I fly the P38L almost exclusively. When I started, I set the convergence all the way out. All the guns are in the nose, no need for convergence, right? Anyway, I read some posts about how the convergence setting affects the bullet drop over distance. So I went into offline practice, and used the .target function to see for myself.
Convergence doesn't actually affect "bullet drop" per se (if you define bullet drop as the effect of gravity and drag/air-density), but convergence DOES change how the guns are angled upward in order to converge at the pipper at your set convergence distance, which in turn does affect the ballistic arc. The reason this is important to understand is
your convergence does affect your vertical aim point to some extent (even with nose mounted guns) at different distances. You are correct that setting them at 300 will give you kind of a "middle ground", but you will still need to adjust your aim slightly, firing a little lower when in very close and a little higher when your target is further out.
I just tested this in the TA using a P38J and below are screen shots of my results. What is interesting to note is that when using the LONGEST convergence setting (650 yards) you get a very small vertical separation even when shooting well inside your convergence range (at 200 yards).
You can see when shooting a target at 200 yards with a 650 yard convergence (1st picture, left side), the vertical separation is not that great (only 1-2 feet above the aim point). On the other hand, when running a 200 yard convergence and firing at a target of 650 yards (2nd picture, left side), the vertical separation at distance is much greater (6-8 feet below the aim point), and in addition you start to see a 2-3 foot separation in the bullet patterns of the 20mm and 50cals.
Based on this information, if you're not sure
the distance you tend to shoot at (which should be a primary factor in choosing a convergence), then
for a beginner, I would actually recommend using the maximum convergence distance in the P38 of 650 yards, because this setting requires less vertical adjustment of the aiming point at various ranges and keeps the bullet streams of both the cannon and 50 cals closer together over a greater range. This advice applies ONLY to the P38, as longer convergence distances in other aircraft, especially those with wing-mounted guns, has other greater ramifications.
In the following screen shots, the distances of the targets is noted in the upper left. The pipper was always placed precisely on the horizontal line. The bullet patterns are 150 rounds of 20mm and 250 rounds of 50 cal fired in short bursts. Here you can see how the aim point will vary based on range and convergence setting:
Another valuable (but unrelated) thing to note is the relative size of the bullet dispersion patterns. At 650 yards the bullet dispersion is over 20 feet wide (even when running a 650 convergence), whereas at 200 yards the bullet dispersion is less than 10 feet. Point being, more bullets hit when you shoot in close -- one reason why it's always better to shoot at close range.
Hope this is helpful.
<S>
Ryno
