Your problem is in the DP file. If it does not have a number for the quantity of Bombs in the DP the bombs will vanish when dropped.
Here are the entries for the Wildcat.
The entry [guns.2] is the bombs entry. The first entry after gun.0= is the number of bombs.
The easy way to fix it is to use DPED a windows based prog. to open and modify DP files.
Remember to delete the CDP file after making changes. CFS2 will rebuild it at next startup.
Hope this helps,