PROPOSAL FOR A PAYLOAD INERTIA BALANCE SUBSYSTEM (PIBS) FOR THE CORONA J-3 SYSTEM

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP79B00752A000300060001-9
• Release Decision: RIPPUB
• Original Classification: T
• Document Page Count: 19
• Document Creation Date: December 23, 2016
• Document Release Date: June 24, 2013
• Sequence Number: 1
• Publication Date: November 7, 1966
• Content Type: REPORT

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/
C / SPECIAL HANDLINg.,
NO. A/P 66-01097
PROPOSAL FOR A PAYLOAD
INERTIA BALANCE SUBSYSTEM (PIBS) FOR
THE CORONA J-3 SYSTEM
NOVEMBER 7, 1966
The data furnished in this Proposal shall not be disclosed
outside the Government or be duplicated, used or disclosed in
whole or in part for any purpose other than to evaluate the proposal;
provided, that if a contract is awarded to this offeror as a result
of or in connection with the submission of such data, the Government
shall have the right to duplicate, use, or disclose this data to the
extent provided in the contract. This restriction does not limit the
Government's right to use information contained in such data if it
is obtained from another source.
Tor SECRET
C/SPECIAL HANDLING
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TABLE OF CONTENTS
1.0 INTRODUCTION
1.1 Purpose
1.2 Requirements
1. 3 Methods of Satisfying Requirements
2.0 TECHNICAL DESCRIPTION
3.0 ENVIRONMENTAL SURVIVAL CAPABILITY
3. 1 Qualification Testing
4.0 COST ELEMENTS
5.0 COST EFFECTIVENESS
Page
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1 . 0 INTRODUCTION
1. 1 Purpose
This proposal describes a Payload Inertia Balance Subsystem
hereafter called FIBS. Its basic purpose is to provide momentum balance
for the J-3 payload during periods of camera start-up and shut-down so
that the J-3 Panoramic cameras may be started and shut down indepen-
dently of each other. This capability permits delaying start of the aft
looking camera for the time interval represented by 6 frames when the
J-3 payload is operated in normal stereoscopic mode. It also permits
shut-down of the forward looking camera at the time of departure from
a target area and shut-down of the aft looking camera later at the time
interval represented by 6 frames of camera operation. Incorporation
of FIBS into the J-3 Payload will result in the following advantages:
a) Five frames of film (1 frame allowed for start-up and
shut-down) are saved for each photographic operation on
each camera by avoiding running cameras before and
beyond the target area to obtain stereoscopic coverage.
For a total mission, the total film saved is 15 percent.
b) While the same advantage might be gained by allowing
the Agena attitude control system to correct the roll
rates induced by delayed camera starts and shut-down,
FIBS is more efficient as its weight is less than the
control gas that would be expended. Calculations show
1
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that 90 pounds of vehicle gas and_b_p_ttle weight would be
required. PIBS weight is estimateLto jlt 24 pounds.
c) It removes a theoretical degrading image motion from the
photography. Due to the nature of smear, the result
of removal of this smear may not be physically detectable
by the photographic interpreter. However, its effect on
precision measurement accuracies may be of noticeable
significance.
1.2 Requirements
In its present configuration, i. e., without FIBS, it is planned
to begin each photographic operation of the J-3 system by simultaneously
starting both panoramic cameras. Each operation is terminated by
simultaneously stopping both cameras. It is readily seen that this mode
of operation is inefficient as it uses excess film to obtain stereoscopic
coverage of a given area. This arises because of the rigid mounting of
the two cameras to maintain a fixed angle of convergence. It is also
apparent that this mode of .operation results in obtaining six( frames of
non-stereoscopic coverage with the aft-looking camera at the start of
an operation and six frames with the forward looking camera at the end
of an operation. This non-stereoscopic coverage has limited usefulness
for either intelligence or cartographic operations.
For forecast typical missions with the currently used 3.2 mil
2
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thick film, the number of starts and stops should be approximately 180.
Assuming 1 frame is of marginal value due to camera acceleration and
braking characteristics, simultaneous starting and stopping is wasting
five frames of photography in non-stereoscopic coverage. This means
that 900 more stereoscopic pairs could be obtained which is a 15 per-
cent gain per mission. In the case of ultra-thin base film and the
recent trends in shortening camera operational bursts, the number of
camera starts could be considerably higher. If the design limit of
400 starts stated in the J-3 Pressure Make-up Unit Requirements is
used as the upper limit, the resulting saving of film is equivalent to
2000 stereoscopic pairs.
The intrinsic value of this saved film is easily recognizable.
It may be devoted to additional intelligence coverage for search or it
may be allocated to the cartographic users thereby enabling them to
accumulate coverage at a higher rate. The saved film for an 180 start
mission represents three times the film presently allocated to the carto-
graphic community.
1.3 Methods of Satisfying Requirements
It is possible to permit delayed starts of the J-3 instruments in
the present system. As a result of the momentum unbalance, roll rates
as high as 150 degrees per hour are induced. As this exceeds the roll
threshold of the Agena attitude control system by a factor of 2.5, the
3
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roll jets are activated and remain activated until the roll rate and roll
attitude again lie within the control deadbands of the system. Calcu-
lations shows that for each delayed start and stop operation, 1/4 pound
of control gas will be expended. Over the duration of an average fore-
cast J-3 mission on 3.2 mil thick film, there are 180 operations.
Therefore, 45 pounds of gas would be required. Current design practice
shows that for each pound of gas, one pound must be added for bottle
structural weight. Hence, the potential weight requirement is 90
pounds. With ultra thin base film where the maximum number of
starts may be as high as 400, 100 pounds of gas would be required and
200 pounds required for gas and bottle. This is sufficiently inefficient
in either case to justify seeking other means to overcome the momentum
imbalance of delayed starts.
Analysis of the amount of momentum imbalance is shown on
Figure 1. Four possible methods of overcoming this unbalance were
considered. Each of these methods is briefly discussed below:
1. Increase the roll inertia by weights on extendable booms.
Increasing the roll inertia will reduce the roll rates if
the boom can be made stiff enough (which would be diffi-
cult for the small angle the vehicle rolls through). However,
the roll momentum would be unchanged - still equal to the
unbalance momentum of the instrument. Since the amount
of control gas required is basically a function of the momen-
tum unbalance, increasing the roll inertia would provide
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Iw (FT. -LB. -SEC)
MOMENTUM UNBALANCE
MONO OPERATION
Inst. Only
Inst. +
S. Spool
Proposed Iw Flywheel
Counter Balance
Ab.
0
0 a
Cl)
Eri
ui
Figure 1
S. Spool
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4'
very little help in reducing control gas consumption.
2. Put roll control gas jets out on a boom. These jets need
not be the Agena control gas jets, but could be additional
jets that start to discharge when the instrument starts
and shut off when the instrument is at speed. The boom
simply gives the jets a better lever arm and the resulting
gas savings will be the ratio of the boom length to the
present Agena control gas jet radius. In addition to a
reduction in the amount of control gas used, the vehicle
roll rates mould be reduced. In this case, deflection of
the boom is less detrimental since the jet will move
in space instead of keeping the mass fixed in space and
letting the vehicle roll to produce the required deflection
in the boom. (There will be a time lag while the boom
tip moves to the deflected position.)
3. Combine methods 1 and 2. No advantages of adding mass
to the jets on the end of the boom can be thought of. It
would either increase the lag time for the jets to load the
cantilever beam or require a very stiff boom.. The
added mass would not reduce the amount of control gas
required appreciably, and it would increase the weight of the
system.
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4. Install a momentum wheel. This could be an open loop
system installed mechanically and electrically independent
of the instruments. The fly wheel would start when the
first instrument starts, accelerate approximately with
the instrument and come to speed when the instrument
comes to speed. It would decelerate when the second
instrument starts and come to a stop when the second
instrument is at speed. The fly wheel would reverse
this procedure on instrument shutdown. This scheme
requires but one motor and one fly wheel. No power
will be required when both instruments are at speed
or when both instruments are off. If it is desirable to
have a pick-off to tell instrument speed and acceleration,
this could be done with a decoder or tachometer from an
idler roller between the supply and the instrument. The
overall result would be both a reduction in gas consumption
and a reduced roll rate.
It is noted that none of the four systems provides perfect momentum
balance. Choice of system is dictated by system complexity, weight and
degree of compensation achieved. A brief comparison of these characteristics
shows that the inertia or momentum wheel is inherently more efficient
than the other three approaches in terms of weight and system complexity.
7
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66 rt
It is also possible to achieve a high degree of inertia balance during
critical periods of starting and stopping the cameras with minimum time
lags. For these reasons, the momentum wheel design is selected.
2.0 TECHNICAL DESCRIPTION
The PIBS Subsystem consists of a momentum wheel driven by a
reversible DC motor and controlled by a tachometer sensing J-3 camera
speed. The momentum wheel is constructed so as to concentrate its
mass at its circumference. This gives it a high moment of inertia. The
principle of the bicycle wheel employing wire spokes to give the wheel
rigidity will probably be followed in construction of the wheel.
The wheel will be driven by a small electric motor similar in
type to that used to drive the J-1 camera system.
A tachometer sensing camera, speed will control the voltage to the
motor and hence its speed, allowing synchronization of the camera and
momentum wheel to maximize the inertia balance of the system. The
power consumption of the motor and tachometer assembly has been estimated
at 3.0 watt-hours per operate period. For the 180 start mission, 540
watt-hours are required. For the 400 starts for missions employing
ultra thin base film 1200 watt-hours are required. This is within the
power margins for the J-3 mission without additional batteries.
The weight of the momentum balance system is:
Motor
Gearing
2.5 lbs.
1.0 lb.
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Flywheel
Tach and Support
Support Structure
Electrical boxes and wires
Total System Weight
10.0 lbs.
, 5 lbs.
5.0 lbs.
5.0 lbs.
24. 0 lbs.
Installation of the FIBS is shown in Figure 2. Operating principles
of the PIBS are illustrated by Figure 3, Operating time is shown in
Figure 4.
A proposed electrical design for FIBS is shown in Figure 5. This
design will use flight proven components to maximize reliability.
Command functions will be accomplished through relays. No new com-
mand requirements are imposed by FIBS.
3.0 ENVIRONMENTAL SURVIVAL CAPABILITY
The equipment shall be proven capable of surviving launch and
operating use environments. This shall be demonstrated by qualification
testing of a production model and unit acceptance and flight sys terns testing
of the flight units.
3. 1 Qualification Testing
Qualification testing shall be accomplished to the stress levels
specified in subsequent paragraphs.
3. 1. 1 Sinusoidal Vibration
1/2 inch peak to peak from 5 to 15 cps
9
.r
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PIBS INSTALLATION IN VEHICLE
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TAC #1 (El)
TAC #2 (E1,)
Start volt
Bias
Diff
Amp
Start volt
I Bias
n-
erte
if
mp
Di
Amp
Pw
Amp
Motor
Gear
Box
Tv'
a)
?
1
Tacho-
meter
CW
Rotation
PAYLOAD INERTIA BALANCE BLOCK DIAGRAM
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Figure 3
Brake
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V
FLYWHEEL ROTATION VS. TIME
V)
4
4?) PCS
Z W
ou) 4 O.
e p.
ti 4_,
Ul 4-)
CV r-t C/)
TIME (SECONDS)
Figure
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,stst. #2
OP.
, A to B
Transfer
Inst. #2
TAC
24V
Energize to
release brake
A to B
Transfer
Relay
Reset
PAYLOAD INERTIA BALANCE SYSTEM SCHEMATIC
Figure 5
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7 g's from 15 to 20 cps (0 to peak)
5 g's from 20 to 400 cps (0 to peak)
7.5 g's from 400 to 2000 cps (0 to peak)
3.1.2 Random Vibration
All three axes
0.05 g2 /cps from 20 to 400 cps
0.12 g2 /cps from 400 to 2000 cps attaining 14.5 g's
r ms overall acceleration
3.1.3 Acceleration
11.0 g's in the longitudinal axis in the plus direction.
2.0 g's along the lateral axes in both direction (plus and minus)
3.1.4 Shock
20 g's in the longitudinal axes with a pulse duration of
6 milliseconds. Equipment must survive 3 such shocks.
5 g's in the lateral axes with a pulse duration of 6 milli-
seconds. Equipment must survive 3 such shocks.
3.1.5 Thermal Altitude Test
The FIBS shall be placed in a test chamber and pressure reduced
to 10-5 mm Hg or lower. While maintaining the reduced pressure, the
temperature shall be cycled as follows:
Cycle
1
Temperature Time
750F 8 hours
105oF 8 hours
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Cycle
3
4
5
Temperature Time
110oF
35oF
20oF
8 hours
8 hours
8 hours.
At the end of each cycle the equipment shall be operated through
a maximum duty cycle simulating a camera start-up and a camera
shut-down.
After the operation for cycle 5 is completed, the pressure and
temperature shall be returned to ambient laboratory levels and the
equipment shall be operated through a normal functional test.
3.1.6 Calendar and Operating Life. The PIBS shall be designed to
have a chlendar life in excess of one year. The useful operating life
design goal of the FIBS shall be 650 hours which is equivalent to 99 per-
cent reliability at the 50 percent confidence level.
3. L7 Electromagnetic Compatibility
The FIBS system shall fulfill the requirement that its electrical
and electronic equipment shall op er ate successfully, not only independently,
but also in conjunction with other equipment which may be placed nearby.
This requires that the operation of all such equipment shall not be -
adversely affected by interference voltages and fields eachiqg _from ,
external sources. It also requires that such equipment shall not in itself
be a source of interference which might adversely affect the operation of
?
other equipments. Sufficient EMI testing shall be accomplished to verify
that these requirements are met.
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4. 0 COST ELEMENTS
The cost of the PIBS System is estimated as follows:
a) Non-recurring costs for development, tooling, and AGE
modifications
Unit cost for manufacturing, system integration, systems
testing, and other launch preparations
c) Total price for 15 flights consisting of CR-3 through CR-16
and QR-2
5.0 COST EFFECTIVENESS
As will be noted from Paragraph 1. 2 above it is estimated that
with the use of FIBS, 900 more stereoscopic pairs could be obtained per
mission which is a 15% gain. Therefore 15 flights (CR-3 - 16 incl. plus
QR-2) with FIBS would generate stereoscopic pairs which would be the
equivalent number obtained from 17. 647 missions without FIBS (15 4- .85).
The gain in coverage with use of FIBS would therefore be the equivalent
to the yield from 2. 647 missions resulting in a cost savings to the Govern-
ment in the approximate net amount of
50X1
50X1
50X1
omputed as 50X1
follows: MILLIONS
2. 64' flights at an estimated cost of
per flight
Less - Estimated cost of 15 FIBS
units
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5g66
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?
SEPT
OCT
NOV
Go Ahead
Preliminary DEsign
Breadboard Fab And Test
Detail Design
Long Lead Procurement
Qua/ Article Fab And Assy
Qua/ Testing
First Flight Article
Acceptance Testing
Retrofiting in CR? 3
i
I
CR-3 ( Ref.)
I
storaged
A
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