1996 RTI (Research Triangle Institute) report "Modeling Unlikely Space-Booster Failures in Risk Calculations" (contract F04703-91-C-0112, RTI/5180/77-43F), prepared for the Department of the Air Force — limited-distribution analysis bundled into Release 01.
Distribution authorized only to USG agencies and contractors per the cover page. May exist in DTIC under limited distribution. Could not confirm a prior public release in this pass.
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RESEARCH TRIANGLE INSTITUTE /RTI
Contract No ■- FO4703-91-C-0112
RTI Report No. RTl/5180/77-43F
September 10, 1996
Modeling Unlikely Space-Booster
Failures in Risk Calculations
Final Report
Prepared for
Department of the Air Force
45th Space Wing (AFSPC)
Safety Office - 45 SW/SE
Patrick AFB, FL 32925
and
Department of theAir Force
30th SpaceWing (AFSPC)
19961025 122 Safety Office- 30 SW/SE
Vandenberg AFB, CA 93437
Distribution authorized to US Government agencies and their contractors to protect administrative/
operational use data, 10 September 96. Other requests for this document shall be referred to the 30th Space
Wing (AFSPC) Safety Office (30 SW/SE), Vandenberg AFB, CA 93437, or 45th Space Wing (AFSPC)
Safety Office (45 SW/SE), Patrick AFB, FL 32925.
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Contract No. FO4703-91-C-0112 RTI Report No. RTI/5180/77-43F
Task No. 10/95-77, Subtask 2.0 September 10, 1996
Modeling Unlikely Space-Booster
Failures in Risk Calculations
Final Report
Prepared by
James A. Ward, Jr.
Robert M. Montgomery
of
Research Triangle Institute
Center for Aerospace Technology
Launch Systems Safety Department
Prepared for
Department of the Air Force
45th Space Wing (AFSPC)
Safety Office - 45 SW/SE
Patrick AFB, FL 32925
and
Department of the Air Force
30th Space Wing (AFSPC)
Safety Office - 30 SW /SE
Vandenberg AFB, CA 93437
Distribution authorized to US Government agencies and their contractors to protect administrative/
operational use data, 10 September 96. Other requests for this document shall be referred to the 30th Space
Wing (AFSPC) Safety Office (30 SW/SE), Vandenberg AFB, CA 93437, or 45th Space Wing (AFSPC)
Safety Office (45 SW/SE), Patrick AFB, FL 32925.
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. eptember 10, 1996 1 Final
4. TITLE AND SUBTITLE 5. FUNDING NUMBERS
f.1odeling Unlikely Space-Booster Failures in Risk Galculations C: F04703-91-C-o112
TA:10/95-TT
6. AUTHORW •
James A. ard, Jr.
Robert M. Montgomery
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION
REPORT NUMBER
Research Triangle Institute * ACTA, Inc. **
113000 N. Atlantic Avenue · Skypark3 RTl/5180m-43F
Cocoa Beach, FL 32931 23430 Hawthorne Blvd., Suite 300
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9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/ MONITORING
AGENCY REPORT NUMBER
Department of the Air Force (AFSPC) Department of the Air Force (AFSPC)
30th Space Wing 45th Space Wing r\~'1~.1
- - -m.-t1<a-a
Vandenberg AFB, CA 93437 Patrick AFB, FL 32925
-Mr. Martin Kinna (30 SW/SEY) Louis J. Ullian, Jr. (45 SW/SED)
11. SUPPLEMENTARY NOTES
* Subcontractor
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Distribution authorized to US Government agencies and their contractors to protect
administrative/operational use data; 10 September 96. Other requests for this document shall
be referred to the 30th Space Wing (AFSPC) Safety Office (30 SW/SE),Vandenberg AFB, CA
93437, or 45th Space Wing (AFSPC) Safety Office (45 SW/SE), Patrick AFB, FL 32925. (!__,
13. ABSTRACT (Maximum 200 words)
Missile and space-vehicle performance histories contain many examples of failures that cause, or have the
potential to cause, significant vehicle deviations from the intended flight line. In RTl's risk-analysis program,
DAMP, such failures are referred to as Mode-5 failure responses. Although Mode--5 failure responses are much
less likely to occur than those that result in impacts near the flight line, risk-analysis studies are incomplete without
them. This report shows how Impacts from Mode-6 failures are modeled in program DAMP. The impact density
function used for this purpose contains two shaping constants that control the rate at which the density function
drops In value as the angular deviation from the flight line and the impact range increase. Certain Mode--5
•malfunctions are simulated, and the two shaping constants then chosen by trial and error so that impacts from the
simulated malfunctions and the theoretical density function are in close agreement. An appendix to the report
contains alisting and brief narrative failure history of the A~as, Delta, and Titan missile and space-vehicle launches
from the Eastern and Western Ranges from the beginning of each program through August 1996. Each entry
gives the vehicle configuration, whether the flight was asuccess, the flight phase in which any anomalous behavior
occurred, and aclassification of vehicl~ behavior in accordance with defined failure-response modes.
14. SUBJECT TERMS 15. NUMBER OF PAGES·
launch risk, unlikely failure modeling, booster failure probabilities 180
16. PRICE CODE
17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT
OF REPORT OF THIS PAGE OF ABSTRACT
Unclassified lJnclassified lnclasslfled SAR
NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89)
Prescribed by AIIISI Std. Z39-18
298·102
Abstract
Missile and space-vehicle performance histories contain many examples of failures that
cause, or have the potential to cause, significant vehicle deviations from the intended
flight line. In RTI's risk-analysis program, DAMP, such failures are referred to as
Mode-5 failure responses. Although Mode-5 failure responses are much less likely to
occur than those that result in impacts near the flight line, risk-analysis studies are
•incomplete without them. This report shows how impacts from Mode-5 failures are
modeled in program DAMP. The impact density function used for this purpose
contains two shaping constants that control the rate at which the density function drops
in value as the angular deviation from the flight line and the impact range increase.
Certain Mode-5 malfunctions are simulated, and the two shaping constants then chosen
by trial and error so that impacts from the simulated malfunctions and the theoretical
density function are in close agreement.
An appendix to the report contains a listing and brief narrative failure history of the
Atlas, Delta, and Titan missile and space-vehicle launches from the Eastern and
Western Ranges from the beginning of each program through August 1996. Each entry
gives the vehicle configuration, whether the flight was a success, the flight phase in
which any anomalous behavior occurred, and a classification of vehicle behavior in
accordance with defined failure-response modes. Various filtering or data weighting
techniques are described. The empirical data are then filtered to estimate (1) failure
probabilities for Atlas, Delta, and Titan, and (2) percentages of future failures that will
result in Mode-5 (and other Mode) responses.
9/10/96 RTI
Table of Contents ·
1. Introduction............................................................................................................................... 1
2. Examples Showing Need for Mode 5 ................................................................................ 3
3. Understanding the Mode-5 Failure Response ................................................................... 7
3.1 Effects of Mode-5 Shaping Consta.nts................................. ".....................................-...... 9
3.2 Effects of Shaping Constant on DAMP Results ........................................................ 9
4. Methodology for Assessing Failure Probabilities ........................................................... 13
4.1 The Parts-Analysis Approach .................................................................................. 13'-
4.2 The Empirical Approach .......................................................................................... 15
5. Computation of Failure Probabilities ............................................................................... 16
5.1 Overall Failure Probability....................................................................................... 16
5.2 Relative and Absolute Probabilities for Response Modes ..................................... 24
5.3 Relative Probability of Tumble for Response-Modes 3 and 4 ............................... 30
6. Shaping Constants Through Simulation .......................................................................... 31
6.1 Malfunction Tum. Simulations...........•...................................................................... 31
6.1.1 Random-Attitu.de Failures ...............-............................................................... 31
6.1.2 Slow-Tum Failures ........................................................................................... 32
6.1.3 Factors Affecting Malfunction-Tum Results ................................................ 33
6.1.4 Malfunction-Tum Results for Atlas IIAS ...................................................... 35
6.2 Shaping Constants for Atlas IIAS ............................................................................ 37
6.2.1 Optimum Mode-5 Shaping Constants ........................................................... 37
6.2.2 Launch-Area Mode-5 Risks ............................................................................ 49
6.2.3 Effects of Mode-5 Constants on Ship-Hit Contours ..................................... 51 I
6.2.4 Range Distributions of Theoretical and Simulated Impacts........................ 58
6.3 Shaping Constants for Delta-GEM .......................................................................... 60
6.3.1 Optimum Mode-5 Shaping Constants ........................................................... 61
6.3.2 Launch-Area Mode-5 Risks ............................................................................ 64
6.4 Shaping Constants for Titan IV................................................................................ 65
6.5 Shaping Constants for LLVl .................................................................................... 69
6.6 Shaping Constants for Other Launch Vehicles ....................................................... 72
7. Potential Future Investigations ......................................................................................... 73
8. Summarv:
., ............................................................................................................................ 74
9/10/96 ii RTI
Appendix A. Failure Response Modes in Program DAMP ............................................... 79
Appendix B. Shaping-Constant Effects on Mode-5 Impact Distributions ........................ 81
Appendix C. Filter Characteristics ....................................................................................... 90
Appendix D. Launch and Performance Histories .............................................................. 96
D.1 Basic Data ................................................................................................................. 96
D.1.1 Data Sources ................................................................................................................................................................... 96
D.1.2 Assignment of Failure-Response Modes...................................................... 98
D.1.3 Assignment of Flight Phase.......................................... ~ ....................................................................... 98
D.1.4 Representative Configurations ................................................................... 100
D.2 Atlas Launch and Performance History .............................................................. 101
D.2.1 A'tlas Launch History ..................................................................................................... 103
D.2.2 Atlas Failure Narratives ........... ~ .................................................................... 115
D.3 Delta Launch and Performance History .............................................................. 133
D.3.1 Delta Launch History................................................................................... 136
D.3.2 Delta Failure Narratives .............................................................................. 142
D.4 Titan Launch and Performance History .............................................................. 146
D.4.1 Titan Launch History ................................................................................... 149
D.4.2 Titan Failure Narratives .............................................................................. 157
D.5 Thor Launch and Performance History (Not Including Delta) ......................... 164
D.5.1 Thor and Thor-Boosted Launch History .................................................... 164
D.5.2 Thor and Thor-Boosted Failure Narratives ............................................... 167
References ............................................................................................................................. 171
9/10/96 iii RTI
Table of Figures
Figure 1. Joust Impact Trace Showing a Mode-5 Failure Response ....................................6
Figure 2. Atlas IIAS Risk Contours for Inner-Ear Injury with A = 3.0.............................. 11
Figure 3. Atlas IIAS Risk Contours for Inner-Ear Injury with A = 3.5.............................. 12
Figure 4. Filter Factor Results for Representative Configurations of Atlas ...................... 23
Figure 5. Combined Random-Attitude and Slow-Tum Results ........................................ 36
Figure 6. Atlas IIAS Breakup Percentages for Random-Attitude Tums ........................... 37
Figure 7. Atlas HAS Impacts with No Breakup ........................................................ ~ ........ 39
Figure 8. Atlas IIAS Impacts with Breakup ......................................................................... 40
Figure 9. Atlas IIAS Simulation Results with B = 1,000 ..................................................... 42
Figure 10. Atlas IIAS Simulation Results with B = 50,000.................................................. 44
Figure 11. Atlas HAS Simulation Results with B = 100,000................................................ 45
Figure 12. Atlas HAS Simulation Results with B = 500,000................................................ 46
Figure 13. Atlas HAS Simulation·Results with B = 5,000,000............................................. 47
Figure 14. Effects of Breakup q-alpha on A for Atlas IIAS ................................................ 49
Figure 15. Mode-5 Density-Function Values at Three Miles ............................................. 51
Figure 16. Atlas IIAS Mode-5 Ship-Hit Contours with A= 3.00 ....................................... 53
Figure 17. Atlas IIAS All-Mode Ship-Hit Contours with A = 3.00.................................... 54
Figure 18. Atlas IIAS Mode-5 Ship-Hit Contours with A= 3.45 ....................................... 55
Figure 19. Atlas IIAS All-Mode Ship-Hit Contours with A= 3.45.................................... 56
Figure 20. Atlas IIAS Mode-5 Ship-Hit Contours with A = 6.30 ....................................... 57
Figure 21. Atlas IIAS All-Mode Ship-Hit Contours with A = 6.30.................................... 58
Figure 22. Impact-Range Distributions .................................................................................. 59
Figure 23. Delta-GEM Breakup· Percentages ....................................................................... 61
Figure 24. Delta-GEM Simulation Results with B ==-1,000.................................................. 62
Figure 25. Delta-GEM Simulation Results with Best-Fit Shaping Constants ................... 63
Figure 26. Titctn·IV Breakup Percentages ................................................................................ 65
Figure 27. Titan·Simulation Results with B = 1,000 ............................................................ 66
Figure 28. Titan Simulation Results with Best-Fit Shaping Constants.............................. 67
Figure 29. LLVl Breakup Percentages ..................................................................................................................... 69
Figure 30. LLVl Simulation Results with B = l,000............................................................ 70
9/10/96 iv RTI
Figure 31. LLVl Simulation Results with Best-Fit Shaping Constants ............................. 71
Figure 32. £-Ratios for Ranges from 1 to 25 Miles .............................................................. 86
Figure 33. Percentage of Impacts Between Flight Line and Any Radial .......................... 87
Figure 34. Percentage of Impacts in 5-Degree Sectors ........................................................ 88
Figure 35. Exponential Weights for Fading-Memory Filters ............................................. 93
Figure 36. Recursive Filter Factor for Last Data Point........................................................ 94
Figure 37, Atlas Launch Summary..................................................................................... 102
Figure 38. Delta Launch Summary." ................................................................................... 135
Figure 39. Titan Launch Summary..................................................................................... 148
Figure 40. Thor Launch Summary ..................................................................................... 164
Table of Tables
Table 1. Effects of Mode-5 Shaping Constant A on Atlas IIA Risks .................................. 10
Table 2. Predicted Failure Probabilities for Representative Configurations .................... 17
Table 3. Predicted Failure Probabilities for All Configurations ........................................ 18
Table 4. Comparison of Weighting Percentages ................................................................. 19
Table 5. Filter Factor Influence on Weighting Percentages ................................................ 21
Table 6. Failure Probabilities for Atlas, Delta, and Titan ................................................... 24
Table 7. Number of Atlas Failures - All Configurations (532 Flights) .............................. 25
Table 8. Number of Delta Failures-All Configurations (232 Flights).............................. 25
Table 9. Number of Titan Failures - All Configurations (337 Flights) .............................. 25
Table 10. Number of Eastern-Range Thor Failures (85 Flights) ........................................ 25
Table 11. Number of Failures for All Vehicles (1186 Flights)............................................ 26
Table 12. Date of Most Recent Failure ................................................................................. 26
Table 13. Percentage Weighting for Sample of 1186 Launches ......................................... 27
Table 14. Response-Mode Occurrence Percentages ............................................................ 27
Table 15. Recommended Response-Mode Percentages for Flight Phases O- 2................ 28
Table 16. Recommended Response-Mode Percentages for Flight Phases O- 1................ 29
Table 17. Absolute Failure Probabilities for Response Modes 1 - 5 .................................. 29
Table 18. Percent of Response Modes 3 and 4 That Tumble .............................................. 30
9/10/96 V
Table 19. Sample Impact Distribution for Atlas IIAS- with No Breakup .......................... 41
Table 20. Shaping Constants for Atlas IIAS......................................................................... 48
Table 21. Shaping Constants and Related Risks for Atlas HAS-......................................... 50
Table 22. Best-Fit Conditions for Atlas IIAS............................................. :.......................... 52
Table 23. Shaping Constants and Related Risks for Delta-GEM ....................................... 64
Table 24. Shaping Consta.nts for Titan IV ............................................................................ 68
Table 25. Shaping Constants for LLVl ................................................................................. 72
Table 26. Summary of A Values for B = 1,000................. ;................................................... 72-
Table 27. Failure Probabilities for Atlas, Delta, and Titan ................................................. 75
Table 28. Recommended Response-Mode Percentages for Flight Phases O-2 ................. 75~
Table 29. Recommended Response-Mode Percentages for Flight Phases O- 1................ 75
Table 30. Absolute Failure Probabilities for Response Modes 1 - 5 .................................. 76
Table 31. Summary of A Values for B = 1,000..................................................................•... 77
Table 32. Summary of Optimum·Mode-5 Shaping Constants ........................................... 77
Table 33. Effect on £-Ratio-of Varying Mode-5 Constant A {B = 1000) - Part 1 ................ 82
Table 34. Effect on £-Ratio-of Varying Mode-5 Constant A {B = 1000) - Part 2 ................ 83
Table 35. Effect on £-Ratio-of Varying Mode-5 Constant B {A = 3) - Part 1 ...................... 84
Table 36. Effect on £-Ratio-of Varying Mode-5 Constant B {A= 3) - Part 2 ...................... 85
Table 37. Filter Application for Failure Probability............................................................ 95
Table 38. Flight-Phase Defi°:,itions........................................................................................ 99
Table 39. Flight Phases by Launch Vehicle ......................................................................... 99
Table 40. Summary of Atlas Vehicle Configurations ....................................................... 101
Table 41. Atlas Launch History ...........................................................•............................... 103
•Table 42. Summary of Delta Vehicle Configurations ....................................................... 133
Table 43. Delta Launch History .......................................................................................... 136
Table 44. Summary of Titan Vehicle Configurations ....................................................... 147 .
Table 45. Titan Launch History .......................................................................................... 149
Table 46. Thor Launch History ........................................................................................... 165
9/10/96 Vl RTI
1. Introduction
The debris from most launch vehicles that fail catastrophically tend to impact close to the
intended flight line. Typical failures that produce such results are premature thrust
termination, stage ignition failure, tank rupture or explosion, or rapid out-of-control
tumble. Less likely malfunctions may cause a vehicle to execute a sustained turn away
from the flight line. Examples are control failures that cause the rocket engine to lock in a
fixed position near null, or failures leading to erroneous orientation of the guidance
platform. Such failures should not be ignored, since they may produce nearly all or a
significant part of the risks to population centers that are more than a mile or so uprange or
many miles away from the flight line. Consequently, RTI has been tasked to estimate the
probabilities of occurrence of these less-likely failures, and to determine optimum values
for the shaping constants of the associated impact-density function
RTI has developed a prototype risk-analysis program (1) to analyze the level of risk in the
launch area when ballistic missiles and space vehicles are launched, and (2) to provide
guidelines for launch operations and launch-area risk management. This program, "facility
DAMage and Personnel injury" (DAMP), uses information about the launch vehicle, its
trajectory and failure responses, and facilities and populations in the launch area to estimate
hit probabilities and casualty expectations. When a missile or space vehicle malfunctions,
people and facilities may be subjected to significant risks from falling inert debris, or from
overpressures and secondary debris produced by a stage, component, or large propellant
chunk that explodes on impact. Although fire, toxic materials, and radiation may also
subject personnel to significant danger, these hazards are not addressed in program DAMP.
Hazards are greatest in the launch area and along the intended flight line, but lesser
hazards exist throughout the area inside the impact limit lines. Small hazards exist even
outside these lines if the flight termination system fails or other unlikely events occur.
In computing launch-area risks, DAMP makes no attempt to model vehicle failures per
se. A list of possible failures for any vehicle would be extensive, and variations in
failures from vehicle to vehicle would complicate the modeling process. Instead,
DAMP models failure responses. Regardless of the exact nature of the failures that can
occur, there are only six possible response modes that affect risks on the ground, five
for failure responses, and one to model the behavior of a normal vehicle. The six
modes are described in Appendix A. It can be seen from the descriptions that impacts
resulting from failure-response Modes 1, 2, and 3 occur at most a mile or two from the
launch point, while those from Mode 4 can only occur near the flight line, even though the
vehicle may tumble before breakup or destruct. Although the hazards outside the launch
area and away from the flight line may be small, vehicle flight tests through the years have
demonstrated that finite hazards do exist in these areas. Such hazards are due almost
entirely to Mode-5 failure responses, even through the probability of a Mode-5 failure may
be only a small part of the total failure probability. The Mode-5 failure-response,
theoretical though it is, was developed to reflect the facts that: (1) unlikely vehicle failures
9/10/96 1 RTI
can cause impacts uprange or well away from the intended flight line, and (2) some vehicle
failures cannot logically be classified as Response Modes 1, 2, 3, or 4.
In- keeping with the above, the Mode-5 impact-density function was developed with the
characteristics listed below. The function, which fills the void left by Modes 1 through 4, is
sufficiently robust to include all possible impacts, yet seemingly comports with observed
test results.
(1) Impacts can occur in any direction from the launch point and at any range within
the vehicle's energy capabilities.
(2) At any given impact range from the launch point, the likelihood of impact
decreases as the angular deviation from the flight line increases, becoming least.
likely in the uprange direction. For any fixed angular deviation from the flight
line, the likelihood of impact decreases as the impact range increases.
(3) At fixed impact ranges near the launch point, the impact density function changes
gradually as the impact direction swings 180° from downrange to uprange. As
the impact range increases, the decrease in the density function becomes
progressively more and more rapid with change in impact direction. In other
words, the greater the impact range, the more rapidly the density function
changes with angular deviation from the flight line. •
As modeled in DAMP, the effects of destruct action on the Mode-5 density function are
accounted for in the launch area by supplementing impacts inside the impact limit lines
with those that would occur outside the impact limit lines if no destruct action were taken.
The Mode-5 failure-response methodology was fully developed in an earlier RTI report111•
As pointed ·out there, the shape of the impact density function can be controlled somewhat
through the selection of shaping constants that appear in the defining equation Intuition
suggests that the constants should be vehicle dependent, since (1) ruggedly built missiles
would, after a malfunction, be more likely to impact well away from the flight line than
would a fragile space vehicle that tends to break up before deviating significantly; and
.(2) certain vehicles, after a malfunction, tend to stabilize and •continue thrusting at large
angles of attack, while other vehicles that experience similar malfunctions tend to tumble.
Hit probabilities computed by-program DAMP for targets located more than two miles or
so uprange from the pad or more than a few miles from the flight line, are due almost
entirely to the Mode-5 impact-density function Thus, the assumed probability of
occurrence of a Mode-5 response as well as the selected Mode-5 constants are of
considerable importance.
The tasking for this. study is set _forth as Task No. 10/95-77, Paragraph 2.0, of Contract
FO4703-91-C-0112. The primary purpose of the tasking is: "Perform a study to
determine the best values for Mode-5 failure probability and the Mode-5 density-
function shaping constant A." Although not explicitly included in the statement of work,
the study also develops absolute failure probabilities for Atlas, Delta, and Titan, and
9/10/% 2 RTI
relative probabilities of occurrence for all failure-response modes for these vehicles, LLVl,
and other new launch systems.
Although it may be reasonable to establish the relative probability of occurrence of a
Mode-5 failure response by empirical means, the number of Mode-5 failures is too small to
have any hope of establishing accurate values for the shaping constants from this sample
alone. Inadequate descriptions of vehicle behavior in the available historical records and
uncertainty in impact location following a malfunction add to the difficulty of classifying
failure responses. In view of the limited data available for vehicles that have experienced
Mode-5 failures, the values chosen for the Mode-5 constants must depend on simulations of
vehicle behavior following failure.
2. Examples Showing Need for Mode 5
The need for a Mode-5 response or some similar response mode (or a multiplicity of other
response modes) can be seen from the following vehicle performance descriptions extracted
from Appendix D:
(1) Atlas BE, 24 Jan 61. Missile stability was lost at about 161 seconds, some 30
seconds after BECO, probably due to failure of the servo-amplifier power supply.
The sustainer engine shut down at 248 seconds, and the vernier engines about 10
seconds later. Impact occurred 1316 miles downrange and 215 miles crossrange. •
(2) Titan M-4, 6 Oct 61. A one-bit error in the W velocity accumulation caused impact
86 miles short and 14 miles right of target.
(3) Atlas 145D (Mariner R-1), 22 July 62. Booster stage and flight appeared normal
until after booster staging at guidance enable at about 157 seconds. Operation of
guidance rate beacon was intermittent. Due to this and faulty guidance equations,
erroneous guidance commands were given based on invalid rate data. Vehicle
deviations became evident at 172 seconds and continued throughout flight with a
maximum yaw deviation of 60° and pitch deviation of 28° occurring at 270
seconds. The vehicle deviated grossly from the planned trajectory in azimuth and
velocity, and executed abnormal maneuvers in pitch and yaw. The missile was
destroyed by the RSO at 293.5 seconds, some 12 seconds after SECO.
(4) Atlas SLV-3 (GTA-9), 17 May 66. Vehicle became unstable when B2 pitch control
was lost at 121 seconds. Loss of pitch control resulted in a pitch-down maneuver
much greater than 90°. Guidance control was lost at 132 seconds. After BECO,
the vehicle stabilized in an abnormal attitude. Although the vehicle did not
follow the planned trajectory, SECO (at 280 seconds), VECO (at 298 seconds), and
Agena separation occurred normally from programmer commands.
(5) Atlas 95F (ABRES/AFSC), 3 May 68. Immediately after liftoff the telemetered roll
and yaw rates indicated that the missile was erratic. During the first 10 seconds of
flight the missile yawed hard to the left. It then began a hard yaw to the right,
9/10/96 3 RTI
crossed over the flight line and continued toward the right destruct line. Shortly
thereafter the missile apparently pitched up violently and the HP began moving
back toward the beach. The missile was destructed at about 45 seconds when the
altitude was about 14,000 feet and the downrange distance about 9 miles. Major
pieces impacted less than a mile offshore, indicating uprange movement of the
impact point during the last part of thrusting flight.
(6) Delta Intelsat III, 18 Sep·68. Due to loss of rate gyro, undamped pitch oscillations
began at 20 seconds. A series of violent maneuvers followed at 59 seconds.
During the 13-second period while these maneuvers continued, the vehicle
pitched down some 270°, then up 210°, and then made a large yaw to the left. At
72 seconds the vehicle regained control and flew stably in a down and leftward
direction until 100 seconds. At this time, with the main engine against the pitch
and yaw stops, the destabilizing aerodynamic forces became so· large that quasi-
control could no longer be maintained. The first stage broke up at 103 seconds.
The second stage was destroyed by the RSO at 110.6 seconds. Major pieces
impacted about 12 miles downrange and 2 miles left of the flight line.
(7) Delta Pioneer E, 27 Aug 69. First-stage hydraulics system failed a few seconds
before first-~tage burnout (MECO). The vehicle pitched down, yawed left, rolled
counterclockwise driving all gyros off limits, and then tumbled. Second-stage
separation and ignition occurred while the vehicle was out of control. After about
20 seconds, the second stage regained control in a yaw-right, pitch-up attitude. It
flew stably in this attitude for about 240 seconds until destroyed by the safety
officer at T+484 seconds.
(8) Atlas 68E, 8 Dec 80. Flight appeared normal until 102.7 seconds when the lube oil
pressure on the B2 booster engine suddenly dropped. At 120.1 seconds, the
engine shut down, followed 385 msec later by guidance shutdown of the Bl
engine. The asymmetric thrust during shutdown caused yaw and roll rates that
the flight-control system could not correct. As a result, attitude control was lost
and the thrusting sustainer pivoted the missile to a retrofire attitude before the
vehicle could be stabilized: After the booster package was jettisoned, the missile
was stabilized and decelerating in the retrofire mode by 148 seconds. The
sustainer continued thrusting in this attitude until 282.9 seconds when reentry
heating apparently caused sustainer shutdown and vehicle.breakup.
9/10/96 4 RTI
It is obvious from the response-mode definitions in Appendix A that none of the described
vehicle failures can be considered as a Mode 1, 2, or 3 response, or a Mode-4 on-trajectory
failure.• Except possibly for (2), it also seems apparent that none can be modeled as either a
rapid tumble or a slow tum.
• Although prompt destruct action during any of the described flights might have resulted in a Mode-4
classification, the safety officer typically needs several seconds to evaluate data after a malfunction.
Quick action is contrary to safety philosophy if impact limit lines are not threatened and the destruct •
system is not at risk, since additional flight time enhances the user's opportunity to pinpoint the
nature of the problem.
9/10/96 5 RTI
A good illustration of a Mode-5 failure response occurred during launch of Prospector
(Joust) on the Eastern Range in-June 1991. The Joust consists of a single-stage Castor IV-A
solid-propellant rocket motor and a payload module. The "vehicle made a radical pitch-up
maneuver due to· aft-skirt structural failure at approximately T+14 Seconds." 121 The
vacuum instantaneous impact trace from the RSO console is shown in Figure 1. If the
safety officer had taken destruct action during the time interval from 18 to 25 seconds,
impact would have been well away from the flight line.
CYIER A
UNCLRSSIFIED IP "AP 1 JOUST1761-R
r20SEC.
+ 3 □ .a + 3 □.□
RLTEP. .. PP.rttE
I. 17B CNH!AVE53
SKIN
ON TRRCK ...
. . . ..... ..._._:,.--25SEC. ON TRACK
1. D DELAY ~• 1 .II DELAY
',• r1BSEC. .::---,---
+· 12 CHEV ..
\"·./
t •
.
~ - • • • •30SEC.
•
15 CHEV
■
19.7 5LO
\
'\
•
....
. . . . . . ~-.
16.3 !iLO
32.2 SltT !II .1 5HT
a. 1 RGT 15SEC. Q.7 LFT
~-2 LOIi ~ 1 LOU
\
\ 78 HDG
625 VEL
2 ALT
l
!
....... -- ..
D. I 1l
. --/ . --, ·- --•-=--.-,,,•' CNTRAVE'i!
SKIN . i ·;
0
I
ON TRRU
0 5 DELAY I .
I
'
ON TRACK
0.5 DELAY
I f i
i
+ 4 GREEN
Figure 1. Joust Impact Trace Showing a Mode-5 Failure Response
As still another example of a Mode-5 failure response, a guided Red Tigress sounding
rocket was launched from Pad 20 at Cape Canaveral on 20 Aug 91. Within a second or
two after clearing the launcher, the rocket made a near 90° right tum, and flew stably in
this direction until destroyed by the safety officer at 23.3 seconds. Pieces impacted
some two or three miles from the launch pad. This failure might have been classified
as a Mode-2 response if destruct action had been taken·shortly after launch.
9/10/96 6 RTI
3. Understanding the Mode-5 Failure Response
Unlike failure response Modes 3 and 4, response Mode 5 (and also Mode 2) is not a direct
function of time from launch. For Modes 3 and 4, the mean point of impact (MPI) for each
debris class is fixed, once the failure time is established. At each instant there is only one
possible location for the :MPI for each debris class. On the other hand, the Mod~S impact-
density function for each debris class consists of a primary part and a secondary
superimposed part. The primary impact-density function accounts for impact variability
due to the erratic flight of the vehicle. It is used to determine the probability that the mean
piece in a debris class resulting from vehicle breakup falls in a given area (say on a building
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