The doppler effect being a pitch shift perceived when the source is moving (going down as the source goes away), did you try with a pitch shifter and automation ?
The doppler effect being a pitch shift perceived when the source is moving (going down as the source goes away), did you try with a pitch shifter and automation ?
That'd be what I'd try. Automate the pan to move from one side to the other, probably using a logarithmic curve as opposed to a linear one (logarithmic is the one that starts off steep and gets shallower as it goes). Then automate the pitch down a few semitones during the steepest part of the pan.