convergence

[mtnman]

hows this one?

(Image removed from quote.)

You can get the bullet trajectory to have a similar path to your drawing if you set the convergence point way in. 

Look at the screen shots I linked to with the 150yd convergence setting.  It behaves similarly to the one you've drawn.  The downside is that in that case once the bullets come up through the LoS they're effectively out of the picture as far as effectiveness goes, because you're going to shoot over the top of anything all they way out past 1000 yards or so, at which point you'll also have a L/R spread of around 120ft (with a big empty spot in the middle).

So, although you can get that type of a trajectory, it'll probably be accidental, ineffective, and non-intuitive (i.e. I'd wager that if you set someone up with a 150yd convergence, they'd compensate for it on a 600yd shot by aiming HIGH, when in reality they'd need to aim LOW...).  They'd also need to aim off to one side as well, when intuitively we're probably more likely to really use the gun sights and refine our aim as much as possible at longer ranges.  Doing that would practically ensure a miss!

[Rolex]

Oh great... mntman is giving away the secrets of gunnery. Now everyone's gonna' be a hotshot.   

(Good to see your text, mntman <S>)

[mtnman]

Oh great... mntman is giving away the secrets of gunnery. Now everyone's gonna' be a hotshot.   

(Good to see your text, mntman <S>)

Ha! 

<S> Rolex!

[Bizman]

Is this more like it?


Original image courtesy of Fugitive

[Slate]

  What's the command in game for showing a target to the north? And what distance is it?

[Lusche]

 What's the command in game for showing a target to the north? And what distance is it?

.target X, where x= desired distance in yards
.target 0 removes target.

[Shuffler]

We 38 drivers have never had an issue with convergence..... are we just smarter or what? 

[bustr]

This is gunnery in a computer program. I've written about this before with all the gunsight tools for offline testing and resulting graphs of impact points at known distances on the offline target.

1. Offline change the arena time to 01:00 so that the white of the target dosent cause your gunsight to dissapere at full zoom.
2. Takoff and head north about 1-2k alt.
3. Allow your fighter to achive max cruise or the speed at which the gunsight center stops dropping on the target at full zoom.
4. The center of your gunsight will drop below the red center line of the target. The center of the target is your fighters center line.
5. Test with your guns set to 150, 250, 350 convergence with the target at 100, 200, 300, 400, 500, 600 yards.
6. If you are using a gunsight that is 512x512 1Mil will equal 2pixel.
7. At each range fire then record how far below or above the gunsight center your rounds pattern. Keep track of the dispersion diameters also.

Here are some results I pulled from the 2.25 release offline.

 ---------------------------------------------------------------------------------------------------------------------------------------

Gunsight Data Collection by: bustr
Aces High 2 ver 2.25 - 8/6/11

Gunsight data collection was performed in (Mil Units) from a gunsight constructed on a 512x512 bitmap mask where 1Mil = 2Pixel. Data was collected at 150, 200, 300, 400, 600 yards. Each aircraft was tested with all guns convergence set to 150, 250, 350. Bullet impact data was collected at each distance in auto level. All values are to the closest whole number due to visual limitations of Full Zoom and dispersion patterning.
----------------------------------------------------------------------------
1Mil @ 150yds = 5 inches
1Mil @ 200yds = 7 inches
1Mil @ 300yds = 11 inches
1Mil @ 400yds = 14 inches
1MIl @ 600yds = 20 inches
---------------------------------------------------------------------------
1.}Pos or neg numbers are relative to the gunsight center(0)& earth(-)=down.
2.)Wing mounted guns cause a 2-5Mil nose drop during extending firing.
3.}HUB cannon fighters, P38, Mosquito, A20 have no nose movement.
4.}A6m have a very small nose movement down when firing.
5.}La5/7 have a 2Mil nose up when firing.
----------------------------------------------------------------------------
Aircraft
P51D - Spit16 - La7 - 190D9 - 109K4 - Yak9U - Typhoon - A6m5 - N1K2J - Ki84  P38J - 109G6 - HurriI
----------------------------------------------------------------------------
P51D -----150-----200-----300-----400-----600-----Auto Level
150------(-2)----(+2)-----(0)----(-1)----(-1)
250------(-2)----(-3)-----(0)----(-1)----(-2)
350------(-3)----(-4)----(-1)----(-2)----(-3)

----------------------------------------------------------------------------
Spit16----150-----200-----300-----400-----600-----Auto Level
150------(-4)----(-2)-----(0)-----(-1)----(-5)
250------(-5)----(-3)-----(0)-----(-1)----(-5)
350------(-5)----(-4)----(-2)-----(-3)----(-5)

----------------------------------------------------------------------------
La-7-----150-----200-----300-----400-----600-----Auto Level
150-----(+2)----(+2)----(+2)-----(0)----(-5)
250-----(+2)----(+1)-----(0)----(-2)----(-6)
350-----(+1)----(+1)-----(0)----(-1)----(-6)

----------------------------------------------------------------------------
190D9----150-----200-----300-----400-----600-----Auto Level
150------(0)----(-1)----(-3)----(-3)----(-8)
250-----(-1)-----(0)----(-2)----(-2)----(-7)
350------(0)-----(0)-----(0)----(-2)----(-7)

----------------------------------------------------------------------------
109K4----150-----200-----300-----400-----600-----Auto Level
150------(0)-----(0)----(-2)----(-5)----(-15)
250------(0)-----(0)----(-2)----(-5)----(-16)
350-----(+1)----(+1)-----(0)----(-2)----(-17)
All data for 109K4 taken from MK108 30mm impact points.
----------------------------------------------------------------------------
Yak9U----150-----200-----300-----400-----600-----Auto Level
150------(0)-----(0)-----(0)----(-1)-----(-5)
250------(0)-----(0)-----(0)----(-1)-----(-7)
350------(0)-----(0)-----(0)----(-2)-----(-7)

----------------------------------------------------------------------------
Typhoon--150-----200-----300-----400-----600-----Auto Level
150------(0)-----(0)-----(0)-----(0)-----(0)
250-----(-2)----(-1)-----(0)-----(0)----(-5)
350-----(-5)----(-2)----(-1)----(-2)----(-5)

----------------------------------------------------------------------------
A6m5-----150-----200-----300-----400-----600-----Auto Level
150------(0)----(-1)----(-1)----(-2)----(-5)
250------(0)----(-1)----(-1)----(-3)----(-6)
350-----(-1)----(-1)----(-1)----(-4)----(-7)

----------------------------------------------------------------------------
N1K2J----150-----200-----300-----400-----600-----Auto Level
150------(0)----(+1)----(+1)----(+1)-----(0)
250-----(-3)----(-2)----(-1)----(-1)----(-4)
350-----(-4)----(-3)----(-2)----(-2)----(-5)

----------------------------------------------------------------------------
Ki84-----150-----200-----300-----400-----600-----Auto Level
150------(0)----(+1)----(+1)-----(0)----(-4)
250-----(-2)----(-1)----(-1)----(-2)----(-6)
350-----(-4)----(-2)----(-1)----(-2)----(-8)

----------------------------------------------------------------------------
P38J-----150-----200-----300-----400-----600-----Auto Level
150------(0)----(+1)----(+1)-----(0)----(-1)
250-----(-1)-----(0)-----(0)----(-1)----(-2)
350-----(-2)----(-1)-----(0)----(-2)----(-3)

----------------------------------------------------------------------------
109G6----150-----200-----300-----400-----600-----Auto Level
150------(0)-----(0)----(-1)----(-2)----(-5)
250-----(-1)-----(0)-----(0)----(-2)----(-6)
350-----(+1)----(+1)-----(0)----(-1)----(-7)

----------------------------------------------------------------------------
HurriI---150-----200-----300-----400-----600-----Auto Level
150------(0)-----(0)----(+1)----(+2)----(-5)
250-----(-2)----(-2)-----(0)----(-2)----(-6)
350-----(-4)---(-2.5)---(-1)----(-1)----(-7)

----------------------------------------------------------------------------

Data Collection Tool.

[DaHand]

We 38 drivers have never had an issue with convergence..... are we just smarter or what? 

 

[bustr]

If you leave the POV on Full Zoom and check from 200-1000 yards with the target (.target xxxx), you will notice that the center of the gunsight stays below the red centerline of the target. This is in all aircraft that use a pilot position gunsight to aim fixed forward firing guns. As you change the convergence the gunsight line is changed slightly to reflect the the IP. But, past Convergence 150 for the most part the gunsight line is below the center line of the target. If you set the target to (.target 7) and use F3 mode you will see the target center is the aircraft center.

You might want to redraw that picture of the P51. Place the center of the target locked with the center line of the P51. Angle the gunsight line down 6Mil below target center at 1000 yards while the ballistic arch of the guns only just touches it from underneath at the convergence point you set from the hanger. From testing I did October of 2010 the numbers came out to the following at 1000 yards on the target.

P51D - convergence - 650
Gunsight Center relative to Target Center @ 1000yds = -6Mil(18ft)
Bullet IP relative to Gunsight Center @ 1000yds = -12Mil(36ft)

Test any fighter by going to full zoom and noteing the relative positions of the target center line to the gunsight center line. As the aircraft is on auto level you can watch the gunsight center drop below the target center line as the plane gets closer to full speed on militairy power.

From my testing your picture may want to look more like this example below. You guys are free to perform your own offline testing and graph the data. I could be completely wrong here.

The 109 has a sweet spot between 150M and 300M where all of the guns should be firing up to 48cm above the gunsight line and dropping back below it about 300-350M per all Bf109F/G/K manuals. Never happens in the game.

I'm not the worlds best artist......but, I can plug numbers into a graph.

[Ardy123]

hmm so basically the AH sight is angled such that the converging point is always below the nose?

[bustr]

I'm agnostic about whether it's authentic or not. The game has been too much fun for me all these years. Snap shots in wing mounted guns might be eaisier with the guns pointing higher to cross a leveled gunsight line while you pull lead. Though you can accomplish that sort of now by pulling your convergence into 150. But, the rounds still never travel higher than the centerline of the aricraft. Just closer to centerline level than say 350conv.

Wonder what would happen to our wing mounted gun gunnery if it was changed to the gunsight view line level and rounds angled up to cross that line while traveling upwards at 300yds? In the manuals that was your vertical convergence. Then they set horizontal convergence or the distance at which they wanted the streams from each wing to cross. I think the center of the gunsight is the key to how we are presented the AH universe.

[The Fugitive]

All this math gives me a head ache! No wonder my aim sucks! LOL!!

So Bustr, what your saying then is that if I'm following a plane flat and level, with the both of us at the same alt I have to aim 6 mil above his plane to get hits, right?

[bustr]

All this math gives me a head ache! No wonder my aim sucks! LOL!!

So Bustr, what your saying then is that if I'm following a plane flat and level, with the both of us at the same alt I have to aim 6 mil above his plane to get hits, right?

In theory if your ponies convergence is 650 and he is 1000 yards away when you fire. But, you will miss if you are in a pony because your streams will probably be wider than his wings if you are aiming dead on him.

Take up a pony offline or a spit or whatever. Let it come up to cruise speed and look at the center of your gunsight every 100 yards from 200-1000. Change the arena time to 01:00 so you can see your gunsight against the target. If the line of sight is level then the center will be above the center line of the target at all distances. You will notice it stays below the center line of the target from 200 out.

It dosent really matter. You still have to learn to get your pipper onto the con how ever HiTech chooses to angle the gunsight line.

[mtnman]

If you leave the POV on Full Zoom and check from 200-1000 yards with the target (.target xxxx), you will notice that the center of the gunsight stays below the red centerline of the target. This is in all aircraft that use a pilot position gunsight to aim fixed forward firing guns. As you change the convergence the gunsight line is changed slightly to reflect the the IP. But, past Convergence 150 for the most part the gunsight line is below the center line of the target. If you set the target to (.target 7) and use F3 mode you will see the target center is the aircraft center.

You might want to redraw that picture of the P51. Place the center of the target locked with the center line of the P51. Angle the gunsight line down 6Mil below target center at 1000 yards while the ballistic arch of the guns only just touches it from underneath at the convergence point you set from the hanger. From testing I did October of 2010 the numbers came out to the following at 1000 yards on the target.

P51D - convergence - 650
Gunsight Center relative to Target Center @ 1000yds = -6Mil(18ft)
Bullet IP relative to Gunsight Center @ 1000yds = -12Mil(36ft)

Test any fighter by going to full zoom and noteing the relative positions of the target center line to the gunsight center line. As the aircraft is on auto level you can watch the gunsight center drop below the target center line as the plane gets closer to full speed on militairy power.

From my testing your picture may want to look more like this example below. You guys are free to perform your own offline testing and graph the data. I could be completely wrong here.

The 109 has a sweet spot between 150M and 300M where all of the guns should be firing up to 48cm above the gunsight line and dropping back below it about 300-350M per all Bf109F/G/K manuals. Never happens in the game.

I'm not the worlds best artist......but, I can plug numbers into a graph.

(Image removed from quote.)

You can fix these apparent inaccuracies by adjusting your throttle.  This will allow you to see rounds that travel above the LoS in their trajectory.  The "trick", is to make your LoS go through the gun sight straight to the center of the target on a level plane.  As soon as you deviate from level, you're going to see problems (they're not really problems, so much as realistic effects that will cause the issues you're seeing).

Keeping your plane at full throttle and allowing the AoA to lower the nose makes it look like the rounds are always going on a downward slope, when in reality they don't always do that.  They look like they are in your test because your LoS is slanted downward.

Simply adjust your speed to keep the sight centered on the bullseye.  Once you figure out the right speed/throttle setting, it'll stay there hands-off.  Of course, firing your guns will have an effect, but that can be almost eliminated by firing in tiny bursts.  If you fire a long stream you'll skew your results...

The effect you're seeing is due to the changing AoA of the wing.  Flying slower requires the wing to have a higher AoA to maintain level flight, flying faster requires less...  Now, you could of course argue that HTC doesn't have quite the correct amount of incidence built into the wing mount, or how that incidence compares to the stabilizer, or that the airfoil shape is slightly (or a lot) off, but that's a whole different can of worms.  Or you could argue that the angle of the LoS isn't quite correct for a given plane (although it would depend on how the plane manufacturer/gunsight-installer set them up in reality).  In reality, the AoA of the real planes would change with speed too, so you'd need to figure out at what speed the LoS was "level", because it would do the same thing it does in AH.  Would the gun-sight be level at top speed?  Or at some lesser speed (maybe based on what they thought the average speed would be while firing?  It's probably not worth going down that path.

Let's stick to the gunnery aspects instead (in this thread at least).

Firing the guns while the LoS will have the effect of flattening the trajectory (max arc across horizontal space will be found with the guns level (which is probably pretty close to where you are with your nose down).  Firing straight up or straight down on the other hand would make the trajectory the most flat.

Firing up or down at an angle also makes the trajectory do some strange things in relation to your LoS as well.  Firing with the LoS vertical straight up would cause the trajectory to quickly cross the LoS (appearing to go way high from your perspective) and they'd never come back "down" to it.  LoS straight down would have a similar visual effect (from the pilots seat).
Firing upside down does some weird things too, very similarly (but more extreme) to firing with the LoS straight up.

The bullets in AH really do fly pretty close to reality.  I originally thought there were some problems too, but I was making the same mistake you are.  It took Rolex and I a while testing in the TA to see where we were making mistakes with the tests that were skewing our results.

Your seeing the beginnings of these effects by doing your test with the LoS on a downward angle.