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Recommended optics modification for SU-76

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mlespaul

mlespaul

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Jul 26, 2007
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Washington, DC
www.germanmilitaryoptics.wordpress.com
#1
Found some pics from a book on the subject AFV. Happen to have some reticle pictures that I think match up.

Main gun ZIS-3 Optical Sight (Panoramic type left of gun):
2000728718890463342_rs.jpg

2003588909313792715_rs.jpg

2003520125616630091_rs.jpg

2003564182361164647_rs.jpg


Panoramic on left - trench-type periscope on right

2000788698584437347_rs.jpg




Observation (right of gun - trench periscope type)


2000778938761089224_rs.jpg








2001744854656414784_rs.jpg










Reticle and field of view



2001796853470500961_rs.jpg



Now you can keep your head down and still see/shoot in a fair manner.
 
#5
Right. Because the SU was based on the original ZIS-3 platform, the carriage, and ranging gear were also installed, along with the optic specs. Basically it was self-propelled artillery. The Hummel and Wespe are similar in that aspect.

If you look at the drawing in the manual picture above you can see the panoramic set in the tube next to the range drum mechanism. As the elevation was adjusted in the knobs supporting the optic to maintain alignment visually against a distant target or object of known distance, alignment changes in the carriage would occur co-incidentally at the same time the optic's elevation was made. this made certain points on the sight carriage move apart, which forced the gunner to then turn the trunnion wheel, elevating the gun, until the points on the sight carriage came back together to 'match up' to the correct position as indicated on the range wheel. The gun was now correctly 'laid' to fire the rounds where desired - I think folks realize the basic artillery gunnery thing.

Now, if the SU's sight carriage and gun was zeroed out along with the optic, and range drum so that it was able to fire at close enough range, then yes, I'd say this panoramic would make just as fine a direct fire sight as any other.

Just have to remember that everything was done manually. I can do a full-blown explanation of how these panoramics/Rudblickfernrohrs work with the gun's system, if it's really needed, but I would guess that most gamers' eyes would probably glaze over....;) LOL
 
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#6
mlespaul said:
Just have to remember that everything was done manually. I can do a full-blown explanation of how these panoramics/Rudblickfernrohrs work with the gun's system, if it's really needed, but I would guess that most gamers' eyes would probably glaze over....;) LOL
Click to expand...

Yeah, I went through field arty line in the NCO school (we handled mostly Soviet D-30, Finnish/Swedish 105mm H61-37 and Finnish 152mm H88-40) when I was in the FDF, and every time I try to explain to curious people something about how the artillery gets the shells land where they are needed people get this empty stare and just nod without understanding a word. No matter how thoroughly you try to explain even though it's practically relatively simple thing. I guess it's just these hands-on things you don't understand until you play with them for a while. :)
 
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#7
mlespaul said:
Right. Because the SU was based on the original ZIS-3 platform, the carriage, and ranging gear were also installed, along with the optic specs. Basically it was self-propelled artillery. The Hummel and Wespe are similar in that aspect.

If you look at the drawing in the manual picture above you can see the panoramic set in the tube next to the range drum mechanism. As the elevation was adjusted in the knobs supporting the optic to maintain alignment visually against a distant target or object of known distance, alignment changes in the carriage would occur co-incidentally at the same time the optic's elevation was made. this made certain points on the sight carriage move apart, which forced the gunner to then turn the trunnion wheel, elevating the gun, until the points on the sight carriage came back together to 'match up' to the correct position as indicated on the range wheel. The gun was now correctly 'laid' to fire the rounds where desired - I think folks realize the basic artillery gunnery thing.

Now, if the SU's sight carriage and gun was zeroed out along with the optic, and range drum so that it was able to fire at close enough range, then yes, I'd say this panoramic would make just as fine a direct fire sight as any other.

Just have to remember that everything was done manually. I can do a full-blown explanation of how these panoramics/Rudblickfernrohrs work with the gun's system, if it's really needed, but I would guess that most gamers' eyes would probably glaze over....;) LOL
Click to expand...

Nice set of postings.

I have read of a number of self-propelled artillery systems, or towed artillery systems in which two crewmen are involved with laying the gun. One adjusts for traverse\deflection and the other deals with elevation\range. I would imagine this could be a real draw back to the system when engaging say tanks which are moving. Is this the case with the SU76? Or does one gunner deal with both deflection and elevation?

Thanks
BR471B
 
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#10
BR471B said:
Some SP artillery and some towed artillery employs a system in which elevation\range is input by the gunner, but defelction\traverse is input by another crew men. Does the SU-76 gunner control both deflection and elevation?
Click to expand...

Well, judging by the first three images it would seem that they are all controlled by the gunner, in pic #1 there isn't anything significant on the right side of the gun. Deflection is set by using that small vertical roller in the middle of the panoramic telescope (which looks externally very similar with the PG-1M used with D-30, probably they are exchangeable). Elevation is different thing, I believe it could be set with that larger roller in the lover part of the attachment for the telescope (seen in pic #2, around center of the lover half). There is also a small roller on the telescope that tilts the head of the telescope (and the sight picture as well), and I believe it can be used for the same purpose when firing direct fire. When firing indirect fire this latter roller has no use except for adjusting it so that the collimator is visible trough the eye piece.

There is a crank in pic #2 in the lover left corner that is probably used for elevation, and deflection crank should be somewhere belowe and right from it (though not seen in the image).

Here are some detailed pictures of ZIS-3 I found:
http://www.photoka.info/zis3/index.htm
Picture 29 shows the attachment for the telescope, and there seems to be two rollers that could be the elevation controls; one bigger one under it and one smaller on the left. My guess is the bigger one under it, it seems to be connected to the large round object on the right that has writing on it. That is a crude device that AFAIK can be used for determining proper elevation for indirect fire when accurate calculations cannot be done for some reason. D-30 has similar (though significantly more complex) thing but we weren't even trained to use it since it would probably be very inaccurate (and the writing on it is in cyrillic so it would make little sense anyway). There are a lot of variables that need to be taken into account when calculating values for indirect fire and even small mistakes throw the fire off dozens of meters, so using such a simple device and ignoring most of these variable cannot be very accurate.
Picture 32 shows the cranks that actually move the barrel.
 
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#11
Basil said:
Well, judging by the first three images it would seem that they are all controlled by the gunner, in pic #1 there isn't anything significant on the right side of the gun. Deflection is set by using that small vertical roller in the middle of the panoramic telescope (which looks externally very similar with the PG-1M used with D-30, probably they are exchangeable). Elevation is different thing, I believe it could be set with that larger roller in the lover part of the attachment for the telescope (seen in pic #2, around center of the lover half). There is also a small roller on the telescope that tilts the head of the telescope (and the sight picture as well), and I believe it can be used for the same purpose when firing direct fire. When firing indirect fire this latter roller has no use except for adjusting it so that the collimator is visible trough the eye piece.

There is a crank in pic #2 in the lover left corner that is probably used for elevation, and deflection crank should be somewhere belowe and right from it (though not seen in the image).

Here are some detailed pictures of ZIS-3 I found:
http://www.photoka.info/zis3/index.htm
Picture 29 shows the attachment for the telescope, and there seems to be two rollers that could be the elevation controls; one bigger one under it and one smaller on the left. My guess is the bigger one under it, it seems to be connected to the large round object on the right that has writing on it. That is a crude device that AFAIK can be used for determining proper elevation for indirect fire when accurate calculations cannot be done for some reason. D-30 has similar (though significantly more complex) thing but we weren't even trained to use it since it would probably be very inaccurate (and the writing on it is in cyrillic so it would make little sense anyway). There are a lot of variables that need to be taken into account when calculating values for indirect fire and even small mistakes throw the fire off dozens of meters, so using such a simple device and ignoring most of these variable cannot be very accurate.
Picture 32 shows the cranks that actually move the barrel.
Click to expand...

Yes -- I think your right. Good eye Basil. Thnx.
 
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#17
Here's more back up information.
The sight is known as the PG (translated back from cyrillic as simply panoramic telescope). There have been several designations but has remained basically unchanged for around 100 years. C.P. Goerz is credited with the original invention of the panoramic for Germany right up to the beginning of WW1, whereas Russia and the U.S. and Britain quickly came up with their own version of the so-called 'dial sight'. Anyway my point about it being unchanged is that based on Soviet manuals I have dating from even the 1980s - the Soviet Union made VERY few changes to their optics from 1942 all they way through the 70s and 80s and close to the present day. If you see an anti-tank telescope for a model 1942 divisional gun in a Soviet Manual from the 1980's, for example, the chances are very good it's exactly the same as was actually used in WWII - no need to change anything, (including the illustrations) so they didn't.(Exception being of course, newer technological weapons necessitating different ammo types, sizes, or delivery systems) The PG is one of these 'frozen in time' devices.
So to prove to myself (me being a research geek) that I wasn't indeed crazy I had to go back and re-research it and so:

From "85-mm Divisional Gun D-44 Service Manual" (1983 Edition - remember the D-44 was developed in late 1943 to 1944 to replace the 76mm model 1942. The 85mm barrel is the same as used on the T-34. Also, this weapon had a direct fire telescope for AT use alongside the PG.) Here is the PG:

2000783101749433214_rs.jpg


"Pic 74. Reticle/Crosshair and Grid of Panoramic PG: a - crosshair b - grid"

Last paragraph on page says (Roughly translated with apologies to our Russian readers): "In the latest versions of the panoramic, on the lenses, instead of a crosshair, a grid is placed (Pic 74b), to provide the gunlayer the ability to anticipate lateral movement when firing on a moving objective, without requiring the gunlayer to take his eye off the eyepiece."

Enlargement:

2000735172702311948_rs.jpg



Later on in the manual is shown the reticle for the PG-1 which correlates to the German RBlF 36 that has a line of azimuth data along the bottom 1/3 of the FOV, which needs a whole 'nother posting to cover to adequately explain, as does the reticle for the direct fire telescope.
 
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#18
Hi there :)

It's a very interesting thread with lot's of great info and pictures. I have a while to spend here, so I think I can add something usefull. I second the mlespaul info about artillery panoramic sights. I have found similar info about them - standarized and somewhat "traditional" artillery equipment, not changing much over time. By standarised I mean that Russians could use German sights in their artillery pieces and vice versa, and it was done often - all were based anyway on original Goerz artillery panorama, and all were very similar and sometimes almost the same (and interchangeable). Almost any standard artillery sight could be used for almost any artillery piece from any nation, excluding some lighter AT guns. The same Russian sight could be used on 76, 85, 100, 122, 152mm guns and howitzers, and also on all self propelled versions as well (at least Su-76 used standard one, and others most likely could use it too). Even older WW1 sight could be used in WW2 gun. The reticle in Russian PG could be simple cross or a grid like mlespaul said. Probably at some stage of war, when field guns and howitzers were so often used to combat tanks, and even self-propelled versions (which usually had a second direct-fire telescopic sight - not Su-76) often had to use artillery sights to fire at tanks at more than 900-1200m range (telescopic sight was usually scaled only to about 1000m) then came to idea than adding an "arrow" aiming point and some horizontal marks similar like in newer tank sights (TSh-xx family) could be a good thing for both aiming at moving targets and training of tank/artillery gunners. I mean having similar aiming aids in artillery/tank sights could be good thing. So the more advanced version of aiming grid was introduced in artillery sights, I would GUESS that it was in about the same time, or little after, than TSh-1x family of sights were introduced, as the symbology is very similar. So early war vehicles/guns using just a cross could be quite accurate modeling - this is a guess as I said.

Here is a VERY interesting page, with lots of info about guns and artillery (explained from the very basics to advanced issues), chapters about ways of laying the guns (historical, ww2, sights), AT gunnery (ways of aiming), and much more interesting things (like what factors affect gun accuracy), I learned a lot about artillery sights here:

http://members.tripod.com/~nigelef/sights.htm

http://members.tripod.com/~nigelef/anti-tank.htm


OK, I have some additional pictures of PG-1 "Goerz artillery panorama" to share. They come from a book

Guns in Russia

1943 MOD.D-1 152mm Howitzer

(contains large amount of reprints from original gun manual)

full pages,

page 31 contains optics data



magification x4, field of view 10deg

page 33 contains the sight itself and the grid/reticle drawing



and drawings of the sight itself


and the reticle/grid only.



It's not said if specific picture is from war-time or post-war manual, as various sources are said to be used/reprinted. Here gose the late-war/post-war PG-1 reticle/grid scheme. The lower horizontal scale is said to be from separate collimator and has probably something to do with finding bearings while aiming with gun. Didn't translate full text to find how this works.

This specific drawing is quite accurate IMO, but it's good to remember that any reticle drawings are most likely a simplified schemes, not in scale and often with less important details missing - just to show the general sight layout. What is need to actually draw a realistic sight for a game is a knowledge (or a scheme) how the various reticle elements are sized and positioned (for example an info that vertical marks are separated by 5 mils (0-05 in Russian text) and the size of the central "arrow" (or inverted V) is probably same as in TSh-1x tank sights, so:



you can do the math and recalculate the height and width yourself :)

or have it here, I did it before:



The best source for modeling game sight are of course actual photos of working sight reticles, like mlespaul posted. It's an actual view, not a simplified scheme like on most drawings. Only thing to remember is than it's hard to make a photo showing full FOV of the sight with an ordinary camera, in most cases only the center of the FOV is visible on photo so the reticle grid and elements appear to be larger (in relation to visible part of FOV) than in reality. The knowledge of true size (in mils) of reticle elements (combined with known sight's FOV, 10deg in case of PG-1) helps in determining the real scale and how the sight with it's whole FOV should look.

I believe the drawing I'm posting 1943modd1152mmhowitzerpzn1.th.png could be close to actual look of the sight when someone looks trough it - the elements of reticle seem to be about the proper size.

The horizontal "lead angle" marks are said to be set every 5 mils (different than in TSh-1x tanks where it was 4 mils). The central arrow seem to be the same size as in tanks (4 mils wide each side), the "empty" space (no cross) around the arrow head seem to be 2 mils (same as "empty" area below the arrow in tanks). The vertical size of horizontal marks would be 1 and 2 mils. It's hard to tell this for sure from drawings and picture but it seems so and seem logical.

Now, the scale with 8 horizontal marks, 5 mils each, cover 20 mils each side of the central arrow, 40 mils all . The whole sight FOV is 10deg as we know. On drawings, the horizontal scale (8x5mils) is about 1/4 of the sight's FOV. One mil is (as Russians assume in the same paper) 1/6000 of whole circle, so 360/6000 = 0.06deg (actually more precise calculation would make 1 mil = 0.0573deg). Now the width of the horizontal "lead angle" scale - 8 marks by 5 mils = 40 mils, multipled by about 4 (as it covers about 1/4th of the sights FOV on drawing) would be about 160 mils, this is 160*0.06deg = 9.6deg. Quite close to the 10deg it should be theoretically (from optics data). So the drawing is close to how actually the sight should look like.

(more exact measurement made later:

the size of the whole horizontal scale, 8 x 5 mils (both left and right) is 136 pixels. The size of the whole FOV (10deg) is 560 pixels. The proportion 560/136 is 4.118 so little more than 4.

4.118 x 8 x 5mils = 164.706mils - this is the width of sight's FOV on drawing. And 164.706x0.06=9.88deg so even closer to theoretical 10deg. Maybe the size of the grid plotted on the optical plate is indeed a little bit smaller than the FOV of the optics and there is really a "circle" visible little smaller than optical FOV, as a part of reticle close to the edge - like in all stock RO optics ? Only an actual look (with an naked eye) trough real sight could tell it probably, as no picture made with ordinary camera is likely to show the whole sight's FOV as seen by human eye... But the edge could be photographed probably separately.

The conclusion - proportions on the drawing



are almost exact, so it's probably not a simplified scheme but a correctly scaled drawing of actual reticle grid - or very close to. Can be used directly while making PG-1 panoramic periscope sight texture for RO (excluding the lower strange horizontal scale with lot's of numbers- it probably cames from separate device and would be not visible or used in AT gunnery. )

Regards!!!

Amizaur
 
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#19
Yes, those alphabets are not used in AT gunnery but only for indirect fire, so I guess they are not essential for the game. The collimator has a matrix of those characters inside it and a magnifying lens. When looking trough the panoramic telescope towards the lens of the collimator it shows one of these characters, and the gun is traversed so that same characters on the reticule and the collimator are vertically aligned. E.g. if there's an A showing in collimator then the A in the reticule has to be vertically exactly in the same spot, horizontally there's no difference so it can be over/under/on top of it.

So basically when firing indirect fire you first screw in the values calculated in the HQ tent (in FDF the bty commander and two special NCOs are responsible for this), and then operate the cranks first setting the elevation (how this is done depends on gun model) and then traversing until the characters are aligned. Latter can be a bit difficult at times since the optics tend to freeze very easily in cold weather and especially with that Soviet gear there are actually many characters that are easy to mix with each others, resulting the gun pointing slightly the wrong way (e.g. A, 4, д, п). So the guy responsible for this has to be pretty careful and has to be cleaning the optics all the time if the weather is not perfect.
 
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