Extremely Maneuverable UCAV

Team Zebra

Andrew Fischer, Team Leader

Matthew Everingham, Structures and Costing

Connor McCarthy, Aerodynamics and Propulsion

Jim Lang, Project Advisor

Blaine Rawdon, Boeing Company Sponsor

Outline of Presentation• UAV Opportunities• Project Requirements• Mission Profiles• Configuration• Performance• Aerodynamics• Propulsions• Stability and Control• Low Observables• Structure• Future Work• Schedule and Timeline• Conclusions• Special Thanks

UAV Opportunities

Project Requirements

• Create design concept for an extremely maneuverable UCAV that can perform two distinct missions

• Performance up to 9g’s comparable to F-16 & F-15 aircraft for subsonic to transonic flight

• Extended maneuvering capabilities up 20g’s due to increased structural limits and the use of dynamic lift

• Estimate “Value of Maneuverability”

Mission Profiles

•Missions comparable to F-16 and JSF missions

Defensive Counter Air Mission

• Phase 1 – Take off and acceleration allowance• Phase 2 – Climb from sea level to optimum cruise altitude• Phase 3 – Cruise out at optimum speed and altitude for 700 nm• Phase 4 – Combat allowance

• Fuel to perform at 25,000 ft with maximum thrust and fuel flow• One sustained 360º (PS) at M=0.8• Four maneuver-point (instantaneous) 90º turns, recovering to M=0.8 and

25,000 ft altitude after each

• Phase 5 – Climb from 25,000 ft to optimum altitude• Phase 6 – Cruise back at optimum speed and altitude• Phase 7 – Descend to sea level• Phase 8 – Reserves: fuel for 30 minutes at sea level at speed for

maximum endurance

Hi-Lo-Lo-Hi Interdiction Mission

• Phase 1 – Take off and acceleration allowance• Phase 2 – Climb from sea level to optimum cruise altitude• Phase 3 – Cruise out at 500 nm at optimum speed and altitude• Phase 4 – Descend to 200 ft• Phase 5 – Dash out 100 nm at M=0.8 at 200 ft• Phase 6 – Weapons Delivery:

• Small Diameter Bombs are delivered in aggressive turning maneuvers. Retain air-to-air missiles throughout the mission

• Phase 7 – Dash back 100 nm at M=0.8 at 200 ft• Phase 8 – Cruise back 500 nm at optimum speed and altitude• Phase 9 – Descend to sea level• Phase 10 – Reserves: fuel for 30 minutes at sea level at speed for

maximum endurance

Target Laydown

Maneuverability and Speed Issues

• Higher speed requires greater load factor capabilities

• Symmetrical design allows pitching oriented maneuver to replace roll maneuver

• Negative Ps during high g turns complicates the maneuvering

Target Attack Speed versus Load Factor Requirement

0

100

200

300

400

500

600

700

0 5 10 15 20 25

Load Factor

Ve

loc

ity

(k

no

ts)

Sample Tgt Laydown

Targets Attacked per Minute vs Load Factor Capability

0

1

2

3

4

5

6

7

0 5 10 15 20 25

Load Factor

Ta

rge

ts A

tta

ck

ed

/ M

inu

te

Sample Tgt Laydown

Roll Angle vs Load Factor for a Sustained Turn

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25

Load Factor

Ro

ll A

ng

le (

de

gre

es

)

Sustained Turn

Performance: PS

Performance: PS

Performance: Turn Rate vs. Mach

ExMan Exclusive: Dynamic Lift

Take-off and Landing Parameters

• Take-off distance = 1230 ft

• Landing distance = 3678 ft

• Vstall,TO = 155 ft/s

3-View of Planform

Internal Components

Aerodynamic Characteristics

• Leading edge wing sweep - 50°• Aspect Ratio – 4• Taper Ratio, λ - 0.25• Root Chord – 20 ft• MAC – 14 ft• t/c - .09• NACA 0009 Airfoil

• Uncambered• Clmax – 1.32

Drag due to Lift Factor, KMach # vs. K

0

0.05

0.1

0.15

0.2

0.25

0.3

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Mach #

K

Combat Region

MCR

Zero Lift Drag Coefficient, CD0

CD0 vs Mach #

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Mach #

CD

0

Combat Region

MCR

• Drag Polar – CD=.007+.1CL2

(L/D)max

(L/D)max vs. Mach #

0

2

4

6

8

10

12

14

16

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Mach #

(L/D

) max

Combat Region

Stability and Control

• Aerodynamic Center – .25 of MAC• Static Margin - .0285• Longitudinal, lateral and directional neutral stability• Large control surfaces for high pitch acceleration (°/s2)• Leading edge controls for high lift

• Chord length – 3 ft• Acting over >90 % of wing area

• Trailing edge controls for maneuvering• Chord length – 3.8 ft• Acting over 80% of wing area• Plain flaps

High Lift DevicesCL Versus Angle of Attack at M=0.6

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

-20 -10 0 10 20 30 40 50

Alpha, degrees

CL

0 degree T.E. f laps

10 degree T.E. f laps

20 degree T.E. f laps

30 degree T.E. f laps

L.E. f lapsCLbuffet

CLmax

High Lift Devices, cont.CL vs. Angle of Attack at M=0.8

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

-20 -10 0 10 20 30 40 50

Alpha, degrees

CL

0 degrees T.E. f laps

10 degrees T.E. f laps

20 degrees T.E. f laps

30 degrees T.E. f laps

L.E. f laps

ΔCLmax,high lift

Dynamic LiftCL,Dynamic vs. Angle of Attack at M=0.8

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 5 10 15 20 25 30

Alpha, degrees

Cl

0 deg/sec

30 deg/sec

60 deg/sec

90 deg/sec

ΔCLmax,dynamic

ΔCLmax,dynamic is proportional to ά/V

Longitudinal StabilityCM vs. Angle of Attack

-0.05

-0.04

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0.05

-30 -20 -10 0 10 20 30

Alpha, de gre e s

CM

Cm vs. AoA

Trim Point

Propulsion System• Two Pratt & Whitney F-100-PW-100 engines scaled

down a factor of .652 - 1784 lbs each• Combined SLS thrust of 46000 lbs• Dimensioning:

• Engine length – 153.4 in• Compressor face diam.– 32.29 in• Max diam. – 35.5 in• Airflow to each engine – 141.4 lbm/sec• Bleed airflow for each engine – 0.4 lb/sec

• Possible options for operating over 9g’s• Dual-cycle engine (turbofan and ramjet)• Build a 20g engine

Maximum ThrustMaximum Thrust Versus Mach # with Varied Altitude in 1000ft

0

5

10

15

20

25

30

35

40

45

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Mach #

Th

rust,

1000 lb

s

0 ft

5 ft

10 ft

15 ft

20 ft

25 ft

30 ft

0

5

10

15

20

25

30

Military Thrust

Military Thrust Versus Mach # with Varied Altitude in 1000ft

0

5

10

15

20

25

30

35

40

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Mach #

Th

rust,

1000 lb

s

0 ft

5 ft

10 ft

15 ft

20 ft

25 ft

30 ft

0

5

10

15

20

25

30

TSFCTSFC (Max T.) vs. Mach # with Varied Altitude in 1000ft

1.8

1.9

2

2.1

2.2

2.3

2.4

2.5

2.6

2.7

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Mach #

TS

FC

, lb

/lb

-hr

0 ft

5 ft

10 ft

15 ft

20 ft

25 ft

30 ft

0

510

15

20

25

30

Inlet and Nozzle Details

• Axisymmetric pitot inlet – subsonic consideration• Dimensioning:

• Inlet diameter – 24.96 in• Diffuser length – 129.12 in

• S-shape diffuser to reduce radar detection• Pressure recovery in diffuser – 97.14 %• Short convergent nozzle

• Good overall• Potential for thrust vectoring• Slight drag penalty

• Long fairing between nozzle exits• Reduce acoustic interference• Slight drag penalty

Low Observables: Options

• 4 spike configuration• Head on into radar w/ minimal detection

• S-inlet duct w/ radar absorbing material• Increase in LO• decrease in thrust

• Edge Treatments• Increase in LO

• Wempty increase

Center of GravityComponent and Aircraft Center of Gravity

-35

-30

-25

-20

-15

-10

-5

0

-30 -20 -10 0 10 20 30

Y distance (ft)

X d

ista

nce

(ft

)

CG of Aircraft

Engine 1(Left)

Engine 2(Right)

ICNIA

Data bus

INEWS

ALE-50

Vehiclemanagement systemIRSTS

Active Array Radar

LANTIRN NavigationsystemLANTIRN TargetingsystemHARMTargetingsystemElectrical System

APU

OBIGGS

16 250 lb Bombs

Missile Bay 1 (Left)

Missile Bay 2 (Right)

Fuel Tank 1

Fuel Tank 2

Fuel Tank 3

Fuel Tank 4

Front Landing Gear

Rear Landing Gear(Left)Rear Landing Gear(Right)

Travel of Center of Gravity

CG Travel

0

10

20

30

40

50

60

70

80

90

100

89 90 91 92 93 94 95 96 97 98

CG % MAC

Fu

el W

eig

ht

(%)

Structure• 20g structure

• maneuverability outside of human limits• higher lethality

• higher survivability

• Lower factor of safety• Lowered from 1.5 to 1.25

• exploitation of opportunities exclusive to UAVs

• Span Loading• decrease in bending moments on main wing structure

• reduces dependence of structure weight on load factor

Structure Empty Weight Dependence on Load Factor

• The reduction of load factor dependence between span loading and non-span loading was determined using MATLAB model of a basic wing box.• The exponent of load factor was found to be reduced by 0.2, from 0.59.

• Normally, a refined empty weight estimate made based on historical data for A/C components.• In this case, the load factor dependence determined from the MATLAB

program was used with the historical data to produce an empty weight estimate of ExMan.

• An empty weight estimate of the F-16 configuration was also created, using the same historical relations, but with the body-wing dependence on load factor.

Structure Empty Weight Dependence on Load Factor(continued)

• The relation of empty weight to load factor based on the actual empty weight of the F-16 was created to determine the empty weight of an F-16 which has been scaled up to handle up to 20gs.

• A similar relation for the empty weight of ExMan was determined assuming the same quantity of non-load factor dependent weight.

• Targets hit per minute was related to empty weight for each aircraft through the design load factor and minimum required turn radius for sample target laydown.• The relation shows that the ExMan UCAV will weigh less than the F-16

for any given load factor.• The ExMan UCAV at a design load factor of 20 is lighter than the F-16 at

a design load factor of 9.

Empty Weight vs Load Factor Capability

0

5000

10000

15000

20000

25000

0 5 10 15 20 25

Load Factor

Em

pty

We

igh

t

Conventional Body-Wing

Span-Loader Config

Possible Trade Studies

• PW-F-100 vs. GE-404 engine

• Double vs. single engine design

• Leading edge inlets vs. top-bottom bifurcated inlets

• Inlet flaps for flow straightening

• Control effectors (ie. Thrust vectoring)

• Mission Radius

• Fuel layouts

Targets Attacked per Minute vs Empty Weight

0

1

2

3

4

5

6

7

0 5000 10000 15000 20000 25000

Empty Weight

Ta

rge

ts A

tta

ck

ed

/ M

inu

te

Conventional Body-Wing

Span-Loader Config

F-16

Ex Man UCAV

Conclusions•Performance up to 9g’s comparable to F-16 & F-15 aircraft for subsonic to transonic flight•Extended maneuvering capabilities up to 20g’s due to increased structural limits and the use of dynamic lift•Symmetric design able to perform positive and negative maneuvers with equal performance•Span loading concept results in a lightweight aircraft

Schedule and Timeline

Targets Attacked per Minute vs Empty Weight

0

1

2

3

4

5

6

7

0 5000 10000 15000 20000 25000 30000

Empty Weight

Ta

rge

ts A

tta

ck

ed

/ M

inu

te

Conventional Body-Wing

Span-Loader Config

F-16 type based onhistorical data

Ex Man UCAV