Download SURFACES Design Powerpoint Demo - 2.5 Mb

New Piper Aircraft Jet
The following is an example of how Surfaces can be used to analyze an
aircraft from little more than a low quality drawing copied from a
brochure.
The following is for demonstration purposes only and may not represent actual data.
What will be Covered…
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Why should you care?
What is SURFACES?
Model Creation
Validation Samples
Examples of Aerodynamic Analysis
Examples of Aerodynamic Loads
Examples of Stability and Control
Approximate length – 1 hour.
Why should you care?
• Fast and reliable estimation of aerodynamic
properties.
• Fast and reliable estimation of stability derivatives.
• Fast and reliable estimation of aerodynamic loads.
• Fast “what if” evaluation of configurations (T-tail
versus Conventional tail versus H-tail versus…).
• Ideal for sensitivity studies.
• Tailoring of stall progression.
• Control effectiveness studies.
• and more…
What is SURFACES?
• Interactive environment that allows the user to design
and analyze aircraft geometries.
• SURFACES has a multi-document interface.
• In SURFACES you do everything in a single program;
pre-process, solve, and post-process.
• SURACES uses two kind of documents; a Surfaces
Worksheet and an Aircraft Datasheet.
What is SURFACES?
• Interactive environment that allows the user to design
and analyze aircraft geometries.
• SURFACES has a multi-document interface.
• In SURFACES you do everything in a single program;
pre-process, solve, and post-process.
• SURACES uses two kind of documents; a Surfaces
Worksheet and an Aircraft Datasheet.
A SURFACES Worksheet is your digital wind tunnel.
A SURFACES Aircraft Datasheet is where stability
and control and performance analysis takes place.
What is SURFACES?
Model Details
What is SURFACES?
Model Details
What is SURFACES?
Model Details
Movable
control
surfaces
Forces and Moments
can be applied using
equations
Movable
flaps
Flow Solver
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Three dimensional Vortex-Lattice Method is used to
determine the flow field.
Models can be symmetric as well as asymmetric.
Boundary conditions allow AOA and AOY.
Three compressibility models (Prandtl-Glauert, KarmanTsien, Laitone)
Three induced drag models (surface integration,
standard Cdo+k∙CL², and Prandtl-Betz).
Program can take advantage of multiple processors on
the motherboard and solve more than one model
simultaneously.
Validation Sample 1
Pressure distribution over a flat plate.
CP versus Chord Station for a Flat Plate
5.00
Exact Theory
4.50
Cp from Surfaces, N=2
4.00
Cp from Surfaces, N=5
Cp from Surfaces, N=10
Pressure Coefficient,  CP
3.50
Cp from Surfaces, N=15
3.00
2.50
2.00
1.50
1.00
0.50
0.00
0.00
0.20
0.40
0.60
Chordwise Station
0.80
1.00
Validation Sample 9
NACA R-1208 – Comparison to Wind Tunnel Tests
Highly swept-back tapered wings are a good test for any code.
Validation Sample 9
NACA R-1208 – Results from SURFACES
Section Lift Coefficients from NACA R-1208
1.2
1
Cl·C/CL·Cmean
0.8
NACA R-1208 DATA at 4.7°
SURFACES RESULTS at 4.7° (16 spanwise panels)
SURFACES RESULTS at 4.7° (32 spanwise panels)
0.6
SURFACES RESULTS at 4.7° (64 spanwise panels)
0.4
0.2
0
0
0.1
0.2
0.3
0.4
0.5
0.6
Spanwise station, 2y/b
0.7
0.8
0.9
1
Examples of Aerodynamic Analysis
Examples of Aerodynamic Analysis
Examples of Aerodynamic Analysis
What We Don’t Know about the Piperjet
• Airfoils and airfoil properties
• Winglet geometry
• CG Envelope
• FJ44 Thrust properties
• Gross Weight / Inertias
• Ram drag point location
• True Geometry in many areas
• Flap definition
• Wing washout
• Wing dihedral
• Aileron and elevator geometry
• FAA Design speeds
Examples of Stability and Control
Angle-of-Attack Derivatives
Approach
Cruise
Vfar field
134
591
Basic lift coefficient
CLo
0.8518
0.1277
Lift coefficient
CL
1.3242
0.15201
Lift curve slope
CLa
5.0388
6.21135
Drag coefficient slope
CDa
1.7705
0.11453
FX variation with AOA
Cxa
0.0659
0.06183
FZ variation with AOA
Cza
-5.467
-6.219
CG location
Xcg
0.2000
0.2000
Neutral point (Xcg-Cma/CLa)
Xneu
0.4936
0.4566
Far field speed
Examples of Stability and Control
Angle-of-Yaw Derivatives
Approach
Cruise
Vfar field
134
591
Side force derivative
Cyb
-1.3417
-1.26053
Dihedral Effect
Clb
-0.1427
-0.15177
Directional Stability
Cnb
0.1266
0.14048
Far field speed
Examples of Aerodynamic Analysis
Stall Progression
At S-L, 5000 lbs, 75 KEAS, Flaps UP, no yaw.
Examples of Aerodynamic Analysis
Compliance with FAR 23.77(c) at Forward CG
At S-L, 5500 lbs, CG at 20% MAC, VREF=79 KEAS
atrim = 5.37°
detrim = -17.3°
Examples of Aerodynamic Analysis
Compliance with FAR 23.77(c) at Forward CG
At S-L, 5500 lbs, CG at 20% MAC, VREF=79 KEAS
Minimum
section lift
coefficient,
CL2D = -1.003
Conclusions
• SURFACES
–Model Creation
–Flow Solver
–Validation Samples
• The Piper Jet
–Examples of Aerodynamic Analysis
–Examples of Aerodynamic Loads
–Examples of Stability and Control
The End
• Feedback
– Questions
– Comments
Validation Sample 5
Cessna 172 - Comparison to Flight Test results.
When compared to 3
other VL codes and
the panel code
CMARC, SURFACES
scores highest when
determining stability
derivatives.
Examples of Aerodynamic Analysis
Trim Drag in Cruise
At 25000 ft, at 5500 lbs, 350 KTAS, CDo= 0.020, Prandtl-Glauert compressibility
CG Location
20% MAC
35% MAC
atrim
0.22°
0.13°
detrim
-1.25°
-0.35°
CLtrim
0.1520
0.1520
CDtrim
0.0276
0.0273
Drag, lbf
1000
988
Vtrim, KTAS
348
350
Examples of Aerodynamic Load Analysis
Shear Diagram at VA
At S-L, 6000 lbs, CG at 20% MAC, VA= 152 KEAS
Examples of Aerodynamic Load Analysis
Moment Diagram at VA
At S-L, 6000 lbs, CG at 20% MAC, VA= 152 KEAS
Examples of Aerodynamic Load Analysis
Torsion Diagram at VA
At S-L, 6000 lbs, CG at 20% MAC, VA= 152 KEAS
Examples of Aerodynamic Analysis
Flow Visualization - Streamlines
Sweep Scripts
SURFACES can perform
sweeps, during which
selected parameters can
be modified.
AOA, AOY, p∙b/(2V), and
others can be varied and
studied.
Points can even be
moved during a sweep
Sweep Scripts
Once a sweep script is
completed, are displayed
in a tabular format,…
Sweep Scripts
…or a graph, in which any
parameter can be plotted
against each other.
This allows the user to
extract relationships as
mathematical expressions.
Sweep Scripts
From time to time, many
sweeps may have to be
created.
You can set up batch
processing, which will
handle the processing
automatically.
This allows the program to
be run overnight or over a
weekend.