Morrow, John D

Welsh, Clement J

English

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RM L51A29 
RESEARCH MEMORANDUM 
FLIGHT INVESTIGATION AT MACH NUMBE RS FROM 0.8 TO 1.5 
OF THE DRAG OF A CANOPY LOCATED AT TWO POSITIONS 
ON A PARABOLIC BODY OF REVOLUTION 
By Clement J. Welsh and John D. Morrow 
Langley Aeronautical Laboratory 
Langley Field, Va. 
NATIONAL ADVISORY COMMITTEE 
FOR AERONAUTICS 
WASHINGTON 
March 15 , 1951 
https://ntrs.nasa.gov/search.jsp?R=19930086698 2020-06-17T13:51:25+00:00Z
1 NACA RM L51A29 
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 
RESEARCH MEMORANDUM 
FLIGHT INVESTIGATION AT MACH NUMBERS FROM 0 . 8 TO 1 . 5 
OF THE DRAG OF A CANOPY LOCATED AT TWO POSITIONS 
ON A PARABOLIC BODY OF REVOLUTION 
By Clement J . Welsh and John D. Morrow 
SUMMARY 
Results of an exploratory free - flight investigation of two drag 
research models equipped with canopies are presented for a Mach number 
r ange of 0 .8 to 1 . 5 . The t wo models differed mainly in that one had the 
leading edge of its canopy located at the 15- percent fuselage station 
and the other had an identical canopy located at the 25-percent fuselage 
station. The canopies were semibodies of revolution distorted to fit the 
contours of the fuselage . The r atio of f r ontal areas of the canopy to 
the fuselage was arproximately 1 :10 . 
The additional drag due to the canopies amounted to about 10 to 
20 percent of the total configuration drag at supersonic speeds . At 
supersonic speeds the more favorable location of the canopy was at the 
rearward station , although at transonic speeds the forward location was 
the more favorable . 
INTRODUCTION 
The National Advisory Committee for Aeronautics is at present con-
ducting test s to determine the drag of practical fuselage shapes at 
transonic and supersonic speeds . One phase of this program, pertaining 
to the effects of nose bluntness on the total drag of a body , was presented 
in reference 1 . In the present paper the drag results of a canopy at 
two body locations are presented . The canopies for both configurations 
were developed from bodies of revolution and were located such that 
their leading edges were at the 15- and 25- percent fuselage stations on 
a body of revolution having a parabolic - a rc profile . The r atio of frontal 
areas of the canopy to the fuselage was approximately 1 : 10. 
2 NACA RM L5lA29 
The tests were conducted at the Pilotless Aircraft Research Station 
at Wallops Island J Va ' J by means of r ocket- propelled models . The tests 
covered a Mach number r ange from 0 . 8 to 1. 5 which corresponds to a 
Reynolds number range from 22 J OOO J OOO to 55 J OOO J OOO based upon the 
fu selage length . 
MODELS AND TESTS 
The general arrangement of the two test models used in this investi-
ga tion is shown in figure 1 and photographs of the models are shown as 
figure 2 . 
The fuselage for both configurations was a parabolic body of revo-
lution having a fineness ratio of 8 .91 . The coordinates of the fu selage 
are shown in table I . The canopies for both configurations were derived 
from a parabolic body of revolution identical to configuration 9 of 
refere nc e 2 J except for an extension of the cut-off base (of the reference 
configuration) to a point and a reduction in scale by a factor of 0 .46 . 
The resulting body had a fineness ratio of 7. 8 with maximum diameter 
located at its 15 . 5 -percent station. The body was then split along its 
longitudinal axis to form a semibody and bent so that the axis of the 
semibody coincided with the contour of the fuselage. The cross sections 
of the bent semibody were then sheared to conform with the circular cross 
sections of the fuselage body . Thi s development of the canopy is shown 
graphically in figure 3 J and the coordinates of the canopies before and 
after distortion are presented in table II. The frontal area of the 
canopy was approximately 10 percent of the frontal area of the fuselage 
body . An identica l body without a canopy was flown in order to determine 
the incremental drag produced by the addition of the canopies. 
The models were propelled by a two-stage system utilizing a 3.25-inch 
Mk . 7 rocket for a sustainer a nd a 5-inch RVAR motor as a booster. Test 
data were obtained and reduced by the methods described in reference 3 . 
The velocity was obtained f rom the CW Doppler velocimeter J a nd the tra-
jectory and atmospheric data from an NACA modified SCR584 radar tracking 
unit combined with radiosonde observations . The drag coefficients 
obtained are based on the frontal area of the ba sic fusela ge (0 .307 sq ft) 
and include fin and interference drag . The estimated errors in the values 
of dra g coefficient are within ±0 . 01 at a Mach number of 1. 00 and ±0 . 005 
at a Mach number of 1 . 4. The estimated errors in Mach number are withi n 
±0 . 01 . 
In figure 4 the average Reynolds number R for the configurations 
tested based on a body length of 5 . 57 feet is plotted against Mach 
number M. 
NACA RM L5lA29 3 
RESULTS 
Total - drag coefficients CD of the two canopy-fuselage configu-
rations tested are plotted against Mach number M and presented in 
f igure 5 along with the drag curve of a configuration having no canopy . 
At the lowest Mach numbers investigated there were no measurable 
differences in the drag of the configurations tested. In the Mach number 
r ange from about 0 . 95 to 1 . 12 the test data indicated that the drag of the 
forward located canopy configuration was less than that of the rearward 
located canopy and was even l e s s than the drag of the bas ic body t hrough 
part of this Mach number range . Although no positive explanation can be 
advanced to account for the re'duction of drag due to adding the fore 
canopy to the basic body, this effect is, however, in agreement with 
that noted in reference 4 . Above M = 1 .05, both canopies caused a 10-
to 20 - percent increase in drag; however, the rearward station tended to 
be the more favorable location at the higher Mach numbers. 
Also shown in figure 5 is an estimated drag curve obta ined from the 
summation of the experimental drag of the fuselage and the drag of an 
isolated canopy for free - stream conditions; the isolated canopy drag was 
assumed equal to one - half of the experimental drag of the scaled-down 
original body (reference 2) from whi ch the canopy was developed. The 
estimated curve has been included to provide a comparison between an 
engineering approximation of the drag of a fuselage-canopy configuration 
and measured values. 
CONCLUDING REMARKS 
An exploratory rocket - powered flight investigation of two drag 
research models equipped with canopies has been conducted in the Mach 
number range from 0 . 8 to 1 . 5 . The models differed mainly in canopy 
locations , one canopy' s leading edge being located at the l5 -percent 
fuselage station and the other at the 25-percent fuselage station . The 
canopies were semibodies of r evolution distorted to fit the contours 
of the fuselage . The ratio of frontal ar eas of the canopy to the fuselage 
was approximately 1 : 10 . 
The addit ional drag due to the canopies amounted to about 10 to 
20 percent of the total configuration drag at supersonic speeds . The 
4 NACA RM L5lA29 
rearward canopy location configuration had the lesser drag at supersonic 
speeds j however , at transonic speeds the forward located canopy configu-
ration had the lesser drag . 
Langley Aeronautical Labor atory 
National Advisor y Committee for Aer onautic s 
Langley Field, Va . 
REFERENCES 
1. Hart, Roger G. : Flight Investigation at Mach Numbers fr om O. S to 1 . 5 
to Deter mine the Effects of Nose Bl untness on the Total -Drag of 
Two Fin-Stabilized Bodies of Revolution . NACA RM L50I OSa, 1950. 
2. Katz, Ellis R.: Flight Investigation at High- Subsonic, Transonic, 
and Supersonic Speeds to Determi ne Zero-Lift Drag of Bodies of 
Revolution Having Fineness Ratio of 6 .04 and Varying Positions 
of Maximum Diameter. NACA RM L9F02, 1949 . 
3. Morrow, John D. , and Katz, Ellis: Flight Investigation at Mach 
Numbers from 0 . 6 to 1 .7 to Determi ne 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 . 
4 . Alexander , Sidney R.: Effect of Wi ndshield Shape of a Pilot's Canopy 
on the Drag of an NACA RM - 2 Drag Research Model in Flight at 
Transonic Speeds . NACA RM LSE04, 1948 . 
NACA RM L5lA29 5 
TABLE I 
66.81 
26.724 
-±-. >< 
~-
T 0 
co 
- Xy N . 
I') 
Ii) 
. 
t--
All dimensions are in inches . 
FUSEIAGE COORDINATES 
XF rF xF r F 
0 0 36 .00 3.64 
2 .54 38 .00 3.58 
4 1.04 40 .00 3.52 
6 1.50 42 .00 3. 44 
8 1. 91 44.00 3. 36 
10 2.28 47 .00 3. 21 
12 2 .61 50 .00 3.04 
14 2·90 53 .00 2.84 
16 3·15 56 .00 2.62 
18 3·35 58 .00 2. 47 
20 3·51 60 .00 2.30 
22 3.63 62 .00 2.12 
24 3·71 64.00 1.93 
27 3·75 66 .00 1. 72 
30 3.74 68 .81 1.64 
33 3·70 ----- -- - -
-
6 NACA RM L5lA29 
TABLE II 
COORDINATES 15-PERCENT CANOPY COORDINATES 25-PERCENT CANOPY 
Fuselage Z Y Station 
Fuselage Z Y Station 
10 .021 0 2.285 16.703 0 3.223 
10. 500 .450 2.818 17.000 .260 3.513 
11.000 .830 3 .282 18.000 · 915 4.375 
12 .000 1 . 365 3· 977 20 .000 1 . 602 5.115 
14.000 1. 705 4. 605 22 .000 1.690 5 · 323 
16 .000 1.781 4.927 24.000 1.685 5.396 
18 .000 1. 640 5 .050 26.000 1 . 620 5. 368 
20 .000 1. 560 5.073 28 .000 1.531 5. 279 
22.000 1.455 5.088 30.000 1.415 5.151 
24 .000 1.344 5 .055 32.000 1.291 5.005 
26 .000 1.182 4. 930 34.000 1 .120 4. 800 
28 .000 1.000 4.748 36.000 
· 925 4. 562 
30 .000 .805 4.541 38 .000 .715 4.298 
32 .000 . 560 4.274 40 .000 . 460 3·979 
34.000 .285 3. 965 42.000 .180 3.624 
35·950 0 3 . 645 43.235 0 3·392 
COORDINATES UNDISTORTED CANOPY 
x r x r 
0 0 8 .170 1.645 
.909 .672 9 .090 1. 615 
1.818 1 .170 12 . 250 1.465 
2.725 1 . 510 16.350 1.176 
3.640 1.680 19.100 .914 
4.540 1.704 22 .000 . 568 
5.450 1.700 24.000 .388 
6 . 350 1.685 26.000 .124 
7 .270 1 . 665 26.267 0 
----------~~-- -
NACA RM L5lA29 
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See t :'IDle II for can(}py coord/notes 
Figure 1.- General arrangement of vehicle showing canopy locations. 
All dimensions are in inches. 
7 
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(a) l 5-percent-canopy location. 
Figure 2 .- Photographs showing general arrangement of canopy-body 
configur ations. 
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NACA RM L5lA29 13 
A 
canopy 
A 
- -- ----
],.5.- or 25-percent station 
Step 1 . (Bending of canopy): Undistorted seroibody (canopy) is bent so 
that the axis of the canopy coincides with the surface of the fuselage 
and such that the radii r remain perpendicular to the axis of the 
distorted canopy. 
Section A-A 
Step 2. (Shearing of cross sections): Cross sections of bent canopy are 
assumed to be circular in a plane perpendicular to the fuselage center 
line and are "sheared" as shown to conform to the curvature of the 
fuselage. 
Figure 3. - Explanation of method of mounting canopy on body. See table II 
for "bent" and undistorted canopy coordinates . 
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Figure 4.- Reynolds number based on body length of 5.57 feet plotted 
against Mach number. 
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M 
1.2 1.3 1.4 
Figure 5.- Total drag coefficients plotted against Mach number for the 
canopy configurations ) and a configuration with no canopy. Also 
plotted are the calculated combined drag coeffici ents of the fuselage 
body plus an assumed isolated canopy. Drag coefficients are based on 
frontal a rea of the fuselage of 0.307 square foot. 
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1.6 
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VI 


Flight Investigation at Mach Numbers from 0.8 to 1.5 of the Drag of a Canopy Located at Two Positions on a Parabolic Body of Revolution

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