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 c 2003 LM Corporation Requirements analysis 8-1
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 c 2003 LM Corporation Requirements analysis 8-2
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 c 2003 LM Corporation Requirements analysis 8-3
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 c 2003 LM Corporation Requirements analysis 8-4
Worldwide airport data Design of UAV Systems Worldwide airport data Data Source - (Total = 45,024) What runway length do you design for? c 2003 LM Corporation Requirements analysis 8-5
What type runway do you design for? Design of UAV Systems Typical unpaved field http://www.eden.com/~tomzap/b_apt.html What type runway do you design for? c 2003 LM Corporation Requirements analysis 8-6
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 c 2003 LM Corporation Requirements analysis 8-7
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 www.odci/cia/publications/factbook/indexfld.hmtl 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 c 2003 LM Corporation Requirements analysis 8-8
Design of UAV Systems Airport data Airports - China Airports - ROK 10 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 c 2003 LM Corporation Requirements analysis 8-9
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 c 2003 LM Corporation Requirements analysis 8-10
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 - 3000 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 c 2003 LM Corporation Requirements analysis 8-11
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 c 2003 LM Corporation Requirements analysis 8-12
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 c 2003 LM Corporation Requirements analysis 8-13
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 c 2003 LM Corporation Requirements analysis 8-14
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 c 2003 LM Corporation Requirements analysis 8-15
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 c 2003 LM Corporation Requirements analysis 8-16
Design of UAV Systems Aircraft Carriers CVN-68 Nimitz-class 1092 ft (333 m) 252 ft (77 m) Crew 5680 http://www.fas.org/man/dod-101/sys/ship/cvn-68.htm 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 c 2003 LM Corporation Requirements analysis 8-17
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) http://www.fas.org/man/dod-101/sys/ship/cvn-68.htm 844 ft (253 m) c 2003 LM Corporation Requirements analysis 8-18
Design of UAV Systems Typical assault ship http://sun00781.dn.net/man/dod-101/sys/ship/LHD12.JPG Decks are crowded and space is limited c 2003 LM Corporation Requirements analysis 8-19
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 www.wa3key.com/growler.html Regulus - 1950s Pioneer - 1990s http://www.fas.org/irp/program/collect/pioneer.htm c 2003 LM Corporation Requirements analysis 8-20
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 http://www.fas.org/irp/program/collect/pioneer.htm http://www.fas.org/irp/program/sources.htm http://www.lmaeronautics.com/image_gallery/index.html c 2003 LM Corporation Requirements analysis 8-21
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 www.wa3key.com/growler.html http://www.fas.org/man/dod-101/sys/smart/bgm-109.htm c 2003 LM Corporation Requirements analysis 8-22
Operating UAVs from subs has been demonstrated Design of UAV Systems UAV operations http://www.fas.org/irp/agency/daro/uav96/page32.html Operating UAVs from subs has been demonstrated Launching UAVs from subs is being studied - Size and weight penalties are significant http://www.lmaeronautics.com/image_gallery/index.html c 2003 LM Corporation Requirements analysis 8-23
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 c 2003 LM Corporation Requirements analysis 8-24
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 http://www.dfrc.nasa.gov/gallery/photo/index.html c 2003 LM Corporation Requirements analysis 8-25
Design of UAV Systems More reasonable sizes Orbital Sciences Pegasus http://www.spectrumwd.com/c130/dc130p1.htm Ryan AQM-34N Span: 32 ft. Weight: 3,830 lbs. Length: 30 ft. Speed: 420 mph Height: 6.75 ft. Range: > 2000 NM http://209.207.236.112/irp/program/collect/aqm-34n.htm Orbital Sciences Pegasus Span: 22 ft. Diameter: 4.2 ft. Length: 55 ft. Weight: 51 Klb c 2003 LM Corporation Requirements analysis 8-26
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 c 2003 LM Corporation Requirements analysis 8-27
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 2003 LM Corporation Requirements analysis 8-28
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 c 2003 LM Corporation Requirements analysis 8-29
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 c 2003 LM Corporation Requirements analysis 8-30
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 - 200 nm @ 225 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 c 2003 LM Corporation Requirements analysis 8-31
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 12500-13500 nm range permits self deployment anywhere in the world without aerial refueling c 2003 LM Corporation Requirements analysis 8-32
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) ≈ 0.87sqrt [2H(ft)] LOS @ 10Kft = 123 nm LOS @ 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 c 2003 LM Corporation Requirements analysis 8-33
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 c 2003 LM Corporation Requirements analysis 8-34
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 c 2003 LM Corporation Requirements analysis 8-35
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 c 2003 LM Corporation Requirements analysis 8-36
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 c 2003 LM Corporation Requirements analysis 8-37
Geographic area coverage? Design of UAV Systems Geographic area coverage? 600 nm 1200 nm c 2003 LM Corporation Requirements analysis 8-38
- 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 2003 LM Corporation Requirements analysis 8-39
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. c 2003 LM Corporation Requirements analysis 8-40
Design of UAV Systems Example Unfortunately fallingrain.com no longer maintains this site This is the output from WAPF at http://www2.fallingrain.com.air/ 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 c 2003 LM Corporation Requirements analysis 8-41
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 1052.00 zgkl 1104.00 zuck 1130.00 zppp 1142.00 zuuu 1243.00 zgnn 1281.00 zghk 1302.00 zwww 1931.00 zwtn 2315.00 zwsh 2463.00 c 2003 LM Corporation Requirements analysis 8-42
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? c 2003 LM Corporation Requirements analysis 8-43
Does this help you answer? Design of UAV Systems Does this help you answer? c 2003 LM Corporation Requirements analysis 8-44
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 - http://cessna.com/aircraft/ c 2003 LM Corporation Requirements analysis 8-45
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 2003 LM Corporation Requirements analysis 8-46
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 2003 LM Corporation Requirements analysis 8-47
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 1052.00 zgkl 1104.00 zuck 1130.00 zppp 1142.00 zuuu 1243.00 zgnn 1281.00 zghk 1302.00 zwww 1931.00 zwtn 2315.00 zwsh 2463.00 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 c 2003 LM Corporation Requirements analysis 8-48
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)? c 2003 LM Corporation Requirements analysis 8-49
Lowest cost to meet requirements Design of UAV Systems Cost effectiveness Relative income = 12hrsBlock time Relative cost (assumption) - 60 kt UAV = 1.00 - 120 kt UAV = 2.00 - 240 kt UAV = 4.00 - 480 kt UAV = 8.00 - 960 kt UAV = 16.00 Best option = 240 kts Lowest cost to meet requirements c 2003 LM Corporation Requirements analysis 8-50
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. c 2003 LM Corporation Requirements analysis 8-51
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 c 2003 LM Corporation Requirements analysis 8-52
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 2003 LM Corporation Requirements analysis 8-53
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 c 2003 LM Corporation Requirements analysis 8-54
Review cont’d Design of UAV Systems 200 nm Surveillance area Loiter location(s)? 100 nm Surveillance area c 2003 LM Corporation Requirements analysis 8-55
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”? c 2003 LM Corporation Requirements analysis 8-56
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%” c 2003 LM Corporation Requirements analysis 8-57
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” c 2003 LM Corporation Requirements analysis 8-58
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 c 2003 LM Corporation Requirements analysis 8-59
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 2003 LM Corporation Requirements analysis 8-60
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 2003 LM Corporation Requirements analysis 8-61
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 2003 LM Corporation Requirements analysis 8-62
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 2003 LM Corporation Requirements analysis 8-63
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 2003 LM Corporation Requirements analysis 8-64
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 =141 nm @ 282 kts @10 Kft Payload weight and volume = TBD Payload power required = TBD c 2003 LM Corporation Requirements analysis 8-65
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 2003 LM Corporation Requirements analysis 8-66
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 2003 LM Corporation Requirements analysis 8-66a
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 Email to Egbert by COB next Thursday c 2003 LM Corporation Requirements analysis 8-67
Intermission Design of UAV Systems c 2003 LM Corporation Requirements analysis 8-68