Lorenz beam
Encyclopedia
The Lorenz beam blind landing system was an air radio navigation system in use from the late 1930s. The name refers to the company that produced the system; Lorenz referred to it simply as the Ultrakurzwellen-Landefunkfeuer, German
for "ultra-short-wave landing radio beacon", or LFF. Prior to the World War II
the Germans had deployed the Lorenz blind-landing
aid at many airport
s in and outside Germany, and equipped most of their bombers with the radio equipment needed to use it.
The basic idea behind the short-range LFF system was later developed into a long-range 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-Boat
s 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.
in 1934 and sold around the world. The Lorentz company was founded in 1880 by Carl Lorenz and is now part of ITT
.
Lorenz used a single radio transmitter
at 38 MHz 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 switched on and off in turn, fed from a common signal. With two of the antennas powered, the presence of the third resulted in a "kidney" shaped broadcast pattern centered on one of the two "side" antennas. The broadcast was switched so that the left antenna, as seen looking toward the runway on approach, was turned on only briefly, sending a series of "dots" 1/8 of a second long repeating once a second. When the left antenna was switched off the signal was sent to the right antenna instead, broadcasting a series of 7/8th second long "dashes". 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 runway would tune his radio to the broadcast frequency and listen for the signal. If they heard a series of dots, they knew they were off the runway centerline to the left (the dot-sector) and had to turn to the right to line up with the runway. If they were off to the right, they would hear a series of dashes instead (the dash-sector), and turned left. Key to the easy operation of the system was an area in the middle where the two signals overlapped, where the dots of the one signal "filled in" the dashes of the other, resulting in a steady tone known as the equi-signal. By adjusting their path until they heard the equi-signal, the pilot could align their aircraft with the runway for landing.
Two small radio beacons were also used with Lorenz, one 300 m off the end of runway, the HEZ, and another 3 km away, the VEZ, also broadcast on 38 MHz and modulated at 1700 and 700 Hz, respectively. These signals were broadcast directly upward, and would be heard briefly as the aircraft flew over them. To approach the runway, the aircraft would fly to a published altitude and then use the main directional signals to line up with the runway and started flying toward it. When they flew over the VEZ they would start descending on a standard glide slope, continuing to land or abort at the HEZ depending on whether or not they could see the runway.
Lorenz could fly a plane down a straight line with relatively high accuracy, enough so that the aircraft could then find the runway visually in all but the worst conditions. However it required a fairly constant monitoring of the radio by the pilot, who would often also be tasked with talking to the local control tower
. In order to ease the workload, Lorenz later introduced a cockpit indicator that could listen to the signals and display the direction to the runway centerline as an arrow telling the pilot which direction to turn. The indicator also included neon lamp
to indicate when the aircraft crossed over the marker beacons. Later derivatives of the system had signals of equal length in the pattern left-right-silence, to operate a visual indicator in the cabin.
The Lorenz system was similar to the Diamond-Dunmore equi-signal radio guidance system, developed by the US Bureau of Standards in the early 1930s.
as the basis of a number of blind bombing aids, notably Knickebein ('crooked leg') and the X-Gerät ('X-Apparatus'), in their bombing offensive against English cities during the winter of 1940/41. X-Gerät was very similar to LFF, modifying it only slightly to be more highly directional and work over much longer distance. Using the same frequencies allowed their bomber
s to use the already-installed LFF receivers, although a second receiver was needed in order to pinpoint a single location.
These systems involved cross-beams of the same characteristics but on a different frequency, which would both enable the pilot to calculate his speed (from the time between crossing the Fore Cross Signal and crossing the Main Cross Signal), and indicate when he should drop his payload. The calculation was performed by a mechanical computer. Lorenz modified this system to create the Viktoria/Hawaii lateral guidance system for the V-2 rocket.
, known as the "Baby Blitz".
A further operational drawback of the system was that bombers had to follow a fixed course between the beam transmitter station and the target; once the beam had been detected, defensive measures were made more effective by knowledge of the course.
operates, such that to attain the sharpness achieved by the Lorenz system with a single beam (approximately 1 mile wide over a range of two hundred miles), an array of prohibitive size would be required.
German language
German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....
for "ultra-short-wave landing radio beacon", or LFF. Prior to the World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
the Germans had deployed the Lorenz blind-landing
Instrument Landing System
An instrument landing system is a ground-based instrument approach system that provides precision guidance to an aircraft approaching and landing on a runway, using a combination of radio signals and, in many cases, high-intensity lighting arrays to enable a safe landing during instrument...
aid at many airport
Airport
An airport is a location where aircraft such as fixed-wing aircraft, helicopters, and blimps take off and land. Aircraft may be stored or maintained at an airport...
s in and outside Germany, and equipped most of their bombers with the radio equipment needed to use it.
The basic idea behind the short-range LFF system was later developed into a long-range 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-Boat
U-boat
U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...
s 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.
Description
The blind approach navigation system was developed starting in 1932 by Dr. Ernst Kramar of the Lorentz AG company. It was adopted by Deutsche LufthansaDeutsche Luft Hansa
Deutsche Luft Hansa A.G. was a German airline, serving as flag carrier of the country during the later years of the Weimar Republic and throughout the Third Reich.-1920s:Deutsche Luft Hansa was founded on 6 January 1926 in Berlin...
in 1934 and sold around the world. The Lorentz company was founded in 1880 by Carl Lorenz and is now part of ITT
ITT Corporation
ITT Corporation is a global diversified manufacturing company based in the United States. ITT participates in global markets including water and fluids management, defense and security, and motion and flow control...
.
Lorenz used a single radio transmitter
Transmitter
In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...
at 38 MHz and three antennas
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
placed in a line parallel to the end of the runway
Runway
According to ICAO a runway is a "defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft." Runways may be a man-made surface or a natural surface .- Orientation and dimensions :Runways are named by a number between 01 and 36, which is generally one tenth...
. The center antenna was always powered, while the other two were switched on and off in turn, fed from a common signal. With two of the antennas powered, the presence of the third resulted in a "kidney" shaped broadcast pattern centered on one of the two "side" antennas. The broadcast was switched so that the left antenna, as seen looking toward the runway on approach, was turned on only briefly, sending a series of "dots" 1/8 of a second long repeating once a second. When the left antenna was switched off the signal was sent to the right antenna instead, broadcasting a series of 7/8th second long "dashes". 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 runway would tune his radio to the broadcast frequency and listen for the signal. If they heard a series of dots, they knew they were off the runway centerline to the left (the dot-sector) and had to turn to the right to line up with the runway. If they were off to the right, they would hear a series of dashes instead (the dash-sector), and turned left. Key to the easy operation of the system was an area in the middle where the two signals overlapped, where the dots of the one signal "filled in" the dashes of the other, resulting in a steady tone known as the equi-signal. By adjusting their path until they heard the equi-signal, the pilot could align their aircraft with the runway for landing.
Two small radio beacons were also used with Lorenz, one 300 m off the end of runway, the HEZ, and another 3 km away, the VEZ, also broadcast on 38 MHz and modulated at 1700 and 700 Hz, respectively. These signals were broadcast directly upward, and would be heard briefly as the aircraft flew over them. To approach the runway, the aircraft would fly to a published altitude and then use the main directional signals to line up with the runway and started flying toward it. When they flew over the VEZ they would start descending on a standard glide slope, continuing to land or abort at the HEZ depending on whether or not they could see the runway.
Lorenz could fly a plane down a straight line with relatively high accuracy, enough so that the aircraft could then find the runway visually in all but the worst conditions. However it required a fairly constant monitoring of the radio by the pilot, who would often also be tasked with talking to the local control tower
Control tower
A control tower, or more specifically an Air Traffic Control Tower , is the name of the airport building from which the air traffic control unit controls the movement of aircraft on and around the airport. Control towers are also used to control the traffic for other forms of transportation such...
. In order to ease the workload, Lorenz later introduced a cockpit indicator that could listen to the signals and display the direction to the runway centerline as an arrow telling the pilot which direction to turn. The indicator also included neon lamp
Neon lamp
A neon lamp is a miniature gas discharge lamp that typically contains neon gas at a low pressure in a glass capsule. Only a thin region adjacent to the electrodes glows in these lamps, which distinguishes them from the much longer and brighter neon tubes used for signage...
to indicate when the aircraft crossed over the marker beacons. Later derivatives of the system had signals of equal length in the pattern left-right-silence, to operate a visual indicator in the cabin.
The Lorenz system was similar to the Diamond-Dunmore equi-signal radio guidance system, developed by the US Bureau of Standards in the early 1930s.
Use for blind bombing
In the Second World War the Lorenz beam principle was used by the German LuftwaffeLuftwaffe
Luftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....
as the basis of a number of blind bombing aids, notably Knickebein ('crooked leg') and the X-Gerät ('X-Apparatus'), in their bombing offensive against English cities during the winter of 1940/41. X-Gerät was very similar to LFF, modifying it only slightly to be more highly directional and work over much longer distance. Using the same frequencies allowed their bomber
Bomber
A bomber is a military aircraft designed to attack ground and sea targets, by dropping bombs on them, or – in recent years – by launching cruise missiles at them.-Classifications of bombers:...
s to use the already-installed LFF receivers, although a second receiver was needed in order to pinpoint a single location.
These systems involved cross-beams of the same characteristics but on a different frequency, which would both enable the pilot to calculate his speed (from the time between crossing the Fore Cross Signal and crossing the Main Cross Signal), and indicate when he should drop his payload. The calculation was performed by a mechanical computer. Lorenz modified this system to create the Viktoria/Hawaii lateral guidance system for the V-2 rocket.
Allied jamming effort
When the Allies discovered the existence of the 'Knickebein' system, they rapidly jammed it, however the 'X-Gerät' was not successfully jammed for quite some time. A later innovation by the Germans was the 'Baedeker' or 'Taub' modification, which used supersonic modulation. This was so quickly jammed that the Germans practically gave up on the use of beam-bombing systems, with the exception of the 'FuGe 25A', which operated for a short time towards the end of Operation SteinbockOperation Steinbock
Operation Steinbock was the nocturnal Second World War Luftwaffe offensive operation to destroy British military and civilian targets in southern England, between January and May 1944. The attacks were mainly in and around the Greater London area...
, known as the "Baby Blitz".
A further operational drawback of the system was that bombers had to follow a fixed course between the beam transmitter station and the target; once the beam had been detected, defensive measures were made more effective by knowledge of the course.
Consol/Sonne After world war II
The long range version that was developed by the Germans during the war got used by many countries for civilian purposes after the war. Mostly under its English name Consol. Transmitters were installed in both the US, the UK and the USSR.Technical considerations
The reason why the Lorenz beam principle was necessary, with its overlapping beams, was because the sharpness of a beam increases approximately logarithmically with the length of the aerial array with which it is generated; a law of diminishing returnsDiminishing returns
In economics, diminishing returns is the decrease in the marginal output of a production process as the amount of a single factor of production is increased, while the amounts of all other factors of production stay constant.The law of diminishing returns In economics, diminishing returns (also...
operates, such that to attain the sharpness achieved by the Lorenz system with a single beam (approximately 1 mile wide over a range of two hundred miles), an array of prohibitive size would be required.
See also
- Battle of the beamsBattle of the beamsThe Battle of the Beams was a period early in the Second World War when bombers of the German Air Force used a number of increasingly accurate systems of radio navigation for night bombing. British "scientific intelligence" at the Air Ministry fought back with a variety of increasingly effective...
- Radio navigationRadio navigationRadio navigation or radionavigation is the application of radio frequencies to determine a position on the Earth. Like radiolocation, it is a type of radiodetermination.The basic principles are measurements from/to electric beacons, especially...
- Experimental Radio Station EberswaldeExperimental Radio Station EberswaldeThe Experimental Radio Station Eberswalde was an experimental radio station of the company Carl Lorenz founded in Eberswalde, Germany in 1909. It used an umbrella aerial, which was carried at a 70 metres high, guyed central mast and at the corners on 16 30 metres high timber masts, as antenna...
- Instrument landing systemInstrument Landing SystemAn instrument landing system is a ground-based instrument approach system that provides precision guidance to an aircraft approaching and landing on a runway, using a combination of radio signals and, in many cases, high-intensity lighting arrays to enable a safe landing during instrument...
- SCR-277SCR-277The SCR-277 was a mobile, trailer mounted radio range set for radio guidance of aircraft. It was standardized by the U.S. Army in June of 1941.-Specifications:...
External links
- http://www.sonne-consol.es