For those that are interested... I took the time to put together some screen-shots of the effect different convergence settings have on trajectory. Particularly with wing-mounted guns, having the convergence set too close can cause some pretty serious misses, and can have almost the opposite effect some people would expect.
The last few posts of this thread-
http://bbs.hitechcreations.com/smf/index.php/topic,291146.0.htmlAs far as cannon rounds and MG rounds hitting the same place at different times... I think a lot of that has been "over-thunk". In a case where the target has no apparent motion (dead-six or HO) the small time difference doesn't matter, and it would probably be best if all of your rounds hit the target, rather than having some hit high or low (although the difference in actual trajectory may not be enough to matter, either, I'd have to check).
In cases where the target has apparent motion (crossing shots or shots where you're pulling lead) it's just plain impossible for a cannon round and a machine gun round
fired at the same time to hit the same target, because the lead required is based on
timing, much more than on trajectory. The cannon round will require more lead, because the round takes longer to get there, allowing the target to move further to the side. In order to pull the required lead for the cannons, the mg rounds will pass in front of the target.
Setting cannon rounds out an additional 50-75 yards effects their vertical trajectory by inches, or a foot or two at most. That's not enough to allow for the difference in timing.... If the target is moving to the side at an apparent 120mph, and the cannon round takes 1/2 second longer than the mg round to arrive, the cannon round will pass roughly 90 feet behind the target (assuming the mg round has the correct lead to achieve hits).
It gets worse if the difference in time between impact gets longer, or the apparent side/side speed of the target increases.
There's nothing you can do with convergence settings to allow for that.
If there was... You'd still have to fire while your wings are level and at 1G to make it work.
As soon as you tilt your wings to the side, the apparent gravity changes, and instead of the rounds being pulled "down" (which is compensated for with the vertical tilt of the mounted guns) they're pulled to the side and down, or just to the side (if you're knife-edged), or even up and to the side or straight up (if you fire while inverted)... All the effects of which are (A) not compensated for at all, or (B) made worse by the fact that the guns are mounted with an upward tilt to compensate for gravity in wings-level firing.
Think about it for a minute... What happens to the trajectory curve when you roll the plane on it's back and fire? It reverses, which has the effect of making all of your rounds appear to hit extremely high from your upside-down perspective.
When you fire while tilted to the side (to the left in this example), the guns no longer have enough vertical tilt to compensate for gravity, so the rounds hit low. Plus, the guns which started out with an upward cant, not have a left cant instead, which makes them go left. So now they're firing left and low, but we're not done. The guns are also canted inward to meet at convergence. That means that in a left bank, the guns in the right wing are tilted downward, adding to the apparent effect of gravity, making them go even lower. But the guns in the left wing are canted upward to some extent now, making the rounds fly "flatter" than the rounds from the right wing. We're not done yet. Add in the fact that if you're firing while banked, most people are firing while pulling more than 1G... Eeeks!
And extending the convergence for the cannons by 50-75 yards is supposed to overcome all of that?
Of course, there's still more at play here.
Sometimes we fire while climbing or diving... That makes the trajectory of the rounds flatten out. The greatest trajectory is seen in a horizontal shot, the least is seen in a vertical shot. Rounds that are launched straight up or down won't have any trajectory curve at all (until the upward-fired round stops and falls back). This means that if you fire directly at the guy roping you, while you're vertical, you'd better aim "low" or you'll miss him! Imagine the trajectory curve of a bullet fired while you're vertical. The round will pass through the LoS earlier than "normal", and will never come back "down" through it.
And, toss in the effects that different speeds and altitudes play...
We can't compensate for all of those factors (if any??) with convergence settings. We compensate for it by firing a
stream of bullets/cannon rounds, and allow our target to fly through it. Or get the lead right for either your MG's or cannons, and do the best you can. And we compensate for it by doing the best we can to fire while at 1G, and with wings as level as possible, or at least to mentally compensate for the inability of our mechanical devices to compensate for the situation we're currently in...
