"Scissoring" Convergance?

[Lusche]

Nice graphs Lusche,I think you may have a mistake on the first 1 tho.

 You show the inner guns in green and I think at the 600 yard range you placed them in the wrong order!

 small mistake and I may be wrong but wouldnt the order be black red then green like you have in the 2nd graph or atleast have a reversed order?

I just checked, and no, I did not. The black pair is always the outermost, even past the convergence point. It only that the left & right "black guns" are swapping their position with each other

Quick sketch:

[Lusche]

Also wouldnt the guns be the same distance as they are apart at 800 yds if they converged at 400,from the looks of the graph you have them same distance apart at 600 yds.

The first range group shown is 200, not 0. Thus it's looking like the 600 yards group, both have the same distance from the convergence point at D400.

Anyways the graph planely shows that a staggered convergence never acheives the bullet density that a single convergence point does.

Actually I wasn't really aware of that until this thread came up and I started to do these graphs. I love learning things that way

[dtango]

Thought I would add a few thoughts to the thread.  WW2 aircraft crews used both converged or staggered "box pattern" settings demonstrating it's not quite as cut and dry.  Qualitatively single point convergence will give you more concentration of fire while a staggered setting will cover more area.  Here is a snippet from a gun harmonization chart for the P-51B:





Yes, I used 6 guns vs. 4 (I did this a long time ago for the 412th to think about the P-51D) but the graphic is enough to demonstrate the point.  As can be seen single point convergence is concentrated fire (~ 3 ft^2) where spread convergence covers more area.  Of course just how much difference does the spread make vs. not?  It's hard to see on this diagram though you can see the spread marked off at 5ft increments from the centerline to try and gauge it.  I don't have time to blow the picture up so we'll just use a pic from Andy Bush at SimHQ to zoom in a bit:



This is a gun chart showing convergence for guns at 250 and 350 yards.  Notice if the guns are staggered as such there's a diamond hence the "box pattern" between 250 and 350 yards.  Using this staggered convergence the bullets are anywhere between 0ft to ~4ft from the centerline (0ft ~8ft spread) between 200 to 350 yards.  0 to 4ft sure sounds like a small number to be fussing about with all this staggered convergence stuff especially for fighters with wingspans around 30 ft.  This is true of course but only if we're shooting lasers and at targets that aren't trying to maneuver out of the way .

Consider a bogey you're trying to gun down who's traveling at a moderate 225 mph.  That plane is moving at 330 ft/s, or 33 ft every 1/10th of a sec!  The M2 Browning .50 fires at ~800 rounds/min, ~13 rounds/s, ~1.3 rounds per 1/10th of a sec.  Muzzle velocity is 2700 ft/s or 270 ft every 1/10th of sec not factoring drag at all of course which would make a difference as well.  At 300 yards (900 ft) it would take the bullet 3/10th of a second to get to the plane and by then the plane could be 99 ft away from where the bullet was going.  Of course in 1 sec the airplane could be 330 ft away from where the bullet would be.  Of course the higher the forward or angular (turning) velocity, the greater the change in position.  So we can see some of the logic for why staggering gun convergence would make sense to spread the bullets out in area more in order to increase the odds of hitting another moving plane.

Hopefully this gives some insight as to why aircrews chose to use different convergence settings and it appears just like we do in AH it's a matter of preference.  Conceptually trying to land hits at higher speeds and faster maneuvers you might want to spread your gun convergence, but of course you loose the impact of the lethality of a more concentrated burst.

Besides horizontal convergence, people should also remember there's also a vertical component to convergence as well.  For grins, here's the full P-51B gun harmonization chart:



Hope that adds to the discussion!

Tango
412th FS Braunco Mustangs

[Lusche]

Hopefully this gives some insight as to why aircrews chose to use different convergence settings

It does! 

and it appears just like we do in AH it's a matter of preference.  Conceptually trying to land hits at higher speeds and faster maneuvers you might want to spread your gun convergence, but of course you loose the impact of the lethality of a more concentrated burst.

Yes, this is what it all boils down to. And this is, why I do have only one plane with a staggered convergence setting myself: The Me 262. A single hit is usually lethal, but is hard to get because of the very short firing time vs wildly evading fighters, so I'm trying to maximise spread by adopting a staggered setting resulting in a kind of "shotgun effect" (especially if you are taking vertical harmonization into account)

On the other hand, in a plane like the 51, I'm looking for concentration, particularly at long (600+) ranges where the individual round has lost a lot of it's power. The single point harmonization ensures that even at long ranges the probability is high that it's 3 guns (from either left or right wing) that are hitting my target.

[Noah17]

Since what we're really talking about here is maximizing the destructive ability of your shot; whether it's by improving your ability to actually hit someone or if you are a good shot by putting all your rounds in one space, shouldn't we also discuss velocity lost over distance?

Dispersion is one factor but I believe that AH models in the reduction of the velocity of the round over distance and as a result the reduction in it's destructive capability. I have a WWII U.S. "aerial gunnery" manual that says the optimum range for the U.S. .50 cal is 250 yards. This is the most destructive distance to fire at, not the maximum obviously. It also says that firing at over 400 yards is a waste as the destructive capability vs. aircraft is substantially diminished after that range.

We've all gotten kills at ranges at least out to 600yds but, it really does seem to take a lucky or a lot more hits at that range regardless of what my aim/harmonization point is for my .50's. I set my convergence to a single point at 250 and if I can get a good "unloaded" burst at that range it works very well. If it's out to 400 it's still very good but it does seem like it takes a little more.

Does anybody have insight as to how AH does this? Maybe I'm drinking too much and I've imagined it all.......

[Lusche]

Does anybody have insight as to how AH does this? Maybe I'm drinking too much and I've imagined it all.......

You didn't just imagine it
AH accounts for the loss of kinetic energy when shooting at player objects (planes, boats, vehicles), but also factors in chemical energy (explosives) for cannon rounds, which thus have  an advantage at long ranges.

[JunkyII]

I use a a staggered convergence.


The way I see it is I have a fatal funnel coming out the front of my plane(rarely do I shoot past my furtherest convergence so forget that). With a staggered convergence I dont have to be as accurate because my funnel is bigger. I know Im not going to hammer into one spot on a plane but I just cant do that(poor aim). So I spray away at the plane itself hoping for a critical hit or 2.


I dont know if that is just a bad habit but I can knock them down.

 

[Lusche]

I dont know if that is just a bad habit but I can knock them down.

Like having tracers on or off, convergence long/short/staggered this is one of those "whatever works for you" things  

These are mine:

All .50 cal, all cannons (except the Me 262), nose mounted 7.92 (and similar) : 350
Wing mounted .303 (Hurricane I, Spits): 250
Me 262: One pair @200, one pair @600.

[RTHolmes]

interesting that most AH players recommend point convergence, when the manual that tangos pics came from states:

It is found that the type known as "Point Harmonization" does not make the most efficient use of available fire power. In it's place, it is recommended that "Pattern Harmonization" be used; that is, that the fixed guns be boresighted so that their trajectories produce a desirable pattern as near uniform as possible in shape and projectile density over the entire range of fire. A range of 2000 feet is considered maximum for harmonization.

[Lusche]

interesting that most AH players recommend point convergence, when the manual that tangos pics came from states:

We are using many tactics here in AH that weren't recommended in real life.. and they work, for various reasons

For example many AH "vets" are much better shooters within the AH world than our real life counterparts (Partly resulting from having shot literally millions of rounds in combat)

I surely would have used & recommended many different tactics in real life.

[RTHolmes]

yeah I think point favours the more experienced accurate shooters which suggests that AH default should be pattern to give newer players a better chance of landing rounds. iirc Shaw says something along these lines.

[Lusche]

yeah I think point favours the more experienced accurate shooters which suggests that AH default should be pattern to give newer players a better chance of landing rounds. iirc Shaw says something along these lines.

But IMHO it doesn't make much of a difference for the new guys. It probably just increases the number of assists, though of course I can't prove that

That's why I warned a bit in my initial statement about expecting too much from a meticulously devised convergence setting. Unless you really mess it up (setting conv to 150 and shooting at 600+ only), the differences (&gains) are often relatively small, and often pale in comparison to other factors in combat. (Judging angles & speed, giving the proper lead, getting CLOSE, get a feel for crossing shots, using short bursts instead of spraying and so on)

When facing really new players in the TA, I mostly recommended just keeping the default setting and not to worry about it until they really can shoot & hit

[mechanic]

Good stuff to read and learn, thanks guys. Personaly I have always set my guns to point in anything except multiple 30mm and combinations of 30mm and MGs./20s.


With .50s I think it is far better to set the guns to a single point. Here is a quick example why single point convergence should be more effective at long range 800-1000yrds.

The 190 is at around D1.0 flying level and escaping. The single point convergence can be judged to give a chance of landing slightly more concentrated fire on one piece of sky.


The aim point in blue aiming to hit a target at around 900yrds - convergence of 300yrds - will give roughly twice the horizontal spread of fire as the distance between the guns when they're fired.....in theory....as obvisouly there are other divergence physics at play on the rounds also. The rounds must be aimed higher, for starters. Using a staggered convergence would only disperse the rounds farther at this range, which is still within the weapons possible damage distance.



With a bit of luck, a level flying aircraft can be hit at 900-1000 yards by visualising what your convergence will do to the rounds over that distance.


So using any multiple ammount of .50s It is vital to have a point convergence for any long range gunnery, IMO.
S!






 

[Sonicblu]

Im just guessing here but. It might make sense in real life to spread the shot out a little in hopes that any bullet that hits the other aircraft might prove a fatal shot to the aircraft. I.e. the one lucky bullet that hits something vital. I think that the AH model is based on overall damage. So I would think that the more bullets you hit in one spot would do more damage and take a wing off for example where as if you spread them out to much, more  of the aircraft absorbs  the hits with out reaching a lethal point.

Some one let me know if Im wrong.

[Lusche]

So I would think that the more bullets you hit in one spot would do more damage and take a wing off for example where as if you spread them out to much, more  of the aircraft absorbs  the hits with out reaching a lethal point.

That's correct. It's more effective to have your fire concentrated on a single area instead of making single holes all over the plane.

Get close (for better hit probability, less spread and more energy per bullet) and concentrate your fire (if possible on a vital part).