I am trying to add a sort of engine glow to a model. I have found a solution that looks good enough for me in the 3D viewport preview, but looks very different in the final render. Here is an image of the effect:
You can see how the transparency of the 'flame' is vastly different in front of the transparent background. This is especially confusing because this is not the case in the 3D viewport.
Any ideas what I am doing wrong here?
If it helps the blender file can be found here: Blend File