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JOHN F. KENNEDY 
SPACE CENTER 


TR-I193 
September 15, 


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DESIGN STUDY OF ARRESTING GEAR SYSTEM 
FOR RECOVERY OF SPACE SHUTTLE ORBITERS 


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JOHN F. KENNEDY SPACE CENTER, NASA 


TR-1193 


DESIGN STUDY OF ARRESTING GEAR SYSTEM 
FOR RECOVERY OF SPACE SHUTTLE ORBITERS 


This study was performed at the Naval Air Engineering 
Center, Philadelphia, Pennsylvania, 19112 by a field 
activity of the U. S. Naval Air Systems Command. 


The study was authorized and funded by NASA Defense 
Purchase Request No. CC-15969A, dated 23 Feb. 
1972. 


Mr. Preston E. Beck, Space Shuttle Task Group, SP-A, 
Kennedy Space Center, Florida, 32899 was the NASA 
coordinator and technical representative for the study. The 
NASA study team included: 

Mr. L. Junker, KSC (DD-SED-31) 

Mr. S. Ewing, KSC (LS-ENG-32) 

Mr. J. Martin, MSC (ES-4) 

Mr. D. Bourque, MSC (EK) 



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TR-1193 


TABLE OF CONTENTS 


Paragraph Title Page 


1.0 INTRODUCTION 1 

2.0 ASSUMPTIONS 3 

3.0 DISCUSSIONS . 5 

4.0 RECOMMENDATIONS (U.S. Navy Reps.) 9 

4.1 RECOVERY SYSTEM 9 

4.2 MODE OF ENGAGEMENT 9 

4.3 TEST PROGRAM 9 

4.4 ALTERNATE SITE RECOVERY SYSTEMS 9 

5.0 RECOMMENDATIONS (NASA Tech. Reps.) 11 


LIST OF TABLES 


Table Title Page 

1 M-21 Arresting Gear Arrestment History 6 

2 Shorebased Arresting Gear Reliability 7 


APPENDIX A DESIGN AND PERFORMANCE ANALYSIS A-l 

APPENDIX B ENGAGEMENT MODE: TRADE-OFF STUDY B-l 

APPENDIX C RECOVERY SYSTEM DESIGN AND DESCRIPTION ...... C-l 

APPENDIX D TEST PROGRAMS D-l 

APPENDIX E COST SCHEDULES ... E-l 


iii/iv 



TR-1193 


REFERENCES 

A. TR- 1 135 , December 1, 1971. 

Space Shuttle Recovery Requirements 
(Facility/Flight Hardware Interface) 

Preston E. Beck, KSC Shuttle Task Group 
Kennedy Space Center (NASA), Florida 32899 

B. TR-1125, August 1,1971 

Feasibility of Arrestment of Space Shuttle Vehicles After Landing 
Preston E. Beck, KSC Shuttle Task Group 
Kennedy Space Center (NASA), Florida 32899 


v/vi 



TR-1193 


1.0 INTRODUCTION 

The National Aeronautics and Space Administration (NASA) is engaged in the 
development of a reusable space shuttle that can be used for a series of missions instead 
of the single operation presently being performed. Reusability of the shuttle orbiter is 
based upon landing the vehicles on a runway similar to that used by conventional air- 
craft on the completion of each mission. Because of the limited number of shuttle 
orbiters, cost, and crew safety, the use of emergency arrestment techniques is being 
considered as a backup system to preclude runway overrun accidents involving the 
shuttle orbiter in much the same manner as emergency arresting systems are being 
employed by military aircraft. 

Present concepts of the orbiter design (not presently fixed) indicate the vehicle 
size, weight, and speed are significantly greater than any current type of military air- 
craft using an arresting system(s), and exceed, by far, the capabilities of existing 
test facilities. This technical report presents a plan for the design, manufacture, 
development, test, and production of an emergency arrestment system for the recovery 
of shuttle orbiters and also includes time and cost estimates for such a system. Due 
to system testing being a major cost area several optional test programs are discussed. 


1/2 



TR-1193 


2.0 ASSUMPTIONS 

2.1 The first step of the study was fixing operational requirements of the shuttle 
orbiters so that arresting gear design criteria could be established. While these re- 
quirements are subject to change as the orbiter design is finalized 7 it was assumed 
that: 


a. The degree of the changes in the landing velocities and weights will be 
small and the resulting effects on study results will be minor. 

b. The design of the system should be based on the maximum energy engaging 
conditions contained in item c . This procedure does not significantly affect overall cost 
of the program and precludes designing a system that might prove to be inadequate at 
some future date. Details of the design optimization are contained in Appendix A. 

c. Parameters for determining the most suitable type and size of energy absorber 
for this application and in sizing of the purchase member/ storage, and drive components 
are as follows: 

(1) Maximum vehicle weight and corresponding maximum velocity: < 

(a) Orbiter Mode; landing, 195,000 lbs., 180 knots. 

(b) Ferry Mode; aborted takeoff, 220,000 lbs. , 220 knots. 

(c) Ferry Mode; future growth, 275,000 lbs., 220 knots. 

(2) Minimum vehicle weight; 150,000 lbs. 

(3) Vehicle deceleration limits; minimized insofar as practical, one to two 
g's preferred. 

(4) Arresting gear runout limit; a maximum of approximately 2,000 feet 
preferred, to be determined by arresting gear design. 

d. Parameters affecting design of engaging system, installation, configuration, 
and ancillary equipment are as follows: 

(1) Mode of Operation; emergency, backup system only. 

(2) Mode of Engagement; subject of tradeoff study, three methods considered 

(a) Hook/Pendant. 

(b) Barricade. 

(c) Landing Gear Entanglement. 


3 



TR-1193 


(3) System Recycle Time; since booster recovery is not p!anned,cycle 
time is not critical; approximately one hour to clear runway for use is acceptable. 

(4) Retraction Power Source; electricity will be made available and is 

preferred. 

(5) Runway Width; 200 ft. minimum, 400 ft. maximum. 

(6) Other Installation Requirements; consistent with standard Navy 

installation. 

(7) Range of Environmental Conditions; California and Florida. 

(8) Off-Center Engaging Distance; to be demonstrated by test, 1/4 runway 
span for design and test purposes. 

(9) Bi-Directional Capability Requirement; none, no approach end engage- 
ments planned. 

(10) Size and Weight Limits (Components); compatible with cargo compartment 
of C-5A aircraft. 

(11) Test Requirement; system must absorb specified kinetic energy and main- 
tain a minimum safety factor of 1.2 on any component. 

(12) Estimated Date First System Required on Site; available schedules 
indicate initial flight test of orbiter will occur approximately in December 1975. 

(13) Total Number of Systems (To be Procured); five to eight. 


4 



TR-1193 


3.0 DISCUSSION 

The United States Navy has employed arresting gear systems as a primary method 
of restraining and stopping aircraft following the landing since 1911. The Navy has 
gained valuable and quite extensive experience with arresting gear systems, with parti- 
cular emphasis being placed on the experience attained since 1942. The arresting 
gear systems developed by the Navy have exhibited an exceptionally high rate of relia- 
bility as shown in Tables 1 and 2. 

Statistical data gathered over an extended period of time indicates that the tail 
hook arresting gear system method has experienced the highest degree of reliability as 
compared to other types of systems such as; net and landing gear entanglement systems. 
Installation of a landing gear hook on aircraft or orbiters (Reference A) increases the 
overall vehicle weight as a result of greater strength requirements in the flight hardware. 
The Navy accepts the increased weight penalty in preference to a compromise in relia- 
bility since any significant number of arrestment failures during landing operations is 
totally unacceptable. 

Realizing that several types of aircraft can use the same arresting equipment the 
Navy manrates the flight hardware and the arresting gear system prior to the system be- 
coming operational. Qualification testing of the system includes dead load testing to the 
highest energy level and actual engagements under test conditions using the flight ve- 
hicle(s) that will employ the system operationally. Full scale testing such as this has 
been found necessary, through experience, to ensure a high level of reliability. 

« 

The use of an arresting gear system in the Space Shuttle program is being con- 
sidered for use as a backup system for wheel brakes, aerodynamic brakes, drag chutes, 
etc. Thus, this study considers acceptance of lower reliability levels as compared to 
those contained in Table 2 which will enable orbiter design engineers to consider the 
feasibility of little or no increase in weight penalties of the flight hardware and degree 
of limited qualifications of the arresting gear system. 

If future experience indicates that an arresting gear system will be required on a routine 
basis it will become necessary to examine in detail the possibility /necessity of using a 
tail hook(s), and to determine if full scale testing requirements warrant the attendant 
facility costs as existing facilities lack the capacity to handle orbiter energy levels. 


5 



TR-1193 


Table 1. M-21 Arresting Gear Arrestment History* 

TOTAL M-21 Arrestments as of approximately 30 September 1970: 75/794 

(Approx. No.) 

Reported Unsuccessful Arrestments: 

Tape Tucks 26 (Includes Unintentional Tucks at NATF Test Sites) 

Other Tape Failures 6 (Estimated, Approx. 3 Reported) 

Pendant Failures 10 (Estimated, Approx. 4 Reported) 

Other Failures 15 (Estimated, Includes Hubs, Flanges, Connectors, 

Sheaves , etc.) 

TOTAL 57 

RELIABILITY = 75,794 - 57 = 75,737 = .9993 
7577-94 757794 

^System described in KSC TR-1125 


6 



TR-1193 


Table 2. Shorebased Arresting Gear Reliability 


1 

2 

3 

4 

5 

fr-k-hk 


Total Engagements 

All Systems 

E-28 System Only 

Mn nf I inciirrpQcfnl 


All 

■fck 

No. of Dropped 

No. of Hook 

Arrestments Due to 


Shorebased 

E-28 System 

Pendants After 

Skips, Late 

Mechanical Failure 

Year 

Systems 

Only 

Engagement 

Hooks & Drops 

After Engagement** 

1966 

1811 

0 

2 

4 

0 

1967 

2621 

593 

0 

5 

0 

1968 

2961 

712 

0 

6 

0 

1969 

2853 

1258 

0 

3 

0 

1970 

2800 

1395 

2 

3 

0 

TOTAL 

13046 

3958 

4 

21* 

0 ! 


Reliability of Retaining Pendant After Hook Engagement: 

1 - T3M6 = - 99969 

Reliability of Engaging and Retaining Pendant Once Decision to Arrest has been Made: 

1 ' I3OT5 = - 99839 

Reliability of E-28 System to Make Successful Arrestment: 

1 - = 1.00000 


‘^Includes the four in Column 4. 
**Became Operational in 1967. 
***System Described in KSC TR-1125. 


7 















TR-1193 


Appendices A through E contain study results relative to arresting gear systems 
as performed by the Navy; those results are as follows: 

NOTE 

For those who are not familiar with the 
terminology used, refer to Appendix A of 
Reference B for the necessary definitions. 

APPENDIX A. Presents information on a preliminary design for an orbiter 
arresting gear system. 

APPENDIX B. Presents results of a trade-off study of various engagement 
modes of the orbiter with the arresting gear system. Con- 
clusions reached are presented in paragraph 4.0. 

APPENDIX C. Presents a description of a proposed arresting gear system 
for the orbiter. 

APPENDIX D. Presents testing, with the Navy analysis being based upon 
the concept of full scale testing. For the Space Shuttle 
application (backup system) consideration should also be 
given to scale model testing. 

APPENDIX E. Presents the costs and schedules of arresting gear for the 
orbiter. The costs should be very carefully examined as 
they include full scale test costs. The testing costs are 
the highest cost item and are far in excess of manufacturing 
costs. 



TR-1193 


4.0 RECOMMENDATIONS (U. S. Navy Reps.) 

Recommendations made by Navy representatives relative to the use of arresting 
gear systems are contained in paragraphs 4.1 through 4.4. 

4.1 RECOVERY SYSTEM 

The recovery system should be designed for a maximum aircraft runout of 1800 
feet. All major performance requirements will be satisfied by designing the system as 
specified in Appendices A and C of this report. 

4.2 MODE OF ENGAGEMENT 

a. Hook - pendant mode of engagement is recommended. 

b. The increased risk of damage to the aircraft and crew associated with the 
barricade mode of engagement should not be accepted unless weight penalty costjcon- 
siderations prohibit the installation of a hook system in the Space Shuttle, orb iter. 

c. Weight penalty is a cost factor only during orbiter operations of the Space 
Shuttle. For these operations, barricade engagements could be used, if required. 
However, it may be possible to use hook-pendant engagement during ferry mode opera- 
tions of the shuttle if the hook system can be made removable. 

d. Barricade engagement of the vehicle is preferred over landing gear entangle- 
ment if hook-pendant engagement is not possible for either orbiter or ferry operations. 

4.3 TEST PROGRAM 

a. A standard Navy type test program which would test the recovery system 
at maximum possible aircraft engaging energy is recommended. 

b. If cost considerations do not permit conducting the standard program, 
either of two alternate test programs utilizing the existing jet car to provide an energy 
capacity of 280 x 10° ft- lbs is recommended. 

4.4 ALTERNATE SITE RECOVERY SYSTEMS 

a. Permanent or semimobile installations are required to avoid excessive 
delay in availability of the systems when needed. 

b. Final selection of the type of installation should be deferred until the mode 
of engagement and number of alternate landing sites are determined. 


9/10 



TR-1193 


5.0 RECOMMENDATIONS (NASA Tech. Reps.) 

Recommendations made by NASA technical representatives relative to the use 
of arresting gear systems are as follows: 

a. Orbiter design contractor investigate the feasibility/desireability of hook- 
pendant vs. barricade mode of engagement with emphasis on the safety factors. 

b. Landing gear entanglement arresting system not to be considered. 

c. Limit testing to existing facility capabilities through use of scale models. 

d. Conduct program level study to establish requirements, if any, for the 
following: 

(1) Permanent arresting gear installations at locations other than the 
operational sites. 

(2) Portable arresting gear transportable by air to selected locales. 


11/12 



TR-1193 


APPENDIX A 

DESIGN AND PERFORMANCE ANALYSIS 


TABLE OF CONTENTS 


Paragraph Title Page 


1.0 INTRODUCTION A-5 

1.1 PROCEDURE A-5 

1.2 RECOVERY SYSTEM DESCRIPTION A-6 

1.2.1 OPERATION A-6 

1.2.2 COMPONENTS A-9 

1.2.3 COMPONENT DESIGN A-12 

1.3 PERFORMANCE REQUIREMENTS A-12 

1.3.1 ENERGY CAPACITY A-12 

1.3.2 AIRCRAFT DECELERATION a-13 

1.3.3 AIRCRAFT RUNOUT. A-13 

1.3.4 PENDANT and TAPE A-13 

1.4 RESULTS A-13 

1.4.1 SYSTEM 1800 A-13 

1.4.2 SYSTEM 2400. 'a-14 

1.4.3 NYLON vs. STEEL PENDANT A-17 

1.4.4 SYSTEM 1800 vs. SYSTEM 2400 A-17 

1.4.5 COMPONENTS DESIGN A-37 

1.5 RECOMMENDATIONS A-38 

1.6 REFERENCES A-39 


A-l 



TR-1193 
Appendix A 


Figure 

1 

2 

3 

4 

5 

6 

\ 

7 

8 
9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 


LIST OF ILLUSTRATIONS 


Title 


Tape Stack 

Deck Layout 

Arresting Engine 

System N1800, AC Retarding Force/AC Runout-Feet 

System N2400, AC Retarding Force/AC Runout-Feet. ...... 

System 1800 (WT. 275,000 lbs. V 220 knots) AC Retarding 

Force/AC Runout-Feet 

System 1800 (WT. 220,000 lbs. V 220 knots) AC Retarding 

Force/AC Runout-Feet 

System 1800 (WT. 195,000 lbs. V 180 knots) AC Retarding’ 

Force/AC Runout-Feet 

System 1800 (WT. 195,000 lbs. V 180 knots) AC Retarding 

Force/AC Runout-Feet 

System 1800 (WT. 195,000 lbs. V 180 knots)’ Pendant* 

Tension/Time-Seconds 

System 1800 (WT. 195,000 lbs. V 180 knots) Tape 

Tension/Time- Seconds 

System 1800 vs. System 2400 (WT. 270,000 lbs. V *220 

knots) AC Retarding Force/AC Runout-Feet 

System 1800 vs. System 2400 (WT. 220,000 lbs. V 220* 

knots) AC Retarding Force/AC Runout-Feet 

System 1800 vs. System 2400 (WT. 195,000 lbs. V 1*8*0* 

knots) AC Retarding Force/AC Runout-Feet 

System 1800 vs. System 2400 (WT. 195,000 Ibs.V *1*8*0* * 

knots) Tape Tension/Time-Seconds 

System 1800 vs. System 2400 (WT. 195,000 Ibs. V *1*8*0* 

knots) Hydraulic Torque/Time- Seconds 

System 1800 vs. System 2400 (WT. 195,000 lbs*. V *1*8*0* 

knots) RPM/Time- Seconds 

System N2400 and System N1800, Maximum AC Retarding 

Force/AC Engaging Speed-Knots 

System N2400 and System N1800, Steady State Region 
Maximum Pendant Tape Load/AC Engaging Speed- Knots .... 
System N2400 and System N1800, Dynamic Region, Any AC 
Weight, Maximum Pendant Tape Load/AC Engaging 
Speed- Knots 


Page 

A-7 
A- 8 
A- 10 
A- 15 
A- 16 

A-18 

A- 19 

A-20 

A-21 

A-22 

A-23 

A-28 

A-29 

A-30 

A-31 

A-32 

A-33 

A-34 

A- 35 


A-36 



ih cm cn 


TR-1193 
Appendix A 

LIST OF TABLES 

Table Title Page 


System 1800, Nylon Pendant • A~24 

System 1800/ Steel Pendant . A-25 

System 2400/ Nylon Pendant A-26 

System 2400/ Steel Pendant A-27 


A- 3/4 



APPENDIX A 


TR-1193 


DESIGN AND PERFORMANCE ANALYSIS 


1.0 INTRODUCTION 

The objective of this analysis is to design the major components of the recovery 
system and predict how this system will perform under actual operating conditions. 

1.1 PROCEDURE 


The main components of the recovery system are designed to satisfy given per- 
formance requirements. Performance predictions of the system are obtained by mathe- 
matical model computer simulation techniques. The technique yields the theoretical 
response of a specified recovery system to the engagement of an .aircraft. T he d ynamics 
of each major component of the system are described by a set of mathematical equations. 
These equations plus the mathematical descriptions of interactions between components 
and other rules of operation of the system are used to develop a computer program which 
simulates the performance of the actual system. 

The initial conditions are known - at time equals zero the recovery system is at 
rest and the aircraft has a specified weight and speed. Time is advanced in very small 
steps (.001 sec.) , during which the acceleration of all moving components is assumed 
to remain constant and equal to their particular values at the beginning of the time step. 
These new positions and velocities are then used to compute the loads developed and 
accelerations produced on the components. The new acceleratTons are then used for 
predictions in the next time step. Time thus continues until the arrestment is complete. 

The technique yields excellent simulations of systems that can be accurately 
described mathematically, and for systems in which the change in acceleration is not 
large enough to introduce inaccuracies. Aircraft recovery systems such as the one 
designed for the NASA Space Shuttle are basically simple devices, but complete mathe- 
matical description of all components is not possible. Also, during the initial stages 
of the arrestment, the accelerations are changing violently. The technique has, however, 
been shown to yeild accurate simulations of other recovery systems, especially those 
similar in design to this proposed system, during both the dynamic and steady state 
regions of the arrestment. However, the technique has not yet been verified for the high 
kinetic energy conditions required for this design. For these reasons, the procedure 
used in this study is considered capable of producing performance results which permit a 
quantitative analysis in the steady state region of the arrestment, and at least a quali- 
tative analysis in the early "dynamic" region of the arrestment. 


A- 5 



TR-1193 
Appendix A 


Results of the computer simulation program are the histories of the positions, 
velocities, accelerations, loads, etc. of the aircraft and main components of the recovery 
system. The computer-generated performance is identical in form to the instrumented and 
recorded output of a full scale test program of the actual system. Hence, an analysis 
of the results of the computer simulation study is conducted in the same way as if the 
data were from actual tests. 

Components of the recovery system are described by input data to the program, 
and are therefore easily varied. Proper sizing of each major component is accomplished 
so that the resultant system performs as required. 

The study was conducted for hook-pendant mode of engagement only. Simulation 
programs for barricade and landing gear entanglement modes are still in a state ofearly 
development. Recovery systems which are identical except for the engaging member have 
been shown to perform very similarly, especially in the steady state region of the arrest- 
ment. Hence, present design procedure is to assume hook-pendant engagement and conduct 
the computer simulation study. All resulting components, except the pendant, are then 
incorporated into the final design. This technique yields performance predictions appli- 
cable to all engaging systems. 

1.2 RECOVERY SYSTEM DESCRIPTION 

1.2.1 OPERATION. Various aircraft recovery systems were considered. The one 
chosen as most capable of satisfying all design requirements is a tape stack rotary 
hydraulic system similar to the Navy Shorebased emergency gear. (Figure 1) 

This recovery system is composed of an arresting engine on each side of the 
aircraft runway. An engine consists of a rotor and stator enclosed in a housing con- 
tainjng fluid. The rotor is connected by a shaft to a hub on which the purchase tape is 
wound. The free end of the tape of both engines is connected to a single pendant that 
stretches across the runway. 

The aircraft employs the system by engaging the pendant with its hook. 

Tape is pulled off both hubs causing the hubs and rotors to revolve. Fluid resistance to 
the rotor's motion causes a retarding force to be generated in the purchase tape and pen- 
dant which opposes the motion of the aircraft. The kinetic energy of the aircraft is 
dissipated through this process. (Figure 2) 


A— 6 



TR-1193 
Appendix A 


flange outek radius 

R INITIAL VALUE. 



Figure 1. Tape Stack 


deck span — 


Figure 2 . Deck Layout 



TR-1193 
Appendix A 


1.2.2 COMPONENTS. Function and Mathematical Description. 

a. Arresting Engine. 

(1) Hydraulic energy absorber; converts the aircraft's kinetic energy 
into heat energy of the fluid. 

(2) Rotational motion of the rotor generates a fluid flow field which 
retards the rotor's motion. The resistance to rotation, specified as a torque, is propor- 
tional to the speed of the rotor. 

(3) Mathematical description of the arresting engine is provided by 
an-expression relating the speed of the rotor and the torque developed. The mass moment 
of inertia of the rotor must also be specified. (Figure 3) 

b. Tape Reel. 

(1) Provides for purchase tape storage. 

(2) Converts tape payout linear motion to rotary motion of tape stack, 

shaft and rotor. 

(3) Converts torque imposed on the rotor to a linear tape tension load. 

(4) Provides the means for maintaining a relatively constant tape 
tension load throughout the arrestment while torque and speed vary. 

(5) Mathematical description of the tape reel is provided by pro- 
gramming, which calculates the change in outer radius of the tape stack and change in 
mass moment of inertia of the tape remaining on the reel throughout the arrestment. 

Data required to describe a specific tape reel is: 

(a) Tape stack inner radius - hub radius. 

(b) Tape length wound on the reel. 

(c) Tape thickness . 

(d) Tape mass density. 


A- 9 



TR-1193 
Appendix A 



i 


Figure 3. Arresting Engine 



TR-1193 
Appendix A 


(6) Mass moment of inertia of the hub and flanges must also be specified. 

See Figure 1. 

c„ Purchase Members - Pendant and Tape. 

(1) Provide the connection between the aircraft and arresting engine. 

(2) Mathematical description of the purchase members is provided by 
programming, which computes the elongation - load characteristics of these units. The 
mathematical model used for the pendant or tape is a spring anddashpot in parallel. The 
spring stiffness and damping coefficient are calculated for each size pendant and tape. 
Data required to describe a pendant or tape is: 

(a) Mass density. 

(b) Modulus of elasticity . 

(c) Cross sectional size. 

i 

(3) Additional programming, required for mathematical description of the 
pendant and tape, calculates the response of these elastic members to the transverse 
impact imposed by the aircraft hook. The mathematical relationships of cable dynamics 
in an aircraft recovery system environment used to develop this model are detailed in 
reference a„ 

d. Other Moving Components. The mass or mass moment of inertia of all 
moving components of the recovery system must be specified in order to calculate the 
total effective mass accelerated by the aircraft. These components include the deck 
sheave, arresting engine shaft, tape-pendant connector, etc. 

e. Positions and Locations. Mathematical description of the geometry of the 
recovery system must be provided. (Figure 2) Pendant length, deck span and position 
of tape reel relative to the deck sheave must be specified. The geometry used is two 
dimensional; the effects of positional considerations perpendicualr to the deck are assumed 
negligible. 

f. The recovery system is assumed to be symmetrical. Only one-half of the 
system is programmed; the other side is assumed to respond exactly the same. This 
limits simulation to on-center arrestments. 


A- 11 



TR-1193 
Appendix A 

1.2.3 COMPONENT DESIGN. Selection of Type. 

a. The recovery system designed will be used in an emergency mode. 
Operations will be infrequent and scheduled well in advance. Hence, the system need 
not be designed for high cycle operations with components that have long service lives. 1 

b. Arresting Engine. The small ratio of maximum to minimum aircraft 
weight (r = 275000/150000 — 1.8) indicates that a constant torque capacity unit will 
suffice. The design of this unit will be similar to that used in the Navy's E-28 
system. A larger unit with greater torque and energy absorbing capacity will, however, 
be required. The growth potential of this type of energy absorber has been adequately 
demonstrated, providing the proper engine performance should involve no major design 
problems. 


c. Tape. Nylon tape similar in design to the E-28 tape but larger and 
stronger will be used. Coating this tape to improve service life is not required. 

d. Pendant. Two types of pendants will be investigated. They will both 
be of the non-rotating type of construction to minimize reduction in strength due to the 
tendency ol a load carrying pendant to unwind. 

(1) Steel Pendant - steel wire rope - (12 x 6)/(6 x 30) construction. 

(2) Nylon Pendant - nylon rope - 2 in 1 braided construction - poly- 
urethane coated. 

e. Tape Reel. In order to reduce the total moving mass of the system, the 
tape reel will be designed with stationary flanges. 

1.3 PERFORMANCE 'REQUIREMENTS 

1.3.1 ENERGY CAPACITY. The recovery system must operate effectively over 
the following range of aircraft weights and speeds. 

(a) Orbiter Mode. 

Aircraft Weight = 150,000 to 195,000 lbs. 

Engaging Speed - 0 to 180 knots. 

Maximum Kinetic Energy = 280 x 10 6 ft.-lbs. (195K at 180 knots). 


A- 12 



TR-1193 
Appendix A 


(b) Ferry Mode. 

(1) Present Design. 

Aircraft Weight = 150,000 to 220,000 lbs. 

Engaged Speed - 0 to 220 knots. 

NOTE: Maximum aborted take-off speed = 220 knots. 

Maximum Kinetic Energy - 472 x lO^ft. -lbs. (220K at 220 knots). 

(2) Future Expected Weight Growth. 

Possible maximum future growth in aircraft weight = 25% 

Aircraft Weight = 220 ,000 (1.25) = 275 ,000 lbs . 

Maximum Kinetic Energy = 590 x 10^ft.-lbs. (275K at 220 knots.) 

I 

1.3.2 AIRCRAFT DECELERATION. Aircraft deceleration must be minimized. 
Maximum deceleration should be approximately lg Clg = 32 .2ft. /sec. ^). 

1.3.3 AIRCRAFT RUNOUT. Maximum aircraft runout should not exceed 2000 ft. 

This is a tentative limit which may be increased. 

1.3.4 PENDANT and TAPE. Factors of Safety. Factors of safety should be 
maximized. A factor of safety of 2 based on the maximum steady state tension load and 
minimum breaking strength of the purchase member will be acceptable. Factors of safety, 
based on maximum dynamic region loads, that are slightly less than the steady state 
factors will be acceptable, if operational procedures provide that these components be 
discarded after being used once. 

1.3.5 AIRCRAFT RUNWAYWIDTH. Nominal size will be 300 ft., but the recovery 
system should be compatible with runway widths 200 to 400 ft. 

1.4 RESULTS 

Details of component sizes and performance results of both System 1800 and 
System 2400 for various engaging conditions are presented in Tables 1 thru 4 and 
Figures 4 thru 20. The prefix S, as in S1800, denotes a system equipped with a steel 
pendant while the prefix N, as in N1800, denotes a nylon pendant. 

1.4.1 SYSTEM 1800. A computer simulation design study was conducted to 
optimize performance for the maximum engaging conditions expected for the orbiter mode of 
operations. Optimum performance is defined as imposing the minimum retarding force on 


A- 13 



TR-1193 
Appendix A 


the aircraft while dissipating the kinetic energy within a fixed runout distance. Mini- 
mizing the loads and accelerations will minimize the size of the hook structure and result 
in the smallest weight addition to the aircraft. Minimizing this weight penalty is of 
prime importance for the space shuttle when operating as an orbiter. 

This optimized system is designated System 1800. 

Aircraft runout required is 1800 ft. 

Maximum aircraft deceleration is approximately l.Og's for an engaging 
speed of 180 knots with aircraft weights up to 195,000 lbs. Lower speeds will re- 
sult in lower decelerations. 

System 1800 incapable of safely arresting the higher speed and weight 
conditions associated with the ferry mode of operations, including the 25% future weight 
growth possibility. 

Aircraft runout required is 1800 ft. 

Maximum aircraft deceleration is approximately 1.5q’s for an eng aging 
speed of 220 knots and and aircraft weights up to 275,000 lbs. (Figure 4.) 

1.4.2 SYSTEM 2400. A study was also conducted with emphasis on satisfying 
the deceleration requirements for maximum engaging conditions of ferry mode operations. 

This system is called System 2400. 

Aircraft runout required is 2400 ft. 

Maximum aircraft deceleration is approximately l.Og's for an' engaging 
speed of 220 knots and aircraft weights up to 275,000 lbs. Lower speeds will result 
in lower decelerations. 

System 2400 also provides also provides satisfactory performance with 
the orbiter mode maximum conditions. 

Aircraft runout is 2400 ft. 

Maximum aircraft deceleration is approximately 0.7g's for an engaging 
speed of 180 knots and aircraft weights up to 195,000 lbs. (Figure 5.) 


A- 14 



TR-1193 
Appendix A 














TR-1193 
Appendix A 









TR-1193 
Appendix A 


1.4.3 NYLON vs. STEEL PENDANT 

a. Refer to Figures 6 thru 11 and Tables 1 thru 4. 

b. The nylon pendant significantly reduces the aircraft retarding force and 
purchase member load oscillations in the dynamic region of the arrestment,, 

c. Peak loads, especially in the dynamic region, are lower with the nylon 

pendant. 

d. Maximum pendant and tape loads occur in the steady state region of 
the arrestment with nylon pendants. Hence, a system with an adequate steady state 
factor of safety will have an adequate dynamic region safety factor. 

e. Maximum pendant and tape loads generally occur in the dynamic region 
of the arrestment with steel pendant systems. This is caused by the stiffness and high 
weight of these pendants. A steel pendant strong enough to provide adequate safety 
factors in the steady state region may be so stiff and heavy that the larger loads produced 
in the dynamic region would result in inadequate safety factors in this region. 

_ . . I 

f. Nylon pendant system factor (s) of safety are greater than those for 
steel pendant systems in both the dynamic and steady state regions, for all design en- 
gaging conditions. 

g . There is no need to change pendant or tape size to accommodate the 
different aircraft engaging conditions with a nylon pendant system. Steel pendant sys- 
tems will, however, require changes in pendant size to accommodate the different aircraft 
weights. System S2400 will require changes in both pendant and tape. (Table 4) 

h. In order to limit dynamic region loads with steel pendant systems, the 
deck span (distance between runway deck sheaves) must be at least 400 ft. Deck span 
with nylon pendant systems can be tailored to fit existing runway widths. 

i. Conclusion. The nylon pendant is superior to the steel pendant for 
this application. 

1.4.4 SYSTEM 1800 vs. SYSTEM 2400. 


a. Refer to Figures 12 thru 20 and Tables 1 thru 4. 


b. The main differences in performance previously mentioned, are: 


Runout 

Max Deceleration Orbiter Mode 
Max Deceleration Ferry Mode 


System 1800 
1800 ft. 
l.Og 
1.5g 


System 2400 
2400 ft. 
0,7g 
1 Og 


A- 17 





ooix /ssh)- 30a 


TR-1193 
Appendix A 



























Figure 10. System 1800 (WT. 195,000 lbs. V 180 knots) 
Pendant Tension/Time-Seconds 










TR-1193 
Appendix A 












TR-1193 
Appendix A 


Table 1. System 1800 , Nylon Pendant 

System N1800 
Design Runout 1800 ft. 


Design 

1. Energy Absorber 

a. Rotor Diameter - 64 inches 

b. Torque Capacity - 1.05 ft.-lbs,/(rpm) 

c. Energy Capacity - 300 x 10® ft, -lbs, 

2. Tape Reel 

a. Hub Inner Radius - 10.5 in. 

b. Flanges - Stationary -Diameter - 8.5 ft. 


3. Pendant , „ ' , 

a. Type - Nylon - 2 in 1 Braided Construction - Polyurethane Coated 

b. Length - 290 ft. 


4. Tape 

a. Type - Nylon - Uncoated 

b. Length - 1700 ft. 


5. Deck Span - 200 to 400 ft. 


performance 

Orbltor Mode 
Max Landing 

Ferry Mode 
Max Abort 
Takeoff 

Ferry Mode 
Max Future 
Growth 

1. 

Aircraft Weight - lbs. 

195,000 

220,000 

275,000 

2. 

Aircraft Engaging Speed - knots 

180 

220 

220 

3. 

Aircraft Kinetic Energy - ft. -lbs. 

280 x 10 6 

472 x 10 6 

590 x 10 6 

4. 

Max Deceleration - g’s 

1.0 

1.42 

1.38 

5, 

Max Retarding Force - lbs. 

195,000 

312,000 

379,000 

6. 

Max Runout - ft. 

1,750 

1,800 

1,860 

7. 

Pendant 

a. Size Diameter - inches 

3-7/8 

3-7/8 

3-7/8 


b. Breaking Strength - lbs. 

400,000 

400,000 

400,000 


c. Factor of Safety 
(1) Dynamic 

4.2 

3.2 

3.2 


(2) Steady State 

4.0 

2.5 

2.1 

8. 

Tape 

a. Size - inches 

18 x .4 

18 x .4 

18 x .4 


b. Breaking Strength - lbs. 

400,000 

400,000 

400,000 


o. Factor of Safety 
(1) Dynamic 

2.9 

2.2 

2.2 


(2) Steady State 

4.0 

2.5 

2* 1 


A-24 



TR-1193 
Appendix A 


Table 2. System 1800, Steel Pendant 

System SI 800 
Design Runout 1800 ft. 

Design 

1. Energy Absorber 

a. Rotor Diameter - 64 inches 

b 0 Torque Capacity - 1.05 ft. -lbs. /(rpm) 2 

c. Energy Capacity - 300 x 10® ft. -lbs. 

2. Tape Reol 

a. Hub Inner Radius - 10,5 in. 

b. Flanges - Stationary -Diameter - 8.5 ft. 

3„ Pendant 

a. Type - Steel Wire Rope - (12 x 6)/(6 x 30) Construction 

b. Length - 290 ft. 

4. Tape 

a. Type - Nylon - Uncoated 

b. Length - 1700 ft. 


5. Deck Span - 400 ft. minimum 


Performance 

Orbiter Mode 
Max Landing 

Ferry Mode 
Max Abort 
Takeoff 

Ferry Mode 
Max Future 
Growth 

1, Aircraft Weight - lbs. 

195,000 

220,000 

275,000 

2. Aircraft Engaging Spood - knots 

180 

220 

220 

3. Aircraft Kinotlc Energy - ft, -lbs. 

280 x 10 6 

472 x 10 6 

590 x 10 6 

4. Max Deceleration - g's 

1,04 

1.48 

1.45 

5. Max Retarding Force - lbs. 

202,000 

326,000 

398,000 

6. Max Runout - ft. 

1,750 

1,800 

1,860 

7. Pendant 




a. Size Diameter - inches 

1-5/8 

2.0 

2.0 

b„ Broaking Strength - lbs. 

254,000 

384,000 

384,000 

f 

c. Factor of Safety 




(1) Dynamic 

1.7 

1.6 

1.6 

(2) Steady State 

2.4 

2.3 

1.9 

8. Tape 




a. Si 7.0 - inches 

18 x .4 

18 x ,4 

18 x .4 

b. Broaking Strongth «- lbs. 

400,000 

400,000 

400,000 

c. Factor of Safety 




(1) Dynamio 

3.0 

2.1 

2.1 

(2) Steady State 

3.8 

2.4 

2.0 


A-25 



TR-1193 
Appendix A 

Table 3. System 2400, Nylon Pendant 

Sy stem N2400 
Design Runout 2400 ft. 

Design 

1. Energy Absorber 

a. Rotor Diameter - 64 inches 

b. Torque Capacity - 1.05 ft. -lbs. /(rpm) 2 

c. Energy Capacity - 300 x 10® ft. -lbs. 

2. Tape Reel 

a. Hub Inner Radius - 10.5 in. 

b. Flanges - Stationary -Diameter - 10 ft. 

3. Pendant 

a . Type _ Nylon - 2 in 1 Braided Construction - Polyurethane Coated 

b. Length - 290 ft. 

4. Tape 

a. Typo - Nylon - Uncoated 

b. Longth - 2300 ft. 

5. Dock Span - 200 to 400 ft. 


Performance 

Orbiter Mode 
Max Landing 

Ferry Mode 
Max Abort 
Takeoff 

Ferry Mode 
Max Future 
Growth 

1. Aircraft Weight - lbs. 

195,000 

220,000 

275,000 

2. Aircraft Engaging Speed - knots 

180 

220 

220 

3. Aircraft Kinetic Energy - ft. -lbs. 

280 x 10 6 

472 x 10 6 

590 x 10 6 

4. Max Deceleration - g's 

0.68 

1.00 

1.01 

5. Max Retarding Force - lbs. 

133,000 

220,000 

278,000 

6. Max Runout - ft. 

2,320 

2,390 

2,470 

7. Pondant 

a. Size Diameter - Inches 

3-7/8 

3-7/8 

3-7/8 

b. Breaking Strongth - lbs. 

400,000 

400,000 

400,000 

c. Factor of Safoty 
(1) Dynamic 

3.9 

3.0 

3.0 

(2) Steady State 

5.9 

3.5 

2.8 

8. Tape 




a. Size - inches 

18 x .4 

18 x .4 

18 x .4 

b. Breaking Strength - lbs. 

400,000 

400,000 

400,000 

c. Factor of Safety 
(1) Dynamic 

2.8 

2.0 

2.0 

(2) Steady State 

5.9 

3.5 

2.8 


A-26 



TR-1193 
Appendix A 

Table 4. System 2400, Steel Pendant 

System S2400 
Design Runout 2400 ft. 

Design 

1. Energy Absorber 

a. Rotor Diameter - 64 inches 

b. Torque Capacity - 1.05 ft. -lbs. /(rpm) 2 

c. Energy Capacity - 300 x 10 6 ft. -lbs. 

2. Tape Reel 

a. Ilub Inner Radius - 10.5 in. 

b. Flanges - Stationary-Diameter - 10 ft. 

3. Pendant 

a. Type - Steel Wire Rope - (12 x 6)/(6 x 30) Construction 

b. Length - 290 ft. * 

4. Tape 

a. Type - Nylon-Uncoated 

b. Length - 2300 ft. 


5. Deck Span - 400 ft. minimum 


Performance 

Orbitcr Mode 
Max Landing 

Ferry Mode 
Max Abort 
Takeoff 

Ferry Modo 
Max Future 
Growth 

1 . 

Aircraft Weight - lbs. 

195,000 

220,000 

275,000 

2. 

Aircraft Engaging Speed - knots 

180 

220 

220 

3. 

Aircraft Kinetic Energy - ft. -lbs. 

280 x 10 6 

472 x 10 6 

590 x 10 6 

4. 

Max Deceleration - g's 

0.71 

1.03 

1.05 

5. 

Max Retarding Force - lbs. 

138,000 

226,000 

288,000 

G. 

Max Runout - ft. 

2,330 

2,410 

2,480 

7. 

Pendant 

a. Size Diameter - inchos 

1-3/8 

1-5/8 

1-7/8 


b. Breaking Strength - lbs. 

182,000 

254,000 

338,000 


c. Factor of Safety 
(1) Dynamic 

1.9 

1.7 

1.7 


(2) Stoady State 

2.6 

2.2 

2.3 

8 . 

Tape 

i ' 




a. Sizo - inchos 

11 x .4 

11 x .4 

14 x .4 


b. Breaking Strength - lbs. 

246,000 

246,000 

314,000 


c. Factor of Safety 
(1) Dynamic 

3.0 

1.9 

1.9 


(2) Steady State 

3.5 

2.1 

2.1 


A-27 


TR-1193 
Appendix A 



Figure 12. System 1800 vs. System 2400 (WT. 270,000 lbs. V 220 knots) 
AC Retarding Force/AC Runout-Feet 


A-28 




Figure 13. System 1800 vs. System 2400 (WT. 220,000 lbs. V 220 knots) 
AC Retarding Force/AC Runout-Feet 


A-29 


























Figure 16. System 1800 vs. System 2400 (WT. 195,000 lbs. V 180 knots) 
Hydraulic Torque/Time- Seconds 











RPM 


TR-1193 
Appendix A 



Figure 17. System 1800 vs. System 2400 (WT. 195,000 lbs. V 180 knots) 
RPM/Time-Seconds 


A-33 













Figure 19. System N2400 and System N1800, Steady State Region 
Maximum Pendant Tape Load/AC Engaging Speed-Knots 


A- 35 






Figure 20. System N2400 and System N1800, Dynamic Region, Any AC Weight 
Maximum Pendant Tape Load/AC Engaging Speed-Knots 










TR-1193 
Appendix A 


1.4.5 COMPONENTS DESIGN. Selection of size. 

a. Arresting Engine. 

Systems 1800 and 2400 require the same engine. 

Torque Capacity = 1.05 ft.-lbs/(rpm)^. 

Energy Capacity = 300 x 10 6 ft.-lbs. per unit (600 x 10 6 total system.) 

This torque capacity will require a unit with a rotor diameter of 64 inches. Engines of 
this size and torque capacity have been manufactured. These units performed adequately 
during a small test program with limited engaging energy conditions. Maximum tested 
energy absorbed was 180 x 10 6 ft.-lbs. , less than 1/3 the required maximum energy 
capacity of the intended design. However , no major design or development problems are 
expected in attaining this increased energy absorbing capacity. 

b. Tape Reel. 

(1) Systems 1800 and 2400 require the same hub inner radius. 

Hub Radius = 10.5 inches. 

Minimum hub radius allowable is dependent upon the rotor and shaft size and the purchase 
tape size. The rotor and shaft sizes are determined by material strength and the torque 
capacity required. Tape size required determines the smallest radius to which this tape 
can safely be wrapped. A hub radius of 10.5 inches is compatible with the torque capa- 
city and tape sizes required with either system. 

(2) Flange Diameter = 8.5 ft. System 1800 

Flange Diameter = 10 ft. System 2400 

Experience with stationary flanges is limited. Experience with flanges as large as these 
is non-existant, but no major design or development problems are expected. 



Width 

Tape 

Thickness 

Length 

System 

(in.) 

(in.) 

(ft.) 

N or S1800 

18 

0.4 

1700 

N2400 

18 

0.4 

2300 

S2400 

14 

0.4 

2300 

S2400 

11 

0.4 

2300 


A-37 



TR-1183 
Appendix A 


Nylon tapes of 18 x 0.4 cross-sectional size have been successfully manufactured, and 
are available in continuous lengths in excess of 2300 ft. The smaller width tapes 
required for System S2400 should also be readily available. 

d. Pendant 

(1) Nylon Rope. 

Diameter - 3=7/8 inches. Systems N1800 or N2400 
Length 290 ft. for 300 ft. deck span. 

Construction 2 in 1 braided. 

Coating - polyurethane. 

This is a standard "off the shelf" item, readily available in continuous lengths in excess 
of 290 feet. Previous experience with smaller nylon pendants has indicated the perfor- 
mance advantages of this type. Nylon pendants have not gained acceptance in military 
systems due to their short service lives and an inability to establish good replacement 
criteria. These two requirements are not factors for design of the Space Shuttle Recovery 
System; the pendant can be replaced after each arrestment. The hook can be designed 
to accommodate any size pendant. A pendant as large as this may introduce a "rollover" 
problem when the landing gear passes over it, but this problem should be minor. The 
nylon pendant is judged acceptable for this system. 

(2) Steel Wire Rope. 

Diameters - 1-5/8" and 2" System S1800 

Diameter - 1-3/8", 1-5/8" and 1-7/8" System S2400 
Length - 290 feet for 400 ft. deck span. 

Construction - (12 x 6)/(6 x 30) 

Steel wire rope pendants of this construction have been manufactured in only one size - 
1-1/4 inch diameter. However, experience in the manufacture of other types of wire 
• rope indicates that these sizes can readily be built with this construction. Steel wire 
rope pendants are standard with military systems and would be acceptable with the 
Space Shuttle System. 

! .5 RECOMMENDATIONS 

The system should be designed with a nylon pendant. 


A=38 



TR-1193 
Appendix A 


The shorter runout system, N1800, is preferred. Although the loads and 
accelerations are higher than System N2400, they are acceptable. Also, the shorter 
runout system is less likely to incur an aircraft tracking problem. Si nc e Systems N2400 
and N1800 differ only in the minimum flange size required and length of tape wrapped 
on the reel , design for System N2400 . Then by varying the length of tape, any aircraft 
runout less than 2400 ft. can be obtained. The optimum runout will be determined by 
development tests. 

incorporate all components sized by this study into the final design regardless 
of the engagement mode chosen. Replace only the pendant by the barricade net or 
Sanding gear entanglement member. 

1.6 REFERENCES 


Naval Air Engineering Center, Engineering Department (SI) Report, NAEC- 
ENG-6169 "Cable Dynamics" of 27 Dec 1956 by Friebrlch 0. Ringleb. 


A-39/40 



TR-1193 


APPENDIX B 

ENGAGEMENT MODE: TRADE-OFF STUDY 


TABLE OF CONTENTS 


Paragraph Title Page 


1.0 INTRODUCTION B-3 

1.1 ENGAGEMENT MODES EVALUATED B-3 

1.2 PROCEDURE . B-3 

1.3 TRADE-OFF STUDY B-4 

1.3.1 PARAMETERS B-4 

1.3.2 EMPHASIS CURVE B-5 

1.3.3 

1.3.4 ASSIGNING SCORES . . .. B-8 

1.4 RESULTS B-13 


LIST OF TABLES 


T able Title Page 

1 Emphasis Curve Work Sheet B-6 

2 Engagement Mode Trade-Off Study B-14 


B-l/2 



TR-1193 


APPENDIX B 

ENGAGEMENT MODE: TRADE-OFF STUDY 

1.0 INTRODUCTION 

The objective of this study is to determine the proper mode of engaging the air- 
craft and recovery system. All feasible modes of engagement are evaluated, and the 
optimum one chosen. 

1.1 ENGAGEMENT MODES EVALUATED 

a. Hook Pendant Engagement. A hook attached to the aircraft is dragged along 
the runway to pick up a pendant stretched across the deck. 

b. Barricade Engagement. The entire aircraft passes into and is enveloped by 
a nylon net suspended across the runway. 

c. Landing Gear Entanglement. The main landing gear of the aircraft engage a 
pendant/net which must be raised off the deck after the forward landing gear has passed 
over the pendant/net. 

d. It should be noted that the Naval Air Engineering Center has had extensive 
experience in the design, development, test and actual field or aircraft carrier usage of 
each of the three engagement modes studied. This experience was applied in most of 
the areas involved in this evaluation. 

1.2 PROCEDURE 

a. A performance/cost trade-off study was conducted to determine the proper 
mode of engagement. Each engaging system was evaluated on a performance or cost 
basis for several factors pertinent to the aircraft recovery system operation. The 
evaluation of several engaging systems, by a comparison study which includes many 
different factors, results in a complex decision making problem. 

b. An analytical technique, known as the "Emphasis Curve", was used to help 
simplify the problem. The technique gives emphasis to the more important parameters to 
be considered in selecting the proper system, while deemphasizing the less important 
ones. The procedure does not substitute for the judgment of the evaluator; it merely helps 
him to systematize the decision making process by keeping account of all parameters and 
by determining the importance of each in relation to all others. In this way, each 
parameter can be weighted in proportion to its importance. These weighting factors, 
called RIF (Relative Importance Factors), are assigned to each parameter through the 
analysis. 


B-3 



TR-1193 
Appendix B 


c. After determining the importance of each parameter to be used in the evalua- 
tion/ each engaging system is assigned a numerical score, by the evaluator, for each 
parameter. This score is proportional to the degree in which the particular engaging 
system satisfies the requirements of the parameter. 

d. By multiplying each score by the weighting factor assigned for that parameter, 
we generate a table of effective scores for each engaging system and each parameter. 

The effective scores for each engaging system are totaled, and the system with the 
greatest total is the optimum one. 

1.3 TRADE-OFF STUDY 

1.3.1 PARAMETERS. Parameters used in trade-off study are as follows: 

a. Weight penalty - addition to basic aircraft weight caused by modifica- 
tions required to use the engaging system. 

b. Cost of required aircraft modifications - cost to design, develop and 
install any modifications to the aircraft required to use the engaging system. 

c. Technical risk of required aircraft modifications - risk of successfully 
designing and developing a reliable system required to use the engaging system. This 
includes reliability of activating these devices and their operational reliability through- 
out the arrestment. 

d. Engagement reliability - reliability of engaging the recovery system. 

e. Safe arrestment reliability - assuming a successful engagement, this is 
the probability of retaining the engaging member throughout the arrestment without ab- 
normal damage to the vehicle or injury to the crew. 

f. Normal operational damage - assuming a successful arrestment, this is 
normal aircraft damage expected as a result of the engaging device. 

g. Technical risk of engaging device - the risk of designing and developing 
a reliable engaging system. Includes consideration of interaction between the aircraft and 
the engaging member and compatibility of aircraft with engaging member as judged from 
past experience. 

h. Cost and time of system design. 

i. Cost and time of development test program - relative time and cost 
advantages and disadvantages for each engaging system regardless of the type of test 
program conducted. 


B-4 



TR-1193 
Appendix B 


j. Cost of system installation. 

k. Cost of system operation and maintenance. 

l. Cost of prototype system procurement. 

m. Cost of production systems procurement. 

n. Compatibility with other aircraft - the potential of using the engaging system 
and energy absorber with other aircraft. 

NOTES: (1) All three engaging systems will impose 

approximately the same retarding load on the 
aircraft and will require approximately the 
same aircraft runout to dissipate the energy. 

(2) Exclusive of the engaging system/ all components 
of the recovery system, such as energy absorber, 
tape size, etc. , are identical regardless of which 
engagement mode is selected. i 

1.3.2 EMPHASIS CURVE 

a. Technique. Table 1 is a work sheet which illustrates the operation of 
the "Emphasis Curve" technique. 

(1) The parameters to be used in the comparison study are listed in 

any order. 

(2) Each parameter is then compared with every other parameter on a 
one for one basis. The evaluator must determine which of two parameters is the more 
important factor to be considered, when selecting an engagement mode. For example, 
if Engagement Reliability (E) is more important than Installation Cost (J), circle E on 
the work sheet where this comparison is indicated. 

(3) When every one of these individual comparisons is made, a 
summation is made of the number of times each parameter is circled. The parameter with 
the highest score is the most important, the lowest score indicates the least important. 
These values indicate the relative importance of each parameter - and are called Relative 
Importance Factors (RIF). 


B-5 



TR-1193 
Appendix B 


Table 1. Emphasis Curve Work Sheet 



WEIGHT PENALTY 


COST A/C MODIFICATIONS 


TECHNICAL RISK A/C MODIFICATIONS 


SAFE ARRESTMENT RELIABILITY 


ENGAGEMENT RELIABILITY 


NORMAL OPERATIONAL DAMAGE 


TECHNICAL RISK ENGAGING SYSTEM 


COST ANO TIME -DESIGN-ENGAGING SYSTEM 


COST AND TIME - DEVELOPMENT TEST 


COST- INSTALLATION 


COST OPERATIONS ANO MAINTENANCE 


PROCUREMENT COST PROTOTYPE 


PROCUREMENT COST - PRODUCTION 


®{A)©0®©0®@@@ 

SCOSFGHI ) K L 

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© ® © © 0 * © J * L 

C ©©©©©©©© 
® E F G H I j K L 

E * 8 H I t K l 

©©©©©©© 

f G H I J K L 

© ® © © © © 

B N I J K i 

© 6 © © © 

N © i * l 

« ® ® ® 

0 J K ,1 

© © © 

J R l 

i 1 
© © 
© 


© © 

M N 

© © 

M N 


' © 

© N 

R © 

® ■ 

l © 

® M 

® 

R 


COMPATIBILITY WITH OTHER AIRCRAFT 



B decisions analyzer form oa-i 

INDUSTRIAL EDUCATION INSTITUTE. BOSTON. MASS 


B-6 











TR-1193 
Appendix B 


b. Results of Emphasis Curve Analysis. 


Parameter RIF 

Weight Penalty 13 

Safe Arrestment reliability 12 

Technical risk - aircraft modifi- 
cation required 11 

Engagement reliabi lity 10 

Normal operational damage 9 

Cost and time - development test 
program 8 

Cost - aircraft modifications 

required 7 

Technical risk - engaging system 6 

Procurement cost - production 5 

Cost and time - design of engaging 
system 4 

Cost - operation and maintenance 3 

Procurement cost - prototype 2 

Cost - installation 1 

Compatibility with other aircraft 0 


c. Discussion. The analysis yields an excellent qualitative ranking of the 
importance of each parameter / and a rough quantitative ranking. Additional discussion 
on the importance of these parameters will be found in Paragraph 1.3. We assumed 
for the following Trade Off Study that the RIF's developed in the "Emphasis Curve" 
analysis permit a quantitative ranking of parameters. 



TR-1193 
Appendix B 


3. Scoring of Engaging Systems. Each engaging system is now assigned 
a score for each parameter. A high score indicates a system which satisfies the 
requirement of the parameter; a low score means the system does not satisfy the 
requirement. See Table 2. 



Maximum 


Good 


Average 


Poor 


Minimum 


1.3.4 ASSIGNING SCORES 
a. Weight Penalty. 

(1) The barricade was assigned the maximum score of 10 for this 
parameter since no aircraft modifications or additions would be necessary to be able 

to use this engaging device. Also, modifications which could be made to conventional 
aircraft to improve barricade compatibility, such as protrusions on the wing to retain and 
evenly distribute the loading straps, would seriously complicate the Space Shuttle design, 
to say the least. Hence, no additions to or modifications of the aircraft are needed or 
would be permitted for the barricade. 

(2) The landing gear entanglement system was assigned a very good 9 
since normal landing gear designs should provide sufficient strength to withstand the 
proposed arrestment loading, but small additions to the landing gear to help retain the 
barrier may be necessary. 


B-8 



TR-1193 
Appendix B 

(3) The hook-pendant system was scored a poor value of 3. A signifi- 
cant weight penalty will be incurred with this system due to the following additions to the 
Space Shuttle: 

(a) Hook. 

(b) Attachment structure, hook to aircraft. 

(c) Activating mechanism. 

(d) Heat shield for hook system, 
b. Safe Arrestment Reliability 

(1) A very good score of 9 was assigned to the hook system. The 
excellent safety record of this system has been adequately demonstrated with millions of 
trouble free arrestments of Navy, Marine and Air Force aircraft. Inexperience with 
engaging energies of the Space Shuttle magnitudes caused this score to be reduced from 
10 to 9. 


(2) The barricade was assigned a very poor value of 2. The many 
hazards associated with this type of engagement, such as retaining the net throughout 
the arrestment and poor off-center performance, have also been demonstrated by actual 
fleet experience. However, identification of these hazards has not yet led to the proper 
design techniques to eliminate or even reduce many of these problem areas. Barricade 
engagement of a high energy, swept and smooth surfaced wing vehicle would be extremely 
dangerous. 


(3) The landing gear entanglement system was assigned an average 
score of 6. Assuming a successful engagement, the system should be quite safe, 
but actual field experience with the design and the distant possibility of poor off-center 
performance with this system reduce reliability. 

c. Technical Risk - Aircraft Modifications Required. 

Cost - Aircraft Modifications Required. 

(1) Since no modifications or additions to the aircraft are required or 
permitted with the barricade system, we must assign the maximum score of 10 for these 
parameters. 

(2) Little or no modification of the aircraft is expected for the landing 
gear entanglement system; hence, the very good score of 9 was assigned. 


B-9 



TR-1193 
Appendix B 


(3) The additions to and modifications of the Space Shuttle, required 
for the hook-pendant system, are nearly identical to those required to equip conventional 
aircraft for this type of engagement. Sufficient experience has been gained to rate the 
reliability of operation of these components quite high. One area of unknown is the 
need to shield the hook from reentry heating and then remove this shield prior to 
activating the hook. Hence, an overall score of 7 (fairly good) was assigned for techni- 
cal risk and a poor score of 3 for cost. 

d. Engagement Reliability. 

(1) No problems are envisioned in designing a barricade net which 
would engage the aircraft with 100% reliability. Even a system which would be raised 
and positioned in a few seconds on a signal from the pilot should have very high reliability 
Hence, a score of 10 was assigned for the barricade. 

(2) The landing gear entanglement system historically has a very low 
engagement reliability. This problem has led to the discontinued use of this system by 
the military. A sensing and activating system is required to allow the forward landing 
gear to pass over the barrier and then engage both main landing gear. At the proposed 
engaging speeds and distance between landing gear, activation times of approximately 
1/8 of a second are required. Equipment which would stretch "state of the art" tech- 
nology in several disciplines would be required for such a system. This would result in 
low system reliability. Multiple systems would improve reliability by reducing the 
chance of a missed engagement caused by system malfunction, but they would not sub- 
stitute for inadequate system performance. Hence, the landing gear entanglement system 
was assigned the minimum value of 1 for engagement reliability. 

(3) Hook-pendant system engagement reliability of military aircraft 
with landbased recovery systems is quite high. Unlike the landing gear entanglement 
system, the pendant is an inactive member; it is merely held up off the deck a small 
amount to be engaged by the hook. There is no complex system operation to contribute 
to a reliability problem; hence, multiple pendants will significantly improve engagement 
reliability. The aircraft hook, however, must be activated. This operation is normally 
quite simple, but the Space Shuttle design may require a removable heat shield for the 
hook. Additional systems to insure hook activation should eliminate this problem. 

Hence, this system is assigned a very good score of 9. 

e. Normal Operational Damage. 

(1) The hook-pendant system is the operational mode of engagement 
for Naval aircraft on board aircraft carriers. A normal engagement and recovery with this 
system results in no damage to the aircraft. Hence, this systems rates a maximum 
score of 10 for this category. 


B-10 



TR-1193 
Appendix B 


(2) The barricade system is the emergency mode of engagement on 
board carriers. It is employed very infrequently and only when hook-pendant engage- 
ment is not possible, and if a shorebased landing cannot be made. A successful 
barricade arrestment is defined as one with little or no injury to the crew. Normal 
operational damage to the aircraft is accepted and is sometimes quite severe. Hence, 
this system is assigned a very poor score of 2. 

(3) Normal operational damage to the aircraft should be quite low with 
the landing gear entanglement system. However, off center engagement may cause 
some damage since the barrier would tend to slip relative to the landing gear struts. 

Also, experience with this system requires that we assign an average score of 5. 

f. Cost and Time - Development Test Program. 

(1) A test program of the barricade engagement system requires using 
an actual aircraft as the test vehicle. A simulated aircraft may be used which duplicates 
the aircraft's wings, tail, nose and landing gear, and has the same weight and center of 
gravity location. This vehicle is very costly. Normal operational damage and possible 
extensive damage caused by barricade systems, especially during these development 
tests, will require extensive repair of this vehicle after each test arrestment. This 
procedure will be very costly and time consuming. Hence, the barricade system rates 

a very poor 2 . 

(2) The landing gear entanglement system also requires use of a 
simulation vehicle, however, vehicle requirements are less stringent than those of the 
barricade test vehicle. Also, normal operational damage with this system should be 
much lower than that of the barricade system, with a subsequent reduction in cost and 
time. Hence, this system rates an average score of 5. 

(3) The test vehicle required for the hook-pendant system is a simple 
box shaped wheeled frame made of structural steel and weighted to the proper amount. 

The cost of this vehicle is also included in the barricade and landing gear entanglement 
test program time and cost estimates, since tests with this vehicle are necessary to 
develop proper recovery system operation prior to test with the actual engaging member 
and the simulated aircraft. Also, the hook-pendant engaging system permits testing of 
the recovery systems with the actual space shuttle vehicle at the installed operational 
sites. This could result in a cost and time saving for the test program and a final 
operational checkout of the installed systems. This type of final testing would not be 
permitted with the other modes of engagement due to the high probability of damage to 
the aircraft with these systems. Hence, the hook-pendant system is assigned an 
excellent score of 10. 


B-ll 



TR-1193 
Appendix B 


g. Technical Risk - Engaging System. 

(1) Experience indicates that the technical risk involved in designing 
a barricade system for any aircraft is quite high. The complications arising from smooth 
swept wings and very high kinetic energies significantly increase risk factors. Hence, 
this system was assigned a very poor rating of 2. 

(2) The previously mentioned "state of the art" technology required to 
design a sensing and activating system for the landing gear entanglement system imposes 
very high technical risks. Also, experience with this system requires the assignment of 
the minimum score of 1. 

(3) Technical risk involved in designing the hook-pendant system is 
quite low. Years of experience and the basic simplicity of the system minimize risk 
factors, inexperience with kinetic energies of the magnitude proposed for the Space 
Shuttle will impose a slight risk, reducing the score for this system to 9. 

h. Procurement Cost - Production. 

Procurement Cost - Prototype. 

(1) Procurement costs for the prototype or production models of the 
hook-pendant system are minimal. The proposed pendants are standard sizes, readily 
available. Hence, this system rates maximum scores of 10. 

(2) Procurement costs for the landing gear entanglement system are 
considerable. The sophisticated sensing and activating devices required would be 
very costly. Hence, a minimum rating of 1 was assigned for prototype procurement 
costs and a slightly better value of 2 for production costs. 

(3) Procurement costs for a specially designed barricade net, stanchion 
assembly, and sensing -activating device, if needed, would be large. However, these 
components should be simple compared to those contemplated for the landing gear entangle- 
ment system and the costs would be as significant for procurement of production systems 

as the prototype. Also, the nylon components deteriorate with time and would require 
periodic replacement with the operational system. The barricade system was, therefore, 

assigned a poor score of 3 for production procurement costs and a slightly better value of 
4 for the prototype. 

i. Cost and Time - Design of Engaging System. 

Design of a proper barricade net, stanchion and activating device 
will require a significant design effort. The net design may be critically dependent on 
the size, shape and strength of certain aircraft components. Delays in final design of 


B-12 



TR-1193 
Appendix B 


these components / or subsequent changes in them, may require significant redesign of 
the net. An average value of 5 has been assigned to barricade system design time 
and cost. 


(2) The sensing and activating system for the landing gear entanglement 
system will require a longer and more costly design program than that of the barricade. 
Delay or revision of the landing gear design may cause significant delay or revision of 
this engaging system. Limited experience will be a key design problem causing signifi- 
cant increases in time and cost. The landing gear entanglement system must be assigned 
a minimum score of 1 for Design Program Time and Cost. 

(3) No design problems are expected for the hook-pendant system. 

Like the barricade or landing gear entanglement systems, the pendant design is dependent 
on aircraft engaging speed and weight; but unlike these two systems, the pendant design 
is not dependent on aircraft shape, configuration, etc. Hence, delays or revisions of 
the aircraft design which cause little or no change in engaging kinetic energy will not 
complicate the design program of the hook-pendant system. This system is, therefore, 
assigned the maximum score of 10 for Design Program Time and Cost. 

j. Cost - Operation and Maintenance. i 

Cost - Installation. 

(1) The simplicity of the hook-pendant system, and the relatively low 
cost for replacing components, minimize installation, operation and maintenance costs. 
These parameters are assigned the maximum score of 10 for the hook-pendant system. 

(2) Installation costs are maximum with the barricade system and 
landing gear entanglement system. The components needing replacement after operations 
are costly, and the systems required for sensing and activation require constant attention. 
Both systems are rated the poor value of 3 for these costs. 

k. Compatibility with Other Aircraft. No scores need be assigned for this 
parameter since it was given a RIF of zero. 

1.4 RESULTS 


a. Table 2 summarizes the trade-off study. It shows: 

(1) A list of parameters used in the trade-off study and the relative importance 
factors of each. 

(2) The scores assigned to each engaging system for each parameter. 


B-13 



TR-1193 
Appendix B 

Table 2. Engagement Mode Trade-Off Study 




BARRICADE 

HOOK- 

PENDANT 

LANDING GEAR 
ENTANGLEMENT 

PARAMETER 

RIF 

SCORE 

RIF x SCORE 

SCORE 

RIF x SCORE 

SCORE 


Weight Penalty 

13 

10 

130 

3 

39 

9 

117 

Safe Arrestment Reliability 

12 

2 

24 

9 

108 

6 

72 

Technical Risk - Aircraft 
Modifications 

11 

10 

110 

7 

77 

‘ 

9 

99 

Engagement Reliability 

10 

10 

100 

9 

90 

1 

10 

Normal Operational 
Damage 

9 

2 

13 

10 

90 

5 

45 

CostA'lme - Development 
Teat 

3 

2 

1« 

10 

30 

5 

40 . 

Cost - Aircraft Modifica- 
tions 

■ 

10 

70 

3 

21 

9 

S3 

Technical Risk - Engaging 
Device 

fl 

2 

12 

9 

54 

1 

i 6 

1 

Procurement Cost - 
Production 

B 

3 

13 

10 

50 

2 

10 

Cost/Time - Design - 
Engaging System 

B 

5 

20 

10 

40 

2 

8 

Cost - Operation and 
Maintenance 

3 

3 

9 

10 

30 

3 

9 

Procurement Cost - 
Prototype 

2 

4 

8 

10 

20 

1 

2 

Cost - Installation 

1 

3 

3 

10 

10 

3 

3 

Total 

910 


833 


709 


484 

r « Total/Max Possible 



.59 


.78 


.53 


B-14 

























TR-1193 

Appendix B 


(3) The effective scores of each system for each parameter, obtained by 

multiplying the proper score and RIF. 

(4) Total effective score of each system; and ratio of this total to the 
maximum possible score. 

b. This study shows that the optimum mode of engagement is the hook-pendant 

system. 

- Wral Qualified evaluators used this technique and arrived at the same 

. c ' . that in- hook-pendant system was optimum. Only minor differences 
conclusion; i.e. , that the hoc _ P y d when the various analyses 

rerTc^rlh 0 ; «Ls“din this report are in agreement with all the 

evaluations. 

d. Importance of Parameters. 

n ^ Safe Arrestment Reliability. A Relative Importance Factor of 12 was 

d rn this Darameter by the "Emphasis Curve" analysis. If Weight Penalty was 
assigned to this parameter Dy ine h m was the prim ary system to arrest 

the aircraft Thifparameter would be the only one considered in evaluating engagement 
mode Thk would result in selection of the hook-pendant engagement mode. 

(?) Weioht Penalty. The previous analysis assumes that a Weight Penalty 

zssagssss&saKa 

engagement mode. 


B-15/16 



03 vj O' U1 J^W MH 


TR-1193 


APPENDIX C 

RECOVERY SYSTEM DESIGN AND DESCRIPTION 


TABLE OF CONTENTS 


Paragraph Title P a 9 e 


1.0 INTRODUCTION C-3 

1.1 ARRESTING GEAR DESCRIPTION .... C-3 

1.2 ENGAGEMENT MODES C-5 

1.3 TIME AND COST ESTIMATES C-5 

1.4 ALTERNATE LANDING SITES C-12 


LIST OF ILLUSTRATIONS 


Figure Title P a 9 e 


Space Shuttle, Arresting Engine C-4 

Recovery System, Hook Engagement C-6 

Proposed Barricade, Space Shuttle Orbiter . C-7 

Orbiter Engagement C-8 

Barricade, Quick Erect C-9 

Barricade, Slow Erect C-10 

Landing Gear Entanglement Recovery System C-ll 

Mobile Arresting System C-13 


C-l/2 



TR-1193 


APPENDIX C 

RECOVERY SYSTEM DESIGN AND DESCRIPTION 


1.0 INTRODUCTION 

a. This study presents drawings and descriptions of the proposed recovery sys- 
tem's major components. These conceptual designs were used to prepare time and cost 
estimates for design and manufacture of both the prototype and production systems. A 
preliminary cost effectiveness trade off study for equipping alternate operating sites with 
recovery systems is also included. 

b. The recovery system is composed of the main components designed in 
Appendix A, one of the engaging systems discussed in Appendix B and other necessary 
support equipment. In the following descriptions, all recovery system components ex- 
cept the engaging member are included in the arresting gear discussion. 

1.1 ARRESTING GEAR DESCRIPTION (Figure 1.) 

a. The arresting gear utilized in the space shuttle recovery system is the 
same, regardless of the mode of vehicle engagement. This arresting gear consists of 
two arresting engines installed on a concrete pad, one on each side of the runway. 

Each engine is equipped with a nylon purchase tape which is stored on a reel, reeved 
through a deflector sheave and coupled to the vehicle engaging device. 

b. The major components of the arresting engine are the energy absorber, the 
retrieve system, the tape support flanges, a tape pressure roller system and a deflector 
sheave. All are mounted on a single steel base plate. 

c. The tape hub and energy absorber rotor are splined to the main shaft. The 
tape hub and rotor function as a unit. Pullout of the tape drives the hub and rotor, whose 
motion is resisted by the fluid in the housing. 

d. The electrically powered retrieve system is used to wind the tapes onto 
the reels and pretension the engaging device in preparation for arrestment. The system 
is automatically disengaged from the tape hub at the time of vehicle engagement by a 
pretension release mechanism. Thus, the tape hub and rotor are allowed to run free of 
the retrieve system during arrestment. 

e. The tape pressure roller system ensures an even, tight wrapping of tape on 
the hub during retrieve. It consists of a roller mounted on an arm which is pivoted in a 
bracket secured to the arresting engine base. The arm is tensioned by a spring and 
winch assembly. 


C-3 



TAPE PRESSURE ROLLER SYSTEM 


TR-1193 
Appendix C 



C-4 


Figure 1. Space Shuttle, Arresting Engine 





TR-1193 
Appendix C 


1.2 ENGAGEMENT MODES 


a. The pendant system consists of a pendant or rope stretched across the run- 
way and elevated at set intervals by pendant supports (Figure 2). The pendant is 
attached to the purchase tape by a tape connector. During arrestment, it is engaged by 
a hook mounted on the vehicle. 

b. The second method of engagement is by the use of a barricade, a large 
nylon net (Figure 3). The barricade is stretched across the runway and when engaged, 
deploys itself over the wings of the vehicle (Figure 4). It is attached to the purchase 
tape by means of nylon straps. 

(1) The barricade is raised and supported by stanchions. The means em- 
ployed in raising the stanchions is dependent upon the desired erection time. A quick 
erect system (2 to 3 seconds) would be required in an abort situation which could be 
encountered during flight tests. A slow erect system (20 to 30 seconds) would be 
suitable for any operational situation where the barricade can be pre-rigged as a 
precautionary measure prior to landing. 

(2) The quick erect system (Figure 5) uses rack and pinion type rotary 
actuators to raise the stanchions. The actuators are powered by a hydraulic power pack 
which utilizes accumulators, a series of distribution and flow control valves and an 
automatic recharge system. The entire system is activated by an electrical control 
signal. 


(3) The slow erect system (Figure 6) uses an electrically powered winch 
to raise the stanchions. Control is exercised at the barricade site. 

c. The landing gear entanglement system (Figure 7) uses a nylon net connected 
to the purchase tapes, to ensnare the main landing gear of the vehicle. A detection 
device is used to continuously compute the distance between the oncoming vehicle and 
the arresting gear. At the proper instant the device sends a signal to the net pop-up 
system, which throws the net up into the path of the main landing gear. Timing of the 
net actuation is critical because the net must remain in a retracted or recessed position 
until the nose gear has passed over it. Ensnaring the nose gear would result in failure 
of the strut and/or severe aircraft swerve during the arrestment due to concentration and 
location of the retarding load forward of the aircraft center of gravity. A similar problem 
exists if only one main gear is engaged by the net. With the desired engaging speeds 
and current estimates of vehicle landing gear configuration, the time available for com- 
plete and accurate net deployment is approximately 1/8 second. 

1.3 TIME AND COST ESTIMATES 


Design and manufacture of the prototype system and manufacture of production 
systems' time and cost estimates are presented in Appendix E. 


C-5 




Figure 2. Recovery System, Hook Engagement 


C-6 




TR-1193 
Appendix C 






s 


Figure 6. Barricade, Slow Erect 



TR-1193 
Appendix C 



Figure 7. Landing Gear Entanglement Recovery System 


C-] 


TR-1193 
Appendix C 


1 .4 ALTERNATE LANDING SITES 

a. Permanent installations of recovery systems are planned for primary landing 
sites; however, in the event that a primary site becomes unavailable for operation, 
suitable alternate recovery sites are planned. For these sites, recovery system in- 
stallations can be one of three types: mobile, semi-mobile or permanent. 

b. Mobile or expeditionary installations (Figure 8), similar to the Marine Corps 
M-21 system, are currently used with a high degree of success. However, because of 
the size and loading requirements of the proposed system, it is estimated that installation 
would require a minimum of three days after delivery of the equipment to the site. For 
barricade or landing gear entanglement systems, this time would be significantly greater. 
This delay in availability of the system is considered to be unacceptable. 

c. The semi -mobile system is mobile in that it can be transported to and 
mounted at any alternate site. However, each alternate site would have permanent 
foundations and facilities already installed. 

The advantages are as follows: 

(1) One recovery system can be used for several sites, thus reducing pro- 
curement costs. 

(2) The system can be made available for arrestment within 24 hours after 
delivery of equipment to the site. 

The disadvantages are as follows: 

(3) Foundation and facility costs are as high as with permanent type 

installation. 

(4) Handling equipment is required for each system. 

(5) Repeated transportation and installation costs are encountered. 

(6) Manpower requirements are increased. 

d. A permanent recovery system, of course, has no mobility; however, it 
has one major advantage which weighs heavily in its favor. The system is always 
available for immediate use. There is no lead time required for transportation and 

installation. The major disadvantage is that a complete system must be procured for 
each location. 


C-12 



TR-1193 
Appendix C 



Figure 8. Mobile Arresting System 


C-13 


TR-1193 
Appendix C 


e. A cost effectiveness study of the permanent and semi -mobile installations 
was undertaken by considering costs such as procurement (number of systems), 
installation, transportation and special handling equipment. It soon became appar- 
ent that the cost advantage varies with the type of system selected (pendant, barricade 
or landing gear entanglement) and the number of alternate sites to be considered 
Therefore, quantitative results of this study are not pertinent until these variables are 
fixed. The study can be resumed at any point in time during the development program 


f. Based on preliminary estimates and 
tages, the following are recommended: 


considering operational and cost advan- 


(1) Pendant system for three or less alternate runways, two systems oer 

runway - permanent installations. M 

(2) Pendant system for more than three alternate runways, two systems per 

runway - semi -mobile installations. y Mer 


(3) Barricade or landing gear entanglement systems for two or more alternate 
runways, two systems per runway - semi -mobile installations. 

g. It should be noted that since both of the recommended types of installation 
require the same site preparation and foundation, a delay in the selection of the desired 
type will not affect design or development of the arresting gear system. 

i i 1 * u ,f t b L. y fut uM assessment of operational requirements, the delay in availability 
involved with the mobile system is considered acceptable, additional time and cost will 
be incurred for design and manufacture of the installation hardware. 


C-14 



TR-1193 

APPENDIX D 
TEST PROGRAMS 

TABLE OF CONTENTS 

Paragraph Title Page 

1.0 INTRODUCTION D-3 

1.1 TEST FACILITIES D-3 

1.2 TEST PROGRAMS D-4 

1.2.1 STANDARD D-4 

1.2.2 NON-STANDARD D-5 

1.3 SUMMARY OF TEST PROGRAMS AND FACILITIES COST .. . D-9 

LIST OF ILLUSTRATIONS 

Figure Title Page 

1 Deadload Assembly, 275,000 Lbs. Max. Wt. D-6 

2 Proposed Space Shuttle Deadload D-7 

3 Proposed Jet Pusher Car, Space Shuttle Deadload D-8 

LIST OF TABLES 

Table Title Page 

1 Test Program Summary D-10 


D-l/2 



TR-1193 


APPENDIX D 
TEST PROGRAMS 


1.0 INTRODUCTION 

Time and cost estimates are presented to test the recovery system. Test program 
cost factors are dependent on the engagement mode chosen and the maximum kinetic 
energy to be tested. Hence, several estimates are provided. Descriptions of test pro- 
cedures and test site facilities required are also presented. 

1.1 TEST FACILITIES 


a. Tests of the recovery system are conducted by instrumenting and recording 
the response of the system to the engagement of an unmanned test vehicle. The weight 
and engaging speed of the test vehicle are adjusted to simulate actual operating conditions. 
Modifications of the recovery systems are conducted, if necessary, to produce proper 
system operation. 

b. The kinetic energy of the test vehicle is developed by pushing it down a 
long track with a jet car. The jet car is a vehicle on which jet engines are mounted for 
propulsion. Both the jet car and test vehicles are guided down the track by steel Ibeam 
rails imbedded in the concrete track. At a fixed point on the track, the jet car is 
stopped and the test vehicle continues on to be engaged by the recovery system. The 
length of track over which the test vehicle is accelerated by the jet car is constant. 

The jet engine thrust is varied to produce various engaging kinetic energies. 

c. As the test vehicle separates from the jet car and engages the recovery 
system, it is freed from the guide rails. 

d. In addition to duplicating the kinetic energy of the actual aircraft, the 

test vehicle must simulate various aircraft components depending on the mode of engage- 
ment chosen for the recovery system. 

(1) For hook-pendant mode of engagement, the test vehicle can be a 
simple box -shaped, wheeled vehicle ("deadload" vehicle) made of structural steel 
with a hood attached. The hook need not be the same length as the one designed for 
the aircraft, but the hook point should be the same (e.g. not critical). 

(2) For barricade mode of engagement, the test vehicle must closely re- 
semble the actual aircraft. The vehicle must duplicate the aircraft's wings, tail, 
nose, undercarriage, landing gear and center of gravity location. 


D-3 



TR-1193 
Appendix D 


(3) For landing gear entanglement mode of engagement, the test vehicle 
must duplicate the aircraft's undercarriage, landing gear and center of gravity location. 

e. Steps d(2) and d(3) require the test vehicle to duplicate the landing gear 
and undercarriage of the aircraft. During the power stroke with the jet car, these 
vehicles must use the rails for guidance. To accomplish these two requirements a 
shuttle frame vehicle is employed. The shuttle frame vehicle is pushed ahead of the 
jet car and is guided by the rails. The test vehicle is mounted on top of the shuttle 
frame. When the jet car is brought to a stop at the end of the power stroke, the shuttle 
frame also stops, and only the test vehicle continues on to be arrested. 

f. The initial stage of the test program is used to check out and adjust the 
operation of the arresting engines. This phase is conducted with hood-pendant mode 
of engagement and the simple "deadload" test vehicle regardless of the engaging mode 
chosen for the actual system. 

g. Subsequent stages of the test program are used to determine compatibility 
of the aircraft and the selected engaging member, and total system performance. 

h. Summary of Main Test Facilities Required. 

(1) Test Vehicle - Deadload 

(a) Required to test hook/pendant engagement mode 

(b) Required to test arresting engines for any engagement mode 

(2) Test Vehicle - Simulated aircraft required to test barricade or landinq 

gear engagement modes y 

(3) Jet Car - Propels test vehicle 

(4) Shuttle Frame Vehicle - Guides simulated aircraft test vehicle. 

(5) Jet Car Track - Jet car power stroke track 

(6) Support Services - Instrumentation equipment and trained personnel 
1.2 TEST PROGRAMS 

1.2.1 STANDARD 


a. 

under expected 


Recovery systems designed for U.S. Navy aircraft are always tested 
operational conditions. The test program attempts to duplicate the total 


D-4 



TR-1193 
Appendix D 


environment under which these systems will operate. This obviously includes testing 
all possible combinations of aircraft weights and speeds which may be encountered. 

This procedure is the only way to develop a safe, reliable system. 

b. Therefore, it is strongly recommended that a standard test program, 
which would include all possible aircraft weight and speed combinations expected for 
the NASA Space Shuttle, be conducted. 

c. In order to conduct the standard test program a major upgrading of the 
current test facilities is required. This would include new test vehicles, new jet car 
and shuttle frame (if required), extension of the jet car track and recovery area and 
additional support services. The cost of these facilities is $8.5 to $9.4 million, 
depending on the engagement mode selected. This would provide a kinetic energy 
capacity of 590 x 10° ft-lb or 275,000 lb at a speed of 220 knots. Preliminary 
design layouts of the deadload, simulated aircraft, and jet car are shown in Figures 1 
thru 3, respectively. 

1.2.2 NON-STANDARD 

a. Preliminary cost estimates to provide test facilities for the standard 
test program, presented at the Mid-Program Review of this study, were of necessity 
quite large. At the request of attending NASA representatives, several other test 
programs were investigated. These programs attempt to minimize facilities improve- 
ment costs by eliminating the design and manufacture of the new high-energy jet car 
(estimated cost $5.5 million). Two of the programs are based on using existing jet 
car track facilities at the Naval Air Test Facility, Lakehurst, N.J. 

b. Existing Facilities Test Program. 

(1) The maximum engaging energy conditions capable of being tested 
with existing jet car and track are considerably less than the maximum energy condition 
used as design criteria for this recovery system. Extrapolation of hook-pendant 
performance data from these low test energies to desired operating energies involves a 
very high technical risk which could result in inadequate performance when the system 
is most needed. Extrapolation of test data for barricade or landing gear entanglement 
engagements is, from past experience, virtually impossible. Hence, the reliability 
and safety of the recovery system at the higher engaging energies would be almost 
impossible to predict. 

(2) This program requires new test vehicles and extension of the runout 
area for a facilities cost of $1.7 to $2.6 million, depending on engagement mode 
selected. The maximum kinetic energy capacity is 145 x 10^ ft-lb. 


D-5 



TR-1193 
Appendix D 



D-6 


Figure 1. Dead Load Assembly, 275,000 Lbs. Max. Wt. 


TR-1193 
Appendix D 



TR-1193 
Appendix D 



TR-1193 
Appendix D 


c. Existing Facilities with Rocket Assist Program. 

In order to more closely approach the desired test energies without the cost 
of the new jet car, use of rockets to augment the existing jet car thrust was investigated. 
By use of 30 ,000 lb thrust rockets with a 60 -second bum time, engaging energies up 
to 277 x 10° ft -lb can be obtained. This reduces significantly the amount of data 
extrapolation required and reduces the technical risk involved. The cost of this program 
is only slightly higher than the previous one, excluding cost of the rockets. It is 
anticipated that these rockets will be provided by NASA, however, their availability 
has not been determined to date. 

d. Existing Jet Car With Extended Track Program. 

Another method of providing increased energy capacity, approximately the 
same as the rocket assist program, is by extending the jet car track to provide a longer 
power stroke for the existing jet car. While offering the same advantages as the rocket 
assist program, the facilities improvement costs for this program are higher (again, 
excluding rocket cost). This cost would be $3.0 to $4.0 million, depending on engage- 
ment mode selected. 

1.3 SUMMARY OF TEST PROGRAMS AND FACILITIES COST 

Table 1 contains a summary of the various test programs for the three engaging 
modes, the related facilities improvement costs and the maximum engaging energies 
and conditions attainable. The costs of conducting the test programs are included in 
Appendix E. 


D-9 


Table 1. Test Programs Summary 



FACILITIES IMPROVEMENT COST pi^s ° ^ FiiT Phis $3,040 K $3,916 K $3,660 K 


































































TR-1193 

APPENDIX E 
COST SCHEDULES 

TABLE OF CONTENTS 

Paragraph Title Page 


1.0 DEVELOPMENT PROGRAM COSTS E-3 

1.1 PROGRAM SYSTEM COSTS E-3 

1.2 TOTAL PROGRAM COST E-3 


LIST OF TABLES 

Table Title Page 


1 Pendant System Test/ Site Capability E-4 

2 Pendant System Test, Jet Car/Rocket Assist E-5 

3 Pendant System Test, Jet Car/Extended Track . E-6 

4 Barricade System Test, Site Capability E-7 

5 Barricade System Test/ Jet Car/Rocket Assist E-8 

6 Barricade System Test, Jet Car/Extended Track E-9 

7 Gear Entanglement System Test/ Site Capability E-10 

8 Gear Entanglement System Test, Jet Car/Rocket Assist E-ll 

9 Gear Entanglement System Test, Jet Car/Extended Track E-12 

10 Hook-Pendant System E-13 

11 Barricade System, Slow Erect E-14 

12 Barricade System, Rapid Erect E-15 

13 Gear Entanglement System E-16 


E-l/2 



TR-1193 


APPENDIX E 
COST SCHEDULES 

1.0 DEVELOPMENT PROGRAM COSTS 

Summaries of overall program time and cost estimates / exclusive of production 
systems to be installed on NASA sites, are presented in Tables 1 thru 9. The costs 
include design and manufacture of the prototype arresting system, test facilities im- 
provement costs and test program costs. Due to the results of the aforementioned Mid- 
Program Review, detailed cost estimates for the standard Navy type test program (full 
rated energy) have not been included. Estimates are provided for the three engagement 
modes and three test methods for each. The number of test engagements recommended 
for each program has been carefully selected to produce the greatest amount of useful 
information for the least possible cost, within the energy capability of the test method. 
Consideration was also given to the relatively short time available until the tentative 
required delivery date of the initial recovery system. Time estimates given are in years 
from initiation of the program. 

1.1 PRODUCTION SYSTEM COSTS 

Cost estimates for production models of the pendant, slow erect barricade, fast 
erect barricade and landing gear entanglement systems are presented in Tables 10 thru 
13 respectively. Again, time estimates are given in years from initiation of the program. 
Note that costs include the complete recovery system, site preparation and system in- 
stallation and spare components. 

1.2 TOTAL PROGRAM COST (Determination) 

Determination of total program cost first involves selection of an engagement mode 
and a test method to establish development program costs. Subsequently, the number of 
production systems to be procured must be established to determine landing site provision- 
ing costs. This involves the number of landing sites and the number of systems to be 
installed per runway. When considering the number of systems to install per runway, the 
reliability of the engaging system is of prime importance. 

a. Hook-pendant system engagement reliability is good and can be improved by 
use of multiple pendants. Therefore, two systems per runway, one at each end, each 
system having two pendants attached (dual pendant system), are recommended. 

b. Engagement into the barricade webbing has a high degree of reliability. Two 
systems per runway, one at each end, are recommended. 

c. Landing gear entanglement system engagement reliability is very low, but 
can be improved somewhat by use of multiple engaging devices. However, spacing 
required between the primary engaging member and the backup engaging member pre- 
cludes attaching both to the same energy absorber. Therefore, the only means of in- 
creasing engagement reliability appears to be by use of four systems per runway, two 
at each end. 


E-3 



TR-1193 
Appendix E 



E-4 



















Table 2. Pendant System Test, Jet Car/Rocket Assist 















Table 3. Pendant System Test/ Jet Car/Extended Track 


TR-1193 
Appendix E 





























































Table 6. Barricade System Test/ Jet Car/Extended Track 


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TR-1193 
Appendix E 



E-10 
























Table 8. Gear Entanglement System Test, Jet Car/Rocket Assist 


TR-1193 
Appendix E 



E-ll 



























Table 9. Gear Entanglement System Test/ Jet Car/Extended Track 


TR-1193 
Appendix E 


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E-12 





* Not Re earring Costs 
** Includes Two Tapes and One Pendant 
















E-14 


Not Recurring Costs 

Includes Two Tapes and One Barricade 
















** In clod es Two Tapes and One Barricade 




















Table 13. Gear Entanglement System 



r o Tapes and One Engaging Member