How to script particle systems?

Is it possible to somehow script or change a particle system? For instance, I would like to change the scale of the spawned particles, depending on the current speed of an actor. This could be used to create a cheaper smoke trail for a missile, by stretching the smoke particles in the direction of the rocket’s movement.

Alternatively, I could of course just always stretch them, independent from the speed, but in that case I would have to change the particles initial speed based on the rocket’s current speed.

You can use the Size By Speed module with GPU particles to achieve this.

Alternately, you can create a particleParameter for the sizeScale module, and modify the scale using a variable inside of a BluePrint to change the scale of your particles along an axis based on BluePrint logic.

For any of these solutions you will want to use velocity, rectangle alignment, or a mesh emitter.

Info on particleParameters