Custom propeller basic tutorial

Zach Brockway

New member
On the heels of support for custom helicopter visual blades comes support for custom propellers! Again, this post is intended to be a brief introduction to the authoring requirements, and a more detailed tutorial will be posted at a later date.

Note that it’s possible to create both variable pitch propellers and folding propellers; however, the specifics are not covered in this initial post. We'll let you know when the full tutorial is available.

Overview
A RealFlight propeller is comprised of several distinct components: a clockwise blade model, a counterclockwise blade model, a blur disk model, and a side view texture. You are not required to provide a blur disk model for a propeller; if the blur disk is omitted, RealFlight will use a default blur disk. Texturing for blur disks is a special case and will be described in more detail later.

The KEX Import Wizard process will prompt you for any one of the three KEX models, then it will automatically locate the other two based on their filenames. You must therefore follow the naming conventions described below for the import to succeed.

The wizard will then prompt for a name and a basis for your propeller. RealFlight's import process will automatically create new KEX and texture files using the name you provide. It is also the name by which the new propeller will be known in the sim.

Once you've imported a custom propeller, you can then select it from the Vehicle Editor for your custom EAs and variants, and it will be included with them when they are exported as RFX files to share with other users.

The orientation of the frames’ pivots, as well as the orientation of the frames themselves in world space, MUST match RealFlight's expectations in order to work properly. Pay close attention to the attached screenshots and the XYZ axes shown.

Single Blade Geometry
(e.g. MyProp_CW.kex, MyProp_CCW.kex)
Both a clockwise and counterclockwise KEX are required. Their filenames must end in _CW and _CCW, respectively, as shown in the example above.

The clockwise and counterclockwise propeller blade models each require a single frame called “~CS_BLADE", which should also be the parent of a collision frame ("~CS_COLL"). It is important to scale the blade so that it has a radius of exactly 1 foot (measured from the origin) in 3ds Max. The ~CS_BLADE frame is rotated and duplicated according to the number of blades that the vehicle’s Engine Component is configured to have.

In addition to the ~CS_BLADE frame, you can create a frame named “HUB” which will contain geometry that is NOT duplicated according to the number of blades.

The pivot of both frames should be positioned at the propeller’s axis of rotation. The frames should in turn be positioned so the pivots are at the origin.

Refer to the screenshots attached to this post for the correct orientation.

Blur Disk Geometry (optional)
(e.g. MyProp PropDisk.kex)
If a blur disk is provided, its filename must end in " PropDisk" (note the space), as shown in the example above.

The blur disk requires a single frame called "~CS_BLADEDISK" and does not require any collision geometry. The blur disk pivot should be positioned at the center of the disk. The object should in turn be positioned so the pivot is at the origin.

Refer to the screenshots attached to this post for the correct orientation.

Side View Texture
(e.g. MyProp Side.tga)
This texture is designed to provide a view of the propeller in motion when viewed edge-on. It should include motion blur, and should be carefully matched to the profile of the blur disk shape.

Single Blade Texturing
The clockwise and counterclockwise single blade models are textured as you would texture any other model. They do not support normal or specular maps at this time. Most often, it will make sense for the clockwise and counterclockwise models to share a common texture, although this is not strictly required.

Blur Disk Texturing
The texturing of a blur disk model is handled specially; the UV coordinates specified in the model are disregarded by RealFlight, and new UVs are automatically generated.

The UVs generated will map to a single horizontal row of pixels approximately 15% of the way down the texture. The left side of the row will map to the inside edge of the disk, and the right side will map to the outer edge. In many cases this is effective enough that a special blur disk and texture are not required.
 

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Boof69

Well-known member
Just for a clarification of what's described here. If you are making a custom propeller you will need no less than 3 files.
  • MyProp_CW.kex
  • MyProp_CCW.kex
  • MyProp Side.tga

As stated above the .kex files require an _CW or _CCW while the Side.tga requires a space in the same place.

The Side.tga is unique in that it has no particular uni-dimensional size and that it is not applied to anything object in 3ds Max. Also to get it to render properly it will need an alpha channel masking the background with black and saved as a 32 bit image.
The way I generated a Side.tga was to first map and texture the propeller. Once done I rendered the single blade in the orthographic TOP view at 1024x768 resolution. This gave me a good Side view. I opened the render in PS And oriented it vertically. Then applied a 90° motion blur. Then using the selection acquired from the side view layer thumbnail I switched to the channels pallet and added an alpha channel then filled the selection white. Then I cropped the image and saved as a 32 bit .tga. All this was after a few tries having alignment and alpha problems.

Another point that wasn't immediately clear was that not only are _n and _s maps not supported, but any amount of specular level or glossiness applied as a baked material will not be tolerated in the sim. My prop came out as a chrome blade.

It's hard to notice in Zach's pictures above that The pivot must be set to the rear of the prop hub as well as at the prop blades center of rotation. Once there then center it to the origin 0,0,0.

I attempted the optional blur disk but couldn't figure out what tga to apply to it since one is required.

I hope this helps until the full tutorial is posted.
 

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Deewng

New member
Boof69 Hello

From your clarification, is the side view .tga from the edge view of the prop disc in the shape of the blade's profile radius?
 

Boof69

Well-known member
No it's just taken from a render of the prop blade itself. I couldn't get the propdisk figured out from the basic tutorial. So my prop is using a default propdisk.
 

Deewng

New member
No it's just taken from a render of the prop blade itself. I couldn't get the propdisk figured out from the basic tutorial. So my prop is using a default propdisk.
OK soit is a basic map of the single blade + hub. And they are going to now support counter rotating props? CW aand CCW of the props to be used?

Quite a step forward.......
 

jeffpn

Well-known member
Zach, could we get a sample propeller including a blur disc, with all required files, including .tga files?? I don't know how to determine where "approximately 15% down" would be. I'm not following that.
 

abaser

Well-known member
Zach, could we get a sample propeller including a blur disc, with all required files, including .tga files?? I don't know how to determine where "approximately 15% down" would be. I'm not following that.
Did we ever get this sample blade?
 

Boof69

Well-known member
Nope. The blur disc is easy to make. Use the tutorial I made for the heli blur disc.
I think if you map the blade and orient it horizontally with the hub on the left on the map the sim will apply a row of pixels 15% of the way down the tga to the blur disc and spin it.
 

willsonman

Well-known member
So, I went to go make my first custom prop. It looks great sitting still but when it moves I think I may need to create a blur disc and somehow get the alignment right on the side profile. Not sure how to do that one. I'll review the blur disc tutorial but can anyone elaborate on how the side.tga should be properly generated? Hopefully the pictures attached will better describe what I am saying.
 

Attachments

Boof69

Well-known member
What I did was to build the prop map it then apply the final texture. Render the prop in orthographic view. Take the render into PS rotate it so it's vertical and apply a vertical motion blur. Select the background and apply black in the alpha layer. Now crop the whole thing so the middle of the hub is at the bottom of the image and it is fairly close all around the blade. Name it correctly and save it in the same folder as the CW and CCW kex files. The default blur disc does the job just fine for conventional props. If you want the blur disc to look right you will want your blade tga to have the blade texture oriented horizontally so the middle of it is 15% down from the top. Take the tga veritical size and multiply by .15 and use the rulers in Photoshop set to pixels to find the right spot. For example for a 2048x2048 you will want to move the blade texture to 307 pixels down from the top. The pixel row at 307 pixels will be rotated to texture the blur disc.
 
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willsonman

Well-known member
Vertical motion blur? I've never been good at rendering. Lighting used? Ortho view in max in another foreign subject. I guess I bit off too much again.
 
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