PDA

View Full Version : RAF Fighter Horizontal convergence



92 Sqn. Philstyle (QJ-P)
Jun-20-2013, 08:38
To add to Farber's excellent work (http://theairtacticalassaultgroup.com/forum/showthread.php?t=4738), something from an RAF flyer's perspective;


https://www.youtube.com/watch?v=pTQHVZ_9iTM

No.54 Ghost (KL-G)
Jun-20-2013, 10:02
been using this setting for a while and it works great.
really good for PKs.

ATAG_Snapper
Jun-20-2013, 12:15
Excellent work, Phil! :thumbsup:

Dutch
Jun-20-2013, 12:47
Superb mate. :thumbsup:

Unfortunately you now have me wondering whether I should re-do my convergences. Anyone know a quicker way than using the GUI, like copy and pasting in a conf file or some such?

LG1.Farber
Jun-20-2013, 13:52
Nice, what program did you use to do that and would you send me the file?

92 Sqn. Philstyle (QJ-P)
Jun-20-2013, 15:40
Superb mate. :thumbsup:

Unfortunately you now have me wondering whether I should re-do my convergences. Anyone know a quicker way than using the GUI, like copy and pasting in a conf file or some such?

copy and paste in the user.ini file - use the file in your "mod" folder.

92 Sqn. Philstyle (QJ-P)
Jun-20-2013, 15:40
Nice, what program did you use to do that and would you send me the file?

just Microsoft excel. it's a spreadsheet.
I'll email a copy to you.

pm me your email addy either here, or from your ACG forums.

Roblex
Jun-20-2013, 16:01
I am not saying you are wrong but...I am always a bit dubious about these 'spread' convergences.

My brain says there are several points where the logic fails:-

1. It is all very well saying 'This set up means the guns converge over a longer range' but you are also saying 'At any distance I am hitting with less guns' or, to put it another way 'I will never be able to hit the target with 8 guns' It's a trade-off; if you are lucky your two guns might hit something vital but they might also just make some harmless holes in the elevators where 8 guns would have totally destroyed the elevators.

2. Everyone uses perfect dead six attacks to explain why the spread method is better but if you are making a perfect dead 6 attack on a target that is not evading then you should not be worrying about what happens when your aim is off as even a crap shot like me can get the shots within 6 inches either way and in such perfect conditions you can open up just before convergence and move a devastating 8-gun sweet spot the length of the target.

3. Most often if you are attacking a fighter then you are making some sort of deflection shot so the diagram is invalid. Rotate that 109 by even 10 degrees to simulate a close tail chase and everything changes and the spread either side of the sweet spot of a tight convergence strategy starts to help. Rotate it by 45 degrees and you have a totally different scenario and, with pulling Gs and guessing lead, your aim is less likely to be accurate anyway.

As I said at the beginning, I am not saying your method won't get you more kills, just that I have doubts about the logic used to justify it.

I should also admit that I don't use a pure 'sweet spot' method myself anyway as I set my convergence to 250 but put the inner guns at 400 based on the (perhaps faulty) logic that there is little difference in convergence angle between 250 & 400 for the inner guns so when I am chasing someone who is 400yds ahead running away in a straight line but I am unable to get closer (which happens a lot) then I can take very careful aim from perfect dead 6 (as my victim thinks he is out of range and does not want to jink in case I get closer) and do enough damage to slow him down or make him jink which also slows him down. At 250 yds the inner guns are still very close together and hitting the fuselage while the other six are converging inside the fuselage. Perhaps my logic as as faulty as the people who like to have four convergence points :D

92 Sqn. Philstyle (QJ-P)
Jun-20-2013, 16:36
My brain says there are several points where the logic fails:-


Every set-up is a trade-off Roblex. Each approach has its own strong points and compromises. The multi-range option helps you play the averages. The spot concentration favours a different approach.

If you're still thinking there is a single optimal then this video isn't for you.

All I'm doing here is showing how different convergence set-ups pan out over range.

Roblex
Jun-20-2013, 17:52
If you're still thinking there is a single optimal then this video isn't for you.
.

Not at all :D How much of dogfighting is at a perfect convergence distance anyway? Perhaps the first bounce. You cannot really control what range you will find yourself at in a twisting dogfight. If you are too close you won't back off to get a better convergence; you will take the shot anyway and perhaps aim to one side to avoid your bullets going either side. Some would say that uncertainty favours your spread method and others would say they prefer knowing most of their bullets are following a known vector they can adjust for away from convergence.

If you spend more time hunting bombers than fighters then I suppose you might spend more time shooting close to a single convergence and that convergence is more likely to be 400yds than 200yds

As I tried to stress in my post, I am not saying you are wrong, I am saying I prefer a different method with different strength and drawbacks. If you were a fan of 18th & 19th century naval warfare you would know that the British Navy liked to use heavy ball shot and aim to make holes in the French hulls, which took accurate shooting, while the French Navy preferred to use chain shot and bring down the masts then board, which took less accurate shooting. Neither was 'right' or 'wrong', just different approaches.

Wulf
Jun-20-2013, 23:01
I tend to agree that there isn't really a right way to do convergence. There are clearly going to be pros and cons no matter what system you use. That said, I nevertheless think it's a mistake to underestimate the importance of the vertical plane and to, for theoretical reasons, attempt to stretch your convergence out based solely on a set of horizontal projections. Although there is no reason, of course, to believe you couldn't configure your weapons to deliver a devastating blow on a target at an extended range, if you look at the trajectory tables for the rounds in question, you will notice that in doing so, it becomes very difficult to hit targets on either side of your convergence.

In my opinion there's a tendency to become overly focused on convergence these days. Until relatively recently, for example, I was quite obsessed with it, and would more often than not attribute my poor performance in air combat to an inability to find the magical convergence 'sweet spot'. If only I could find the the perfect convergence I'd be fine I thought. Well, unfortunately for me, no matter what I tried that magical sweet spot remained elusive. These days I'm not fussed about convergence at all. I simply set convergence to the default. And what that default is I couldn't tell you. I have no idea at all - none! To my current way of thinking it's far more important to get right up close to your target and to shoot only when you are almost on top of him than to fixate on finding the convergence equivalent of the holy grail. As a born again energy fighter, I almost never attack from a dead six position these days. Certainly, I would never attack a bomber in that fashion. Whether I'm targeting bombers or fighters, I like to launch my attacks from above, at an angle of between between about 30 and 75 degrees and shoot a split second before the merge. Sometimes, when attacking an aircraft that is attempting to break hard under my nose, it will be necessary to shoot unsighted, but in all instances the shooting will be done just as close as possible to the target. I've found this method infinitely more successful than co-alt deflection shooting involving range estimation.

Roblex
Jun-21-2013, 03:14
I simply set convergence to the default. And what that default is I couldn't tell you. I have no idea at all - none! To my current way of thinking it's far more important to get right up close to your target and to shoot only when you are almost on top of him than to fixate on finding the convergence equivalent of the holy grail.

Umm... aren't you missing the point of convergence? By all means use the tactic of 'get up close' and don't fixate on getting the perfect distance from your target but leaving you guns aimed at a point 300yds ahead (I believe that is default) while shooting from 50yds means that your bullets will never hit what is in the center of your gunsight, they will always go 5ft either side. If you are getting hits with those settings (other than just hitting mid wing) then either you are not shooting from 50yds or you are doing a lot of high deflection shots and calculating the lead wrong but accidentally getting one wings worth of bullets onto the target because of your error :D

If you only shoot from close range and don't want to bother with 'sweet spots' then I would recommend setting a close convergence but bear in mind that setting a close convergence then shooting at 300yds won't work at all.

92 Sqn. Philstyle (QJ-P)
Jun-21-2013, 04:24
. That said, I nevertheless think it's a mistake to underestimate the importance of the vertical plane and to, for theoretical reasons, attempt to stretch your convergence out based solely on a set of horizontal projections.

You're right. Adding in the vertical dimension does matter.
I have a preference for that too, which is based on

slightly further out vertical convergence for the weapons which horizontally converge close in, and
slightly closer in convergence for the weapons which horizontally convergence further out.


The fact is, I chose to engage aircraft at a multitude of ranges, depending on the situation I find myself in.

As Roblex points out, there's also the added complication of the enemy aircraft's attitude, esp. in the turn... At the dead-6 position a tighter spot convergence is probably more deadly, however, a wide convergence can help against the high-deflection shots becasue the target presented is larger, and you can "rake" his entire air-frame with one burst, scoring hits on engine, cockpit, fuselage and tail-plane all at the same time.

Wulf
Jun-21-2013, 05:05
Umm... aren't you missing the point of convergence? By all means use the tactic of 'get up close' and don't fixate on getting the perfect distance from your target but leaving you guns aimed at a point 300yds ahead (I believe that is default) while shooting from 50yds means that your bullets will never hit what is in the center of your gunsight, they will always go 5ft either side. If you are getting hits with those settings (other than just hitting mid wing) then either you are not shooting from 50yds or you are doing a lot of high deflection shots and calculating the lead wrong but accidentally getting one wings worth of bullets onto the target because of your error :D

If you only shoot from close range and don't want to bother with 'sweet spots' then I would recommend setting a close convergence but bear in mind that setting a close convergence then shooting at 300yds won't work at all.

Hahahahaha .... that's quite amusing. I wish you hadn't told me. :D Are you sure it's 300m? I was just having a look at that German diagram of a Bf 109 incorporated into Farber's video but as I don't speak the German I don't know exactly what it says. Actually, I've never really understood it at all. The convergence appears to be set at 200m BUT above the line of sight. The cannon and MG rounds don't appear to pass through the line of sight until the 400m mark, by which time the cannon rounds are beginning to diverge quite significantly. That seems very strange to me because if you underestimated the range by not very much, you'd miss by a country mile. As for my own shooting, who knows. At present I'm going with the theory that 'the force' is sufficiently strong in me to overcome what, by any standard, would appear to be an unsuitable arrangement for close in shooting. Hmmm ... I'll try and bend a spoon or two and let you know what happens.:hypnotized:

Wulf
Jun-21-2013, 05:19
You're right. Adding in the vertical dimension does matter.
I have a preference for that too, which is based on

slightly further out vertical convergence for the weapons which horizontally converge close in, and
slightly closer in convergence for the weapons which horizontally convergence further out.


The fact is, I chose to engage aircraft at a multitude of ranges, depending on the situation I find myself in.

As Roblex points out, there's also the added complication of the enemy aircraft's attitude, esp. in the turn... At the dead-6 position a tighter spot convergence is probably more deadly, however, a wide convergence can help against the high-deflection shots becasue the target presented is larger, and you can "rake" his entire air-frame with one burst, scoring hits on engine, cockpit, fuselage and tail-plane all at the same time.

Well, I'm a bit the same. Ideally i want to be able to see 'the whites of their eyes' but in reality I guess I'll take any shot that's going, if it appears to have even the remotest chance of success. Connecting on those 90 degree crossing shots is always immensely satisfying - when it happens. :D

92 Sqn. Philstyle (QJ-P)
Jun-21-2013, 05:39
Hahahahaha .... that's quite amusing. I wish you hadn't told me. :D Are you sure it's 300m? :

Roblex is referring to the RAF fighters, not the 109s.
RAF fighters default to 333m I think.

Using my spreadsheet, if you have "default" convergence set in your spitfire, there is little point in shooting at anything (fighters) that is less than 200m away. Even at 150m, the rounds from the inboard weapons (which being about 3.6m from each other) are still approximately 3m apart.

The problem with bringing the convergence right back in for the close-range shots, is that the weapons diverge very, very quickly after that point.

If you set guns 2,3 6&7 to converge at 100m (the minimum allowable in the game) they will be 6m apart at 200m. This force the pilot to make close in shots each, and every time. If you set your out boards to converge at 100m, buy the time they get to 200m they'll be nearly 7m apart.

This is why the inboard weapons should be used for close-in shots, and the outboard weapons for long range shots. It's because of the subsequent DIVERGENCE, not the preceding convergence.

In my opinion, divergence is actually more important than convergence. What are the rounds doing after they converge?

Roblex
Jun-21-2013, 06:51
however, a wide convergence can help against the high-deflection shots becasue the target presented is larger, and you can "rake" his entire air-frame with one burst, scoring hits on engine, cockpit, fuselage and tail-plane all at the same time.

I wont argue with that. In any case once we start talking of high deflection shots all notion of 'concentrated fire' at a specific range goes out the window anyway unless you are very lucky and both methods are probably hitting over a wide area.

ATAG_Snapper
Jun-21-2013, 11:41
Re Phil's convergence chart -- so far seems to work for me. I used the "Long Range" values in your spreadsheet (substituting 100 m for your recommended 80 m only because the ingame GUI sets 100 as the minimum and I was too keen on flying to muck about :D). Most of my engagements were with 109's, with a few AI bombers thrown in.

Because of the deadly accuracy of the AI bombers' gunners, I avoid coming up from behind, preferring medium-deflection shots in angular diving attacks. I extend in a shallow, curving dive before climbing again to rinse & repeat. (This also affords a good look around for any 109's that show up to ruin my fun.). As my fire traversed my target I found that sustained concentrated hits from two-to-four guns more effective than fleeting concentrated hits from all eight guns. Up until now I've had all my guns set to converge at 180 meters (200 yards on my gunsight).

The greatest effect was on the smaller, more agile 109 fighter. As long as I did my part in bringing my guns to bear, the results were more decisive for the rapid variance in range that is endemic to dogfighting. Two or four guns in the engine/cockpit ended the fight quicker than eight guns to both radiators. These are just my initial impressions. As always, YMMV.

ATAG_Knuckles
Jun-21-2013, 13:59
Snapper: I have all guns the same convergence: I would like to try setting some different: Do you have a suggested setting for each of the 8 guns ???

I have all at 250 yards right now:

another thing I really have a hard time "in game" knowing roughly where 250 yards actually is when approaching an aircraft !!!!

Dutch
Jun-21-2013, 15:01
another thing I really have a hard time "in game" knowing roughly where 250 yards actually is when approaching an aircraft !!!!

Hmmm, I can see my explanation in the other thread wasn't very well put......

Here's a couple of screenshots of what your gunsight should look like at 250yds, attacking first a Dornier of 60ft wingspan, then a 109 of 32ft wingspan. See how the horizontal bars on the sight are the same distance apart as the wingspan?

The top ring is set at your convergence, 250yds, the bottom ring is set for the relevant wingspan of first a Dornier, then a 109. :salute:

31433144

ATAG_Knuckles
Jun-21-2013, 16:42
O.K. O.K. wait: errr so when the wing span no wait: err

O.K. so your photo the errr

O.K. now I get it: when your dialed in wing span (bottom ring) fills the sight (horizontal bar) you are at the dialed in (top ring) convergence

Eureka !!! I get it ( after two years of flying this sim) :P

I wonder what else I havent figured out ????

ATAG_Snapper
Jun-21-2013, 18:10
By gawd....I think he's got it! :thumbsup:

Knucks, I'm away from my PC, but later I will post PhilStyle's recommended convergences for each of the eight guns. My first impression is that, for me, they're helpful. I studied his Excel charts carefully to better gain an understanding of what is going on in setting up the convergences in a certain way. If I could guarantee myself that I could maintain an EXACT distance from my quarry before opening fire, then I'd stay with all guns set to the same distance. A good example of this is stalking an unsuspecting victim from behind -- you have all the time in the world to affix his wing tips between the bars of your gunsight reticle before opening fire. (With my luck, his wingmate has all the time in the world affixing MY wing tips in his gunsight reticle!).

Most of my shots are taken on a rapidly closing target OR quick bursts at a rigorously maneuvering fighter at wildly varying distances. For me it works better to have two or four guns on target than eight guns not-quite-on target. I'll post Phil's suggested convergences here later this evening.

Dutch
Jun-21-2013, 19:04
( after two years of flying this sim)

Yeah, but for all of that time, you've been flying a Blenheim. 'Nuff said. The gunsight on the Blen borders on the 'totally useless'. Well, not so much bordering actually! Haha! :thumbsup:

Wulf
Jun-21-2013, 21:26
Have you Spit/Hurri types had a look at the old WW2 RAF publication, 'Bag the Hun'? I noticed someone posted a picture of it on another thread. If you haven't downloaded and read it yet you probably should. It contains some very valuable info on range estimation and deflection shooting.

Dutch
Jun-21-2013, 22:29
Have you Spit/Hurri types had a look at the old WW2 RAF publication, 'Bag the Hun'? I noticed someone posted a picture of it on another thread. If you haven't downloaded and read it yet you probably should. It contains some very valuable info on range estimation and deflection shooting.

Thanks for that mate, I'm sure we'll all bear it in mind. :thumbsup:

Osprey
Jun-23-2013, 06:10
[Knuckles;48367]O.K. O.K. wait: errr so when the wing span no wait: err

O.K. so your photo the errr

O.K. now I get it: when your dialed in wing span (bottom ring) fills the sight (horizontal bar) you are at the dialed in (top ring) convergence

Eureka !!! I get it ( after two years of flying this sim) :P

I wonder what else I havent figured out ????[/QUOTE]

Don't forget that your gunsight is in yards and the game setting is in metres.

92 Sqn. Philstyle (QJ-P)
Jun-23-2013, 08:13
[Knuckles;48367]O.K. O.K. wait: errr so when the wing span no wait: err

O.K. so your photo the errr
.

Alternatively, save yourself a whole lot of nonsense, and ignore the stupid gun-sight and dailing in the range/ wingspans.
If the wingtips of a 109 touch the circle he's close enough to kill.
For bombers, use his engines, instead of wingtips.

That way you never have to fuss about asking "what's the wingspan of a double decker bus".

Meaks
Oct-29-2013, 08:30
I found your chart and video very helpful Phil,so thanks for that:thumbsup:,and I would agree re being close enough on a 109,so not to be too concerned about dialing in the wingspan.

However,talking of being very close to your target,here's something that's always confused me,during the BoB Sailor Malan,made up a list of the 10 rules of air combat,and one of these,the first one infact read:

1. Wait until you see the whites of his eyes.Fire short bursts of one to two seconds only when your sights are definitely 'ON'.

Now,I don't know about you guys but I'll be buggered if I'm going to be positioned where I can see the whites of his eyes before opening fire,especially as he has cannons and mg's in a 109 :thmbdwn:........lol,I want to be behind the bugger....not facing him :hpyflying:

Meaks :salute:

alphapapa
Nov-06-2013, 10:50
Interesting thread. Googled "Bag the Hun" and came up with this Vid


Principles and practise, I'd say! No, that's not a spelling error but an instruction!:thumbsup:

ATAG_EvangelusE
Nov-07-2013, 14:50
Interesting video regards using different horizontal convergence settings.

I notice all the guns in the video use identical vertical convergence values (which differ to the various horizontal values suggested) but not sure 'why'?

Wolger
Dec-18-2013, 21:46
Someone said it' all right not to use the in-flight range and wingspan for weapon convergence setting?

I'd made a list of all planes' wingspan for a quick reference, and their lengths are usually just shorter by a bit so I believe it also can be used for other than direct 6 o'clock attack?

I'm kinda confused and wondering what's the difference between the in-menu convergence setting (I believe it's in metres) and the in-flight range setting (yards), since we can set individual gun convergence in-menu, like say we set the inner 4 guns convergence shorter than outer ones and what will happen if change it again during in-flight?

Skoshi_Tiger
Dec-18-2013, 22:20
The in-flight range setting is for the range of the sight only and does not alter the convergence at all. Ideally you should set the sight range to match the convergence which is a little awkward because as you say the convergence setting is in metres and the sight range is in yards. This means a little bit of calculation is required.

100 yards ~ 91.5m
150 yards ~ 137.2m
200 yards ~ 182.9m
250 yards ~ 228.6m
300 yards ~ 274.3m

Generally I set my sight range 250 yards so before the game I alter the convergence to 228.6 metres. I saved my convergence of course, but you still have to set up the sight each mission.

But like to said you can't set the wingspan of the sight completely accurately for aircraft so there is some room for errors. I've taken the attitude of close enough is good enough.

Hmmm, I've never tried it but I wonder if is possible to set the wingspan to an axis then it might be possible to go inbetween steps??????


Cheers!

Wolger
Dec-18-2013, 22:45
The in-flight range setting is for the range of the sight only and does not alter the convergence at all. Ideally you should set the sight range to match the convergence which is a little awkward because as you say the convergence setting is in metres and the sight range is in yards. This means a little bit of calculation is required.

100 yards ~ 91.5m
150 yards ~ 137.2m
200 yards ~ 182.9m
250 yards ~ 228.6m
300 yards ~ 274.3m

Generally I set my sight range 250 yards so before the game I alter the convergence to 228.6 metres. I saved my convergence of course, but you still have to set up the sight each mission.

But like to said you can't set the wingspan of the sight completely accurately for aircraft so there is some room for errors. I've taken the attitude of close enough is good enough.

Hmmm, I've never tried it but I wonder if is possible to set the wingspan to an axis then it might be possible to go inbetween steps??????


Cheers!

Thanks Skoshi_Tiger. That really clears things up. I'll test various settings like inner guns to shorter or longer convergence.

9./JG52 Mindle
Jan-30-2014, 05:03
Made an exel chart myself after reading this thread, sems like fun so why not?

Anyway, after being a dodgy aim at best and usually going 200m/200m on all guns, I tried what ended up being a small box type setting, using a small vertical component also, not quite point convergence.

I seem to be getting a better return in dogfights (as my aim is still pretty crap), as i think this setting gives me a little more latitude than pure point conv, but still lands a good weight of fire too. In theory it gives fuselage hits between 125m - 200m, most concentrated between 160m - 180m, where i tend to end up shooting from most of the time. I need to get within 180m of bombers though so need to duck and dive a little.

Just thought i'd share it. :thumbsup:

1&8: 180m / 180m - Tr, DW, DW, DW, AP, AP, AP, AP
2&7: 170m/170m - DW
3&6: 160m/160m - AP
4&5: 150m / 150m - AP, AP, AP, AP, Tr, DW, DW, DW

:salute:

Kling
Jan-30-2014, 05:46
Made an exel chart myself after reading this thread, sems like fun so why not?

Anyway, after being a dodgy aim at best and usually going 200m/200m on all guns, I tried what ended up being a small box type setting, using a small vertical component also, not quite point convergence.

I seem to be getting a better return in dogfights (as my aim is still pretty crap), as i think this setting gives me a little more latitude than pure point conv, but still lands a good weight of fire too. In theory it gives fuselage hits between 125m - 200m, most concentrated between 160m - 180m, where i tend to end up shooting from most of the time. I need to get within 180m of bombers though so need to duck and dive a little.

Just thought i'd share it. :thumbsup:

1&8: 180m / 180m - Tr, DW, DW, DW, AP, AP, AP, AP
2&7: 170m/170m - DW
3&6: 160m/160m - AP
4&5: 150m / 150m - AP, AP, AP, AP, Tr, DW, DW, DW

:salute:

Ive done this for a looong time with great results. Although I start at 210m and go down to 170m but the principle is the same.

My brother claimed he couldnt hit at all when he attacked planes, especially non manovering targets, and I told him to try this setup and now suddenly he is downing planes left and right...

9./JG52 Mindle
Jan-30-2014, 06:55
Cool..

I will set up for 200/190/180/170 also and see which feels best for me, but i tend to try and get in quite close as my long shot isn't to scratch yet!!

:doh:

92 Sqn. Philstyle (QJ-P)
Jan-30-2014, 10:27
If you're going to step the horizontal convergence in, you should ideally keep the vertical convergence the same for all guns.

With a 200-190-180-170 horizontal setup (from outside to inside), I would recommend about ~220m on the vertical. This will keep all your ammunition "up", and prevent the guns on the inside (near the wing root) from dropping short.

I personally use 350m on the vertical on all guns. This gives me a bit of extra deflection when turning. (i.e. the guns fire slightly high, above close-in targets)

9./JG52 Mindle
Jan-30-2014, 11:04
Agreed. But if the guns fire 'up' from the level of the wings to cross the eyeline at 200m wouldnt they be lower at H150m/V200m than if set at 150m/150m? If that makes any sense?

The parabolic arc over such a short distance 'up' to line of sight would be pretty much a straight line (i think?) so the vertical displacement would be quite small between guns, a couple of feet?


Easy to confuse yourself trying to picture this....

92 Sqn. Philstyle (QJ-P)
Jan-30-2014, 11:40
Agreed. But if the guns fire 'up' from the level of the wings to cross the eyeline at 200m wouldnt they be lower at H150m/V200m than if set at 150m/150m? If that makes any sense?

The parabolic arc over such a short distance 'up' to line of sight would be pretty much a straight line (i think?) so the vertical displacement would be quite small between guns, a couple of feet?
Easy to confuse yourself trying to picture this....[/QUOTE]

Yes, and no! You're entirely right to wonder about this. It depends on how parabolicy (? real word ?) the arc is!
Let's draw some pictures!

I shall reply with some soon.

9./JG52 Mindle
Jan-30-2014, 11:47
Cool..

:D

I am guessing its about what g load you are under when firing. I try and pull a little lead and then release the g a lot before pulling the trigger. But i am pretty much a beginner and i am happy with hitting anything to be honest.

92 Sqn. Philstyle (QJ-P)
Jan-30-2014, 12:11
Right, so now we're onto verticals!

Vertical seems easy than horizontal.. but it's not...
Take a look at the image.

7203

The red dashed line represents the Angle of Attack (AoA), based on the gun-sight, set to the pilot's eye level.

In the first two cases, it looks obvious, the differences between a 200m and 150m convergence.
HOWEVER, have we got the parabolic arc correct? Probably not.
What if the GREEN line in the third image actually represents the 150m convergence? Does the shorter convergence actually cross the AoA twice?

What about a 300m convergence setting (3rd example)? How quickly do the bullets fall away, when set to converge at such range?
Should the cross the AoA twice also, once before 300m and once again at 300m?

To build a working graphic of Vertical convergence you need to factor in gravity. However, the direction of gravitational force on bullets fired at a 45 degree-up angle, will be different to bullets fired parallel to the ground.

Ballistics in the vertical (with a variable Angle of Attack) are very, very difficult to work out.

Kling
Jan-30-2014, 12:35
Its all about having a good spread when shooting at a target. Since 109 rads are so vunerable, a good spread(box convergency) will do the trick as well as "point convergency "(small spread). Aiming becomes less of an issue and I really would recommend to have spread vertical comvergence as well...

But everyone has their own way of doing things...

92 Sqn. Philstyle (QJ-P)
Jan-30-2014, 13:05
Its all about having a good spread when shooting at a target. Since 109 rads are so vunerable, a good spread(box convergency) will do the trick as well as "point convergency "(small spread). Aiming becomes less of an issue and I really would recommend to have spread vertical comvergence as well...


Or the alternative is to do what the crack-shot RAF pilots did.

Set it short. And ONLY shoot when you are really, really close in. We're talking 30-50m here. You cannot miss at 50m.

P/O N. Agazarian, 26 September 1940:
It zoomed and I followed getting in a short burst from about 400 yards. I then gave my machine full throttle and revs and caught up the 109 hand over fist. When about 50 yards away and directly behind I gave him the rest of my ammunition. He went on to his back and spun down

P/O John Freeborn, 24 May 1940:
As I dived to ground level I throttled back slightly and the e/a on my tail over shot me and I was able to get a three seconds burst at a range of about 50 to 100 yards. He seemed to break away slowly to the right as though he was badly hit and I think he crashed

F/Lt Robert F. Boyd, 18 August 1940:
They proved to be Me 109's which chased me back to coast, one continuing chase after others had left me: on seeing this I went into a turn, got onto its tail closed to 70 yards and fired 2 second burst. I saw this A/C hit the sea in flames..

Sgt Jack Stokoe, 1 September 1940:
I executed a steep turn, pushed in boost override, and sat on his tail. At about 50 yards, I gave him one small burst with little effect, closed to 30 yards, and gave a slightly longer burst. Black smoke poured from him as I overshot him. The a/c crashed in a field, turned over two or three times and burst into flames in a clump of trees. 70 bullets were fired from each gun.
(70 rounds is about 3.2 seconds of fire for the spitfire's and hurricane's browning - so we're probably looking at a 1-second, followed by 2-seconds burst).

9./JG52 Mindle
Jan-30-2014, 14:27
The vertical element i guess is always going to heavily influenced by AOA, turn rate etc. That's why i use tracers, it gives me at least a chance of hitting something in my usual twisty-turny encounters.

I will certainly mess about with different vertical settings until i have one thats suits the way i fly most of the time.

Thanks both for the input. :thumbsup::thumbsup::thumbsup:

Kling
Jan-30-2014, 15:13
And of course as Philstyle said, nothing will ever be better than getting very close in as your bullets are more devastasting the closer you get!! ;)

Problem is that when you get really close (if you are right behind his dead 6) you will have to choose only one wing to aim with because if you have the gunsight on your target your bullets from your left wing will pass on his left and the bullets from your right wing will pass on his right. So you will have to use rudder and choose one wing and hit your enemy with the bullets from that wing alone.

Although its only half of your armament, it is well compensated by the fact that you are so close that the rounds are twice as devastating!

Wulf
Jan-30-2014, 19:46
Right, so now we're onto verticals!

Vertical seems easy than horizontal.. but it's not...
Take a look at the image.

7203

The red dashed line represents the Angle of Attack (AoA), based on the gun-sight, set to the pilot's eye level.

In the first two cases, it looks obvious, the differences between a 200m and 150m convergence.
HOWEVER, have we got the parabolic arc correct? Probably not.
What if the GREEN line in the third image actually represents the 150m convergence? Does the shorter convergence actually cross the AoA twice?

What about a 300m convergence setting (3rd example)? How quickly do the bullets fall away, when set to converge at such range?
Should the cross the AoA twice also, once before 300m and once again at 300m?


To build a working graphic of Vertical convergence you need to factor in gravity. However, the direction of gravitational force on bullets fired at a 45 degree-up angle, will be different to bullets fired parallel to the ground.

Ballistics in the vertical (with a variable Angle of Attack) are very, very difficult to work out.



This may or may not be of some assistance to you Red chaps.

For a 400 yard zero (that is, for a 400 yard convergence point) Mk VII .303 ammunition will have the following trajectory.

100 yards - 13 inches above line of sight (LoS)
150 yards - 16 inches above LoS
200 yards - 18 inches above LoS
250 yards - 17.5 inches above LoS
300 yards - 15 inches above LoS
350 yards - 7 inches above LoS
400 yards - zero inches above or below LoS
450 yards - 13.5 inches below LoS
500 yards - 30 inches below LoS

92 Sqn. Philstyle (QJ-P)
Jan-31-2014, 04:05
This may or may not be of some assistance to you Red chaps.

For a 400 yard zero (that is, for a 400 yard convergence point) Mk VII .303 ammunition will have the following trajectory.

100 yards - 13 inches above line of sight (LoS)
150 yards - 16 inches above LoS
200 yards - 18 inches above LoS
250 yards - 17.5 inches above LoS
300 yards - 15 inches above LoS
350 yards - 7 inches above LoS
400 yards - zero inches above or below LoS
450 yards - 13.5 inches below LoS
500 yards - 30 inches below LoS

Beautiful Wulf.

Can I ask where you got this?
Is there a calculator or something that can be used to enter variables into?

9./JG52 Mindle
Jan-31-2014, 07:37
Would be interesting to see trajectories at 200m V and 300m V too.

A (somewhat) rough plot of that flight path is intersting. If you flatten that arc a little to represent aiming 'up' for a 200m vertical convergence rather than 'dropping' them on a point 400m away, it shows the bullets travelling pretty much along the line of sight all through the killing zone 150m - 225m ish. I can't imagine you can 'drop' the bullets onto a 200m distant point, too near, surely the bullets will have to track 'up' to that point.

Of course, all things being equal, straight and level flight etc, which hardly ever happens in a dogfight. Sort of makes the finer details moot.

Again, i like the visual clue of the tracer to see if i have bullets along LOS at shooting range but its certainly interesting.,:thumbsup:

Wulf
Jan-31-2014, 09:16
Beautiful Wulf.

Can I ask where you got this?
Is there a calculator or something that can be used to enter variables into?



Hi Phil

I extracted the above from a shooting forum site. It was provided by someone with a Vickers MG elevation calculating slide rule. Unfortunately it was the only example he gave.

However, if you go to the site listed below and have a look at the available reference material on the left hand side of the page you'll see a reference to "Manuals". If you click on that it should take you to copies of various original Vickers MG manuals including a number of "Range Tables" for the .303 Vickers, which, with a bit of luck, should provide you with the information you're after.


http://www.vickersmachinegun.org.uk/

92 Sqn. Philstyle (QJ-P)
Jan-31-2014, 09:19
Hi Phil
I extracted the above from a shooting forum site. It was provided by someone with a Vickers MG elevation calculating slide rule. Unfortunately it was the only example he gave.
However, if you go to the site listed below and have a look at the available reference material on the left hand side of the page you'll see a reference to "Manuals". If you click on that it should take you to copies of various original Vickers MG manuals including a number of "Range Tables" for the .303 Vickers, which, with a bit of luck, should provide you with the information you're after.
http://www.vickersmachinegun.org.uk/

Cheers mate. Will take a look.

Although, the verticals for a fixed weapon, pointing paralleled to the ground (without turning, or angles of attack) will be different from an aircraft.

9./JG52 Mindle
Jan-31-2014, 09:56
Think i'm goning to try your idea Phil and keep the staggered H conv but set V conv to 200m.

Wulf
Jan-31-2014, 09:58
Cheers mate. Will take a look.

Although, the verticals for a fixed weapon, pointing paralleled to the ground (without turning, or angles of attack) will be different from an aircraft.


I can't see why that would be. With a WW 2 fighter aircraft you have fixed forward-firing weapons zeroed to a predetermined range (convergence). That's no different to a MG on a heavy mounting sighted in so that the fall of shot strikes the ground at a certain range. The only real difference between the two is that, in the latter case, you can change the zero (by raising or lowering the elevation of the gun) to coincide with the known range of your target, rather than having to physically move the MG to a fixed distance from the target in order to engage it, as is the case with a 109 or Spit. In the end it all comes down to the known trajectory of the ammunition in question. As the Vickers and the Browning both use the same ammo, the trajectories or the respective weapons will be for all practical purposes, identical.

9./JG52 Mindle
Jan-31-2014, 10:34
I need a lie down.

:stunned:

9./JG52 Mindle
Feb-16-2014, 06:11
After a lot of experimenting..

I like Philstyle's recommendation for a long vertical convergence. It does help in a turn and keeps the bullets along the LOS for a longer time.

I have settled with H 183m (200y) as this is my favoured engagement distance, perhaps with guns staggered at 10m intervals, and V 320m (350y), anywhere from 300 - 350m is good.

Now, practice, practice, practice!!

Thanks guys! :thumbsup:

Otyg
Feb-17-2014, 22:49
As a fairly new player I use 150/600 on all eight guns. I started at 150/400 but 600 felt better. And I'm doing fairly good with it.
I'm still only firing up close but in a tight turn I feel I don't have to lead as much to hit and therefore don't lose visual if the twisting and turning bandit.
But that's just me.

Catseye
Feb-18-2014, 18:14
As a fairly new player I use 150/600 on all eight guns. I started at 150/400 but 600 felt better. And I'm doing fairly good with it.
I'm still only firing up close but in a tight turn I feel I don't have to lead as much to hit and therefore don't lose visual if the twisting and turning bandit.
But that's just me.

You are on the right track. :)

It allows for less lead in a turning fight and . . . . . . an issue I take advantage of is that the rise of the bullet above the center line when the target is say 200 yds, is much much less than when you have your sights set for exactly 200 yds where if the target is then closer or further than the 200, your shells lob either too high or fall off quickly.

Setting at 600 yds allows for less rise and fall for tgts between 150 and 400 yds. and will reach out for a longer distance if required. However . . . I have my horizontal set for 225 yds which means that I can reach out to 400 yds and still be within the wingspan of my tgt.

Has worked for me for some time now.

Cheers,
Cats . . . . .

DeXaÏ_☨
Feb-20-2014, 14:35
/!\ USE LATEST VERSION /!\

Hi guys,

I generated an Excel calculation tool for vertical (Y) and horizontal (X) convergence for the spitfire MkI (MKII should work as well).

It took me much, much more time than I expected, but it's a good training for my work... and I'm quite a nerd, so I persisted ;)

This calculator was created by extracting data from the JBM ballistic calculator (http://goo.gl/jlHHYT).

You can find the setup here (http://goo.gl/bGA7iT) (I modified the "zero range" to simulate different convergence setups).

I'm not sure how the game handles ballistics, so my model "should" be reasonably accurate Vs real life, but may not be perfectly representative of the "in-game".

From the JBM data, I ran a heavy polynomial regression (^8) which gave a very high accuracy for the drop (less than 0.05 yd variation with the model in Y, 0.00 variation in X, at 2000 yard (Z)). So I think we're safe on this side. The drawback is that distance needs to be expressed in tens for the "view on target" charts (poka yoke implemented in the calculator, no mistake possible).

I also included bubble charts, which provide the uncertainty in accuracy (deviation of 3MOA). Be aware that your Excel version might mess up the bubbles scale. (discontinued from F0.1 on)

It could be improved with :
A "lethality envelope" which would give a mapping of how many guns you have on target function of distance and settings. Done 21 02 2014, from V3 on
A reverse calculator, which would give the setup to achieve a shot at a specific location (X,Y,Z). Done 28 02 2014, from F1.0 on
Generating something similar for Hurricanes.
Perforating capacities at given distance Vs Steel, Vs Aluminum...
...

Limitations :
It only works with the nitrocellulose rounds (Ref. ending with "z") which had a mass of 175gr, initial velocity around 740m/s and a ballistic coefficient of 0.467 G8 (flat base). DeWilde and AP are nitro powered so they work, but balls do not match exactly (.303 MkI wouldn't fit after few hundreds yard).
It works in "static" = no deflection, no AoA, distances are considered constant. Like if you were in a plane fixed on the flat top of a mountain at 8000ft, aiming at a carboard Bf109 silhouette at given distance, with a 100mph headwind.
X and Y are calculated independently (in case I made a mistake, it might be harder to spot).

How does it work :
Check vids.
Enter your convergence setup in the chart, top of the "calculator" tab. On the same page, enter at which distance charts should display the target (all those boxes are in light yellow).
V Conv from 100 to 1000m
H Conv from 100 to 1000m
Chart data from 10 to 2000 yd (outdated, see vids)

First video to introduce the calculator
0:00 How was the calculator made
1:54 Limitations
3:36 Presentation of the features
7:48 Points of interest


https://www.youtube.com/watch?v=ZY-NmiAkJBY


Second video covers the practical aspects through an example and how to use the calculator to set the convergence which would suits you best
0:00 Reverse calculator to set H Conv
5:17 Vertical Convergence
7:28 Guns on Hitbox charts
8:41 View on Target charts


https://www.youtube.com/watch?v=9nl04vR6EtQ


Et voila !

Give me your thoughts, and if you spot a mistake, thanks for letting me know.

Calculator can be found here :
V1 : http://goo.gl/9xed8A [superseded]
V3 : http://goo.gl/rdDuzl [superseded apart from the MOA bubble charts]
F0.1 :http://goo.gl/1PxYkD [superseded]
F1.0 :http://goo.gl/TPlulw (Reverse calculator for H Conv, MOA Scale added. Used for the videos. Inaccuracy in V conv)
F2.0 :http://goo.gl/6ApWnZ (Considers convergence with gun location, seems not correct)
F2.2 LOS : http://goo.gl/3NStKs (Convergence with LOS + latest updates. V Conv hypothesis still needs confirmation).
F2.3 LoS : http://goo.gl/jexGQi (Final Version - Convergence with LoS for each gun + ToS and Velocity data added).

Cheers !

/!\ USE LATEST VERSION /!\

9./JG52 Mindle
Feb-22-2014, 09:13
Thanks mate. This really helps make sense of vertical displacement and groupings at different convergences.

I am liking 183m hor & 400m vert :thumbsup::thumbsup:

9./JG52 Mindle
Feb-22-2014, 09:36
Can't see a G1 bubble on chart 3:salute:

DaisyDuke
Feb-22-2014, 16:48
Right, I'm confused now. Do you set the gunsight to the vertical convergence range or the horizontal? Sorry ignore this, I've got it.

DeXaÏ_☨
Feb-22-2014, 16:53
Thanks mate. This really helps make sense of vertical displacement and groupings at different convergences.

I am liking 183m hor & 400m vert :thumbsup::thumbsup:


Thanks for the feedback Mindle !

I compiled another version. I had to get rid of the bubble chart (and the MOA) because they couldn't be customized to display an image to scale (Bf109 silhouette). I don't think it's a big loss, and the V3 is still online if needed.

This new version includes:
- The possibility to offset the target (if the target is outside your envelope, you can slide to align only one wing guns on it).
- Display the gunsight spacing (if you want to use the gunsight side bars as a secondary sight. Be aware that the perspective was not implemented : on the "view on target" charts, it considers your gunsight range is matching the chart value).
- Improved interface, everything is up and down the input charts. Charts aligned and scaled.
- Debug : Bf109 silhouette is scaled, hitbox improved, missing G1 dot is included.

New version here : http://goo.gl/1PxYkD [F0.1]

=FI=Murph
Feb-23-2014, 18:08
And the other thing we need to consider is that the convergences in the game's GUI are in meters, and the range settings for the British gun sights are in yards. I like having my convergence set to 220 meters for all guns both vertical and horizontal, and I guesstimate that to be roughly equivalent of 180 yards?

9./JG52 Mindle
Feb-25-2014, 05:53
Hi DaisyDuke

Set your gunsight to horizontal convergence distance: Mine is set to 200 yards (183m on the loadout page). You want to engage close to this distance if possible. Set the wingspan of your target into the sight also. e.g. 32ft for a 109.

Adjust sight left / right alters the horizontal crosshair for matching enemy wingspan.

Adjust sight distance sets your sight distance for the wingspan to be correct at your ideal convergence distance.. in my case 200 yards (183m that i have my guns horzontal conv set to).

9./JG52 Mindle
Feb-25-2014, 06:23
Murph

1m = 1.094 yards

183m = 200yards

200m = 219 yards

220m is 240 yards

250m = 273 yards

http://www.convert-me.com/en/convert/length/

DaisyDuke
Feb-26-2014, 05:08
Hi DaisyDuke

Set your gunsight to horizontal convergence distance: Mine is set to 200 yards (183m on the loadout page). You want to engage close to this distance if possible. Set the wingspan of your target into the sight also. e.g. 32ft for a 109.

Adjust sight left / right alters the horizontal crosshair for matching enemy wingspan.

Adjust sight distance sets your sight distance for the wingspan to be correct at your ideal convergence distance.. in my case 200 yards (183m that i have my guns horzontal conv set to).

Awesome, thanks for clearing that up Mindle :)

DeXaÏ_☨
Feb-28-2014, 12:47
Hello everyone,

Please find below the latest version of the calculator.

This version is updated with :
- A MOA scale on the "view on target" charts.
- You can also set the MOA (3-4 recommended).
- A reverse calculator for H Conv, in which you enter where you want your bullet to hit, and the calculator gives you the recommended setup.
- Gun intersects on charts.
- Gun intersects locations (X and Z coordinates).
- Inverted scale for X to simulate top view and improve consistency with other charts.
- Debug and small scale improvement.

I'm quite satisfied with the features the calculator provides, so I think I won't modify it much further. Nonetheless, if you were to spot a problem, let me know and I would correct it. Also, if you have any recommendation, comment or question, feel free to post it here or through PM, and I'll see what I can do.

I'm also considering making a tutorial video to explain how the calculator works and give some tips and tricks on how to set the convergence.

So far, the different calculator versions have been downloaded more than 50 times. So thank you all for your trust.

Calculator can be found here : http://goo.gl/TPlulw

Cheers !

DeXaÏ_☨
Mar-01-2014, 12:07
Hello everyone !

Please find below the videos which explains how the calculator works.
For the practical aspects of the calculator and how to use it, you can directly jump to the second video. I recommend watching the first video as well though, as it'll help understanding the problematic and gives a better understanding of the second video.

I'm sorry for the sound on the second vid, but it was such a pain to make those videos, that I don't feel like doing it again. I'd recommend to use headsets or to lower your bass to pick up the voice more clearly.

/!\ Calculator version F1.0 used for the videos, V conv modified from version 2.0 and on /!\
First video to introduce the calculator
0:00 How was the calculator made
1:54 Limitations
3:36 Presentation of the features
7:48 Points of interest


https://www.youtube.com/watch?v=ZY-NmiAkJBY


Second video covers the practical aspects through an example and how to use the calculator to set the convergence which would suits you best
0:00 Reverse calculator to set H Conv
5:17 Vertical Convergence
7:28 Guns on Hitbox charts
8:41 View on Target charts


https://www.youtube.com/watch?v=9nl04vR6EtQ


Et voila !

Cheers !

Roblex
Mar-01-2014, 13:36
Well if it is accurate it has brought up a very interesting issue....when my guns are set to 183m and I find myself 50m behind that 109 then I need to aim at least 18 inches higher! So those times I have though 'I can't miss at this range' I have probably been shooting way under. Luckily, aiming 18 inches above the left radiator put three guns onto the right.

It also shows that the vertical convergence of 550 is not significantly different from 183m.

ATAG_EvangelusE
Mar-01-2014, 15:12
Very impressive and I will certainly try the calculator. Thanks for the video as they really do help!

DeXaÏ_☨
Mar-02-2014, 03:35
Well if it is accurate it has brought up a very interesting issue....when my guns are set to 183m and I find myself 50m behind that 109 then I need to aim at least 18 inches higher! So those times I have though 'I can't miss at this range' I have probably been shooting way under. Luckily, aiming 18 inches above the left radiator put three guns onto the right.

It also shows that the vertical convergence of 550 is not significantly different from 183m.

Hi Roblex,

Thanks for the feedback !

The accuracy of the calculator should be very fine at close range. It would only be a minor concern at range above 500 yards combined with extreme convergence setup (100 or 1000yd). At 2000yd, even with extreme setups, I achieve <0.05yd inaccuracy (below 1.8 inches).

I had the same problem as yours with very close range, I didn't get it at first, but I pictured it while doing the calculator : it's coming from the fact the gunsight is much higher than the gun : at close range (<100yd), the central point of the gunsight is "useless".
Like trying to shoot at point blank with a sniper : the bullet cannot hit where the scope dot is aiming (here, our scope is ~42in up the barrel...).

V Convergence between ~200 and ~600yd can even give exact same drop curve if picked carefully : For short V Conv, the bullet will cross the center line while going up, for long V conv, while the bullet is going down. Carefully picked long or short V Conv can actually achieve the (almost) same drop curve.
To go further, I'd recommend setting quite "straight" V convergence (the one making the drop range the lowest, ~340m) : the only parameter which generates this drop, is gravity. if you follow a 109 in a vertical dive/climb, the offset with your centerline (usually called drop, but in vertical it doesn't make sense to call it like that anymore) will increase, but with flat trajectory, this will be less important (you'll have to place the target slightly above your gunsight point though).
issue solved from version F2.0 and on


Very impressive and I will certainly try the calculator. Thanks for the video as they really do help!

Great, thanks ! Have fun and if you have any question or comment, please let me know !

Roblex
Mar-02-2014, 08:14
You misunderstood me DeXal. I was not pointing out a bug in the program, I was saying it pointed out an error I have been making when close on someones tail i.e. all my shots were probably going under him!

This is probably a good thing to know for another reason. When you find you are about to overshoot your target, there is a fatal temptation to keep your nose on him just a bit longer than is safe just to get some more bullets in at close range before you pass. Now I know that my bullets are probably hitting at least 18 inches lower then I can aim just over his canopy and be less likely to collide.

It also solved a recent debate on another forum about whether it helps to set your Vertical Convergence to 550m even though your Horizontal is set at 183 in British fighters. People keep saying it allows you to better hit targets at extreme range while not affecting your close in shooting and it also helps in turnfights by giving more lead. If this program is accurate then the answer is a resounding no. Before any LW pilots jump in, Yes your 109 cannons are a very different matter as they need a much higher trajectory.

REQUEST:-

Your charts showing where the bullets will hit at different ranges have the gunsight markings fixed as if you are looking at the target from exact convergence range i.e. when I set my gunsight so the 109 fits exactly between the bars (or dots on your chart) at 200yds your chart still shows it fitting exactly at 400yds. Would it not be more useful if those dots were moved out as the range increases so we can see how the target will actually look in the gunsight at longer ranges i.e. if my gunsight is set for 200yds then at 400yds the yellow dots should be twice as far apart. Obviously at much longer ranges the dots will not even show on the chart but I cannot see what use they are serving currently as they are just *wrong* You may ask 'What use what adjusting the dots serve?' Well it may be that your particular convergence settings mean that at 400yds putting the left dot/bar-end on the target means the bullets from one wing will hit the target exactly because of their divergence. Just a thought, possibly flawed.

DeXaÏ_☨
Mar-02-2014, 14:53
You misunderstood me DeXal. I was not pointing out a bug in the program, I was saying it pointed out an error I have been making when close on someones tail i.e. all my shots were probably going under him!

Ok, noted. No problem anyway ! :)


It also solved a recent debate on another forum about whether it helps to set your Vertical Convergence to 550m even though your Horizontal is set at 183 in British fighters. People keep saying it allows you to better hit targets at extreme range while not affecting your close in shooting and it also helps in turnfights by giving more lead. If this program is accurate then the answer is a resounding no. Before any LW pilots jump in, Yes your 109 cannons are a very different matter as they need a much higher trajectory.

Yes, I heard that as well and refer to this "urban legend" in the videos. To me, 750m in V Conv, considering you aim at the bottom part of the 109, would be the maximum (bullet hitting the top of the canopy). Moreover, in a dive or climb, the "tougher" the V Conv (very short or very long V Conv), the more your bullets will spread (less influence of the gravity).
Actually, it is too bad you cannot set your point of impact as they were doing it in real life (on a "poster"/mount (http://ww2today.com/wp-content/uploads/2013/04/Spitfire-gun-harmonisation.jpg), located at a given distance). If my observations are correct, you cannot aim under your line of sight (all bullets will cross your line of sight, that's why I recommend to place the target just above your gunsight central point, to counteract that). It's really too bad the game developers didn't implement a convergence under your line of sight, that would have partially solved those "at short range, aim above target, medium under and long above again"...


Your charts showing where the bullets will hit at different ranges have the gunsight markings fixed as if you are looking at the target from exact convergence range i.e. when I set my gunsight so the 109 fits exactly between the bars (or dots on your chart) at 200yds your chart still shows it fitting exactly at 400yds.

Yes. I hesitated to put the gunsight on the "view on target" charts. As the little warning on the top of the chart is saying, and as per your observations, the range (on the gunsight) is set "as if" it was always matching the "view on target" specific distance.


Would it not be more useful if those dots were moved out as the range increases so we can see how the target will actually look in the gunsight at longer ranges i.e. if my gunsight is set for 200yds then at 400yds the yellow dots should be twice as far apart.
Obviously at much longer ranges the dots will not even show on the chart but I cannot see what use they are serving currently as they are just *wrong* You may ask 'What use what adjusting the dots serve?' Well it may be that your particular convergence settings mean that at 400yds putting the left dot/bar-end on the target means the bullets from one wing will hit the target exactly because of their divergence. Just a thought, possibly flawed.

Well, I didn't implement it, because the reflex gunsight was quite cryptic to me ;) Moreover, I thought the FOV was having an impact on the perspective (which is true, but apparently not a problem in our case). But after seeing your post, I read a bit about perspective and it seems to be much simpler than I expected. So I'll implement it soon !

Cheers !

Roblex
Mar-03-2014, 03:06
Not a complaint, just clarifying how it is supposed to work, but is the 'Reverse Calculator' designed to only calculate hits *after* convergence?

I tried to calculate what convergence would pass through the radiator regions at 200yds and converge further on and it insisted on making it converge between me and the target then hitting the rads after. In the end I just did it by trial and error. My reason for doing this was that I usually open fire on fighters at 200yds but when attacking a bomber 200yds is a bit close. I now have a setting that makes a fairly tight, slightly horizontal, grouping in the two radiator areas for a fighter but at 400yds gives puts all the bullets on a bomber engine in a more vertical grouping

I am still not sure. The 200yd grouping is a bit too wide but on the other hand at those ranges you are often shooting at a dodging target anyway.

7855

ATAG_EvangelusE
Mar-03-2014, 07:51
The only thing I notice is that if you set all eight guns on a Spit to 200 yds for both H and V, the pattern displayed (wingtip to wingtip) in the calculator is perfectly flat.

I wondered if this was correct given that the outer guns are slightly higher compared to the inner guns?

(I expected to see the pattern of a default convergence setting match the Spits wing profile but I could be wrong)

I entered my current settings, (which have different V and H for all guns) into the calculator and it revealed some problems with them, in fact, looking at my own personal guncam vids I could see thet the most effective setting for me was a bog standard 180yd for both V and H. I seem to be getting better results now ....so thanks, very useful!

DeXaÏ_☨
Mar-03-2014, 15:08
Not a complaint, just clarifying how it is supposed to work, but is the 'Reverse Calculator' designed to only calculate hits *after* convergence?

No worries ;) You can and should "complain" to get this calculator debugged and improved ;)

It's supposed to work for all "allowable" convergence (100 to 1000m in the game).


I tried to calculate what convergence would pass through the radiator regions at 200yds and converge further on and it insisted on making it converge between me and the target then hitting the rads after. In the end I just did it by trial and error.

I implemented a poka yoke so it'll turn red and indicate "NC" (non converging) if your H convergence is out of this range (100-1000m).
For example, you cannot have guns pointing away from your centerline (negative convergence), or parallel to (infinite H Conv) as you couldn't implement them in the game.
With the setup you indicates, it seems to work on my version.

If you're within those tolerances and it still doesn't work, could you please post the exact "Horizontal Location (yd) [X]", distance (yd) [Z] and the gun ID ? I'd check it on my version.

Thanks !

Cheers !

DeXaÏ_☨
Mar-03-2014, 16:24
The only thing I notice is that if you set all eight guns on a Spit to 200 yds for both H and V, the pattern displayed (wingtip to wingtip) in the calculator is perfectly flat.

I wondered if this was correct given that the outer guns are slightly higher compared to the inner guns?

Very good remark ! You're right, their Y for Z=0 shouldn't be at the same level.
My calculator considers all guns are aligned to an elevation (Y) of -1.16yd below gunsight (0;0;0) in [X;Y;Z], which corresponds to G2/3 and G5/6 Y location. Nonetheless, G1/8 are located -1.05yd below and G4/5 -1.25yd on the Y axis (or around that).

The main reason this is not implemented is : I got lazy, hum, let me reformulate : I considered +0.11/-0.9yd variation in the Y location was an acceptable tolerance considering the quality of the blueprint I extracted those data from and mostly, the fact I should re-extract all the data from the JBM calculator for G1/8 and G4/5 (the most boring part, C&P bonanza :) ).

I planed to include that in the limitations list, but eventually forgot... Thanks for reminding me !
issue solved from version F2.0 and on


(I expected to see the pattern of a default convergence setting match the Spits wing profile but I could be wrong)
Well, here, I kinda disagree/depends on how the games calculate that: my hypothesis (how it was done in real life) is that the guns are converging toward the point the gunsight is aiming at (with an offset in real life). The guns are not set to converge to their own "Y location". (I'm not sure this sentence makes any sense ;) )
Let's get a bit technical : the point of reference is the gunsight, (0;0;0) in (X;Y;Z) in yd, * = not relevant for our problem.
(X=left wingtip to right wingtip, Y= rad to canopy, vertical , Z = tail to nose)
G1 is located at (*;-1.05;~0), if you set its convergence to 200yd (183m), it means it'll cross your line of sight at (*;0;200), but not (*;-1.05;200).

But that's a good point, which I'm not to sure of. To confirm that, I'll try to set a 100m convergence on G4/5 with tracers, and see if the bullets trajectory is almost flat (convergence set for "gun location") or climbs a lot (my hypothesis/real life).
issue solved from version F2.0 and on


I entered my current settings, (which have different V and H for all guns) into the calculator and it revealed some problems with them, in fact, looking at my own personal guncam vids I could see thet the most effective setting for me was a bog standard 180yd for both V and H. I seem to be getting better results now ....so thanks, very useful!

Great ! I'm glad it helped. It might be a coincidence, but my kill ratio increased from 0.5 to 0.75 since I'm working on the calculator (I see Excel equations when I pull the trigger ;)

Roblex
Mar-04-2014, 13:57
Could you tell me where the 109 profile is held? I can't find it. I wanted to add a faint bomber profile on top of the 109 profile so I could see where the bullets are hitting when I shoot at a bomber that is beyond my convergence range. Perhaps if I colour coded them I could get the three main bombers on there. You might want to consider adding tick boxes so people can swap the profiles in and out for different targets.

DeXaÏ_☨
Mar-04-2014, 14:00
/!\ USE LATEST VERSION /!\

My boundary conditions are incorrect : I tested it after ATAG_EvangelusE remarks and it shows convergence are set per gun alignment. The bad news is that I need to rework the V convergence. The good one is that it'll simplify the calculation a lot and that I can now be even more accurate (Y location of the guns is not a problem anymore).

For medium V convergence (200 to 700m), the variation seems not to be very important between Game Vs Calculator, but it in the extreme values, there is a big difference. Moreover, probably no need to aim slightly under the target.

Please forget all what I said about V conv in the previous posts. I'll edit previous post with a disclaimer to avoid confusion.

I'm very sorry about that, I should have checked.
I hope to get that corrected, debugged and released by tomorrow evening.

Reverse calculator and X=f(Z) are still valid.

@ Roblex : Gunsight horizontal bars + circle are scaled function of distance and it seem to work nicely. It'll get it released after I debug the V Conv.

/!\ USE LATEST VERSION /!\

DeXaÏ_☨
Mar-05-2014, 14:51
Could you tell me where the 109 profile is held? I can't find it. I wanted to add a faint bomber profile on top of the 109 profile so I could see where the bullets are hitting when I shoot at a bomber that is beyond my convergence range. Perhaps if I colour coded them I could get the three main bombers on there. You might want to consider adding tick boxes so people can swap the profiles in and out for different targets.

Hi Roblex,

Bf109 image is actually the "Zero" point texture/image. I rescaled it manually with Gimp because Excel display its size as per the resolution of the image (and that's why there's a warning not to rescale/resize the "view on target charts"/C# charts).

To rescale the Bf109 image function of distance or to add other target to scale, I would need to use VBA code, which I do not master... yet (or resize each target image to scale...)

So I'm sorry, this is a good idea, but I cannot implement it for the moment. A workaround would be to consider that a Bf109 cell is approximately the size of a bomber engine.

I can't remember what image was the final one, but it's probably one of those : 7913 7914 7912

By the way, did you manage to solve your issue with the non converging trajectory ?

Cheers !

DeXaÏ_☨
Mar-05-2014, 15:51
Hello everyone !

Please find the latest version of the calculator below.

This version is updated with:
- V Convergence [Y] correction so that it fits game model as per discussion wiht ATAG_EvangelusE
- Vertical gun location [Y] implemented
- Gunsight "base" bars are scaled to represent perspective as per Roblex idea
- Gunsight "circle" is scaled as well to help appreciate the distance from target
- Poka Yoke abundance to restrain the H and V convergence to the ones possible in the game (100-1000m)
- Correction of the vertical model (in the video, V Conv is unstable with 900-1000m setup... that was due to a m/yd conversion problem, solved)
- V and H convergence menus inverted to fit game menus
- Intersects correction so that "non game-supported" convergence will not show intersect points
- Possibility to enter 0 or nothing or "non game-supported" convergence in H or V conv to disable curves
- Debug and small scale improvements

F2.0 version here : http://goo.gl/6ApWnZ

I tend to understand why the game developers used the gun convergence over gunsight convergence method : it's much simpler to work with and to export. For instance, with little modification, I can now generate the same calculator for hurricanes, all I need is boundary conditions = a blueprint :) to be continued...

Roblex
Mar-06-2014, 03:12
Are you sure the new version is right? If I set all H & V convergence to 183 (ie 200yds) then the new spreadsheet tells me that at 200yds all my bullets will pass about 3 feet beneath my aim point. In the screenshot below the gunsight is set to 32ft, 200yds, 0.5 v offset MOA 4

To get the bullets on target you have to set the outer guns to 650m V-Conv and the inner guns to 750m V-Conv


http://i56.servimg.com/u/f56/18/40/46/21/conv2110.jpg

DeXaÏ_☨
Mar-06-2014, 17:24
Are you sure the new version is right? If I set all H & V convergence to 183 (ie 200yds) then the new spreadsheet tells me that at 200yds all my bullets will pass about 3 feet beneath my aim point. In the screenshot below the gunsight is set to 32ft, 200yds, 0.5 v offset MOA 4

To get the bullets on target you have to set the outer guns to 650m V-Conv and the inner guns to 750m V-Conv

Hi Roblex,

I'm not sure yet :)

I ran some tests yesterday and today, but due to the very large spread of the bullets, it is inconclusive for the moment.

I'll have more time tomorrow and during the weekend to validate or invalidate.

Nevertheless, as you can see on below pictures, with F1.0 or F2.0, the bullets trajectories are quite similar:
7952
7953
7954
7955
7956

So no alarm.

I got a bit carried away as the potential mistake I probably made was quite "stupid" (1st rule = Check your boundary conditions), but the consequences are contained ;)

Cheers !

Roblex
Mar-07-2014, 07:09
Ok. Your own custom spread pattern stays much the same but I am curious what you, or any others, are seeing on the new spreadsheet when you set everything for a point convergence at 200yds (183 metres) both Horizontal and Vertical. If other people are getting all the bullets in one spot exactly where it is aimed then maybe I have a problem with my own version. It works on the previous version.

ATAG_EvangelusE
Mar-07-2014, 10:27
Hi Dex, first - many thanks for the work you are doing.

Anway, despite being crude hope this helps, from my own tests (see video), at convergence where both H and V are set to 200 - the guns appear to be aligned to the centre point of the gunsight. As Roblex points out, on the spread sheet the guns appear to be converging below the target.



http://youtu.be/O3ElufPYdGg

DeXaÏ_☨
Mar-07-2014, 11:58
Ok. Your own custom spread pattern stays much the same but I am curious what you, or any others, are seeing on the new spreadsheet when you set everything for a point convergence at 200yds (183 metres) both Horizontal and Vertical. If other people are getting all the bullets in one spot exactly where it is aimed then maybe I have a problem with my own version. It works on the previous version.

Hi Roblex,

The Excel and your settings should be fine, the difference is coming from the fact I changed the equations in the calculator. This is why, with V<F2.0, your shots are fine, but with V≥F2.0 they're ~1.16yd under the target.

The problem is how the game is defining V convergence (H seems to be quite fine), for the calculators I made:
A- My first hypothesis, the "historical one", is that the bullets converge with the gunsight (Calculators <F2.0)
B- The second hypothesis, is that the bullets converge with the Y location of each gun (Calculators ≥F2.0).

I'm currently running tests to see which one is better matching. But the 4 problems I have so far in validating/invalidating are:
1- The spread of the bullets is important, so I got hard time defining a trajectory
2- When I test, the plane axis is not horizontal, which supposedly modifies the results (acceptable)
3- Setting the convergence is a pain ;)
4- I got no scale on my gunsight, so I got to work in qualitative/proportions

So I'm on it, but it's taking some time !

Cheers !

DeXaÏ_☨
Mar-07-2014, 12:52
Hi Dex, first - many thanks for the work you are doing.

Anway, despite being crude hope this helps, from my own tests (see video), at convergence where both H and V are set to 200 - the guns appear to be aligned to the centre point of the gunsight. As Roblex points out, on the spread sheet the guns appear to be converging below the target.


Hi EvangelusE !

This is very nice video and information, thank you very much !

I didn't know it was possible to set targets like that in the QMB.

Can you confirm the distance from target is 200yd ?

200 yd would mean the target is 3.48yd in width, 1.92yd in height for the top part, and 3.22yd in total height (feet included).

Your aim is slightly below the center part of the target, let's say 0.48yd from the bottom part of the panel and yet it seems the impact locations are (mostly?) on the board.

The F2.0 calculator indicates most of the shots would go 1.1yd below your line of sight, so it seems V<F2.0 seems to closer than F2.0 to the game model.

Nonetheless, we also see that due to shot inaccuracy, one shot hits the top right corner of the board (supposedly 1.44yd above the line of sight at 200yd... which makes 25 MOA variation... I think slingshots or this one (https://www.youtube.com/watch?v=kMB3gG-5tkU) have better accuracy ;).

I'll use your QMB idea and make more tests this weekend end.

Thank you very much for the feedback !

PS: As a remark, red tracers (dimmed and not dimmed) use cordite powder, and are not considered in this calculator. But at that distance, I don't think it'd be a problem anyway.

Roblex
Mar-07-2014, 12:55
Thanks DeXal. Everyone appreciates what you are trying to do, I only told you so you realised there was a problem. Nobody is nagging you to get it fixed. We in the online air combat world are used to waiting so just do it for yourself when you feel like doing it and if that means 'never' then that is the way it is :-)

ATAG_EvangelusE
Mar-07-2014, 13:50
As Roblex says, - you are doing a great job and we appreciate what you are doing.

The QMB file I set up is an old one to test the accuracy of the gunsight adjustments rather than convergence. In the video you can see a bomber, using its wingspan as a reference, its distance could be roughly determined by adjusting the gunsight untill the crosshairs matched the wingtip to wingtip distance. In normal cockpit view you cannot see the bomber but in 'wonder woman' view the bomber is clearly visible with the gunsight ring above it. I doubt that such a set up is entirely accurate enough for what you are trying to do.

Anyway, best of luck and appreciate your hard work.

Catseye
Mar-09-2014, 13:08
Hi EvangelusE !


Your aim is slightly below the center part of the target, let's say 0.48yd from the bottom part of the panel and yet it seems the impact locations are (mostly?) on the board.

The F2.0 calculator indicates most of the shots would go 1.1yd below your line of sight, so it seems V<F2.0 seems to closer than F2.0 to the game model.



Interesting numbers.

Almost the difference between the height of the gunsight above the gun platform.

I don't know if COD calculates that condition or just points the gunsight straight out not compensating for height. If it doesn't compensate, the bullets will fall below the sight line.

I've built in a 40" height difference when I was calculating.

Cheers,
Cats . . .

9./JG52 Mindle
Mar-10-2014, 06:04
In practice over last week or so..

183 / 183 seems to lift the bullet stream a little better than 183 / 400 in a turning fight. Fits with general trajectory prediction of spreadsheet that the bullets at v183m will cross LOS on the 'up' earlier than they will at v400m and then fly further before dropping back on LOS.

Both pretty much along LOS when viewed through gunsight flying straight and level, perhaps 183/183 slightly more on the pipper.

But recoil vibration and my (not so) steady hand will probably negate any differences.

Good work. Keep going. :thumbsup::thumbsup:

9./JG52 Mindle
Mar-10-2014, 06:15
Pity there isn't a 'firing range' where flyers could set convergences on a target instead of shooting the sides of hangars. :)

ATAG_Bliss
Mar-10-2014, 13:09
Pity there isn't a 'firing range' where flyers could set convergences on a target instead of shooting the sides of hangars. :)

If you look in the FMB there is a gun firing board (can't remember the proper term for it) but it's a target that you place on the ground and fire at. Don't know how accurate it is or even if it tells you anything about your convergence, but there is an object there to try it out designed for that purpose :thumbsup:

9./JG52 Mindle
Mar-10-2014, 13:52
cheers, will look. :thumbsup:

DeXaÏ_☨
Mar-10-2014, 18:30
Hi Guys,

Thank you all for the feedback, much appreciated.

I got seduced by online gaming rather than the QMB this weekend :) so I'll need a bit more time.
Let's say I was practicing the convergence rather than working on the theory ;)


Thanks DeXal. Everyone appreciates what you are trying to do, I only told you so you realised there was a problem. Nobody is nagging you to get it fixed. We in the online air combat world are used to waiting so just do it for yourself when you feel like doing it and if that means 'never' then that is the way it is :-)

Hey Roblex !

No problem at all ! I think it's a nice challenge and I enjoy trying to help the community with my ballistics and Excel skills (which, in general, doesn't sound much like fun ;).

The hardest part has been done, so it's only a matter of keeping the workflow steady from now on. Moreover, once I confirm which axis the bullets are converging with, I'll be able to export the methodology to other aircraft reasonably easily (mostly C&P).


The QMB file I set up is an old one to test the accuracy of the gunsight adjustments rather than convergence. In the video you can see a bomber, using its wingspan as a reference, its distance could be roughly determined by adjusting the gunsight untill the crosshairs matched the wingtip to wingtip distance. In normal cockpit view you cannot see the bomber but in 'wonder woman' view the bomber is clearly visible with the gunsight ring above it. I doubt that such a set up is entirely accurate enough for what you are trying to do.

Hey EvangelusE,

Ok, noted.

I'll use the plane as a scale in the QMB, that's a good idea. Just need to get more familiar with the interface :)

Well, the distance (Z) accuracy is ok, the Y location is giving me a hard time though ;)


Almost the difference between the height of the gunsight above the gun platform.
I don't know if COD calculates that condition or just points the gunsight straight out not compensating for height. If it doesn't compensate, the bullets will fall below the sight line. I've built in a 40" height difference when I was calculating.

Hi Cats,

As per my blueprint, the guns location, considering gunsight is (X;Y)=(0;0) are the following (in yd):
G1: (-4,16;-1,03)
G2: (-3,18;-1,16)
G3: (-2,97;-1,19)
G4: (-2,29;-1,27)
X becomes positive for G5,6,7&8.

My guess/hypothesis is that the reflex gunsight is pointing "straight" : aligned with the plane axis. That ensures you go where you aim and I haven't noticed "slip/slide" of my plane Vs the bomber engine I was aiming at for example.
But that's an interesting remark : I do not know how aligning the gunsight with the plane axis was performed in real life (for possible "pre-answer", see boresight (http://upload.wikimedia.org/wikipedia/commons/7/77/Bundesarchiv_Bild_101I-390-1220-20%2C_Russland%2C_Flugzeug_Me_109_des_JG_54%2C_War tung.jpg)).

About the V Conv, I cannot be 100% positive, but it seems the guns are converging toward (a) line(s) that is located above their own Y position.
For example, G4/5 with 100m V conv seems to go above gunsight, G4/5 with 300-400m seems not to go above gunsight. If it was converging per gun position, the trend would be inverted (the shorter the lower).
Nonetheless, if it was strictly converging with the gunsight, with 300-400m they would be on the LOS, and I see them under... (hypothesis : the guns are converging with the axis going through the nose of the plane, or the 0;0;0 reference of the plane model. I plan on checking the former as well, got no info on the later).

What I'm trying to check right now are "singularities", to see which model is correct:
If G2/3/6/7 are converging per gunsight, bullets will have same trajectory if I set them at 100m or 940m (see V<F2.0)
If guns are converging per their Y location, with 100m V Conv, none will go above gunsight.
...


In practice over last week or so..
183 / 183 seems to lift the bullet stream a little better than 183 / 400 in a turning fight. Fits with general trajectory prediction of spreadsheet that the bullets at v183m will cross LOS on the 'up' earlier than they will at v400m and then fly further before dropping back on LOS.
Both pretty much along LOS when viewed through gunsight flying straight and level, perhaps 183/183 slightly more on the pipper.
But recoil vibration and my (not so) steady hand will probably negate any differences.

Hey Mindle,

I tend to agree with you. With LOS convergence hypothesis (V<F2.0) according to my calculation, the lowest elevation will be achieved by using ~350m in V Conv. It seems to concur with your observations.

And yeah, I think the bullet spread is a bit too wide (Guns/ammo are ~4 MOA, mounts and wings vibrations will add to that but not multiply it, this chart (http://upload.wikimedia.org/wikipedia/commons/d/d7/P-47_gun_harmonization_-_two_types.jpg) shows a maximum outer limit of 4 MILS, hence 13.75MOA (2yd spread @ 500yd distance) and we're talking 50Cal (12.7x99mm, smaller ammo, smaller spread if projectile and barrel quality are equivalent IMO) and for similar caliber (Nazi Germany, NG), this picture (http://www.pumaszallas.hu/Private/VO101_Tom/bugtracker/f195_shooting_range_3.jpg) gives also an order of magnitude (Luftwaffe SOP for calibration was recommended at 100m, but procedure included as well 50, 100, 150, 200 and 400m, the target circles are around 15-20cm in diameter, 6-8 in).

Cheers !

Roblex
Mar-11-2014, 04:09
It looks like the RAF used geometry as well as trial & error to set the convergence i.e. 'If the rounds pass through these points at 200yds then they will all meet at 250 yds. In the picture below I am not sure why the cannon targets are offset from each other though; were they not mounted in the wings equally?

http://ww2today.com/wp-content/uploads/2013/04/Spitfire-gun-harmonisation-595x403.jpg

Gun harmonisation board at Biggin Hill, Kent, set up for a Supermarine Spitfire Mark IXB of No. 341 (Free French) Squadron RAF, which has been jacked up into a level flying position in the Blister Hangar fifty yards beyond by armourers of No. 3101 Servicing Echelon. The discs on the board have placed in order to harmonise the guns so that their lines of fire converge on a point 250 yards from the aircraft. The four small outside discs are the harmonising points for the four .303 Browning machine guns, while the larger discs inboard of these are for the two 20mm cannon. The upper centre spot is for the pilot’s reflector sight, and the lower spot to the left of centre is for the camera gun.

Also this for the P51

http://i888.photobucket.com/albums/ac88/Corsican_Corsair/P51-2.jpg

This diagram may also help confirm how vertical convergence was arranged to pass through the gunsight.

http://i888.photobucket.com/albums/ac88/Corsican_Corsair/P47-2.jpg

Archie
Mar-11-2014, 04:48
Thanks for posting that Roblex, very interesting picture! :thumbsup:

92 Sqn. Philstyle (QJ-P)
Mar-11-2014, 04:52
If you look in the FMB there is a gun firing board (can't remember the proper term for it) but it's a target that you place on the ground and fire at. Don't know how accurate it is or even if it tells you anything about your convergence, but there is an object there to try it out designed for that purpose :thumbsup:

The firing board cannot be used without an aircraft lifter (the AoA of a tail-dragger on the ground just fires the rounds into the sky).
The lifters in the FMB do not allow aircraft to be placed on top of them. They just blow up, or snap. I've tried.

:(

Roblex
Mar-11-2014, 07:46
Yes but you can magically suspend the board in the air :D

1lokos
Mar-11-2014, 13:57
If you look in the FMB there is a gun firing board (can't remember the proper term for it)

Static > Airfield > Airfield Boresight Board for Spitfire (also available a Bf 109 one).

http://i57.tinypic.com/2qjeg3r.jpg

But:


The firing board cannot be used without an aircraft lifter (the AoA of a tail-dragger on the ground just fires the rounds into the sky).
The lifters in the FMB do not allow aircraft to be placed on top of them. They just blow up, or snap. I've tried.:(

1 - A "smart" one may think in play with boresight Z offset (height) - a very difficult task that involve many trial and error, if successful need:

2 - Place the boresight on convergence distance (more trial and error) ... Ops. Not necessarily convergence, but the distance that guns match the pattern on boresight (that means ??? ).

3 - If, after all this work you hit the boresight, they are "shoot down" , like a balloon hit by gunfire (probable share the same "FM"). :-P

http://i60.tinypic.com/vrvrds.jpg

And that's not all, since MG's don't fire at same time, a fire burst that lasts more than 0,2 second move the plane nose for left, and for right at the end of ammunition...

Tha's why these guys sit on Bf 109 wings.

http://i57.tinypic.com/2dax10g.jpg

Yes, I try this. :doh: :cry: :D

"Bore... thing"

Sokol1

DeXaÏ_☨
Mar-15-2014, 12:42
Hi Guys,

I took some time to train with the FMB. Thanks Phil Enz of the 92 Squadron for the youtube tutorial videos.

I found a nice location for the convergence test (Willington or something like that) : It's close to some hills on top of which I place my targets (to counteract the gunsight/ground angle when the tail wheel is on the ground).
I used the FW200 as a scale to set the distance (33m wingspan, 3 planes = 100m)
I use a raw of Westminster abbey(s) as my target : it's flat and it's the tallest building in the FMB (? any input for taller building welcome) plus it cannot be destroyed with guns.
I load the gun I want to control with the De Wilde (sparkles on impact, visible even at 1000m distance).
So I have the methodology for live test.

Now, the bad news : my file got corrupted (some problem with a road I think) and I cannot load it anymore...

I'll do it again, but a bit later (to keep what's left of my sanity).

Beside, after "playing" with the FMB, this stuff is so damn frustrating and counter intuitive that I want to thank all the guys who worked (probably very hard) on the online missions and that I now realize how hard and how much work it should have been :)

For info, I posted another version of the calculator, it has all the latest update but uses the LOS V convergence equations (Which seems to be closer to the game model, even though not matching exactly).

9./JG52 Mindle
Apr-14-2014, 09:19
9037

In the future it seems the problem of horizontal convergence is still not solved...

The same goes for shoulder shooting!


9038

Those nose guns still great for PK's though...


Sorry, couldn't resist! :D

DeXaÏ_☨
Apr-15-2014, 16:32
Hi guys,

Please find below the link to the last version of the calculator.

I tried to test the V convergence in the game, to see how CLOD is handling them, but it was not conclusive: The data to be measured are much smaller than the variations. Besides, it is quite long (and a pain) to test (FMB, convergence setups, loadout...).

So I made the hypothesis the game handles the convergences as they were handled in real life (which seems to reasonably match as per my tests, even though I'm not yet completely sure): the bullets trajectories are converging with the gunsight (LoS).

This new version [F2.3 LoS] includes:
- Each guns V conv and subsequent Y location of the bullets are calculated independently.
- Bullets ToS (Time of flight) appearing in each Cx "view on target" chart.
- Velocity (m/s) appearing in each Cx "view on target" chart.

So I guess this is the final version. I do not plan to update it anymore, except for some debug if any.

I haven't been flying lately because I believe I uploaded a corrupted BIOS during an update. The MOBO is not responding (no POST, no BIOS) and is going through RMA at the moment.
I should be back online in 3-5 weeks with a new graphic card, more RAM, a new SSD and a backup harddisc (murphy law: I updated the BIOS before saving my data ;) but it should be fine).

Good Hunting !

[F2.3 LoS]: http://goo.gl/jexGQi

9./JG52 Mindle
Apr-16-2014, 04:08
Thanks :thumbsup:

DeXaÏ_☨
May-11-2014, 06:50
Hi Guys,

After testing the calculator during gameplay, I think it's working quite well.

My air kill ratio increased from 0.6 to 0.8 and I haven't changed my tactics recently, nor my ammo load-out (but played more though).

I tried the following, and they seem to be working very well for me:
H Conv first line, V Conv, second line
G1 to 8 from left to right
"1" : bullets horizontal trajectory parallel (More spread in the X axis, versatility in engagement distance, accuracy less critical)
"2" : bullets horizontal trajectory intersecting (More focus in the X axis, very efficient within 120-260 yd, accuracy needed)
"A" : bullets vertical trajectory parallel (More spread in the Y axis, versatility in engagement distance, accuracy less critical)
"B" : bullets vertical trajectory intersecting (More focus in the Y axis, very efficient within 60-260 yd, accuracy needed)

A1
218 189 166 140 140 166 189 218
565 525 470 350 430 500 545 590
A2
172 170 184 188 188 184 170 172
565 525 470 350 430 500 545 590
B1
218 189 166 140 140 166 189 218
345 440 510 570 600 540 475 400
B2
172 170 184 188 188 184 170 172
345 440 510 570 600 540 475 400

I tend to favor the A1 or B1, as I prefer having quite spread lethality envelope, yet less dense (once you got few hits, the drag penalty makes the final blow easier, and/or prevents fight back).

I set my gunsight to 350yd and 32ft: it is the maximum engagement distance for those Conv Setup ("1") and at 350yd, bullets from one wing will hit right in between the center dot of the gunsight and the lateral bar (but due to the bullet ToF, I rarely use that I must admit, except for 110 and bombers).

Also, even though the calculator is not supposed to be compatible with Cordite rounds, I found using those quite handy : Due to their slower initial velocity, during a deflection shot, Nitrocellulose and Cordite trajectories will spread, increasing the "showering". Yet, the difference will be too small to be a penalty for straight shots and/or distance of engagement <200yd.

Good Hunting !

Yblad
May-29-2014, 21:03
I tend to agree that there isn't really a right way to do convergence. There are clearly going to be pros and cons no matter what system you use. That said, I nevertheless think it's a mistake to underestimate the importance of the vertical plane and to, for theoretical reasons, attempt to stretch your convergence out based solely on a set of horizontal projections.


You're right. Adding in the vertical dimension does matter.
I have a preference for that too, which is based on

slightly further out vertical convergence for the weapons which horizontally converge close in, and
slightly closer in convergence for the weapons which horizontally convergence further out.




I'm afraid that this is incorrect. The horizontal and vertical components of the movement are entirely mathematically seperate. You can fire up at 45 degress or at 0 degress and the convergence horizontally will be identicle. It's pretty much rule one of balistics. It's a little hard to picture at wierd angles and deflection shooting but trust me (I'm a professional theoretical physicist) when I say that these convergences charts work regardless of the vertical happenings. Even if you are rotated 90 degrees so you are wings down the convergences are identical, just all shifted in an arch towards the ground. At the point of impact it's identical. They just all shift down at the same time in the same way. Well, unless you want to consider the micro-gravitational changes due to one bullet being at a slightly higher altidude than the other.

EDIT: This is of course the simplified way of looking at it, which I didn't make clear when I posted. If you read down the next couple of posts you will see an interesting debate on the more complex actual events, and to what degree those events are worth considering. I was a little over enthusiastic in my wording here which made things unclear. Also apologies to 92 sqn phil, who I misunderstood in his intent for what he said in the post I quoted.

92 Sqn. Philstyle (QJ-P)
May-30-2014, 04:18
The horizontal and vertical components of the movement are entirely mathematically seperate. You can fire up at 45 degress or at 0 degress and the convergence horizontally will be identicle. It's pretty much rule one of balistics.

I think you'll find that you agree with us. Of course they are "separate" from each other. Which is why I use an independent setting for each.

For horizontal convergence, I use the point where the bullets cross each-other in the horizontal plane.
In the vertical plane, the bullets never cross each other, they cross the angle-of-attack of the aircraft doing the firing. This is quite another matter, and has rto be thought about differently from the horizontal activities of the stream of bullets.

Unless we're talking about different things entirely...

DeXaÏ_☨
Jun-02-2014, 07:49
I'm afraid that this is incorrect. The horizontal and vertical components of the movement are entirely mathematically seperate.
Depends of your Frame of Reference [FoR] : if the plane is in [FoRp] Xp (right wing tip to left win tip),Yp (along the rudder, down to up), Zp (tail to nose) centered on the gunsight, and the ground referential is in [FoRg] Xg,Yg,Zg (gravity applying along Y) depending on your plane orientation, gravity will be applied differently along Xp,Yp and Zp function of the angle between those 2 FoR. Gravity components are mathematically separated in [FoRg] (because gravity defines FoRg) but not in [FoRp].


You can fire up at 45 degress or at 0 degress and the convergence horizontally will be identicle. It's pretty much rule one of balistics.
No, if you change the angle between Yp and Yg, gravity, hence bullet drop will not have the same orientation, and thus the convergence will be modified. I agree that at short distance of engagement, it will not make a noticeable difference, but it would at 1000yd (bullet drop ~5 yards down Yp) and even more at 2000yd (Zp) (bullet drop ~40 yards down Yp).


It's a little hard to picture at wierd angles and deflection shooting but trust me (I'm a professional theoretical physicist) when I say that these convergences charts work regardless of the vertical happenings.
They won't, it's in the disclaimer, even though they'll be good enough for most purpose.
Moreover, if you include deflection, you then have other accelerations equations to include in your calculation and you start working in dynamic (good luck ;) )
For example, if you have very long V convergences, and follow a target in a dive, the gravity will not apply on the Yp axis, and all your bullets will tend to go up along Yp, for H conv, the bullets will be pulled by gravity, so they will tend to intersect further out. According to my calculations and my setup, I'll start missing a diving target (Yg=Yp) if he's >300yd out in front of me and I keep my gunsight centered on him (I need to manually correct and aim under its belly if our wings are parallel, that's coming from V conv).


Even if you are rotated 90 degrees so you are wings down the convergences are identical, just all shifted in an arch towards the ground. At the point of impact it's identical.
You will turn linear equations into parabolic ones, they're not gonna intercept at the same point.
If you consider a gun with a scope 42 inches above the barrel, and you set that gun to convergence at 400yd (gun set in normal conditions : barrel and sight aligned on Yg), it is not gonna work if you keep the same setup and try to shoot at the same target but with your gun laying on the side (rotation by -90 degrees): Bullet will drop under the target (Yg) and deviate left (Xg). Because the bullet drop compensation will not apply along Yg anymore.


They just all shift down at the same time in the same way. Well, unless you want to consider the micro-gravitational changes due to one bullet being at a slightly higher altidude than the other
They all shift down at the same time, but their initial angles not being the same in the FoRg, it will modify their trajectories differently.
They would if all the guns trajectories would be set parallel to each other (infinite H convergence), which is not possible in the game (one wing can have its guns set parallel, it can be done through the reverse calculator)


In the vertical plane, the bullets never cross each other, they cross the angle-of-attack of the aircraft doing the firing
Hey Phil ! They can cross each others trajectories if you set the lower gun (G4/5) to V converge the longest and highest guns (G1/8) the shortest, but as per my tests, it's not very useful, at least for me (B type in my previous post). See here:
9918
9919

Cheers !

ATAG_Snapper
Jun-02-2014, 08:54
Thanks, Dex -- will give these settings a try! :salute:


Hi Guys,

After testing the calculator during gameplay, I think it's working quite well.

My air kill ratio increased from 0.6 to 0.8 and I haven't changed my tactics recently, nor my ammo load-out (but played more though).

I tried the following, and they seem to be working very well for me:
H Conv first line, V Conv, second line
G1 to 8 from left to right
"1" : bullets horizontal trajectory parallel (More spread in the X axis, versatility in engagement distance, accuracy less critical)
"2" : bullets horizontal trajectory intersecting (More focus in the X axis, very efficient within 120-260 yd, accuracy needed)
"A" : bullets vertical trajectory parallel (More spread in the Y axis, versatility in engagement distance, accuracy less critical)
"B" : bullets vertical trajectory intersecting (More focus in the Y axis, very efficient within 60-260 yd, accuracy needed)

A1
218 189 166 140 140 166 189 218
565 525 470 350 430 500 545 590
A2
172 170 184 188 188 184 170 172
565 525 470 350 430 500 545 590
B1
218 189 166 140 140 166 189 218
345 440 510 570 600 540 475 400
B2
172 170 184 188 188 184 170 172
345 440 510 570 600 540 475 400

I tend to favor the A1 or B1, as I prefer having quite spread lethality envelope, yet less dense (once you got few hits, the drag penalty makes the final blow easier, and/or prevents fight back).

I set my gunsight to 350yd and 32ft: it is the maximum engagement distance for those Conv Setup ("1") and at 350yd, bullets from one wing will hit right in between the center dot of the gunsight and the lateral bar (but due to the bullet ToF, I rarely use that I must admit, except for 110 and bombers).

Also, even though the calculator is not supposed to be compatible with Cordite rounds, I found using those quite handy : Due to their slower initial velocity, during a deflection shot, Nitrocellulose and Cordite trajectories will spread, increasing the "showering". Yet, the difference will be too small to be a penalty for straight shots and/or distance of engagement <200yd.

Good Hunting !

DeXaÏ_☨
Jun-02-2014, 19:27
Thanks, Dex -- will give these settings a try! :salute:

Hey Snapper !

Great, hope you'll like them !

I might modify the Convs I'm using (A1), to make them spread even more at closer range, to see what it gives.
I'll give a feedback later after testing.

I also managed few times to use the "target in between the bar and dot" of the gunsight technique (see pic below), on runaway 109s. No important damage, but few hits or close enough (I use tracers) to make them initiate evasive maneuvers and then catch up on them. So it seems it's a viable technique.

Cheers !

9932

ATAG_Snapper
Jun-02-2014, 21:06
Thanks, Dex. I've tried the A1 spread in a few sorties in a Spitfire 1a 100 octane with some success , so I'll stick with A1 for a bit to wring it out a bit. :D I got shared kills for one Ju88 and three 109's in three sorties which is good for my limited abilities. It's hard to find the right load and convergences for armoured bombers and light fighters.

92 Sqn. Philstyle (QJ-P)
Jun-03-2014, 05:33
Hey Phil ! They can cross each others trajectories if you set the lower gun (G4/5) to V converge the longest and highest guns (G1/8) the shortest, but as per my tests, it's not very useful, at least for me (B type in my previous post). See here:
9918
9919

Cheers !

ah, yes! of course. ;)

Catseye
Jun-03-2014, 16:58
Thanks, Dex. I've tried the A1 spread in a few sorties in a Spitfire 1a 100 octane with some success , so I'll stick with A1 for a bit to wring it out a bit. :D I got shared kills for one Ju88 and three 109's in three sorties which is good for my limited abilities. It's hard to find the right load and convergences for armoured bombers and light fighters.

Hi Snapper,
The B2 worked a charm for me and now I'm trying out Dex's latest .xml chart setup and not sure yet whether to go back to B2 or stay with the chart.
Both work fine. I get quicker kills at distance with the chart and better kills at lethal mid-short distance with B2. Nice to see the spread out along the wings but having worked on the ballistics/damage model in COD, I'm still considering the need for point convergence vs. multiple single bullet stream contact with respect that the damage model is still variable and will be further worked on for TF5.0.

My observation at this time is that it is not necessary to have all bullets converge at the same point but rather have more of a broader spread increasing the options of hitting a vital component. (For now at this stage of COD TF development)

Cheers,
Cats . . .

ATAG_Snapper
Jun-03-2014, 19:16
Rgr Cats. Good input. Always fun to try stuff like this out. :thumbsup:

:)

Yblad
Jun-04-2014, 01:32
I think you'll find that you agree with us. Of course they are "separate" from each other. Which is why I use an independent setting for each.

For horizontal convergence, I use the point where the bullets cross each-other in the horizontal plane.
In the vertical plane, the bullets never cross each other, they cross the angle-of-attack of the aircraft doing the firing. This is quite another matter, and has rto be thought about differently from the horizontal activities of the stream of bullets.

Unless we're talking about different things entirely...

My apologies, I misread what you were saying as saying that the verticle convergences need to be taken into account when looking at the horizontal paths rather than saying that the verticals also need to be considered seperately. Entirely my error


Depends of your Frame of Reference [FoR] : if the plane is in [FoRp] Xp (right wing tip to left win tip),Yp (along the rudder, down to up), Zp (tail to nose) centered on the gunsight, and the ground referential is in [FoRg] Xg,Yg,Zg (gravity applying along Y) depending on your plane orientation, gravity will be applied differently along Xp,Yp and Zp function of the angle between those 2 FoR. Gravity components are mathematically separated in [FoRg] (because gravity defines FoRg) but not in [FoRp]....




I agree entirely. I was trying to put things simply without wittering on for ages about complicated details which ultimately at the ranges in question make virtually no difference. In the rotated state I agree in that the lines of fire will suffer some spreading from the parabolas. However the effect, unless you are setting guns at extremely different settings to each other, is far too small to worry about at any range within the convergences suggested. You would have to either have very different settings to make a large angle difference between the guns, or shoot over a much greater distance. We are after all talking about a round fired at (assuming the mkVIII) a muzzle velocity of around 800m/s. At the highest distance convergence (180m) in the recommended scheme in the video that would mean a 2.2m/s change in the vertical velocity of the shot bullet (given by 180/800 to give time of flight of 0.225s, multiplied by g of 9.81m/s^2) . Even if the convergence to achieve this were as extremely shallow as a 2 degree angle we'd be talking about a 2.2m/s change on a total initial vertical velocity of 27.9m/s, giving a total Delta(V) of 7.9%. As that angle gets larger the initial vertical velocities increase and the acceleration rapidly becomes more insignificant. By 4 degrees we are down to approx 4%. I very much doubt any of us are accurate enough in our shooting for that to matter :D Of course you do have the lower wing guns pointing upwards and the upper wing guns pointing down. But again we are most likely talking about less than 10% spread per pair (Ie a 10% spread between the bullet from the lower gun and upper gun of the same convergence setting pair).

I disagree with the deflection shooting however. The accelerations are only applied to the bullet while it is moving through the barrel. The barrel is approx 0.6m in length and at 800m/s that gives a total time in barrel of around 0.00075s. This is of course simplified by taking the velocity to be constant, which it isn't, but the acceleration of the bullet is large enough that we are still talking about tiny fractions of a second. We assume a max acceleration on the aircraft of 5g (above which the pilot blacks/reds out) that's around 50ms/^2. Giving total acceleration, if we are generous and say the bullet spends 0.005s in the barrel, of delta(v) 0.25m/s . Again this is on a 800m/s bullet and is therefore insignificant. 0.005s is a fair time to say, I could actually work out the numbers but instead I will link below to a piece of work on gun barrel wear which worked out with a constant acceleration a rifle round takes 0.001s. Increasing that by a factor of 5 should account for the non linear acceleration and for bullet differences. The reason I'm not working out a better figure is that, frankly, I'm too tired at the time of writing to do such a complex calculation as that. Differential drag forces at shockwave boundaries and all. As I'm sure you are aware drag forces are extremely approximate anyway, with a near arbitary change over point for where we change our model. I could try and argue this with you but instead I will publish this diagram, which shows the (actual) convergences for level flight and for a 60degree 2g deflection shot for a p-47 aircraft. The convergence pattern is unchanged relative to itself and is merely rotated and deflected. This is the actual technical document used by the US military of their convergences.

http://en.wikipedia.org/wiki/Gun_harmonisation#mediaviewer/File:P-47_gun_harmonization_-_two_types.jpg

In short, I agree with most of what you say when we are talking about absolute accuracy. I was just trying to keep things simple in light of the extremely low significance of the effects in question in this setting. I apologise in advance for any screwed up calculations, I wrote this response at the end of a long and tiring day. I also should not have used the word identicle when describing the two situations, I should have said almost identicle. That was an error on my part.

P.S Thank you for your work on convergences which you have published for us all to try. Interesting stuff indeed.

Bullet barrel time:
http://varmintal.com/atune.htm

Gix
Jun-04-2014, 04:43
I found a nice location for the convergence test (Willington or something like that) : It's close to some hills on top of which I place my targets (to counteract the gunsight/ground angle when the tail wheel is on the ground).
I used the FW200 as a scale to set the distance (33m wingspan, 3 planes = 100m)
I use a raw of Westminster abbey(s) as my target : it's flat and it's the tallest building in the FMB (? any input for taller building welcome) plus it cannot be destroyed with guns.
I load the gun I want to control with the De Wilde (sparkles on impact, visible even at 1000m distance).
So I have the methodology for live test.




Hello,

Can you show how you check your (very interesting) tool modelling in regards of the real game.
Maybe with a picture?

And any chance you do an open office version ? the xls file is a little bit corrupted when loading with open office (plane graphics, I guess it's not a big deal to adapt...)

DeXaÏ_☨
Jun-04-2014, 13:33
I agree entirely. I was trying to put things simply without wittering on for ages about complicated details which ultimately at the ranges in question make virtually no difference. In the rotated state in that the lines of fire will suffer some spreading from the parabolas. However the effect, unless you are setting guns at extremely different settings to each other, is far too small to worry about at any range within the convergences suggested. You would have to either have very different settings to make a large angle difference between the guns, or shoot over a much greater distance. We are after all talking about a round fired at (assuming the mkVIII) a muzzle velocity of around 800m/s. At the highest distance convergence (180m) in the recommended scheme in the video that would mean a 2.2m/s change in the vertical velocity of the shot bullet (given by 180/800 to give time of flight of 0.225s, multiplied by g of 9.81m/s^2) . Even if the convergence to achieve this were as extremely shallow as a 2 degree angle we'd be talking about a 2.2m/s change on a total initial vertical velocity of 27.9m/s, giving a total Delta(V) of 7.9%. As that angle gets larger the initial vertical velocities increase and the acceleration rapidly becomes more insignificant. By 4 degrees we are down to approx 4%. I very much doubt any of us are accurate enough in our shooting for that to matter :D Of course you do have the lower wing guns pointing upwards and the upper wing guns pointing down. But again we are most likely talking about less than 10% spread per pair (Ie a 10% spread between the bullet from the lower gun and upper gun of the same convergence setting pair).

I disagree with the deflection shooting however. The accelerations are only applied to the bullet while it is moving through the barrel. The barrel is approx 0.6m in length and at 800m/s that gives a total time in barrel of around 0.00075s. This is of course simplified by taking the velocity to be constant, which it isn't, but the acceleration of the bullet is large enough that we are still talking about tiny fractions of a second. We assume a max acceleration on the aircraft of 5g (above which the pilot blacks/reds out) that's around 50ms/^2. Giving total acceleration, if we are generous and say the bullet spends 0.005s in the barrel, of delta(v) 0.25m/s . Again this is on a 800m/s bullet and is therefore insignificant. 0.005s is a fair time to say, I could actually work out the numbers but instead I will link below to a piece of work on gun barrel wear which worked out with a constant acceleration a rifle round takes 0.001s. Increasing that by a factor of 5 should account for the non linear acceleration and for bullet differences. The reason I'm not working out a better figure is that, frankly, I'm too tired at the time of writing to do such a complex calculation as that. Differential drag forces at shockwave boundaries and all. As I'm sure you are aware drag forces are extremely approximate anyway, with a near arbitary change over point for where we change our model. I could try and argue this with you but instead I will publish this diagram, which shows the (actual) convergences for level flight and for a 60degree 2g deflection shot for a p-47 aircraft. The convergence pattern is unchanged relative to itself and is merely rotated and deflected. This is the actual technical document used by the US military of their convergences.

http://en.wikipedia.org/wiki/Gun_harmonisation#mediaviewer/File:P-47_gun_harmonization_-_two_types.jpg

In short, I agree with most of what you say when we are talking about absolute accuracy. I was just trying to keep things simple in light of the extremely low significance of the effects in question in this setting. I apologise in advance for any screwed up calculations, I wrote this response at the end of a long and tiring day. I also should not have used the word identicle when describing the two situations, I should have said almost identicle. That was an error on my part.

P.S Thank you for your work on convergences which you have published for us all to try. Interesting stuff indeed.

Bullet barrel time:
http://varmintal.com/atune.htm

Hi Yblad !

Thanks for the feedback, very interesting discussion.

Yeah, I think we're agreeing, it's just I didn't get you were talking qualitative while I was talking quantitative.

In regards to the acceleration during deflection shooting (Gs along Yp), I think I now see what you meant by "the pattern at the point of impact will stay unchanged". Once again, in this configuration, on a qualitative aspect, I agree.

The P47 chart is interesting indeed, but no difference can be seen cause the gs apply on Yp, whereas the H conv is set along Xp.

I had more the one wing up, one wing down configuration (1G along Xp) in mind when I was saying that the pattern would be modified (because it is the worst case scenario).

I'll modify my version of the calculator later on or use the jbm site to see what the pattern would give in a wing up / wing down configuration. Not much difference I guess but it raised my curiosity.

Cheers !


Hello,

Can you show how you check your (very interesting) tool modelling in regards of the real game.
Maybe with a picture?

And any chance you do an open office version ? the xls file is a little bit corrupted when loading with open office (plane graphics, I guess it's not a big deal to adapt...)

Hi Gix,

I had to reinstall the game after I bricked my Mobo, so I do not have the mission I made anymore.

Basically, I used the FMB to make a custom mission.
I used a row of Westminster Abbey as my target that I set on top of a hill (to counteract the nose up when the spit is on the ground).
I then used the grid provided in the FMB, to draw roads every 100m from target.
I then set the loadout to have one/two guns loaded with DeWilde ammo (flash on impact)
I then taxied to those roads (so I knew the distance from target).
I used my gunsight as a rough scale (base/range*distance from target= projected base on target) to measure the elevation.
I fired at the target, and checked the elevation of the impact Vs my gunsight and calculated their elevation.

So that was for the theory. What happened is that I was only able to test at 300m and 900m (grass is still deadly, even when covered by roads...) and that the FMB drove me mad ;)
The variations are quite small and the inaccuracy of the bullet is quite important, so those tests only confirmed the game sets the convergence as per the gunsight (not as per gun location) and that the trends when you modify your convergence seem to match the ones of the calculator. (For example, 100m V convergence and 890m give similar results).

So based on those observations, I believe the calculator is reasonably close to the game but I was unable to quantify how much it matches (almost 100% sure for the H conv, V conv *seems* to work fine but it's more tricky though).

Unfortunately I do not have an open office version and I'm not very familiar with this software.

Yblad
Jun-04-2014, 15:59
Hi Yblad !

Thanks for the feedback, very interesting discussion.

Yeah, I think we're agreeing, it's just I didn't get you were talking qualitative while I was talking quantitative.

In regards to the acceleration during deflection shooting (Gs along Yp), I think I now see what you meant by "the pattern at the point of impact will stay unchanged". Once again, in this configuration, on a qualitative aspect, I agree.

The P47 chart is interesting indeed, but no difference can be seen cause the gs apply on Yp, whereas the H conv is set along Xp.

I had more the one wing up, one wing down configuration (1G along Xp) in mind when I was saying that the pattern would be modified (because it is the worst case scenario).

I'll modify my version of the calculator later on or use the jbm site to see what the pattern would give in a wing up / wing down configuration. Not much difference I guess but it raised my curiosity.

Cheers !



I am sure the misunderstanding is my fault for not being clear, and being a bit too enthusiastic in my wording! Interesting debate indeed. I would be fascinated to see your results on the wing up/down configuration. My internal yardstick (that back of a napkin ballpark physics we often use) says the patterns should be disturbed by about 10% at the 175 to 200 range. However I may be wrong about that. It wouldn't be the first time my yardstick has been off.


On a seperate but related topic an interesting thought occurs that if someone were a good enough shooter they may be able to use the spread convergence method from the video to become especially deadly at a certain range by loading AP and Dewild into the central converging guns and ball into the wing converging guns. Shread the wings while setting to fire to and/disintegrating the engine at the same time.

Yblad
Jun-04-2014, 16:18
Also I believe I forgot to say; thank you phil for the video and for sharing it and your ideas with us. I use the settings you recommended in the video and they work a charm :salute:

DeXaÏ_☨
Jun-04-2014, 17:39
My observation at this time is that it is not necessary to have all bullets converge at the same point but rather have more of a broader spread increasing the options of hitting a vital component. (For now at this stage of COD TF development).

I tend to share your point of view, it suits more my gameplay by having more versatility.

To all : bear in mind the most important is to make your convergence suits your "style".

For example : if you have difficulty to spot contacts from a distance or often find yourself at a disadvantage, you might want to have longer and spread convergence to increase your chance of a lucky shot.

If you attack over France, you might want to have more tight convergence, as you'll be engaging at short distance and you don't want the enemy to be able to get back to base.

If you defend, only getting him venting could be sufficient (longer and more spread).

If you strafe, then you would probably prefer longer convergence (easier to pull out).

If you play single player and want to shot down bombers only, you can even use the reverse calculator to set convergence on both engines while the gunsight is centered on the cell of the bomber.

etc.

All the light yellow cells in the Excel can be modified and will yield different effects in the charts (switched to red in the attached pic : 9953)

Good Hunting !

ATAG_Flare
Sep-11-2014, 12:34
Hey, stupid question, but in the user.conf file, does the horizontal or vertical convergence come first? If I want 180H and 200V, do I put 180 200 in the file or 200 180?

Flare

9./JG52 Mindle
Sep-11-2014, 17:38
Horizontal first, vertical second

Gix
Sep-12-2014, 03:17
180 200
H first

DeXaÏ_☨
Oct-31-2015, 12:44
Hi,

I took some time to correct a few things on the Spitfire calculator (details) and created one for the Hurricane. Hope you'll like them ;)

Hurricane H&V convergence calculator : https://goo.gl/ZyClQr
Spitfire H&V convergence calculator : https://goo.gl/g9QRNt

As before, please let me know if you have any question, remark or if you found a bug.

Cheers,

DeX

Edit : I had forgotten to allow DL permission, it should work now. Thanks David for the heads up

ATAG_Snapper
Nov-01-2015, 09:39
Thanks for this, Dex! :salute:

I'm currently evaluating your data under combat conditions. It may take awhile to find a 109 that will just hold still long enough for me to steady my sights on him!

:)

ATAG_Flare
Nov-01-2015, 22:25
Thanks for this, Dex! :salute:

I'm currently evaluating your data under combat conditions. It may take awhile to find a 109 that will just hold still long enough for me to steady my sights on him!

:)

I've got three words for you:

Single Player Mode

just set up a RAF 109 and shoot him to bits!

=FI=Murph
Nov-11-2015, 12:42
I must admit I'm a little overwhelmed by the math here, but I want to try your suggested convergences. I do have a question; Why do the vertical convergences between guns 1&8, 2&7,3&6 and 4&5 not match each other the same way the Horizontal ones do? I like to load tracers only in my outboard guns, and this might mean that they will not converge on the same point?

DeXaÏ_☨
Nov-13-2015, 04:49
Why do the vertical convergences between guns 1&8, 2&7,3&6 and 4&5 not match each other the same way the Horizontal ones do? I like to load tracers only in my outboard guns, and this might mean that they will not converge on the same point?

Hi Murph,

This is just a personnal preference. Having them like that increases the "spread/showering" (see lateral view of the calculator).

Yet, we are talking about 15 vs 30cm between points of impact here. So you can, and should modify those values to suit your preferences.

As a reminder for everybody : yellow cells on the calculator tab can be modified and charts will automatically update to display trajectories/guns on target.

Regarding tracers : for info, those rounds contain pyrophoric materials which tends to make them lighter, which in turn makes them less energetic (+ they won't retain velocity as well as standard rounds). Also, as per TF posts, an incendiary/tracer will be less efficient at starting fire than a "100%" incendiary for example (due to the reduced payload).

Cheers,

DeX

Baffin
Nov-25-2015, 10:48
Hi Murph,

This is just a personnal preference. Having them like that increases the "spread/showering" (see lateral view of the calculator).

Yet, we are talking about 15 vs 30cm between points of impact here. So you can, and should modify those values to suit your preferences.

As a reminder for everybody : yellow cells on the calculator tab can be modified and charts will automatically update to display trajectories/guns on target.

Regarding tracers : for info, those rounds contain pyrophoric materials which tends to make them lighter, which in turn makes them less energetic (+ they won't retain velocity as well as standard rounds). Also, as per TF posts, an incendiary/tracer will be less efficient at starting fire than a "100%" incendiary for example (due to the reduced payload).

Cheers,

DeX



"Suit your preference" is the operative advice here...

I choose the outboard guns for tracer ammo simply because I like to strafe columns of vehicles. The tracer divergence in this configuration will show the lateral limits of your impact points left and right of the column. All of the bullets are "between the white lines" so I don't continue firing when too far from the target.

It serves the same purpose in air to air combat, and really helps from the 6 O'clock firing position. Tracer only helps me as a pointer during deflection shots... not enough time for me to get analytical... so I guess inboard tracer with lower convergence/divergence angles would be best for that.

It kinda makes the argument for multi-barrel guns! High rate of fire with no convergence at all!