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ASW damage from AC - 2/5/2013 2:59:43 PM

heibernt

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From time to time i get a OP report stating Catalina attacking a japanese SS at XX, japanese SS is reported hit. Alot of these reports are probably FoGs, but how much damage can i excpect in ones that actually hit? Minor, yardtime or sunken subs?

< Message edited by heibernt -- 2/5/2013 3:00:16 PM >

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RE: ASW damage from AC - 2/5/2013 3:15:20 PM

jeffk3510

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If they're attacking your ships, you should be able to see the ship on the screen, and determine from there.

If it is your planes attacking their ships, and the ship shows up in the ship loss screen, keeping FOW in mind, you can assume it might be sunk. Other than that, you can't..

< Message edited by jeffk3510 -- 2/5/2013 3:36:04 PM >

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RE: ASW damage from AC - 2/5/2013 3:26:04 PM

heibernt

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Thx for the reply. Yea i know i can only find out via the ship loss screen, but i was wondering what kind of typical dmg such an attack would cause. Will the sub still be operational, or does it have to return to port, or will it likely sink on the way home? Im just wondering so i might be better able to evaluate his sublosses, and thereby there presence in my shipping lanes.

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RE: ASW damage from AC - 2/5/2013 4:03:19 PM

Lokasenna

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In my IJ game against the allied AI, I've lost 2 subs to 500-lb. bombs off the west coast. In deep water, too. I have a better grasp of detection level mechanics and such now...

This came up in another thread recently. Usually, ASW aircraft aren't very effective at actually damaging subs. Where they succeed is in raising the DL. I see that ops report message all the time, but I figure that maybe only 1 in 50 actually represents a successful attack. Especially from Catalinas...though that could just be a result of their longer range. I believe the IJN subs that I lost to ASW aircraft were to SBDs.

If you actually manage to hit a sub with a 500-lb. bomb, it's hurting. Noticed that from the above losses as well as several port strikes in various games - one decent bomb hit typically results in boom/glug-glug.

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RE: ASW damage from AC - 2/5/2013 4:24:26 PM

Chickenboy

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quote:

ORIGINAL: Lokasenna

In my IJ game against the allied AI, I've lost 2 subs to 500-lb. bombs off the west coast. In deep water, too. I have a better grasp of detection level mechanics and such now...

This came up in another thread recently. Usually, ASW aircraft aren't very effective at actually damaging subs. Where they succeed is in raising the DL. I see that ops report message all the time, but I figure that maybe only 1 in 50 actually represents a successful attack. Especially from Catalinas...though that could just be a result of their longer range. I believe the IJN subs that I lost to ASW aircraft were to SBDs.

If you actually manage to hit a sub with a 500-lb. bomb, it's hurting. Noticed that from the above losses as well as several port strikes in various games - one decent bomb hit typically results in boom/glug-glug.

I've lost a small handful of subs to Allied ASW air attack-Catalinas. 500 lb. bombs did the trick.

It's difficult in the game as it was IRL to get a sub kill with an aerial bomb. From Clay Blair's Hitler's U-Boat War (Volume 1): a 500lb. bomb needed to land within about 10-15 feet of a surfaced submarine to cause lethal damage. Very difficult to do IRL.

So, OP, I'd assume that 75% of the "sub is reported HIT" messages are FOW. 25% are probably real. Most 500lb. (or 250kg bomb) "hits" (probably near misses IRL) will cause some pain requiring repair of the submarine. Rarely will you get an outright kill.

In order to increase the likelihood of a hit (or damaging near miss), trained bomber or patrol crews with an ASW rating of 70+ are advisable. Airframe weapon used is important too. A 500lb (or 250kg) bomb will do more damage than a 100kg (or 250lb) bomb, as you might imagine. Thus, select the best balance of airframe, range, ASW skill, altitude (<2000ft.) and co-ordination with other forces (ASW H/K groups, naval search, mines, etc.) for best effect.

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RE: ASW damage from AC - 2/5/2013 5:31:43 PM

John Lansford

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The problem of hitting a small half-submerged sub from a fast flying patrol plane was solved in mid-1943. Bombs on a B-24 patrol plane were fitted with forward facing rockets. When dropped, the rockets fired, countering the forward momentum of the bomb and allowing it to drop nearly vertically. The B-24 would drop three bombs with each attack, nearly insuring that the sub would be bracketed by the bombs and getting a hit.

I don't know if that innovation was ever put widely into use but it was invented and tried, apparently with some success in the Atlantic. I would think that rocket armed patrol planes were also more effective in damaging subs than just dropping bombs on them. After all, a hole in the sub's hull means it is no longer a submersible, and fairly easy to detect afterwards.

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RE: ASW damage from AC - 2/5/2013 5:42:27 PM

dr.hal

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One of the defenses of a sub IRL is early aircraft detection and thus time to dive quickly. So I would assume that the lower you search altitude the higher the probability of a hit or near miss. Given this I quite often put some ASW air assets on 100 Ft altitude at two or four hex range. But I've not played enough to confirm that this hypothesis is accurate or not. I would like to think that at 100 Ft the aircraft has a lot better chance of catching the sub still on the surface and thus improving its chances of success. But I'm not sure.

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RE: ASW damage from AC - 2/5/2013 7:21:56 PM

heibernt

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quote:

ORIGINAL: Chickenboy

So, OP, I'd assume that 75% of the "sub is reported HIT" messages are FOW. 25% are probably real. Most 500lb. (or 250kg bomb) "hits" (probably near misses IRL) will cause some pain requiring repair of the submarine. Rarely will you get an outright kill.

I put all my catalinas in Pearl on asw with a 7 max range on the second turn of a GC game. Now I got a ton of subsighting every turn and a report of around 5 hits every turn. If only 75% are fog, that means im hitting one sub every turn. That seems alot. I think my unexperienced pilots are overestimating there own marksmanship. Any specific reason you belive fog is 75% and not more? Even hitting a sub every 2nd turn seems alot..

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RE: ASW damage from AC - 2/5/2013 7:47:53 PM

Chickenboy

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quote:

ORIGINAL: heibernt

quote:

ORIGINAL: Chickenboy

So, OP, I'd assume that 75% of the "sub is reported HIT" messages are FOW. 25% are probably real. Most 500lb. (or 250kg bomb) "hits" (probably near misses IRL) will cause some pain requiring repair of the submarine. Rarely will you get an outright kill.

I put all my catalinas in Pearl on asw with a 7 max range on the second turn of a GC game. Now I got a ton of subsighting every turn and a report of around 5 hits every turn. If only 75% are fog, that means im hitting one sub every turn. That seems alot. I think my unexperienced pilots are overestimating there own marksmanship. Any specific reason you belive fog is 75% and not more? Even hitting a sub every 2nd turn seems alot..

I'm talking for good (70+ ASW skill) pilots. I've got no idea what reporting rate ASW scabs have, as I'd not waste my time in using them. These are rough estimates.

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RE: ASW damage from AC - 2/5/2013 10:27:38 PM

spence

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Of the 759 U-boats lost in WW2 250 were sunk by aircraft alone with another 37 sunk by a combination of both ships and aircraft. The larger part of the submarine losses attributable to aircraft occurred in 1943 and later. In addition to patrolling where the uboats actually constituted a threat the a/c drove the uboats down (underwater) where they often lost contact with the convoy. Thus merchant ship losses went down at the same time uboat losses went up.

IT SHOULD BE NOTED THAT ASSIGNING AIRCRAFT TO "FOLLOW CONVOYS" IS NOT POSSIBLE IN THIS GAME EXCEPT IN SO FAR AS A CONVOY STAYS WITHIN THE ASSIGNED ARC OF ASW.

In large part this was the result of two factors:

1) the Allies began to escort convoys with Very Long Range B-24s
2) the Allies began to heavily patrol the Bay of Biscay which was a "chokepoint" between the French bases of the uboats and the convoys.

According to Combined Fleet the IJN lost a lower percentage of submarines to aircraft. In part this may be because the I-boats patrolled much further from Allied airbase. A significant number of IJN sub losses resulted from SIGINT which allowed Allied subs to ambush the IJN as it sortied.

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RE: ASW damage from AC - 2/6/2013 11:25:25 PM

alanschu

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It's also possible that the hits are ones that only land close and cause maybe a few points of system damage.

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RE: ASW damage from AC - 2/7/2013 3:03:16 AM

crsutton

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I would guess that only about 10% of reported hits are actually hits. The rest are FOW.

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RE: ASW damage from AC - 2/7/2013 1:36:21 PM

John Lansford

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I wouldn't put ASW search planes at 100' altitude. They may get more hits but their search pattern will be very small, and the pilots' fatigue and crash rate will go way, way up really fast. If you want them to get the best hit chance, set them at 1000'. I set mine at 5000' and they find lots of subs and get a few hits. IMO it's more important to sight the subs than actually hit them from a plane; once they are spotted the ASW ships can jump on top of them fairly easily.

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RE: ASW damage from AC - 2/7/2013 3:46:55 PM

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John got a point; as long as the pilots are still rookies -70EXP it's better to use them to spot the subs, increasing therefore the DL and let some ASW skippers blow' em out or at least prevent them from attacking.

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RE: ASW damage from AC - 2/8/2013 7:41:02 PM

dr.hal

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quote:

ORIGINAL: John Lansford

I wouldn't put ASW search planes at 100' altitude. They may get more hits but their search pattern will be very small, and the pilots' fatigue and crash rate will go way, way up really fast. If you want them to get the best hit chance, set them at 1000'. I set mine at 5000' and they find lots of subs and get a few hits. IMO it's more important to sight the subs than actually hit them from a plane; once they are spotted the ASW ships can jump on top of them fairly easily.

John you are right, it does wear out the pilots. But there are things that you can do to mitigate that impact yet still get good results. If the squadron has 18 aircraft and about 22 pilots, put it on 50% ASW search at 100' and keep it close to shore... this would then become a sub no go zone. And it can be maintained almost indefinitely. I found this to be an excellent use of the Wirraways which I'm hard pressed to find another use for!

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RE: ASW damage from AC - 2/9/2013 1:40:17 AM

John Lansford

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Are the B-25D1's good ASW planes if you set them at 100'? Every time I assign them an anti-airbase mission they drop down and strafe anyway, so I'm wondering if they do that in ASW mode too.

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RE: ASW damage from AC - 2/9/2013 8:32:23 AM

inqistor

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It is worth to remember, that ANY training at 100ft will train Strafing. So even when whole groups is making ASW any percentage of training will NOT train ASW.

quote:

ORIGINAL: John Lansford

Are the B-25D1's good ASW planes if you set them at 100'? Every time I assign them an anti-airbase mission they drop down and strafe anyway, so I'm wondering if they do that in ASW mode too.

I do not think it is normal attack. According to Devs only ASW skill is used, so DB probably also do not make dive attack, and no plane is making skip-bombing.

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RE: ASW damage from AC - 2/9/2013 11:54:34 AM

spence

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Actual ASW AARs and attack photos by about 100 British, Canadian, and American a/c are to be found at:

http://www.uboatarchive.net/Uboatlist.htm

There exists a video of a PB4Y-1 attacking a U-boat (the quality of the video on my laptop is very poor - I think it has something to do with the settings on it since I saw it clearly on my old desktop). The a/c is at several thousand feet initially but drops down to 100 ft(-) to make the attack. In tis video and apparently routinely the machine gunners on the plane fired to suppress the flak. If one reads some of the "Reports of Interrogations of POWs" one finds that strafing by multiple .50 calibers inflicted significant damage on some of the uboats.

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RE: ASW damage from AC - 8/14/2013 1:12:20 PM

HexHead

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How about depth charges? Libs made great ASW platforms. Do the Allies get DCs for the air?

The primary result of air cover is forcing the sub down, though, even optimally.

< Message edited by HexHead -- 8/14/2013 1:13:49 PM >

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RE: ASW damage from AC - 8/14/2013 4:28:47 PM

Bullwinkle58

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quote:

ORIGINAL: heibernt

Thx for the reply. Yea i know i can only find out via the ship loss screen, but i was wondering what kind of typical dmg such an attack would cause. Will the sub still be operational, or does it have to return to port, or will it likely sink on the way home? Im just wondering so i might be better able to evaluate his sublosses, and thereby there presence in my shipping lanes.

In the game my limited experience has been a typical 500lb/250kg bomb strike on a sub will generate between 30 flooding and 95 flooding. In most cases system damage is in the 40-60 range. Some engine damage. There are many randoms involved. I do not recall an "off screen" sinking of a sub by air ASW in a first attack. Not saying they can't happen.

In every case it has happened to me I have needed to send the boat home to the yards. If flooding is over 70 and system in the range 40-60 there is an excellent chance it will not make it. If flooding is in the 50s with that system damage it has a fair chance if speed is reduced to Cruise.

In my experience that's the envelope more or less. Your results may vary.

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RE: ASW damage from AC - 8/14/2013 4:48:08 PM

Lokasenna

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I've had several I-boats sink from a single 500-lb bomb hit. They never made it more than 4-5 hexes away from where they got hit.

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RE: ASW damage from AC - 8/14/2013 4:54:46 PM

Bullwinkle58

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quote:

ORIGINAL: Lokasenna

I've had several I-boats sink from a single 500-lb bomb hit. They never made it more than 4-5 hexes away from where they got hit.

I've had USN fleet boats sink from it too. But after moving away, as you say. I've never had one sink in the attack hex, immediately. As before, not saying it can't happen.

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RE: ASW damage from AC - 8/14/2013 6:56:23 PM

AW1Steve

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quote:

ORIGINAL: Chickenboy

quote:

ORIGINAL: Lokasenna

In my IJ game against the allied AI, I've lost 2 subs to 500-lb. bombs off the west coast. In deep water, too. I have a better grasp of detection level mechanics and such now...

This came up in another thread recently. Usually, ASW aircraft aren't very effective at actually damaging subs. Where they succeed is in raising the DL. I see that ops report message all the time, but I figure that maybe only 1 in 50 actually represents a successful attack. Especially from Catalinas...though that could just be a result of their longer range. I believe the IJN subs that I lost to ASW aircraft were to SBDs.

If you actually manage to hit a sub with a 500-lb. bomb, it's hurting. Noticed that from the above losses as well as several port strikes in various games - one decent bomb hit typically results in boom/glug-glug.

I've lost a small handful of subs to Allied ASW air attack-Catalinas. 500 lb. bombs did the trick.

It's difficult in the game as it was IRL to get a sub kill with an aerial bomb. From Clay Blair's Hitler's U-Boat War (Volume 1): a 500lb. bomb needed to land within about 10-15 feet of a surfaced submarine to cause lethal damage. Very difficult to do IRL.

So, OP, I'd assume that 75% of the "sub is reported HIT" messages are FOW. 25% are probably real. Most 500lb. (or 250kg bomb) "hits" (probably near misses IRL) will cause some pain requiring repair of the submarine. Rarely will you get an outright kill.

In order to increase the likelihood of a hit (or damaging near miss), trained bomber or patrol crews with an ASW rating of 70+ are advisable. Airframe weapon used is important too. A 500lb (or 250kg) bomb will do more damage than a 100kg (or 250lb) bomb, as you might imagine. Thus, select the best balance of airframe, range, ASW skill, altitude (<2000ft.) and co-ordination with other forces (ASW H/K groups, naval search, mines, etc.) for best effect.

Andre , in fairness, Blair was discussing type VII and type IX U-boats. EXTREMELY tough boats. Much deeper diving then USN or IJN boats , and I'd bet tighter seems too. I was always taught that a depth charge within 30 feet would probably be a kill. And btw , depth charge is a misnomer. Any bomb fitted with a hydrostatic charge is a depth charge. (I recall discussing with a couple of ordancemen the possibility of fitting a 2000 pound mine with such a fuse. They winced and said "Yeah that'll leave a mark.")

If I recall, not only will machine gun and air cannon mess up a sub, the RAF was real big on using Mosquitos with rockets as sub killers in the Bay of Biscay. And on that subject , I recommend "Submarines and Slide Rules", a real egg head study on ASW in the Bay (Some of you math geeks will drool over the studies, me? They gave me a migraine.:()

I'd think the Moose will confirm that Shock is what kills subs , and opening the seems (and causing high pressure leaks) and not so much a direct hit.

My point is that I suspect the strength and condition of the boat has more to do with the kill of a sub then the size of the bomb or if it penetrates the hull. In that regard , aspect might be more important than explosion. A smaller bomb near the shaft seems or the torpedo seams might do more damage then one amidships. But I defer to the Moose. He's the subject matter expert.

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RE: ASW damage from AC - 8/14/2013 7:25:39 PM

Chickenboy

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Hi Steve,

My comments (Blair's quote) was on aerial bombs dropped on submarines per se. These didn't have hydrostatic fuses and-based on his comments-made comparatively inefficient submarine killers. Note the accuracy comment when using aerial bombs with instantaneous fuses.

Most of the Coastal Defense Liberators, Cats and other (mostly) British ASW air assets operating against the type VIIs, IXs and XIVs used depth charges-these were much more efficacious. Particularly after 1942, Coastal aerial ASW racked up ungodly numbers of u-boat kills. Usually while the boats were surfaced. Usually with a well-laid field of depth charges near the boat during an overflight. These DCs were 'shallow-set' to explode at 25-50ft. depth. Usually the low flying aircraft would clear the area before the blast, but premature detonations did occasionally fatal damage to the bombing aircraft. When combined with the standing 'stay and fight' orders and a rapid fire 37mm Flak gun, these sorties were not without risk.

Yeah, the Mossies in the Bay of Biscay operation were occasionally successful with rockets (or their 57mm 'stinger'), but the underappreciated killers were the B-24s and other heavy aircraft with multiple shallow-set DCs. A typical pass would see 4-6 dropped atop the submarine. A very bad day for the submariners with 4-6 shallow-set DCs erupting around you. The boats (as strongly built as they were) would splinter, hole and huge sections stave in.

Incompressible fluid hydrodynamics-fascinating stuff.

ETA: As far as the game goes, I'm OK with assuming that the ASW aircraft are using depth charges per se. With that in mind, I'm mostly comfortable with the implementation of aerial ASW, the damage wrought and expected progress of ASW capabilities.

ETAII: It would be cool if the game could mimic use of aerial ASW "Fidos" for the Allies or some of the special anti-escort homing torpedoes ("mines") used by the Allies very late in the war. Both were used in the war, with the former being credited with a number of U-boat kills. I don't see why they wouldn't work (even better) against slow-diving, poorly manuevering IJN submarines by USN Avengers.

< Message edited by Chickenboy -- 8/14/2013 7:35:33 PM >

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RE: ASW damage from AC - 8/15/2013 9:12:22 PM

Bullwinkle58

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quote:

ORIGINAL: AW1Steve

Andre , in fairness, Blair was discussing type VII and type IX U-boats. EXTREMELY tough boats. Much deeper diving then USN or IJN boats , and I'd bet tighter seems too. I was always taught that a depth charge within 30 feet would probably be a kill. And btw , depth charge is a misnomer. Any bomb fitted with a hydrostatic charge is a depth charge. (I recall discussing with a couple of ordancemen the possibility of fitting a 2000 pound mine with such a fuse. They winced and said "Yeah that'll leave a mark.")

If I recall, not only will machine gun and air cannon mess up a sub, the RAF was real big on using Mosquitos with rockets as sub killers in the Bay of Biscay. And on that subject , I recommend "Submarines and Slide Rules", a real egg head study on ASW in the Bay (Some of you math geeks will drool over the studies, me? They gave me a migraine.:()

I'd think the Moose will confirm that Shock is what kills subs , and opening the seems (and causing high pressure leaks) and not so much a direct hit.

My point is that I suspect the strength and condition of the boat has more to do with the kill of a sub then the size of the bomb or if it penetrates the hull. In that regard , aspect might be more important than explosion. A smaller bomb near the shaft seems or the torpedo seams might do more damage then one amidships. But I defer to the Moose. He's the subject matter expert.

I'm no expert for sure. I looked up some sites on underwater explosion physics and the maths are pretty deep. They are also highly dependent on a lot of factors not modeled in the game.

German boats were advertised as deeper-diving. The late-war fleet boats could and did go a lot deeper than speced. QA was also far superior, and fleet boats after the P-class ( I think) were 100% welded, not riveted. U-boats were cranked out in sections, sometimes by forced labor, and put together in a big hurry. I'd take my chances going to 700 feet on a Balao a lot quicker than a Type VII.

Also, you and I both know that training is worth a lot when it comes to casualties. USN submarines got stronger in that area across the war since by 1943 1/3 of every returning boat's crew was detached for new construction. The men got a rest which the U-boat crews did not, and every new unit was already seasoned when it left the yards. The U-boat force got more and more green as the war went on. Nothing beats a response to flooding like having done it before.

When DCs were invented their role was seen as a mission-kill weapon more than a vessel killer. Sonically blind the sub, cause depth excursions, start flooding, let the skimmers fly past. If the sub sank it was a bonus, but a mission kill would do. By mid-WWII killing the sub itself was of at least equal importance. The hedgehog and similar contact weapons reflected this mindset. Either dead or a miss. No damage.

Lethal range depended on a lot of factors as I said, but a hull which was contacted by the steam bubble from the DC explosion was probably going to tear. Punching holes through pressure hulls was almost impossible except by shaped charges. DCs depended on incompressibility of seawater and the bubble's energy to deform the hull enough to either open a seam, or most often shear off hull fittings or shake loose hull fittings inside the boat inboard of hull isolation valves. If that happens the boat has little choice but to go shallow to reduce flooding rate and pound in a DC plug and shore it to close the hole. Takes time, makes noise. If the shock wave sprung a hatch, a shaft seal, or a tube door those were even harder than pipe breaks. Hatches were doubled but a sprung shaft seal was often fatal. The ER in most subs exceeds reserve buoyancy in the pressure hull when its flooded.

Thirty feet might be a good number. But you have to remember that's only five Vikings'-worth.

And it's in 3D. A depth change is as good as an x,y change in getting over 30 feet of clearance. The steam bubble from the DC is roughly a sphere.

< Message edited by Bullwinkle58 -- 8/15/2013 9:16:29 PM >

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RE: ASW damage from AC - 8/16/2013 3:54:31 AM

crsutton

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quote:

ORIGINAL: Lokasenna

In my IJ game against the allied AI, I've lost 2 subs to 500-lb. bombs off the west coast. In deep water, too. I have a better grasp of detection level mechanics and such now...

This came up in another thread recently. Usually, ASW aircraft aren't very effective at actually damaging subs. Where they succeed is in raising the DL. I see that ops report message all the time, but I figure that maybe only 1 in 50 actually represents a successful attack. Especially from Catalinas...though that could just be a result of their longer range. I believe the IJN subs that I lost to ASW aircraft were to SBDs.

If you actually manage to hit a sub with a 500-lb. bomb, it's hurting. Noticed that from the above losses as well as several port strikes in various games - one decent bomb hit typically results in boom/glug-glug.

Hits are very rare in 1942 but it is not really the plane types so much as which ones carry search radar. That seems to increase the hit rate some. Most Allied naval attack aircraft have radar by 1944.

Numbers and experience count too. Viberpol had plenty of success with his planes vs me by training lots of Japanese pilots and saturating areas with patrolling aircraft. in 43 I would say that I had on average 20 subs either RTB or in the yard at any given time with damage from bomb hits. And a few sunk. A nuisance but not a game changer like the super E type ship was.

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RE: ASW damage from AC - 8/16/2013 4:24:59 AM

crsutton

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From: Maryland
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quote:

ORIGINAL: Bullwinkle58

quote:

ORIGINAL: heibernt

Thx for the reply. Yea i know i can only find out via the ship loss screen, but i was wondering what kind of typical dmg such an attack would cause. Will the sub still be operational, or does it have to return to port, or will it likely sink on the way home? Im just wondering so i might be better able to evaluate his sublosses, and thereby there presence in my shipping lanes.

In the game my limited experience has been a typical 500lb/250kg bomb strike on a sub will generate between 30 flooding and 95 flooding. In most cases system damage is in the 40-60 range. Some engine damage. There are many randoms involved. I do not recall an "off screen" sinking of a sub by air ASW in a first attack. Not saying they can't happen.

In every case it has happened to me I have needed to send the boat home to the yards. If flooding is over 70 and system in the range 40-60 there is an excellent chance it will not make it. If flooding is in the 50s with that system damage it has a fair chance if speed is reduced to Cruise.

In my experience that's the envelope more or less. Your results may vary.

Yes, it a different story for Allies subs-even the small ones. A single bomb hit will never put one under, and most Japanese ASW planes have fairly small bombs so some hits do not even put the sub out of action. It takes multiple hits (rare) to sink an Allied sub. I had a lot of damaged subs heading home but Japanese air attacks were never a real threat.

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(in reply to Bullwinkle58)

Post #: 27

RE: ASW damage from AC - 8/18/2013 5:53:13 PM

sandman455

Posts: 209
Joined: 7/5/2011
From: 20 yrs ago - SDO -> med down, w/BC glasses on
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quote:

ORIGINAL: Bullwinkle58
Thirty feet might be a good number. But you have to remember that's only five Vikings'-worth. And it's in 3D. A depth change is as good as an x,y change in getting over 30 feet of clearance. The steam bubble from the DC is roughly a sphere.

My memory is rapidly fading but here is what I recall for single drop @ periscope depth for hull compromise -

15 kt nuke - sorry but you would be shocked and the numbers that follow would make a lot more sense
2000lb GP bomb (50% HE) 18-25'
500lb GP bomb 8-12'
100lb GP bomb 4-6'
1-99lb GP bomb 1-2'

Surface numbers would be about the same since the fuse would still put the weapon at the same depth. BTW, if you hit the target while its on the surface you'll probably get a hull breach with any bomb but should the fuse fail the sub will still have a decent shot at sailing home with a great sea story about how it blew you out of the air.

quote:

ORIGINAL: AW1Steve
If I recall, not only will machine gun and air cannon mess up a sub, the RAF was real big on using Mosquitos with rockets as sub killers in the Bay of Biscay.

Subs were pretty immune to light weapons. They would tear up the outer hull and fixtures but that's about it, no hull compromise. To get a decent chance at real damage you would need a 40-57mm gun and some steep angle hits less your rounds deflect off the outer hull or water. Since most patrol craft can't dive worth a crap, you are looking at rockets or bombs. Ships needed a 4" or better to have some good chance of success at penetrating water/hull or overcoming the high angle deflection angle.

quote:

ORIGINAL: Bullwinkle58
I'd take my chances going to 700 feet on a Balao a lot quicker than a Type VII.

Hell no. A WW2 Balao at 700' - you sir are as close to dead as can be. Please don't reference the Chopper - it was a Guppy, far removed from it's WW2 configuration and it never sustained the depth. Wasn't even on an even keel which makes the depth readings unreliable. When she surfaced, she was so overstressed she had to be scrapped. For any type VII or IX uboat, 700' was a walk in the park - documented countless times. A depth of 900-1000' would have been approx crush depth for most of them if you had the guts to go there. A few did and IIRC they were still serviceable afterwards.

quote:

ORIGINAL: Chickenboy
ETAII: It would be cool if the game could mimic use of aerial ASW "Fidos" for the Allies or some of the special anti-escort homing torpedoes ("mines") used by the Allies very late in the war. Both were used in the war, with the former being credited with a number of U-boat kills. I don't see why they wouldn't work (even better) against slow-diving, poorly manuevering IJN submarines by USN Avengers.

FIDO - it was kind of like a quick use mine. It homed in on noise - if I remember it was the band at which the diesel engines fuel injectors worked. Without that diesel running your weapon was worthless. It was the weapon of choice for a snorkled sub or any at night. Trying to hit a target with so little to aim at was pretty hard. Half the time you couldn't see the sub/snorkle in time to make a good drop. Any close aboard fly over could easily alert the sub ruining any chance of setting up again. This thing allowed the aircraft to pickle the weapon on the initial flyover or well ahead to remain unnoticed. Again, the weapon was going to be worthless if the enemy figured out how it worked.

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VS27 1990-91 (NATOPS/Safety)
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(in reply to Bullwinkle58)

Post #: 28

RE: ASW damage from AC - 8/18/2013 6:37:47 PM

witpqs

Posts: 26087
Joined: 10/4/2004
From: Argleton
Status: offline

quote:

ORIGINAL: sandman455

quote:

ORIGINAL: Bullwinkle58
Thirty feet might be a good number. But you have to remember that's only five Vikings'-worth. And it's in 3D. A depth change is as good as an x,y change in getting over 30 feet of clearance. The steam bubble from the DC is roughly a sphere.

My memory is rapidly fading but here is what I recall for single drop @ periscope depth for hull compromise -

15 kt nuke - sorry but you would be shocked and the numbers that follow would make a lot more sense
2000lb GP bomb (50% HE) 18-25'
500lb GP bomb 8-12'
100lb GP bomb 4-6'
1-99lb GP bomb 1-2'

Surface numbers would be about the same since the fuse would still put the weapon at the same depth. BTW, if you hit the target while its on the surface you'll probably get a hull breach with any bomb but should the fuse fail the sub will still have a decent shot at sailing home with a great sea story about how it blew you out of the air.

So what does "sorry but you would be shocked" equal in numbers?

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Post #: 29

RE: ASW damage from AC - 8/18/2013 6:40:13 PM

Chickenboy

Posts: 24520
Joined: 6/29/2002
From: San Antonio, TX
Status: offline

quote:

ORIGINAL: sandman455
FIDO - it was kind of like a quick use mine. It homed in on noise - if I remember it was the band at which the diesel engines fuel injectors worked. Without that diesel running your weapon was worthless. It was the weapon of choice for a snorkled sub or any at night. Trying to hit a target with so little to aim at was pretty hard. Half the time you couldn't see the sub/snorkle in time to make a good drop. Any close aboard fly over could easily alert the sub ruining any chance of setting up again. This thing allowed the aircraft to pickle the weapon on the initial flyover or well ahead to remain unnoticed. Again, the weapon was going to be worthless if the enemy figured out how it worked.

This is contrary to the useage of the FIDO weapon system used against the U-boats, according to Blair.

The weapon was typically dropped by Avenger-type aircraft after the U-boat had submerged.
The attacks typically took place by daylight scout aircraft-often a pair of F4F and TBF/M. The F4F would strafe the submarine, forcing it to submerge. The Avenger would come in and drop on the swirl. Daylight attack, submerged U-boat.

The U-boats weren't using their diesels after submerging. Therefore, the guidance system of the FIDO was unlikely to be the diesel pressurization system.

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Post #: 30