1 VSP Workshop 2019 OpenVSP Parasite Drag Build Up

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NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2020 Sept. 15th – Sept. 17thEmpirical Systems Aerospace, Inc. www.esaero.com

VSP Workshop 2019

OpenVSP – Parasite Drag Build Up

Presented by:

Nick Brake

Empirical Systems Aerospace, Inc.

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Objectives

• Reduce the time it takes to

complete a parasitic build

up

• Increase geometry fidelity

over workbook-only

methods

• Provide validation artifacts

to build confidence

• Scriptable for design

exploration & trades

Faster, More Accessible

Improved Geometry fidelity

Validation

Scriptable

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Approach

• Uses existing geometry, equations for friction coefficient, form factor

equations, and flow conditions to create a full parasitic drag build up

of the selected components

– Plethora of options for calculated friction coefficient and calculated form factor

– Manually set freestream flow parameters or use a standard atmosphere model

• Export data to organized CSV file

• Provide documentation & validation cases for implementation

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GUI Overview – Global Settings

• Geometry units

• Lam/Turb Cf equation selection

• Reference area

• Atmospheric & flow conditions

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GUI Overview – Build Up Table

• Table of geometry & sub surfaces

• Sortable by: “Component”, “S_wet”,

“% Total”

• User selection of Group Treatment

• User selection of FF equation

• User settable % Laminar

• User settable Q – Interference

Factor

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GUI Overview – Excrescence Tab

• Allows specification of additional

drag– Drag Counts, or CD

– Drag Area D/q

– % CD of Geom, % Margin

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GUI Overview – Documentation Tab

• Reference symbol and abbreviation definitions

• Quick link to Wiki website

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Friction Coefficient Equations Used

• Laminar:– Blasius

• Turbulent:– “Fluid-Dynamic Drag” by S. F. Hoerner

• Prandtl-Karman

• Approximate Schoenherr

• Intrinsic Schoenherr

• Schultz-Grunow 1

– “A Simple New Analysis of Compressible Turbulent Two-Dimensional Skin Friction Under

Arbitrary Conditions” by F. M. White and G. H. Christoph• Schultz-Grunow 2

• Blasius Power Law

• Intrinsic Von-Karman

• Prandtl-Schlichting

• White-Christoph Best Fit

• White-Christoph w/ Heat Transfer

– “Viscous Fluid Flow” by Frank M. White• White Power Law

• Prandtl Power Law

• ‘Exact’ Solution

• White w/ Roughness

• Schlichting w/ Roughness

– “Thrust and Drag: Its Prediction and Verification” by Eugene E. Covert• Intrinsic Karman-Schoenherr

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Friction Coefficient Equations Used

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Form Factor Equations Used

• Wing:

– “Zero Lift Drag and Drag Divergence Prediction for Finite Wings in Aircraft

Design” – AIAA Paper• EDET Conventional

• EDET Advanced

• DATCOM

• Hoerner

• Williams

• Kroo

• Torenbeek

– “Thrust and Drag: Its Prediction and Verification” by Eugene E. Covert• Covert

• Body:

– “Thrust and Drag: Its Prediction and Verification” by Eugene E. Covert• Covert Body

• Covert Nacelle

– “Fluid Dynamic Drag” by S.F. Hoerner• Hoerner Streamlined

– “Synthesis of Subsonic Airplane Design” by E. Torenbeek• Torenbeek

• Shevell

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Form Factor Equations

• Wing:

• Body:

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Geometry Alignment

• Tool assumes geometry is aligned with the

flow direction

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Order of Operations

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Add and Edit Geoms

Edit Options as Desired

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Order of Operations – Cont.

2a 2bAdd Excrescence Edit Excrescence

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3

Options as Desired

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Calculate CD0 or Export to CSV

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• Use scrollbar or expand

window to see rest of

data

• Press “Export to CSV” to

output the data into an

organized CSV file

• Changes to Freestream

properties can be

changed from here to

witness changes to Cd0

• If Geoms are added,

everything is cleared and

must calculate again

Final Results5

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DEMO – Simple Plane

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Validation – Lockheed S-3A Viking

• Aircraft: Lockheed S-3A Viking

• Technical report provides traditional

component-based build-up

• Drag values developed from “>5,000hrs” of

wind tunnel testing

Model Available on VSP Hanger:

http://hangar.openvsp.org/vspfiles/466

References:

Technical Report: Durrie, J. E., “S-3A Basic

Aerodynamic Data Report,” Lockheed-

California Company, LR 22815, Sep. 1970.

Aircraft Dimensions: NAVAIR, “Standard

Aircraft Characteristics Navy Model S-3A

Aircraft”, NAVAIR 00-110AS3-1, January 1973

Airfoils: Lednicer, David. "The Incomplete

Guide to Airfoil Usage". m-selig.ae.illinois.edu.

Retrieved September 2020.


https://m-selig.ae.illinois.edu/ads/aircraft.html

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VSP Modeling

• Approximated from 3-view

• Cowl modeled as a • ‘BOR’ → Horner

• ‘Duct’ → Jenkinson Wing Nacelle

Updates Since 2019 Workshop

• Updated airfoils • Root Airfoil NACA0016

• Tip Airfoil: NACA 0012

• Adjusted layout to better match images • H-Tail height

• Wing dihedral

• Added Aft nacelle & wing pylon

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• Engine Nacelles modeled

with zero drag interior flow

path

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Validation and Verification. - BOR

f (ft^2) Cd % Total Cd (Ref.) % diff

% error

of Total

10.651485 0.017801 94% 0.01993 -11% -10%

0.688128 0.00115 6% 0.00115 0% 0%

11.339613 0.018951 100% 0.02108 -10% -10%

Geometry Sub-Total:

Excrescence Sub-Total:

Totals:

Mach Altitude (ft) Vinf (Mach) S_ref (ft^2)

0.649737 40000 0.649737 598.3719

Temp (F) Pressure (lbf/ft^2) Density (slug/ft^3)

-69.7 391.683791 0.000585

Lam Cf Eqn Turb Cf Eqn

Laminar Blasius Compressible Schlichting

Component Name S_wet (ft^2) L_ref (ft) t/c or d/l FF FF Eqn Type Re % Lam Cf

Q (Interference

Factor) f (ft^2) Cd % Total Cd (Ref.) % diff

% error

of Total

Fuse 963.940772 49.473492 5.922892 1.137751 Hoerner Streamlined Body 61324748.25 0 0.002281 1 2.501973 0.004181 22% 0.00524 -20% -5%

Wing 1070.100067 9.73791 0.159925 1.359097 Hoerner 12070603.46 0 0.002915 1 4.239618 0.007085 37% 0.00808 -12% -5%

Nacelle Pylon 74.731693 10.165959 0.080022 1.162505 Hoerner 12601190.33 0 0.002895 1 0.251536 0.00042 2% 0.00034 24% 0%

[B] Cowl TOTAL 293.30374 1.039293 0.001737 0% 0.00158 10% 1%

Cowl_BypBOR 123.639047 5 0.119982 1.252398 Hoerner 6197738.011 0 0.003247 1 0.502709 0.00084 4%

Cowl_AftBOR 169.664693 9.5 0.040257 1.080671 Hoerner 11775702.22 0 0.002927 1 0.536584 0.000897 5%

Wing Store Pylon 80.599842 7.663647 0.055013 1.110576 Hoerner 9499454.683 0 0.003029 1 0.271092 0.000453 2% 0.00117 -61% -3%

H-Tail 346.450415 6.920658 0.120003 1.252449 Hoerner 8578485.573 0 0.003079 1 1.335886 0.002233 12% 0.00203 10% 1%

V-Tail 284.410228 11.440942 0.119861 1.252107 Hoerner 14181592.28 0 0.002842 1 1.012088 0.001691 9% 0.00149 13% 1%

Excrescences Type Input

Misc CD 0.00085 0.508616 0.00085 4% 0.00085 0% 0%

Cowl Boattail CD 0.0003 0.179512 0.0003 2% 0.0003 0% 0%

10.651485 0.017801 94% 0.01993 -11% -10%

0.688128 0.00115 6% 0.00115 0% 0%

11.339613 0.018951 100% 0.02108 -10% -10%

PARASITE DRAG BUILD UP DATA

Geometry Sub-Total:


Totals:

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Mach Altitude (ft) Vinf (Mach) S_ref (ft^2)

0.649737 40000 0.649737 598.3719

Temp (F) Pressure (lbf/ft^2) Density (slug/ft^3)

-69.7 391.683791 0.000585

Lam Cf Eqn Turb Cf Eqn

Laminar Blasius Compressible Schlichting

Component Name S_wet (ft^2) L_ref (ft) t/c or d/l FF FF Eqn Type Re % Lam Cf

Q (Interference

Factor) f (ft^2) Cd % Total Cd (Ref.) % diff

% error

of Total

Fuse 963.940772 49.473492 5.922892 1.137751 Hoerner Streamlined Body 61324748.25 0 0.002281 1 2.501973 0.004181 22% 0.00524 -20% -5%

Wing 1070.100067 9.73791 0.159925 1.359097 Hoerner 12070603.46 0 0.002915 1 4.239618 0.007085 37% 0.00808 -12% -5%

Nacelle Pylon 74.698032 10.165959 0.080022 1.162505 Hoerner 12601190.33 0 0.002895 1 0.251422 0.00042 2% 0.00034 24% 0%

[B] Cowl TOTAL 293.928979 1.124781 0.00188 10% 0.00158 19% 1%

[B] Cowl_BypDuct 123.855085 5 3.104489 1.25 Jenkinson Wing Nacelle 6197738.011 0 0.003247 1 0.502623 0.00084 4%

[B] Cowl_AftDuct 170.073894 9.5 5.379271 1.25 Jenkinson Wing Nacelle 11775702.22 0 0.002927 1 0.622158 0.00104 5%

Wing Store Pylon 80.599842 7.663647 0.055013 1.110576 Hoerner 9499454.683 0 0.003029 1 0.271092 0.000453 2% 0.00117 -61% -3%

H-Tail 346.450415 6.920658 0.120003 1.252449 Hoerner 8578485.573 0 0.003079 1 1.335886 0.002233 12% 0.00203 10% 1%

V-Tail 284.410228 11.440942 0.119861 1.252107 Hoerner 14181592.28 0 0.002842 1 1.012088 0.001691 9% 0.00149 13% 1%

Excrescences Type Input

Misc CD 0.00085 0.508616 0.00085 4% 0.00085 0% 0%

Cowl Boattail CD 0.0003 0.179512 0.0003 2% 0.0003 0% 0%

10.73686 0.017943 94% 0.01993 -10% -9%

0.688128 0.00115 6% 0.00115 0% 0%

11.424987 0.019093 100% 0.02108 -9% -9% Totals:


Geometry Sub-Total:

PARASITE DRAG BUILD UP DATA

Validation and Verification. - DUCT

f (ft^2) Cd % Total Cd (Ref.) % diff

% error

of Total

10.73686 0.017943 94% 0.01993 -10% -9%

0.688128 0.00115 6% 0.00115 0% 0%

11.424987 0.019093 100% 0.02108 -9% -9% Totals:


Geometry Sub-Total:

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• Available on VSP Hanger

• http://hangar.openvsp.org/vspfiles/466


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DEMO – S-3A

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API/Scripting Integration

• S-3 Viking Script Included with public release

– Example of how to change parameters and run Parasite

Drag analysis

• User has full access to all UI inputs through API

– All general options can be called through enumerators

(e.g. CF_TURB_IMPLICIT_KARMAN_SCHOENHERR)

– All table row inputs are found through the parent

geometry

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Unit Tests and Visual Output

• Simple model

creation, analysis run,

option changes are all

tested through the

API

• S-3 Viking Model also

included as test

• All equation data

output to *.csv to be

tested by included

Matlab script

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Documentation

• Basic UI and usability

documentation within the

Parasite Drag Tool

• Reference length calculation

methods (body/wing)

• Partial turbulence friction

coefficient method

• Grouping

• Subsurface handling

• All friction coefficient and form

factor equations listed on wiki,

references included

• Visualization of data pulled

from unit tests

http://openvsp.org/wiki/doku.php?id=parasitedrag

http://openvsp.org/wiki/doku.php?id=parasitedrag

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Contact Information

Nick Brake

[email protected]

ESAero

[email protected]

mailto:[email protected]

mailto:[email protected]

Documents

1 VSP Workshop 2019 OpenVSP Parasite Drag Build Up