONCLUDING REMARKS 
Some experimental flutter results for a generic arrow-wing flutter 
model with and without a vertical fin and with and without two 
simulated engine nacelles have been presented. These data are some early 
results from a larger program aimed at providing a better understanding 
of the aeroelastic characteristics of supersonic cruise airplane 
configurations. 
REFERENCES 
1. Wykes, J. H.; Sweet, H. R.; Joseph, J. A.; and Hodson, C. H.: Commercial 
Supersonic Transport Flutter Studies. ASD-TRD-63-818, 1964. 
2. Doggett, Robert V., Jr.; and Ricketts, Rodney H.: Effects of Angle of 
Attack and Vertical Fin on Transonic Flutter Characteristics of an 
Arrow-Wing Configuration. NASA TM-81914, 1980. 
STRUCTURAL ARRANGEMENT - WlNG TIP REGION 
MASS DISTRIBUTION - WlNG TIP REGION 
GEOMETRY - WlNG TIP REGION 
FUEL LOADING 
UPPER SURFACE MOUNTED WlNG FIN 
- ONIOFF 
- STIFFNESS 
- MASS EQUIVALENT 
ENGINE NACELLES - ONIOFF 
ANGLE OF ATTACK (LIFT) 
Figure 1 .- Overall study parameters. 
ONE STRUCTURAL ARRANGEMENT - WlNG TIP REGION 
UPPER SURFACE MOUNTED WlNG FIN ONIOFF 
ENGINE NACELLES - ONlOFF 
ANGLE OF ATTACK (LIFT) 
Figure 2.- Parameters discussed in this paper. 
Figure 3. - Photograph of arrow-wing model wing. 
Figure 4. - Photograph of plate structure. 
WISG ASD FIN AND SACELU S 
WISI; ASD 'ACELLES 
WTSG AND I1N 
\ I / 
MODE 
Figure 5. - Measured natural frequencies. 
WlNG ALONE 
WlNG WITH FIN AND NACELLES 
MODE 3 
Figure 6. - Measured node lines. 
Figure 7. - Photograph of arrow wing model mounted in wind tunnel. 
DY NA!'lAIC 
PRESSURE, 
PSF 
183 
160 
140 
120 
inn 
0.50 0.60 0.70 o.ao 0.90 I .oo 1.10 1.20 
MACH NUMBER 
Figure 8. - Variation of flutter dynamic pressure with Mach number for 
basic wing configuration. 
DYNAMIC 
PRESSURE, 160 
PSF 
100 
0.50 0.60 0.70 0.80 0.90 1 .OO 1-10 1.20 
MACH NUMBER 
Figure 9. - Variation of flutter dynamic pressure with Mach number for 
wing-with-fin configuration. 
DYNAMIC 
PRESSURE. 160 
PSF 
100 
0.50 0.60 0.70 0.80 0.90 1 .OO 1.79 1.20 
MACH NUMBER 
Figure 10. - Variation of flutter dynamic pressure with Mach number for 
wing-with-nacelles configuration. 
DYNAMIC 
PRESSURE, 160 
PSF 
100 
0.50 0.60 0.70 0.80 0.90 1 .OO 1 - 1 0  1.20 
MACH NUMBER 
Figure 11. - Variation of flutter dynamic pressure with Mach number for 
wing-with-fin-and-nacelles configuration. 
DYNAMIC 
PRESSURE, 
PSF 
0.50 0.60 0.70 0.80 0.90 1 .OO 1.10 1.20 
MACH NUMBER 
Figure 12. - Comparison of variation of flutter dynamic pressure with 
Mach number for all four configurations. 
FREQUENCY, 
HZ 
0y50 0.60 0.70 0.80 0.90 1.00 '1.10 1.2C 
MACH NUMBER 
Figure 13. - Comparison of variation of flutter frequency with Mach 
number for all four configurations. 
PRESSURE, 
PSF 
r" 
7 - 7 .  
i 1 . 3 u  C.6C 0.70 6.60 il.90 7 .OG 1.10 i .20 
MACH NUMBER 
Figure 14. - Effects of angle of attack on flutter dynamic pressure for 
basic wing configuration. 
DYNAMIC 
PRESSURE, 163  
PSF 
Figure 15. - Effects of angle of attack on flutter dynamic pressure for 
wing-with-fin-and-nacelles configuration. 
NASA FORM 1628 OCT 86 
N/\SA 
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4 1 . 1  1 .  ~VIU-r -..I, 1 1 , ~ t  
Report Documentation Page 
1. Report No. 
NASA TM- 100608 
.--- 
2. Government Accession No. 
- -. 
3. Recipient's Catalog No. 
4.  Tttle and Subtitle 
Parametr ic F l u t t e r  Studies o f  an Arrow-Wing 
Conf igura t ion  - Some E a r l y  Resul ts  
7. Authorls) Michael H. Durham, Stanley R. Cole, F. W. Cazier, 
Jr. ,  Donald F. K e l l e r ,  E l l e n  C. Parker, W. Keats Wi lk ie ,  
and Robert V. Doggett, Jr. 
-- 
9. Performing Organization Name and Address 
NASA Langely Research Center 
Hampton, VA 23665-5225 
' 12. spon;oring Agency Name and Address 
Nat iona l  Aeronaut ics and Space Admin i s t ra t i on  
Washington, DC 20546-0001 
15. Supplementary Notes 
5. Report Date 
June 1988 
6.  Performing Organization Code 
8. Performing Organization Report No. 
lo .  Work Unit NO. 
505-63-21-02 
11. Contract or Grant No. 
13. Type of Report and Period Covered 
Technical  Memorandum 
14. Sponsoring bgency Code 
This  r e p o r t  i s  based on m a t e r i a l  presented a t  a meeting o f  t h e  Aerospace F l u t t e r  
and Dynamics Counci l ,  Las Vegas, NV, Oct. 28-30, 1987. E l l e n  C. Parker i s  an 
employee of PRC-Kentron, Inc. W. Keats W i l k i e  i s  a U. S. Army c i v i l  s e r v i c e  
employee assigned t o  t h e  Aerost ructures D i rec to ra te ,  USAARTA-AVSCOM. H is  
p a r t i c i p a t i o n  i n  t h i s  work was p a r t  o f  a deve lo~menta l  t r a i n i n q  assiqnment. 
16. Abstract 
Some e a r l y  experimental  r e s u l t s  from a combined experimental  and a n a l y t i c a l  
study being conducted a t  NASA-Langely Research Center o f  t h e  t ranson i c  f l u t t e r  
c h a r a c t e r i s t i c s  o f  a gener ic  arrow win9 c o n f i g u r a t i o n  a r e  presented. The planned 
study inc ludes  t h e  parametr ic  v a r i a t i o n  o f  a v a r i e t y  o f  s t r u c t u r a l  and geometr ic 
c h a r a c t e r i s t i c s .  Presented here a r e  f l u t t e r  r e s u l t s  f o r  t h e  bas i c  arrow wing, 
f o r  t h e  bas ic  wing w i t h  t h e  a d d i t i o n  o f  an upper-surface-mounted f i n ,  f o r  t h e  
bas ic  wing w i t h  t h e  a d d i t i o n  o f  two s imulated lower-surface-mounted engine 
nace l les ,  and f o r  t h e  bas ic  wing w i t h  t h e  a d d i t i o n  o f  bo th  t h e  f i n  and t h e  engine 
nacel 1 es. 
17. Key Words (Suggested by Authorlsll 
F l u t t e r  
Arrow wings 
Transonic Speeds 
Aeroel a s t i c i t y  
18. Distribution Statement 
U n c l a s s i f i e d  - Unl i m i  t e d  
Subject  Category 02 
22. Price 
A02 
21. No. of pages 
20 
19. Security Classif. (of thts report) 
U n c l a s s i f i e d  
20. Security Classif. (of this page) 
U n c l a s s i f i e d  


Parametric flutter studies of an arrow-wing configuration: Some early results

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