RE: The PERFECT WAR Mod : Guns (Full Version)

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JuanG -> RE: The PERFECT WAR Mod : Guns (8/22/2011 12:23:57 AM)

Here you go; the values I used from NAaB (note im not using quite the stock BC values, as I find these are a slightly better fit), along with their associated penetrations, and then NavWeaps ballistics along with calculated data for them. Im trying to dig up a table of 6"/47 penetration values I've seen somewhere, but I cant remember where off hand.

The biggest differences between NAaBs model and the real data is regarding angle of fall, but even then the penetration values generally work out to rather close. And of course, where needed they can be adjusted.

[image]http://img38.imageshack.us/img38/609/gunbal.png[/image]

EDIT: The BC for the 6"/47 is missing for whatever reason. I used 6.72.

In general, Ive found NAaB to be a great tool to work with because it is (barring the strange arrangement of some of the projectile data) much easier to work with than FaceHard, especially since I'm on a 64-bit machine and that means FaceHard needs an emulator to run.

Regards,
Juan



JWE -> RE: The PERFECT WAR Mod : Guns (8/22/2011 2:46:15 PM)

NaAB is indeed an excellent tool. Must say the FACEHARD interface is a pain in the tush. [;)] Ok, top of the pic is VS and Obliquity got from the Range Charts in Nav OP 830. Middle is from my calcs, last is from NaAB. They are in pretty good agreement.

Pen values for the middle set are what I got before and what's on that plot I did. Pen values for NaAB are from (surprise, surprise) NaAB. Good bit of difference at first. Then found the Mod-9 shell where you suggested I look and, lo and behold! Finally got NaAB values similar to the ones I got. Yay !!

So it doesn't look like there's much (if any) difference between what we are both getting for the 6"/47 shooting the Mk 35 M-9. Also showing the FaceHD68 output, so you can see the input parameters. The NaAB input parameters were identical.

Now, we need to get after those pesky Japanese guns.

[image]local://upfiles/17451/9E15D9420B034863941C0F9766C45E23.jpg[/image]



JWE -> RE: The PERFECT WAR Mod : Guns (8/22/2011 8:53:39 PM)

Ok, then did the 6.1"/60. Ran the numbers against ordinary everyday 1937 vintage Class A, with FaceHD68, just like before, and got the same numbers as before. Then ran the numbers with NaAB, against ordinary everyday 1937 vintage Class A, and got penetration values considerably "less" than mine. Woof!!, says I. What the hey, Batman? (btw, "everything" is at N1-Eff NL, FaceHD68; Full Pen, NaAB. They are equivalent.)

Then I went to my trusty Lacroix & Wells, page 462, Table 9-7 and got some published numbers. They say 108mm at 15km and 100mm at 10km. No way I believe 4 inches at 22k yds, but 4.2 inches at 16k yds doesn't sound too bad. Then noticed the pen value was against NVNC, so I shot the little swine against some New Vickers with NaAB. It was a quickie, so I only got a few values, but enough, I think. Better, but still no cigar with respect to L&W. So then I shot the little swine against some New Vickers with FaceHD68, and got values that come much closer to the L&W values.

So, comparing apples, to apples, to apples, it looks like the values I plotted originally are pretty darn good, if not more complimentary to the Japanese 6.1/60. If I plotted the NaAB values, the penetrations would fall much farther below the 6"/47 than I show in the plot.

It's very hard to verify models without real world data, and there isn't a whole bunch of that for the 6.1"/60. But I am heartened that my ballistics output and FaceHD68 give the best agreement with what little there is available. I did find what I might consider a technical blivet in the NaAB program, for this gun. The program gives a BC of 5.33. The shell has a sectional density of 3.31, which suggests a form coefficient of 1.62, but this value is in the G5 realm (boat tail, 6crh, tangent). A better form coefficient might be from 1.8 to 1.9, in the G6 realm (flat base, 6crh, secant). That would give the little swine a BC of between 5.96 and 6.29. But then, NaAB calculates everything on a single drag model. If you click between the G5 and G6 drag plots (in NaAB), you'll see exactly why and how I got the better striking angles and velocities (and thus, penetration) for the Japanese gun.

Woof !! This is so cool !! Thanks for digging deep, Juan !! Looking forward to hearing more.

[image]local://upfiles/17451/A370D5171E2E47BDA0B94A10929AF24A.jpg[/image]



JuanG -> RE: The PERFECT WAR Mod : Guns (8/22/2011 9:18:31 PM)

Everything you've posted looks good and agrees with what I've got, except for the values you got out of NAaB for the US Shells, which were too high. Tried to figure out what was wrong and where, and came to the conclusion that you tested them both against Japanese armour, which, if I follow it to its logical conclusion, means that the curves you posted originally had the 6"/47 vs Japanese armour (JVH, or JNVNC, no major differences), and the 6.1"/60 against US Class A.

Surely, if were trying to find out which was the better weapon, ballistically, then we need to test them against the same standard ('dont change more than 1 variable in a controlled experiment, etc, etc' Science 101 - in this case the shell/gun system)? This can be either Class A or something else, but please do let people know if you plot data against different standards, on the same graph no less.

Regarding BC, you'll notice I used a slightly higher one, as I came to the same conclusion. Its a shame NAaBs drag model is a little simple, but I suppose it works well enough for most things.



chesmart -> RE: The PERFECT WAR Mod : Guns (8/23/2011 9:40:51 AM)

Lovely gun geeky post I am enjoying it and learning at the same time



JWE -> RE: The PERFECT WAR Mod : Guns (8/23/2011 4:53:23 PM)


quote:

ORIGINAL: JuanG
but please do let people know if you plot data against different standards, on the same graph no less.

You are absolutely right. I probably spent too much time noting that the J gun curves were against US Class-A and Brit HCA armor and not enough noting that A gun curves were against Japanese NVNC armor. Acknowledge my fault.

I wasn't actually trying to say which was technically the best ballistics performer, just looking at performance in practice; thus, Allied guns shoot at Japanese ships, and Japanese guns shoot at Allied ships. My rationale is that I have been spending time translating technical performance parameters into game terms, so that has become my general context. I will do my best to make it more clear, in future, especially if you are looking at it, Juan [;)]

Ciao. John



Whisper -> RE: The PERFECT WAR Mod : Guns (8/24/2011 8:42:05 PM)

And now you are beating yourself with mea culpa, maybe you can publish the accuracy specs we've been waiting a month for! Skipper! Dork!

Jeremy



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