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Hmmm.............

I have two questions:

1. Were the Germans using AP ammunition?

2. How thick was the ships hull.

I did read how a couple of P-38's strafed a IJN DD and set it to smoking, but I figured that involved a good number of hits.

The last couple of posts point out something that does get overlooked sometimes, and that is that both the 20mm cannon and .50 caliber (12.7mm) machine gun were created at the end of WW1 as anti-tank weapons. I recall reading years ago in a book on American PT Boats that they experimented with 1/2" (12.7mm) armor plate for the boats. Before installing the plates the crews tested the plates by hanging them up from trees and shooting at them from more than 100 yards away with their twin-50 mounts. At the end of the test the plates looked like Swiss cheese, and they didn't bother installing them after that.

The point is that most ships are built of 1/4" to 1/2" common steel and are not bulletproof, and the only part of any destroyer that has armor is the gun shields, and event those are only meant to stop splinters from a shell exploding on deck. The bad part is that your submarine is no better, and holes in the hull can mean that you don't have a submarine any more. I've read more than one account from merchant crews of being approached by a u-boat, opening fire with machine guns and the boat diving and running away.

Yes, machine guns are dangerous.

If we're talking about Japanese AA Guns on merchants (etc) then you're looking at a Type 98 20mm gun, since it made up about 98% of all AA guns in the IJA and was also used by the IJN. Merchants would have gotten their (improvised) AA defenses from the Army, most likely.

It has two types of ammunition, an AP-T round that weighs 165 grams and an HE-T round that weighs 136 grams. Muzzle velocity on the Type 98 is 2720 f/sec (830 m/sec), and maximum possible range firing horizontally is 5,500 meters. Ammo came in 20 round box magazines.

Depending on the range, it could very easily punch holes in any submarine in the US Fleet at that time, since they used 7/8" steel (at most) for the pressure hull. I would expect performance to drop off dramatically on the AP round past 2500 meters, but the HE round would remain dangerous out to its maximum range - this is why cannons replaced machineguns in combat aircraft.

Pics of the ammo:
http://www.inert-ord.net/jap02h/t100aa/index.html

Excerpt from the Intelligence Bulletin, September 1943:
http://www.lonesentry.com/articles/jp_type98/

"The Japanese Type 98 antiaircraft-antitank gun, 20-mm, is considered one of the enemy's best constructed and most efficient weapons. Most of its features were copied from a 20-mm rapid-fire gun manufactured by the Oerlikon Company, of Switzerland. In fact, some of the bearings in the carriage of a Type 98 recently examined by U.S. Ordnance experts bore a Swiss stamp. The Japanese weapon, weighing approximately 840 pounds, is relatively light and very maneuverable."

You know, I remember reading a p-38 pilots account several years ago where his squadron sank a Japanese freighter with 20mm fire. To paraphrase what he said, they took turns firing their 20mm cannons into the ships waterline until it rolled over and sank.

Oh, and 20mm AP should absolutely be able punch straight through a subs pressure hull. I dunno about .50 though, I would guess probably not. Maybe one of the thin skinned boats.

I still consider that the effects of small rounds are greatly exaggerated in game.

About the .50 cal. Naturally they are going to be effective at 100 yds. But how much could they penetrate at 1,000, or at 2,000? I looked over at NavWeapons.org, but I couldn't find anything about penetration.

In the game, I think these AA guns are 25mm single mounts. It seems the IJN had singles, doubles and triples, as well as smaller guns, and favored all these. Mostly they were evaluated from the perspective of light AAA, so it's hard to say what they might do to a sub. In the game one man operates the gun, but in RL a single 25mm had a crew of 3.

I remember from a long time ago, gun camera views of US fighter planes strafing merchant ships. They didn't show any sinking, just blowing up in the middle, apparently penetrating boilers. This with just .50 cal. Rounds could have gone through decks or hulls. Note that with fighter aircraft, the rounds will hit with increase velocity, so this doesn't mean a PT boat could do the same thing from 2,000 yds.

The British were naturally interested in deploying aircraft weapons that could sink U-boats. AFAIK, few, if any were sunk with 20mm alone, or even 30mm. They developed an airborne version of the 6 pdr. that could reliably penetrate through the deck superstructure and pressure hull. That's a 57mm weapon.

I think the real problem in these matters (SH and games generally), is that they fail to distinguish between hits that can damage and disable things, and hits that can destroy outright. They also fail to take into account velocity loss or angle of impact.

Quote:

Originally Posted by TorpX (Post 2364728)

I still consider that the effects of small rounds are greatly exaggerated in game.

I'd say it depends on what you mean by "effects".

Quote:

About the .50 cal. Naturally they are going to be effective at 100 yds. But how much could they penetrate at 1,000, or at 2,000? I looked over at NavWeapons.org, but I couldn't find anything about penetration.

Not much. According to the following site outside of 500 yards there isn't much chance of a hull being penetrated by any "light" weapon, and at 1,000 yards these weapons are unlikely to penetrate the .25-inch mild steel armor of a standard merchant hull.
http://www.inetres.com/gp/military/i...g/50_ammo.html

On the other hand reports put out by Allied merchants occasionally mention opening fire on u-boats with such weapons, the result being the u-boat diving and not coming back; the point being that you don't know for sure that your hull isn't going to be penetrated.

More to the point here, and this to is a definite "effect", the 25mm Japanese AA gun has a maximum rang of over 8,000 yards. That almost certainly won't penetrate anything, except the skins of your deck-gun crew and bridge crew.

All that said, I agree that the game is extremely simplistic when modelling small-arms fire from aircraft and ships. Then again, the game is extremely simplistic with just about everything it does.

Thanks for posting that link. I copied that stuff down - very interesting. Most of what I've seen is in the nature of .30 cal. penetration of earth or building materials, and AT guns penetration of armor.

Quote:

Then again, the game is extremely simplistic with just about everything it does.

Isn't that the truth. :yep: