I discovered that the original threshold distance for triggering the commencement of flak is the line of sight distance, NOT the separation as measured along the ground. The original threshold was set at 10km. This means that if a plane is more than 10,000m higher that the flak barrage object (when placed on the map is located on the ground) no bursts will be created, even if the plane is directly overhead.
I've altered the code so as to use the ground distance, meaning that no matter the plane's altitude the flak will commence at the same ground distance from the flak barrage object. Actually, I think I'll make this variable with height, such that the triggering distance increases with plane altitude.
I've been experimenting with dynamic variability, based on the plane height, for:
- The areal coverage, increasing with altitude.
- The dispersion in height, increasing with altitude.
- The rate (and hence number) of bursts, increasing with altitude.
In the 2-panel image above, the views are captured at the same distance from my B-17. In the top frame the altitude is 24,000' or 7,300m. I have the code structured so that from ground level up to 10,000m:
- The box area increases from 1km x 1km to 4km x 4km.
- The 1-sigma dispersion in depth increases from 75m to 188m.
- The rate of bursts increases by a factor of about 4 (to partially compensate for the much larger volume).
The two images above show the differences in these three parameters over a large range in plane altitude.
I have more testing to do, especially to see what happens when there are two or more flights passing within the triggering distance, and when they are at different altitudes.