1. Requirements analysis
Design of UAV Systems
Lesson objective - to discuss
Requirements analysis
including …
Basing
Operational radius
Operational endurance
Maximum range
Speed
Turn around time
plus …
Example problem
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Requirements analysis
8-1

2. Requirements analysis
Design of UAV Systems
Definition
Requirements analysis
Quantitative and qualitative engineering analysis to translate overall customer goals and objectives into a traceable set of “design-to” requirements
Provides the design team with a consistent set of numbers they can work to
Basically a form of “reverse engineering”
Working backwards to determine what combination of concepts, design and technology best meet customer expectations?
Usually a cost and risk-based analysis
What is the highest level of system performance achievable at the lowest cost and risk?
Air vehicle empty weight and payload weight are often used as cost surrogates
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Requirements analysis
8-2

3. UAV system design drivers
Design of UAV Systems
UAV system design drivers
Most top level UAV requirements focus on target area coverage, capability and time
Reconnaissance capabilities are typically defined in terms of types or numbers of targets and sensor resolution
Strike capabilities typically are defined in terms of types, numbers and distribution of targets
For the UAV air vehicle element this typically translates into derived requirements on
Basing
Operational radius
Operational endurance
Maximum range
Speed
Turn around time
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Requirements analysis
8-3

4. The typical basing mode for aircraft
Design of UAV Systems
Land Based Operations
The typical basing mode for aircraft
Other basing options impose penalties
Weight and complexity
…...and/or…..
Operational constraints
Land based operations are supported by over 45,000 airports world wide
But most runways are short and unpaved
Very short fields penalize air vehicle design
Sophisticated high-lift systems are heavy and complex
Unpaved airfields increase the penalty for takeoff, landing and ground operations
Landing gear, wheels and brakes comprise a significant percentage of air vehicle empty weight
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Requirements analysis
8-4

5. Worldwide airport data
Design of UAV Systems
Worldwide airport data
Data Source -
(Total = 45,024)
What runway length do you design for?
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Requirements analysis
8-5

6. What type runway do you design for?
Design of UAV Systems
Typical unpaved field
What type runway do you design for?
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Requirements analysis
8-6

7. It depends on the mission
Design of UAV Systems
It depends on the mission
Example - A Korean venture capitalist sees a market for overnight aerial delivery of small, high value products between Korean and Chinese commercial and industrial airports. An automated UAV delivery vehicle could have cost benefits compared to a manned aircraft.
- He wants to operate out of a hub in Sachon
- He is familiar with the runways in Korea and is confident that they will support his delivery concept
- He is not familiar with the runways in China
- He asks for an initial study to assess UAV takeoff and landing requirements
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Requirements analysis
8-7

8. The results are plotted and compared
Design of UAV Systems
Analysis approach
- We log on to the internet and access the “World Fact Book” at and collect runaway data for China and Korea
- A spreadsheet is created to correlate runway length and type vs. the number of runways per country
The results are plotted and compared
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Requirements analysis
8-8

9. Design of UAV Systems Airport data Airports - China Airports - ROK10 20 30 40 50 60 70 80 90
100
> 10Kft
> 8Kft
> 5Kft
> 3Kft
Total
Runway Length (Kft)
Number (%)
Unpaved
Paved
Airports - ROK 10 20 30 40 50 60 70 80 90
100
> 10Kft
> 8Kft
> 5Kft
> 3Kft
Total
Runway Length (Kft)
Number (%)
Unpaved
Paved
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Requirements analysis
8-9

10. 85% of the airports in China are 5000 feet or longer
Design of UAV Systems
Assessment
Almost all ROK and Chinese airports with runways longer than 3000 feet are paved
- There is no real benefit to having a capability to operate from unpaved fields
85% of the airports in China are 5000 feet or longer
- There is no real benefit to having a capability to operate from shorter fields in China
But only 33% of the airports in the ROK are 5000 feet or longer
Is this enough or should we serve shorter ones?
Answer: Korea is a small country with 54 airports with runways > 5000 feet
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Requirements analysis
8-10

11. Design of UAV Systems Vehicle Implications
A subsonic (low wing loading) jet powered UAV could operate from a 5000 foot runway in either country
A prop powered UAV could be able to operate from a 3000 foot runway in either country
feet is possible for a jet it but requires a very low wing loading or a high thrust-to-weight (or both)
see Raymer, Figure 5.4
Bottom line
A jet powered UAV could operate from 85% of the runways in China and 1/3 of the runways in Korea
A prop powered UAV could operate from >90% of the runways in China and >40% of the runways in Korea
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Requirements analysis
8-11

12. See Raymer, 5.3 through page 103 for more information
Design of UAV Systems
Jet UAV example
Note that takeoff and landing requirements are based on distance over a 50 foot obstacle
See Raymer, 5.3 through page 103 for more information
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Requirements analysis
8-12

13. Unpaved fields are not as bad as they may sound
Design of UAV Systems
Unpaved fields
Unpaved fields are not as bad as they may sound
They are designed for aircraft operations
Typically they are reasonably smooth
- They may not, however, be level
- Nor particularly straight
And they cannot be cleaned
- This is a problem for jet aircraft with engine inlets located near the ground
They also are generally unusable in wet weather
And aircraft with high gross weight/tire contact area ratios can sink into the ground, whether wet or dry
- Runways and taxi ways generally have a LCN (load contact number) rating to indicate how much load/tire contact area can be handled
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Requirements analysis
8-13

14. Unprepared fields are different from unpaved fields
Design of UAV Systems
Unprepared fields
Unprepared fields are different from unpaved fields
An unprepared field can be anything from a soccer field to a muddy pasture
- A requirement to operate from such fields can impose severe penalties on fixed wing aircraft
Low takeoff and landing speeds
Heavy duty landing gear
High flotation tires, etc.
The requirement can be met with a fixed wing aircraft but the result is usually a slow vehicle with a low wing loading (like a Piper Super Cub) or a faster vehicle (e.g. STOVL) with powered lift
- According to Raymer, STOVL weight penalties are 10-20% for fighters and 30-60% for transports
When range and speed are not critical, rotary wing aircraft are better for unprepared field operations
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Requirements analysis
8-14

15. Operating an air vehicle from a ship is complicated
Design of UAV Systems
Operations at sea
Operating an air vehicle from a ship is complicated
Manned fighters and fighter bombers have been operating from aircraft carriers for years
- But deck and air operations are complex
Very high level of pilot proficiency required
Crowded deck space
High potential for accidents and injuries
Helicopters also have been operating from smaller ships for years. Operations are less complicated but still demanding
- STOVL aircraft can also operate from smaller ships
- Fixed wing UAVs have operated from smaller ships with mixed success
Cruise missiles have operated from smaller ships and submarines but they do not recover back to the ship
- UAV/UCAV operations from subs are being studied
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Requirements analysis
8-15

16. Ship based air operations
Design of UAV Systems
Benefits
Ship based air operations
70% of the surface of the earth is covered with water
Operating from ships frees operators from requirements to build or establish land bases
Well equipped ships have housing and provisions for crew members and facilities and spare parts for maintenance and overhaul
Global mobility is enhanced
But the cost is high and the ships involved are large and complex
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Requirements analysis
8-16

17. Design of UAV Systems Aircraft Carriers CVN-68 Nimitz-class
1092 ft (333 m)
252 ft (77 m)
Crew
5680
Fixed Wing Aircraft
14 F-14 Tomcat 4 EA-6 Prowler
36 F/A-18 Hornet 4 E-2 Hawkeye
6 S-3 Viking
Helicopters
8 SH-3 Sea King or..
8 SH-60 Seahawk
Aircraft designed for carrier operations typically pay a 10-15% weight penalty
CVN-68
Nimitz-class
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Requirements analysis
8-17

18. Design of UAV Systems Assault Ships LHD-1 Wasp-class
Crew
1100 Sailors
1900 Marines
Fixed Wing Aircraft
Up to 20 AV-8B Harriers
Helicopters
Up to 42 CH-46
Sea Knight
Only Short Takeoff Vertical Landing (STOVL) aircraft and helicopters currently operate from assault ships
- A fixed wing UAV designed to operate from this class ship would probably use powered lift (10-20% weight penalty)
LHD-1
Wasp-class
252 ft (77 m)
200 ft
(61m)
844 ft (253 m)
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Requirements analysis
8-18

19. Design of UAV Systems Typical assault ship
Decks are crowded and space is limited
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Requirements analysis
8-19

20. Fixed wing aircraft have been launched from other types of ships
Design of UAV Systems
Other surface ships
Fixed wing aircraft have been launched from other types of ships
- Handling is complex and this is not widely used
Regulus s
Pioneer s
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Requirements analysis
8-20

21. The big problem is landing
Design of UAV Systems
UAV ship operations
The big problem is landing
- Current interest focuses on rotary wing UAVs but other concepts are being studied
US Navy VTUAV
Replaces Pioneer
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Requirements analysis
8-21

22. Cruise missiles have been launched from the decks of submarines
Design of UAV Systems
Submarines
Cruise missiles have been launched from the decks of submarines
- Current concepts are torpedo tube launched
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Requirements analysis
8-22

23. Operating UAVs from subs has been demonstrated
Design of UAV Systems
UAV operations
Operating UAVs from subs has been demonstrated
Launching UAVs from subs is being studied
- Size and weight penalties are significant
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Requirements analysis
8-23

24. Launching UAVs from aircraft is straight forward
Design of UAV Systems
Air launch
Launching UAVs from aircraft is straight forward
The UAV benefits are reduced size and weight
Carrier aircraft adds to operational range
Engine can be sized for cruise
Landing gear can be sized for landing weight
But there are limitations on size and weight
Under wing mounted (NB-52 with X-15A-2)
- Length = 52.5 ft, span = 22.5 ft, height = 14 ft
- Weight = 56.1 Klb
Upper fuselage mounted (B747 with Shuttle)
- Length = 122 ft, span = 57 ft, height = 57 ft
- Weight = 180 Klb
Under fuselage mounted (L1011 with Pegasus)
- Length = 55 ft, span = 22 ft, diam. = 4.2 ft
- Weight = 51 Klb
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Requirements analysis
8-24

25. Practical constraints
Design of UAV Systems
Practical constraints
Upper fuselage loading and unloading is very complex
Under wing carriage of large vehicles requires something like a B-52
Unless your customer has such resources, carriage will be constrained to smaller aircraft
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Requirements analysis
8-25

26. Design of UAV Systems More reasonable sizes Orbital Sciences Pegasus
Ryan AQM-34N
Span: 32 ft. Weight: 3,830 lbs.
Length: 30 ft. Speed: 420 mph
Height: 6.75 ft. Range: > 2000 NM
Orbital Sciences Pegasus
Span: 22 ft. Diameter: 4.2 ft.
Length: 55 ft. Weight: 51 Klb
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Requirements analysis
8-26

27. Design of UAV Systems Aerial recovery
AQM-34 reconnaissance drones were recovered in mid air during the Vietnam war
65% of the drones were successfully recovered, many using a Mid Air Retrieval System (MARS) equipped helicopter which performed an aerial “snatch”
Despite past success, aerial recovery is complex and dangerous (for the helicopter)
I can find no pictures of the recovery system but take my word for it, aerial recovery of UAVs is very difficult
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Requirements analysis
8-27

28. Requirements analysis
Design of UAV Systems
Next subject(s)
Lesson objective - to discuss
Requirements analysis
including …
Basing
Operational radius
Operational endurance
Maximum range
Speed
Turn around time
c LM Corporation
Requirements analysis
8-28

29. Operational radius and endurance
Design of UAV Systems
Operational radius and endurance
Why are they important?
Operating radius defines how far the UAV operates from base
- Typically sizes the system architecture (comms, etc.)
Endurance (time on station) and operating radius typically size the air vehicle
Example - Global Hawk (RQ-4A) early program goals
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Requirements analysis
8-29

30. Where did 24 hours and 3000 nm come from?
Design of UAV Systems
RQ-4A question
Where did 24 hours and 3000 nm come from?
They were driven by customer and crew considerations
- UAV products are generally needed around the clock (24 hours a day, 7 days a week)
- Air operations are planned in 24 hour cycles
- Crews operate on 8 or 12 hour cycles*
Original Global Hawk endurance would allow 2 air vehicles to provide 24/7 coverage at 3200 nm with fixed takeoff and recovery times.
3200 nm would allow operations from secure bases far from a combat zone (Diego Garcia - Kuwait = 2640 nm)
* Civilian air crews operate on 8 to 14 hour cycles
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Requirements analysis
8-30

31. Preflight checks and maintenance - Nominal 1.5 hours (est.)
Design of UAV Systems
Expanded explanation
Preflight checks and maintenance
- Nominal 1.5 hours (est.)
Time to taxi and takeoff
- 30 minutes (from NGC)
Time to climb
kts (135 KEAS average) = 1 hr
Time enroute
- 3000nm/350 kts = 8.6 hrs
Time on station
- 24 hours for single vehicle coverage
Enroute return = 8.6 hrs
Time to descend
- Nominal 1 hour (est.)
Landing loiter time
- 1 hour (from NGC)
Time to land and taxi
- Estimate 15 minutes
Post flight checks - Nominal 1.5 hours (est.)
Single vehicle nominal flight + ground time = 48 hours; i.e. one vehicle can launch every 24 hours
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Requirements analysis
8-31

32. Defines how far the UAV can deploy from base
Design of UAV Systems
Maximum range
Why is it important?
Defines how far the UAV can deploy from base
Establishes the support assets required to support deployment
Global Hawk nm range permits self deployment anywhere in the world without aerial refueling
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Requirements analysis
8-32

33. Range and endurance impact
Design of UAV Systems
Range and endurance impact
Range and endurance drive system size, complexity and cost
Range - Communication architecture goes from simple to complicated when range exceeds line of sight (LOS)
LOS (nm) ≈ 0.87sqrt [2H(ft)]
10Kft = 123 nm
65Kft = 315 nm
- Beyond line of sight (BLOS) coverage requires comm relay (surface or airborne) or satellite*
Endurance (time on station) - 12 hour endurance (at 3200 nm) Global Hawk type air vehicle would cost about 60% less (based on empty weight) at same payload
- Maximum range and endurance would drop by 25%
- Number of air vehicles for 24/7 would increase 50%
Examples
* More about this in lesson 9
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Requirements analysis
8-33

34. Number of air vehicles required driven by:
Design of UAV Systems
Fleet size
Number of air vehicles required driven by:
Time on station, operating radius and cruise speed, turn around and other times. Global Hawk example:
- Total ground time = 3.75 hrs, time to climb/descend/land = 3 hrs, time enroute = 2*[op’n radius]/speed =17.5 hrs
If time on station=24 hrs, 2 vehicles req’d, one launch every 24 hours
If time on station=12 hrs, 3 vehicles req’d, one launch every 12 hours
If time on station = 6 hrs, 5 vehicles req’d, one launch every 6 hours
24 hour coverage
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Requirements analysis
8-34

35. Time on station – cont’d Design of UAV Systems
If time on station = 2 hrs, 13 vehicles req’d, one launch every 2 hours
24 hour coverage
* Air vehicle cost excludes payload (which should be included) - more about this later
Design of UAV Systems
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Requirements analysis
8-35

36. Commercial and military considerations functionally similar
Design of UAV Systems
Straight forward assessment of required or desired target area (commercial or military) coverage
Commercial and military considerations functionally similar
Military assessments driven by targets and “threat lay down”
Drive routing considerations (which impacts range req’d)
Commercial assessments driven by target markets and routing
Common considerations
Launch base(s)
Target(s)
Recovery base(s)
Deviations from most efficient routes (great circle)
Both types require geographic area analysis
Typically a problem for individual students
Range analysis
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Requirements analysis
8-36

37. Geographic area analysis
Design of UAV Systems
Geographic area analysis
Efficient assessment of geographic area coverage requires digital mapping software and data bases that are not typically available to students.
Example - A UAV operating out of Seoul, Korea has an operating mission radius of 1200 nm
- How much of the Chinese land mass could it survey?
- How would coverage compare to a UAV with a 600nm operating radius?
- Assume that you do not have time to grid a map and manually count squares
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Requirements analysis
8-37

38. Geographic area coverage?
Design of UAV Systems
Geographic area coverage?
600 nm
1200 nm
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Requirements analysis
8-38

39. - He wants to operate out of a hub in Sachon
Design of UAV Systems
Internet databases are available on airports (numbers, types, and locations). You can use airports as surrogates for geographic area.
Simple solution
Example - A Korean venture capitalist sees a market for overnight aerial delivery of small, high value products between Korea and Chinese commercial and industrial airports. He believes an automated UAV delivery vehicle could have cost benefits compared to a manned aircraft.
- He wants to operate out of a hub in Sachon
- How would we do a requirements study to determine what UAV operating ranges, types and speeds would be required?
c LM Corporation
Requirements analysis
8-39

40. We randomly select 25 Chinese ICAO airports with long runways
Design of UAV Systems
Analysis approach
We randomly select 25 Chinese ICAO airports with long runways
ICAO designations indicate the airports are used for commercial operations
Long runways identify major airports with significant airline operations
We log onto Worldwide Airport Path Finder and start to develop a database.
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Requirements analysis
8-40

41. Design of UAV Systems Example Unfortunately fallingrain.com
no longer maintains this site
This is the output from WAPF at
WAPF has a database of all known airports and allows a user to plan a flight between any airports with ICAO designators. This example is a 52 nm flight from Sachon (RKPS) to Pusan (RKPP).
A data set is created by calculating the distances between Sachon and each of the 25 Chinese airports
The data set is listed in order of distance, from shortest to longest and plotted
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Requirements analysis
8-41

42. Design of UAV Systems The data set ICAO ID Distance(nm) zsqd 381.00
zytl
390.00
zsss
411.00
zshc
488.00
zsnj
499.00
zycc
545.00
zbtj
567.00
zsof
574.00
zsfz
700.00
zhcc
701.00
zhhh
743.00
zbyn
762.00
zsam
817.00
zbhh
841.00
zgha
863.00
zggg
zgkl
zuck
zppp
zuuu
zgnn
zghk
zwww
zwtn
zwsh
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Requirements analysis
8-42

43. Design of UAV Systems The plot
A UAV with an operating radius an 1300 nm can cover 90% of the airports studied. The radius has to double to cover the remaining 10%. Is this the result of the small data base used or does it indicates that a study is needed to determine if covering the last 10% is cost effective?
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Requirements analysis
8-43

44. Does this help you answer?
Design of UAV Systems
Does this help you answer?
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Requirements analysis
8-44

45. Design of UAV Systems Speed Why is it important?
It has a major impact on the cost and complexity of the air vehicle - Speed costs!
Turboprop
Jet
Piston Engine
Data source -
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Requirements analysis
8-45

46. It is what an aircraft gets paid for
Design of UAV Systems
Block time
Why it is important?
It is what an aircraft gets paid for
Passenger or freight customers pay by the trip
Once an aircraft is loaded with freight or passengers, it doesn’t earn any more money until it is loaded again
But from a revenue standpoint, if an aircraft has to sit on the ground for long periods of time between flights, it almost doesn’t matter if it flies fast or slow.
Time on the ground (ground turn around time) is a key mission consideration
We will define block time plus time on the ground as sortie length
c LM Corporation
Requirements analysis
8-46

47. It is the only speed that matters from a revenue stand point
Design of UAV Systems
Block speed
What is it ?
The average speed for an entire mission including takeoff, climb, cruise, descent and landing
Why it is important?
It is the only speed that matters from a revenue stand point
c LM Corporation
Requirements analysis
8-47

48. Sortie length analysis
Design of UAV Systems
Sortie length analysis
ICAO ID
Distance(nm)
zsqd
381.00
zytl
390.00
zsss
411.00
zshc
488.00
zsnj
499.00
zycc
545.00
zbtj
567.00
zsof
574.00
zsfz
700.00
zhcc
701.00
zhhh
743.00
zbyn
762.00
zsam
817.00
zbhh
841.00
zgha
863.00
zggg
zgkl
zuck
zppp
zuuu
zgnn
zghk
zwww
zwtn
zwsh
Sortie length
= time to service, taxi, load & unload + distance/(block speed)
Assumptions
- 1 hour to load and takeoff
- 1 hour to land and unload
- 40 knot headwind
Block speeds
60,120 kts (piston engine)
240 kts (turboprop)
480 kts (subsonic jet)
960 kts (supersonic jet)
Min. coverage
50% coverage
90% coverage
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Requirements analysis
8-48

49. Design of UAV Systems Analysis results
60 & 120 kt UAVs cannot provide overnight service
A 240 kt UAV can make one (1) flight per night (90% coverage)
A 480 kt UAV can fly two (2) 90% coverage missions (one round trip) per night
Or 1 max. distance mission
A 960 kt UAV can fly 3 times per night (90% coverage)
Total time (hr)
Block speed (kts)
Questions
- Which speed is most cost effective?
- What are the sensitivities of the results to the assumption of a 2 hour turn-around time (international flight)?
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Requirements analysis
8-49

50. Lowest cost to meet requirements
Design of UAV Systems
Cost effectiveness
Relative income
= 12hrsBlock time
Relative cost (assumption)
- 60 kt UAV =
- 120 kt UAV =
- 240 kt UAV =
- 480 kt UAV =
- 960 kt UAV = 16.00
Best option = 240 kts
Lowest cost to meet requirements
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Requirements analysis
8-50

51. Design of UAV Systems China - 2 hour turnaround
Total time (hr)
Block speed (kts)
China - 2 hour turnaround
China - 4 hour turnaround
A 240 kt UAV still provides 90% overnight coverage with 4 hours on the ground
With 4 hours on the ground, a 480 kt UAV can now make only one overnight flight with 90% coverage
A 960 kt UAV can make 2 flights per night (one round trip) with 2 hour turn around or 1 flight if ground time is 4 hours.
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Requirements analysis
8-51

52. You should now understand
Design of UAV Systems
Expectations
You should now understand
How simple analysis can provide insight into basic customer requirements
Basing
Time
- Distance
How to develop airport and runway requirements to include length and type
The design implications of operating from unpaved fields, ships and air launch
That requirements analysis is iterative
- Many analyses raise as many questions as they answer
- It is important to explore these issues and to study sensitivities, especially to assumptions
- Area coverage
- Speed
- Turn around time
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Requirements analysis
8-52

53. Requirements analysis
Design of UAV Systems
Next subject
Lesson objective - to discuss
Requirements analysis
including …
Basing
Operational radius
Operational endurance
Maximum range
Speed
Turn around time
plus …
Example problem
c LM Corporation
Requirements analysis
8-53

54. Surveillance UAV - review
Design of UAV Systems
Surveillance UAV - review
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
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Requirements analysis
8-54

55. Review cont’d Design of UAV Systems 200 nm Surveillance area
Loiter location(s)?
100 nm
Surveillance area
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Requirements analysis
8-55

56. Review - Customer asking for?
Design of UAV Systems
Review - Customer asking for?
A system that can monitor a large area of interest
Conduct wide area search (WAS) for 10 sqm ground moving targets (GMT), range resolution  10m. Send back data for analysis within 2 minutes
A system that can provide more data on demand
Based on analysis of wide area search information
Based on other information
A system that can provide positive identification of specific operator selected targets
Within 30 minutes of request at a resolution of 0.5 m
But what is positive identification?
Does it require a picture or will a radar image suffice?
…and what happens to search requirements while the UAV responds to a target identification request?
…and how often does it respond?
…and what is the definition of “all weather”?
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Requirements analysis
8-56

57. Positive identification : “Visual image required”
Design of UAV Systems
Other inputs - review
Customer guidance
Positive identification :
“Visual image required”
Search while responding to target identification request:
“interesting question, what are the options?”
ID response frequency – Assume 1 per hour
Weather definition : “Assume
Clear day, unrestricted visibility (50% of the time)
10Kft ceiling, 10 nm visibility (30%)
5Kft ceiling, 5 nm visibility (15%)
1Kft ceiling, 1nm visibility (5%)
Threshold target coverage = 80%; goal = 100%”
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Requirements analysis
8-57

58. The answer will drive system cost and risk
Design of UAV Systems
Our first decision
Will we give the customer a threshold capability or will we give them what we think they need?
The answer will drive system cost and risk
We bring our team together to discuss and decide
We decide to design our initial baseline for a threshold capability except we will provide a simultaneous wide area search and target identification capability
Our decision is based on subjective analysis
If the system gets one target identification request per hour, a UAV could easily spend all of its time doing target identification
There might be no time left for wide area search
We can do trade studies to evaluate other options
i.e. goal performance capability, etc.
And we need to select a starting concept and document our decisions as “derived requirements”
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Requirements analysis
8-58

59. Candidate system solutions
Design of UAV Systems
Candidate system solutions
One large UAV with long range WAS sensor
Minimum WAS range required for 80% target area coverage = 101nm (187km); h = 53.7 Kft
282 nm in 30 min.
= 564 kts
Target 2 location
to 512 kts
Maximum WAS range = 202 nm (374 km); h > 100 Kft
Communications ranges potentially very long
Up to 316 nm (h > 65 Kft)
Lots of climbs and descents
Loiter location
141 nm in 30 min. = 282 kts
Target 1 location
And high speed required
From 262 kts
100 nm
200 nm x 200 nm
Note – required distance calculations assume no ID sensor range extension
316 nm
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Requirements analysis
8-59

60. WAS range (80% coverage) = 101nm ; h = 53.7 Kft
Design of UAV Systems
Another approach
Two large UAVs, one provides wide area search, the other provides positive target identification
WAS range (80% coverage) = 101nm ; h = 53.7 Kft
One would need very long range communications
Unless the other also served as a communication relay
Comm. distance reduces to
200 nm
Speed requirements could be
reduced if UAVs cooperate &
switch roles
282 kts for both
But frequent climb
and descent required
And UAVs have to operate
efficiently at both altitudes
- Not impossible
200 nm x 200 nm
200 nm
Loiter locations
Target 1 location
141 nm in 30 min. = 282 kts
Target 2 location
c LM Corporation
Requirements analysis
8-60

61. WAS range (80% coverage) = 51nm (95km); h = 27 Kft
Design of UAV Systems
Third approach
Five medium size UAVs, four perform wide area search and ID, a fifth on stays on CAP as gap filler
WAS range (80% coverage) = 51nm (95km); h = 27 Kft
Communications relay distance reduced
To 158 nm
Speed requirement can be reduced to 141 kts if UAVs cooperate and switch
roles
Otherwise 282 kt speed
required
Climb and descent reqmn’ts
reduced
WAS and ID
altitudes closer
Air vehicle altitude
optimization a little
easier
100 nm
200 nm x 200 nm
158 nm
10 Kft
27 Kft
27 Kft
c LM Corporation
Requirements analysis
8-61

62. WAS range (80% coverage) = 26nm (48km); h = 14 Kft
Design of UAV Systems
Yet another approach
Twenty small UAVs, sixteen provide wide area search, four provide positive target identification
WAS range (80% coverage) = 26nm (48km); h = 14 Kft
Communications relay distance reduced
To 127 nm
Speed requirement can be reduced to 70 kts if UAVs cooperate and switch roles
Otherwise 141 kt speed
required
Climb and descent reqmn’ts
eliminated
WAS and ID
altitudes similar
Air vehicle design
optimization easy
Use Predator
But large numbers required
100 nm
200 nm x 200 nm
127 nm
c LM Corporation
Requirements analysis
8-62

63. WAS range required (95km) not a challenge
Design of UAV Systems
Our starting approach
Five medium UAVs, four provide wide area search, a fifth provides positive target identification
WAS range required (95km) not a challenge
But only one UAV responds to target ID requests
No need to switch roles, simplifies ConOps
No need for frequent climbs and descents
Speed requirement = 282 kts
Air vehicle operating altitude differences reasonable
We can study the
other options as trades
100 nm
200 nm x 200 nm
158 nm
27 Kft
10 Kft
c LM Corporation
Requirements analysis
8-63

64. Defined requirements (from the customer)
Design of UAV Systems
Requirement summary
It is important to maintain an up to date list of requirements as they are defined or developed
Defined requirements (from the customer)
Continuous day/night/all weather surveillance of 200nm x 200nm operations area 100 nm from base
Detect 10 sqm moving targets (goal = 100%, threshold = 80%), transmit 10m resolution GMTI data in 2 min.
Provide 0.5 m resolution visual ID of 1 target per hour in 15 min (goal = 100%, threshold = 80%)
Operate from base with 3000ft paved runway
Cloud ceiling/visibility
Clear day, unrestricted
10Kft ceiling, 10 nm
5Kft ceiling, 5 nm
1Kft ceiling, 1nm
Percent occurrence
50%
30%
15%
05%
Atmospheric conditions (customer defined)
c LM Corporation
Requirements analysis
8-64

65. Design of UAV Systems Derived requirements
Derived requirements (from our assumptions or studies)
System element
Maintain continuous WAS/GMTI coverage at all times
Assume uniform area distribution of targets
Communications LOS range to airborne relay = 158 nm
LOS range from relay to surveillance UAV = 212 nm
Air vehicle element
Day/night/all weather operations, 100% availability
Takeoff and land from 3000 ft paved runway
Cruise/loiter altitudes = 10 – 27Kft
Loiter location = 158 nm (min) – 255 nm (max)
Loiter pattern – 2 minute turn
Dash performance = Kft
Payload weight and volume = TBD
Payload power required = TBD
c LM Corporation
Requirements analysis
8-65

66. Design of UAV Systems Derived requirements Payload element
Installed weight/volume/power = TBD
WAS
Range/FOR /resolution/speed = 95 km/45/10m/2mps
Uninstalled weight/volume/power = TBD ID
Type/range/resolution = TBD/TBD/0.5m
Communications
Range/type = 212nm/air vehicle and payload C2I
Range/type = 158nm/communication relay
Control Station element
TBD
Support element and sortie rates
To be determined
C2I = Command Control and Intelligence
c LM Corporation
Requirements analysis
8-66

67. Minimum header information Design project name Student name
MIEOE requirements*
Design of UAV Systems
Minimum header information
Design project name
Student name
Homework lesson number
Homework problem number
Submit electronically by COB (1700) Thursday before class
Bring paper copy to class (and turn it in)
* Make It Easy On Edgar = how to get your homework graded
c LM Corporation
Requirements analysis
8-66a

68. H(1) How many vehicles are required? Explain why
Design of UAV Systems
Homework
Do a first-order requirements analysis on your UAV system project and select an initial system concept
H(1) How many vehicles are required? Explain why
((2) What speeds and altitudes are required?
- Document the calculations that support your conclusions including intermediate steps.
D(3) Develop an initial list of defined and derived requirements
- Use the example problem as a guide
Submit your homework via to Egbert by COB next Thursday
c LM Corporation
Requirements analysis
8-67

69. Intermission Design of UAV Systems c 2003 LM Corporation
Requirements analysis
8-68