THE AERODYNAMICS OF A SPINNING SHELL. 
381 
Table VI. —Values of the Stability Coefficient and the Air Couple deduced from 
Analysis of the Stable Shells. 
Summary of Notation used in the Headings of this Table. 
/ul sin S — couple due to air forces. 
s = = stability coefficient. 
4 p 
v = mean velocity of shell, f.s. 
p = air density, lb./(ft.) 3 . 
a — velocity of sound, f.s. 
f u (v/a) — p./(pv 2 r 3 ), the air couple coefficient. 
N.B.—The values of s, p and / M have not been corrected in this table for the effect of the cards. 
1 . 
2. 3. 
4. 
5. 
6. 
7. 
8. 
Round No. 
or group of 
rounds. 
Twist 
of 
rifling. 
Value of s 
deduced from 
observation. 
Mean value 
of V 
corresponding 
to value 
of s. 
Value of p. 
Value of 
/m (v/a). 
Value of 
v/a. 
Total 
percentage 
spread of 
s or p in 
group. 
I. 11, 12 
1/40 
1-113 
905 
1220 
9-58 
0-824 
I. 14 
1/40 
1-087 
906 
1250 
9-71 
0-825 
4-1 
I. 13 
1/40 
1-131 
919 
1230 
9-26 
0-837 
I. 22-24 
1/30 
1-61 
1090 
2230 
11-85 
0-996 
3-2 
I. 25,26 
1/30 
1-66 
1283 
3030 
11-62 
1-173 
1-7 
I. 27, 28 
1/30 
1-74 
1515 
4000 
11-09 
1-388 
1-1 
I. 5- 7 
1/40 
1-005 
1535 
3920 
10-89 
1-394 
0-9 
I. 15, 16 
1/40 
1-137 
2084 
6410 
9-36 
1-897 
I. 1 
1/40 
1-180 
2104 
6390 
9-40 
1-916 
6-7 
I. 2- 4 
1/40 
1-118 
2117 
6750 
9-80 
1-927 
I. 19 
1/40 
1 • 152 
2217 
7190 
9-22 
2-023 
I. 20, 21 
1/40 
1 • 133 
2285 
7800 
9-41 
2-085 
1-9 
II. 8-10 
1/40 
1-172 
922 
1170 
8-71 
0-840 
4-9 
II. 17-19 
1/30 
1-69 
1091 
2000 
10-46 
0-997 
0-8 
II. 24 
1/30 
1-72 
1259 
2700 
10-86 
1-153 
II. 5- 7 
1/40 
1-121 
1553 
3680 
9-98 
1-408 
4-7 
II. 22, 23 
1/30 
1-94 
1546 
3800 
9-95 
1-416 
3-8 
1 
