Bofors 40 mm range tables

We are going to add its accurate ballistics for WWII AAA.

Unfortunately, I could not find range tables (firing tables) for British Bofors.

Not British, but Swedish I believe...

https://forums.eagle.ru/attachment.php?attachmentid=163906&stc=1&d=1496868021

Not British, but Swedish I believe...

 

https://forums.eagle.ru/attachment.php?attachmentid=163906&stc=1&d=1496868021

LOL that's Swedish, German and French, in that order :)

Now, I wonder why they would include German and French? ... :D

My guesd is that the source was probably a sales brochure in the 30s by Bofors. Hence why its multi lingual.

"I would like to get ideas how to realise it in the sim"

Maybe not particularly realistic, but could you emulate something like the split microprism from cameras, but without the blur:

Maybe with the split diagonal ?

From what I've been able to gleam from the internets, the Bofors was a crew operated gun only, in that every single task required to fire the gun effectively was assigned to a different station, including a different station for each of adjusting the azimuth, direction, and range. This means that there would be no realistic way to operate the Bofors by a single player.

I would certainly not advocate forcing it to be crewed by a number of players, each having their own task, firstly because the probability of pulling the players together to operate a single gun in MP is simply not realistic, which would make any effort to setup the Bofors like this a complete waist of resources.

My conclusion is that any solution would be, in effect, a gaming solution, which in this case I would find okay, if you want to go there. This means, you are free to use your creativity to find a single player operations solution, or just leave the Bofors as an AI operated weapon only.

It's a coincidence type :-) , the German one was stereoscopic.

Essentially the same idea would work though wouldn't it ?

Present the player with a single image with the two sets of reticules. Have one fixed and the other mobile (different colours ?). The player has to keep the mobile one on top of the stationary one to have the correct range ?

Like so:

Essentially the same idea would work though wouldn't it ?

 

Present the player with a single image with the two sets of reticules. Have one fixed and the other mobile (different colours ?). The player has to keep the mobile one on top of the stationary one to have the correct range ?

 

Like so:

The left sight has "stationary" (controled by the bearing), the right sight has a second "ghost" pic from the target with move left and right. To has acurate coincidence amn a precise range, the two pics need match one with others. Work similary as a naval rangefinger or some WW2, early cold war tanks sights (leopard I, etc)

From:

http://www.eugeneleeslover.com/USNAVY/CHAPTER-16-F.html

About 40mm Bofors, a US Army Training and Operation Video:

http://www.eugeneleeslover.com/VIDEOS/VIDEO-40mm.html

Thanks SD,

Actually I already knew how they worked, I was trying to think of a way to have something similar for the C.A. user, but practical on a 2D monitor.

On the image I made, the red version stayed still, and only the blue on moved.

The image of the target/are would just be the standard image as having ghost images would be 1/ GPU hungry, and 2/confusing, but the reticules would look like the ones from an actual stereoscopic rangefinder, and the idea of superimposing one moving reticule over a stationary one would be the same.

I thought given the limitations of monitors etc, it might be easier to have the fixed image one colour, and the other a different colour, so players immediately knew whether the target was further away, or closer than the set range (by which side the colours were relative to each other) .

Anyway - just a suggestion...

The problem with a split prism with regards to range-finding aircraft is that you have to put the split directly over a fast moving aircraft with a low vertical profile, which I expect will be a nearly impossible task in virtual-reality.

If you consider including one of the several Predictor/Directors used by Britain and the US, I suppose you could get away with a simple pointing sight with an indicator showing the range when on-target. While firing you would need an AI to do the work of the Predictor/Directors in setting the actual range and lead in the gun, but it would be the simplest to use, and in many ways representative of how the weapons system was used by the crew.

Other than that, without a range-sighting computer, the simple "pancake" gun sight would be about all you could do, unless somebody else has an idea.

https://commons.wikimedia.org/wiki/File:Bofors_40mm_L60_Sight.jpg

The problem with a split prism (coincidence) with regards to range-finding aircraft is that ...)

Apparently not.

In November and December 1941, the United States National Defense Research Committee conducted extensive tests between the Bausch and Lomb M1 stereoscopic rangefinder and the Barr and Stroud FQ 25 and UB 7 coincidence rangefinders:

 

 

COINCIDENCE AND STEREOSCOPIC RANGE FINDERS

 

The first of these reports is concerned with the comparative test of coincidence and stereoscopic range finders. (353) In these tests the American stereoscopic Height Finder Ml was operated against the British coincidence type Range Finders FQ 25 and UB 7, in ranging on fixed ground targets, moving naval targets and moving aerial targets. The coincidence and stereoscopic methods utilize the same basic principles of geometrical optics for the determination of the distance to a target. The two methods differ radically, however, in the nature of the criterion presented for human judgement. These British instruments were of the split field coincident type. American crews were being trained at Fort Monroe to operate the coincidence instruments but this plan was dropped when six British seamen, who were experienced range takers, were made available for the tests. Until recently the British Services had tended strongly to the coincidence type of instrument while the American Services had adopted the stereoscopic principle for long-base instruments at least. The decisions of both the British and American Services apparently grow out of different interpretations of the experience of the Battle of Jutland in World War I and are of no concern in this place.

 

Tests were run in November and December 1941 using the British seamen on the British instrument and experienced American observers on the Standard M1. Bad weather conditions and various experimental difficulties and mishaps made it impossible to obtain a really satisfactory quantity of data before the tests hall to be terminated. Fixed target reading were made on targets from 2,700 to 14,500 yards. Only five aerial courses could be recorded and these were all level flight courses, at altitudes of 3,000 to 4000 yards and slant range between 4,000 and 12,000 yards Continuous contact was used. Nine courses were obtained on slow moving naval targets at ranges from 4,000 to 12,000 yards. In these latter courses continuous and broken contact were used at different times.

 

It was found, throughout the tests, that the performances of the various instruments were more nearly alike when measured in external units (Reciprocal range) than when measured in terms of error at the observer's eye, in spite of marked differences in physical dimensions of the instruments. The American MI has a base length of 4.5 yards and used 12 power; FQ 25 with a 6 yard base used 28 power and UB 7, a portable instrument, has 25 power and 3-yard base. The coincidence instruments did not use internal adjusters but were calibrated on targets of known range. In other words. the net performance of the different instruments were essentially comparable although the instruments exhibited varying degrees of efficiency in performance relative to the size. On aerial courses precision errors of the four instruments were about alike when measured in reciprocal-range units. In UOE,[5] the FQ 25 had comparatively poor precision, while the UB 7, for three of the five aerial courses, had very small precision errors. The number of aerial courses was too small to yield much information about consistency of observations from one course to the next.

 

For the naval target courses, one American instrument was not operating. Precision errors of the other three instruments were similar to those on aerial height courses. In reciprocal range units the three instruments had comparable precision. In UOE the FQ 25 was worse and the UB 7 was better than the American M1. Consistency error of the UB 7 was smaller than that of the M1, even when measured in reciprocal range units, while the FQ 25 was similar in consistency to the Ml, again in reciprocals units. On ground targets the same general situation holds. Consistency errors of the four instruments over the 9-day period were the same when measured in reciprocal-range units. Again the UB 7 was better than the stereoscopic instruments in UOE and the FQ 25 was worse. Consistency over the 9 days was not perceptibly worse than daily consistency for any of the instruments. In other words, the readings over the 9 days did not scatter in total more than did readings for a typical day. An analysis or these results leads to the following conclusions. (1) Performance of the coincidence and stereoscopic instruments was about the same when range errors were measured in yards (2) The UB 7 however, with a virtual base length smaller than that of the American stereoscopic instruments was more efficient than the stereoscopic height finders in terms of performance for its size, while the large coincidence instrument, the FQ 25. was less efficient in this sense. This situation held for all types of targets— fixed ground, naval, and aerial. (3) The UB 7 is somewhat better than the American instrument in consistency on naval targets, even when measured in external units.

 

This report is attached, as supporting data, to a Report to the Services issued by the Fire Control Division of NDRC (20). This points out that the tests indicate no important difference in the precision obtainable from the two types of instrument— coincidence and stereoscopic They do indicate, however, that the difference in performance between large and small instruments is by no means as great as would be anticipated from simple geometrical optics. The report concludes with the belief that stereoscopic and coincidence acuities are about equal. Under favourable conditions existing instruments of the two types perform about equally well, and the choice between them for any given purpose must be based on matters of convenience related to the particular conditions under which they are to be used.

I may be wrong in understanding the report, but I believe the "acuities" being measured are the accuracy of the instruments, and not the ease or difficulty of use.

Also, the testing against aircraft were ".. five aerial courses could be recorded and these were all level flight ..", which would make accurate ranging much easier than in a true combat environment with AC flying tactically.

Again, range finding was only one of the tasks assigned to one of the gun crew members. Correct me if I'm wrong, but there was no single person who operated the gun who in any way which might be comparable to the player in DCS who basically would be doing everything at once. One crewman lay (aimed the horizontal direction), one the azimuth, and one the range, which apparently compensated for the lead of the aim. I don't recall having read how the speed of the target was compensated, but that too would have to be estimated and compensated for.

Maybe I'm painting this view too black, that the player would be overburdened to fulfill all these task simultaneously, but I would be ignoring my better judgement to be silent about them.

Also, one thing to consider is, regardless of what method of range-finding is used, the player will have to not only hold on the target to find the range, but also determine the aiming point.

For example, if the AC is flying level, and given a fire-control computer to compensate for the range, speed, and altitude of the aircraft, the aim-point will be somewhere ahead of the AC along its horizontal path. But any deviation from horizontal flight means that the aim-point will be either above or below and ahead of the AC along its flight path, so you cannot simply have an aim-point to the left or right at some calculated distance.

This means the player would have to aim not only to find the range, but also simultaneously ahead of the the target along its flight path. My mind boggles at trying to do that. Thing of using a joystick and a mouse simultaneously. For example, using the mouse to hold in the target with the mouse wheel for dialing in the range, while using the joystick to aim the lead on the target... makes my brain hurt to think about it.

The other option is if you intend to basically make these two tasks the player would have to do, one after the other. But that would mean that the range setting would be only transient, and an AC flying toward or away from the gun would immediately not have the correct range, the extent of deviation being determined by the angle at which the AC is flying relative to the player's line of sight.

It's no wonder they invented computers for aiming these guns :huh:

What I took from it was that the British tended to favour the split prism system, and the US (& it seems the Germans) favoured the stereoscopic system.

Presumably this mean that both thought that their favoured system was superior.

The tests seem to have been carried out to find out which was actually better but seem to have found that with properly trained operators, they were much of a muchness.

Re - a single player using the system.

I agree, having the player track, range and calculate lead & elevation will probably be a lot to learn.

I think that's why Yo-Yo was asking for suggestions about implementations that might make it simpler, while still retaining the essential elements of the original task.

I'd imaging that it should be possible to emulate a simple computer, so that if the player holds the range correctly, and tracks the angle, that the lead and elevation will be calculated and the reticle adjusted accordingly (presumably with some damping to remove feedback between the lead/elevation adjustments and the player's aim-point leading to 'PIO').

I think the crew position the player will most identify with, is the one puling the trigger, which I assume is also the one laying on target, ie giving the horizontal aim. From my understanding, one crew member controlled the horizontal aim, and one the vertical, and one did range-finding. All this was put into the predictor, which calculated the firing solution, real-time, and then somebody pulled the trigger.

Of course it would be very weird, from a player perspective, if the player only did horizontal aiming, while AI did vertical and range.

Personally, I would rather have the AI do the range, but mostly because I think the range would have to be entered using the mouse wheel (continually adjusted, as per the circumstances), and I am used to using my first finger to operate both the mouse wheel AND Mouse Button 1; probably most people are. So to aim (mouse movement on table) and range-find (mouse wheel scrolling [first finger]), and fire (mouse button 1 [also first finger]), would require relearning a physical activity (operating mouse wheel with middle finger) I've been doing for literally decades :cry:

If the AI did range, and the predictor did lead calculation, both automatically from a player's perspective, you would need some kind of indicator to tell the player when the range was correctly entered (could change often), and thus the lead being correctly calculated. The player could then decide to wait for the correct range data, or use what the currently setting, which is probably not that far off from the last correct, setting while firing on the same moving target.