Nasaco Vehicle Sketch Pad User manual

User Manual
Vehicle Sketch Pad
Version 1.7.92

VSP User Manual 2Version 1.7.92
About VSP
Vehicle Sketch Pad (VSP) is developed and provided free of charge by NASA Langley
Research Center.
VSP, and any related codes that might be obtained from NASA, are solely for internal
use at locations with an active Software User’s Agreement. Neither individuals nor
institutions shall disseminate any software or documentation in any fashion without
NASA’s expressed consent. Further, this software and support documentation are for use
only in the United States, by United States entities. Foreign nationals shall not be
allowed copy access to these materials.
Please visit our website for more information: http://vspmanual.webs.com
To obtain a software usage agreement for VSP, please contact:
Mark Moore
Aeronautics Systems Analysis Branch
Mail Stop 442
1 North Dryden St.
NASA-Langley Research Center
Hampton, VA 23681-0001
OpenVSP is a parametric aircraft geometry tool. OpenVSP allows the user to create a 3D model of an
aircraft defined by common engineering parameters. This model can be processed into formats suitable for
engineering analysis.
The predecessors to OpenVSP have been developed by JR Gloudemans and others for NASA since the
early 1990's. In January 2012, OpenVSP was released as an open source project available to everyone free
of charge.
www.openvsp.org
OpenVSP is available under the terms of the NASA Open Source Agreement (NOSA) version 1.3. The
complete terms of the license are specified in the LICENSE file which accompanies this program.
Copyright (c) 2012 United States Government as represented by the Administrator for The National
Aeronautics and Space Administration. All Rights Reserved.

VSP User Manual 3Version 1.7.92
Table of Contents
Chapter 1 Getting Started
Quick Start...................................................................................................................... 6
Things to Know............................................................................................................... 6
File Extension ............................................................................................................. 6
Figure 3: Navigating between folders......................................................................... 7
Main Screen................................................................................................................ 8
Geom Browser............................................................................................................ 8
Basics.............................................................................................................................. 9
Mouse Buttons............................................................................................................ 9
View Keys................................................................................................................... 9
Chapter 2 Intro to Modeling in VSP
Adding a Part ................................................................................................................ 10
Modifying a Part........................................................................................................... 11
All Parts ........................................................................................................................ 11
General Parameters (Gen) Tab.................................................................................. 11
Cross Section Formation (XForm) Tab .................................................................... 13
Chapter 3 Designing a Pod
Design tab ..................................................................................................................... 15
Chapter 4 Designing Wings
All Wings...................................................................................................................... 16
Planform (Plan) Tab.................................................................................................. 16
Foil Tab..................................................................................................................... 17
Multi-Section (MS) Wings ........................................................................................... 18
Section (Sect) Tab..................................................................................................... 18
Dihedral Angle of Planes (Dihed)............................................................................. 19
Hybrid Wing Bodies (HWB)........................................................................................ 21
Section (Sect) Tab..................................................................................................... 21
Fillet Tab................................................................................................................... 22
Exercises....................................................................................................................... 24
Ring Wing................................................................................................................. 24
Turning Pipe.............................................................................................................. 25
Chapter 5 Designing the Fuselage
Shape Tab...................................................................................................................... 27
Profile Tab .................................................................................................................... 28
Cross Section (XSec) Tab............................................................................................. 29
Chapter 6 Introduction to HAVOC
Definition...................................................................................................................... 31

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VSP User Manual 4Version 1.7.92
Chapter 7 Additional Parts
External Store (Ext_Store)............................................................................................ 32
Design....................................................................................................................... 32
Blank............................................................................................................................. 33
Definition.................................................................................................................. 33
Duct............................................................................................................................... 33
Definition.................................................................................................................. 33
Shape Tab.................................................................................................................. 33
Foil Tab..................................................................................................................... 34
Propeller (Prop)............................................................................................................. 35
Shape Tab.................................................................................................................. 35
Station Tab................................................................................................................ 36
Foil Tab..................................................................................................................... 37
Engine........................................................................................................................... 37
Definition.................................................................................................................. 37
Engine (Eng)/Nozzle (Noz)/ Duct Tab..................................................................... 37
Inlet tab ..................................................................................................................... 39
Chapter 8 Main Toolbar Features
File Menu...................................................................................................................... 41
Insert ......................................................................................................................... 41
Import........................................................................................................................ 41
Export........................................................................................................................ 41
Window Menu .............................................................................................................. 42
Window Split............................................................................................................ 42
Background Picture................................................................................................... 42
Lighting..................................................................................................................... 43
Labels........................................................................................................................ 44
View Menu.................................................................................................................... 44
Preset Views.............................................................................................................. 44
Adjust........................................................................................................................ 45
Alias/Antialias Lines................................................................................................. 45
Texture...................................................................................................................... 46
Geometry Tools (Geom) Menu..................................................................................... 47
Modify....................................................................................................................... 47
Component Geometry (CompGeom)........................................................................ 47
Mesh.......................................................................................................................... 48
CFD Mesh................................................................................................................. 48
AWAVE Slicing (Awave Slice) ............................................................................... 52
Mass Properties (Mass Prop).................................................................................... 54
Aero Reference (Aero Ref)....................................................................................... 55
Structural Modeling.................................................................................................. 56
Script............................................................................................................................. 62
Script Window.......................................................................................................... 62
Script Output............................................................................................................. 63
Vorview......................................................................................................................... 63

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Edit............................................................................................................................ 63
Input 1 Tab................................................................................................................ 63
Input 2 Tab................................................................................................................ 67
Slice Tab ................................................................................................................... 69
Control Tab............................................................................................................... 71
Execute Tab .............................................................................................................. 72
Revert............................................................................................................................ 74
Help............................................................................................................................... 74
About......................................................................................................................... 74
Chapter 9 Modeling Example
Wing.............................................................................................................................. 75
Tails............................................................................................................................... 75
Fuselage Layout............................................................................................................ 76
Editing Cross Sections.............................................................................................. 76
Prop............................................................................................................................... 77
Landing Gear ................................................................................................................ 78
Finishing touches.......................................................................................................... 78
Chapter 10 Tips and Troubleshooting
Tips ............................................................................................................................... 79
Glossary ......................................................................................................................... 80

VSP User Manual 6Version 1.7.92
Chapter 1 Getting Started
Quick Start
This section provides a basic understanding of Vehicle Sketch Pad (VSP), and is
intended to give a rudimentary understanding of how to use the program. Users are
advised to read the manual in its entirety to gain a more complete understanding of VSP.
Note: The Glossary (pg. 80) provided at the end of this document is
available to clarify any confusing terms.
Things to Know
File Extension
Vehicle Sketch Pad uses the .XML extension for its files. VSP can read .RAM files,
however the .XML extension should be used if files are to be edited.
Saving Files
Figure 1: Save options under the File Menu
When a new file is created, the Save As command should be used for the first
save. If a new file is saved with the Save command rather than the Save As command, it
will save as “VspAircraft.XML” in the directory of the vsp.exe program. After doing the
first save as, every successive Save will save the file under the name specified by the
user. Also, as with many other programs, users are highly encouraged to save their work
often.

Chapter 1: Getting Started
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Opening Files
Whenever you are prompted to open/import a file, a window similar to the one
shown below will appear.
Figure 2: Example of window to open a file
The type of file that is being displayed can be managed next to “Show” by using
the drop down menu. For this example, only .af file extensions will be shown. This will
help to condense the amount of information that appears in the main window.
In order to search for specific files, click on the periods placed before the
backslash, which is usually positioned at the top of the list. It is outlined in red below.
Click on specific folder names placed before the backslash to open a folder.
Figure 3: Navigating between folders

Chapter 1: Getting Started
VSP User Manual 8Version 1.7.92
Main Screen
Rotate model
Left mouse button
Translate model
Right mouse button
Zoom model
Center mouse button (or click scroll wheel)
(or left and right buttons together for two-button
mouse)
Center model in screen
“c” or View/Center Menu
User Select views
F1 to F4: Hold Shift and Function Key to set, press
Function Key to view again.
Preset Views
F5 to F12: Top, Front, Left Isometric, etc.
Geom Browser
Add a Part
Select the part from the drop down list at the top of the
Geom Browser Window, then click Add.
Delete a Part
Select Part from Part list, then click “Cut.”
Modify a Part
Select Part from Part List. The Part Window will
appear.
Wire View
Select Part from Part List or Select All, (“Sel All”)
then click “Wire.” (See Glossary)
Hidden View
Select Part from Part List or Select All, (“Sel All”)
then click “Hidden.” (See Glossary)
Shaded View
Select Part from Part List or Select All, (“Sel All”)
then click “Shade.” (See Glossary)
Show or No Show
Select Part from Part List, then click “Show” or “No
Show” (See Glossary)
Selecting All Children
Hold down “Alt” while choosing a parent and the
children of this parent will be selected.

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Basics
Mouse Buttons
The first and most important thing to learn about VSP is how to use the mouse.
Click and hold each mouse button to engage that button’s function, and release the button
to disengage the function. For example, the left button rotates the model around in the
Main Screen; as the left mouse button remains held and the user drags the mouse, the
model will continue to rotate in the Main Screen towards the direction that the mouse is
being dragged.
The middle button on the mouse controls zoom. Note that only moving the
mouse forward or backward will activate the zoom; when the zoom button(s) are pressed,
moving the mouse side to side will have no effect. For mice with a scroll wheel, click
and hold the scroll wheel to activate the middle button functions.
The right mouse button translates the model around the screen.
View Keys
The Function Keys at the top of the key board are for preset views. F1 through F4
are user-defined views. To set a user-defined view, adjust the model on the Main Screen,
then hold the Shift key and push the desired function key. To come back to that view
later, simply push that function key.
The preset views in VSP are as follows:
Key
Preset View
F5
Top
F6
Front
F7
Left
F8
Left Isometric
F9
Bottom
F10
Back
F11
Right
F12
Right Isometric
The “c” key has two functions: the first is to center the model in the Main Screen;
the second is to resize the view from the F5 through F12 keys. For instance, a fuselage is
added (and its default size is 30) for a small UAV. Pressing one of the function keys for
a preset view will give a view that is zoomed out too far to see any detail of the aircraft.
When the “c” key is pressed, VSP automatically zooms in to fill the Main Screen with the
model.
Note: The function keys (F1-F12) can only be used when the main screen
is selected or if the mouse is hovering over the main screen.

VSP User Manual 10 Version 1.7.92
Chapter 2 Intro to Modeling in VSP
Adding a Part
Let’s get into building a model. The first step is to add a part. At the top of the
Geom Browser Window, select the part type from the pull-down list. For the following
example, select POD. Then click the Add button to the left of the Parts window to insert
the part. Figure 1 below shows the Geom window and the list of available parts:
Figure 4: Geom window and list of available parts.
The selected part will appear in the Main Screen, and the Part Window will open.
The Part Window allows the designer to change all of the parameters of the given part.
Note: If the specific part is deselected by clicking anywhere else in the
Active window, the Part Window will disappear. To have the Part
Window appear again, just click on the part name in the Part List.
To remove a part, select the part from the list under the Active label and click Cut.

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VSP User Manual 11 Version 1.7.92
Modifying a Part
VSP allows designers to quickly and easily create nearly any aircraft imaginable.
In order to do that, parts must be modified to meet the design vision. The following is
organized by each part type.
Each Part Window has tabs to show different information on each part. Clicking
on the tab will bring up those parameters. The following descriptions start from the left
tab and work across to the right.
A word of warning: VSP does not deal with units of measure directly – in other
words, the program does not default to feet or meters, etc. All units for aspects such as
length, width, chord, etc. are given only as relative scalars. This feature allows designers
to quickly model aircraft without worrying about conversion errors – whatever
measurement system the designer normally “thinks” in can translate directly to the
design. However, care should be taken when modeling an aircraft using parts that have
been imported from other sources, as the designer of the imported part may have been
“thinking” in a different measurement system than the final vehicle designer!
All Parts
The first two tabs are the same for all of the available parts. The part POD is used
as an example in the following figures.
General Parameters (Gen) Tab
The General Parameters tab of the part window is shown below:
Figure 5: Parts Window for a Pod.

Chapter 2: Intro to Modeling in VSP
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Name, Material, & Color
Select a name and color that are easy to remember and helps to differentiate
similar parts. These are especially useful when building very complex models consisting
of many parts. The material for the part may also be selected, such as aluminum or glass.
Attach to Parent
There is a Parent-Child Relationship that can be added to attach separate parts to
each other. See the Glossary (pg. 80) for more details.
Fixed: The Fixed option allows XYZ attachment without the rotation component.
Mat (Matrix attachment): This allows the parent to control the rotation and movement of
its corresponding child (typical Parent-Child relationship).
UV: The UV option allows the parent shape to be modified and the position of the child
to change - for example, attaching a pod to wing using UV then changing the sweep of
the wing.
Note: The UV attachment is based off of the trailing edge of the parent
object. To use the UV attachment, select the child object, and in the
Transforms pane of the XForm tab, click Rel (Relative). Now in the Gen
tab, select the UV box. Note that V measures the child part’s attachment
from the trailing edge of the wing. Adjusting the U slider moves the
child part along the contours of the wing.
Note: V controls where the child is attached to the parent. This determines
the line followed by the child when it is translated in the U-direction along
the parent. For example, if V is set to 0 or 1, then the child will move
along the line that connects all of the points located on the trailing edge of
the parent. If V is set to some number in between 0 and 1, the child will
become attached to some point along the curvature of the local airfoil.
Thus, if V is set to 0.25, the child will be attached halfway between the
trailing and leading edges on the upper curve of the airfoil. If V is set to
0.75, the child will be attached halfway between the leading and trailing
edges on the lower curve of the airfoil. If V is set to 0.5, the child will be
attached to the leading edge of the airfoil. So basically, each airfoil is like
a closed circuit starting from V = 0 and ending at V=1.
Note: On a wing, if U is placed at zero, then the attached child will not
follow the shape of the foil.

Chapter 2: Intro to Modeling in VSP
VSP User Manual 13 Version 1.7.92
Tessellation
Users may add more cross sections and points to the edges of each cross-section
to make the model more accurate, but those with slow computers will not wish to add too
many, as this will begin to slow down the computer.
Export
This is a list of default names that may satisfactorily identify the part that is being
created. The name chosen is what the part will export as. Some other programs into
which parts may be imported may only look for these specific names when attempting to
import a part; thus, the nomenclature is important.
Cross Section Formation (XForm) Tab
This tab allows the designer to change various scaling and position aspects of the
part being modified.
Figure 6: XForm tab for a Pod.
Transforms
Absolute (Abs) or Relative (Rel) : Select whether the transformation should be in
reference to an absolute or relative coordinate system

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VSP User Manual 14 Version 1.7.92
Location (Loc): Change how the part is located and orientated in the X, Y, and Z
directions (X Loc, Y Loc, Z Loc).
Rotation (Rot): Rotate the part in the X,Y, and Z directions (X Rot, Y Rot, Z Rot)
Origin of Rotation (Rot Orig): This lets the user specify where the origin of rotation is
to be placed (0.0 being the leading edge and 1.0 being the trailing edge).
Symmetry: This allows users to modify the part quickly without having to do the same
work twice. Choose the symmetry about the plane on which the part is to be mirrored.
Scale Factor
Change the overall size of the object and then accept the new scale or reset it to the
previous scale.
Mass Properties
Density: Specify the density of the part.
Priority: Specify the priority of this part.
Shell Mass/Area: Specify the shell mass/area ratio.
Thin Shell: Click to specify a thin shell geometry.

VSP User Manual 15 Version 1.7.92
Chapter 3 Designing a Pod
Design tab
The design tab specifically for a pod is shown below:
Figure 7: Pod Design tab.
Length: Set the length of the pod
Fine Ratio: Set the fineness ratio for the pod.

VSP User Manual 16 Version 1.7.92
Chapter 4 Designing Wings
All Wings
There are three tabs that are common between all wing type browsers: Plan, Sect
and Foil. These three are explained below, and the ones unique to each type are explained
in separate sections.
Planform (Plan) Tab
The Plan tab is shown in the figure below:
Figure 8: Multi-section Wing Plan tab.

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VSP User Manual 17 Version 1.7.92
Total Planform
In this pane the user sets the planform of the wing as a whole.
Span, Projected Span, Chord, Area: These four parameters affect each other but can all
be changed to shape the entire wing.
Aspect Ratio: Cannot be set but is affected by a change in the span, projected span, or
chord.
Sweep Offset: Choose an angle from -85 to 85 degrees.
Foil Tab
The Foil tab is shown on the following page. The features on that tab are
described below.
Airfoil: Choose which section’s airfoil is to be modified.
Name: Although this field does not accept input data from the user, the displayed data
will change as the parameters below it are changed. For example, selecting NACA 4-
series from the drop-down box and changing the Camber, Camber Loc, and Thick sliders
will change the name of the NACA airfoil that is displayed in this field. This allows
designers to see which airfoil name corresponds to their selected parameters, or assists in
quickly setting the shape of the airfoil to be used if the name of the airfoil is already
known.
Invert Y: This button inverts the airfoil about the Y axis, and can be toggled on or off.
Type: Set the 2D airfoil shape. There is a drop-down list to choose the airfoil type.
Read File: There is an option to import an airfoil file with an “.af” extension. These files
define points that VSP will spline to make the curves of the airfoil.
Adjustments: Below the drop-down box and Read File button are parameters that may
be changed to modify the selected airfoil. Which parameters are active will depend on
the type of airfoil selected.
Note:At no time will all of the slider bars be active simultaneously.

Chapter 4: Designing Wings
VSP User Manual 18 Version 1.7.92
Figure 9: Multi-section Wing Foil tab.
Multi-Section (MS) Wings
Section (Sect) Tab
The section tab for an MS Wing is shown below.
Figure 10: Multi-section Wing Sect tab.

Chapter 4: Designing Wings
VSP User Manual 19 Version 1.7.92
Section ID: Choose a section with which to work. The section chosen will be highlighted
with a red box on the main screen. New sections may be added as needed: However,
note that new sections will be added to the right of the currently selected section.
Number Interpolated Cross Sections (Num Interpolated XSecs)
Section (Sect): Increasing the number increases the amount of sections in the part
selected. However, increasing the number of sections on slow computers will have a
detrimental effect on the performance of VSP.
All: Clicking on the arrows on either side of this field increases or decreases the number
of sections in every part of the wing.
Section Planform
Driver: From this list, the user may choose three out of the six parameters to define the
specific wing section.
The user must select which of the six slider bars become available. For instance,
selecting Span-TC-RC will allow the user to change the Span, Tip Chord (TC), and Root
Chord (RC) sliders (just below the Driver drop-down box), but will not allow them to
change the Aspect Ratio (AR), Taper Ratio (TR), and Area sliders.
Note: There is no way to have all six sliders active at the same time. This
is because VSP is parametric, and changing the characteristics of the
active set of drivers will by necessity change the inactive set in some
fashion.
Sweep and Twist: Choose any angle from -85 to 85 degrees for the specific section.
Also, the sweep or twist location can be chosen, 0 being the leading edge and 1 being the
trailing edge. This is the location at which the sweep angle is measured.
Dihedral Angle of Planes (Dihed)
The tab shown below in Figure 9 is only seen in a MS Wing part.
Joint ID
Choose which joint is to be modified

Chapter 4: Designing Wings
VSP User Manual 20 Version 1.7.92
Dihed 1: Adjusts the dihedral angle between the center and the joint of choice. (-360 to
360 degrees)
Dihed 2: Adjusts the angle between the selected joint and the next joint or the tip of the
wing. (-360 to 360 degrees)
Figure 11: Multi-section Wing Dihedral tab.
Blend Attach Points
Attach 1: Choose what percentage of the interior part that will attempt to blend with the
exterior side of the joint. (0.5 = 50%).
Attach 2: Choose what percentage of the exterior part that will attempt to blend with the
interior side of the joint. (0.5 = 50%).
Blend Tangent Strength
Tangent Strain (Tan Str) 1/2: Changes the strength of the blend which changes the
shape of the object.