8-1 design of uav systems requirements analysisc 2003 lm corporation lesson objective - to discuss...

8-1

Design of UAV Systems

Requirements analysisc 2003 LM Corporation

Lesson objective - to discuss

Requirements analysis

including …• Basing• Operational radius• Operational endurance• Maximum range• Speed• Turn around time

plus …• Example problem

8-2



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

Definition

8-3



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

8-4



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

Land Based Operations

8-5



Worldwide airport data

Airports - Worldwide

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> 10Kft > 8Kft > 5Kft > 3Kft Total

Runway Length

Nu

mb

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(%)

Unpaved

Paved

http://www.odci.gov/cia/publications/factbook/indexfld.htmlData Source -

(Total = 45,024)

What runway length do you design for?

8-6



Typical unpaved field

http://www.eden.com/~tomzap/b_apt.html

What type runway do you design for?

8-7



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

8-8



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

8-9



Airport data

Airports - China

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Runway Length (Kft)

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%)

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Airports - ROK

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Runway Length (Kft)N

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UnpavedPaved

http://www.odci.gov/cia/publications/factbook/indexfld.html

8-10



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

8-11



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 5.4Bottom 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

8-12



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

8-13



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

8-14



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

Unprepared fields

8-15



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

8-16



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

8-17



Aircraft Carriers

1092 ft (333 m)

252 ft (77 m)

Crew 5680

http://www.fas.org/man/dod-101/sys/ship/cvn-68.htm

Fixed Wing Aircraft14 F-14 Tomcat 4 EA-6 Prowler36 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

8-18



Assault Ships

Crew 1100 Sailors1900 Marines

Fixed Wing AircraftUp to 20 AV-8B Harriers

HelicoptersUp to 42 CH-46Sea 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-1Wasp-class

252 ft (77 m)

200 ft (61m)

http://www.fas.org/man/dod-101/sys/ship/cvn-68.htm

844 ft (253 m)

8-19



Typical assault ship

http://sun00781.dn.net/man/dod-101/sys/ship/LHD12.JPG

Decks are crowded and space is limited

8-20



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

8-21



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

8-22



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

8-23



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

8-24



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

8-25



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

http://www.dfrc.nasa.gov/gallery/photo/index.html

8-26



More reasonable sizes

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

8-27



Aerial recovery

• AQM-34 reconnaissance drones were recovered in mid air during the Vietnam war

• 65% of the drones were successfully recovered, many using a Mid Air Retrieval System (MARS) equipped helicopter which performed an aerial “snatch”

• Despite past success, aerial recovery is complex and dangerous (for the helicopter)

• I can find no pictures of the recovery system but take my word for it, aerial recovery of UAVs is very difficult

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Next subject(s)

8-29



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

Operational radius and endurance

8-30



RQ-4A question

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

Where did 24 hours and 3000 nm come from?

8-31



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

8-32



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

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%

8-33



Range and endurance impact

Examples

* More about this in lesson 9

8-34



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

Fleet size

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

8-35



Time on station – cont’d

If time on station = 2 hrs, 13 vehicles req’d, one launch every 2 hours

24 hour coverage

24/7 Coverage

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Time on station (hrs)

Size RequiredGlobal Hawk type

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24/7 Air Vehicle Cost@ $2000/lb

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* Air vehicle cost excludes payload (which should be included) - more about this later

8-36



• 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

8-37



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

8-38



600 nm

1200 nm

Geographic area coverage?

8-39



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?

8-40



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.

8-41



Example

• 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

Unfortunately fallin

grain.com

no longer maintains this site

8-42



The data set

ICAO ID Distance(nm)

zsqd 381.00zytl 390.00zsss 411.00zshc 488.00zsnj 499.00zycc 545.00zbtj 567.00zsof 574.00zsfz 700.00zhcc 701.00zhhh 743.00zbyn 762.00zsam 817.00zbhh 841.00zgha 863.00zggg 1052.00zgkl 1104.00zuck 1130.00zppp 1142.00zuuu 1243.00zgnn 1281.00zghk 1302.00zwww 1931.00zwtn 2315.00zwsh 2463.00

8-43



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?

25 Major Airport Coverage - China

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8-44



Does this help you answer?

8-45



Speed

Why is it important?• It has a major impact on the cost and complexity of the air vehicle - Speed costs!

Cessna Aircraft - Cost per pound

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Maximum TAS (kts)

Piston Engine

TurbopropJet

Piston Engine

Data source - http://cessna.com/aircraft/

8-46



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

8-47



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

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)

8-48



Sortie length analysis

ICAO IDDistance(nm)

zsqd 381.00zytl 390.00zsss 411.00zshc 488.00zsnj 499.00zycc 545.00zbtj 567.00zsof 574.00zsfz 700.00zhcc 701.00zhhh 743.00zbyn 762.00zsam 817.00zbhh 841.00zgha 863.00zggg 1052.00zgkl 1104.00zuck 1130.00zppp 1142.00zuuu 1243.00zgnn 1281.00zghk 1302.00zwww 1931.00zwtn 2315.00zwsh 2463.00

Min. coverage

50% coverage

90% coverage

8-49



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)

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)?

China - Speed Sensitivity(40 kt headwind)

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Average Air Speed (kts)

Min. Coverage

90% Coverage

100% Coverage

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Block speed (kts)

8-50




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Relative cost

Min. Coverage90% Coverage100% Coverage

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


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Relative cost

Min. Coverage90% Coverage100% Coverage

8-51



• 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.

China - 2 Hours On The Ground(40 kt headwind)

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China - 2 Hours On The Ground(40 kt headwind)

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Block speed (kts) Block speed (kts)

China - 2 hour turnaround China - 4 hour turnaround

8-52



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

8-53



Next subject




plus …• Example problem

8-54



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 effectsMinimum required trades

- Communication architecture- Sensor(s) required- Control architecture- Operating altitude(s)- Time on station- Loiter pattern and location

8-55



Review cont’d

200 nm

Loiter location(s)?

100

nm

Surveillance area

200

nm

8-56



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”?

8-57



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%”

8-58



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”

8-59



Candidate system solutions

• And high speed required- From 262 kts

• One large UAV with long range WAS sensor- Minimum WAS range required for 80% target area coverage = 101nm (187km); h = 53.7 Kft

• Communications ranges potentially very long- Up to 316 nm (h > 65 Kft)

• Lots of climbs and descents

Note – required distance calculations assume no ID sensor range extension 100 nm

200 nm x 200 nm

Loiter location

141 nm in 30 min. = 282 kts

Target 1 location

316 nm282 nm in 30 min.

= 564 kts

Target 2 location

to 512 kts

- Maximum WAS range = 202 nm (374 km); h > 100 Kft

8-60



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 nmLoiter locations

Target 1 location

141 nm in 30 min. = 282 kts

Target 2 location

8-61



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

27 Kft

27 Kft

10 Kft

8-62



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

8-63



Our starting approach

• But only one UAV responds to target ID requests• No need to switch roles, simplifies ConOps• No need for frequent climbs and descents

• Five medium UAVs, four provide wide area search, a fifth provides positive target identification- WAS range required (95km) not a challenge

• 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

27 Kft

27 Kft

27 Kft

8-64



• 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)

Requirement summary

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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

Derived requirements

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• 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• Uninstalled weight/volume/power = TBD

• Communications • Range/type = 212nm/air vehicle and payload C2I

• Uninstalled weight/volume/power = TBD• Range/type = 158nm/communication relay

• Uninstalled weight/volume/power = TBD• Control Station element

• TBD• Support element and sortie rates

• To be determined

Derived requirements

C2I = Command Control and Intelligence

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MIEOE requirements*

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

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Homework

Do a first-order requirements analysis on your UAV system project and select an initial system concept(1)H(1) How many vehicles are required? Explain why(2)((2) What speeds and altitudes are required?

- Document the calculations that support your conclusions including intermediate steps.

(3)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

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Intermission

8-1 design of uav systems requirements analysisc 2003 lm corporation lesson objective - to discuss...

Documents

requirements analysisit

level uav requirements

uav air vehicle element

automated uav delivery

uav takeoff

design team

traceable set of design

lowest cost