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11-1
Design of UAV Systems
Payloadsc 2002 LM Corporation
Lesson objective - to discuss
Payloadsincluding …
• Sensors
• Weapons• Example problem
Expectations - You will understand how to estimate sensor size and performance and understand their impact on overall system performance
11-2
Design of UAV Systems
Payloadsc 2002 LM Corporation
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
11-3
Design of UAV Systems
Payloadsc 2002 LM Corporation
UAV Payloads
Primary Types :Electro-OpticalRadarCommunications
http://www.fas.org/irp/program/collect/darkstar.htmadar
TUAV
DarkStar
http://www.fas.org/irp/program/collect/tesar.htm PredatorModular Payloads Preferred
11-4
Design of UAV Systems
Payloadsc 2002 LM Corporation
Integrated payloads
11-5
Design of UAV Systems
Payloadsc 2002 LM Corporation
UCAV payloads
http://www.fas.org/man/dod-101/sys/smart
Powered
JSOW
Small
Large
Very Small LOCASS
Air-to-Ground
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
11-6
Design of UAV Systems
Payloadsc 2002 LM Corporation
UCAV cont’d
Air-to-Air
Possible but not currently planned
11-7
Design of UAV Systems
Payloadsc 2002 LM Corporation
Pre-concept design issues
Power and cooling requirements
Overall sizes
Estimated cost
Sensor type(s)• Wide area• Spot• Targeting• Weather effects
Aperture requirements
Weapon type(s)• Unguided• Platform guided• Off board guided• Self guided
Note : There is no sensor cost data available except for proprietary data from manufacturers
11-8
Design of UAV Systems
Payloadsc 2002 LM Corporation
Sensor resolution
Typically expressed in terms of National Interpretability Rating Scale (NIIRS) or Ground Resolved Distance (GRD)
For more information see http://www.fas.org/irp/imint/niirs.htm
NIIRS GRD (m) Nominal capability (EO)
1 > 9.0 Detect medium sized port 2 4.5 - 9.0 Detect large buildings 3 2.5 - 4.5 Detect trains on tracks 4 1.2 - 2.5 Identify railroad tracks 5 0.75 - 1.2 Identify theater ballistic missile 6 0.40 - 0.75 Identify spare tire on truck 7 0.20 - 0.40 Identify individual rail ties 8 0.10 - 0.20 Identify windshield wiper 9 < 0.1 Identify individual rail spikes
Design of UAV Systems
Payloadsc 2002 LM Corporation
Resolution cont’d
Sensor resolution
0
1
2
3
4
5
6
7
8
9
2 3 4 5 6 7 8 9
NIIRS
2 3 4 5 6 7 8
11-9
Design of UAV Systems
Payloadsc 2002 LM Corporation
Sensor notation - overall
Field of regard (azimuth)
Field of view(azimuth)
Field of view (elevation)
Angular resolution (miliradians)
Target resolution (meters)
Slant range
Target range
11-10
Design of UAV Systems
Payloadsc 2002 LM Corporation
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
11-11
Design of UAV Systems
Payloadsc 2002 LM Corporation 11-12
Global Hawk Program Update, Kennon Cooksey, Deputy Director, 2/28/2001
Design of UAV Systems
Payloadsc 2002 LM Corporation 11-13
Global Hawk Program Update, Kennon Cooksey, Deputy Director, 2/28/2001
Design of UAV Systems
Payloadsc 2002 LM Corporation
EO/IR notation - nonscanning
Field of regard
Line of flight field of view (LFOV)
Max slant range (Rf)Min slant range (Rn)
Single frame - farSingle frame - near
W-swath
L-swath
h
Slant range - nearmechanical limit
Slant range - farfunction(resolution)
Cross flight field of view (XFOV)
11-14
Design of UAV Systems
Payloadsc 2002 LM Corporation
Field of regard
Line of flight field of view (LFOV)
Max slant range (Rf)
Min slant range (Rn)
Single scan -farSingle scan -near
Single frame - farSingle frame - near
Wswath
Lswath
h
Min slant range (Rn)= function(scan time)
Max slant range (Rf)= function (resolution)
min
Cross flight field of view (XFOV)
EO/IR notation - scanning
11-13
R
Hfp = 2EFLTan[FOV/2] = PpNpInflight resolution(IFR) = KD/[d] (cycles/mm) = 1/d’
where KD (EO) ≈ 0.8; KD (IR) ≈ 0.9d’/EFL = GRD’/R or R = GRD’EFLIFRmin = ArcSin(h/Rf)Nonscanning EO/IR: = + FOV Scanning EO/IR: = + SR*t ( > min )
where t = KolLswath/V (Kol < 1 for overlap) Rn = h/Sin()
Wswath = 2RTan[FOV/2] SS coverage = WswathLswath
where SS = single scanCoverage rate = WswathV
Design of UAV Systems
Payloadsc 2002 LM Corporation
Basic equations - EO/IR*
TECHNOLOGY DRIVERSScan rate (SR) in frames/secPixel pitch (Pp) in mm
Typical EO = 5-10 Typical IR = 25
Np = Number of pixels per sideStabilization (mrad)
OPERATIONAL DRIVERSResolution required (GRD or NIIRS)Target coverage rate (sqkm/hr) *Courtesy of Mike I “Indiana” Jones, LM Aero
Max range (Rf)
FOV
Equiv focallength (EFL)
GRD
GRD’ = GRDSin()
11-16
d = 2Pixel pitch (Pp)H
fp
h(alt)
Design of UAV Systems
Payloadsc 2002 LM Corporation
EO/IR example
From Janes UAVs and Targets (USA:Payload)
h = 65Kft = 19.811 Km; V = 343 kts = 176.45 mpsFOV (spot) = 5.1 x 5.2 mrad (0.292 x 0.298 deg)EFL = 1.75 mGRD @ 28Km = NIIRS 6.5 (EO) ≈ 0.44 mPixel pitch = 9, Pixel array = 1024 x 1024Frame rate = 30 fps
Hfp = 10240.000009m = 9.22 mmIFR = 28000/[1.750.440.707] = 51.43 cy/mmTheoretical IFR = 1/[20.009] = 55.55KD = 51.43 /55.55 = 0.93min = ArcSin(h/Rf) = 45 degLswath = 228sin(2.6mrad) = 0.146 Kmt = 146m/176.45mps = 0.827secScans = 0.827s30fps = 24.82 framesAssume Kol = 0.9 = 45 + 24.820.2920.9 = 51.52 degRn = 19.811 km/Sin(51.52) = 25.36 Km
Wswath = 19.811- 25.36*Cos(51.52) = 4.0 Km
Reasons for difference not clear
11-17
Design of UAV Systems
Payloadsc 2002 LM Corporation
• 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
Typical EO/IR sensor
http://uav.navair.navy.mil/database/matrix.htm
11-18
11-19
Design of UAV Systems
Sensorsc 2002 LM Corporation
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
E0/IR example
http://uav.navair.navy.mil/database/matrix.htm
11-20
Design of UAV Systems
Sensorsc 2002 LM Corporation
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
E0/IR example
http://uav.navair.navy.mil/database/matrix.htm
11-21
Design of UAV Systems
Sensorsc 2002 LM Corporation
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
E0/IR example
http://uav.navair.navy.mil/database/matrix.htm
11-22
Design of UAV Systems
Sensorsc 2002 LM Corporation
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
E0/IR example
http://uav.navair.navy.mil/database/matrix.htm
11-23
Design of UAV Systems
Sensorsc 2002 LM Corporation
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
E0/IR example
http://uav.navair.navy.mil/database/matrix.htm
11-24
Design of UAV Systems
Sensorsc 2002 LM Corporation
• 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
IR/Laser example
http://uav.navair.navy.mil/database/matrix.htm
11-25
Design of UAV Systems
Sensorsc 2002 LM Corporation
• 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 Payload Control Logic (PCL) FLIR Electronic Box (FEB)15.0”dia x 19.6”H 9.6”H x 10.7”W x 4.7”L 10.4”H x 10.9”W x 10.6”L70.5 lbs 12.1 lbs 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
E0/IR/Laser example
http://uav.navair.navy.mil/database/matrix.htm
11-26
Design of UAV Systems
Sensorsc 2002 LM Corporation
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
E0/IR/Laser example
http://uav.navair.navy.mil/database/matrix.htm
11-27
Design of UAV Systems
Sensorsc 2002 LM Corporation
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
E0/IR/Laser example
http://uav.navair.navy.mil/database/matrix.htm
11-28
Design of UAV Systems
Sensorsc 2002 LM Corporation
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
E0/IR/Laser example
http://uav.navair.navy.mil/database/matrix.htm
Design of UAV Systems
Payloadsc 2002 LM Corporation
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
E0/IR/Laser example
http://uav.navair.navy.mil/database/matrix.htm
11-29
11-30
Design of UAV Systems
Payloadsc 2002 LM Corporation
Global Hawk EO/IR
11-31
Design of UAV Systems
Payloadsc 2002 LM Corporation
E0/IR sizing
EO/IR Power
0
400
800
1200
1600
5 10 15 20 25
Turret diameter (in)
Wa
tts (
pe
ak
)
EO/IR Turret size
10
15
20
25
5 10 15 20 25
Diameter (in)
He
igh
t (i
n)
EO/IR Weight
0
50
100
150
200
250
5 10 15 20 25
Turret diameter (in)
We
igh
t (l
b)
Global Hawk EO/IR Sensor
“Small” UAVs≈ 50 ppcf
≈ 14 ppcf
11-32
Design of UAV Systems
Payloadsc 2002 LM Corporation
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
11-33
Design of UAV Systems
Payloadsc 2002 LM Corporation
Global Hawk Program Update, Kennon Cooksey, Deputy Director, 2/28/2001
11-34
Design of UAV Systems
Payloadsc 2002 LM Corporation
Sensor notation - SAR
Field of regard
Max range
Min range
W-swath
L-swath
h Slant range - min Slant range - max
Wide area search mode- near real time
Squint angle < 60 degSpot mode - long dwell time
11-35
Design of UAV Systems
Payloadsc 2002 LM Corporation
Wide area coverage
Straight line coverageArea = SwathSpeedTime
Search distance = Area/Swath
Search pattern coverageKArea = SwathSpeedTime= SwathLEDRFcr/RFloTypical factor (K) = 1.3?
11-36
Design of UAV Systems
Payloadsc 2002 LM Corporation
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)
11-37
Design of UAV Systems
Payloadsc 2002 LM Corporation
http://www.fas.org/irp/program/collect/tesar.htm
Predator SAR
11-38
Design of UAV Systems
Payloadsc 2002 LM Corporation
http://www.fas.org/irp/program/collect/tesar.htm
Predator cont’d
11-39
Design of UAV Systems
Sensorsc 2002 LM Corporation
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 Ku-Band Weight 74.9kg/165lbs Power 1050W Volume 0.12 m3/4.15ft3 Cooling Ambient Air MTBF >900hrs Ground Speed 50-90 kts Altitude 7620m/25,000ft
Predator radar
http://uav.navair.navy.mil/database/matrix.htm
11-40
Design of UAV Systems
Sensorsc 2002 LM Corporation
A Lightweight, High Performance SAR, Designed and Built for UAV Platforms - Two stripmap or search modes - Spotlight Mode - Ground moving target indicator (GMTI) - Coherent change detection (CCD) - Ku band operation - 0.3 m resolution in stripmap mode - 0.1 m resolution in spotlight mode - 30 km range in weather (0.3 res) - Weight < 115 [lbs] - Power < 1200 W total • Digital imagery output available in NITF format and NATO standard format • Power - 500 Watts
• Antenna Assembly - 19 in. diameter radome - Reflector antenna - Three-axis gimbal - Motion measurement hardware (IMU & GPS) - 320 W TWT - LNA • Radar Electronics Assembly - Height = 10.75 [in] - Width = 14.88 [in] - Length = 21.5 [in] - VME chassis - slots available • Interface(s): - NTSC video link/RS 170 - Digital data link for full resolution/RS485 - GA-ASI ground control station link • Data Transfer Rates - Spotlight Mode/3.2 mbsec - Strip mode/ 10m
Other SAR
http://uav.navair.navy.mil/database/matrix.htm
Design of UAV Systems
Sensorsc 2002 LM Corporation
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 Value UnitsRADAR Frequency 9650 MHzBandwidth 270 MHzTX. Power 200 WMin PRF 275 HzMax PRF 6500 HzAntenna Length 41 cmAntenna Height 21 cm
Parameter Mass (kg) DC Powe r (W)Controller 15 121RF Equipment 6 52Power Conditioner 2 31Transmit Amplifier 1 2Receive Antenna 0.1 2Antenna 1 0Antenna Platform 10.1 31Harness 1 0
More SAR
http://uav.navair.navy.mil/database/matrix.htm
11-41
11-42
Design of UAV Systems
Payloadsc 2002 LM Corporation
Global Hawk SAR/MTI
11-43
Design of UAV Systems
Payloadsc 2002 LM Corporation
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
TUAV SAR/MTI
http://uav.navair.navy.mil/database/matrix.htm
K?
11-44
Design of UAV Systems
Sensorsc 2002 LM Corporation
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
Multimode radar example
http://uav.navair.navy.mil/database/matrix.htm
Design of UAV Systems
Payloadsc 2002 LM Corporation
RF sensor sizing
Global Hawk
UAV RF Sensors
0
150
300
450
600
750
0 3 6 9 12 15
Volume (cuft)
We
igh
t (l
bs)
SARMTI
UAV RF Sensors
0
1500
3000
4500
6000
0 150 300 450 600 750
Weight (lb)
Po
we
r (W
)
SARMTI
≈ 43 ppcf
≈ 40 ppcf
SAR sizing
0
2000
4000
6000
0 50 100 150 200
Max Range (km)
11-45
Design of UAV Systems
Payloadsc 2002 LM Corporation
Sensor bandwidth
Sensor bandwidth requirements trace directly to sensor coverage requirements per unit time
SAR image at expanded scale showing pixel detail and gray scale level
Example - Global hawk SAR imaging data
11-46
Design of UAV Systems
Payloadsc 2002 LM Corporation
• 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
Bandwidth calculation
11-47
11-48
ExpectationsDesign of UAV Systems
Sensorsc 2002 LM Corporation
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
11-49
Design of UAV Systems
Sensorsc 2002 LM Corporation
Example problem
• 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)
• Speed requirement = 280 kts • Air vehicle operating altitude differences reasonable • What sensors are required?• How big are they and how much power is required?
100 nm
200 nm x 200 nm
158 nm
27.4 Kft
10 Kft27.4 Kft 27.4 Kft
212 nm
11-50
Design of UAV Systems
Sensorsc 2002 LM Corporation
“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 lbmEO/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
11-51
Design of UAV Systems
Sensorsc 2002 LM Corporation
• 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 if1. It makes a turn every 2 minutes (assuming a nominal 45 degree SAR field of regard)
- And the image processing plus transmit time is held to 30 seconds or less
2. The SAR range is slightly larger than ½ the width of the surveillance area- Area of circlesquare = /4
= 0.7853. It has a 100% detection rate
Search considerations - review
Target
101 nm
200 nm x 200 nm
Target
Min range effects ignored
11-52
Design of UAV Systems
Sensorsc 2002 LM Corporation
Min range coverage effect
Rmin = RmaxTan()/Tan()
hmin =RmaxTan()
Nominal min = 5Nominal max = 60Nominal FOR = 45
Therefore, nominal GMTI Area := (/4)[Rmax^2-Rmin^2] == (/4)(Rmax^2){1-[Tan()/Tan()]^2} 0.997(/4)(Rmax^2)
Rmax
Bottom line – don’t worry about the min range GMTI hole under the platform
11-53
Design of UAV Systems
Sensorsc 2002 LM Corporation
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 timeTo keep things simple, we resize using only the range-power parametric and geometry (ignoring curvature)
11-54
Design of UAV Systems
Sensorsc 2002 LM Corporation
Long Range SAR Profile
0
10
20
30
40
50
60
70
0 100 200 300
Range (km)
Alt
itu
de
(Kft
)
5.6 deg
5 deg
Max range(from spreadsheet)
Min range(from spreadsheet)
44.7 deg
20.8 deg
SAR geometry
This project SAR is operating near the limit of minimum acceptable grazing angle• Max range grazing angle = 5.7 vs. minimum 5 degrees
Note - earth curvature effects have been ignored
11-55
Design of UAV Systems
Sensorsc 2002 LM Corporation
SAR geometry (cont’d)
With additional power these SARs could increase WAS range to 52 - 87 Km• After that increased altitude search altitude is required
Other SAR Profiles
0
10
20
30
0 25 50 75
Range (km)
Alt
itu
de
(Kft
)Medium Range SAR
Short Range SAR8.7 deg
20.8 degMax range at 5 degree lookdown = 52 - 87 km
17 –27 deg
This plot also ignores earth curvature effects
11-56
Design of UAV Systems
Sensorsc 2002 LM Corporation
• 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
Positive ID considerations
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)
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Design of UAV Systems
Sensorsc 2002 LM Corporation
• 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• Volume = 4.15 cuft• Power req’d = 1160 W
• We solve the problem by using parametric data to resize the SAR • Power req’d = 3000 W• Weight = 350 lbm• Volume = 8 cuft
• The under weather, target identification requirement is satisfied by EO/IR turret type 2 • GRD = 0.3 @ 8 km • Diameter = 15 in• Weight = 100 lbm• Volume = 1 cuft
• Resolution = 10m• Range = 50km• Field of regard = 45
•Power req’d = 700 W
Sensor payloads
95km req’d
We assume resolution and field of regard are unchanged
Or = 0.5m at 13.3 km (from basic optics)
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Design of UAV Systems
Sensorsc 2002 LM Corporation
• 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:• EO/IR = 130 lbm @ 1.95 cuft• SAR = 455 lbm @ 15.6 cuft• Communications (each) = 67.5 lbm @ 4.5 cuft
Installation considerations
Total = 720 lbm @ 26.55 cuft
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Design of UAV Systems
Sensorsc 2002 LM Corporation
• 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 image of spot targets
(goal = 100%, threshold = 80%) in 15 min.• 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)
Requirement summary
1 ID PER HR
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Design of UAV Systems
Sensorsc 2002 LM Corporation
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
Derived requirements
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Design of UAV Systems
Sensorsc 2002 LM Corporation
• 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
Derived requirements
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Design of UAV Systems
Sensorsc 2002 LM Corporation
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.
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Design of UAV Systems
Sensorsc 2002 LM Corporation
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
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Design of UAV Systems
Sensorsc 2002 LM Corporation
Intermission