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jugent
03-15-2005, 01:48 PM
According to umpire manual for US-Army 1944 the loss prohabilty for 3" AA-battery 4 guns, on a formation of 8 figter A/C (Single engine?) is 1/16 during a 30sek kontinuing fire at 5000m. Above that is not declared. This is supposed to be from a solid gunplatform and fuses set corrctly.
Take a check at all details and correct me.

http://www.hardscrabblefarm.com/ww2/umpire_manual.htm

jugent
03-15-2005, 01:48 PM
According to umpire manual for US-Army 1944 the loss prohabilty for 3" AA-battery 4 guns, on a formation of 8 figter A/C (Single engine?) is 1/16 during a 30sek kontinuing fire at 5000m. Above that is not declared. This is supposed to be from a solid gunplatform and fuses set corrctly.
Take a check at all details and correct me.

http://www.hardscrabblefarm.com/ww2/umpire_manual.htm

horseback
03-15-2005, 01:59 PM
Is that with or without proximity fusing?

Gee do ya think the AAA in FB/PF is overmodelled, by any chance?

cheers

horseback

jugent
03-15-2005, 04:02 PM
As far as I know they used a clockwork fuse at the beginning, and developed the proximity fuse for large caliber guns 90mm? and used it in 1944 in the pacific and against V1 bombs in England. They where terrified that the germans would copy it and use it against the allied bomber-armada. This umpire manual is from 1944 so it can be a proximity fuse, and in that case, the figures for clockwork fuse would be much worse.
Yes I think it is suicide and almost impossible to attack a CV, and it doesnt seems to matter if you fly with 10 attackers or 1, the prohability to be killed the same. But I dont have any stastic calculation in that matter.

AlmightyTallest
03-15-2005, 08:12 PM
Here's an article about U.S. naval 5 inch Radio Fused ammunition as used in WW2. May help answer some questions, it's a really interesting read and below are some quotes I found interesting.

http://www.smecc.org/radio_proximity_fuzes.htm

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>On January 29, 1942, a group of fuzes with miniaturized components and dry cell batteries, built on a pilot production line, were installed in standard 5-inch anti-aircraft projectiles and fired from a 5-inch 38-caliber anti-aircraft gun. At the end of a 5-mile trajectory 52 percent had successfully activated themselves by proximity to water. Although this appeared to be a low percentage, the protection given by these shells was far greater than that achieved by saturation shelling. The Bureau directed the Crosley Corp. to commence pilot production of the fuzes without delay. The name that was assigned was the €˜VT Fuze€, with the VT standing for variable time <HR></BLOCKQUOTE>



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> On August 12, 1942, the first pre-combat service tests were made by the newly commissioned U.S.S. Cleveland. The commander, Capt. S. E. Burroughs, USN, had the ship on a shake down cruise in the Chesapeake Bay. Radio controlled planes (drones) were used as targets. The Gunnery Officer, Lt. Commander. Russell Smith, USN, was an experienced fire-control officer. His gun crews consisted of approximately 10-percent experienced personnel and the remainder were newly enlisted. Smith, with his nucleus of experienced personnel, worked hard before and during the shakedown period to train his fire control and gun crews and achieved magnificent results. The tests were scheduled for a period of 2 days and were to be conducted under simulated battle conditions. All three available drones were destroyed early on the first day while going though all possible evasive maneuvers, by the bursts of only four proximity fuzed projectiles. This was an amazing event to all who witnessed it! Here was a device which would force enemy aviators to be more respectful! <HR></BLOCKQUOTE>

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> In the middle of November 1942, 5,000 rounds of proximity-fuzed projectiles in storage at Mare Island were rushed to Noumea for distribution to ships of a task force in the southwest Pacific. The first ship to introduce them to the enemy was the U.S.S. Helena. On January 5, 1943, four Japanese bombers attacked the task force and the Helena downed one with the second salvo of proximity-fuzed ammunition <HR></BLOCKQUOTE>

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> Realizing that the details of the fuze must be kept from the enemy, the Combined Chiefs of Staff issued a ban against its use in any area where duds or live shells might be recovered by the enemy. During World War II, the Japanese were famous for being able to copy captured radar equipment, and the Americans did not wish this fuze copied and used against the allied forces. This restricted the fuze€s usage to naval warfare and also prevented it from being used in naval shore bombardment of enemy-held territories. <HR></BLOCKQUOTE>

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> During 1943 approximately 9,100 rounds of proximity-fuzed and 27,200 rounds of time-fuzed 5-inch anti-aircraft projectiles were fired. Fifty-one percent of the hits on enemy planes were credited to VT-fuzed projectiles. The proximity Fuze equipped shells success in repelling air attacks against fleet units reached its peak when a task group in the Pacific reported the destruction of 91 of 130 attacking Japanese planes. This high level of effectiveness was to save many servicemen€s lives from the onslaught of Kamikaze attackers. Had not these Samurai minded pilots been removed from the air, they would have rammed their planes onto the decks of our navy vessels causing the death of many servicemen. The VT Fuzed shells were also used with great success in the Mediterranean and Atlantic theaters.
<HR></BLOCKQUOTE>

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>"It was the sort of test that would never be allowed today under the prevailing flight safety guidelines. At the time, however, there was a war on, and the small risk to our one aircraft had to be weighed against the far larger risk to our whole bomber force if the Germans used such a weapon against us. We who were to fly the test were confident we would be all right - we hoped that the jamming would work as planned, and if it didn€t, the offset fed into the guns would burst the shells at least 240 feet away from us at a range of about 20,000 feet."

"The test lasted about 3 months, during which about 1,600 VT shells were fired, individually, in our direction. Sitting in the fuselage of the B-17, the two RCM operators could pick up the radar transmissions from the shells coming up. The VT fuse radiated CW (continuous wave) signals, but the projectiles would often yaw a little in flight. This, in combination with the spin of the shell, would modulate the signal. We in the back could not see out, but the pilots and the navigator would get a kick out of watching the shells burst well below, or if there was a late burst because the jamming had taken some time to sweep through the shell€s frequency, it might explode close to our altitude. The general conclusion of the test was that, modified to radiate CW swept across the VT fuse band, the APT-4 jamming could significantly reduce the effectiveness of the proximity fused AA shell."
<HR></BLOCKQUOTE>

jugent
03-16-2005, 03:49 AM
Thanks for the article. I assume that this umpire manual must be of conventional clockwork fuse.
I am impressed that a radiotube radar could withstand the acceleration, and rotation inside a shell.

AlmightyTallest
03-16-2005, 09:07 AM
I'm impressed as well. I didn't quote everything from that article, there is a section about the 90mm guns firing these special shells. My metric isn't good so I'm guessing that 90mm is 3 inches?

At any rate, these devices were one of the secret weapons of the U.S. They turned what would be misses or near misses by conventional shells into hits.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>During 1944 the intense warfare in the European theater of operations necessitated the lifting of the ban against the use of the fuze where it might be recovered by an enemy. On 12 June 1944 the first V-1 "buzz bomb" fell on London marking the start of Hitler€s massive effort to level the city by rocket. The all-out valiant effort of the Royal Air Force was not able to devise a good defense against this new weapon.

The Combined Chiefs of Staff reluctantly agreed upon the necessity of using the proximity fuze in the defense of London. Large numbers of anti-aircraft guns were moved to the channel coast where they could fire at the bombs over water. Success in destroying the V-1 rocket bombs by gunfire increased proportionally with the increase in the use of VT-fuzed projectiles. In the last month of the terrifying 80 days, 79 percent of the bombs engaged were destroyed as compared with the 24 percent destroyed during the first week of the attacks. On the last day of large-scale attacks only 4 Of 104 bombs succeeded in reaching their target. Some of the 100 destroyed are credited to the Royal Air Force and to the barrage balloons, but the majority of the V-1€s were victims of proximity-fuzed projectiles. There was little profit to the enemy with such a small percentage of success so Hitler turned the weapon on the port of Antwerp, which at that time was vital to the Allied supply lines. In the autumn of 1944 the devastating damage wrought while the Allies were redeploying anti-aircraft guns threatened to close the port. As the number of guns firing the proximity fuze increased, the damage decreased and the Allies were able to move their guns closer and to assume the offensive against the aerial targets. The defense of Antwerp resulted in the Combined Chiefs of Staff removing all bans against the use of the fuze which was most fortunate for the allied soldiers fighting there.

In late December 1944, von Rundstedt launched a counterattack which developed into the Battle of the Bulge. The use of the fuzes entered a new field, that of artillery fire against ground forces. The results of this usage was devastating to German troops and put fear into their hearts. No longer were their foxholes heavens against shrapnel burst, for with the use of the "funny fuze," as it was termed by General Patton, the shrapnel bursts occurred before the projectiles hit the earth, and high-velocity fragments rained down on the German attackers!
<HR></BLOCKQUOTE>

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> A move to develop countermeasures against proximity fuzes stemmed from the Germans, who during the "Battle of the Bulge," captured an Army munitions dump that contained a large number of the new radar proximity-fused shells. Concerned that the Germans might attempt to copy the proximity fuze, the Research Division of the Aircraft Radio Laboratory at Wright Field, along with the help of the RLL, was called in begin the development of jamming equipment. Lieutenant Jack Bowers, an engineer with the Aircraft Radio Laboratory at Wright Field, recounted the following to Alfred Price:

"The proximity fuse had been a closely guarded secret on our side. Even though we had been working on countermeasures for a long time, we at Wright Field had never heard of the device. Now we were asked to investigate, on a crash basis, the possibility of a jammer to counter the fuse. We asked why such a jammer had not been developed earlier, and were told that the developing agency had conducted tests and concluded that the fuse could not be jammed! We worked on the problem, and within two weeks, a jammer had been built which would detonate the proximity fuses prematurely."

Since the body of the shell served as the antenna for the radar proximity fuse, it limited the frequency spread of the transceiver from 180 to 220 MHz. The APT-4, a high powered jammer, already covered that part of the spectrum. A motor-driven tuner was added to sweep the jamming transmitter€s signal up and down the band theoretically covered by the fuze. Several modified APT-4€s were installed in a B-17, and a top priority full scale test was arranged at Eglin to see whether the countermeasures would be effective.

Price, in another interview with Lieutenant Ingwald Haugen, one of people involved with the test, Haugen tells him:

"For the firing test, the Army sent a battery of 90 mm anti-aircraft guns. These were emplaced near Eglin. We had requested that during the test the guns would fire VT (proximity fused) shells with spotting charges, so that when the fuses operated, the shells would burst with only a puff of smoke. We were told this was not possible. The VT fuse was about 1 1/2 inches longer than the normal mechanical fuse and it would not fit in a shell carrying a spotting charge. So, we were going to have to use live high explosive VT fused shells for the test. As a safety measure, the guns were to be offset by a small angle, initially 30 mils (about 1.7 degrees), later decreased to 12 mils (about .6 Degrees)."

<HR></BLOCKQUOTE>

jugent
03-16-2005, 09:31 AM
A inch is according to my figures 25.4mm gives 76.2 the same calibre as early russian anti-tank guns.
I dont know if they got proximity fuse on such small calibres.