I will start this with a design I have been working on for my B-25. this drop will drop 8 or 10 bombs in sequence. this is just basic and seems to work good in theory but I will take any advice on modifications.

The green section on the pic below is a pice of 3/32 lite ply. The yellow sections are 1/8th inch brass tube with a slightly larger than 1/4 inch gap in between. the thin red lines running through the brass is 1/8th inch music wire that is attached to a 1/8 x 1/4 inch piece of spruce (black bar). attached to the black bar is a linkage that a music wire is connected to and runs to a bellcrank then up to another one and over to a servo.

The wires are just slightly longer than the next one so as the bar is pulled the first bomb will drop then the next then the next and look more scale rather than all at once. Now the bomb will have a 1/8th inch x 1/4 brass tube mounted to its back like a model rocket lug and will fit into the gap between the tubes on the rack.

Now remember on bombers they have 2 racks facing each other so you will have to calculate wire length so that the right bomb then left bomb then next right next left etc drops in that order. this is still planning and next is to build a mockup and try it but I hope this gives some ideas and feedback.

as a note you can also adjust the length of tubes on the bomb for adjusting the drop sequence.