True Altitude?

[Soldier_Fortune]

Originally Posted by FrankB

...until I switched from SB-2 to Ju-88 or B-25.
On both maps and both altitudes the bombs fell always short. Too short. Maybe 2-3 bombsight degrees.

This has nothing to do with the equations, but with the plane's attitude.

Both, B-25 and Ju-88, tend to sink more than other bombers. Therefore, when you engage the Level Stabilizer, automatically the plane will increase the Angle of Attack (AoA) trying too keep the altitude while damps the sinking.
This action avoids the bomber flies leveled, even if the level indicator and the variometer indicate that, and thus the bombisght is aiming to certain forward angle by default. You should substract this angle to that you've computed for a manual drop.

I've found that forward angle is about +3º when the Level Stabilizer is engaged and it is combined with fully trimmed elevator. For other elevator trimming, this angle would be a bit less... but I've not found an "universal" linear ratio for this matter. Too many variables are involved: TAS, altitude, payload, wind...
Therefore it's all about how well the player knows his plane's behavior at different speeds and altitudes under different external cirumstances, how well skilled he is to fly it using the proper trimming, and his jugdement about what is the actual AoA.