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Report on wind-tunnel test of armored pursuit airplane PG-1, type IV (Airplane Section, S. & A. Branch)

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Auburn University Libraries 11111111~111111m~
\-. -------.3. .1::7.0.:6: .0.2::5. .8~4804~ o ~ )
M9COOK F'IELD REPORT SERIAL No. 1499
AIR SERVICE INF() MA TION CIRCULAR
(AVIATION)
PUBLISHED BY THE CHIEF OF AIR SERVICE, WASHINGTON, D. C.
May 1, 1921 · No. 166
REPORT ON WIND-TUNNEL TEST OF ARMORED PURSUIT
AIRPLANE PG-1, TYPE IV
(AIRPLANE SECTiON, S. & A. BRANCH)
V
Ralph Brown Draughon
LIBRARY
MAR 28 2013
Non-Depoitory
Auburn University
Prepared by Engineering Division, Air Service
McCook Field, January 31, 1921
•
WASHINGTON
GOVERNMENT PRINTING OFFICE
1921
REPORT ON WIND-TUNNEL TEST OF ARMORED PURSUIT
AIRPLANE PG-1, TYPE IV ..
A model of an armored single-seater pursuit airplane for
ground work, designed by Engineering Division, was
test~d at M. I. T. ,' December, 1920. The usual tests for
forces and moments with various settings of the tail plane
were made. The data is given in the accompanying tables
and figures.
Figure 1 gives an impressioi;i of the external appearance
of the airplane. Figures 2, 3, and 4 give the various lift,
L/D and drag curves, and figures 5, 6, and 7 are vector
diagrams for tail settings of + 2°, 0°, and -2°, respectively .
Settings of + 2° and 0° give unstable arrangements.
whereas a setting of -2° gives a condition .of shbility
which is satisfactory, slip-stream effect, of course, not
being reckoned with.
The three-view drawing of the airplane indicates a setting
of + H0 of the upper wing (U.S. A. 15) and a setting of
-2° of the lower wing (U. S. A. 27) to the thrust line, the
landing angle of which is indicated as 12° . This gives us
in figure 2, a Ky of 0.00265 and a landing speecJ of 59 m. p. h.
The maximum Ky of 0.003, landing speed 55 m. p. h., occurs
of course at about 18°, since the Kym of U.S. A. 15 occurs
at 11°, and of U.S. A. 27 at 17° or at 161° and 19°, respectively,
of the thrust line. The present arrangement of the
wings and landing angle has no apparent reason as a basis
for justification. In the first place, positive decalage
introduces a loss in aerodynamic efficiency unless accompanied
by negative stagger.' Positive decalage flattens
· the burble point, which is not necessary, and lowers it,
which is not desirable. It also increases the static stability
of the wing cellule alone, but a tail has already been provided
to furnish static stability of the airplane.
A setting of the upper wing of 0° and of the lower wing of
+ 2° with a landing angle of 14° seems logical, as a maximum
K, of approximately 0.003 would be realized, with a
consequent reduction in landing speed of 4 m. p. h. This
arrangement gives us a small negative decalage (-1 °,
considering angles of zero lift) which should be and is
accompanied by a small positive stagger.
The indicated " fineness" is 100 for the present arrangement,
with a probable high speed of about 117 m. p. h .,
which is G.4 per cent below specifications for this type of
airplane. It. is felt that the reco=ended wing arrangement
will result in a small, but not inconsiderable, increase
in " fineness " and general performance. The low
1 "Systematic Calculations of Lift and Drag of Biplanes," Technische
Berichte, Vol. II, No. 2, by R . Fuchs.
"fineness" is due largely to the awkward shape of the
fuselage.
The projected arrangement may require a tail setting
other than +2°. A new wind-tunnel test may be run,
unless it is not desired to ne~lect slip-stream effect, in
which case reference should be made to Air Service Information
Circular, Vol. II, No. 102.2
TABLE !. - Forces and moments.
AUTHORITY: AERODYNAMICAL LAB., M. I. T., DEC. , 1920.
VELOCITY : 30 M. P. H. MODEL: 1/24 SCALE .
STABILIZER SET AT 0° TO THRUST LINE.
i Lift. Drag. Lift-drag. Mom. 0-i
0 0 '
- 4 -0.060 0.1069 -0.57 -0. 096 -56 19
- 2 + .096 .0880 1.09 - .160 44 32
0 . 348 . 0817 4. 26 - .210 13 12
+ 2 .601 . 0911 6.60 - .242 6 37
4 . 816 .1076 7. 58 - .258 3 31
6 1. 051 . 1330 7. 90 - . 275 l 13
1. 261 .1656 7.62 - .296 - 31
10 1. 461 . 2054 7.12 - .322 - 2
12 1.669 . 2523 6.62 - .355 -3 25
14 1. 854 . 2995 6.20 - . 389 - 4 50
16 1. 936 . 3491 5.54 - .464 - 5 46
18• 1. 948 . 4978" 3. 91 - .816 - . 3 39
20 1. 930 .6240 3.09 -1.150 - 2 4
24 1. 633 . 7455 2.19 -1. 533 + 32
28 1. 546 . 8405 1. 84 1.695 31
32 1. 485 .9850 1. 51 -1. 830 1 30
36 1. 430 1. 1018 1. 30 -2.040 1 34
40 1. 401 l. 2346 1.14 -2.255 15
STABILIZER SET AT + 2' TO THRUST LINE.
I -4 -0.030 0.1011 -0.30 -0. 251 -69 18
0 + .400 . 0817 4. 90 - .371 11 32
+ 4 . 868 .1132 7.67 - .436 3 26
8 1. 325 . 1725 7.68 - .491 - 35
12 1. 713 . 2578 6. 63 - .560 - 3 26
16 1. 935 . 3638 5. 32 - .673 - 5 22
20 1. 920 .6380 3.01 -1. 333 - 1 37
STABILIZER ·s E'l' AT -2° TO THRUST LINE.
I - 4 -0.121 0.1053 -1.15 +o. 083 -37 I 0 + .329 .0847 3. 89 - .024 +14 25
+ 4 . 803 .1112 7. 22 - .086 .3 53
8 1. 225 .1683 7.45 - .123 - 21
12 L 650 .2484 6. 63 - .180 - 3 2G
16 L 883 . 3459 5. 44 - .290 - 5 35
20 1. 861 .6125 3.04 - 1. 030 I - 1 38
Lift in pounds ou model. _Drag in pounds on model. Moment in
inch-pounds on model. 0° 111c1deuce referred to thrnst ltue.
2 " A Method for Determining the Angular Setting of a Tail Plane to
GiveBalan.ceat Any Given Condition.'' _
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Description

Title	Report on wind-tunnel test of armored pursuit airplane PG-1, type IV (Airplane Section, S. & A. Branch)
Author	United States. Army. Air Service. Engineering Division.
Date Issued	1921-05-01
Series Information	Air Service information circular (Aviation) ; v. 2, no. 166; McCook Field report ; Serial no. 1499
Description	A model of an armored single-seater pursuit airplane for ground work, designed by Engineering Division, was tested at M. I. T., December 1920. The usual tests for forces and moments with various settings of the tail plane were made. The data is given in the accompanying tables and figures.
Subject Terms	Wind tunnel testing; Aeronautics--Research; Aeronautics--Systems engineering; Airplanes--Design and construction; Airplanes--Models--Aerodynamics; Airplanes, Military
Report Publisher	Washington, D.C. : Chief of Air Service
File Name	asic166_ocr.pdf
Document Type	Text
File Format	PDF
File Size	6.47 Mb
Document Source	Auburn University Libraries. Government Documents.
Digital Publisher	Auburn University Libraries
Rights	This document is the property of the Auburn University Libraries and is intended for non-commercial use. Users of the document are asked to acknowledge the Auburn University Libraries.
Submitted By	Coates, Midge
OCR Transcript	N Auburn University Libraries 11111111~111111m~ \-. -------.3. .1::7.0.:6: .0.2::5. .8~4804~ o ~ ) M9COOK F'IELD REPORT SERIAL No. 1499 AIR SERVICE INF() MA TION CIRCULAR (AVIATION) PUBLISHED BY THE CHIEF OF AIR SERVICE, WASHINGTON, D. C. May 1, 1921 · No. 166 REPORT ON WIND-TUNNEL TEST OF ARMORED PURSUIT AIRPLANE PG-1, TYPE IV (AIRPLANE SECTiON, S. & A. BRANCH) V Ralph Brown Draughon LIBRARY MAR 28 2013 Non-Depoitory Auburn University Prepared by Engineering Division, Air Service McCook Field, January 31, 1921 • WASHINGTON GOVERNMENT PRINTING OFFICE 1921 REPORT ON WIND-TUNNEL TEST OF ARMORED PURSUIT AIRPLANE PG-1, TYPE IV .. A model of an armored single-seater pursuit airplane for ground work, designed by Engineering Division, was test~d at M. I. T. ,' December, 1920. The usual tests for forces and moments with various settings of the tail plane were made. The data is given in the accompanying tables and figures. Figure 1 gives an impressioi;i of the external appearance of the airplane. Figures 2, 3, and 4 give the various lift, L/D and drag curves, and figures 5, 6, and 7 are vector diagrams for tail settings of + 2°, 0°, and -2°, respectively . Settings of + 2° and 0° give unstable arrangements. whereas a setting of -2° gives a condition .of shbility which is satisfactory, slip-stream effect, of course, not being reckoned with. The three-view drawing of the airplane indicates a setting of + H0 of the upper wing (U.S. A. 15) and a setting of -2° of the lower wing (U. S. A. 27) to the thrust line, the landing angle of which is indicated as 12° . This gives us in figure 2, a Ky of 0.00265 and a landing speecJ of 59 m. p. h. The maximum Ky of 0.003, landing speed 55 m. p. h., occurs of course at about 18°, since the Kym of U.S. A. 15 occurs at 11°, and of U.S. A. 27 at 17° or at 161° and 19°, respectively, of the thrust line. The present arrangement of the wings and landing angle has no apparent reason as a basis for justification. In the first place, positive decalage introduces a loss in aerodynamic efficiency unless accompanied by negative stagger.' Positive decalage flattens · the burble point, which is not necessary, and lowers it, which is not desirable. It also increases the static stability of the wing cellule alone, but a tail has already been provided to furnish static stability of the airplane. A setting of the upper wing of 0° and of the lower wing of + 2° with a landing angle of 14° seems logical, as a maximum K, of approximately 0.003 would be realized, with a consequent reduction in landing speed of 4 m. p. h. This arrangement gives us a small negative decalage (-1 °, considering angles of zero lift) which should be and is accompanied by a small positive stagger. The indicated " fineness" is 100 for the present arrangement, with a probable high speed of about 117 m. p. h ., which is G.4 per cent below specifications for this type of airplane. It. is felt that the reco=ended wing arrangement will result in a small, but not inconsiderable, increase in " fineness " and general performance. The low 1 "Systematic Calculations of Lift and Drag of Biplanes," Technische Berichte, Vol. II, No. 2, by R . Fuchs. "fineness" is due largely to the awkward shape of the fuselage. The projected arrangement may require a tail setting other than +2°. A new wind-tunnel test may be run, unless it is not desired to ne~lect slip-stream effect, in which case reference should be made to Air Service Information Circular, Vol. II, No. 102.2 TABLE !. - Forces and moments. AUTHORITY: AERODYNAMICAL LAB., M. I. T., DEC. , 1920. VELOCITY : 30 M. P. H. MODEL: 1/24 SCALE . STABILIZER SET AT 0° TO THRUST LINE. i Lift. Drag. Lift-drag. Mom. 0-i 0 0 ' - 4 -0.060 0.1069 -0.57 -0. 096 -56 19 - 2 + .096 .0880 1.09 - .160 44 32 0 . 348 . 0817 4. 26 - .210 13 12 + 2 .601 . 0911 6.60 - .242 6 37 4 . 816 .1076 7. 58 - .258 3 31 6 1. 051 . 1330 7. 90 - . 275 l 13 1. 261 .1656 7.62 - .296 - 31 10 1. 461 . 2054 7.12 - .322 - 2 12 1.669 . 2523 6.62 - .355 -3 25 14 1. 854 . 2995 6.20 - . 389 - 4 50 16 1. 936 . 3491 5.54 - .464 - 5 46 18• 1. 948 . 4978" 3. 91 - .816 - . 3 39 20 1. 930 .6240 3.09 -1.150 - 2 4 24 1. 633 . 7455 2.19 -1. 533 + 32 28 1. 546 . 8405 1. 84 1.695 31 32 1. 485 .9850 1. 51 -1. 830 1 30 36 1. 430 1. 1018 1. 30 -2.040 1 34 40 1. 401 l. 2346 1.14 -2.255 15 STABILIZER SET AT + 2' TO THRUST LINE. I -4 -0.030 0.1011 -0.30 -0. 251 -69 18 0 + .400 . 0817 4. 90 - .371 11 32 + 4 . 868 .1132 7.67 - .436 3 26 8 1. 325 . 1725 7.68 - .491 - 35 12 1. 713 . 2578 6. 63 - .560 - 3 26 16 1. 935 . 3638 5. 32 - .673 - 5 22 20 1. 920 .6380 3.01 -1. 333 - 1 37 STABILIZER ·s E'l' AT -2° TO THRUST LINE. I - 4 -0.121 0.1053 -1.15 +o. 083 -37 I 0 + .329 .0847 3. 89 - .024 +14 25 + 4 . 803 .1112 7. 22 - .086 .3 53 8 1. 225 .1683 7.45 - .123 - 21 12 L 650 .2484 6. 63 - .180 - 3 2G 16 L 883 . 3459 5. 44 - .290 - 5 35 20 1. 861 .6125 3.04 - 1. 030 I - 1 38 Lift in pounds ou model. _Drag in pounds on model. Moment in inch-pounds on model. 0° 111c1deuce referred to thrnst ltue. 2 " A Method for Determining the Angular Setting of a Tail Plane to GiveBalan.ceat Any Given Condition.'' _ 40698- 21 (3) ' ~ ----'1./6"---- r--- ---- ---- --- -------- --------- - 1 \ I I \ t=.3.685"---- .76" FIG. 1. 3IN6L'.E .5E/1TEI? 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