Matlab/Simulink Tools for
Teaching Flight Control
Conceptual Design:
An Integrated Approach
Hanyo Vera Anders
Tomas Melin
Arthur Rizzi
The Royal Institute of Technology, Sweden.
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Presentation Outline
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Computer Tools for Preliminary Aircraft Design
QCARD Conceptual Design Tool
Tornado Vortex Lattice Method
CIFCAD Flight Simulator
Case study: Student Project for Conceptual Design.
Questions-Comments
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Problems on Preliminary
Aircraft Design
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The simplified methods used in the early phases of design do not
give sufficient fidelity, which may result in mistakes which are
costly to correct later in the design cycle.
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Some examples pertaining to the Flight Control System are:
DC-9: unexpected pitch-up and deep stall of T-tail lead to
costly redesign
DC-9-50 & MD-80: inadequate directional stiffness at high
angles of attack in sideslip; adoption of low-set nose strakes
SAAB2000: larger than expected wheel forces caused delay in
certification; costly redesign of control system
Boeing 777: missed horizontal tail effectiveness led to larger
than needed horizontal tail
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Computer Tools for
Preliminary Aircraft Design
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There is work going on into the development of Computer
Tools to facilitate the preliminary aircraft design process:
• QCARD
• Tornado
• SIFCAD Flight Simulator
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QCARD:
Quick Conceptual Aircraft
Research & Development
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QCARD in the Conceptual Design Process
Design Requirements
Business Case & Objectives
Airworthiness
Aircraft Morphology, Integration & Optimisation
Geometry
Geometry
Sizing
Sizing &&
Positioning
Positioning
of
ofEmpennage
Empennage
Sizing,
Sizing,
Positioning
Positioning&&
Deflection
Deflection
of
ofSurfaces
Surfaces
Structures
Structures
Weights
Weights&&
Balance
Balance
Aerodynamics
Aerodynamics
Propulsion
Propulsion
Flight
FlightControl
Control
System
System
Mech/Elec
Mech/Elec
Systems,
Systems,
Avionics
Avionics &&
Interiors
Interiors
Loads
Loads
Loadability
Loadability&&
Stability
Stability
Margins
Margins
High-Lift
High-Lift
Design
Design
Philosophy
Philosophy
Control
Control
Augmentation
Augmentation
due
due to
to Thrust
Thrust
Vectoring
Vectoring
System
SystemModes
Modes
&&Failure
Failure
Modes
Modes
Ice
IceProtection
Protection
Philosophy
Philosophy
Low-speed
Low-speed&&
High-speed
High-speed
Design
Design
Philosophy
Philosophy
Control
Control Laws
Laws &&
Protection
Protection
Functions
Functions
Longitudinal,
Longitudinal,Lateral
Lateral &&
Directional
Directional Static-Dynamic
Static-Dynamic
Stability
Stability&&Control
Control
Operational
Operational
Performance
Performance &&
Economics
Economics
Noise
Noise&&
Emissions
Emissions
Critical assumptions made for
sub-categories generates
cross-disciplinary interaction
at primary and secondary
levels
Controllability & Manoeuvrability
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Core Simulation
Modules
CAD geometry
data
Iteration loop/feedback on design
Mesh
generation
Each partners’
CFD solver
with
moving mesh
capabilities
Flight state:
•Motion and
altitude
•Trajectory
Control surface
state:
•Position and
motion
QCARD core:
Comp Static/Dyn
Derivativ, limited
Aeroelast, buffet
effects
QCARD analyzer
•Stability margin
•Empennage/
con sur. sizing
•S&C modes,
damping modes
ControllabilityManeuverability
• Control surface
effectiveness
• Handling
qualities
• Pilot work load
• etc
QCARD Environment Modules
KTH working on two topics today:
• Tornado (Dynamic Derivatives)
• SIFCAD
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Conceptual Prediction
Methods: Stability & Control
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This discipline has lacked any form of sophistication & depth at
the conceptual level
– fundamental issues: controllability & manoeuvrability
– tail volume method was adequate in the past; today, critical
scenarios need to be identified & addressed early on
Introduction of the Mitchell Code during sizing
– original ICL FORTRAN code now converted to MATLAB
– estimates: aero derivatives, moments of inertia, eigenvalues
of motion equations, forced response and limiting speeds
Assessing the suitability of design candidates
– avoidance of esoteric figures of merit for uninitiated
– extensive use of Cooper-Harper scale correlated with merit
function plots, i.e. ESDU, MIL-Spec, ICAO, SAE, etc.
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Sub-space Coupling &
Process Logic
until minimum
goals achieved
Weights
Geometry
Performance
Stability &
Control
Propulsion
Aerodyn.
until minimum
goals achieved
DOC/P-ROI
& Optimal
Techniques
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Aerodynamic Coefficients:
TORNADO
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Developed by Tomas Melin,
KTH.
Vortex-Lattice Method.
Implemented in Matlab
Allows the analysis of complex
geometry wings (swept, tapper,
dihedral, tails,...)
Different Flying Condition
(Angles of Attack and Sideslip
Angles, Roll, Tip and Yaw
velocities)
For wing-configuration, good
results with projection of body
along x-z and x-y planes.
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TORNADO:
Basic Assumption-Potential Flow
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Inviscous
Incompressible
Irrotational
Existence of
Velocity potential
∇ × ∇φ = 0
∇ φ =0
2
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Tornado Implementation
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Sample Output
Tornado Computation Results
ilona3
JID:
Downwash matrix condition: 870034.5925
Reference area: 74.6078
Reference chord: 2.8041
Reference point pos:
2.8583
0
Reference span: 30.16
Net Wind Forces: (N)
Drag: 3859.3759
Side: 35533.5133
Lift: 291384.6908
Net Body Forces: (N)
X: -9538.6779
Y: 35533.5133
Z: 291284.6705
Delta cp distribution
0.58619
0
Net Body Moments: (Nm)
Roll: 371527.6714
Pitch: -244497.527
Yaw: 516493.7084
-0.5
CL
CD
CY
0.2834
0.0037536
0.034559
CZ
CX
CC
0.2833
-0.0092772
0.034559
Cm
Cn
Cl
-0.084803
0.016656
0.011981
-10
-5
STATE:
alpha:
beta:
Airspeed:
Density:
3
0
150
1.225
P:
Q:
R:
0
0
0
0
0
Rudder setting [deg]: 0
0
0
0
0
0
0
0
5
0
5
0
4
0
30
0
0
0
0
0
-1
0
5
-1.5
2
1
10
0
-10
15
-5
-2
0
5
10
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SIFCAD Flight Simulator
0.01
• OBJECTIVES:
-K-
Aileron1
0
Aileron_Com
Flap
0.5
States
-K-
Elevator
Terminator
0.5
Controls
Rudder1
VelW
-K-
-0.7
R2D
Airspeed
R2D
Mach
0
Sideslip
Euler
-1
• Flight Control System
Design.
- Analysis of Handling
Qualities.
- Assessment of Mission
Profile.
m
Ang Acc
Rudder_Com
Throttle1
0
Sensors
Elev_Com
Winds
0
AeroCoeff
Mass
Throttle_Com
AOA
ECEF
0
MSL
Bank angle
AGL
Axes
RST
Buttons
joyinput
R2D
REarth
0
m
AConGnd
Pitch angle
STOP
Point of View
Aerosonde UAV
Joystick Input
Axes
0
Stop Simulation
when A/C on the ground
Heading
m
Bank-angle to ailerons PI control
0
-K-
Auto_Aileron
Bank-angle-to-Aileron
Proportional
0
-KAuto_Elev
0
0
Modifications:
- Instalation of Turbofan Engine
List of Blocksets:
- Aerosim Blocket
- Virtual Reality Toolbox
- Aerospace Blockset
Airspeed
Bank angle
Command
FS Interface
RAD DEG
Airspeed to elevator PID control
RTCsim
-K-
Aileron
Euler
0
Bank-angle-to-Aileron Bank angle
Integral
Integrator
rad 2 deg
Elev
Position
1
s
RAD DEG
rad 2 deg1
Airspeed-to-Elevator
Proportional
-K-
Time Error in msec
Real Time Control
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1
s
Airspeed
Command
-KGain
Simulation Time in sec
Airspeed-to-Elevator Airspeed error
Integral
Integrator
-K-
du/dt
Simulation sample time 10 ms
Simulation time: 5 min.
Airspeed-to-Elevator Airspeed error
Derivative
Derivative
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SIFCAD: Characteristics
• Flight Simulator in
Simulink Environment
• Based on commercially
available Simulink
Toolboxes
• Graphics provided by
Microsoft Flight Simulator
• Highly Flexible and easily
customable (Simulink
format)
• Options: Fast-time or
Real-time.
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Simulink Toolboxes:
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Aerospace Blockset - Mathworks
- Aerodynamic
- Engine,
- Earth and Atmosphere models.
Virtual Reality Toolbox Mathworks
- Man-Machine interface i.e.
Joysticks)
AeroSim Blockset – Unmanned
Dynamics
- Aerodynamic,
- Engine,
- Earth and Atmosphere models
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Simulink Toolboxes:
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Flight Dynamic and Control
Blocket
- M.O. Rauw, Netherlands.
- Aerodynamic,
- Engine,
- Earth and Atmosphere
models
- Avionics.
Port and Memory IO for
Matlab and Simulink –
Werner Zimmermann, FHT
Esslingen
- Real time execution in
Matlab Environment.
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Interface with Microsoft Flight
Simulator
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Use of interface provided by
AeroSim Blockset
Possibility to send
information to a Second
Computer Running Microsoft
Flight Simulator
Information sent involves
position, attitude and gauges
information.
The result is high quality
graphic interface without the
need of extensive
programming.
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Use of Simulator
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Simulator Running at FastTime:
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Airplane Model
development
FCS development and
testing
Autpilot testing
Mission profile Assesment
Real Time Simulation:
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Handling Qualities
Assesment
Pilot-in-the-loop analysis
Research in Aircraft
Operational Factors
Research in Human
Factors.
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Case Study: Horizon Project
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Conceptual Design
Student Project in The
Royal Institute of
Technology in
collaboration with Ecole
Polytechnique of
Montréal
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Objective:
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Analysis of 70 PAX
regional airliner
Unducted Fan
Able to achieve speeds
close to Turbofan
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Case Study: Horizon Project
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Procedure: Use of QCARD in the
conceptual design process:
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Estimation of Low Speed
Aerodynamic Properties
Estimation of High Speed
Aerodynamic Properties
Stability and Control Analysis
Conclusion: The initial design has
poor stability qualities. Need to
improve the design to reach
reasonable stability characteristics.
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Geometric Modifications
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Wing:
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Horizontal Tail:
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Moved Forward
Increased Area
Reduced Aspect Ratio
Lowered
Increased Area
Increaed Aspect Ratio
Vertical Tail:
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Reduced Area.
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Results of the Modifications
Type of
motion
Name
Period (s)
Time-to-half
(s)
Cycles-to-half
Initial
Impro
ved
Initial
Impr
oved
Initial
Impro
ved
Phugoid
1.76e5
1.81e6
94.98
95.9
5.4e-4
5.3e-4
Short-period
4.35
2.92
0.82
0.58
0.19
0.20
Dutch roll
5.11
5.40
12.94
6.84
2.52
1.26
Spiral
128.4
117.5
Rolling
convergence
0.86
0.89
Longitudinal
Lateral
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Stability and Control Analysis
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Stability and Control Analysis
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Stability and Control Analysis
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Stability and Control Analysis
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Possibilities of using SIFCAD in
Horizon Project
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Higher understanding of
criteria for stability.
Analysis of airplane handling
with Pilot-in-the-loop.
Possibilities of considering
relaxed stability in design.
Design of Flight Control
Systems.
Mission Profile Analysis.
Response to medium and
heavy weather phenomen (i.e.
Gusts, windshear, etc.)
Explore operational profile
(take-off, approach, landing)
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SIFCAD Demo:
Horizon Model
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SIFCAD: Future Goals
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SIFCAD in Aeronautic
Education
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Teach to student effects of
changes in Aerodynamic
Coefficients in Airplane
Handling
Effects of Center of Gravity
in Aerodynamic Stability.
Suitable for teaching
Concepts on Flight Control
System Design
Suitable for practical
examples in Avionics use
and Limitations.
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SIFCAD: Future Goals
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Full Integration with QCARD
software:
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Automatic Load of
Aerodynamic, engine and
mass properties onto the
Simulator Model.
Requisite for integration on
the Conceptual Design
package.
Use in research:
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Airplane Design
Operations
Human Factor
Etc.
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SIFCAD: Ongoing and Future
Work.
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Improve the Aerodynamic Model
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Possibility to manage non-linear aerodynamic phenomena.
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Develop a stable simulation platform with ”best of
commercial packages” plus native development.
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Improve Human-Machine interface:
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Projectors
Glass-Cockpit
Improved Joysticks
Pedals
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Questions – Comments?
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