1. System Design Design of UAV Systems Objectives
c LM Corporation
Objectives
Lesson objective - to review the concept of
System Design
including...
What is it?
How is it different from other design?
Discuss related concepts
Requirements
Defined and Derived
Performance
Allocated and Status
How to start the process
What are the expectations?
Semester student design projects
Example problem
Homework
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2. System Design Design of UAV Systems Definition
c LM Corporation
Definition
System Design
Design of a complete system - example, a UAV system and all of its elements
Air vehicle including
Airframe
Engine
Avionics
Software
Etc.
Communications
Control station
Payload
Support system
Training
Logistics
System Design addresses requirements and their
design implementation
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3. Requirement Design of UAV Systems Definition
System Design
c LM Corporation
Definition
Requirement
What a product must or should do (i.e. the documented expectations for a design)
Example - The mission system software must must employ an open system architecture or ….
The average unit cost for production units should not exceed $10 million
Documents customer, program, functional and designer expectations
Requirements include performance, cost, schedule and risk.
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4. Requirements based approach
Design of UAV Systems
System Design
c LM Corporation
Another definition
Requirements based approach
The design of a product from the “Top-Down” - a downward looking activity
From the highest level of definition to its many layers of subsystems
At the top-most level - driven by customer expectations and needs
Called “defined requirements”
At every other level - driven by what is required to meet higher level requirements
Called “derived and/or allocated requirements”
This is the essence of Systems Engineering
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5. High Altitude Endurance (HAE) UAV top-level system requirement
Design of UAV Systems
System Design
c LM Corporation
Example - defined requirement
High Altitude Endurance (HAE) UAV
top-level system requirement
Provide effective all-weather surveillance of 40,000 square miles in 24 hours at an operating radius of 3000 nm using altitude and standoff distance to enhance survivability.
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6. Example - design solution
Design of UAV Systems
System Design
c LM Corporation
Example - design solution
This is not a very good example of a defined requirement
Global Hawk’s only defined requirement was cost <$10M
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7. Example - derived requirements
Design of UAV Systems
System Design
c LM Corporation
Example - derived requirements
Air vehicle
- Operating altitude - 65,000 feet
- Maximum range - 14,000 nm
- Maximum endurance - 42 hours
- 1 loss in 200 missions
- Etc.
Airframe
- 25,600 lb gross takeoff weight
- 9,200 lb empty weight
- Cruise L/D = 33-35
Engine
- Unmodified existing turbofan
- Installed thrust (SLS) = 7900 lbf?
- Installed thrust (65Kft) = 750 lbf?
 Generator
- Output power = Z
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8. Example - design solution
Design of UAV Systems
System Design
c LM Corporation
Example - design solution
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9. Other requirement types
Design of UAV Systems
System Design
c LM Corporation
Other requirement types
There are two other types of requirements and they must never be confused
Threshold Requirement - the minimum level of acceptable performance
Goal Requirement - the maximum level of desired performance
What customers are telling you when they define goals and thresholds
If your design does not meet threshold levels it is unacceptable
If your design exceeds goal performance you get no benefit (it is “gold plated”)
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10. Threshold Requirement
Design of UAV Systems
System Design
c LM Corporation
Expanded definition
Threshold Requirement
- The lowest level of performance acceptable for of a design. If performance is below a threshold, the design must be changed. If redesign cannot solve the problem within defined cost and risk, something else has to change.
Example - You are responsible for airframe design. Your customer has established a UAV threshold design mission range of miles. Your project chief systems engineer has allocated you an airframe a weight of 9,200 lbs. When performance is calculated, you discover the airframe weighs 9,200 lbs but it can only fly 12,0000 miles. Your design team has to make a design change
The deficiency is in a defined requirement (range)
If the deficiency were in a derived requirement (e.g. weight), you might request an increased weight allocation (which might be denied) to allow increased size. The best solution - optimize the existing design to get better performance or try different designs
What you cannot do is hide the problem and hope that you can fix it later.
Engineering ethics !
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11. Design of UAV Systems Expanded definition Goal Requirement
System Design
c LM Corporation
Expanded definition
Goal Requirement
- The highest level of performance needed from a design. If a goal is exceeded, (1) the design is resized until it meets the goal or (2) the design is retained and the excess performance is turned into margin.
Example - You are responsible for airframe design. Your UAV has a goal mission range of miles and an allocated airframe weight of 9,200 lbs. When performance is calculated, your team discovers it weighs 9,200 lbs but it can fly15,0000 miles. The design team (airframe, payload, support, etc.) has choices, two of which are:
1. Reduce the size of the airframe or…...
2. Hold the size and define a performance margin to cover an unexpected (but probable) future performance loss
What you cannot do is to hide the excess performance from the rest of the design team to provide a private margin for unexpected airframe problems.
Engineering ethics !
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12. Performance, cost and risk are all related.
Design of UAV Systems
System Design
c LM Corporation
Performance
In this course, “performance” can mean more than technical performance (e.g. lift-to-drag ratio). It can also mean cost and risk.
Performance, cost and risk are all related.
An example, a UAV might meet a mission range requirement by (1) increasing wing thickness (increased fuel capacity), (2) by using expensive (but existing) advanced materials materials or (3) by developing a potentially low cost (but risky) fuel transfer system to maintain an optimum center of gravity location in flight.
The designer has responsibility to address solutions across all three areas.
This can only be done if the designer (and everybody else on the project) understands the requirements in all three areas - technical performance, cost and risk.
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13. This is your design space
Design of UAV Systems
System Design
c LM Corporation
Performance types
There are two types of performance and they also must never be confused
Allocated performance - the level of performance desired for a design to meet overall requirements. Allocations are expressed in terms of thresholds and goals and they trace directly to requirements
Status performance - the level of performance actually calculated for your design
What the project is telling you when they allocate performance thresholds and goals
This is your design space
What the design is telling you when you get status performance
This is what the laws of physics say about how your design performs
Engineering ethics !
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14. Example - Goals vs. Status
Design of UAV Systems
System Design
c LM Corporation
Example - Goals vs. Status
STATUS
GOAL
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15. Sometimes goals change
Design of UAV Systems
System Design
c LM Corporation
Sometimes goals change
International Briefing, August 1999
Endurance at 3200 nm : 24 hrs
January
2001
• Performance Goals
– Range: 12,500 nmi
– Endurance: 35 hrs
– 24 hrs
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16. “Performance” measures
Design of UAV Systems
System Design
c LM Corporation
“Performance” measures
Another important performance issue is to make sure our design “performance” levels meet requirements
All systems, whether simple or complex, have multiple elements designed to meet multiple requirements
…and which are drivers and which “fall out”
Example – Thrust required for takeoff may “fall out” of thrust required to meet an acceleration requirement
It is also important to identify which are most critical
While it is important to monitor all “tracking performance parameters” (TPMs), the most critical or “key performance parameters” (KPPs) need focused attention and visibility
Therefore, we identify a small number (5-10) of KPPs for system level attention and related sets of TPMs for attention at every other level of the system design
This ensures that the entire team is focused on the most critical issues at all times and at all levels of the design
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17. Question - What does the system design process produce?
Design of UAV Systems
System Design
c LM Corporation
System Design Product
Question - What does the system design process produce?
A product?
A design?
Something else?
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18. Answer - DOCUMENTED TECHNICAL DECISIONS
Design of UAV Systems
System Design
c LM Corporation
System Design Product
Answer - DOCUMENTED TECHNICAL DECISIONS
The primary product of any design process
- Everything else (including design, analysis and test) substantiates design decisions
What the decisions are (drawings and text)
Data to convince others that the decisions are correct (test and analysis results)
Rationale behind the decisions (results of trade-off studies)
Instructions on how to implement the decisions (drawings and specifications)
Without good documentation, the product is useless
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19. Expanded list Design of UAV Systems
System Design
c LM Corporation
Expanded list
System design is about more than concepts and analysis – it is also about planning
(1) Design decisions
(2) Documentation
Requirements
Defined
Derived
ConOps
Description
Effectiveness
System description
Physical
Functional
Performance substantiation
Analysis
Test data
Design rationale/trades
Figures of merit
KPPs and TPMs
Cost
Development
Production
Operations & support
Risk assessment
Identification
Mitigation
Fall back planning
Development plans
Test & evaluation
Concept/technology demonstrator
Prototype
Initial production
Pre-planned product improvement
(3) Simulation
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20. How to start a system design
Design of UAV Systems
System Design
c LM Corporation
How to start a system design
1.Define a baseline system concept - System Engineer leads team to decide initial requirements and concepts for
- System
- Airframe
- Payload
- Mission control
Support
2. Develop good initial pre-concept design
Trade requirements and fully explore potential approaches
3. Cycles (1-2) repeat until concept converges …..
4. Develop Initial Preferred System Concept - System Engineer leads functional teams in definition of initial baseline
- Each team proposes their design approach
- All teams discuss and reach agreement (Lesson 2c)
- Individual teams define designs to appropriate level for analysis
- Individual teams analyze their designs and report results
- System Engineer leads effort and assesses system effects
At this point, customers often define project cost, risk and schedule
- The engineering supporting these estimates better be good!
- We will use our parametric methods to ensure good up front decisions
Customer leads
- Design team supports
Design team leads
- Customer supports
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21. 5. Assess initial system concept design-analysis results
Design of UAV Systems
System Design
c LM Corporation
How to start (cont’d)
5. Assess initial system concept design-analysis results
Led by System Engineer
Allocated vs. status performance presented
Some areas will be better than allocated
Some areas will be worse
Problems and potential solutions are discussed and documented
Trade studies to improve performance are proposed and agreed
Revised allocations are discussed and agreed
6. Systems Engineer documents new allocations
7. Cycles (4-6) repeat until design converges ….. (sometimes to an acceptable conclusion)
8. Upon convergence, teams evaluate other options until overall system converges to better performance. Studies continue until improvement stops or budget runs out
9. Results are documented and presented to customer
10. Team has party and many beers are consumed
Design team leads
- Customer supports
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22. You should now understand the concept of system design
Design of UAV Systems
System Design
c LM Corporation
Expectations
You should now understand the concept of system design
1. Design follows requirements
2. Requirements define what a system needs to do as appropriate for each design phase
3. Requirements do not document a design on an after-the-fact basis
4. Design solutions are traded to ensure that they reflect the best balance of cost, risk and performance
5. Design solutions (and performance) should not be dictated (by the boss or individual designers)
Today requirements also evolve with the design
Even threshold requirements are subjected to trade off studies!
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23. Next subject - Student projects
Design of UAV Systems
System Design
c LM Corporation
Next subject - Student projects
Next generation tactical UAV (TUAV)
- Support army/marine type ground operations
Maritime search UAV
- Support navy/coast guard type operations
Standoff intelligence, surveillance and reconnaissance (ISR) UAV
- Global Hawk follow-on type
Penetrating ISR UAV
- Dark Star follow-on type
Air-to-ground combat UAV (UCAV)
- X45 follow-on type
- You will select one of the five as a semester design project
- It will also be the basis for your homework problems
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24. Design of UAV Systems Next generation TUAV
System Design
 2002 LM Corporation
Next generation TUAV
Forward based operations from 3000 ft paved runway
Provide continuous (24x7) day/night/under weather near real time ISR coverage of 100 nm x 100 nm operations area
Able to resolve range of ground moving targets to 10 m anywhere within combat area and transmit detection data within 2 minutes
Able to provide on-demand positive identification of friendly troops vs. opponent forces (req’d resolution = cm) and transmit imagery to base and/or infantry units within 3 minutes of request
UAV squadron is based within 70 nm of combat areas
Each squadron provides simultaneous support of 10 infantry units, each operating in 10nm x 10 nm combat area
Ignore survivability effects
Minimum required trades
Communication architecture
Sensor(s) required
Control architecture
Operating altitude(s)
Time on station
Air vehicle size and numbers
Air vehicle speed(s)
Propulsion type and size
Aspect ratio
Wing Loading
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25. Design of UAV Systems Next generation TUAV 10 nm Combat area 70 nm
System Design
 2002 LM Corporation
Next generation TUAV
10 nm
Combat area
70 nm
100 nm
50 nm
Base
Area of operations
100 nm
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26. Design of UAV Systems Maritime search UAV
System Design
 2002 LM Corporation
Maritime search UAV
Land based with 5000 foot paved runway
- Squadron is based on the coast
- Able to provide continuous day/night/all weather near real time search capability of 100 x 100 nm ocean surveillance area
Able to launch on distress call or operate from loiter during periods of heightened alert (24 hrs day/7 days a week)
Able to resolve range of 10 sqm moving targets to 10 m within surveillance area and transmit movement within 2 minutes
- Able to put sensors on target anywhere within search area and transmit image within 15 minutes or less
- Able to ID small boat (req’d resolution = m) and identify occupants as friendly (req’d resolution = cm)
- Ignore survivability effects
Minimum required trades
- Communication architecture
Sensor(s) required
Control architecture
Operating altitude(s)
Time on station
Air vehicle size and numbers
Air vehicle speed(s)
Propulsion type and size
Aspect ratio
Wing Loading
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27. Design of UAV Systems Maritime search UAV Search area 100 nm Base
System Design
 2002 LM Corporation
Maritime search UAV
Search area
100 nm
Base
Loiter location(s)?
100 nm
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28. Design of UAV Systems Stand off UAV
System Design
 2002 LM Corporation
Stand off UAV
Land based with 5000 foot paved runway
Provide continuous (24x7) day/night/under weather near real time ISR coverage of 100 nm x 100 nm surveillance area
Able to resolve range of ground moving targets to 10 m anywhere within surveillance area and transmit detection data within 2 minutes
Able to provide on-demand positive identification of 0.5m x 0.5m targets and transmit imagery within 10 minutes
UAV is based within 200 nm of combat area
Ignore survivability effects
Minimum required trades
Communication architecture
Sensor(s) required
Control architecture
Operating altitude(s)
Time on station
Loiter pattern and location
Air vehicle size and numbers
Air vehicle speed(s)
Propulsion type and size
Aspect ratio
Wing Loading
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29. Design of UAV Systems Stand off UAV 100 nm Surveillance area 200 nm
System Design
 2002 LM Corporation
Stand off UAV
100 nm
Surveillance area
Loiter location(s)?
200 nm
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30. Design of UAV Systems Penetrating UAV
System Design
 2002 LM Corporation
Penetrating UAV
Land based with 5000 foot paved runway
Provide continuous (24x7) day/night/under weather near real time ISR coverage of 100 nm x 100 nm surveillance area
Able to resolve range of ground moving targets to 10 m anywhere within surveillance area and transmit detection data within 2 minutes
Able to provide on-demand positive identification of 0.5m x 0.5m targets and transmit imagery within 20 minutes
UAV is based within 200 nm of combat area
Ignore survivability effects
Minimum required trades
Communication architecture
Sensor(s) required
Control architecture
Operating altitude(s)
Time on station
Loiter pattern and location
Air vehicle size and numbers
Air vehicle speed(s)
Propulsion type and size
Aspect ratio
Wing Loading
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31. Design of UAV Systems Penetrating UAV 100 nm Surveillance area
System Design
 2002 LM Corporation
Penetrating UAV
100 nm
Surveillance area
Loiter location(s)?
200 nm
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32. Design of UAV Systems Air-to-ground UCAV
System Design
 2002 LM Corporation
Air-to-ground UCAV
Land based with 5000 foot paved runway
Provide continuous (24x7) day/night/under weather ground attack capability against 10 sqm ground moving targets within a 100 nm x 200 nm operating area
- Able to put eight 500 lb precision guided (GPS) bombs on operator selected target within15 minutes
- Able to provide operator with positive identification of 0.3m x 0.3 m resolution targets prior to weapons release
UCAV is based within 200 nm of combat area
Ignore survivability effects
Minimum required trades
Communication architecture
Sensor(s) required
Control architecture
Operating altitude(s)
Time on station
Loiter pattern and location
Air vehicle size and numbers
Air vehicle speed(s)
Propulsion type and size
Aspect ratio
Wing Loading
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33. Design of UAV Systems Air-to-ground UCAV 200 nm Target area 100 nm
System Design
 2002 LM Corporation
Air-to-ground UCAV
200 nm
Target area
100 nm
Loiter location(s)?
200 nm
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34. How to approach the problem How to apply design and analysis methods
Design of UAV Systems
System Design
c LM Corporation
Example problem
We will use a one continuous example problem throughout the semester to demonstrate:
How to approach the problem
How to apply design and analysis methods
First half focus: System requirements analysis
- Target coverage
- Time on station and response time
- Sensor size and performance
- Communications architecture and bandwidth
- Payload type, size and performance
- Manpower
Second half focus: Air vehicle and design trades
- Air vehicle size and configuration trades
- Propulsion cycle and trades
- Performance and technology
- Effectiveness
- Cost effectiveness and system optimization
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35. Example - surveillance UAV
Design of UAV Systems
System Design
c LM Corporation
Example - surveillance UAV
Predator follow-on type
Land based with 3000 foot paved runway
- Mission : provide continuous day/night/all weather, near real time, monitoring of 200 x 200 nm area
- Basing : within 100 nm of surveillance area
Able to resolve range of 10m sqm moving targets to 10m and transmit ground moving target (GMT) data to base in 2 minutes
- Able to provide positive identification of selected 0.5m x 0.5 m ground resolved distance (GRD or “resolution”) targets within 30 minutes of detection
- Ignore survivability effects
Minimum required trades
Communication architecture
Sensor(s) required
Control architecture
Operating altitude(s)
Time on station
Loiter pattern and location
Air vehicle size and numbers
Air vehicle speed(s)
Propulsion type and size
Aspect ratio
Wing Loading
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36. Design of UAV Systems Surveillance UAV 200 nm Surveillance area 200 nm
System Design
c LM Corporation
Surveillance UAV
200 nm
Surveillance area
200 nm
Loiter location(s)?
100 nm
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37. (1) Select one of the 5 student projects
Design of UAV Systems
System Design
c LM Corporation
Homework assignment
(1) Select one of the 5 student projects
The one that interests you most
All are of approximately equal complexity
During the first half of the semester you will work as a team of one to define your overall system
During the second half, you will work on (or lead) a team to define the air vehicle and optimize the system
Team projects (and leads) will be based on mid-term presentations
The most feasible projects will be selected for continuation
(2) Send Egbert a “capability” (1 page max)
Which project you would like to work on
Why you want to work on it
c. What unique skills and capabilities you think you have that are applicable to the selected problem
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38. Design of UAV Systems Intermission System Design c 2002 LM Corporation
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