Now the question will be… Will the developers fix it and give us such an armor-piercing shell. Or will they say - “The drawing is not a source”…
Oh, but has someone made new report about guns with this blueprint? I haven’t seen yet
Also we had a different sketch from Jordan book
I wonder what’s the mass of this cap? Does it back the calculations were made previously from German/Jorda sketches, saying that the cap mass is about 8.2-9.2% of the shell mass.
@Admiral_Bofors made our best bug report on the shell so far, maybe he can look at this.
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It’s an interesting source, no doubt, but it looks way too “sketchy” (as in “just a sketch”, not “fishy”) to be accepted as a viable source I think… We would need an actual French blueprint much closer to the German we already got.
I would refrain from any new calculations/estimation as that had failed previously.
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I had already pinged him on Discord, as soon as I saw the new Sketch. Let’s see what he has to say when he wakes up. There’s a chance he will refrain from doing any more than he has done so far but also knowing him he may just calculate this too for the fun of it, no guarantee.
Update: He’s doing it
This must be the original sketch from the French gunnery manual that was used as a reference for John Jordan’s drawing in the French battleship book.
I doubt this would change the developer’s mind after all the evidence presented, but I suppose it wouldn’t hurt to do an analysis for fun :D
The previous volume estimate from John Jordan’s sketch was 6657.81 cm³ with an estimated shell cap weight percentage of 9.17% (including the K device).
I modelled the shell cap again as closely as I could from the original sketch and the new shell cap volume is 6992.13 cm³.
This is roughly a 5% difference in volume (not shell cap weight percentage!) compared to the previous calculation based on John Jordan’s sketch.
The estimated volume is 6992.13 cm³.
Let’s assume the density of regular steel is 7.85g/cm³.
We multiply volume of the shell cap by density to get the mass.
6992.13 * 7.85 = 54,888 g or 54.8 kg
We divide the mass of the AP cap by the mass of the shell to get the percentage weight of the shell cap relative to the shell.
54.8 / 570 = 9.61%
Oh, I almost forgot. If we exclude the K device and use the shell weight value in game, the percentage goes up to 9.78%.
None of this should be surprising really as Richelieu’s APC Model 1936 shell supposedly has the hardened cap take up 9.5% of the shell weight.
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You could adjust your calculations to see if taking the properties of the 380 mm OPFK, would your estimation be also correct for the weighted cap.
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Absolutely!
From the modelling of the AP cap, we have an estimated volume of 11432.95 cm³.
The estimated volume is 11432.95 cm³.
Let’s assume the density of regular steel is 7.85g/cm³.
We multiply volume of the shell cap by density to get the mass.
11432.95 * 7.85 = 89,748 g or 89.7 kg.
Let’s get the difference between the measured value and the expected value.
Using the 86.5 kg figure from the second image (this one I used as a reference to model the cap):
89.7 - 86.5 = 3.2 kg
3.2/86.5 = 3.7% deviation
Using the 84 kg figure from the third image:
89.7 - 84 = 5.7 kg
5.7/84 = 6.8% deviation
If the above calculations are correct, my estimates for the weight of the AP cap on the 380 OPfk shell deviates from 3.7 to 6.8% depending on which weight value is used.
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9.61%-9.78% AP Cap from the new drawing?
Now It looks more AP than Richelieu AP shell lol
I wonder would it be rejected again, or we have a chance?
Also amazing work as always🫡
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Should we submit the new info for bug report? or that still won’t be good enough source to get the shell changed to AP?
9.6-9.7% AP cap, that’s in AP shell territory.
I don’t see any new information regarding the 330 mm OPFK.
The comparison with the mesh analysis on the 380 mm OPFK, and the German analysis could strengthen the argument of the results of the previous mesh analysis on the 330 mm, but that’s about it.
You would still need raw, unaltered data from a primary source on the cap weight, however.
There’s an interesting detail that I picked up. The shape of the AP cap from John Jordan’s sketch looks a lot more similar to the German sketch rather than the one he provided.
This is John Jordan’s sketch:
The German sketch:
And the original sketch that John Jordan provided:
I’m not sure about the discrepancy between the three different sketches here, although we are getting similar volume estimates but that’s not enough.
I suspect John Jordan might have used another primary sketch aside from the one he provided to get a shape similar to that of the German sketch (unless he directly used the German one for reference).
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I was wondering if this could be considered as “new” information, as the thickness of the AP cap is now explicitly stated to be between 0.2-0.3 calibers on the sketch.
The sketch labels the shell as being 5 calibers long. Obviously, that is a rounded down value but dividing the shell length by 330 mm gives a value of 4.965 calibers (1638.5 mm / 330 mm) which is consequently rounded up to 5 calibers in the sketch. So we can conclude that the measurement in calibers is indeed referring to the caliber of the shell which is 330 mm in this case.
If we use the 0.2-0.3 caliber value, that would mean the thickness of the AP cap would range from 6.6 to 9.9 cm (330 mm * 0.2 = 66 mm, 330 mm * 0.3 = 99 mm).
Now what is interesting is that this is comparable to the measurements I did on a sketch of the 15 inch Mk XIIa shell where the thickness of the AP cap at the top was around 6.78 cm.
If the thickness of the AP cap measured at the tip which ranges from 6.6 to 9.9 cm is comparable to the cap thickness on a much larger 15 in Mk XIIa APC round which is in game, I think it would be reasonable to conclude that the OPf Mle 1935 shell should be classified in the same way.
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You can try, but it’s a slippery slope with too many unknowns. You can’t just compare two thicknesses without knowing their density.
That is true, although I only used regular steel in my previous estimates to get the AP cap weight of the 330 mm shell. I’ll see if I can do a better comparison with other shells that have more information.
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But I do have to add that this entire idea of the 330 mm OPf shell being classified as SAP stemmed from NavWeaps claiming that the AP cap was “thin” without knowing the density values to begin with. Since we established the thickness of the top of the cap is similar to other shells, we can’t exactly call the whole cap “thin” anymore.
And there’s a reason why the French caps are thick enough on the top and yet weigh less than other contemporaries.
French 380 mm AP cap
British 381 mm AP cap
French caps tend to be thicker on the top and thin out on the sides while others are more “distributed” overall. Basic geometry would tell you that enlarging the shape of a hollow cone closer to the base will result in a greater increase in volume compared to enlarging the shape closer to the top.
So there’s a reason why we’re getting lower AP cap weight estimates for the French shells. It’s not because they’re “thin” (and I personally don’t believe it’s a massive difference in density), rather the distribution of the mass is different.
Anyways, rant off. I’m going to see if I can find any more noteworthy comparisons.
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Bofors has yet again brought up a new report in favor of Dunkerque’s AP, this time comparing the opf 330 mm’s APC thickness to shells of other nations. please go show your support!
https://community.gaijin.net/issues/p/warthunder/i/mV3lFNNYWg7z
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nice job
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