Well alpha blending manages transparency with alpha channel. Additive blending is simpler - it just adds the colour in a (properly configured) texture... but there's a hook, you need to set the black colour background colour and then flatten the image so that black is correctly interpreted as "transparency".
In some things in FS2_Open, additive blending works better than alpha blending... like in beam animations for example, and presumably on some other effects as well. It definitely looks to me like you're using alpha blending but I can't be sure, that's why I asked.
Also, I think I see some kind of darker semi-opaque edge around the bright part of the effect, which comes visible when two textures are stacked on top of each other in the game.
Considering the glass causing effects like this... well there would need to be uniformly vertical "grid" or array of thin lines, be they scratches, dirt or windscreen wiper marks or somesuch. The spikes are only seen perpendicular to this kind of conditions, which (sorry) I don't think are really plausible in fighter cockpits. If the effect could be made to adjust to cockpit texture or something like that, then it would be kick-ass, but all in all, static representations of energy/optical phenomena don't usually work that well as effects in a game.
