1. Trade Study Methods

2. Types of Trade Studies
Controlled Convergence - Preliminary Method Used by Engineering. Quick Method to Compare “Primitive” Design Variables
Cost Effectiveness - Links Force Structure Implications to Top Level Requirements Analysis
Comprehensive - Considers all Applicable Decision Criteria

3. Time Frames For Trade Study Methods
--Comprehensive--
------Cost-Effectiveness
-Controlled Convergence-
Production & Deployment
Pre Concept & Tech Dev A B C
Concept & Technology Development
System Development & Demonstration
Operations & Support

4. Controlled Convergence Trade Study

5. Steps in Applying Controlled Convergence Method
1. Design Alternatives to Same Level of Detail
2. Choose Comparison Criteria
3. Choose a Baseline for Comparison Purposes
4. Compare the Alternatives to the Baseline
5. Sum Pluses and Minuses
6. Can New Alternative Be Created by Changing Negative(s) of a Strong Alternative?
7. Can Weak Alternative Be Eliminated?
8. Return to Step 4 or Document Findings and Proceed

6. Controlled Convergence Method For Preliminary Trade Studies
Design
Alternatives 1 2 3 4 5
Comparison
Criteria
(Baseline)
(Design Primatives)
Thrust/Weight (T/W) S – S – +
Weight/Wing Ref. Area (W/S) S – – + +
Coef. of Lift (C ) S – + – L –
Cruise Performance (Specific fuel S S + S +
consumption, range, speed)
Observables (Shaping, materials, S S + S –
propulsion, etc.)
Payload Capacity S – + – S
Agility (maneuverability & S + + – +
controllability)
...
TOTAL +'s 1 5 2 4
TOTAL S's 7 2 1 1 1
TOTAL –'s 4 1 4 2
+ Significantly Better
Legend
S About the Same
– Significantly Worse

7. Strengths and Weaknesses of Controlled Convergence Preliminary Trade Study Method
Difficult for Strong-Willed Person to Dominate Decision Making
Encourages Development of Additional Design Alternatives
Time to Converge Can Be Controlled
Repeated Applications of This Method Will Result in “Fuzzy” Comparisons of Leading Alternatives

8. Cost-Effectiveness Trade Study

9. Alternative Configuration Scoring Methods

12. Life Cycle Cost Composition
WEAPON SYSTEM COST
• Tech Data
• Publication
• Contractor Service
• Support Equipment
• Training Equipment
• Factory Training
• Management
• Hardware
• Software
• Nonrecurring "Start-up"
• Allowance for Changes
FLYAWAY COST
PLUS
• Initial
Spares
• RDT&E
• Facility
Construction
• Operations &
Support
(Includes
Post-Produc-
tion Support)
• Disposal
PROCUREMENT COST
PROGRAM ACQUISITION COST
LIFE CYCLE COST
BV41861

13. Cost Estimating Methods Used During Acquisition Phases
P = Primary
S = Secondary
Pre Concept & Tech. Dev.
Concept & Tech. Dev.
Early in System Dev. & Demonstration
Early in System Dev. & Demonstration
Prod. & Dep.
Parametric
Analogy
Bottom-
Up Eng. P S S
N/A
N/A S P S
N/A
N/A
N/A S P P P

14. Relative Values of LCC Elements (based on 100 aircraft)
Life Cycle Cost
Operations & Support
(46.1%)
RTD&E (4.3%)
Procurement (49.6%)
0.30 Demo/Validation
2.12 Air Vehicle
0.13 Engine
0.22 Offensive Avionics
0.70 Launcher
0.02 Training
0.06 Special Support Eqpt
0.47 Test & Evaluation
0.15 Project Management
0.13 Data
0.59 Tooling & Engineering Airframe
8.83 Engine
2.31 Offensive Avionics
2.18 Launcher
0.17 Training
1.94 Special Support Eqpt
0.36 Test & Evaluation
0.07 Project Management
0.15 Data
1.52 Initial Spares
1.74 Replenish Sppt Eqpt
Fuel
0.92 Base Level Maint.
Depot Maint.
3.70 Updating/Mods
0.78 Replenish Spares
0.06 Vehicular Eqpt
Military Personnel
Civilian Personnel
1.29 Support Personnel
2.23 Pipeline Costs

15. Comprehensive Trade Study

16. Principal Steps in Comprehensive Trade Study
1. Identify Decision Criteria within Broad Decision Categories
2. Quantify Decision Criteria for Each Configuration
3. Analyze Customer Preferences for Each Decision Criterion
4. Assign Weights to Decision Criteria
5. Score Each Configuration (Sum Weights x Preferences)
6. Perform Sensitivity Analysis on Weights If Configuration Scoring Is Close

20. Sample Configuration Decision Categories
Air Vehicle
Effectiveness
Cost
Risk
Threat Acquisition
Avoidance
Hit Avoidable
Given Acquisition
Sortie Survival
Given Hit
Target Acquisition
Target Kill
Kills per Sortie
Targets Killed
Over Time
Flyaway
Weapon System
Procurement
Program Acquisition
Life Cycle
Technical
Cost
Schedule
Producibility
Supportability
Management

21. Utility Functions - Preference Indicators
Utility Functions Provide a Good Technique for Translating Diverse Criteria Into a Common Scale. (i.e., Range in NMi, MTBF in Hours, etc.)
Utility Scores Range From 0 to 1 With 0 Being Least Preferred and 1 Being Most Preferred.
Examples
Utility for Range
Utility for MTBF 1 1
Threshold Objective
Threshold Objective
Range in MNi
MTBF in hours

22. Hints for Determining the Shape of Utility Functions1 1
After Establishing the
Minimum Requirements
and Goal, Draw Neutral
Preference Position as
Shown Neutral
Preference
Critical,
Risk Prone
Non-Critical,
Risk Average
Req Decision Factor Goal 1 2
Divide Decision Factor
into Quartiles and
Assess 25%, 50%, and
75% Points Relative to
Neutral Preference
Req Decision Factor Goal

23. Sensitivity Analysis of Configuration Preferences
Select Factor of Interest Such as Performance Range
Increase Weight for Factor of Interest Until the Preferred Alternative / Configuration Changes
Incrementally Lower the Weight for Factor of Interest Until the Preferred Alternative / Configuration Changes

24. Exercise
Background: As system requirements are identified and flowed down form the SDR, design options for the Group A hardware must be identified and trade studies performed to determine the best design. Five design options have been developed for Group A and have been evaluated by the AFS design team. Documentation of this first pass design review by the team is presented below and must now be used to select the best design in support of entrance criteria for the program PDR.
Exercise: In order to limit the scope of this Exercise, the design trade study will be restricted to the Aft Antenna and Radome assembly. Referring to the Introductory Briefing material presented on the four subsequent charts, the Statement of Customer Requirements Part 2, and the Aft Antenna/Radome Functional Requirements Baseline, evaluate the designs provided and perform a comprehensive trade study to select the best design.

25. AJS Statement of Customer Requirements
Customer: Kurdish Fighter Program (Peace Whey)
Operational Need: Fighter aircraft operating in a hostile environment require extensive electronic countermeasures (ECM) to defeat air-launched and ground-launched threats to the survivability of the aircraft. These ECM systems must be capable of generating and broadcasting radio frequency (RF) energy at sufficient power levels and in appropriate patterns to defeat any threat encountered by the aircraft.

26. AJS Statement of Customer Requirements (Cont.)
Description: The AJS shall be capable of installation on a lightweight, high-speed, multi-role fighter and shall be supportable in primitive forward operating bases. The system shall be capable of transmitting radio frequency signal in the microwave frequency range at sufficient power levels and in patterns capable of successfully jamming all identified threats at the required operational range. The AJS system shall consist of the following major components:
1. Core Avionics: Shall consist of the jammer, the radar warning receiver, and the OFP software. Shall be capable of generating the required RF signal in the microwave band at required power levels and of detecting radar emissions from the threat set at the required ranges.
2. RF Switch H/I/J Band: Shall control selection of broadcast frequency bands as required.
3. Fire Control Radar Notch Filter: Shall prevent interference of the Fire Control Radar (FCR) by the AJS system.
4. Forward Transmit Antenna
5. Aft Transmit Antenna and Raydome
6. WRD-650D24 Waveguide
7. Coaxial Cable

27. AJS Statement of Customer Requirements (Cont.)
Schedule:
1. Flight Test: The Safety of Flight(SOF) unit for flight test shall be available for installation 26 months after program go-ahead.
2. First Production Delivery: The first production assembly shall be delivered 36 months after program go-ahead.
3. Delivery Rate: Delivery of AJS units shall be at the rate of 2 units per month.
4. Total Quantity: The total quantity of AJS units shall be 20.
Customer Priorities:
1. Power Transmitted.
2. Weight
3. First production delivery.
4. Cost not to exceed $125,000/unit (for 20 units).

30. Types of Radomes Types of Construction Uses and Advantages
Solid-Wall Construction Laminated Glass Cloth/Resin or Filament Wound
Sandwich-Wall Construction Laminated Glass Cloth/Resin Impregnated Skin with Various Dielectric Cores
Narrow Frequency Band
High Strength
Optimized Electrical Performance
Broad Frequency Bandwith
Lightweight

31. Extensive Testing of Antennas Confirms That Performance Will Be Achieved
Parameters Tested:
- Electrical Requirements: Antenna Range
1. Radiation Patterns and Gain
2. Voltage Standing Wave Ratio (VSWR)
3. RF Power Handling
4. Antenna-to-Antenna Isolation
- Environmental Requirements: Engineering Test Labs
1. Vibration
2. Temperature - Altitude
3. Humidity
4. Acoustical Noise
5. Mechanical Shock

32. Airborne Jamming System (AJS) Statement of Customer Reqt.’s: Part 2
Performance:
1. Frequency: The AJS shall provide performance over the frequency ranges and angular pattern as represented in Table 1. The low-band transmission line shall be coaxial cable. The high-band transmission line shall be double-ridge, pressurized Waveguide of type WRD-650D24.
2. RF Power Handling: The AJS, while operating in any combination of temperature and pressure consistent with the aircraft operating envelope (as shown in Figure 1), shall be capable of handling 1500 watts peak power in a continuous transmit mode.
3. Antenna Polarization: The transmit antennas shall be left-hand circularly polarized.
4. Antenna Gain: The gain for each antenna shall be as specified in Table 1 and Figure 2. The gain is defined as gain measured at the minimum level of the axial ratio and is referenced to isotropic linear polarization.

33. Airborne Jamming System (AJS) Statement of Customer Reqt.’s: Part 2
Environmental:
1. The AJS total system shall be capable of operation at all points in the aircraft flight envelope as specified in Figure 1.
2. The antenna/radome assembly shall have a mean time between failures (MTBF) of greater than 50,000 hours.

42. Exercise # 4 Option 1 Risk Issues
Risk Issues: Very good chance additional heat sink capacity will be needed to sustain power rating. This creates .4 pound of weight risk. Schedule risk is assessed as low.

45. Exercise # 4 Option 2 Risk Issues
Risk Issues: Low system weight achieved through use of spiral antenna impacts power handling capability and gain. Design of antenna mounting hardware results in predicted failure of vibration and acoustic loading spec due to resonant response within frequency envelope. Structural design changes required to meet vibration and acoustic specs result in a highly likely probability that the total assembly weight will add 1 pound of weight, exceeding spec. There is also a better than even chance that two additional calendar months design/development time will impact delivery of SOF hardware.

48. Exercise # 4 Option 3 Risk Issues
Risk Issues: Slightly higher-than-spec gain in the high band is due to an improved dielectric currently under development. The risk of additional development and testing costs resulting in a assessment of a probable AJS system cost increase per unit of +3%. There is an unlikely probability the qual test requirements could impact the SOF hardware delivery schedule, but this is assessed as low risk.

51. Exercise # 4 Option 4 Risk Issues
Risk Issues: Design Option 4 includes a solid-wall radome, normally used with narrow-bandwidth systems. Potential severe internal heat loads could result from RF energy reflection from the radome. Performance risk is assessed as highly likely to reduce power handling capability by .5 watt.

54. Exercise # 4 Option 5 Risk Issues
Volume: Design consistent with available installation volume
Predicted Unit Cost: $19,460
Risk Issues: Option 5 includes a pressurized radome to achieve an operational altitude greater than required by the specs. However, this design has a history of pressure leak problems. Loss of pressure could result in arcing and system damage impacting performance and reliability. Upgrade to seals and increased leak testing would require additional cost and test time. Assessment indicates probable additional costs would increase AJS unit cost by 10%.

56. See Trade Study Example (Excel)