TRACKING RATE MK I HAND CONTROL

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP89B00487R000300650002-0
• Release Decision: RIFPUB
• Original Classification: K
• Document Page Count: 9
• Document Creation Date: December 22, 2016
• Document Release Date: August 22, 2011
• Sequence Number: 2
• Publication Date: January 1, 1957
• Content Type: REPORT

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JANUARY 1957
Prepared for Contract SC 21-54
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DRIFT SIGHT TRACKING ACCURACY
INTRODUCTION
During the weeks of November 12th and November 26th, 1956 extensive
tests were conducted at the Ranch to determine the tracking rate accuracy of
the MK I Hand Control and Drift Sight (mechanical unit).
EQUIPMENT
Earlier tests both in the field and in the laboratory resulted in
the following reworking of Hand Control and Drift Sight parts:
(a) The flexible control cables were rerouted in the aircraft to
minimize sharp bends.
(b) Residual oil in the flexible cables made them stiff at low temper-
atures. New flexible cables, free of oil were installed and
used for the tests.
(c) Lubricating oils in the Drift Sight head scanning mechanism
were carefully selected and sparingly used to eliminate any
stiffness at low temperatures.
(d) Backlash in the gear train of the Hand Control was minimized by
inserting spring take-up on some gear meshes. Backlash was
minimized also by redesigning the boresight adaptors to eliminate
a bevel gear mesh.
(e) A new reticle was installed. which had a center break cross hair
at the optical center of the Drift Sight.
(f) Tolerances increased for differential in temperature coefficient
of expansion of metals.
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TEST METHOD
A test program entitled "Drift Sight Test Program All dated November 8,
1956 was used for coordinating the tests conducted. A copy of this program
is attached. In place of the Century recorder an accurate Wheatstone bridge
was furnished the pilot to measure the value of the IMC potentiometer setting
in the Hand Control. This measured setting was compared with computations
made from the negatives taken. Throughout these tests the vehicle's auto-
pilot was used.
ANALYSIS
The time base for measurements on the negatives was established by
examining the recorded clock sweep second hand and further by averaging the
time for a large number of frames. In these tests the camera intervalometer
proved stable and yielded a frame interval of 15.00 seconds.
There were a total of ten useful sets of information from the two
missions flown. Table I gives the tracking rate error (difference between com-
putations from film and setting of the Hand Control's. IMC potentiometer)
as the average error for the duration of the time interval.
Total Time
Interval
(Secs)
Rate Error
(Milrad/Sec)
150-164
210
-.04
226-233
105
f 1.5
259-265
90
-.7
133-139
90
/.1
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127 -134
-.75
175-186
L.125
202-208
-.395
252-260
-.63
302-306
-.506
345-353
-.381
The above data is plotted as a graph in figure 1.
The allowable error is ~ .3 milrad/sec to f .6 milrad/sec for
the C Configuration, depending upon the shutter speed.
In order to take advantage of the considerable number of tests run
the RLS errors for aircraft and for the Hand Control were computed. The values
were as follows:
RMS error in aircraft motion
RMS error of aircraft plus Hand
Control
Resultant RMS error of Hand Control
alone
f 1.37 mr/sec.
1.66 mr/sec.
.926 mr/sec.
Further analysis of the film data showed, in the case of the 210
second test run that the aircraft motion was:
75 foot altitude variation (porpoising) in 40 seconds.
This is equivalent to an image motion in the viewfinder of 15 mils
(angular) or 4 the recticle square. This is quite a small motion and would not
warrant stabilization.
An error of .3 mr/sec. is equivalent to motion of an object in the
viewfinder of k the reticle square in 144 seconds (ie 600 angular sweep at
nominal IMC rates).
Despite these values the test runs show that the pilot permitted
the object to move lk reticle squares without making corrections. The con-
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clusion then is: more pilot training is :required to yield the accuracy
inherent in the system and required by the C Configuration.
A tabulation of each of the test points, as derived from measurements
on the various film frames is included in Appendix I. The second column of
this tabulation is the actual IMC rate of the aircraft over the fifteen second
interval. A plot of these values for frames 150 to 164 appears in figure 2.
ERRORS IN TEST METHOD
The values given in Table I are overall system errors and include:
(a) Test instrumentation error.
(h) Pilot error in setting tracking rate.
(c) Vehicle motion in pitch, roll and yaw.
The test instrumentation error rests primarily in the accuracy of
the Wheatstone bridge used in measuring the INC potentiometer. The bridge is
accurate to j .1% which is equivalent to an error in IMC of f .012 mr/secs.
The error in computation of IMC rate from film data is
nominal IMC rate (which was 9 to 10 mr/sec:).
Pilot error in setting the tracking rate is a human error which is
difficult to evaluate and one which will always be present in the system.
Training and experience can minimize it but not eliminate it.
CONCLUSION
The Hand Control and Drift Sight are capable of yielding tracking rate
settings which are within the ~ .3 mr/sec error allowable in the system composed
of Drift Sight, aircraft, pilot and C Configuration. Proper cable routing,
degreased cables and scanning head and adequate pilot training will permit this
accuracy to be maintained.
TWM:hm 1-14-57
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FIG 1
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FRAME
NOS.
DEVIATION FROM AVG.
SEC
MR/SEC
RATE FROM NEG.
150-151
.37
9.64
151-152
,' .39
10.4
152-153
- .644
9.366
153-154
- .551
9.459
154-155
,'2.29
12.30
155-156
-2.23
7.78
156-157
.78
10.79
157 -158
.136
10.146
158-159
.993
9.017
159 -160
-1.14
11.15
160-161
.61
10.62
161-162
.26
10.27
162-163
- .26
9.75
163-164
.551
9.459
226-227
- .1
11.2
227-228
- .6
10.7
228-229
,'1.6
12.9
229-230
,'1.4
12.7
230-231
-3.0
8.3
231-232
-2.0
9.3
232-233
,'2.6
13.9
259-260
,'1.552
10.681
260-261
- .731
8.398
261-262
,' .666
9.795
262-268
,' .844
9.973
263-264
,' .168
8.961
264-265
-2.163
6.966
133-134
,' .68
10.5
134-135
-1.12
8.7
135-136
- .48
10.3
136-137
,'1.38
11.2
137-138
- .27
9.58
138-139
- .12
9.70
127-128
- .019
9.693
128-129
.291
10.003
129-130
.201
9.913
130-131
1.768
11.48
131-132
- .559
9.153
132-133
- .832
8.88
133-134
- .846
8.866
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FRAME
NOS.
DEVIATION FROM AV.
MR/SEC
MR/SEC
RATE FROM NEG.
175-176
.702
9.833
176-177
.495
11.03
177-178
- .005
10.53
178-179
- .935
9.60
179-180
.018
10.553
180-181
1.638
12.173
181-182
.345
10.88
182-183
.111
10.646
183-184
-3.109
7.426
184-185
.325
10.86
185-186
1.818
12.353
202-203
.436
11.278
203 -204
-1.582
8.260
204-205
.104
9.946
205-206
2.867
12.709
206-207
.157
9.999
207 -208
-2.986
6.859
252-253
-1.611
7.823
253-254
-2.517
6.917
254-255
.183
10.617
255-256
-1.685
7.749
256-257
1.169
10.603
257-258
- .339
9.095
258-259
.355
9.789
259-260
3.446
12.880
302-303
- .429
9.164
303-304
2.228
11.821
304-305
.739
10.332
305-306
-2.539
7.054
345-346
- .498
9.863
346-347
,'1.283
11.644
347-348
.142
10.503
348-349
-1.592
8.769
349! 350.
1.160
11.521
350-351
1.454
11.815
351-352
-1.332
9.029
352-353
- .613
9.748
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