I've seen the same picture, but it was described as an early radar mod for the BAT self guided weapon. Later mods used a more conventional radome, like this other picture. The BAT is the white object under the wing. These were operational in the Pacific theatre in 1945.View attachment 1170972
This is a side photo of a PB4Y-1 fitted with rocket rails to evaluate air-launch rockets. 1944
Those were scientifically advanced for the day. The ring mimic's the magnetic signature of a ship passing overhead, tricking the mine to detonate. To save weight, there were no guns or bomb racks. The magnetic field that was generated meant that a conventional magnetic compass wouldn't work, so a gyrocompass was installed. Powering the magnetic field required a 35 Kw generator which was driven by a Ford flathead V8.Vickers Wellington magnetic mine sweeper.View attachment 1171266