I was recently working on creating a bomb trajectory indicator using labels, and I didn't want to have to calculate the drag force on the bombs for it, so I set the bomb's drag scale to zero. I put it all together and tried it, only to find that the bombs would fall short of the indicator each time I dropped them.

I thought the bombs somehow still had drag, so I tested this by dropping two Boom 50s side by side, one with a drag scale of zero and one with a drag scale of 100. The Boom 50 with drag had "calculateDrag" set to "true", and they both had massScale=1. Dropping both bombs at the same time, I found that their trajectories and points of impact were identical, despite the extra drag on the one Boom 50.

Using this, I have concluded that, at least for the Boom 50, there is effectively zero drag, even when the dragScale is manually increased. So if you wanted to build any bomb aiming tools, but didn't want to do the differential calculus, there's no need to worry! The bombs are practically drag-less.