Check our website
http://www.warbirdsofprey.org/index.php?board=4.0Check the UP/4.10/4.11 manuals for some other information as well, especially as to torpedo use and bomb arming. The 4.10 manual, for example, starts discussion of these at p. 25.
Check Mission4Today for some bombing guides
http://www.mission4today.com/index.php?name=Knowledge_Base&cat=38. The guides are generally for stock, but apply for the most part with mods.
Also download the Bombsight Table 2
http://www.mission4today.com/index.php?name=Knowledge_Base&op=show&kid=337, which is a great tool to help you with your bombsight angles for level bombing.
Check
http://www.simhq.com/_air10/air_307a.html and
http://www.simhq.com/_air10/air_311a.html for ground attack and skip bombing tutorials.
The older sources don't address the bomb arming issues. They are still useful, but it really means you just need to drop your bombs earlier and from a slightly higher altitude when doing ground attacks. In the old days, I would drop a bomb about 10 ft. above the target. Now, you need to drop from 100-200 ft. minimum. My guess is that you are dropping too late.
Get on TS and ask for some help when there are some bomber pilots around. Most bomber pilots would love to have another bomber in tow (as a target for fighters, at least

), and won't have a problem teaching you some of the tips and tricks.