World War II Japanese radar

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RF
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World War II Japanese radar

Post by RF » Tue Oct 09, 2007 12:39 pm

Are there any published accounts on this subject, as I gather that the Japanese did not develop radar until late in the war?
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Post by lwd » Tue Oct 09, 2007 1:31 pm

I think there is some info in the strategic bombin survey and in the naval technical mission. There's also some stuff on the web but not a great deal. The Japanese had radar by mid war (depending on what you mean by had) but tended not to use it. Both they and the Germans were, legitamatly, afraid of giving away their locations if they made extensive use of radar. The allies by mid war had so many that it giving away the location of a radar equiped unit was hardly significant (by late war it was even on PT boats).

The IJN forum is a pretty good place to ask for this sort of thing for naval radar anyway. I think I've seen something about air defence radars in Japan itself but I don't remember what or where.

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Re: WW2 Japanese radar

Post by Tiornu » Tue Oct 09, 2007 8:45 pm

Nakagawa, Yasuzo. Japanese Radar and Related Weapons of World War II. Aegean Park Press, 1997.
A very good overview.

Brown, Louis. A Radar History of World War II. Institute of Physics Publishing, 1999.
This is a great book, obviously with a larger scope.

Burns, Russell (ed.) Radar Development to 1945. Peter Peregrinus Ltd., 1988.
A series of articles covering each major combatant.

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Post by RF » Wed Oct 10, 2007 12:19 pm

Tiornu,

Thanks for the above references.
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Post by Lutscha » Wed Oct 10, 2007 1:40 pm

Despite the name of the link a quite good overview:

http://www.star-games.com/exhibits/japa ... radar.html

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Post by Dave Saxton » Sun Oct 14, 2007 7:59 pm

Japanese scientists were steeped in the world wide interest and early research in the radar concept, that existed among academics during the 1930's. Indeed the Japanese research community had been working with magnetrons, even cavity magntrons, for many years. Where the Japanese dropped the ball; was that much of what they developed remained at an experimental status in the labratories, and didn't make it to a practical application.

Another factor was the intense and rediculous inter -service rivalry that existed between the IJN and the IJA, diluting the efforts. This undoubtly retarded development of practical military applications.

One Japanese scientist was informed by the German profesor Barkhausen that the German Navy already had an operational radar in 1937, and that they better get in gear. It appears that the Japanese worked hard to catch up and that they attempted to develop radars of centimetric wave length from the out set, although they had no knowlege of the 1940 British breakthroughs in that regard. They appear to have developed centimetric radars independantly.

The IJN equiped, IIRC, Hyuga with a 10cm radar in May 1942. This means that the IJN had a centimetric radar deployed within 6 months of the British deployment of Type 271, and within months of the first combat use of SG by the USN.

When the Marines captured the airfield on Guadalcanal, they also captured an intact air warning radar. The Naval Research Lab found this set to be rather crude, but this was just a simple air warning set for out laying outposts. This may have or may not have been representive of the general technical advancement of Japanese radar technology.

The Japanese dove on the wrecks of Prince of Wales and Repulse to recover the radar equipment. I don't know the results of this adventure, but it may have given them some ideas for the development of firecontrol radar concepts? They also captured some British Army gunlaying radars in Malaya.

The Japanese were very interested in the Telefunken Wurzburg flak direction radars. It took several attempts to transfer an example and the technical plans intact to Japan by submarine. Very late in the war they had at least one example of a Wurzburg copy up and working.

A GEMA engineer was also sent to Japan by submarine. However, he was not given the required security clearances by the IJN to be involved with their research teams. Instead he spent his time designing and building test and calibration equipment.

It's very difficult to find reliable data on wartime Japanese radar technology as most of the equipment and the documentation was destroyed by the Japanese themselves.

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Post by lwd » Mon Oct 15, 2007 1:25 pm

Part of their problem with radar may well have stemmed from their view of how the war wold go. They knew that in order to win they had to win quickly. The hope was that PH would convince the US to seek a treaty in the first 6 months to 1 year. They really weren't going to get much out of radar by the end of 42 so why spend a great deal of time on it.

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Post by Tiornu » Mon Oct 15, 2007 9:54 pm

It wasn't a strategic decision but a lack of patronage by anyone with the authority to make it happen.

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Post by RF » Wed Oct 17, 2007 12:48 pm

lwd wrote:Part of their problem with radar may well have stemmed from their view of how the war wold go. They knew that in order to win they had to win quickly. The hope was that PH would convince the US to seek a treaty in the first 6 months to 1 year. They really weren't going to get much out of radar by the end of 42 so why spend a great deal of time on it.
This I think reflects on the failure of the Axis to have any concept of Grand Strategy. The full US reaction to PH was evident within days, yet the Japanese still failed to develop any fall back strategy to deal with a long war, in particular to develop new weapons to update what they already had, while they still had time to do it.
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Re: WW2 Japanese radar

Post by USS ALASKA » Tue Sep 22, 2009 8:48 pm

RF wrote:Are there any published accounts on this subject, as I gather that the Japanese did not develop radar until late in the war?
Sorry to drag up an old thread - another book that has info on Japanese Radars is "The History of US Electronic Warfare, Volume 1" by Alfred Price. http://www.amazon.com/History-US-Electr ... 630&sr=1-6 Don't be fooled by the title.

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Re: World War II Japanese radar

Post by RF » Mon Sep 28, 2009 1:43 pm

Thanks for the post USS ALASKA, I'll look into this.
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Re: World War II Japanese radar

Post by USS ALASKA » Tue Sep 29, 2009 1:52 pm

RF wrote:Thanks for the post USS ALASKA, I'll look into this.
Is there any info you are looking for in particular or just a general history?

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Re: World War II Japanese radar

Post by RF » Fri Oct 02, 2009 7:57 am

Basically general history and actually curiosity, because I had believed that the Japanese never had any radar in WW2 apart from that supplied to them by the Germans.
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Re: World War II Japanese radar

Post by USS ALASKA » Fri Oct 02, 2009 4:11 pm

Sir, http://www.ibiblio.org/hyperwar/USN/rep/NTM/NTM.html lists these reports written by the US Naval Technical Mission to Japan;

Electronic Reports:
E-01 Japanese Submarine and Shipborne Radar.
E-02 Japanese Airborne Radar.
E-03 Japanese Land-Based Radar.
E-04 Japanese Centimeter Wave Technique.
E-05 Japanese Radio and Radar Direction Finders.
E-06 Japanese Anti-Radar Coverings.
E-07 Japanese Radar Countermeasures and Visual Signal Display Equipment.
E-08 Japanese Radio Equipment.
E-09 Japanese Navigational Aids.
E-10 Japanese Sonar and ASDIC.
E-11 Japanese Communication Systems.
E-12 Japanese Experimental Radar.
E-13 Japanese Electronic Tubes.
E-14 Japanese Magnetic Airborne Detector.
E-15 Power Supplies for Japanese Electronics.
E-16 Japanese Antennae.
E-17 Japanese Radio, Radar, and Sonar Equipment.
E-18 Japanese Radio Apparatus Construction Methods.
E-19 Japanese Electronic Equipment Construction Materials.
E-20 Japanese R.F. Transmission Lines, Wave Guides, Wave Guide Fittings, and Dielectric Materials.
E-22 Japanese Radio Frequency Measuring Technique.
E-23 Japanese Insulation Materials.
E-26 Japanese Electronic Harbor Protection Equipment.
E-28 Japanese Electronics -- General.
E-29 Japanese Electronics Training and Operating Techniques.
E-30(N) Japanese Electronics -- Miscellaneous.

Other reports listed on that page have bearing on this topic also.

Then to get loads of free info, go to http://www.fischer-tropsch.org/ , use the search function and type in ‘Japanese Radar’ or the name of any of the above reports. Should get you a pdf file to download.

HTH.

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Re: World War II Japanese radar

Post by USS ALASKA » Fri Oct 02, 2009 4:46 pm

Also,
http://www.vectorsite.net/ttwiz_07.html#m7

[7.7] ORIGINS OF JAPANESE RADAR TECHNOLOGY

* While the British were coming to grips with German radar, the Japanese were developing their own radar systems completely out of sight of Allied intelligence.

The main reason the Japanese effort remained unknown was because it lagged so far behind Allied and German efforts. Ironically, the Japanese had good technical minds, and had even developed an effective cavity magnetron in 1939, well before the British. However, the country's militaristic leadership was focused on "bushido", the "warrior ethic", and did not give technical development high priority, tending to think that discipline, aggressiveness, and suicidal courage would always carry the day, with the end result that sometimes the role of sensibility and cleverness in the mix was not appreciated by all. Limited resources also played a role.

Substantially compounding such problems was the interservice rivalry between the Imperial Japanese Army (IJA) and Imperial Japanese Navy (IJN), which was even worse than German interservice rivalries, approaching a lunatic comedy at times, squabbling like "dogs and monkeys" as the Japanese saying has it. The IJA was modeled on the Kaiser's army, while the IJN was modeled on the British Royal Navy, and to an extent both organizations retained the mindsets of their "parents". The fact that the military dominated the civilian government, instead of the other way around, left no higher power to straighten out the feud, or to create any higher-level research organization like the US OSRD.

The Japanese had tinkered with aircraft interference detection schemes in the late 1930s, developing a system that detected aircraft flying through a beam sent from a transmitter and receiver separated by up to hundreds of kilometers, operating at 7.5 to 3.75 meters (40 to 80 MHz). This system could only detect that an aircraft was flying through the beam somewhere, providing little or no other information, but was actually deployed beginning in the 1940:1941 timeframe as the "IJA Type A". About a hundred stations were set up, apparently mostly in China.

The Japanese were slow to get started on pulsed radar. In early 1941, Japanese technical experts paid a visit to Germany to trade information with their Axis ally. Characteristically, the IJA and IJN each sent their own team, with no real coordination of their travel plans or their meetings with their hosts.

When they got to Germany, it didn't turn out to be another Tizard mission. The Germans and Japanese were careful about what they told each other. The Japanese were allowed to inspect a Wuerzburg for a short time, but although they saw a Freya, the Germans wouldn't talk to them about it. On their own part, the Japanese didn't mention their cavity magnetron. It appears the Germans thought the Japanese had little to teach them, and the Japanese might have believed the same thing themselves, since the Germans seemed so obviously far ahead of them. There was no point in bargaining over the cavity magnetron if it was almost certainly nothing new to the Germans. Whatever the case, the failure to communicate was a benefit to the Allied cause.

* The Japanese returned home that summer. In the meantime, the IJN had become alarmed over evidence of Allied naval radars, and when the experts returned the Navy began an effort to develop radars of their own. The experts quickly threw together a pulse-radar prototype, operating at 4.2 meters (71.4 MHz), and had a 3 meter (100 MHz) fixed-site warning radar set designated "IJN Mark I Model 1" in production in the fall of 1941. Pulse width was long, from 10 to 30 microseconds, peak power was 5 kW, and maximum range was about 145 kilometers (90 miles). PRF was apparently variable, in the range of 530 to 1,250 Hz. About 80 were built.

Incidentally, the designation scheme is a bit confusing, and an interesting minor example of the way that Easterners and Westerners tend to think sideways relative to each other. The mark number actually specified the class of radar, with a "Mark I" being a land-based set, "Mark II" a shipboard set, "Mark IV" being a fire-control radar, and "Mark VI" being an airborne radar. The model number actually specified the type sequence of a radar within its class.
The IJN Mark I Model 1 was a crude set, but the speed with which it was developed was impressive, another demonstration that if the Japanese were slow in radars it wasn't for lack of talent. They went from this set to a shipboard air and surface search set, the "IJN Mark II Model 1". Like the IJN Mark I Model 1, the pulse width was from 10 to 30 microseconds, peak power was 5 kW, and the PRF was similar, 500 to 1,100 Hz. The major difference was that the Mark II Model 1 operated around 1.5 meters (200 MHz). Maximum range for an aerial target was about 145 kilometers (90 miles), and roughly a fifth of that for a large naval target.

About 80 IJN Mark II Model 1s were built. Unfortunately, as was often the case with early shipboard sets built by other combatants, the Mark II Model 1 wasn't reliable enough to put up with harsh sea conditions, and feedback from Imperial Navy crews was very negative.

* The IJA was pursuing its own, of course almost completely independent, radar development effort in parallel. They had limited success, building a few preliminary types that proved totally unsuitable for field use, but then coming up with a 4 meter (71.4 MHz) warning-radar set designated the "IJA Tachi 6". It was a floodlight system, comparable to Chain Home in many ways, featuring an omnidirectional or wide angle transmitter with three or four moveable, steerable receiver antennas. The Tachi 6 had a pulse width of 25 to 35 microseconds, a peak power of 10 to 50 kW, a PRF that could be switched from 500 to 1,000 Hz, and a maximum range of 300 kilometers (185 miles). About 350 were built, first going into operational service in 1942.

The IJA radar designation scheme is also a bit confusing. "Tachi" is a hybrid word, with the "Ta" standing for the "Tama Institute", the IJA organization that did the technical work, and "chi" derived from the Japanese word for "Earth", and so the word means "Tama Institute ground-based radar".

Similarly, "Tase" meant a shipboard radar and "Taki" meant an aircraft-based radar, though the IJA would never actually field a Tase radar. This might seem logical, since a shipboard radar was clearly the province of the IJN, but it is interesting to note that the IJA actually built their own submarines during the war as supply vessels for isolated island outposts, a particularly vivid example of the way the two services worked at cross purposes.

http://www.vectorsite.net/ttwiz_08.html

[8.5] JAPANESE RADAR TECHNOLOGY AT WAR

* At the end of 1941, the Japanese began a wide-ranging offensive that swept through the colonial possessions of the British, Americans, and Dutch in the western Pacific, reaching as far southeast as the north coast of New Guinea to threaten Australia. Among the benefits of this spectacular wave of conquest was the fact that the Japanese obtained a number of British GL-type sets in Singapore, as well as a US SCR-268 set and a damaged US SCR-270 set on Corregidor.

The IJA put a modified version of the GL into production as the "IJA Tachi 3". It operated on a band around 3.75 meters (80 MHz), had a pulse width of one to two microseconds, a peak power of 50 kW, a PRF of 1,000 or 2,000 Hz, and a maximum range of about 40 kilometers (25 miles). About 150 were built by Sumitomo, with the type going into service in early 1944. The Tachi 3 set was the first Japanese set to incorporate Yagi antennas, which was a great irony, since such antennas were the invention of Hidetsugu Yagi, a Japanese electronics researcher of global stature. To add to the irony, Dr. Yagi had been involved in the development of the IJA Type A interference detector.

On their part, the IJN recognized the SCR-268 as a good piece of gear and put a derivative of it into production as the "IJN Mark IV Model 1". It operated in a band around 1.5 meters (200 MHz), had a pulse width of 3 microseconds, a peak power of 30 kW, a PRF of 2,000 Hz. and a maximum range of about 48 kilometers (30 miles). It was followed by the improved "IJN Mark IV Model 2", which had basically the same general specifications except that the PRF was reduced to 1,000 Hz. The Japanese built a few hundred of these radars in all.

The IJA also tried to build derivatives of the SCR-268 in the form of the "IJA Tachi 1", "IJA Tachi 2", and "IJA Tachi 4", all operating on the 1.5 meter (200 MHz) band used by the SCR-268, but these radars did not prove satisfactory and were only built in small numbers. Late in the war, the IJA did introduce a much more workable derivative of the Tachi 4, the "IJA Tachi 31", also operating at 1.5 meters (200 MHz), with 70 built.

* In the meantime, both the IJN and IJA fielded derivatives of their earlier fixed-site radars. The IJN Mark I Model 1 was followed in 1942 by about 300 of a lighter transportable 1.5 meter (200 MHz) version, the "IJN Mark I Model 2", and then in 1943 about 1,500 of an even lighter portable version, the 2 meter (150 MHz) "IJN Mark I Model 3".

As if in parallel lockstep, the IJA followed their Tachi 6 in 1943 with about 60 transportable 3 meter (100 MHz) "IJA Tachi 7" sets, and in 1944 followed that with about 400 portable "IJA Tachi 18" sets, operating in the same band.

Other than being lighter, these radars were no great advance over their predecessors, being roughly comparable to the British MRU. However, since the Japanese had developed their own magnetron, in fact well ahead of the Allies, they also developed their own 10 cm (3 GHz) microwave set for naval warfare. The "IJN Mark II Model 2" radar was introduced in 1942, and was well-received by naval crews as a great step ahead of the unsatisfactory longwave Mark II Model 1. About 400 were built and deployed on a range of vessels.

The Mark II Model 2 had a peak power of 2 kW, a pulse width of 2 to 10 microseconds, a PRF of 2,500 Hz, and a range of about 35 kilometers (22 miles) against a large naval surface target. It had separate cone-shaped transmit and receive antennas, giving it the odd appearance of giant toy binoculars. It did not have a PPI, no operational Japanese set ever did, which greatly limited its usefulness for naval operations.

The Japanese also developed a lightweight longwave set, the "IJN Mark II Model 4", operating at 1.5 meters (200 MHz), for use on small vessels and submarines. It is unclear if it saw much service.

* During the first months of the US war against Japan, the Americans were so overwhelmed that worrying about Japanese radar capabilities didn't even make the list. The issue didn't bob to the surface until the US Marines landed on Guadalcanal in the Solomon Islands on 7 August 1942. The landings were not heavily opposed -- a situation that gave a completely misleading impression of what to expect in the future -- and the Marines quickly captured an IJN Type I Model 1 radar. The catch came as a surprise, apparently less because anyone thought the Japanese didn't have radar than because few had given the matter much thought. The Japanese radar was dismantled and shipped stateside. NRL researchers found it crude, even in comparison with early American radars such as the SCR-270 and CXAM.

SIGINT receivers were quickly installed on submarines and aircraft to hunt for more Japanese radars. A Consolidated B-24 Liberator ferret that had been fitted with various SIGINT gear, including some lab breadboards, performed probes of the Japanese-held island of the Kiska in the Aleutians in March 1942, and discovered the signatures of two more IJN Type 1 Model 1 radars, which the SIGINT operator reported sounded exactly like the signature of the US SCR-270 longwave radar. Consolidated PBY Catalina flying boats were also configured as ferrets, and more Japanese radars were soon identified.
Submarine ferrets would prove as effective as their flying brethren, possibly more so because the enemy generally didn't know submarines were around and didn't turn off their emitters. However, no other types of Japanese radars were detected through most of 1943, though there were rumors and bogus "sightings" of other types, such as airborne radars that the Japanese simply didn't have at the time.

Better information began to trickle in towards the end of the year, and in February 1944, following the capture of Kwajalein island, the Americans found documents describing a number of Japanese radars, most interestingly the centimetric Mark II Model 2 shipboard radar. Further landings during the spring and summer revealed more data about Japanese radars, including some sets captured intact.

http://www.vectorsite.net/ttwiz_09.html

[9.4] ALLIED COUNTERMEASURES AGAINST JAPAN

* While the Americans closed in on Japan, the Japanese tried to catch up with radar technology, but it was even more of a case of too little, too late.

The IJN did develop a longwave airborne search radar, the 2 meter (150 MHz) "IJN Mark VI Model 2", with some similarities to the British ASV.II. It appeared in service in early 1944 and was mounted on Mitsubishi G4M "Betty" twin-engine bombers, with a large Yagi antenna in the nose and horizontal dipoles on the fuselage. About 2,000 sets were built. Of course, the IJA had to develop a comparable set in parallel, designated the "Taki 1", that operated on the same band. About a thousand of them were built. These sets did prove useful in action, but the Allies were striding far ahead in radar technology.
In the spring of 1944, Boeing B-29 Superfortress heavy bombers were beginning raids on the Japanese home islands from bases in China. Instead of using dedicated ferret machines, some of the B-29s were fitted with SIGINT gear and jammers to perform countermeasures tasks as part of their normal bombing mission.

The Ravens on board the B-29s picked up Japanese surface radars. While there was no evidence that Japanese night fighters were carrying AI radars, there were some cases where they seemed to lose the scent on a B-29 when the bomber turned off its IFF. This hinted strongly that the Japanese had a device that could activate Mark III IFF, possibly something they had obtained from the Germans, but in the end the incidents turned out to be coincidences. They had no such capability.

The China raids were given up in early 1945. They were logistically difficult, since all the supplies, fuel, bombs, and so on for the operations had to be airlifted over the Himalayas, and more embarrassingly the Japanese got tired of the raiders and simply overran the airbases. All the supplies flown at such effort to the bases were blown up or burned to keep them from falling into Japanese hands.

The capture of the Marianas that spring provided a much more convenient and secure base for Superfortress attacks on Japan. Superfortresses pounding the Japanese home islands all carried their own jammers. For additional protection, Superfortresses dedicated to the jamming mission, known as "Porcupines" for their collection of antennas, or "Guardian Angels" for obvious reasons, accompanied the formations. Window and Rope were also used intensively.

Interrogation of Japanese radar operators after the war showed that the effects of Window and Rope were mixed, but the active jamming systems were brutally effective, completely blinding Japanese radars. Ironically, since the Allies knew the IJA Tachi 3 radar was a variant of the British GL Mark II, the Americans tried to refine their jamming techniques by using GL.IIs obtained from the British as test systems. However, the information provided from this exercise wasn't available until the war was all but over.

* The thorough defeat of Japanese electronics technology was an embarrassment for the Japanese, who had shown flashes of brilliance that had been squandered.

Although the Japanese did eventually develop IFF, they never got it into mass production, and the IJN and the IJA naturally didn't cooperate on the matter, with both services pursuing separate IFF schemes. As their development of the cavity magnetron and early use of chaff showed, the Japanese had people with good ideas, but radar work remained organizationally muddled and crippled by inadequate resources. The shortage of good-quality electronic components was so severe that the IJA and IJN, despite all their antagonisms, managed to form a joint committee to try to work out their supply problems. Many radar engineers were drafted into the military to fight in combat, throwing valuable technical talent into the meat grinder.

Such improved technologies as were built amounted to nothing. For a striking example, with Germany and Japan and both at war with the US and Britain, the Germans sent a submarine to Japan with the design of the Metox longwave radar warning receiver, almost precisely at the time the Allies were moving up to centimetric sets. The Japanese built about 2,000 copies and found them more or less useless.

The IJN was working on AI radars for night fighters, but never got them into service, and attempts by the IJN to adapt the centimetric 10 cm / 3 GHz Mark 2 Model 2 as an air-defense radar met the same fate. Since the IJA Tachi 6 series warning radars had little height-finding capability, the IJA did try to develop height-finding radars, including the "IJA Tachi 20" and "IJA Tachi 35", but only a few ever saw action.

The Japanese developed jammer systems that never got into combat, and work was squandered on a futile attempt to build a radio-energy death ray. The Germans provided the Japanese with Wuerzburg radar technology by submarine. The Japanese were still trying to get Wuerzburg into production at the end of the war. Of course, the IJA and IJN had separate Wuerzburg development programs.

The Japanese last-stand defense was brave, determined, and doomed. In the electronic field, they were so far behind that even if they had managed to field their improved systems, the Americans would have quickly neutralized them.

American radar helped deal out the final blows. Both atomic bombs dropped on Japan at the end of the war were triggered to airburst at 580 meters (1,900 feet) by a proximity fuze system, though it was derived from the AN/APS-13 tail-warning radar. The fuze system included four redundant units, known as "Archies", to reduce the possibility of a premature detonation, with the bomb detonating only when two of the Archies agreed that they had dropped through the critical altitude. There was a backup mechanical fuze system in case the electronic system failed, but the Archies worked as advertised.

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