Thanks, J.T.O. - nice pic.
Perhaps I should make my language clearer: All the Sparrow launches I've seen, there is a clear delay from weapon release to motor ignition regardless of the station used for carriage. With AMRAAM, ignition and release seem co - incident, much as with the 'winder and other wingtip mounted AAMs.
Still no guarantee that my thinking's correct, though!
Regards,
Frank