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#21
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In message
, Geoffrey Sinclair writes snip Method 3: making the shell body part of a resonant circuit and detecting frequency changes. Should be fun lugging the fused shells around metal guns. IIRC the fuse was inactive until fired. The shock of firing broke a glass cell containing the battery acid, the battery then produced the required voltage. Mike -- M.J.Powell |
#22
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Eunometic wrote: You'll find that there were at least two other allied photoelectric based fuses. The first one entered service on rockets (it couldn't handle the shock of a gun launch) but its photocells found application in the punched paper tape reader of the colossus machine used in decrypting Enigma. The second system could withstand a cannon lauch and entered service. It used a torrodial perspex lens around the circumference or rim of the shell that focused on a photocell. To be fair most of these German fuses were for different purposes than cannon shell launch. Missiles need more sophisticated and jam resistent radio proximity fuses. In addition the Germans were clearly hedging their bets by developing a spread of systems to reduce their exposure to Allied Jamming attempts. The German were big investors in both passive and active infrared technology and this was begining to pay of in 1945. In part the plethora of projects represents the secrecy compartmentalisation, as well as intersevice rivalries but also a policy of phased development was in place so that the Germans could catch up and stay ahead in areas such as radar. In reality relying on one proximity fuze type is a recipe for disaster. The allies relied on secrecy and then the hope that the Germans couldn't react in time. The Wasserfall and Enzian Surface to Air missiles for instance had a spread of guidence and proximity fuze systems under development. Wasserfall had a 3 axis gyroscopic version of the two axis gyroscopic guidence system in the V2 including apparently the PIGA accelerometer. Even without external guidence it would have placed itself within a few hundred meters of its target. There an infrared terminal homing system was to be used (Madrid), or alternatively command guidence using a radar called "Mannheim" (80 of these track-lock entered service) or visual command guidence. There was also a semi active guidence system under development called "Moritz". The command link was based on a specially developed version of the "Khel/Strassbourg" system used on Fritiz-X and Hs 293 but also on a purpose built system called "Kogge/Brigge" SNIP See the US guided and glider bomb programs for a similar list of proposed and experimented with guidance systems (VB/BG series) Fletcher BG-1 After the USAAF had cancelled the order for the Fletcher PQ-11A radio-controlled target drone, ten of the PQ-11As under construction were completed as XBG-1 bomb gliders. In the XBG-1, the PQ-11A's engine was replaced by a 900 kg (2000 lb) bomb. The XBG-1 was to be towed to the target area by a larger aircraft and upon release was to be guided to target impact by radio-commands using imagery transmitted from a TV camera in the glider's nose. No information on the XBG-1 test program is available, but the model was never used operationally. Fletcher BG-2 When the Frankfort CG-1 troop-carrying glider was cancelled in 1941, the three XCG-1s under construction were completed by Fletcher as XBG-2 bomb gliders. No information about the bomb load or the results of tests (if any!) is available, but the BG-2 program was cancelled in 1942. Cornelius BG-3 The BG-3 was a design with nose-mounted horizontal stabilizers and forward-swept wings. As such it was possibly similar to Cornelius' XFG-1 fuel glider. Although the USAAF had planned to procure one XBG-3 prototype, this order was cancelled in 1942 The VB designation was introduced by the U.S. Army Air Force in 1943, and covered unpowered guided bombs with effectively no standoff gliding range (i.e. "vertical" bombs). ATSC VB-1/VB-2 Azon In April 1942, the USAAF's Materiel Command (became part of ATSC (Air Technical Service Command) in 1944) began the development of the Azon family of guided bombs. The initial variant, designated VB-1, was based on a 450 kg (1000 lb) bomb (initially the M44, but later models apparently switched to the standard AN-M65), which was modified with a new tail unit. The latter consisted of a gyroscopic unit to provent the bomb from rolling, a flare for optical tracking, an octagonal shroud with control surfaces, and a radio-command receiver. When a VB-1 was dropped, the bombardier could track it through his bombsight and use a joystick-type control to send corrective commands to the bomb. The Azon guidance system allowed only lateral course corrections, but errors in range could not be corrected (hence the name Azon = "Azimuth Only"). The Azon development phase ended in late 1943, and the VB-1 was subsequently ordered into mass production. The second Azon variant was the heavier VB-2, which was based on a 900 kg (2000 lb) bomb, but that version was apparently not produced in very large numbers. The first VB-1/2 bombs were sent to Europe in February 1944, and a total of 15000 Azons were produced until November 1944. Because of their azimuth-only guidance, the VB-1 was particularly suited to long and narrow targets (like bridges or railways) where range errors would be irrelevant. For "normal" targets, however, the VB-1 was actually not as good as unguided free-fall bombs, because a bomber could not break away immediately after dropping the bomb, and the accuracy was effectively not increased because of the lack of range control. Another peculiarity of the Azon guidance set was the fact that only five different radio channels were available for the command link, meaning that not more than five bombs could be controlled independently. Although in theory a whole group of bombs using the same command channel could be controlled simultaneously, this was not practical. The accuracy of all but the "primary" bomb (i.e. the one which was tracked by the bombardier) in such a group was rather bad, because the non-spinning Azon bombs showed a significant dispersion. The drawbacks of the Azon meant that its use remained very limited. However, it was employed rather successfully in Burma, where it was used to destroy very vital and therefore heavily defended bridges along the Japanese supply lines. Less the 500 Azons were needed to destroy 27 bridges. When the war ended, the USAAF quickly removed the VB-1 and VB-2 from its inventory. Because of the much reduced post-war funding, the USAAF limited its guided vertical bomb research to the more advanced VB-3/VB-4 Razon family. ATSC VB-3/VB-4 Razon In parallel with the Azon tests, the ATSC also developed a more advanced variant called Razon, which was to be controllable in both range and azimuth. The designations VB-3 and VB-4 were assigned to the 450 kg (1000 lb) and 900 kg (2000 lb) Razon versions, respectively. The Razon guidance kit had two octagonal shrouds in a tandem arrangement. The most problematic part in Razon development was to build a suitably modified bombsight, which would allow the bombardier to correctly judge the bomb's deviation in range so that the range control could be used effectively. The Razon also had an improved radio-command link with 47 separate channels, effectively eliminating the Azon's problems with concurrent drops by a multitude of bombers. The VB-3/VB-4 was combat-ready in summer 1945, and about 3000 Razons were subsequently produced, but none of them were used before World War II was over. However, the VB-3 was operationally tested five years later during the first months of the Korean War. B-29 aircraft, which could carry eight VB-3s, dropped several hundred Razons on North Korean bridges, and although the overall reliability of the bombs was rather low, some targets were actually destroyed. However, in general multiple hits by the small the 450 kg (1000 lb) bombs were needed to destroy a large bridge span, and the USAF's use of guided bombs for these special missions switched to the much larger VB-13/ASM-A-1 Tarzon. ATSC VB-5 The VB-5 was a 450 kg (1000 lb) bomb, which used the same tandem octagonal control shroud arrangement as the VB-3/VB-4 Razon. However, the VB-5 was not command guided but used an autonomous light contrast seeker. This bomb did not go into production, presumably because the guidance mechanism didn't work as planned. ATSC VB-6 Felix The VB-6 Felix was a 450 kg (1000 lb) bomb with an octagonal control shroud and a heat seeking device in the nose. Intended for use against strong infrared emitters (like e.g. blast furnaces), the VB-6 was tested with some success during 1945, but the program was cancelled at the end of World War II. The U.S. Navy developed a very similar IR-guided bomb as the ASM-N-4 Dove. ATSC VB-7, VB-8 The VB-7 and VB-8 both used a TV/radio-command guidance, where a TV camera in the bomb's nose transmitted the image to a display set for the bombardier, who could then correct the bomb's course by radio-commands. The weights of the VB-7/VB-8 are unclear, but it can be assumed that these two guided bombs were cancelled early in the development phase. Douglas VB-9/VB-10/VB-11/VB-12 Roc The Roc series of guided bombs was developed by Douglas, the MIT and the NDRC (National Defense Research Committee). The VB-9 model was a 450 kg (1000 lb) bomb with cruciform wings and fins and a radar seeker in the nose. The radar image was transmitted to the bombardier who could use it to direct the bomb's path by radio commands. However, the radar was often useless because of ground clutter, and the VB-9 program was terminated in early 1945. VB-9 The later Roc models all used a 450 kg (1000 lb) bomb body of 61 cm (24 in) diameter and 3 m (10 ft) length. They were fitted with two circular shrouds, a larger one which could move around two axes for directional steering, and a smaller one in the tail designed to slow down the bomb to facilitate the tracking and guidance task of the bombardier. The VB-10 had a TV camera and transmitter, so that the bombardier could track the bomb via the image on his TV display set. The VB-11 had an infrared seeker for autonomous heat-seeking guidance, and the VB-12 was tracked visually (making it similar in operation to the VB-3/VB-4 Razon). VB-10/11/12 The VB-10 (and presumably also the VB-11/VB-12 models) was tested between September 1944 and May 1945, when the Roc program was terminated without any model going into production. Bell VB-13 Tarzon The VB-13 is discussed on a separate page about the VB-13/ASM-A-1 Tarzon. Specifications The few available data on the dimensions and weights of the VB-series bombs are mentioned in the main text http://www.designation-systems.net/d...pp1/index.html http://www.wpafb.af.mil/museum/arm/vb.htm The smaller Ruhrstahl X-4 wire guided Air to Air missile opperated with basic wire guidence and a contact fuse backed up accoustic proximity fuse called "Kranich". A accoustic terminal homing system "Dogge" was also under development as was an infrared terminal homing system and proxitmity fuse. The same systems were planed for the Enzian missile including an accoustic homing head called "Archimedes" The accoustic homing systems worked quite well. A Me 262 Jet equiped with accoustic homing systems could detect a bomber and its directions to about 4-5 miles range. SNIP I'm sorry, but I find an acoustic system that sensitive, yet able to filter out the wind noise of going 500 mph, along with the howl of two turbojets a bit hard to believe. Could you provide more details or a citation? |
#23
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Eunometic wrote:
The German proximity fuse. Not exactly an article for this newsgroup. We strive to remain on topic and would appreciate if posters would keep this in mind. |
#24
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"Jim" wrote in message ... Eunometic wrote: The German proximity fuse. Not exactly an article for this newsgroup. We strive to remain on topic and would appreciate if posters would keep this in mind. I did not realize that naval aircraft were immune to anti-aircraft fire...be so be it. Tex |
#25
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"Jim" wrote in message ... Eunometic wrote: The German proximity fuse. Not exactly an article for this newsgroup. We strive to remain on topic and would appreciate if posters would keep this in mind. Incorrect, this is one of the rew recent threads that IS on topic. As an example the use of proximity fuses was critical to defending the USN against kamikaze attack in WW2 Keith |
#26
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Keith W wrote:
"Jim" wrote in message ... Eunometic wrote: The German proximity fuse. Not exactly an article for this newsgroup. We strive to remain on topic and would appreciate if posters would keep this in mind. Incorrect, this is one of the rew recent threads that IS on topic. As an example the use of proximity fuses was critical to defending the USN against kamikaze attack in WW2 Keith Our group is NAVAL AVIATION. CHARTER: rec.aviation.military.naval The purpose of this newsgroup is to facilitate open discussion about all issues relating to Naval Aviation. It will provide a global forum for: - pilots - naval flight officers - flight crew members - aircraft maintenance personnel - air traffic controllers - flight deck personnel - other support personnel - others interested in Naval Aviation The discussions will be based upon: - flight training - squadron history - aircraft carrier operations - patrol missions - lighter-than-air operations - combat experiences - tower/GCA/CATCC experiences - other subjects relating to and about Naval Aviation The goal of these discussions is to provide a global community access to discuss issues relating to Naval Aviation and foster interest in others regarding this unique aspect of aviation. A FAQ file(s) will be developed to include discussion topics outlined above and other issues that will arise from the operation of the newsgroup. The newsgroup will be unmoderated. Commercial postings are not welcome as the group as proposed does not require Vendors or Suppliers. Binary file or graphic productions are prohibited. However a posting may include reference to a URL or FTP pointing to such binary files. |
#27
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M. J. Powell wrote: In message , Geoffrey Sinclair writes snip Method 3: making the shell body part of a resonant circuit and detecting frequency changes. Should be fun lugging the fused shells around metal guns. IIRC the fuse was inactive until fired. The shock of firing broke a glass cell containing the battery acid, the battery then produced the required voltage. The initial fuses that entered service used a 'normal' battery. It worked quite well however the batteries would degrade in only a few months hence the above batteries were developed. Nose mounted wind turbine driven generators were also used in experimental shells but were rejected, probably for cost reasons. The German electrostatic influence fuse used a battery. I don't know what battery technology they used. Mike -- M.J.Powell |
#28
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"M. J. Powell" wrote:
In message , Geoffrey Sinclair writes snip Method 3: making the shell body part of a resonant circuit and detecting frequency changes. Should be fun lugging the fused shells around metal guns. IIRC the fuse was inactive until fired. The shock of firing broke a glass cell containing the battery acid, the battery then produced the required voltage. Mike Jesus...I'd hate to be the second guy to accidentally drop the damned thing... -- -Gord. Keep in mind that I'm an expert with questions, so if you have any, fire away. Be aware however, that answers quite often give me trouble. |
#29
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Jim wrote:
Keith W wrote: "Jim" wrote in message ... Eunometic wrote: The German proximity fuse. Not exactly an article for this newsgroup. We strive to remain on topic and would appreciate if posters would keep this in mind. Incorrect, this is one of the rew recent threads that IS on topic. As an example the use of proximity fuses was critical to defending the USN against kamikaze attack in WW2 Keith Our group is NAVAL AVIATION. CHARTER: rec.aviation.military.naval The purpose of this newsgroup is to facilitate open discussion about all issues relating to Naval Aviation. snip Don't be silly Jim...how close to aviation do you want?...sure beats that political crap that we see occasionally... -- -Gord. Keep in mind that I'm an expert with questions, so if you have any, fire away. Be aware however, that answers quite often give me trouble. |
#30
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Eunometic wrote in message . com...
Geoffrey Sinclair wrote: Eunometic wrote The German proximity fuse. The development of the US proximity fuse by the US in WW Two is regarded as a unique allied triumph. Little known however is that the Germans independently developed and successfully test fired almost 1000 rounds of a similar proximity fuse near the wars end that if introduced into service would have had a dramatic effect. The allies estimated that the availability of the proximity fuse would force them to abandon use of the B-24 Liberator due to its lower flying altitude compared to the B-17. The B-24 made up around 1/3 of the 8th Air Force and 2/3 of the 15th Air force, all up just under half the USAAF bombers. The main deployment of B-24s to Europe was in 1944. It was a USAAF estimate, flak losses would triple, bombing heights would have to increase and the B-24 not used against well defended targets. When the German flak concentration around the main synthetic oil plants became so great the USAAF started to use cloudy days, relying on radar aids, assuming the loss of accuracy for the gunners was greater than that of the bombers. Not flak losses were never above the critical loss rates, but would have approached it if they were tripled. It took fighters to really cut up a bomber formation. What were the critical levels? 10% losses would mean a 65% loss after only 10 missions. 3% sounds sustainable. Overall according to the USAAF statistical digest the 8th Air force flew 1,034,052 heavy bomber sorties, 898,758 considered effective, losing 2,439 to flak. So between a 0.23 and 0.27% loss rate. The RAF considered 5% loss rates unsustainable long term and the USAAF seems to have agreed. The Allied Proximity fuse was used on both Anti-Aircraft Artillery and anti-personnel howitzers where they were set to explode approximately 50 feet above the ground. At that height they would produce a lethal zone over a terrifyingly wide area. When used against aircraft it seemed to increase effectiveness of a round by 3-7 or more. So the 16,000 88mm shells per shoot down fired would be reduced to 2,300 to 5,300. The Germans did better early in the war in terms of shells per aircraft but this was the sort of price paid for using effectively reserve manpower in the flak units alongside less accurate fire control systems. I suspect that the use of the proximity fuse would place pressure on increasing accuracy. I suspect that barrels were not renewed as often as was optimal. Alternatively the proximity fuse could reduce the pressure for new guns, so the savings could be used elsewhere. The flak service needed to replace an average of 380 88mm guns a month in 1944, thanks to wear or destruction. Even in 1942 it was 148 guns a month. Increasing accuracy is firstly a function of the fire control systems, something the Germans struggled to provide. Then go for barrel wear and ammunition quality. The 128mm FLAK gun had a fuse setter installed on the barrel to allow the fuse time to be set while the round was in the barrel. This was so the time fuses could be set at the last possible moment, eliminating the differences in time taken between setting the fuse then manually loading and firing the shell. The time tended to go up as the crew tired. It is my understanding that most 88 guns had an external fuse setting device that was a box next to the barrel. So the FLAK crew (9 men or children) would neet to maintain a rhythm of following the dials and pointing the gun, inseting the round in the fuse setter removing it inserting the round in the barrel etc. Putting servo drives on the gun and in barrel fuse setters would I suspect also have increased accuracy. The problem is that there isn't enough skilled labour to build, calibrate,maintain this equipement. Then add the shortage of radars to provide accurate range information, in particular height. (snip) As has been stated the last time this information was posted, The claim ignores the USS Helena firing proximity fused shells off Guadalcanal in January 1943. Fuse production was 500 per day in October 1942. Note by the end of 1944 the delivery rate was 40,000 per day, or in other words just over half an hour to equal the entire claimed German production. The other point was to design a shell to take the fuse, the allies started with the USN 5 inch gun. It should be noted the claimed major shoot down was the USN ships reporting what they thought they had shot down. In the fights with Kamikazes the USN ships reported they needed to fire 100% VT (proximity) fuses, since there was normally no time to set and use time fuses. It was first supplied to Britain to help overcome the V1 cruise missile fired at London where it in combination with radar and computer directed guns reduced the mean number of rounds expended to destroy a V1 from 4000 to 180. The note being it was a combination of better fire control and fuses. It would appear that the 20:1 reduction came 3:1 from VT fuses and 7:1 from servo driven and computer aimed radar slaved guns. Or perhaps the other way around. I suspect optically directed servo driven computer aimed guns could have been as effective on a clear day. This ignores radar's great advantage over optics, much more accurate range information. Where optics works better is bearings, the smaller wavelengths give greater accuracy. Finally there are records of it used against German troops during the Ardennes Offensive (Battle of Bulge). It was reasoned that the Germans would not be able to reconstruct the fuses in time to make use of them. In fact the 'folklore' on the Internet is that they captured some 20,000 but did not recognize them and also that they recovered duds and reasoned that they were triggered by the Earth's magnetic Field. (Note the magnet field theory probably came from the troops themselves before being analysed by more technical branches of the German forces) Ah so the folk lore is they captured a US ammunition dump with the fused shells and then inventoried the catch, as opposed to destroying it? I don't know what the custom would have been. It is said they didn't recongise the nature of the shells. However they did recover dud shells (they must have known there was something unique about them) and surmised that they had a electronic fuse. Recovering dud shells is not something the infantry usually has time to do, it usually requires some specialists. The recovery of some shells is possible, but it would be alongside other dud shells. Given the known number of dud bombs in WWII there would be plenty of dud shells to look for. By the way the troops would not be checking the fusing of any dud rounds, but removing the shells to a safer place. The experts would be looking at things like fuses. The allied fuse workings. Technically the Allied fuse was not radar: it did not send out a pulse and listen for an echo. It had 4 tubes. One tube was part of the oscillator. When a 'target' that was about a ½ wavelength in size came within a few wavelengths it would load the amplifier and the anode current would increase. Two additional amplifiers would detect this change and then triggered the 4th valve (a gas filled thyraton) to set of the detonator. Contrary to other reports it apparently did not trigger on Doppler shift either or on frequency change. There were many shock hardening techniques including planar electrodes and packing the components in wax and oil to equalize the stresses. Given we are talking about wavelengths in the order of centimetres the axis mist have been flying very small aircraft if they were around a half wavelength in size. VT fuse opperated at about 220-280Mhz or so. A wavelenght would have been about 1.5 meters. Targets would need to be 1/4 to 1/2 a wavelenght to produce a stronger return. So the aircraft would have to be 0.75 to 0.4 metres in size? The system used compared the phase of the reflected wave, which is where wavelengths come into things, it does not apply to the size of the target. Try this for an explanation, "One method that was experimented with used radio waves transmitted from the ground. These radio waves would be reflected by the targetand received by the fuze. Once the radio waves were at a sufficient level, the fuze would activate causing the shell to explode. Another method that was more logical and became the accepted means, was to develop a fuze which was capable of obtaining its own intelligence and of using it to ignite the shell. When assembled this fuze consisted of four major parts: A miniature radio transceiver, complete with amplifier and capacitor; a battery; an explosive train; and the necessary safety devices. The theory was that the fuze transmitter, alone, would not produce sufficient signal intensity, to trigger a thyratron tube switch. However, as the projectile approached a target the radio waves reflected by the target would gradually increase and come more and more into phase with the fuze-generated signal. Once the signal level was high enough, the fuze would know that the shell could do a maximum amount of damage, and the thyratron tube switch would be triggered releasing the energy in a charged capacitor and thus igniting the shell." The German fuse workings. The fuse was based on electrostatic principles. At least this hopefully stops the previous claims the Germans handed the design to the British who then used it. I never suggested that the Allies or British coppied the German fuse,I suggested that it accelerated the allied work. Early German investigations seem to go back to 1935. There is British work going to 1937 and I suspect 1934 for optical fuses. The claimed German system used an entirely different idea to find proximity but somehow this is supposed to accelerate the project initiated in the US that used another method? Simply it is clear, like radar, people were thinking about how they could have the shell explode near a target. This is not the same thing as the Germans, yet again, being claimed to help allied technology. The circuitry of the German fuse is not precisely known to me as Ido not have the schematics however the details are in allied files refred to I do not have a circuit layout drawing. It is known that the nose of the shell was electrically insulated and isolated from the rest of the shell. It was built by the company Rheinmetall. The program was halted in 1940 then restarted in early 1944 and then terminated again due to being over run by the allies at the point that it was ready for production. The above assumes the program was producing fused shells in 1940 as opposed to heading towards the idea. After all if the restart was in early 1944 and the production facilities were over run something like 15 months later just as production was about to start it shows how long things actually took. How long the Germans really were from production. In actualy fact the 1000 test firings were conducted in 1944. There may have been firings in 1940 before cancellation but they were almost certainly not succesfull. So the Germans had a design in 1940 that did not work but this is supposed to have been of help to the allies? The US started work on the fuse in July 1940 and later developed optical and magnetic proximity fuses for mines and 4.5 inch rockets. Initial fuse testing demonstrated a sensitivity of 1-2 meters and a reliability of 80% when fired against a metal cable target. A circuit adjustment yielded an increase to 3-4 meters and a reliability of close to 95%. Further work showed a 10-15 meter sensitivity. This was with 88mm canon shells. The shell to all intents and purposes ready for production. Again no dates are given, presumably we are to believe it was ready for production in 1940, but then shut down because it was not ready for production within 6 months, see below, and the time it actually took in 1944/45 above. No, I believe there were NO test firings in 1940 that were succesfull. Well that is cleared up at least. There were considerable strides made during the war when it came to reliability and miniaturisation of radio parts, the later war experiments would have benefited from this. There are some notes kicking around somewhere on german techniques for valve seals in ceramic amplifier tubes. I believe they produced quite small ceramic valves, So, like radar, the proximity fuse were bleeding edge and were not something you could do off the shelf, additional technologies had to be developed. Note the lethal burst radius for a standard 88mm shell was around 30 feet, or 9 metres. Given the standard fire control radar some 59,000 88 mm shells were needed to cover the volume the aircraft could be in when flying at 24,000 feet. References are "Truth About the Wunderwaffen" by Igor Witowski who cites "Proximity Fuse Development - Rheinmettal Borsig A.G. Mullhausen. CIOS report ITEM nos 3 file nos XXVI -1 (1945) Capacitance based fuses became highly developed after the second world war due to their high resistance against jamming techniques. Ah, so the plan is to stop claiming the Germans gave the fuse to the allies but to claim they thought of it first and did it better. Electrostatic fuses are apparently intrinisically hightly resistent to jamming. Anything passive is harder to jam, but the fuse had to measure something to explode and jamming could provide the something. The allies looked at using electrostatic principles but preceded with radio methods instead. I belive the Germans struggled to get the range up from 3-4 meters to 10-14 meters. It looks like they had to add a small antenna cable or tailing wire to achieve this. So the allies came to the conclusion an active fuse was possible with early 1940's technology and this avoided things like having to make special shells with trailing antennas, attached to the fuse. The Germans went down the route of requiring special shells, as opposed to the allies having the ability to use the same shell with different fuses. A range of 3 to 4 metres is around 1/3 to 1/2 the lethal range of the 88mm shell. It is unlikely that the shell could have been easily degraded by jamming or chaff. (unlike the Allied shell). Yes, claim it does things better. Just ignore the idea the whole idea of window was to mimic a bomber, and all that has to be done now is to explain how the shell would discriminate against aluminium in falling foils and in aircraft flying along. Window and Chaff could be used to form a layer below the bomber to predetonate some of the fuses. So why the assertion above? (snip) Should be fun to create the mechanism to allow a high speed vibrating contact, have it survive the acceleration of the firing and then spin up to arm the shell The contact could be aligned along the axis to avoid centrifugal forces or a rotating button could be used. Try surviving the initial acceleration first given the parts have to then be able to move, after presumably bleeding some of the speed to start any vibrations. (snip) It was at this time that the Germans also abandoned their magnetron and microwave development teams and programs. Many programs suffered severely due to this; something that was to have far reaching consequences for the German war effort. It would be better to say scaled back as opposed to abandoned. Abandoned is accurate. They had to get the personel back out of the Army. They didn't even recognise the value of the magnetron since the microwave experts werent there to look at it. It was taken by some initally as proof that microwaves are not good for detecting aircraft. Like so many of Germany's experimental aircraft trials that were officially shut down but continued the same applied to the electronics sector. What would have happened if the proximity fuse was not abandoned in 1940 but development continued such that it entered service in 1943? The USAAF would have flown more night missions and deployed B-29s to Europe. The B29 wasn't reliable till late 44. The engines overheated, caught fire (they were magnesium) and then burned through the spar. Nasty. One of the main problems causing engine fires were the high ambient air temperatures at the bases used in 1944 and the heavy loads being carried given the range to target. England is cooler and closer to the targets, plus having more engineering personnel available if needed. The B-29 was really a 1945 bomber. The allies would have devoted more to flak suppression. The allies would have flown more missions on cloudy days using the better navigation aids in 1944. Note the half way point for Bomber Command for bombs on Germany was in late September 1944, the 8th was mid November 1944. It was a very end loaded campaign. The number of flak batteries out ran the German ability to provide them with proper fire control systems. Hence there were still sound locators in use in 1944 to use an extreme example. The idea of massed batteries was also driven by the amount of fire control systems needed. All guns fired at once apparently. Which shows the problems with fire controls. The massed firings did up the hit rate. Before the RAF introduced window Bomber Command was recording that around 6 to 9% of returning aircraft on night missions had flak damage, March to July 1943. This dropped to 2.85% in August and averaged 2.3% for all of 1944 and 1.4% for 1945. Window remained effective against the fire control radars for the remainder of the war. An moving target indicator called k-laus that used a 2 microsecond delay line to detect moving targets was expected to resolve window and chaff much better than wurzlaus and nurenberg. It didn't quite enter service. Yet again the Germans were going to have it but never did. The average for aircraft returning damaged by flak on night raids February to December 1942 was 6.5%, for all of 1943 5.8%. In effect a proximity fuse at around 3 to 7 times the lethality would restore to exceed the pre window hit rates. The USAAF carried window and active jammers but, of course, by day the gunners could correct their aim by eye. Some batteries even had the ability to track the H2X radars of USAAF pathfinders and use this for ranging, electronic warfare was a 2 way street. Geoffrey Sinclair Remove the nb for email. |
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