Ju-88 nightfighter with FuG-202 Lichtenstein radar.
Big Ego versus Dowding; nightfighters > .
https://en.wikipedia.org/wiki/Junkers_Ju_88 .
https://en.wikipedia.org/wiki/Lichtenstein_radar .
https://en.wikipedia.org/wiki/Night_fighter .
Thursday, September 19, 2019
Ju-88s + radar captured
Ju-88 nightfighter with FuG-202 Lichtenstein radar.
Big Ego versus Dowding; nightfighters > .
https://en.wikipedia.org/wiki/Junkers_Ju_88 .
https://en.wikipedia.org/wiki/Lichtenstein_radar .
https://en.wikipedia.org/wiki/Night_fighter .
Wednesday, September 18, 2019
Kammhuber Line
Operation Biting - Raid on Bruneval - tnh > .
The Kammhuber Line was the Allied name given to the German night air defense system established in July 1940 by Colonel Josef Kammhuber. It consisted of a series of control sectors equipped with radars and searchlights and an associated night fighter. Each sector would direct the night fighter into visual range with target bombers.
The Line was very effective against early Bomber Command tactics. However, the German method was analyzed by the RAF and a counter measure developed. On the night of 30/31 May 1942 in its 1,000 plane raid against Cologne Bomber Command introduced the use of the bomber stream. The concentration of bombers through a few of the boxes resulted in the defenses being overwhelmed. In response, the Germans converted their ground radar into a radar network, which would follow the path of the British bombers, while a controller directed the night fighters into the stream. Measure and counter measure continued until October 1944, when German defenses were no longer able to respond..........
The Line was very effective against early Bomber Command tactics. However, the German method was analyzed by the RAF and a counter measure developed. On the night of 30/31 May 1942 in its 1,000 plane raid against Cologne Bomber Command introduced the use of the bomber stream. The concentration of bombers through a few of the boxes resulted in the defenses being overwhelmed. In response, the Germans converted their ground radar into a radar network, which would follow the path of the British bombers, while a controller directed the night fighters into the stream. Measure and counter measure continued until October 1944, when German defenses were no longer able to respond..........
When Germany organised its air defences into the Kammhuber Line, it was realised by the British (Bomber Command's Operational Research Section (BC-ORS)) that if the RAF bombers were to fly in a bomber stream they could overwhelm the night fighters who flew in individual cells directed to their targets by ground controllers. It was then a matter of calculating the statistical loss from collisions against the statistical loss from night fighters to calculate how close the bombers should fly to minimise RAF losses.
British intelligence soon discovered the nature of the Kammhuber Line and started studying ways to defeat it. At the time RAF Bomber Command sent in their planes one at a time to force the defenses to be spread as far apart as possible, meaning that any one aircraft had to deal with little concentrated flak. This also meant the Himmelbett centres were only dealing with perhaps one or two planes at a time, making their job much easier.
At the urging of R.V. Jones, Bomber Command reorganized their attacks into streams of bombers – the so-called Bomber stream, carefully positioned so the stream flew down the middle of a single cell. Data provided to the British scientists allowed them to calculate that the bomber stream would overwhelm the six potential interceptions per hour that the German "Tame Boar" (Zahme Sau) night fighters could manage in a Himmelbett zone. It was then a matter of calculating the statistical loss from collisions against the statistical loss from night fighters to calculate how close the bombers should fly to minimise RAF losses. The introduction of Gee radio navigation in 1942 allowed the RAF bombers to fly by a common route and at the same speed to and from the target, each aircraft being allotted a height band and a time slot in a bomber stream to minimize the risk of collision. The first use of the bomber stream was the first 1,000 bomber raid against Cologne on the night of 30/31 May 1942. This tactic was extremely effective, leading to fighting between Kammhuber and Erhard Milch, his boss.
Although the success rate of the Line dropped, the network of radars and plotting stations continued to prove their worth. Now when a raid started, night fighters from any base within range were directed into the stream, where it was hoped they would be able to find aircraft with their radar. At the same time a massive building program started to add hundreds of Würzburgs to the system, although the infrastructure needed was extensive. The boxes were initially the radius of the Würzburg radars, about 22 miles, but more powerful radar later on made the boxes up to 100 miles across. Eventually, the line of boxes was several deep, especially around larger towns and the Ruhr valley. Once again the system started to score increasing successes against the British raids.
The British were ready for this development, and as soon as the rates started to improve – for the Germans – they introduced "Window". Dropping strips of foil from a number of "lead" bombers, the German radar operators saw what appeared to be a stream entering their box, each packet of chaff appearing to be a bomber on their displays. Night fighters were then sent to attack this stream, only to find empty space. Just as the fighters reached the false stream, the "real" stream appeared hundreds of miles away, too far to be attacked. The first time this was used was during Operation Gomorrah (a week-long bombing campaign against Hamburg) and proved spectacularly effective. The German radar operators eventually learned to spot the lead bombers at the edge of the windowing, making it less effective. The British had held back from introducing Window for over a year lest the technique be adopted by the Germans and used against British cities.
A more sophisticated method for blinding the German radar was "Mandrel", a jamming signal broadcast from aircraft accompanying the bomber stream or later certain bombers themselves. This progressed into jamming techniques against individual German radar types and spoofing radars to see bomber streams that weren't there. The British also attacked the communications between ground stations and fighters, with Operation Corona, broadcasting false directions in authentic accents over the radio.
One other element was long-range nightfighters operating against the German nightfighters, using a system called "Serrate" to home in on the German nightfighter radar signals. At least three squadrons equipped with Bristol Beaufighter and de Havilland Mosquito were part of No. 100 Group RAF supporting Bomber Command with electronic countermeasures.
https://en.wikipedia.org/wiki/Operations_research
.......
The Line was very effective at first, but was soon rendered useless by a simple change in tactics. The RAF directed all of its bombers to fly in a single stream, overwhelming the sectors, who could only intercept a single aircraft at a time. This led to a dramatic drop in interception rates compared to the raid size. The Line was eventually turned into a radar network, and the night fighters improved with their own radar sets to allow them to hunt on their own.
https://en.wikipedia.org/wiki/Kammhuber_Line .
Kettenkrad
The Sd.Kfz. 2 (Sonderkraftfahrzeug 2), better known as the Kleines Kettenkraftrad HK 101 or Kettenkrad for short (pl. Kettenkräder; where Ketten means "chains" or "tracks" and krad is the military abbreviation of the German word Kraftrad, the administrative German term for motorcycle), started its life as a light tractor for airborne troops. The vehicle was designed to be delivered by Junkers Ju 52 aircraft, though not by parachute. The vehicle had the advantage of being the only gun tractor small enough to fit inside the hold of the Ju 52, and was the lightest mass-produced German military vehicle to use the complex Schachtellaufwerk overlapped and interleaved road wheels used on almost all German military half-track vehicles of WW2.
Steering the Kettenkrad was accomplished by turning the handlebars: Up to a certain point, only the front wheel would steer the vehicle. A motion of the handlebars beyond that point would engage the track brakes to help make turns sharper. It was also possible to run the vehicle without the front wheel installed and this was recommended in extreme off-road conditions where speed would be kept low.
The Sd.Kfz. 2 was designed and built by the NSU Werke AG at Neckarsulm, Germany. Patented in June 1939, it was first used in the invasion of the Soviet Union in 1941. Later in the war Stoewer from Stettin also produced Kettenkrads under license, accounting for about 10% of the total production.
Most Kettenkräder saw service on the Eastern Front, where they were used to lay communication cables, pull heavy loads and carry soldiers through the deep Russian mud. Later in the war, Kettenkräder were used as runway tugs for aircraft, especially for the Messerschmitt Me 262 jet fighter, and sometimes the Arado Ar 234 jet reconnaissance-bomber. In order to save aviation fuel, a German jet aircraft would be towed to the runway, rather than taxiing under its own power.
The vehicle was also used in the North African theater and on the Western Front.
The Kettenkrad came with a special trailer (Sd.Anh.1) that could be attached to it to improve its cargo capacity.
Being a tracked vehicle, the Kettenkrad could climb up to 24° in sand and even more on hard ground.
Only two significant sub-variations of the Kettenkrad were constructed. Production of the vehicle was stopped in 1944, at which time 8,345 had been built. After the war, production resumed at NSU. Around 550 Kettenkräder were built for agricultural use, with production ending in 1948 (some sources say 1949).
Tuesday, September 17, 2019
Lorenz Beam
Prior to the start of WW2, the Germans deployed the system at many Luftwaffe airfields in and outside Germany and equipped most of their bombers with the radio equipment needed to use it. It was also adapted into versions with much narrower and longer-range beams that was used to guide the bombers on missions over Britain, under the name Knickebein and X-Gerät.
Beam navigation works for a single point in space, making it useful for landing or bombing, but not as a general purpose navigation system. This led to a rotating version of the same system for air navigation known as Elektra. Further development produced a system that worked over very long distances, hundreds or thousands of kilometres, known as Sonne (or often, Elektra-Sonnen) that allowed aircraft and U-Boats to take fixes far into the Atlantic. The British captured Sonne receivers and maps and started to use it for their own navigation under the name Consol.
...
The Lorenz system worked by feeding a special three-element antenna system with a modulated radio signal. The signal was fed to the centre dipole, which had a slightly longer reflector element on either side set slightly back. A switch rapidly alternated the opened midpoint connection of each reflector in turn, sending the beam slightly to the left and then slightly to the right of the centreline of the runway. The beams widened as they spread from the antennas, so there was an area directly off the runway approach where the two signals overlapped. The switch was timed so it spent longer on the right side of the antenna than the left.
Lorenz used a single radio transmitter at 33.33 MHz (Anflugfunkfeuer) and three antennas placed in a line parallel to the end of the runway. The center antenna was always powered, while the other two were short-circuited by a mechanical rotary switch turned by a simple motor. This resulted in a "kidney" shaped broadcast pattern centered on one of the two "side" antennas depending on which antenna had been short-circuited. The contacts on the switch were set so that one antenna was shorted for the time to be considered a "Dot" by a morse operator and the other as a "Dash". The signal could be detected for some distance off the end of the runway, as much as 30 km. The Lorenz obtained a sharper beam than could be created by an aerial array by having two lobes of signal.
An aircraft approaching the airport would tune one of their radios to the Lorenz frequency. If the crew was on the left side of the centreline, they would hear a series of short tones followed by long pauses, meaning the aircraft was on the "dot" side of the antenna. Hearing the "dots", they would know that they had to turn to the right in order to fly down the centreline. If the crew was on the right side of the centerline, they would hear a series of long tones followed by short pauses, meaning the aircraft was on the "dash" side of the antenna. Hearing the "dashes", they would know that they had to turn to the left in order to fly down the centreline. In the centre, the radio would receive both signals, where the dots filled in the gaps in the dashes and produced a continual signal, the so-called "equisignal". Flying in the known direction of the runway and keeping the equisignal on the radio, the Lorenz could guide an aircraft down a straight line with a relatively high degree of accuracy, so much so that the aircraft could then find the runway visually except in the worst conditions.
https://en.wikipedia.org/wiki/Lorenz_beam .
https://en.wikipedia.org/wiki/Battle_of_the_Beams .
Monday, September 16, 2019
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sī vīs pācem, parā bellum
igitur quī dēsīderat pācem praeparet bellum therefore, he who desires peace, let him prepare for war sī vīs pācem, parā bellum if you wan...
