View Full Version : Custom propeller basic tutorial

Zach Brockway
03-30-2012, 02:43 PM
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.

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.

03-31-2012, 12:49 AM
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 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.

04-06-2012, 09:00 PM
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?

04-06-2012, 09:04 PM
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.

04-06-2012, 09:08 PM
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.......

04-06-2012, 09:12 PM
This is what it looks like but with the white area surrounding would be transparent when using the tga. This is just a jpeg.

04-06-2012, 09:23 PM
This is what it looks like but with the white area surrounding would be transparent when using the tga. This is just a jpeg.

Is Just the one .tga used for both the CW and CCW versions?

04-06-2012, 09:24 PM
Yes sir.

04-06-2012, 09:30 PM
Yes sir.

Sweet............. I just can't believe that I will be able to use counter-rotating props .

WOW............... By the way thanks for your time and expertise..

04-06-2012, 09:32 PM
It is definitely a good move forward. :) Your welcome.

04-08-2012, 06:51 PM
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.

04-08-2012, 09:04 PM
Sweet............. I just can't believe that I will be able to use counter-rotating props .

I know that Doug Kaye's (dhk79) Bugatti racer had contra-rotating props. Version G3.5 :)

10-14-2012, 05:47 PM
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?

10-14-2012, 06:33 PM
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.

04-20-2013, 09:04 PM
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.

04-20-2013, 09:44 PM
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.

04-21-2013, 02:35 PM
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.

04-21-2013, 03:25 PM
I mean in photoshop or GIMP. It's just a blur filter.

08-20-2013, 04:31 PM
I finished the video tutorials for creating custom propellers for RealFlight. They are of the Youtube variety. I have attached the source files for the project. Remove the rfx extension to use.
Modeling a prop. (http://www.youtube.com/watch?v=zgT7fLk7cYg&feature=youtu.be)
Mapping the prop (http://www.youtube.com/watch?v=fnKidvJh8uI&feature=youtu.be)
Creating prop textures (http://www.youtube.com/watch?v=kKMNj8QRJGw&feature=youtu.be)
Finishing and importing Kex files. (http://www.youtube.com/watch?v=0rv99OAmhvM&feature=youtu.be)

08-20-2013, 05:00 PM
Thanks Boof!!

08-20-2013, 05:14 PM

08-23-2013, 02:08 PM
Excellent videos Boof.

I may have missed it being mentioned, but how are individual blades given a unique CS? For example, a scale prop may have the manufacturer logo on only one blade.


08-23-2013, 10:10 PM
That is unfortunately not possible. You make a single blade and set how many blades the prop will have in RF.

05-23-2015, 11:01 AM
I am interested in making a variable pitch propeller for a model(s) but I can not find the specifics on how to make the variable pitch. I have searched and I can not find anything other than this thread. Am I missing something or did it not get posted.


05-23-2015, 01:08 PM
Couldn't find anything as well when I was looking. Waiting for captain.

05-23-2015, 08:36 PM
You could probably make the Prop V-Pitch once you import the prop into Realflight. Once you have it in the sim, you will have to edit the .propeller file. change the No to a Yes in the correct location. You find this in a similar place where the RFVehicles are found in your documents folder.

05-24-2015, 05:45 AM
I think it's more about the animation. Making a VPitch one without pitch animation is easy, you can just import any custom prop this way.

05-24-2015, 08:03 AM
Just a shot in the dark here, but you'd probably have to create it the same way you would a heli blade. Just a thought since I've never done a blade befor .

05-24-2015, 05:16 PM
Any custom propeller can be made into a variable pitch but the animation is the nut to crack. A few things need to be done. Import your custom propeller then simply use the v-pitch prop that comes with RF to use as the "Based Upon" (See attached picture). This will give you the correct options in the "Engine" settings to get Variable pitch. You will want to make a new output channel and servo to control the pitch. You will also want to change the throttle channel as well. It will need a complex input to allow the use of the graph to make a throttle curve. The curve should be 100, 0, 100 at low mid and high positions respectively. The new output channel for pitch can be a simple feed set to the throttle channel. Now when you select your new prop you will see settings for Minimum and maximum pitch °. Also you can pick the new pitch servo you just made under "Variable pitch servo". Now your model will behave as if it has variable pitch but the animation doesn't work. You really never see that anyways. I can describe the method for putting this behavior on a switch too. That way you can have variable pitch "Mode". I've attached this RFX of my stamp mono. I imported a custom propeller and used the v-pitch prop as the physics setup. The dual rates switch in the "UP" position gives v-pitch mode and in the "DOWN" position it's normal. Just check out the output channels "3" & "8" in the "Radio" tab. Pay attention to the "Input" and the "Input Feed When" sections. Also look at the "Pitch" servo under the "Electronics" tab. Finally look at the "Engine" section under the "Physics" tab. That's where all the V-Pitch settings will be.

05-24-2015, 07:57 PM
Sorry for any confusion that my pervious most may have caused. What I was trying to say was, how to animate it the kex in Realflight. not how to set up the .rfvehicle or .propeller files. I was wondering if there was supposed to be a magic name in the hierarchy like ~CS_PIVOT or something to go between ~CS_HUB and _BLADE that rotates the blade with the physics. So it acts/looks like the V-Pitch and not like the Griffin Combat VTOL.

05-25-2015, 02:17 PM
Upon further investigation there is a dummy object included with the V-Pitch propeller. The name KE used for the V-Pitch dummy object is ~CS_PivotBlade It looks like RF creates a second blade and names it the same as you name it with "_1" added to the end. The ~CS_PivotBlade is also copied and given the new suffix. I would assume that you should use a point helper at the root of the blade with the X axis pointing down the blade. The PivotBlade should be a child of the Blade. The attached picture shows the source for my information. No guarantees that this will make the animation work.

05-25-2015, 05:01 PM
I have determined that the ~CS_BLADE is the "dummy" blade that real flight looks for to replicate and the ~CS_BladePivot should be the child of ~CS_BLADE and should the visible propeller blade and will pivot along the x-axis for the CW blades and the negative x-axis for the CCW blade aka rotate the pivot around y 180 degrees

05-25-2015, 05:49 PM
The ~CS_BLADE is the visible geometry as shown in this threads original post. The ~CS_PivotBlade is the "Dummy" object.

05-25-2015, 07:27 PM
The ~CS_BLADE is the visible geometry as shown in this threads original post. The ~CS_PivotBlade is the "Dummy" object.

Yes I under stand that. But the only part of the Hierarchy that rotates with the variable pitch is ~CS_BladePivot. ~CS_BLADE is stationary and cannot rotate. The ~CS_BLADE object tells real flight that it and all of its children are part of the propeller blade and should be duplicated, ~CS_COLL ~CS_GLOW... Or in the way that I found that works for V-Pitch props is to name some object cube etc. ~CS_BLADE. Then name the visual blade ~CS_BladePivot.

I tried HUB->"visual blade" (~CS_BLADE)->"dummy object" (~CS_BladePivot). Both the ~CS_BLADE and ~CS_BladePivot were duplicated and rotated around the y-axis. However, ~CS_BLADE does not rotate with the variable pitch and the ~CS_BladePivot pivot rotated with the v-pitch

I also tried HUB->"dummy object" (~CS_BLADE)->"visual blade" (~CS_BladePivot). And it worked/looked as a variable pitch propeller should.

I am not saying I am perfectly right. I am just reporting what worked for me.

05-26-2015, 01:20 PM
Well I'm glad you figured it out.