HVAP production figures O JasonC!

[John Kettler]

Was trying to answer a Forumite's question and came across this worthwhile thread on a subject of which I knew squat--U.S. WW II HVAP production figures.

(Moon, info only)

http://www.tank-net.com/forums/index.php?showtopic=37253

From that same thread (page 2) comes some remarkable/disturbing info on APDS accuracy for the 17 pdr, as compared to APC, which is really APCBC. I wonder whether BFC models this issue in the game, since it seems to be a big deal?

400 yds APC hit 90.5% APDS hit 56.6%

600 yds APC hit 73.0% APDS hit 34.2%

800 yds APC hit 57.3% APDS hit 21.9%

1000 yds APC hit 45.3% APDS hit 14.9%

1500 yds APC hit 25.4% APDS hit 7.1%

Apropos of the chart, there's a good discussion here of the British APDS situation, to include the supposed first use account.

http://www.tank-net.com/forums/index.php?showtopic=37253&page=1

Regarding that, the Hallamshires apparently hold that distinction, at least vs the Panther. See Operation Martlett, Day 1.

http://www.irdp.co.uk/JohnCrook/normandy.htm

Regards,

John Kettler

[altipueri]

And where do those discarded shoes end up?

[Michael Emrys]

And where do those discarded shoes end up?

You wouldn't want to be downstream from the muzzle of the gun.

:eek:

Michael

[Vanir Ausf B]

I wonder whether BFC models this issue in the game, since it seems to be a big deal?

No, it does not.

[MikeyD]

I recall as late as the 1980s the Pentagon finally confessing that the solid shot APDS for its 90mm tank gun had a nasty habit of sometimes flying off in odd directions. The problem may have involved whether the round cleanly separated from the sabot. They never mentioned that problem until after all APDS had finally been retired from the inventory.

[Michael Emrys]

Back about 30 years ago I was watching a tv program on the subject of high speed photography. Interestingly enough, one clip showed a 17 pdr APDS round in flight. They were very clever about how they went about making this clip. They placed a series of still cameras every so many yards down the trajectory of the round, which then trips the shutters as it passed by blocking an electric eye for each one. The resulting still shots were then edited together into a continuous movie strip. The thing that got my immediate attention was how much the round wobbled in flight. It isn't hard to imagine that that wobbling and resulting corkscrewing of the flight path may have had a lot to do with the randomness of its actual strike location. This would be even more true of a shot with an even more radical wobble than the one shown in the film.

Michael

[John Kettler]

Vanir Ausf B,

That's indeed odd, since it seems to have a dramatic effect on gunnery accuracy. Why not model what the gunnery tests apparently showed? Also, I believe that the iffiness of APDS performance was represented in the pioneering CMx1 game CMBO.

Regards,

John Kettler

[Vanir Ausf B]

Also, I believe that the iffiness of APDS performance was represented in the pioneering CMx1 game CMBO.

Nope.

There is a large amount of information in John Salt's Snippets and in the Isigny and First Army firing test reports from the Mycenius site which conclusively show that APDS was very erratic in flight and not very accurate.

And CMBO does not model the erratic accuracy and failure to penetrate that was often found with WW II APDS (6 and 17 pdr APDS).

http://www.battlefront.com/community/showthread.php?p=9164#post9164

[John Kettler]

Vanir Ausf B,

I take your point, but I do not understand why something as fundamental as basic APDS projectile behavior and attendant impact on accuracy and terminal effects wouldn't be modeled. The 17 pdr is scary enough in its own right without exaggerating its formidable capabilities. Would love to know why BFC took such a counterintuitive approach.

Regards,

John Kettler

[Vanir Ausf B]

To the best of my knowledge BFC has never commented on this in the 12+ years that it has been an issue so anything I say about why it is the way it is will be speculative.

Dispersion for unguided projectiles in CMx1 was a function of muzzle velocity and I suspect that is true in CMx2. Assuming that is the case, the proper dispersion for WW2-era APDS would require an exemption to be coded for that ammunition. How easy or difficult that would be I have no idea, but apparently BFC has decided it isn't worth the effort. I think that is unfortunate, and maybe they will change their minds in the future, but after all these years I'm not holding my breath.

One other complicating factor is that there is some disagreement over how representative the various test results are of battlefield performance. The British claimed at the time that the poor test results were due to a few bad batches that had not been proofed prior to testing, and I have seen it claimed by others in debates past that the manufacturing issues were quickly sorted out. But I have never seen those claims substantiated and I am therefore skeptical of them. I have also read claims that the APDS accuracy issues were not completely fixed until sometime in the 1950s. That too is unsubstantiated but I have always thought it curious that despite the obvious ballistic advantages of APDS vs. APCBC on paper the US army did not begin adoption of APDS for it's own tank cannons until around 1960.

[Amizaur]

I think it would be really strange if CMx2 dispersion model was still based solely on muzzle velocity . I want to believe that gun/ammo database in CMx2 has some separate value for projectile dispersion . It's possible that dispersion is still related to muzzle velocity but corrected by some dispersion coefficient (initially set to 1.0 for all projectiles and only changed if required).

[Vanir Ausf B]

CMx2 dispersion still being solely a function of muzzle velocity is no more strange than first generation APDS always flying straight and true.

[Amizaur]

Well... that's true

[JonS]

The resulting still shots were then edited together into a continuous movie strip. The thing that got my immediate attention was how much the round wobbled in flight. It isn't hard to imagine that that wobbling and resulting corkscrewing of the flight path may have had a lot to do with the randomness of its actual strike location.

Isn't it at least plausible that the wobbling you observed was an artifact of stitching a movie together from multiple independent cameras?

Sidebar: 50 years later a very closely related technique would be called 'bullet time' when it was re-invented by John Gaeta for The Matrix.

[John Kettler]

The technology's obviously improved drastically since the war, and it's fin stabilization rather than spin stabilization, but the vid neatly illustrates the criticality of clean sabot petal separation. When it goes well, the projectile flies straight and true, but let things not go to plan, and you have an unstable projectile haring off at hypervelocity, in an unknown direction.

For a more technical discussion, please see the linked page (and continuing) in which portions of the parent British SECRET document appear from whence came the accuracy comparison for the 17-pdr sprang.

http://www.ww2aircraft.net/forum/ww2-general/wwii-tank-gun-specifications-22607-3.html

Regards,

John Kettler

[Michael Emrys]

Isn't it at least plausible that the wobbling you observed was an artifact of stitching a movie together from multiple independent cameras?

From watching the film, I'd rate that as extremely unlikely. The cameras were precisely placed so that as I recall each shot had the round in the same part of the frame and at the same angle. And it was very visibly wobbling. Not only that, it was wobbling in a way that I would expect from an asymmetrical separation of the shoe.

Michael

[John Kettler]

Michael Emrys,

Do you by any chance have a link for that film? I'd love to see it. That's as opposed to the horrible garble I missed in the last line of my #15. Gack!

Regards,

John Kettler