The USS iowa versus the German 406mm / 52 C34 sk cannon.

Historical what if discussions, hypothetical operations, battleship vs. battleship engagements, design your own warship, etc.
sineatimorar
Member
Posts: 176
Joined: Fri Jan 18, 2013 1:42 pm

The USS iowa versus the German 406mm / 52 C34 sk cannon.

Post by sineatimorar » Mon Nov 18, 2013 7:01 am

I been studying the question of how viable the H Class designs would have been against the likes of the USS Iowa etc.
So far I concluded that as the H39 stood as laid down, protection wise it could barely stood up to either of the modern 16 inch cannons.

The question of how badly the H39 could damage the American battlewagons in return is not so easily concluded. I have found it hard to get historically definitive ballistic performance charts as accurate as say the 380mm / 52 c34 sk of the Bismarck's. The results I get from simulation is interesting, as the strike velocity calculated is known to be less than actual historical figures. Although I can generate reasonably accurate flight path charts, so the strike angle is reasonably close. The results are therefore the minimum performance available in armour penetration.

When comparing weapons you have on the USA side a 1,227 kg so shell verus 1,030 kg shell. Muzzle velocities come out in favour of the German weapon 810 mps verus 762 mps. Ranges above 35,000m are ignored as accuracy is less than 5%, so any hit would be considered more luck than design.

The stated immune zone for the Iowa class verus the 16/45 USA weapon was 16,000m to 30,000m with the 1,227 kg ap shell. From my simulated minimum figures for the German weapon immunity of 18,000m to 35,000m is the result.
( although protection from damage to main hull is only between 20,000 to 25,000m).

So it could be said, if my figures are believable, that the German weapon lies between the two USA modern 16 inch cannons.

Does anyone have a penetration chart for the German weapon with say 5,000 meter steps based on historically recorded results? Note only for naval gun please as the Adolf version had a larger breech chamber and less rifled length. One published book stated the muzzle velocity of the naval gun at 900 mps! So I am not sure exactly what's what out there at the moment and I prefer historical figures to the slightly rubbery simulated figures I come up with.

alecsandros
Senior Member
Posts: 4349
Joined: Wed Oct 14, 2009 2:33 pm
Location: Bucharest, Romania

Re: The USS iowa versus the German 406mm / 52 C34 sk cannon.

Post by alecsandros » Mon Nov 18, 2013 7:32 am

sineatimorar wrote: Does anyone have a penetration chart for the German weapon with say 5,000 meter steps based on historically recorded results? Note only for naval gun please as the Adolf version had a larger breech chamber and less rifled length. One published book stated the muzzle velocity of the naval gun at 900 mps! So I am not sure exactly what's what out there at the moment and I prefer historical figures to the slightly rubbery simulated figures I come up with.
You can try using the excel with GKDOS-100 equations. IT's on the forum somewhere.

It has inputs for the 406/L52 as well.

In my opinion, as a naval weapon, the German gun was quite formidable, combining high muzzle velocity with good rate of fire...

The Iowa class did not have a real immune zone against the German 380mm gun, and less so against the 406mm gun. The 305mm class A main belt declined at 19*, with 37mm external plate was simply insufficient against such powerfull weapons, especialy if the ships weere on paralel courses and lateral obliquity low.
Most likely, the Iowa's vertical protection could have been perforated at ranges up to 25km by the 406mm/L52 if ships were at perfectly parallel courses [descent 22*, belt 19*; total declination = 41*. Plate thickness = at best 270-280mm comparable KC n/A; required velocity for grenz perforation: 451 - 468 m/s shell velocity at 25km: 471m/s ]

==

In return, the German vertical armor system, comprised of 300mm belt , 150mm slope and 45mm TDS, was invulnerable to 406mm/L50 gunfire at any range.

sineatimorar
Member
Posts: 176
Joined: Fri Jan 18, 2013 1:42 pm

Re: The USS iowa versus the German 406mm / 52 C34 sk cannon.

Post by sineatimorar » Mon Nov 18, 2013 8:33 am

That was quick! Thanks for the info. As far s simulators go I read with interest the debate on facehard verus gkdos-100 verus Naab. I have the gkdos version in German ( which I struggle with).

I just nabbed a copy of naab to run with. Joys of joys the ballistic section takes care of my strike velocity issues!

Also confirms a suspicion I had that the simulation I initially used may have showed less velocity, but equalized the strike forces via a steeper decent path. At least Naab demonstrates the increase in strike velocity at the longer ranges I was missing.

Yes I was aware of the fact that the Bismarck's 38cm would have had problems with the Iowa class, only mentioned it as a guide to what quality of range chart I was looking for.

I just might be able to obtain a more accurate chart & performance for the 53cm gerat 36 that is part of my study subjects related to the H series designs.

alecsandros
Senior Member
Posts: 4349
Joined: Wed Oct 14, 2009 2:33 pm
Location: Bucharest, Romania

Re: The USS iowa versus the German 406mm / 52 C34 sk cannon.

Post by alecsandros » Mon Nov 18, 2013 12:31 pm

... it's very interesting to work on such a project.
Good luck and all the best ,

sineatimorar
Member
Posts: 176
Joined: Fri Jan 18, 2013 1:42 pm

Re: The USS iowa versus the German 406mm / 52 C34 sk cannon.

Post by sineatimorar » Mon Nov 18, 2013 10:42 pm

alecsandros wrote:... it's very interesting to work on such a project.
Good luck and all the best ,
Thanks keeps my mind active. The facehard program is better suited for multi layer penetration exercises, as previously stated you can get fairly similar results for for deck penetration exercises between facehard and Naab.
Except the with facehard you have to make the assumption that the A_class armour / Kcna with the hard layer removed equals B_class / Wh types. While there is historical evidence that supports this with the German armour, it. Is still a assumption that may have errors in it.

The ballistic component of Naab is spot on with it simulation of ballistic performance. Having correctly entered the BC factor for each projectile. Using another programme that produces drag form based on the dimensions of the shells in. Both G1 and G6. Alternatively you can modify this factor in Naab to obtain the equivalent to historically recorded performance. For the 406mm German ap shell I use 16.39 G1 factor and 22.7 G1 for the 530mm. Both obtained via bulletbarrel.com drag form programme.

alecsandros
Senior Member
Posts: 4349
Joined: Wed Oct 14, 2009 2:33 pm
Location: Bucharest, Romania

Re: The USS iowa versus the German 406mm / 52 C34 sk cannon.

Post by alecsandros » Tue Nov 19, 2013 6:55 am

Are you sure the approximations fit the curves of ballistic tests done by various nations ?

sineatimorar
Member
Posts: 176
Joined: Fri Jan 18, 2013 1:42 pm

Re: The USS iowa versus the German 406mm / 52 C34 sk cannon.

Post by sineatimorar » Wed Nov 20, 2013 6:30 am

Based on the data from charts published on navweapons.com and the chart in Campbell's Naval Weapons WW2.
I use the data listed, specially that on navweapons.com on the 16/50 cannon shipped on the Iowa class as an accuracy reference as it is the only weapon to have it's ballistic characteristics extensively checked by 1./ radar equipped proofing range and 2./ the upgraded gunnery radar setup shipped in the 1980's on this class.

As far as I know the velocity gate radar mounted on the main turrets was the only 'actual' measurement of muzzle velocity at sea since the magnetic pickup rings mounted on the muzzles of the 38cm/52 sk c34 German cannon. If you have followed my other posts you would remember that I had a fundamental mental block over projectile velocities that had to be metaphorical beating out of my thinking by Mr B Jurens to set me straight on things.

As a result to test the accuracy, as far as it goes with a purely theoretical modelling in computer simulations, using the data sources listed is probably as close as we can get without empirical testing.

No matter how accurate I think I am getting with the simulated results, Scientifically I know that unless you get the chance to 'smell the cordite' in actual live firing, Everything I am doing is somewhat hypothetical theory a best.

alecsandros
Senior Member
Posts: 4349
Joined: Wed Oct 14, 2009 2:33 pm
Location: Bucharest, Romania

Re: The USS iowa versus the German 406mm / 52 C34 sk cannon.

Post by alecsandros » Wed Nov 20, 2013 6:52 am

sineatimorar wrote:No matter how accurate I think I am getting with the simulated results, Scientifically I know that unless you get the chance to 'smell the cordite' in actual live firing, Everything I am doing is somewhat hypothetical theory a best.
Unfortunately, even smelling the cordite would not be enough, as predicted trajectories, velocities and pattern size (for salvo firing) were simply to complex to be correctly estimated even by the designers and producers of their age (who did have the necessary hardware to test them)

It's a slippery problem, and should be adressed with a ton of good faith...

sineatimorar
Member
Posts: 176
Joined: Fri Jan 18, 2013 1:42 pm

Re: The USS iowa versus the German 406mm / 52 C34 sk cannon.

Post by sineatimorar » Wed Nov 20, 2013 2:24 pm

There is the rub! Being use to utilizing science to prove something accurately and hopefully beyond any reasonable doubt; You wouldn't believe how shocked ( or maybe you might ) I was to just how much naval cannon ballistics was seemly based on guess work than any intensive scientific principles.

It is of course based on sound scientific knowledge, there are just too many environmental differences in the atmosphere to get accurate data on ballistic performance.

Post Reply