i fly the H111 and Ju88 most time in the game, mainly on ATAG server... u dont need calculate so much IAS <-> TAS...TAS<-> MPH... the target cross do not shows the impact point of the first bomb, it shows the impact of nearly the last bomb of a intervall drop, imo
i drop 8 *250kg Intervall of 8 , distance 40m......
since i use it in that way, correct height and IAS, i have a high hit qoute in the H111,
seems to be reserved, like a few things in the game

maybe it would be explain, why the bombs explodes backwards, aswell...
but i still prefer the mighty Ju88 and dive bomb, h111 i use for afk flights :p