Virginia Tech and Loughborough University present:
Ikelos
2001/2002 Interdisciplinary/International
Aircraft Design Project
Original Specification
Key Requirements:
• Aircraft fits on trailer
• Lightweight and Simple
• STOL or VTOL
• Land in 46m (150ft) over 5m
obstacle
• Cruise > 90 kts
• Range > 150nm
• 1 Seat Aircraft
Initial Design Ideas
Each group produced 3 concepts:
• Counter-rotating Helicopter
• 2 Gyroplanes
• VTOL tilt duct
• Vectored jet
• Pusherprop
Selected VTOL Tilt duct:
• Most adaptable
• Most Original
Initial Concepts
VTOL Tilt
Duct
Pusher Prop
Design Development
Reviewed advantages and disadvantages of:
• STOL
• VTOL
• Vectored Thrust
Modified Design to:
• STOL as standard aircraft
• Vectored thrust option
Revised Specification
• 46m (150ft) ground roll
• Meet SSTOL requirement 150m (500ft) over
15m (50ft) obstacle
• Cruise speed to be competitive with GA aircraft:
110kts – 150kts
• Range - 500nm at cruise speed
• 2 Seat Aircraft
Configuration
Configuration
Fuselage Structure Layout
Wing Structure Layout
Loughborough
University
Wing Detachment
• Trailer criteria of 2.2m max. width
• Front Wing:
•I – section spars overlap in fuselage, bolted
together in hollow box structure
• Rear Wing:
•Connected to top of tail using two “3-way”
brackets
• Vertical Spars:
•Bolted to outer ribs using hollow tube
connections
Materials
• Glass epoxy skin on wings and fuselage
• Skin is honeycomb sandwich
• Kevlar reinforcement on fuselage bottom and
lower wing skins
• Structure framework of carbon fiber with metal
reinforcements in critical areas
• Aluminum firewalls and steel undercarriage
V-n Diagram
V-n diagram
6.0
5.0
4.0
3.0
2.0
n
1.0
0.0
-1.0
-2.0
-3.0
-4.0
-5.0
0
10
20
30
40
50
60
Velocity (m/s)
Clean Cruise Pos
Vc
Neg Gust (50)
Clean Cruise Neg
Vd
Neg Gust (25)
Stall
Full Flaps
Neut Gust
Pos Maneuvering Limit
Gust (50)
Neg Maneuvering Limit
Gust (25)
Manufacturing
• Planes assembled in individual bays
• Composites used where possible
• Internal skeleton
• Assembly team at each bay
• Team unity and pride in work
• Important due to the complexity of
wiring, controls, and electronics
Tornado VLM
• Non-planar vortex lattice method
• Incorporates various wing features
Wing Layout
• Box-wing design
• Front wing twisted
• Unswept inboard TE flap
Lift Characteristics
• Based on forward wing area
• CLMAX = 4.19
• Leading edge devices
• Front wing flapped
• Fowler te flaps, fixed vane
Drag Characteristics
• Induced drag reduction
• CD0 = .045 in cruise
WINGS
35%
INLETS AND
OUTLETS
12%
SIDE PLATES
3%
12%
OTHER
17%
FUSELAGE
24%
UNDERCARRIAGE
5%
DUCTS
VERTICAL
TAIL
4%
Stability and Control
• Static Stability
• Design Criteria: Acceptable static margin in
all configuration, FAR 23 compliance
• Final Configuration balanced (positve Cm0L)
with positive pitch stiffness (negative Cma)
• Lateral-Directional stability satisfied but
nearly neutral to retain maneuverability
• Dynamic Stability
• Design Criteria: MIL-F-8785C
specifications with Level 1 flight qualities
Control Surfaces
• Aircraft equipped with standard elevators,
ailerons, and rudder
Ailerons
Elevators
Rudder
Area (sq m) % Chord Span (m)
0.586
30
0.9
1.496
30
1.9
0.41
24
1.29
Sizing Condition
Comparable Aircraft
Take-off Rotation
Maximum Crosswing Landing
Trim Diagram
0.8
v = 65 m/s
S = 8.65 sq. m
0.6
Xcg = Xcg forward
0.4
CLmax
0.2
Cm
-10 deg
0
0
0.5
1
1.5
2
2.5
3
3.5
0 degrees
-0.2
Xcg = Xcg aft
+10 deg
-0.4
-0.6
CL
4
4.5
Control Forces
• Used Roskam methods to determine
control forces
• Analysis shows that FAR 23 stick force
limits are satisfied
Control Forces vs. Control Deflections in Cruise
120
100
Force (N)
80
Ailerons
Rudder
Elevators
60
40
20
0
0
1
2
3
4
Deflections (deg)
5
6
7
CG Excursion Graph
650
MTOM
Configuration Mass [kg]
600
Heavy Pilot
Front Pilot Only
MTOM with
6% fuel
550
Rear Pilot Only
500
450
400
Stability limits
OEM
Landing Gear limits
350
1.70
1.80
1.90
2.00
2.10
2.20
CG Position From Wing Apex [m]
2.30
2.40
CG Travel in MTOM Flight
1.9
Taxi
T.O.
Climb
CG position from apex (m)
1.88
1.86
1.84
1.82
Cruise
Descent
Land
1.8
0
1
2
3
4
5
Flight Segment
Conclusion: Stable Aircraft
6
7
The Rand Cam Engine
• Innovative diesel rotary engine
• Inherently simple, no pistons, timing values,
spark plugs
• Uses a system of axial vanes that rotate in a
cam shaped housing
The Rand Cam Engine
• Light weight – High power to weight ratio
• Fuel efficient
• Costs similar to that of an equivalent
automotive engine
• Low noise
• Very little vibration
• Low maintenance
Engine Layout
Engine
Starter
Exhaust
Pipes
Alternator
Cooling Air
Exhaust
Intake
Cooling
Fan
Intake Plenum
Oil Pump
Fuel Tank
Cooling Air
Intake
Oil Cooler
Oil Tank
Ducted Fans
• Higher thrust per horsepower for a given
diameter than a propeller
• Better performance at low speeds than
propellers – no recirculation at the tips
• Quieter than propellers – noise damping
material used in ducts
• Duct provides an additional safety feature.
• Duct diameter 0.92 m (3 ft)
• Fan consists of 5 rotor blades and 12 stator
blades
• Fans attached to engine via a 1:2 helical
spiral bevel gear
• Low noise 60dBs. Tip speed 113 m/s (370
ft/s)
Thrust Calculations
•
Static thrust calculated using disc actuator
theory

TS  P 2A
•

2/3
Dynamic thrust found using general thrust
equation
P
T
V
•
Efficiency found by reading from chart of
empirical data charts
Thrust Curve
5000
General thrust
equation
Disc actuator
theory
Thrust (N)
4000
3000
2000
1000
0
0
50
100
Airspeed (knots)
150
Cockpit Layout
Cockpit
• Designed for 95th percentile male
(tallest male) and adjustable to 5th
percentile female (shortest female)
• Adjustable seats and rudders
• Center stick
• Energy absorbing Confor™ foam
seats for high impact landing
• Canopy door allows ease of entrance
• Harness seatbelts for pilot and
passenger safety
Avionics
• Base Cockpit Instrumentation:
• EFIS:
• Display
• EFIS Computer
• AHRS Computer
• PFD & Engine instrumentation
• Transmission & Reception devices:
• NAV/COMM Radio
• Mode A/C Transponder
Avionics
PRIMARY FLIGHT DISPLAYS
AND ENGINE INSTRUMENTS
EFIS DISPLAY
TRANSMISSION & RECEPTION EQUIPMENT
Systems
• Safety
• Anti-lock brakes
• Ballistic parachute
• 5 Point seat belt
• Control surface actuation
• Mechanical
• Canopy
• Single piece with gas struts
Systems
• Cabin Conditioning
• Warm air taken from oil cooler
• Mixed with external air
• Provides de-misting (de-frosting)
• Electrical
• Standard 28V system
• 120 Ampere alternator
Landing Issues
• Original Specification – 46m (150ft)
landing distance over 5m obstacle
5m
7o
46m
150ft
5m
14m
46ft
9o
If stall speed = 25kts
and free roll = 1 second
free Roll = 15m
Revised Specifications
• Target ground roll – 46m (150ft)
• Total landing and take off – NASA SSTOL
DEFINITION
LANDING DISTANCE
OVER 50ft OBSTACLE
CTOL
2000ft
STOL
1000ft
SSTOL
500ft
VTOL
100 ft
• 9o Glideslope used in NASA analysis
Landing and Take-off
Ground Roll (m)
Ground Roll
60
55
50 Target
45
40
35
30
25
20
4000
4500
Landing
Take-off
5000
5500
6000
6500
Take-off weight (N)
• Target met at all take-off weights
• Landing Target met with 1 pilot and full fuel
Landing and Take-off
• Certification over 50ft (15m) obstacle
Ground Roll
Ground Roll (m)
155
150
Target
145
140
Landing
135
130
Take-off
125
120
4000
4500
5000
5500
6000
Take-off weight (N)
• SSTOL requirement met at all conditions
6500
Cruise Performance
Range at different Cruise Speed 10Kft
800
700
Range (nm)
600
500
400
300
200
MTOW
100
1 Pax Full
Fuel
0
0
20
40
60
80
100
120
140
Speed (knots)
• Max Range Full Payload 650nm @ 80 knots
• 500 nm @ 124 knots
• Max Endurance over 8 hours @ 64 Knots
160
Climb Performance
Climb Rate at Cruise speed and Throttle Settings
1600
100%
1400
90%
80%
Climb Rate (ft/min)
1200
70%
50%
1000
60%
800
600
400
200
0
38
58
78
98
118
138
158
Speed (Knots)
• 10,000 ft in under 10min @ 85 % and 90 Knots
• Max Climb 1364 ft/min @ 90 Knots
Turn Rates
Turn Rate Curve @ 1000 ft
80
n=4
Corner Speed @ 57
knots
n=3
70
n=2
Turn Rate (deg/sec)
60
Structural
Limit n = 3.8
n=1.5
50
40
Stall Limit
30
20
10
0
0
20
40
60
80
100
Velocity (knots)
• Max Turn Rate 70 Deg/sec @ 57 knots
120
140
Mass Breakdown
kg
Structure 235
Propulsion 112
Equipment 28
OEM 375
lb
486
246
62
794
%
37
18
4
59
Payload
Fuel
182
78
400
172
29
12
MTOM
635
1366
100
Aircraft Cost Analysis
• Target price – luxury sports car
• US $200,000 price ceiling
• Costing analysis is conducted using Roskam
methods
• Anticipated cost reductions from avionics
development are not yet considered
Certification Philosophy
• Certify under Joint Airworthiness Requirements
Very Light Aircraft Category
• Federal Airworthiness Requirements
Sport aviation category:
Revise requirements
Strengths
Cruise Speed
Storch
Zenith CH701
Jabiru
Slingsby Firefly
Cessna 172
Ikelos
Mission M212
Europa XS
Aeris 200
40
60
80
100
120
Cruise Speed (kts)
140
160
Strengths
Landing Ground Roll
Slingsby Firefly
Aeris 200
Mission M212
Europa XS
Cessna 172
Jabiru
Ikelos
Zenith CH701
Storch
0
100
200
300
Landing Ground Roll (m)
400
Weaknesses and Threats
• Risk – Unproven propulsion system
• Control authority in landing – more analysis
required
• Specialized product for SSTOL market.
Opportunities
Range of aircraft – basic to high performance
High performance options:
• More advanced avionics
• Thrust vectoring
• Circulation control
• Higher end of Market
• Military or law enforcement possibilities
Conclusions
• Innovative modern technology employed.
• Large scope for adaptability
• Configuration set – but still opportunity for
adjustments
• Project still in progress