Creating a model for CRRCSIM

Creating a simple model for CRRCSIM

Introduction

The standard CRRCSIM distribution contains several models. Many of these are not very highly detailed as those in other RC flight simulators. Detailed models can be created, however, and creating a simple model and adding detail is possibility.

The process for creating a basic model for CRRCSIM is easy if you are familiar with using Wings 3D. Simply create the model and export the 3D object to the .3ds file format. The configuration file has to be edited to model accurate flight characteristics.

All this will be covered in this tutorial.

Overview

The process of creating a new model takes two steps: the first step is to create the 3d model using Wings 3D. (Or Blender, but Wings 3D is easier to learn ). The second step is to copy an existing model flight model configuration file and make changes where necessary: for example change the wingspan and center of gravity, weight of model and so on. This will make sure the model flies much like the actual R/C model.

Front and side view of the PC-9 model created in this tutorial

Step 1: Creating the 3d Model

(a) Creating the Fuselage

Open Wings 3D and right click on the desktop. Choose Cylinder. Rotate it around the x-axis. Select the entire object and scale it in the X direction to make it slimmer. Next select the front face and extrude the front in the Z direction. Scale the front section to make it narrower. Do this with the rear fuselage.The diagram of the basic model (Figure 1) should help.

1 unit will convert to 1 ft in the simulator. If the model wingspan is 3 ft wide then make sure it is 3 squares wide as shown in Wings 3D

(b) Creating the Canopy

To create a canopy, create a sphere and then rotate it about the x- axis 90 degrees. Move it down into the fuselage. Add transparency to the material you use for the canopy.

(c) The wings

The wings are just flattened cylinders, with the edges scaled for taper in both directions, the same goes for the tail plane. The vertical stabilizer is made in two parts, which allows for the fairing at the bottom

(d) Wheels

Add the wheels as small flattened cylinders. The landing legs can be very simple since this is a model and a non-retractable model at that.

(e) Colors

The last part is adding colors using materials. Create a black transparent material for the canopy and red for the fuselage. You can select other parts of the surface and color them as needed.

(d) Export to CRRCSIM

Export the model to 3 D Studio from the Wings > Export Menu into the CRRCSIM OBJECTS folder, naming it Pc9.3ds

Building the model in Wings3D

Figure 1: Creating the model of the PC 9 using Wings 3D. Basic knowledge of creating cylinders, spheres, extruding, scaling and adding materials (coloring) should be enough at this point. The model can be compared to pictures and refined later.

Step 2: Modifying the XML file.

First make a copy of the sport.xml file and rename it as your model, for example, PC9.xml

Open the file and add comments to the file as in the example below:

<?xml version="1.0" encoding="iso-8859-1" ?>

<CRRCSim_airplane version="2">

<name>

<en>crcpc9v8</en>

</name>

<category>TurboProp Trainer</category>

</categories>

<en>This plane has been automatically converted from sport.air. Please update this text if you know more about it. Further modified </en>

</description>

<date>Unknown</date>

<author>CRRCSim 0.9.5</author>

<en>Automatically converted from .air file.</en>

</change>

<author>Jan Reucker</author>

<en>Added steerable nosewheel.

</en>

</change>

<author>Your name goes here as author of the change</author>

<en>Changed descriptions and a few other parameters for the airplane

</en>

</change>

</changelog>

The model selected in this case is a PC-9 aircraft with the following dimensions. the model is built to 1:10 scale. Some values therefore have to be calculated and changed in the model. The other parameters are left unchanged, however these can be adjusted after test flying the model.

Actual

Span (span) ft

Area (area) sq ft

Calculated Chord

(ref chord) ft (Calculated by dividing area by span)

Real Aircraft

33.2

175.5

11

175.5/33.2 = 5.28

Calculation

33.2/10

175.5/100

5.28/10

The weight is taken as 20 oz which about the standard for a commercially built electric foam model with all equipment installed

(See any R/C model specs). Mass must be in the unit of slugs, therefore divide by 500. Mass = 20 oz / 500 = 0.03 slugs

The items you need to change are highlighted in red below. (units ="0" means imperial units, feet, pounds..)

<lift CL_0="0.108991" CL_max="1.1" CL_min="-0.6" CL_a="4.81276" CL_q="7.24396"

CL_de="0.24722" CL_drop="0" CL_CD0="0" />

<drag CD_prof="0.067" Uexp_CD="-0.5" CD_stall="0.15" CD_CLsq="0.01" CD_AIsq="0"

CD_ELsq="0" />

<Y CY_b="-0.81642" CY_p="0.00979" CY_r="0.333907" CY_dr="0.22749"

CY_da="-0.02761" />

<l Cl_b="-0.0240925" Cl_p="-0.462504" Cl_r="0.0460948" Cl_dr="0.0188651"

Cl_da="0.143837" />

<n Cn_b="0.148155" Cn_p="-0.0138288" Cn_r="-0.157387" Cn_dr="-0.111666"

Cn_da="0.0117119" />

</aero>

<descr_long>

<en>Automatically converted from sport.air.</en>

</descr_long>

<descr_short>

<en>default</en>

</descr_short>

<mass_inertia version="1" units="0" Mass="0.031" I_xx="0.0456257"

I_yy="0.0882453" I_zz="0.0882453" I_xz="0.00304607" />

</sound>

You must change the name of the 3d model file as follows: . <graphics version="1" model="pc9v8.3ds">

Just load CRRCSIM., select the model and start flying.

For more detailed descriptions of file parameters see here. For further details, refer to the documentation in the Links section.

Adding Textures to a Wings 3D model

Textures can be added in Wings 3D. Shown below is a test object, a cube, with the default textures added and imported into CRRCSIM.

Cube textured in Wings 3D and flown in CRRCSIM

Updated 7 June 2016:

Updated 11 May 2021: