conceptual design of an unmanned combat aerial vehicle...
TRANSCRIPT
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Conceptual Design of an Unmanned
Combat Aerial Vehicle (UCAV) by Ray Whitford
Department of Aerospace, Power & Sensors
Royal Military College of Science,
Defence Academy of the UK
with PW-125 Case study by Zdobyslaw Goraj
Warsaw University of Technology
Lecture 15, Warsaw, 17.06.2020
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Topics
• Manned versus unmanned vehicles
• Requirements
• Competition
• Stealth
• Structures
• Powerplant (Engine, Inlet, Nozzle)
• Mass Breakdown
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Man v Machine (1/2) The pilot against the unmanned vehicle
Pilot Advantages Pilot Disadvantages
Adaptability and flexibility (elastyczność)
Mental processing from wider
variables (Wyższość umysłu nad sztucz.Inteligencją)
Moral and political control (motywacja)
Unpredictable behaviour against the
enemy (Pozytywne reakcje w sytuacjach
nieprzewidywalnych)
Physical shape and frailty (słabości)
Need for rest and sleep (zmęczenie)
Inability to self repair during mission (niemożność samonaprawy)
Fear (strach)
Cost of Training and Currency (koszt
szkolenia, nie domaga się podwyżki!)
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UCAV
Advantages
UCAV
Disadvantages
Durability (długotrwałość misji)
Lack of a vulnerable human (człowiek
jest „urazowy”)
Lower operating cost (niższy koszt
operacyjny)
Expendability (łatwiej uzupełniać braki)
Greater stealth (łatwiej o niskie RCS)
Decision making entity -
undeveloped AI technology (wciąż niedorozwój Artificial Intelligence )
Bandwidth requirements (częstotliwości)
Programmed, lack of flexibility (brak
elastyczności w działaniu)
Smaller warload (słabsze możliwości bojowe)
Limited sensors (niedorozwój czujników)
Man v Machine (2/2)
The pilot against the unmanned vehicle
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Minimum Design Life
Typical system
Current Fighter
design life
UCAV life
Airframe
8,000 hr
300-500 hr
Landing gear
7,500 cycles
300-500 cycles
Radar
10,000 hr
300-500 hr
Environment cont
system
8,000 hr
300-500 hr
Engine hot section
4,000 cycles
300-500 hr
Engine cold section
8,000 cycles
300-500 hr
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Requirements
• Fully autonomous flight
• In-flight Refuellable
• Combat radius of 1200 nm
• Assorted ordnance up to 2000 lb
• Max speed M=0.9
• Able to operate from 2000m runways
Wyselekcjonowane uzbrojenie
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Possible Roles
• SEAD and DEAD
• Attack from low- medium- & high-altitudes
• Specialist Reconnaissance
• Naval Strike/Reconnaissance
• Electronic Warfare
Suppression of Enemy Air Defence and Destruction of Enemy Air Defence
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Ordnance
• Laser Guided Bombs: Paveway 1000lb
• Anti-Radiation Missiles: ALARM
• Multiple Small Diameter Bombs (SDB)
• Multiple Munitions Dispensers
2000lb JDAM
Paveway
SDB
Joint Direct Attack Munition (JDAM) is a guidance kit
that converts unguided bombs, or "dumb bombs",
into all-weather "smart" munitions
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Threats
AWACS & Fighters High Altitude SAMS
Low & Medium Level SAMS MANPADS
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The Competition
Predator X-45A
X-47 X-46
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Stealth
• Radar
• Infrared / Thermal Imaging
• Aural
• Visual
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Increased Survivability
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Stealth Design • Straight Parallel Edges
• Continuous Curvature
• Clean Underside (internal weapons)
• Intake & Exhaust Hidden
• Sawtooth Edges on Doors
• Vectored Thrust Trim for Yaw and Pitch
• Cold Air Bypass
• Low Electronic Emissions
• Radar Absorbent Material
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Possible Planforms
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Planforms
• Wing Area: 75 m2
• Span: 21.13 m
• Sweep Angle: 40o
• Fuselage Length: 9 m
• Aspect Ratio: 5.95
• Taper Ratio: 0.29
Early low
aspect ratio design
Early VERY low
aspect ratio concept
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Size Comparison
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Internal Layout This highlights a major problem:
Cutting big holes in the bottom of the
vehicle
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Internal Layout
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Structural Layout
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Structural Layout
FWD
Weapons
Bays
& Engine
Empty space:
Structurally
unsound:
A major problem
Box
Frames
To
withstand
Torsion
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Fuel Tanks
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Internal Layout
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Engine
• Eurojet EJ 200 Selected
• War Mode Produces 65kN (SL ISA)
• T/W : 0.45
• 7% installation Loss
• SFC (M=0.8, 11km) = 28 mg/Ns
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Air Inlet • Mask the Compressor Face
• Low Profile Capture Face
• Use of Blockers and RAM
• Exterior Shaping
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Inlet Treatment
Blocker
Engine
Face
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Versatile Affordable Advanced
Turbine Engine (VAATE)
Versatile Affordable Advanced Turbine Engine
(VAATE)
Stealthy but very poor aerodynamics
due to adverse pressure gradients
Stealthy but poor aerodynamics (so thrust LOSS)
AND exhaust duct wants to circularise
Line-of-sight
blockage
Distortion-tolerant fan
Vectoring
nozzle
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Air Inlet
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Propelling Nozzle
• High On-Design Thrust
• Low IR Signature
• Low Radar Cross Section
• Thrust Vectoring
• High Aspect Ratio
• Mixer Nozzle
• Upper Surface Location
• Use of Ceramics
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Propelling Nozzle
• Provide For Trimming Of Aircraft
• 3-D Vectoring • Vertical – Fluidic
• Horizontal – Mechanical
FWD
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• Mainly responsible for trim
• Additional pitch or yaw control
• Combination of vanes for directional control and fluidic thrust vectoring allows 3-D vectoring
• Not immediately dependent on engine throttle response, thus relatively fast-acting
Propelling Nozzle
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Mass Breakdown
Fuel
32%
Structure
16%Landing
Gear
4%
Powerplant
11%
Systems and
Equipment
16%
RAM
15%
Payload
6%
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Use of Radar Absorbing Material
RAM Weight: 2300kg
15% MTOW
25% Empty Wt
Polychloroprene + carbonyl iron ferrite
(10% by weight)
Used in parasitic form (not as structure)
for external skin and lining for air inlet
To defeat 3cm (10GHz) radar
requires 7.5mm thick RAM
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Range - Hi Hi Profile
1300 nm
2600 nm
Take-off Landing
45000 ft, M0.82 51000 ft, M0.82
Weapons release
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Range - Hi Lo Hi Profile
630 nm
1460 nm
45000 ft, M0.82 50000 ft, M0.82
Take-off Landing
5000 ft
250 ft, M0.9
200 nm 630 nm
Weapons
release
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UAV flight safety events (based on 120,000 flt hrs of IAI UAVs)
Propulsion
24%
Misc
7%
Flight control
28%
Power
system
8%
Comms
11%
Human error
22%
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PW-124
a high maneuverability, case study UCAV project
anticipated as a future
ground attack aircraft
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Fundamental assumptions 1/3
Main goal: to design, build and prepare
the flight tests of a small, highly manoeuvrable
unmanned aerial vehicle of the reduced radar,
infrared and acoustic signature
First priority: high manoeuvrability Potential future application: ground attack mission
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Fundamental assumptions 2/3
Competitors? Rather niche !
PW-124
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Fundamental assumptions 3/3
Competitors? Rather niche !
•Role of the specialized so-called „ground attack aircraft” is widely
accepted and beyond any discussion. Examples: A10, Su25
•UAVa being now in service or UCAVs in design progress are
multi-mission, so they are not specialized in ground attack.
•Survivability strongly depends on manoeuvrability. Well known
UCAVs as not highly manoeuvrable, can not be very efficient
in ground attack mission. Manned aircraft can be never highly
manoeuvrable ( human g limit!)
•Conclusion: there is a luck of any UCAV specialized for ground attach mission!
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Design assumptions 1/6
•High manoeuvrability (load factor of order 15)
at a relatively small thrust surplus
•Low cost due to small weight and small
dimensions ($1mln is anticipated)
•Cheap turbojet engine (Microturbo TRI 60-5;
SLS 440 kG Thrust)
•Highly sophisticated carbon fibre structure,
light and of high strength
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Design assumptions 2/6
•Compact configuration based on cranked
delta wing, endowed with fixed slots, tab-flaps
and elevons / rudderons, easy to control about
three axes
•Payload compartment of required volume
(width, heigth & length) has to be placed
(hidden) in the central part of the body (CG
position insensitive to the weight change after
the payload is released)
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Design assumptions 3/6
•Reduced RCS is much less weighted now than
manoeuvrability - it will be developed in the
future but under the condition if it does not
change the aerodynamic characteristics
essentially for the worse
•Radius of mission equal to 200 km
•Time of pure combat is limited to 5 min
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Design assumptions 4/6
•Low sensitivity to gust will be achieved due
to relatively low lift-curve slope of order 2.2
per radian and a moderate wing loading of
order 60 kg/m2
•Curved air inlet designed to reduce the RCS
of the engine compressor face
•Essential Ph.D. students participation
in the design effort
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Design assumptions 5/6 Typical UCAV missions
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Design assumptions 5/6 PW-124 - a typical mission
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External layout 1/3
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External layout 2/3
•blended wing body configuration
•Wing control surfaces provide
longitudinal balance
•high wing dihedral (+20; -31)
provide directional stability
•retractable landing gear
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External layout 3/3 Longitudinal control surfaces
Lateral control surfaces Bottom inlet for air & hot gas mixer
Bottom inlet for air
& hot gas mixer
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Configuration of main systems
engine Fuel tanks
battery
Electronic equipment
parachute
EO system
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Main body structure
Payload compartment
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Power unit
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Selected parameters 1/2
Wing span 4,5 m
Wing area 11,8 m2
Body length 5 m
Height (in flight) 0,9 m
Height (on runway) 0,9 m
Aspect ratio 1,76
Payload volume (length x width x height) 2 m x 0,6 m x 0,5 m
Empty weight 300 kg
Payload 200 kg
Fuel weight 400 kg
Nominal take-off weight 800 kg
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Selected parameters 2/2
Maximum take-off weight 900 kg
Maximum manoeuvring weight 650 kg
Take-off thrust 4,4 kN
Take-off wing loading 78 kg/m2
Manoeuvring wing loading 56,5 kg/m2
Manoeuvring thrust loading 148 kg/kN
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Aerodynamic analysis
6200 panels, 28 patches
Body centre airfoil
(with modified both LE
and TE)
NACA
0012-64
Body – outer wing
junction airfoil (in the
plane parallel to the
vertical plane of
aircraft symmetry)
NACA 651-
412
Outer wing airfoil (in
the plane parallel to the
vertical plane of
aircraft symmetry)
NACA 651-
412
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Asymmetric flow
Cp at =3,38o, =0o,
F=0o, E,l=+10o, E,r=-10o
Cp at at =3,38o, =10o
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Lift and pitching moment
CL( )
-0,8
-0,4
0
0,4
0,8
1,2
-10 0 10 20
CLCL_d 0
CL_d 10
CL_d -10
CMY( )
-0,08
-0,04
0
0,04
0,08
-10 0 10 20
CMYCMY_d 0
CMY_d 10
CMY_d -10
Lift coefficient versus angle of attack
for clean configuration (d=0),
flap-tabs deflected down (d=10) and
flap-tabs deflected up (d=-10); Ma=0.5,
Re=28x106
Pitching moment coefficient computed
about a quarter point of MAC versus
angle of attack for clean configu-
ration (d=0), flap-tabs deflected down
(d=10) and flap-tabs deflected up
(d=-10); Ma=0.5, Re=28 mln
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Flight envelope
0 50 100 150 200
-10
-5
0
5
10
15
n
PW-124
V [m/s]
w=15
w=7,5
w=-7,5
w=-15
Cz m
ax
A D
G F
E
Vs1=28
Vs1'=39
VA=107 VD=211
VC=136
VG=124
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Performance
0 200 400 600
Flight speed [km/h]
0
2
4
6
8
10
Fli
gh
t A
ltit
ud
e [
km
]
0 50 100 150
Max rate of climb [m/s], Max climb angle [deg], time to climb [min]
time to climb
Vmax
Vmin
flight speed of max. rate of climb
flight speed of max. climbe angle
rate of climb
climb angle
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Range and endurance PW-124 - Endurance and Range (H=1.5km, W=900kg, WFUEL=350kg)
100 200 300 400 500 600
TAS [km/h]
0
1
2
3
Endurance [h]
0
200
400
600
800
Range [km]
Endurance
Range
60
Sensitivity to gust
tVm
CSq
g
L
eW
W
1
L
gC
V
WWSVWm
2
21
0 0.2 0.4 0.6 0.8 1
time [s]0
0.2
0.4
0.6
0.8
1
vert
ical
dim
en
sio
nle
ss d
isp
lacem
en
t
du
e t
o g
ust
(W/W
gu
st)
small lift-curve slope Cl= 2.2
high lift-curve slope Cl= 4.6
Aircraft of lower aspect ratio
is less sensitive to gust than that
of higher aspect ratio
Aircraft of lower wing loading
(high S/m) is more sensitive to gust
than that of higher wing loading
61
RCS has to be minimized
Predicted signature of a generic aircraft
Edges, panels etc. have to be grouped on
a minimum number of alignments. Then the strongest
edge reflections will be seen only at four relatively
narrow azimuth zones
Up to azimuth 30 the box type air
intakes totally dominate the signature
RCS dominated by wing edges
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Stealth Design • Straight Parallel Edges (partly)
• Continuous Curvature
• Clean Underside (internal weapons)
• Intake & Exhaust Hidden (partly)
• Sawtooth Edges on Doors (easy to be done)
• Vectored Thrust Trim for Yaw and Pitch (no)
• Cold Air Bypass (partly)
• Low Electronic Emissions (no)
• Radar Absorbent Material (no)
63
Wing design
Double-circuit torsion box,
made of epoxy-carbon composite
takes the torsion loading
Upper and lower skins are made of
sandwich with a filler made
of polyurethane foam
Spar flanges are made of carbon roving
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Configuration (1/8)
Payload containers opened in flight –
both covers are deflected down
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Configuration (2/8)
Internal payload containers are opened,
all undercarriage legs deflected down.
Double covers of each undercarriage
containers are well visible
66
Configuration (3/8) A bottom-side view:
Internal payload containers are closed,
all undercarriage legs deflected down.
Double covers of each undercarriage containers
are well visible. Aircraft is ready to land.
67
Configuration (4/8)
Internal payload containers
are closed, all undercarriage legs
deflected down. Double covers of
each undercarriage containers
are well visible. Aircraft is ready to
land
68
Configuration (5/8)
Elevons deflected asymmetrically
(left elevon deflected down, right deflected up)
Flap-tabs (at the trailing edge of the
blended-wing body) deflected up
(it is typical in horizontal flight for
equilibrium of pitching moments).
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Configuration (6/8)
Horizontal flight – clean configuration
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Configuration (7/8)
Clean configuration from a top-front-side view.
Flight spoilers deflected
71
Configuration (8/8)
Clean configuration from a top-back-side view.
Flight spoilers deflected.
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Conclusion (from London conference)
•For successful design project 3 elements are needed:
•bright idea in a proper time
•experienced, well motivated team
•money for research and design activity
•Requirements for PW-124: high manoeuvrability,
low sensitivity to gust, low cost
•Independently on the external support this project
will be continued, because it contain a number
of fascinating subtasks to be solved.
•If the project is successful an interest of governmental
agencies is expected. We are looking for any kind of
cooperation for future business!