Design of UAV Systems
Lesson objective - to discuss
Payloads
including …
• Sensors
• Weapons
• Example problem
Expectations - You will understand how to estimate
sensor size and performance and understand their
impact on overall system performance
c 2002 LM Corporation
Payloads
11-1
Design of UAV Systems
Importance
• UAV systems have little practical value
without payloads
- Including UCAVs
• A good understanding of payload design
issues and requirements are among the
most important issues addressed during
UAV pre-concept design
c 2002 LM Corporation
Payloads
11-2
Design of UAV Systems
UAV Payloads
http://www.fas.org/irp/program/collect/darkstar.htmadar
DarkStar
Primary Types :
Electro-Optical
Radar
Communications
TUAV
Predator
c 2002 LM Corporation
Modular Payloads Preferred
http://www.fas.org/irp/program/collect/tesar.htm
Payloads
11-3
Design of UAV Systems
c 2002 LM Corporation
Payloads
Integrated payloads
11-4
UCAV payloads
Design of UAV Systems
Air-to-Ground
Powered
Glide
UCAV payloads are not covered as a separate
subject. See RayAD Chapter 9.5 for overall
weapons integration issues and
www.fas.org/man/dod-101/sys/dumb/ for data
Small
Large
Very Small
LOCASS
http://www.fas.org/man/dod-101/sys/smart
c 2002 LM Corporation
Payloads
11-5
Design of UAV Systems
UCAV cont’d
Air-to-Air
Possible but not currently planned
c 2002 LM Corporation
Payloads
11-6
Design of UAV Systems
Sensor type(s)
• Wide area
• Spot
• Targeting
• Weather
effects
Weapon type(s)
• Unguided
• Platform guided
• Off board guided
• Self guided
Overall sizes
Aperture
requirements
Estimated cost
Power and cooling
requirements
c 2002 LM Corporation
Pre-concept design issues
Payloads
Note : There is no sensor cost data
available except for proprietary data
from manufacturers
11-7
Design of UAV Systems
Sensor resolution
Typically expressed in terms of National Interpretability
Rating Scale (NIIRS) or Ground Resolved Distance (GRD)
NIIRS
1
2
3
4
5
6
7
8
9
GRD (m)
Nominal capability (EO)
> 9.0
4.5 - 9.0
2.5 - 4.5
1.2 - 2.5
0.75 - 1.2
0.40 - 0.75
0.20 - 0.40
0.10 - 0.20
< 0.1
Detect medium sized port
Detect large buildings
Detect trains on tracks
Identify railroad tracks
Identify theater ballistic missile
Identify spare tire on truck
Identify individual rail ties
Identify windshield wiper
Identify individual rail spikes
For more information see http://www.fas.org/irp/imint/niirs.htm
c 2002 LM Corporation
Payloads
11-8
Resolution cont’d
Design of UAV Systems
2
c 2002 LM Corporation
3
4
Payloads
5
6
7
8
11-9
Design of UAV Systems
Sensor notation - overall
Field of regard (azimuth)
Field of view
(azimuth)
Angular resolution (miliradians)
Field of view (elevation)
Target resolution (meters)
Target range
c 2002 LM Corporation
Payloads
11-10
Design of UAV Systems
E0/IR sensors
• These cover a range of sensor types from simple
TV cameras to sophisticated thermal imaging
systems with large focal lengths and zoom range
• All are line of sight systems and typically do not
work well in weather
• Despite their weather limitations, EO/IR systems
are often preferred because of their high
resolution and ease of interpretation
- Even “thermal imagery” is easy to interpret by
untrained users
• EO/IR sensors are often mounted in gimbaled
“turrets” or balls which protrude into the slip
stream
• Some have integrated lasers for range
measurement and/or target designation
c 2002 LM Corporation
Payloads
11-11
Design of UAV Systems
Global Hawk Program Update, Kennon Cooksey, Deputy Director, 2/28/2001
c 2002 LM Corporation
Payloads
11-12
Design of UAV Systems
Global Hawk Program Update, Kennon Cooksey, Deputy Director, 2/28/2001
c 2002 LM Corporation
Payloads
11-13
Design of UAV Systems
EO/IR notation - nonscanning
Line of flight field of view (LFOV)
Field of regard
Single frame - near
Single frame - far
L-swath
Min slant range (Rn)

W-swath
Max slant range (Rf)

h

Slant range - near
mechanical limit
c 2002 LM Corporation
Slant range - far
function(resolution)
Cross flight field of view (XFOV)
Payloads
11-14
EO/IR notation - scanning
Design of UAV Systems
Line of flight field of view (LFOV)
Field of regard
Single frame - near
Single frame - far
Lswath
Single scan -near
Single scan -far
Min slant range (Rn)
Wswath

min

h
Max slant range (Rf)
Max slant range (Rf)
= function (resolution)
R
Min slant range (Rn)
= function(scan time)
c 2002 LM Corporation
Cross flight field of view (XFOV)
Payloads
11-13
Basic equations - EO/IR*
Design of UAV Systems
d = 2Pixel pitch (Pp)
h(alt) TECHNOLOGY DRIVERS
Scan rate (SR) in frames/sec
Pixel pitch (Pp) in mm
Typical EO = 5-10 
Typical IR = 25 
Np = Number of pixels per side
Stabilization (mrad)
OPERATIONAL DRIVERS
Resolution required (GRD or
NIIRS)
Target coverage rate (sqkm/hr)
c 2002 LM Corporation
Hfp = 2EFLTan[FOV/2] = PpNp
Inflight resolution(IFR) = KD/[d] (cycles/mm) = 1/d’
where KD (EO) ≈ 0.8; KD (IR) ≈ 0.9
d’/EFL = GRD’/R or R = GRD’EFLIFR
min = ArcSin(h/Rf)
Nonscanning EO/IR:  =  + FOV
Scanning EO/IR:  =  + SR*t ( > min )
where t = KolLswath/V (Kol < 1 for overlap)
Rn = h/Sin()
Wswath = 2RTan[FOV/2]
SS coverage = WswathLswath
where SS = single scan
Coverage rate = WswathV
Payloads
GRD’ = GRDSin()

GRD
*Courtesy of Mike I “Indiana” Jones, LM Aero
11-16
Design of UAV Systems
EO/IR example
From Janes UAVs and Targets (USA:Payload)
h = 65Kft = 19.811 Km; V = 343 kts = 176.45 mps
FOV (spot) = 5.1 x 5.2 mrad (0.292 x 0.298 deg)
EFL = 1.75 m
GRD @ 28Km = NIIRS 6.5 (EO) ≈ 0.44 m
Pixel pitch = 9, Pixel array = 1024 x 1024
Frame rate = 30 fps
Hfp = 10240.000009m = 9.22 mm
IFR = 28000/[1.750.440.707] = 51.43 cy/mm
Theoretical IFR = 1/[20.009] = 55.55
KD = 51.43 /55.55 = 0.93
min = ArcSin(h/Rf) = 45 deg
Lswath = 228sin(2.6mrad) = 0.146 Km
t = 146m/176.45mps = 0.827sec
Scans = 0.827s30fps = 24.82 frames
Assume Kol = 0.9
 = 45 + 24.820.2920.9 = 51.52 deg
Rn = 19.811 km/Sin(51.52) = 25.36 Km
Reasons for difference
not clear
Wswath = 19.811- 25.36*Cos(51.52) = 4.0 Km
c 2002 LM Corporation
Payloads
11-17
Typical EO/IR sensor
Design of UAV Systems
• Dual Sensor (IR / daylight)
- 3rd gen InSb (3-5 ?m)
> Three (3) FOV Optics
> 256 x 256 Staring FPA
- Daylight color camera with 10X
zoom lens
• 4-Axis Active Gyro- Stabilization
• 6-Axis Passive Vibration Isolation
• Power: 210 [W]
• Turret
- Diameter = 12 [in] (30.5 [cm])
- Height = 14.6 [in] (37 [cm])
- Weight = 47 [lbs]
• Electronics Unit
- None
• Air Vehicle Mounting Unit
- Platform Specific
• Interface
- Discrete / Analog
(Pioneer UAV) or RS-422
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Payloads
11-18
Design of UAV Systems
E0/IR example
DESCRIPTION
• Dual Sensor (3-5 micron FLIR & Color TV)
• IR camera 640 x 480 InSb Focal Plane Array
• 3 FOV optics
• Color TV single chip CCD
• Zoom lens matched to FLIR
• Digital video
• 4-Axis Gimbal based on Wescam stabilization technology
• Power: +28 volts, 4 amps avg, 10 amps peak, 300 watts (peak)
• Turret:
• Diameter = 11 inches
• Height = 15.5 inches w/mods
• Weight = 46 pounds
• Mission Interface Unit required
• Interface: IEEE 1394 or RS-422
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Sensors
11-19
Design of UAV Systems
E0/IR example
DESCRIPTION
• 3-Axis Stabilization
• IR detector assembly is a 3-5µm Indium Antinomide
• EO/IR/LRF/LI/Spotter Scope payloads available
• Turret Dimensions: 15.1”x 17.55”
• Weight: 92lbs
• Power: MIL-STD-704D 28VDC, 360W max.
• Interfaces:
- NTSC/PAL (Video)/RS 170
- 9600 Baud/RS 232/422
- Optional/1553B
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Sensors
11-20
E0/IR example
Design of UAV Systems
DESCRIPTION
• IR detector assembly is a 3-5µm Indium Antinomide
• EO/IR payloads standard
• Turret Dimensions: 9”x 13.5”
• Turret Weight: 26 lbs (total system weight less than 40 lbs)
• 2-Axis, 3 Fiber-Optic gyro Stabilization
• Power: 28VDC
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Sensors
11-21
Design of UAV Systems
E0/IR example
DESCRIPTION
• 2-Axis, 3 Fiber-Optic gyro Stabilization
• IR detector assembly is a 3-5µm Indium Antinomide
• EO/IR payloads standard
• 1.8X Optical IR extender, Low-light monochrome TV or Laser
Rangefinder optional
Turret Dimensions: 9”x 15.2”
Turret Weight: 26 lbs (total system weight less than 42 lbs)
Power: 28VDC
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Sensors
11-22
Design of UAV Systems
E0/IR example
DESCRIPTION
• 2-Axis, 3 Fiber-Optic gyro Stabilization
• IR detector assembly is a 3-5µm Indium Antinomide
• EO/IR payloads standard
• Turret Dimensions: 9”x 13.5”
• Turret Weight: 26 lbs (total system weight less than 40 lbs)
• Power: 28VDC, 450 Watts
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Sensors
11-23
IR/Laser example
Design of UAV Systems
• Combined IR sensor plus laser
(LRD)
- 2ND gen FLIR sensor w/ LAP, 3
FOVs, 2X & 4X electronic zoom ,
and digital video interface
- Laser Rangefinder Designator (LRD)
- Dual-mode automatic video tracker
- Integrated line-of-sight targeting
modes (including HELLFIRE)
- Imbedded maintenance &
alignment features
• Airborne System
- Weight < 165 [lbs]
- Power
- 28 VDC:Nominal 200W
- 115 VAC 3 Phase: Nominal 0.9
KVA
• Turret
- Diameter = 16.7 [in]
(15[in] at base)
- Height = 18.6 [in]
- Weight = 114 [lbs]
• Electronics Unit
- Height = 9.25 [in]\
- Width = 13.5 [in]
- Length = 14.75 [in] (incl handles)
- Weight = 48 [lbs]
• Interface(s):
- MIL-STD-1553 data buses
- Discrete / Analog I/O
- RS-170 analog video output
- Digital video output
- Symbology output
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Sensors
11-24
E0/IR/Laser example
Design of UAV Systems
• Combined 3 Sensors EO/IR/DPAD
• 4-Axis Stabilization (Option for IMU)
• In-flight Boresight Mechanism
• A Zoom Optics CCD Day TV
• Electronic Image Stabilization
• Dual Mode automatic Video Tracker
• IR detector is a 3-5µm InSb FPA (256 x 256 pixels)
• MOSP Payload Family includes:
- H-MOSP - For Helicopters
- SEA-MOSP: For Shipboard Operation
Dimensions:
Turret
Electronic Box (FEB)
15.0”dia x 19.6”H
70.5 lbs
Payload Control Logic (PCL)
9.6”H x 10.7”W x 4.7”L
12.1 lbs
10.4”H x 10.9”W x 10.6”L
23.3 lbs
Average Power: 28 VDC
With DPAD: Average 450W, Max 500W
w/o DPAD: Average 310W, Max 420W
Interfaces:
- Video/RS 170
- Serial Comm/RS 422
c 2002 LM Corporation
Sensors
FLIR
http://uav.navair.navy.mil/database/matrix.htm
11-25
Design of UAV Systems
E0/IR/Laser example
DESCRIPTION
• Combined IR/EO/Laser Designator/Eyesafe Laser Range Finder
• 4-Axis Stabilization, <20 µrad RMS
• 3-5µm Indium Antimonide IR detector, with CO2 Notch Filter
• High-resolution CCD TV, matched FOVs to IR
• Integrated Boresight Module
• Turret Dimensions: 16.1” D X 19.3” H
• Weight: 113lbs
• Power: MIL-STD-704D, 800W max. @ 28VDC
• Qualifications: MIL-STD-810E and –461D
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Sensors
11-26
Design of UAV Systems
E0/IR/Laser example
DESCRIPTION
• RISTA is derived from the Army’s Airborne Standoff Minefield
Detection System (ASTAMIDS) program
• There are two modes of operation: spotlight and line scanning w/
either mode selectable during flight from the image processing facility (IPF).
• Utilizes a 2nd generation IR
• Volume: <4900in3 for airborne LRUs
• Weight: <145lbs for airborne LRUs
<84lbs for ground processor.
• Power: 700W avg., 1000W pk.
• Cooling: External Ambient Air
• Interfaces:
- Video/Rs 170
- RS 232/485
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Sensors
11-27
Design of UAV Systems
E0/IR/Laser example
DESCRIPTION
• 3-Axis Stabilization
• IR detector assembly is 8-12µm 4X4 MCT w/TDI
• EO/IR/LRF/LI payloads available
• Turret Dimensions: 15.1”x 17.55”
• Weight: 88lbs (w/CCD or LRF)
• Power: MIL-STD-704D 28VDC, 360W max
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Sensors
11-28
Design of UAV Systems
E0/IR/Laser example
DESCRIPTION
• Combined EO/IR/LD/LRF (with eye safe modes)/Tracker
• Options: LST and Low light CCD
• 20.5 in. Diameter Turret / 24 in. height
• Target Weight
- RFI = 206 & AH-1Z = 277
• Power: 1.6 kW
• Interfaces:
- RS 422
- IEEE 1394
• Internal Volume: 1 ft3
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Payloads
11-29
Design of UAV Systems
c 2002 LM Corporation
Payloads
Global Hawk EO/IR
11-30
E0/IR sizing
Design of UAV Systems
“Small” UAVs
≈ 50 ppcf
Global Hawk EO/IR Sensor
≈ 14 ppcf
c 2002 LM Corporation
Payloads
11-31
Design of UAV Systems
RF sensors
• These cover a range of sensor types from simple
airborne weather radar to sophisticated multi-mode
electronically scanned radar systems
• The two most widely used are synthetic aperture
radar (SAR) and moving target indicators (MTI) and
combinations thereof (SAR/MTI)
• RF sensors are generally considered “all weather”
systems but their performance can be significantly
degraded by rain or moisture
• One disadvantage of RF sensors is the
interpretability of their “imagery”
- A SAR “image” may look like a picture but it isn’t
- Shadowing, scattering and multipath are problems
• Most RF antennae scan mechanically, more
modern (and expensive) ones scan electronically
c 2002 LM Corporation
Payloads
11-32
Design of UAV Systems
Global Hawk Program Update, Kennon Cooksey, Deputy Director, 2/28/2001
c 2002 LM Corporation
Payloads
11-33
Sensor notation - SAR
Design of UAV Systems
Spot mode long dwell time
Squint angle < 60 deg
Field of regard
L-swath
W-swath
Wide area search mode
- near real time
Min range
Max range

h

Slant range - max
Slant range - min

c 2002 LM Corporation
Payloads
11-34
Design of UAV Systems
Straight line coverage
Area = SwathSpeedTime
Search distance = Area/Swath
c 2002 LM Corporation
Payloads
Wide area coverage
Search pattern coverage
KArea = SwathSpeedTime
= SwathLEDRFcr/RFlo
Typical factor (K) = 1.3?
11-35
Design of UAV Systems
Spot area coverage
GH example -1900 spots per day
Average dwell time = 24*3600/1900
= 45.5 sec/spot
Spot area coverage = 1900*4
= 7600 sqkm/day
vs. 138,000 sqkm/day search
(4/98)
Graphic from page 54 (grid added)
c 2002 LM Corporation
Payloads
11-36
Design of UAV Systems
Predator SAR
http://www.fas.org/irp/program/collect/tesar.htm
c 2002 LM Corporation
Payloads
11-37
Design of UAV Systems
Predator cont’d
http://www.fas.org/irp/program/collect/tesar.htm
c 2002 LM Corporation
Payloads
11-38
Predator radar
Design of UAV Systems
DESCRIPTION
• Operates in SAR and MTI modes
• Coordinates of each map center are provided within 25 meters CEP
• Provides for operation in a strip, and spot map modes MTBF >900hrs
Performance/Specifications
Hardware
RF Frequency
Weight
Power
Volume
Cooling
MTBF
Ground Speed
Altitude
Ku-Band
74.9kg/165lbs
1050W
0.12 m3/4.15ft3
Ambient Air
>900hrs
50-90 kts
7620m/25,000ft
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Sensors
11-39
Other SAR
Design of UAV Systems
• Antenna Assembly
A Lightweight, High Performance SAR,
- 19 in. diameter radome
Designed and Built for UAV Platforms
- Reflector antenna
- Two stripmap or search modes
- Three-axis gimbal
- Spotlight Mode
- Motion measurement
- Ground moving target indicator
hardware (IMU & GPS)
(GMTI)
- 320 W TWT
- Coherent change detection (CCD)
- LNA
- Ku band operation
• Radar Electronics Assembly
- 0.3 m resolution in stripmap mode
- Height = 10.75 [in]
- 0.1 m resolution in spotlight mode
- Width = 14.88 [in]
- 30 km range in weather (0.3 res)
- Length = 21.5 [in]
- Weight < 115 [lbs]
- VME chassis - slots available
- Power < 1200 W total
• Interface(s):
• Digital imagery output available in
- NTSC video link/RS 170
NITF format and NATO standard
- Digital data link for full
format
resolution/RS485
• Power
GA-ASI ground control
- 500 Watts
station link
• Data Transfer Rates
- Spotlight Mode/3.2 mbsec
- Strip mode/ 10m
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Sensors
11-40
More SAR
Design of UAV Systems
DESCRIPTION
• Uses heritage from all of Europe’s space SAR projects (ERS-1, ERS-2, ASAR).
• Provides a modular, flexible and expandable payload system for all types of
UAV w/ a payload capacity of greater than 35kg.
• Capable of multi-payload control.
• Can be adapted to use at L, C, X, or Ku-Band operation
Parameter
RADAR Frequency
Bandwidth
TX. Power
Min PRF
Max PRF
Antenna Length
Antenna Height
Value
9650
270
200
275
6500
41
21
Units
MHz
MHz
W
Hz
Hz
cm
cm
Parameter
Controller
RF Equipment
Power Conditioner
Transmit Amplifier
Receive Antenna
Antenna
Antenna Platform
Harness
Mass (kg)
15
6
2
1
0.1
1
10.1
1
DC Powe r (W)
121
52
31
2
2
0
31
0
c 2002 LM Corporation
Sensors
http://uav.navair.navy.mil/database/matrix.htm
11-41
Design of UAV Systems
c 2002 LM Corporation
Payloads
Global Hawk SAR/MTI
11-42
TUAV SAR/MTI
Design of UAV Systems
DESCRIPTION
• Unit will provide both SAR and MTI modes.
• SAR mode provides both strip map and spot images at resolutions from
0.1 to 1.0 meters at ranges from 3 to 12 km.
• MTI mode will detect a 10m2 target at 14 km with a PD of 0.75
• False alarm rate less than 2 per minute in 4mm/hr rain.
• Weight: 63 lbs
Interfaces:
-RS 422
• Power: Surge - System Start up with fans and all electronics powering
up: 616 W
Constant - All systems operating except transmitter 380W
Peak - All systems operating and transmitting: 476W
NOTES
• Unit is being developed for the US Army.
• SAR is designed to be low cost with predicted recurring cost per
payload (for the 10th unit in a lot of 10) is less than $500 K?
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Payloads
11-43
Design of UAV Systems
Multimode radar example
DESCRIPTION
• SeaVue Has Nine Operating Modes:
Standby, Test, Search1, Search2, Weather, ISAR, SAR, DBS, MTI
• Hardware:
- Rcv_Exc_Sync_Processor
- Transmitter (X-Band)
- Antenna System Weight: 200-lbs.
• Platforms:
- Helicopters
- Large & Small MPA
- Ships
- Land Based
Maritime Surveillance & Tracking
• ASuW, OTH-T, ASST
• Search and Rescue Ship and
Overland Imaging
• Activity Detection
http://uav.navair.navy.mil/database/matrix.htm
c 2002 LM Corporation
Sensors
11-44
Design of UAV Systems
RF sensor sizing
≈ 40 ppcf
Global Hawk
≈ 43 ppcf
c 2002 LM Corporation
Payloads
11-45
Design of UAV Systems
Sensor bandwidth
SAR image at expanded scale
showing pixel detail and gray
scale level
Example - Global hawk SAR imaging data
Sensor bandwidth requirements trace directly to
sensor coverage requirements per unit time
c 2002 LM Corporation
Payloads
11-46
Design of UAV Systems
Bandwidth calculation
• Global Hawk SAR example - 138,000 sqkm/day area
search area at 1m resolution (from Lesson 9)
138,000 km^2/day @ 1m resolution =
(138000 sqkm)*(10^6 sqm/sqkm)/(24*3600 sec/day)
= 1,597,222 resolution cells per second
- At an 8 level gray scale, 1 resolution cell requires 8
bits of data or 12.8 Mbps
- With 4:1 compression, data rate reduces to 3.2 Mbps
• Spot image example - 1900, 0.3 m resolution 2 Km x 2
Km SAP spot images per day, an equivalent data rate of
2.0 Mbps
• Ground moving target indicator (GMTI) example search rate of 15,000 sq. Km/min at 10 m resolution, an
implied bandwidth of about 5Mbps
c 2002 LM Corporation
Payloads
11-47
Design of UAV Systems
Expectations
You should now understand
•
•
•
•
•
Basic sensor types
System design and operational considerations
Basic sizing considerations
Sensor bandwidth requirements
How to make an initial estimate of size, weight
and power
• Where to go for more information
•
c 2002 LM Corporation
Sensors
11-48
Example problem
Design of UAV Systems
• Five medium UAVs, four provide wide area search, a
fifth provides positive target identification
- WAS range required (95km) not a challenge
• Only one UAV responds to target ID requests
• No need to switch roles, simplifies ConOps
• No need for frequent climbs and descents
• Communications distances
reasonable (158nm & 212 nm)
27.4 Kft
• Speed requirement = 280 kts
• Air vehicle operating altitude
212 nm
differences reasonable
• What sensors are
required?
• How big are they and
how much power is
required?
c 2002 LM Corporation
Sensors
158 nm
27.4 Kft 10 Kft
27.4 Kft
100 nm
200 nm x 200 nm
11-49
Design of UAV Systems
“Project” sensors
SAR (Ground moving target indication = GMTI,
Wide area search = WAS, Spot mode = Spot)
• Long range (Spot-WAS-GMTI)
• 0.3-1.0-10m resolution @ 20-200 Km, 6400W, 640 lbm
• Medium range (Spot-WAS -GMTI)
• 0.2-1m -10m resolution @ 5-50 Km, 1160W, 168 lbm
• Short range (Spot-WAS -GMTI)
• 0.1-1m -10m resolution @ 3-12 Km, 476W, 63 lbm
EO/IR
• Global Hawk Scanning Type (Spot-WAS)
• 0.5-0.75m resolution @ 28 Km, 582W, 220 lbm
• Turret Type I @ 12”D (Spot-WAS)
• 0.15m-3.2m resolution @ 3-8 Km, 300W, 50 lbm
• Turret Type II @ 15”D (Spot-WAS)
• 0.3-0.64m resolution @ 8 Km, 700W, 100 lbm
See – ASE261.ProjectSensors.xls
c 2002 LM Corporation
Sensors
11-50
Design of UAV Systems
Search considerations - review
• If a UAV loiters over a fixed point in the middle of a
square surveillance area, it can meet the 80%
coverage, 2 minute moving target detection wide area
surveillance (WAS) requirements if
1. It makes a turn every 2 minutes (assuming a nominal
45 degree SAR field of regard)
- And the image processing
Target
plus transmit time is held to
30 seconds or less
Target
2. The SAR range is slightly
larger than ½ the width of the
101 nm
surveillance area
Min range
- Area of circlesquare = /4
effects ignored
= 0.785
3. It has a 100% detection rate
200 nm x 200 nm
c 2002 LM Corporation
Sensors
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Design of UAV Systems
Min range coverage effect
Nominal min = 5
Nominal max = 60
Nominal FOR = 45
Therefore, nominal GMTI Area :
= (/4)[Rmax^2-Rmin^2] =
= (/4)(Rmax^2){1-[Tan()/Tan()]^2}
 0.997(/4)(Rmax^2)
Bottom line – don’t worry
about the min range GMTI
hole under the platform


Rmin = RmaxTan()/Tan()
Rmax
hmin =
RmaxTan()

c 2002 LM Corporation
Sensors
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Design of UAV Systems
SAR sizing considerations
A number of factors affect SAR range (minimum and
maximum) and resolution
- Power (how much RF energy is reflected from the target)
- Even though transmitted power required vs. radar
range is typically expressed as a 4th power
relationship, our parametric data (based on total input
power required) shows a nominal linear relationship
- Geometry (minimum and maximum depression angles)
- Absolute minimum angle defined by the radar horizon
- Typical minimum “look down” angle  5-10 degrees
- Typical maximum “look down” angle about 60 degrees
- Dwell time (how long energy stays on the target)
- Function of platform speed and/or antennae pointing
- Signal processing time
To keep things simple, we resize using only the rangepower parametric and geometry (ignoring curvature)
c 2002 LM Corporation
Sensors
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SAR geometry
Design of UAV Systems
Long Range SAR Profile
70
Altitude (Kft)
60
5 deg
Note - earth
curvature
effects have
been ignored
50
40
44.7 deg
30
20
20.8 deg
10
5.6 deg
0
0
100
Min range
(from spreadsheet)
200
Range (km)
300
Max range
(from spreadsheet)
This project SAR is operating near the limit of minimum
acceptable grazing angle
• Max range grazing angle = 5.7 vs. minimum 5 degrees
c 2002 LM Corporation
Sensors
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SAR geometry (cont’d)
Design of UAV Systems
Other SAR Profiles
Altitude (Kft)
30
Medium Range SAR
Short Range SAR
8.7 deg
This plot also
ignores earth
curvature effects
20
20.8 deg
10
Max range at 5
degree lookdown
= 52 - 87 km
17 –27 deg
0
0
25
50
75
Range (km)
With additional power these SARs could increase WAS
range to 52 - 87 Km
• After that increased altitude search altitude is required
c 2002 LM Corporation
Sensors
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Design of UAV Systems
Positive ID considerations
• 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 operate at or below 10 Kft for 30%
of the target identifications
• 50% of the time we can stay at altitude and 20% of the
time we won’t see a target (unless we image at <= 5 Kft)
• This places 10Kft efficient cruise, loiter and climb and
descent rate requirements on the air vehicle
Atmospheric conditions (customer defined)
Cloud ceiling/visibility Percent occurrence
50%
Clear day, unrestricted
30%
10Kft ceiling, 10 nm
15%
5Kft ceiling, 5 nm
05%
1Kft ceiling, 1nm
c 2002 LM Corporation
Sensors
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Design of UAV Systems
Sensor payloads
• Some but not all wide area search, ground moving
target requirements can be satisfied by spreadsheet
ASE261.Project Sensors.xls medium range SAR
• Weight = 168 lbm
• Resolution = 10m
95km req’d
• Volume = 4.15 cuft
• Range = 50km
• Power req’d = 1160 W • Field of regard =  45
• We solve the problem by using parametric data to
resize the SAR
• Power req’d = 3000 W
We assume resolution and
• Weight = 350 lbm
field of regard are unchanged
• Volume = 8 cuft
• The under weather, target identification requirement
is satisfied by EO/IR turret type 2
• GRD = 0.3 @ 8 km
Or = 0.5m at 13.3 km
• Diameter = 15 in
(from basic optics)
• Weight = 100 lbm
•Power req’d = 700 W
• Volume = 1 cuft
c 2002 LM Corporation
Sensors
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Design of UAV Systems
Installation considerations
• All systems on an air vehicle have installation weight
and volume penalties (to be covered in detail later)
• We will assume typical installation at 130% of dry
uninstalled weight
• We will make this assumption for all installed items
(mechanical systems, avionics, engines, etc.)
• Installed volume is estimated by allowing space
around periphery, assume 10% on each dimension
• Installed volume = 1.33 uninstalled volume
• For frequently removed items or those requiring air
cooling, we will add 25%
• Installed volume = 1.95 uninstalled volume
• Our payloads and data links will be installed this way
• Installed weights and volumes as follows:
Total = 720 lbm
• EO/IR = 130 lbm @ 1.95 cuft
@ 26.55 cuft
• SAR = 455 lbm @ 15.6 cuft
• Communications (each) = 67.5 lbm @ 4.5 cuft
c 2002 LM Corporation
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Design of UAV Systems
Requirement summary
• It is important to maintain an up to date list of
requirements as they are defined or developed
1 ID PER HR
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 image of spot targets
(goal = 100%, threshold = 80%) in 15 min.
• Operate from base with 3000ft paved runway
Atmospheric conditions (customer defined)
Cloud ceiling/visibility
Percent occurrence
Clear day, unrestricted
10Kft ceiling, 10 nm
5Kft ceiling, 5 nm
1Kft ceiling, 1nm
50%
30%
15%
05%
c 2002 LM Corporation
Sensors
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Design of UAV Systems
Derived requirements
Derived requirements (from our assumptions or studies)
• System element
• Maintain continuous WAS/GMTI coverage at all times
• One target recognition assignment at a time
• 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 – 27.4Kft
• Loiter location = 158 nm (min) – 255 nm (max)
• Loiter pattern – 2 minute turn
• Dash performance =141 nm @ 282 kts @10 Kft
• Payload weight and volume = 720 lbm @ 26.55 cuft
• Payload power required = 4700 W
c 2002 LM Corporation
Sensors
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Design of UAV Systems
Derived requirements
• Payload element
• Installed weight/volume/power  720lbm/26.55 cuft/4700W
• SAR/GMTI
• Range/FOR /resolution/speed = 95 km/45/10m/2mps
• Uninstalled weight/volume/power  350lbm/8cuft/3000W
• EO/IR
• Type/range/resolution = Turret/13.3 km/0.5m
• Uninstalled weight/volume/power  100lbm/1cuft/700W
• Communications
• Range/type = 212nm/air vehicle and payload C2I
• Uninstalled weight/volume/power  52lbm/2.3cuft/500W
• Range/type = 158nm/communication relay
• Uninstalled weight/volume/power  52lbm/2.3cuft/500W
c 2002 LM Corporation
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Design of UAV Systems
Reading assignment
Raymer, Aircraft Design - A Conceptual Approach
Chapter 18 - Cost analysis
•
•
•
•
•
•
Chapter 18.1 : Introduction
Chapter 18.2 : Life cycle cost
Chapter 18.3 : Cost estimating methods
Chapter 18.4 : RDT&E and production costs
Chapter 18.5 : Operations and maintenance costs
Chapter 18.6 : Cost measures of merit
Total : 15 pages
Note - Raymer is a reference book. It is not
necessary to memorize or derive any of the
equations. Read the sections over for general
understanding of the concepts.
c 2002 LM Corporation
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Design of UAV Systems
Homework
Assess sensor requirements for your project and
define a sensor suite that you think will work
(1) Size a sensor suite that meets requirements
- Uninstalled weight, volume and power
(2) Calculate installed weights and volumes.
- Use nominal installation factors
(3) Calculate total weight & volume power required
(4) Document your derived requirements
Submit your homework via Email to Egbert by
COB next Thursday. Document all calculations
c 2002 LM Corporation
Sensors
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Design of UAV Systems
c 2002 LM Corporation
Sensors
Intermission
11-64