14. Snap/Lurch 6 Linear—add four time intervals
The model and its justification
Adding the four time intervals to the model represents a
significant complication to it. It represents the fact that we know only what
happened from one frame to the next, not anything within a frame. But the
details within a frame can strongly change the answer, and we must take account
of their effect on the answer and on its uncertainties.
This procedure calculates the speed of the rearward lurch of
JFK's upper body from the bullet, the body, the cloud, and the large fragments,
and incorporates 3-D motions of the cloud, the large fragments, and the body: Before doing that, however, it
interposes three steps having to do with the times. (1) It first calculates vsnap
and uses it to calculate tsnap. (2) Then it calculates ttransit
and combines it with tsnap with tdelay
to calculate tlurch. (3) Then it uses tlurch
and dfrags to calculate vfrags.
At this point it returns to the former procedure and (4) solves for vbodyafter
and vcloud. To simplify matters a bit, it sets vfrags23
= vfrag1 and fkefrags23 = fkefrag1.
Including these time intervals leaves the default solution
about the same: -1.04 and 401 ft s-1 for lurch and cloud,
respectively, versus -1.02 and 378 ft s-1 in Lurch 5 Linear. The
sensitivities and effects change, however, presumably to better reflect the true
situation.
(1) Equations for tsnap
(2) Equations for tlurch
(3) Equations for vfrags
(4) Simultaneous equations for vbodyafter and vcloud

fkefrags23 = fkefrag1

Default values of variables
| mbullet = 161 gr | vbullet = 1800 ft s-1 | mfrag1 = 0.027 gr |
| mbody = 85 lb | vbulletafter = 200 ft s-1 | mfrags23 = 0.01 gr |
| mcloud = 0.3 lb | Qfrag1 = 40° | fkefrag1 = 1.25 |
| mhead = 7 lb | Qfrags23 = 70° | fkefrags23 = fkefrag1 |
| Q = 12° | Qcl = 70° | fkebody = 1.2 |
| PE = 300 ft-lb | tdelay = 0.002 s | fxcl = 0.59 (calc.) |
| dtransit = 4 in | dsnap = 2.2 in | dfrag1 = 6 ft |
vbodyafter
= -1.04 ft s-1 vcloud
= 401 ft s-1
vfrag1
= vfrags23 = 363 ft s-1
vsnap = 5.1 ft s-1
ttransit = 0.33 ms
tsnap = 35.8 ms
tlurch = 16.5 ms
| Momentum | Energy | ||
| Before | After | Before | After |
| Pbullet = 1.26 | Pbulletafter = 0.14 | KEbullet = 1164 | KEbulletafter = 14 |
| Pbodyafter = -1.38 | KEbodyafter = 0.4 | ||
| Pcloud = 2.22 | KEcloud = 754 | ||
| Pfrag1 = 0.24 | KEfrag1 = 70 | ||
| Pfrags23 = 0.04 | KEfrags23 = 26 | ||
| PE = 300 | |||
Sensitivity analysis
Sensitivity analysis, Snap/Lurch 6 Linear
(Standard conditions in boldface)
|
mbullet |
vlurch |
mbody |
vlurch |
mcloud |
vlurch |
mhead |
vlurch |
vbullet |
vlurch |
|
|
|
|
|
|
|
4.0 |
-1.017 |
|
|
|
156 |
-1.025 |
|
|
|
|
4.5 |
-1.021 |
1750 |
-0.993 |
|
157 |
-1.029 |
65 |
-1.362 |
|
|
5.0 |
-1.026 |
1760 |
-1.003 |
|
158 |
-1.032 |
70 |
-1.265 |
|
|
5.5 |
-1.031 |
1770 |
-1.012 |
|
159 |
-1.035 |
75 |
-1.180 |
0.1 |
-0.329 |
6.0 |
-1.035 |
1780 |
-1.022 |
|
160 |
-1.038 |
80 |
-1.106 |
0.2 |
-0.731 |
6.5 |
-1.039 |
1790 |
-1.031 |
|
161 |
-1.041 |
85 |
-1.041 |
0.3 |
-1.041 |
7.0 |
-1.041 |
1800 |
-1.041 |
|
162 |
-1.043 |
90 |
-0.983 |
0.4 |
-1.302 |
7.5 |
-1.035 |
1810 |
-1.050 |
|
163 |
-1.046 |
95 |
-0.931 |
0.5 |
-1.533 |
8.0 |
-1.012 |
1820 |
-1.059 |
|
164 |
-1.048 |
100 |
-0.884 |
0.6 |
-1.742 |
8.5 |
-0.931 |
1830 |
-1.068 |
|
165 |
-1.051 |
105 |
-0.842 |
0.7 |
-1.935 |
9.0 |
-0.548 |
1840 |
-1.076 |
|
166 |
-1.053 |
|
|
0.8 |
-2.115 |
9.5 |
— |
1850 |
-1.085 |
|
|
|
|
|
|
|
10.0 |
— |
|
|
|
Sensitivity = |
Sensitivity = |
Sensitivity = |
Sensitivity = |
Sensitivity = |
|||||
|
Range = 0.03 |
Range = 0.52 |
Range = 1.79 |
Range = 0.47 |
Range = 0.09 |
|||||
|
vbulletafter |
vlurch |
PE |
vlurch |
Q |
vlurch |
Qcl |
vlurch |
mfrag1 |
vlurch |
|
|
|
0 |
-1.347 |
|
|
|
|
|
|
|
|
|
50 |
-1.299 |
7 |
-1.027 |
20 |
-2.086 |
0.022 |
-1.022 |
|
0 |
-0.944 |
100 |
-1.250 |
8 |
-1.029 |
30 |
-1.949 |
0.023 |
-1.026 |
|
50 |
-0.972 |
150 |
-1.200 |
9 |
-1.031 |
40 |
-1.767 |
0.024 |
-1.029 |
|
100 |
-0.997 |
200 |
-1.149 |
10 |
-1.034 |
50 |
-1.549 |
0.025 |
-1.033 |
|
150 |
-1.020 |
250 |
-1.095 |
11 |
-1.037 |
60 |
-1.303 |
0.026 |
-1.037 |
|
200 |
-1.041 |
300 |
-1.041 |
12 |
-1.041 |
70 |
-1.041 |
0.027 |
-1.041 |
|
250 |
-1.057 |
350 |
-0.984 |
13 |
-1.044 |
80 |
-0.773 |
0.028 |
-1.044 |
|
300 |
-1.070 |
400 |
-0.925 |
14 |
-1.048 |
90 |
-0.511 |
0.029 |
-1.048 |
|
350 |
-1.074 |
450 |
-0.864 |
15 |
-1.052 |
100 |
-0.264 |
0.030 |
-1.052 |
|
400 |
-1.066 |
500 |
-0.801 |
16 |
-1.057 |
110 |
-0.040 |
0.031 |
-1.055 |
|
|
|
550 |
-0.734 |
17 |
-1.061 |
120 |
+0.155 |
0.032 |
-1.059 |
|
|
|
600 |
-0.664 |
|
|
|
|
|
|
|
Sensitivity = |
Sensitivity = |
Sensitivity = |
Sensitivity = |
Sensitivity = |
|||||
|
Range = 0.12 |
Range = 0.68 |
Range = 0.03 |
Range = 2.24 |
Range = 0.04 |
|||||
|
mfrags23 |
vlurch |
Qfrag1 |
vlurch |
Qfrags23 |
vlurch |
fkefrags |
vlurch |
fkebody |
vlurch |
|
0.005 |
-1.040 |
|
|
|
|
1.00 |
-1.062 |
|
|
|
0.006 |
-1.040 |
20 |
-1.081 |
50 |
-1.066 |
1.05 |
-1.058 |
1.00 |
-1.041 |
|
0.007 |
-1.040 |
25 |
-1.073 |
55 |
-1.060 |
1.10 |
-1.053 |
1.05 |
-1.041 |
|
0.008 |
-1.040 |
30 |
-1.064 |
60 |
-1.054 |
1.15 |
-1.049 |
1.10 |
-1.041 |
|
0.009 |
-1.041 |
35 |
-1.053 |
65 |
-1.048 |
1.20 |
-1.045 |
1.15 |
-1.041 |
|
0.010 |
-1.041 |
40 |
-1.041 |
70 |
-1.041 |
1.25 |
-1.041 |
1.20 |
-1.041 |
|
0.011 |
-1.041 |
45 |
-1.027 |
75 |
-1.033 |
1.30 |
-1.036 |
1.25 |
-1.041 |
|
0.012 |
-1.041 |
50 |
-1.012 |
80 |
-1.026 |
1.35 |
-1.032 |
1.30 |
-1.041 |
|
0.013 |
-1.041 |
55 |
-0.996 |
85 |
-1.019 |
1.40 |
-1.028 |
1.35 |
-1.041 |
|
0.015 |
-1.041 |
60 |
-0.979 |
90 |
-1.011 |
1.45 |
-1.024 |
1.40 |
-1.041 |
|
0.015 |
-1.041 |
|
|
|
|
1.50 |
-1.019 |
|
|
|
Sensitivity = |
Sensitivity = |
Sensitivity
= |
Sensitivity = |
Sensitivity = |
|||||
|
Range = 0.00 |
Range = 0.10 |
Range = 0.06 |
Range = 0.04 |
Range = 0.00 |
|||||
|
dtransit |
vlurch |
dsnap |
vlurch |
dfrag1 |
vlurch |
tdelay |
vlurch |
|
0 |
-1.041 |
|
|
2 |
-0.995 |
|
|
|
1 |
-1.041 |
1.6 |
-1.027 |
3 |
-1.015 |
|
|
|
2 |
-1.041 |
1.8 |
-1.033 |
4 |
-1.030 |
0.000 |
-1.040 |
|
3 |
-1.041 |
2.0 |
-1.038 |
5 |
-1.038 |
0.001 |
-1.041 |
|
4 |
-1.041 |
2.2 |
-1.041 |
6 |
-1.041 |
0.002 |
-1.041 |
|
5 |
-1.041 |
2.4 |
-1.032 |
7 |
-1.036 |
0.003 |
-1.040 |
|
6 |
-1.041 |
2.6 |
-0.981 |
8 |
-1.025 |
0.004 |
-1.037 |
|
7 |
-1.040 |
2.8 |
-0.684 |
9 |
-1.005 |
0.005 |
-1.033 |
|
8 |
-1.040 |
|
|
10 |
-0.977 |
0.006 |
-1.026 |
|
|
|