Lesson objective to discuss

1

• Lesson objective to discuss
• Concepts of operation
• including
• Basic concepts
• Area coverage
• Combat air patrol
• Response time
• Example problem

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Review

• Concept of operations (ConOps) definition(s)
• How something is used or operated
• Typically associated with military systems but
  also applicable to commercial systems.
• The name of a document used to describe how a
  system should be operated, e.g.

• Which definition will we use?
• What is another way to describe it

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How UAVs are used
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Examples
Tom Cat
www.fas.org/irp/program/collect/docs/97-0230D.pdf
DarkStar
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Air operations

• Whether, manned or unmanned, there are two
  general types of missions, preplanned and
  on-demand
• Preplanned missions are scheduled well in advance
• On demand missions can be launched quickly
  (within minutes) if an aircraft is ready and a
  crew is on site
• - The military does strip alert and standby
  alert missions
• - Strip alert pilots are in the cockpit, ready to
  go
• There are two basic types of loiter missions -
  standoff and over flight (or penetration)
• Standoff missions generally are flown when over
  flight is not allowed or is considered too risky
• Exceptions are missions flown with sensors that
  do not look straight down such as synthetic
  aperture radar (SAR)
• Although missions can takeoff from one base and
  land at another, typically we design for single
  base operations

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Typical mission profile
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Target area coverage from base
Platform only Ap (?p)Rp2 -Tan(?p)Db2
(5.1) where ?p (radians) ArcCos(Db/Rp)
(5.2) Rp Platform radius Db Distance to
border
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Coverage area example
For Db 250 nm Rp 500 nm Platform
only coverage ?p ArcCos(250/500) 60
deg Xmax 433 nm Ap (60?/180)5002-250433
153549 nm2
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UAV vs. manned operations

• Military UAV missions can be planned and operated
  like manned aircraft if they stay in military air
  space
• Flights can be scheduled one day and flown the
  next or, in time critical situations, launched on
  demand
• But manned operations sometimes cease when they
  are unfamiliar with UAV launch and recovery
  operations
• If UAVs have to fly in civilian or international
  airspace, planning may have to be days to weeks
  in advance
• - To allow time for coordination with local
  civilian air traffic control and VFR traffic
• Most manned military missions are for training
• - Pilots need proficiency flying (20 hrs/month)
• Reconnaissance UAVs operate differently, after
  initial training, most missions are operational
• UCAVs were to be even more different, keep them
  in storage until needed for combat (train on
  simulators)

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Sensor coverage

• Some sensors are fixed (called staring sensors)
• - Photo reconnaissance cameras are often fixed
• - Staring sensors also used for self defense
• Others are essentially fixed (e.g.
  line-scanners)
• - The sensor rotates, target coverage is in thin
  strips which can be integrated over time to form
  an image
• - They can provide horizon-to-horizon coverage
• Some sensors are fixed in one direction and can
  be slewed in another (e.g. side looking radar)
• - Horizontal coverage controlled by vehicle
  flight path, elevation controlled independently
• Other sensors can be slewed in azimuth and
  elevation but only within limits (e.g. SAR)
• The most flexible sensors are fully gimbaledin
  azimuth and elevation and can cover an entire
  hemisphere (or more)

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Platform sensor coverage
Same logic as platform only except sensor (or
weapon) can extend target area coverage
Intl waters
Example Db 250 nm Rp 500 nm Rs
75 Platform sensor ?pps
ArcCos(250/575) 64.23 deg Xmax 518 nm Ap
(1.121)5752-250518 241139 nm2 (vs
153549 nm2 for platform only)
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Weapon coverage

• There are a wide variety of weapons types, both
  powered and unpowered
• - Powered weapons can extend target coverage from
  a little (free fall bombs) to a lot (cruise
  missiles)
• Almost all weapons are launched forward
• - Sonabouys and parachute delivered weapons are
  exceptions
• Guided weapons can attack targets well off of the
  flight patch axis
• Some weapons can be aimed like sensors
• - Machine guns and grenade launchers
• Some future weapons will also be aimed
• Lasers

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Loiter missions
Manned military reconnaissance missions loiter
over friendly territory - Sensors can look into
neighboring territory without endangering the
crew (in general) Manned strike missions are
flown both ways - Stealth aircraft are designed
for over flight but they seldom loiter over
hostile territory Unmanned military
reconnaissance (and strike) missions are also
flown both ways - Global Hawk is designed to
loiter over friendly territory - Dark Star was
stealthy and designed to fly over hostile
territory (UCAV will also operate this way) -
Predator is not a stealthy design but often
loiters over hostile territory - It takes a
calculated risk (and is sometimes lost)
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Standoff vs. over flight
Sensors - Sensors on penetrating platforms can
look down and all around - Inherently, they can
cover more target area than a standoff
sensor Weapons - Weapons on penetrating
platforms have the same advantages
Border
Penetrate
Standoff
Sensor Coverage Capability
Standoff distance
Unusable sensor coverage
Border
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Loiter patterns
Plus many others and combinations thereof
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Search area coverage
Straight line coverage Area Swath?Speed?Time Eq
uivalent range Area/Swath
Search pattern coverage K?Area
Swath?Speed?Time Typical factor (K) 1.3?
or
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Combat Air Patrol (CAP)

• Target area coverage (and response time) from a
  CAP type mission is a bit complex and not well
  understood
• In this type mission, the air vehicle loiters
  over an area until it receives and order to
  observe or attack an area of interest
• Assumed to be at maximum fly-out distance
• Upon arrival over the target area, the air
  vehicle performs its mission and then returns to
  base
• The flight path, therefore, is triangular
  consisting of
• - An outbound segment to the CAP location
• - Another segment to maximum distance
• - A third segment back to base
• Typically the CAP location is over friendly
  territory and we will call it a loiter/penetrate
  mission

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Loiter/penetrate geometry - optional

• Definitions
• D1D2D3 2R - LED 2R (5.3)
• where
• D3 Distance back to base
• R Mission radius
• LED Loiter equivalent distance
• ?2max ArcCos(Dso/D2max) (5.4)
• From geometry
• D1 D2min D3max (5.5)
• (D1-Dso)2Xmax2 D3min2 (5.6)
• Dso2Xmax2 D2max2
• therefore
• (D1Dso)2- D3min2 Dso2-D2max2
• and

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Solution approach

• Platform only coverage
• Define LED
• Solve for D2min (10.9)
• Solve for D2max (10.11)
• Solve for ?2max (10.8)
• Solve for D3min (10.10)
• Numerically integrate sector area
• from ?2 0 to ?2max
• where ??2 ?2max/n
• n number of integration steps
• note
• D2' 2R -LED - D1 - D3 (5.8)
• and
• D3 can be solved using the same approach used to
  solve for D2max
• Subtract triangular area defined by Dso, Xmax
  and D2max

Optional topic
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Platform coverage example

• Solve for maximum area coverage
• (LED 300nm) where
• R 650nm
• Db 250 nm
• Dso -125nm
• Solution steps
• D2min 375nm
• D2max 410.7nm
• ?2max 72.3 deg
• D3min 464.3 nm
• Numerically integrate sector area from ?2 0 to
  72.3 deg (n10)
• Sector area 188767 sqnm
• Subtract triangular area defined by Dso, Xmax and
  D2max (48907sqnm)
• Total area 139860 sqnm (vs 153549 nm2 for
  conventional mission)

Optional topic
?2max
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Approximate solution

• R 650 nm
• LED 300 nm
• Db 250 nm
• Dso -125nm
• therefore
• D2min 375nm
• D2max 410.7nm
• ?2max 72.3 deg
• D3min 464.3 nm
• Circular sector area (?2 0 to 72.3 deg)
• Average radius 393 nm
• Sector area 194895 sqnm
• Subtract triangular area defined by Dso, Xmax and
  D2max (48907sqnm)
• Approximate area
• 146078 sqnm (4.5)

Optional topic
?2max
The approximation is valid for loiter penetrate
only
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Figures of merit

• During pre-concept and conceptual design, simple
  figures of merit are typically used
• Examples
• Operational time on station - Global Hawk goal
  24 hours at a distance of 1200 nm from base
• Target area coverage per unit time - Global Hawk
  wide area search goal 40,000 sq.nm/day
• - With 10 km sensor swath width at 343 kts at 10
  overlap (Area Swath?Speed?24? 0.9)
• Number of targets per unit time - Global Hawk
  goal target coverage 1900 2Km x 2Km spot
  images/day
• But some ConOps require different metrics
• Increasingly the figure of merit of interest is
  area coverage within a given response time

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Response time example
Response time (Tr) - The time required to respond
to a request or order such as - Put platform
overhead, put sensor on target or put weapon on
target
Platform response time On alert
(pre-assigned) Tr TseTttoTclTcrTpen where T
se time to start engines ( 5 min) Ttto time
to taxi takeoff ( 10 min) Tcl time to climb
Dcl/Vcl Tcr time to cruise Db?/Vcr-Tcl Tcr
time to penetrate Dpe?/Vpe
On standby (not assigned) Tr?
TrTprep where Tprep additional preparation
times including Aircraft prep (1-2 hrs) Crew
transit (2-4 hours) Mission planning (15-60
min) Flight plan coordination (45 min)
Tr 3 to 6 hrs (_at_ minimum)
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Response time effects

• Sensors
• Sensors arrive on target before the platform (_at_
  speed of light)
• - Target coverage is increased by the range of
  the sensor at any given time
• Weapons
• If a weapon is faster than the platform - the
  weapon will arrive over target first and response
  time improves
• If the weapon is slower coverage area may
  increase but at a slower response time

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Figures of merit
Platform only example

• For a specific missions with specific response
  time requirements, a calculation that includes
  all of the individual time increments and shows
  that the requirement can be met, will be the
  primary figure of merit.
• For more generalized missions, target coverage as
  a function of time, can be a good figure of merit
• - For example, Xsqnm target coverage within Y
  minutes

Border
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Operating distance effects

• The closer an air vehicle loiters to its target
  area, the more efficiently it can employ its
  sensors and the quicker it can respond to
  assignments or requests
• It does, however, reduce target area coverage
• - It is a simple matter of geometry for a vehicle
  with a fixed range or radius

Example
Total mission radius 650 nm
LED 300 nm
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Next subject

• Lesson objective to discuss
• Concepts of operation
• including
• Basic concepts
• Area coverage
• Combat air patrol
• Response time
• Example problem

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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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Surveillance UAV
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Our example how to start?

• Analyze the problem
• What is the customer really asking for?
• What information is missing?
• Look at some potential solutions
• What are the overall system design drivers?
• ConOps
• Communications
• Payload
• Pick an initial approach (or starting baseline)
• Define requirements
• Analyze it
• Estimate cost and effectiveness
• Analyze the other approaches
• Compare results
• Select a baseline approach
• Reasonable balance of cost, risk and effectiveness

Today
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What is the customer asking for?

• A system that can monitor a large area of
  interest
• Conduct wide area search (WAS) for 10 sqm ground
  moving targets (GMTI), 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 (ID)?
• 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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Example - WAS sensor data
Typical high resolution spot time 45 sec
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Example - ID sensor data
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Getting answers

• Ask the customer
• But dont always expect a definitive answer
• Some typical responses
• 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
• Note a measure of effectiveness just got defined!

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Sensor target coverage

• WAS all weather sensors
• Assume minimum look down angle (?) 5?
• Assume maximum look down angle (?) 60?
• ID sensors (against 2D ground target)
• Assume nominal maximum slant range 30 nm
• For reasonable resolution against typical ground
  targets (with high resolution sensor)
• Assume minimum look down angle (?) 20?

Min range Rmin
Max range Rmax
h altitude
?
?
h(reqd) Rmax?Tan(?)
Slant range - min
SLRmax Max slant range
?
Strip width (w)
GMTI coverage area ? h2?1/Tan(?)2-1/Tan(?)2

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WAS ConOps

• If a UAV loiters over a fixed point in the middle
  of a square surveillance area, it can meet an 80
  coverage, 2 minute wide area surveillance (WAS)
  moving target detection requirement if
• It makes 2 minute turns (assuming a nominal ?45
  degree azimuthal field of regard or FOR)

• And the image processing plus transmit time is
  held to 30 seconds or less
• 2. The WAS range is slightly larger than ½ the
  width of the surveillance area
• Area of circle?square ?/4 0.785
• 3. It has a 100 detection rate,100 of the time

Target
FOR
Min range effects ignored
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Positive ID ConOps

• We have a threshold requirement for positive
  (visual image) target identification (ID) 80 of
  the time
• To design our baseline for the threshold
  requirement
• We have to be able to ID targets at or below 10
  Kft what percentage of the time?
• 50 of the time we can stay at higher altitude
  and of the time we wont see a target
  unless we operate at even lower altitudes

Answer - at least 30
20
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ConOps assessment

• The WAS and ID mission requirements are in
  conflict
• 80 WAS coverage is required (at a minimum)
• Assuming a uniform distribution of targets
• This implies that minimum sensor range ? 100 nm
  for a single UAV WAS ConOps which drives the WAS
  sensor to operate at what altitude?
• Target ID, however, will be at 10Kft or less
• To meet the 80 visual ID requirement (weather)
• One option for reducing the mismatch is to go to
  a multi-UAV ConOps
• A four (4) UAV WAS ConOps would reduce the WAS
  range requirement to 50nm (at a minimum)
• A Sixteen (16) UAV WAS ConOps would reduce the
  range requirement to 25 nm

h(reqd) Rmax?Tan(?) 100nm?Tan(5?) 8.75 nm
53158 ft
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Bottom line

• We can design one (1) air vehicle or two (2)
• A one air vehicle type solution will be a
  compromise
• Cant optimize for both environments
• But only one development program, production
  line and support system will be required
• A two air vehicle type solution will require 2
  development programs, 2 production lines and 2
  support systems
• Cost will go through the roof
• We could do a trade study to determine which
  approach is most cost effective but historically
  a single, multi-capability design will be lower
  cost than 2 optimized single mission vehicles
• Therefore, we will try to find a single system
  design solution for both missions
• If that doesnt work, we can always fall back to
  the other option

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Intermission
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