title: Point of no return

text: The first major metaphorical use of the term in popular culture was in the 1947 novel "Point of No Return" by John P. Marquand. It inspired a 1951 Broadway play of the same name by Paul Osborn. The novel and play concern a pivotal period in the life of a New York City banker. In the course of the story, the character faces two "point of no return" realities: first, that his quest for a big promotion will mean either triumph or a dead end to his career, and second, that he can never go back to the small-town life he abandoned as a young man.


title: Point of no return

text: The Point of Safe Return (PSR) is the last point on a route at which it is possible to safely return to the departure airfield with the required fuel reserves still available in the tanks. Continuing past the PSR, the aircraft must either land at its intended destination or divert and land at another nearby airfield should an emergency arise.


title: Opus number

text: In musicology, the opus number is the "work number" that is assigned to a musical composition, or to a set of compositions, to indicate the chronological order of the composer's production. Opus numbers are used to distinguish among compositions with similar titles; the word is abbreviated as "Op." for a single work, or "Opp." when referring to more than one work.


title: Opus number

text: To indicate the specific place of a given work within a music catalogue, the opus number is paired with a cardinal number; for example, Beethoven's Piano Sonata No. 14 in C-sharp minor (1801, nicknamed "Moonlight Sonata") is "Opus 27, No. 2", whose work-number identifies it as a companion piece to "Opus 27, No. 1" (Piano Sonata No. 13 in E-flat major, 1800–01), paired in same opus number, with both being subtitled "Sonata quasi una Fantasia", the only two of the kind in all of Beethoven's 32 piano sonatas. Furthermore, the "Piano Sonata, Op. 27 No. 2, in C-sharp minor" is also catalogued as "Sonata No. 14", because it is the fourteenth sonata composed by Ludwig van Beethoven.


title: Opus number

text: Given composers' inconsistent or inexistent assignment of opus numbers, especially during the Baroque (1600–1750) and the Classical (1750–1827) eras, musicologists have developed other catalogue-number systems; among them the "Bach-Werke-Verzeichnis" (BWV-number), and the "Köchel-Verzeichnis" (K- and KV-numbers) which enumerate the works of Johann Sebastian Bach and Wolfgang Amadeus Mozart, respectively.


title: Opus number

text: In the classical period, the Latin word "opus" ("work", "labour"), plural "opera", was used to identify, list, and catalogue a work of art.


title: Opus number

text: By the 15th and 16th centuries, the word "opus" was used by Italian composers to denote a specific musical composition, and by German composers for collections of music. In compositional practice, numbering musical works in chronological order dates from 17th-century Italy, especially Venice. In common usage, the word "opus" is used to describe the best work of an artist with the term "magnum opus".


title: Opus number

text: In Latin, the words "opus" (singular) and "opera" (plural) are related to the words "opera" (singular) and "operae" (plural), which gave rise to the Italian words "opera" (singular) and "opere" (plural), likewise meaning "work". In contemporary English, the word "opera" has specifically come to denote the dramatic musical genres of opera or ballet, which were developed in Italy. As a result, the plural "opera" of "opus" tends to be avoided in English. In other languages such as German, however, it remains common.


title: Opus number

text: In the arts, an opus number usually denotes a work of musical composition, a practice and usage established in the seventeenth century when composers identified their works with an opus number. In the eighteenth century, publishers usually assigned opus numbers when publishing groups of like compositions, usually in sets of three, six or twelve compositions. Consequently, opus numbers are not usually in chronological order, unpublished compositions usually had no opus number, and numeration gaps and sequential duplications occurred when publishers issued contemporaneous editions of a composer's works, as in the sets of string quartets by Joseph Haydn (1732–1809) and Ludwig van Beethoven (1770–1827); Haydn's Op. 76, the Erdödy quartets (1796–97), comprises six discrete quartets consecutively numbered Op. 76 No. 1 – Op. 76 No. 6; whilst Beethoven's Op. 59, the Rasumovsky quartets (1805–06), comprises String Quartet No. 7, String Quartet No. 8, and String Quartet No. 9.


title: Opus number

text: From about 1800, composers usually assigned an opus number to a work or set of works upon publication. After approximately 1900, they tended to assign an opus number to a composition whether published or not. However, practices were not always perfectly consistent or logical. For example, early in his career, Beethoven selectively numbered his compositions (some published without opus numbers), yet in later years, he published early works with high opus numbers. Likewise, some posthumously published works were given high opus numbers by publishers, even though some of them were written early in Beethoven's career. Since his death in 1827, the un-numbered compositions have been cataloged and labeled with the German acronym WoO ("Werk ohne Opuszahl"), meaning "work without opus number"; the same has been done with other composers who used opus numbers. (There are also other catalogs of Beethoven's works – see Catalogues of Beethoven compositions.)


title: Opus number

text: The practice of enumerating a posthumous opus ("Op. posth.") is noteworthy in the case of Felix Mendelssohn (1809–47); after his death, the heirs published many compositions with opus numbers that Mendelssohn did not assign. In life, he published two symphonies (Symphony No. 1 in C minor, Op. 11; and Symphony No. 3 in A minor, Op. 56), furthermore he published his symphony-cantata "Lobgesang", Op. 52, which was posthumously counted as his Symphony No. 2; yet, he chronologically wrote symphonies between symphonies Nos. 1 and 2, which he withdrew for personal and compositional reasons; nevertheless, the Mendelssohn heirs published (and cataloged) them as the " Italian" Symphony No. 4 in A major, Op. 90, and as the " Reformation" Symphony No. 5 in D major and D minor, Op. 107.


title: Opus number

text: While many of the works of Antonín Dvořák (1841–1904) were given opus numbers, these did not always bear a logical relationship to the order in which the works were written or published. To achieve better sales, some publishers, such as N. Simrock, preferred to present less experienced composers as being well established, by giving some relatively early works much higher opus numbers than their chronological order would merit. In other cases, Dvořák gave lower opus numbers to new works to be able to sell them to other publishers outside his contract obligations. This way it could happen that the same opus number was given to more than one of his works. Opus number 12, for example, was assigned, successively, to five different works (an opera, a concert overture, a string quartet, and two unrelated piano works). In other cases, the same work was given as many as three different opus numbers by different publishers. The sequential numbering of his symphonies has also been confused: (a) they were initially numbered by order of publication, not composition; (b) the first four symphonies to be composed were published after the last five; and (c) the last five symphonies were not published in order of composition. The "New World Symphony" originally was published as No. 5, later was known as No. 8, and definitively was renumbered as No. 9 in the critical editions published in the 1950s.


title: Opus number

text: Other examples of composers' historically inconsistent opus-number usages include the cases of César Franck (1822–1890), Béla Bartók (1881–1945), and Alban Berg (1885–1935), who initially numbered, but then stopped numbering their compositions. Carl Nielsen (1865–1931) and Paul Hindemith (1895–1963) were also inconsistent in their approaches. Sergei Prokofiev (1891–1953) was consistent and assigned an opus number to a composition "before" composing it; at his death, he left fragmentary and planned, but numbered, works. In revising a composition, Prokofiev occasionally assigned a new opus number to the revision; thus Symphony No. 4 is two thematically related but discrete works: Symphony No. 4, Op. 47, written in 1929; and Symphony No. 4, Op. 112, a large-scale revision written in 1947. Likewise, depending upon the edition, the original version of Piano Sonata No. 5 in C major, is cataloged both as Op. 38 and as Op. 135.


title: Opus number

text: Despite being used in more or less normal fashion by a number of important early-twentieth-century composers, including Arnold Schoenberg (1874–1951) and Anton Webern (1883–1945), opus numbers became less common in the later part of the twentieth century.


title: Opus number

text: To manage inconsistent opus-number usages — especially by composers of the Baroque (1600–1750) and of the Classical (1720—1830) music eras — musicologists have developed comprehensive and unambiguous catalogue number-systems for the works of composers such as:


title: McLaren MCL36

text: The McLaren MCL36 is a Formula One car designed under the lead of James Key and manufactured by McLaren to compete in the 2022 Formula One World Championship. The MCL36 was built to the new 2022 generation of Formula One technical regulations, which were originally intended for introduction in .


title: McLaren MCL36

text: The car made its début at the 2022 Bahrain Grand Prix, and was driven by Daniel Ricciardo and Lando Norris in their second and fourth year for the team, respectively. The car achieved two fastest laps and one podium finish over the course of the season, both scored by Norris. The MCL36 was the only car (and Norris the only driver) from outside the top three teams to finish on the podium in the 2022 season.


title: McLaren MCL36

text: McLaren's switch to Mercedes engines was meant to coincide with the new technical regulations and was therefore contracted for 2021. Planning for the new regulations started in early 2019 and active development of the car started in 2020 before the 2021 regulations change was postponed. This postponement was intended to reduce financial pressures on teams due to the COVID-19 pandemic, while teams' 2020 chassis were to be reused in 2021. Hence, McLaren's switch to Mercedes power units occurred with the MCL36's predecessor, the MCL35M.


title: McLaren MCL36

text: Aerodynamic development of all teams' 2022 cars was paused from 28 March 2020 until 31 December 2020 because of the postponement of the regulatory change. McLaren restarted development in early January 2021 with aerodynamic testing. Manufacturing of some components, mainly chassis and gearbox parts, was underway by July 2021.


title: McLaren MCL36

text: Key was originally hired by McLaren from Toro Rosso in early 2019, when the MCL34 had already been designed and manufactured. Although he designed the MCL35 and the MCL35M upgrade, the MCL36 will be Key's first completely original car for the team. Key has called the development of the 2022 car's larger and less intricate surfaces a significant departure from the more specific and detailed development allowed in previous years.


title: McLaren MCL36

text: By October 2021, the car was being run on the McLaren simulator. Norris termed it "not as nice" to drive, but was hesitant to draw conclusions before the physical car was complete given the rapid progress in 2022 designs. The chassis passed FIA homologation tests in early December 2021. Key stated that McLaren's primary goal was to produce a more balanced car that performed better in low-speed corners compared to the MCL35 and MCL35M, both of which lacked low-speed performance despite good high-speed cornering.


title: McLaren MCL36

text: At its launch, the car was noted for its conventional tight packaging of the engine and its reversing of the typical suspension layout: the MCL36 features pull-rod front suspension and push-rod rear suspension, a layout not seen in Formula One since on the MP4-28. This change maximises the downforce produced by the Venturi and ground effects by allowing unimpeded airflow in and out of the car's air inlets, increasing the volume of air moved through the floor. The floor features an L-shaped edge wing and a ridged unnderfloor which was emulated by other teams, most notably on the Ferrari F1-75.


title: McLaren MCL36

text: The MCL36 features more vibrant, fluorescent shades of papaya orange and blue. The change was inspired after the MCL35M's one-off Gulf livery, featuring similar shades, received a very positive fan reaction.


title: McLaren MCL36

text: McLaren introduced a special livery in collobaration with sponsor OKX for the Singapore and Japanese Grands Prix. The livery featured new cyberpunk-themed illustrations and replaced the blue highlights with neon pink.


title: McLaren MCL36

text: A second special livery was used for the Abu Dhabi Grand Prix in collaboration with Vuse. As with the livery for the previous year's race, the car featured the artwork of an emerging artist, Lebanese artist Anna Tangles.


title: McLaren MCL36

text: During the first three-day test at Circuit de Barcelona-Catalunya, many teams experienced porpoising on their cars (resonation of the car due to the ground effect, making the car rock rapidly) which posed a driveability and reliability issue. Uniquely, the MCL36 did not appear to exhibit any issues with porpoising, although Key said "We suffer from it a bit, but it's not a major concern or a major distraction for the drivers." The lack of porpoising was partly linked to the MCL36's edge wing (an aerodynamic component on the outer edge of the car's floor). The solution was copied by several other teams over the course of the season.


title: McLaren MCL36

text: After the first round of testing, the car was generally expected to be competitive and allow McLaren to join a group of front-running teams. However, the second test at Bahrain International Circuit in higher temperatures exposed an issue with the MCL36's brakes, preventing the team from completing any long-run tests. Ricciardo tested positive to COVID-19 and was required to isolate, preventing him from completing any of his test program and leaving Norris to complete the test alone. The team said they had been unable to "do any optimization" to the car at the Bahrain test.


title: McLaren MCL36

text: McLaren introduced an "interim solution" to its front brake issues for the Bahrain Grand Prix. The team was disappointed in its performance, as neither car made it to the final stage of qualifying: Norris qualified thirteenth and Ricciardo eighteenth. Key said the car was performing as the team expected and the drivers were finding it a more consistent and predictable car, but that the MCL36 lacked aerodynamic and mechanical grip. Ricciardo finished fourteenth and Norris fifteenth. Ricciardo stated that he had treated the race as a test session in an attempt to recover time he had lost in the pre-season test. The result placed the team ninth in the Constructors' Championship (WCC).


title: McLaren MCL36

text: No upgrades were made to the car at the Saudi Arabian Grand Prix, as parts were delayed to prioritise the front brake cooling solution. Norris qualified eleventh and Ricciardo twelfth, but the latter started fourteenth after receiving a grid penalty. Norris finished seventh, battling for sixth place on the final lap. Ricciardo did not finish the race, retiring with undiagnosed mechanical issues. Norris improved to tenth and Ricciardo fell to nineteenth in the Drivers' Championship (WDC), while the team improved to eighth in the WCC.


title: McLaren MCL36

text: The team introduced an aerodynamic upgrade to the area around the rear brakes for the Australian Grand Prix, to improve the wake produced by the tyres and diffuser. Norris qualified fourth and Ricciardo qualified seventh, and finished fifth and sixth, respectively. The team improved to fourth in the WCC, and Norris to eighth and Ricciardo to eleventh in the WDC.


title: McLaren MCL36

text: The MCL36 featured a new beam wing for the Emilia Romagna Grand Prix. Qualifying was wet, and Norris qualified third and Ricciardo sixth for the sprint. The drivers finished the sprint in fifth and sixth respectively. The race started in wet conditions, and out of the second corner, Ricciardo understeered into Sainz, ending the latter's race. Ricciardo finished eighteenth. Norris made his way back up to third by the end of the first lap, but was overtaken by Leclerc and ran in fourth for most of the race, managing his gap to fifth place comfortably. In the closing laps, Leclerc bounced over a curb and had a mild collision with the barriers, allowing Norris to inherit third place. Norris improved to sixth in the WDC. The MCL36 was the only car (and Norris the only driver) from outside the top three teams (Red Bull, Ferrari, and Mercedes) to finish on the podium in the 2022 season.


title: McLaren MCL36

text: The car's front suspension was strengthened for reliability and an additional floor stay was added to minimise porpoising in upgrades introduced at the Miami Grand Prix. Norris qualified eighth and Ricciardo fourteenth for the race. During the race, Norris was involved in a collision with Pierre Gasly whose AlphaTauri AT03 had suffered steering damage. Both retired from the race. Ricciardo finished eleventh but was demoted to thirteenth by a time penalty for overtaking off-track. Norris fell to seventh in the WDC.


title: McLaren MCL36

text: McLaren introduced a total of ten upgrades for the Spanish Grand Prix, which consisted of changes to various aerodynamic parts, brakes, and suspension. Ricciardo qualified ninth, and Norris, who lost a lap time due to a track limits violation, qualified eleventh. Norris, despite suffering from tonsillitis, finished eighth. Ricciardo finished twelfth.


title: McLaren MCL36

text: At the Monaco Grand Prix, McLaren ran the car with extra cooling on the front brakes and different steering geometry and rear-view mirrors to account for the nature of the Circuit de Monaco. Norris and Ricciardo qualified fifth and fourteenth respectively. In a rain affected race, Norris finished sixth and set the fastest lap, and Ricciardo finished twelfth.


title: McLaren MCL36

text: The MCL36 was run with a track-specific aero kit to reduced load and more cooling options for the Azerbaijan Grand Prix. Norris qualified for the race eleventh and Ricciardo twelfth, and finished ninth and eighth respectively. Team orders were used twice in the race, first to keep Ricciardo behind Norris in the early stages and then to keep Norris behind Ricciardo in the final laps. The team's strategy was criticized for being ineffective and compromising both drivers' pace. Ricciardo fell to thirteenth in the WDC.


title: McLaren MCL36

text: For the Canadian Grand Prix, McLaren updated the rear wing assembly for aerodynamic efficiency and changed the location of the floor stay for better stiffness. Norris suffered a power unit issue during qualifying which prevented him from setting a time in the second stage. He started fourteenth, while Ricciardo qualified ninth. During the first virtual safety car, Ricciardo was ninth and Norris twelfth, when McLaren attempted to double-stack a pit stop. After a slow stop for Ricciardo, the pit crew fitted the wrong tyres to Norris's car before correcting the mistake. Ricciardo exited twelfth and Norris eighteenth, and they finished eleventh and fifteenth respectively after both cars suffered brake issues in the final stages of the race.


title: McLaren MCL36

text: McLaren announced ahead of the British Grand Prix that the MCL36 would not receive further major upgrades due to the budget cap. Instead, only minor technical updates would be provided. Norris qualified for the race sixth; and held fifth in the race until losing the position in the pits during the final safety car, finishing sixth. Ricciardo qualified fourteenth, but started twelfth after the red flag caused by Zhou Guanyu's first lap incident. A failure of the drag reduction system on his MCL36 necessitated an extra stop, and Ricciardo finished the race thirteenth. The result dropped Ricciardo to fourteenth in the WDC.


title: McLaren MCL36

text: The car featured revised brake ducts and rear wing endplates beginning with the Austrian Grand Prix. Norris suffered an engine failure in the first practice session and reverted to an older engine for the rest of the weekend. He also experienced brake issues during qualifying, and he qualified fifteenth and Ricciardo sixteenth for the second sprint of the season. The two finished eleventh and twelfth respectively in the sprint, which became tenth and eleventh on the starting grid after penalties were applied for other drivers. During the race Norris was awarded a time penalty for exceeding track limits, a penalty he said cost him the chance to challenge for sixth place as he finished seventh. Ricciardo finished ninth. Ricciardo improved to twelfth in the WDC. Alpine drew level with McLaren in the WCC, but McLaren retained fourth place after the countback. McLaren remained at the Red Bull Ring after the race for a Pirelli tyre test, with Ricciardo and Norris both doing a day of testing of the 2023 tyre compounds.


title: McLaren MCL36

text: McLaren introduced another substantial upgrade package for the French Grand Prix, which featured a new diffuser, underfloor, rear brake ducts, and sidepods, as well as a change to the rear wing endplate for reliability. Most significantly, the shape of the sidepods changed dramatically. Throughout the turbo-hybrid era, teams pursued a narrow sidepod that exposed as much of the floor as possible, but the 2022 regulation changes limited this design concept's potential due to the primacy of the ground effect. The new MCL36 sidepods were similar to those featured on the title-challengers, the Ferrari F1-75 and Red Bull Racing RB18, with an emphasis on managing tyre wake and the introduction of a downwashing plane that delivers air to the rear of the car. The upgrade appeared effective in qualifying; Norris qualified fifth and Ricciardo eleventh. Ricciardo started ninth after grid penalties for two drivers ahead of him, and finished the race in ninth place. Norris had a poor start, and finished seventh. The result cost McLaren fourth in the WCC, and they fell to fifth behind Alpine.


title: McLaren MCL36

text: Beginning with the Hungarian Grand Prix, the MCL36 featured revised front brake cooling system and new underfloor flow conditioners designed to better engage the diffuser. Norris qualified fourth and Ricciardo ninth. Norris finished seventh and Ricciardo finished thirteenth, but was demoted to fifteenth by a five-second penalty awarded for causing a collision with Lance Stroll.


title: McLaren MCL36

text: An extensive list of updates débuted at the Belgian Grand Prix. This package included a low-drag rear wing, beam wing, and rear corner assembly, an updated diffuser and floor assembly, new front suspension track rods and a new winglet in the rear corner, and a streamlined circuit-specific engine cover. The overall aim of the package was to improve aerodynamic efficiency and maximise straight-line speed to take advantage of the low downforce requirements of Circuit de Spa-Francorchamps. Norris qualified tenth, but was relegated to seventeenth on the grid due as the team exceeded the number of allowable power unit components. Ricciardo qualified eleventh, but was promoted to seventh on the grid due to penalties for other drivers. Both drivers were caught in DRS trains. Norris finished the race twelfth and Ricciardo fifteenth, resulting in Ricciardo falling from twelfth to thirteenth in the WDC.


title: McLaren MCL36

text: At the Dutch Grand Prix, Norris qualified and finished in seventh, and Ricciardo qualified and finished in seventeenth.


title: McLaren MCL36

text: The car was run in a low-downforce specification for the Italian Grand Prix. Norris and Ricciardo qualified seventh and eighth respectively, which became third and fourth respectively once grid penalties were applied to other drivers. The clutch map on Norris's MCL36 failed at the race start, forcing him to launch the car manually and costing him several positions on the first lap. He finished seventh, while Ricciardo retired after an oil leak caused a failure on his Mercedes engine. The race result meant Ricciardo moved from thirteenth to fourteenth in the WDC.


title: McLaren MCL36

text: The MCL36 featured a special livery for the Singapore Grand Prix (see ). McLaren also delivered a substantial upgrade, designed to deliver performance in a conceptually new way, partly in preparation for . The package was initially given only to Norris due to a shortage of parts. Aerodynamically, the upgrade included new radiator inlet and floor designs, and again shifted the sidepod design closer to that of the RB18. Internal packaging of the radiators, cooling systems, electronics, and side impact spars was also rearranged. Norris qualified sixth and Ricciardo qualified sixteenth. In a wet-to-dry race, Norris moved up to fourth and Ricciardo to fifth. McLaren took fourth place in the WCC from Alpine, while Ricciardo moved up to eleventh in the WDC.


title: McLaren MCL36

text: The car again featured the special livery for the Japanese Grand Prix (see ). The upgrades introduced to Norris's car in Singapore were added to Ricciardo's MCL36. Norris qualified in tenth and Ricciardo in eleventh, and both finished in those same places in the race, which was shortened by heavy rain. The team lost fourth place to Alpine in the WCC, and Ricciardo fell to twelfth in the WDC.


title: McLaren MCL36

text: 2021 IndyCar champion Álex Palou replaced Ricciardo for the first practice session at the United States Grand Prix, fulfilling the first of two mandatory rookie practice sessions. Both Ricciardo and Norris took part in Pirelli's 2023 tyre test in the second practice session. Norris qualified eighth and Ricciardo qualified seventeenth, but penalties for other drivers promoted Norris to sixth and Ricciardo to sixteenth. During the race, Norris's car was struck by debris from a separate incident; after the safety car ended he pitted from ninth place and rejoined the track thirteenth, but finished sixth. Ricciardo finished sixteenth.


title: McLaren MCL36

text: McLaren added several track-specific features to the MCL36 at the Mexico City Grand Prix, namely an extensive cooling package and extra winglets on the rear brake ducts to improve downforce. Norris qualified eighth, and Ricciardo qualified eleventh. Ricciardo collided with Yuki Tsunoda and was issued with a ten-second penalty, but was one of few drivers who switched from medium to soft tyres to finish seventh, even after the penalty was applied. Norris, who was on the medium to hard strategy, finished ninth.


title: McLaren MCL36

text: Norris fell ill before the São Paulo Grand Prix, prompting McLaren to prepare Nyck de Vries as a replacement. Norris was however able to participate in the weekend, qualifying fourth for the final sprint of the season, while Ricciardo qualified fourteenth. Norris finished seventh in the sprint, but started the race sixth after penalties for other drivers, while Ricciardo finished eleventh. Ricciardo collided with Kevin Magnussen on the opening lap, which caused both to retire from the race and for Ricciardo to be awarded a three-place grid penalty for the next race. The incident also required a safety car, and after the restart Norris collided with Leclerc. Although both continued the race, Norris was awarded a five-second time penalty, although he also retired from the race with electrical issues. McLaren lost fourth to Alpine in the WCC.


title: McLaren MCL36

text: The car featured a second special livery for the Abu Dhabi Grand Prix (see ). Arrow McLaren SP IndyCar driver Pato O'Ward replaced Norris for the first practice session, fulfilling the second of the two mandatory rookie practice sessions. The team tested a new floor as part of the development program for their car during free practice. Norris qualified seventh and Ricciardo qualified tenth, but the later was demoted to thirteenth on the starting grid due to his penalty from the previous race. Norris finished sixth and set the fastest lap of the race, and Ricciardo finished ninth. McLaren finished the season fifth in the WCC, while Norris finished seventh and Ricciardo eleventh in the WDC.


title: McLaren MCL36

text: The MCL36 remained at Yas Marina Circuit following the Abu Dhabi Grand Prix to be used in the annual post-season test. Oscar Piastri, who replaced Ricciardo for 2023, participated in the test after Alpine agreed to release Piastri from his contract early. Piastri drove the car as run in the season and completed 123 laps, while Norris tested the 2023 Pirelli compounds over 115 laps.


title: McLaren MCL36

text: Both drivers stated that the MCL36 did not suit their driving style or provide the characteristics they thought desirable in a racing car. Norris stated that braking and cornering could be inconsistent, even from corner to corner and that the car did not perform consistently across different circuits. This inconsistency was primarily attributed to an aerodynamically weak front end, particularly noticeable in slow-speed corners.


title: McLaren MCL36

text: The MCL36 did appear to be aerodynamically efficient at tracks with lower downforce requirements and experienced very little porpoising. The car generally seemed competitive over a single lap in qualifying, but suffered over the course of a full race distance. This was largely credited to the car's effectiveness in heating the Pirelli tyres to their operating window, tempered by its difficulty to preserve them over longer distances.


title: Comerica Park

text: Comerica Park is a baseball stadium located in Downtown Detroit. It has been the home of Major League Baseball's Detroit Tigers since 2000, when the team left Tiger Stadium.


title: Comerica Park

text: Founded in 1894, the Tigers had played at the corner of Michigan and Trumbull Avenues in Detroit's Corktown neighborhood since 1896, when Bennett Park opened. In 1911, new Tigers owner Frank Navin ordered the construction of a new ballpark to be built on the same site. Opening in 1912, the ballpark, which eventually became known as Tiger Stadium, served as the Tigers' home for the next 88 seasons. By the mid-1990s, it had become apparent that the much-beloved ballpark had become obsolete and could not be renovated any further.


title: Comerica Park

text: Comerica Park sits on the original site of the Detroit College of Law. Groundbreaking for the new stadium was held on October 29, 1997. At the time of construction, the scoreboard in left field was the largest in Major League Baseball. It was part of a downtown revitalization plan for the city of Detroit, which included the construction of Ford Field, adjacent to the ballpark. The first game was held on April 11, 2000, against the Seattle Mariners.


title: Comerica Park

text: The first game at Comerica Park was held on Tuesday, April 11, 2000, with 39,168 spectators attending, on a cold snowy afternoon. The temperature that afternoon was . The Tigers beat the Seattle Mariners 5–2. The winning pitcher, as in the final game at Tiger Stadium, was Brian Moehler.


title: Comerica Park

text: In December 1998, Comerica Bank agreed to pay $66 million over 30 years for the naming rights for the new ballpark. In 2018, Comerica extended its naming rights agreement with the Tigers through 2034.


title: Comerica Park

text: The main entrance to the ballpark is located across the street from the Fox Theatre and between two historic downtown churches, St. John Episcopal Church and Central United Methodist Church. Outside the main entrance is a tiger statue that is in height. There are 8 other heroic-sized tiger statues throughout the park, including two prowling on top of the scoreboard in left field. These tigers' eyes light up after a Tigers home run or a victory and the sound of a growling tiger plays as well. The tigers were originally created by sculptor Michael Keropian and fabricated by ShowMotion Inc. in Norwalk, Connecticut. Along the brick walls outside the park are 33 tiger heads with lighted baseballs in their mouths.


title: Comerica Park

text: At the left-center field concourse there are statues of almost all of the players whose numbers have been retired by the Tigers (with the exception of Jackie Robinson, whose number was retired in every MLB park in 1997 and is located on the wall in right-center field). A statue of Ty Cobb is also there, but he does not have a number, as he played baseball before players began to wear numbers on their uniforms. These players' names, along with the names of Hall of Fame players and broadcasters who spent a significant part of their career with the Tigers, are also on a wall in right-center field. Ernie Harwell, the team's long time radio announcer and a recipient of the Hall of Fame's Ford C. Frick Award, has a statue just inside the stadium on the first base side.


title: Comerica Park

text: Comerica Park is currently the only ballpark in MLB to feature a distinctive dirt strip between home plate and the pitcher's mound. This strip, sometimes known as the "keyhole", was common in early ballparks, but it is very rare in modern facilities. Additionally, the home plate area is in the shape of the home plate itself, and not as a standard circle.


title: Comerica Park

text: In the northeastern corner of the stadium behind the stands from the third base line is a Ferris wheel with twelve cars designed like baseballs. In the northwestern corner of the stadium behind the stands from the first base line is a carousel.


title: Comerica Park

text: The flagpole located between center and left fields was originally in play, as was the flagpole in Tiger Stadium. However, the left field wall was moved in front of the pole before the 2003 season. A ball that hits the pole is now ruled a home run. The right field of the stadium features the Pepsi Porch, a picnic deck between the 100 and 200 level seating bowls. Also in right field, and part of the 100 level seating bowl, is an area of seats known as "Kaline's Corner", an homage to Hall of Fame right fielder Al Kaline, who once played for the Tigers when the team played in Tiger Stadium.


title: Comerica Park

text: An LED scoreboard was added to the right-center field wall, and the upper deck fascia for the 2007 season.


title: Comerica Park

text: A giant fountain is located behind center field. General Motors sponsored the fountain from 2000 to 2008, and used the area to showcase GM manufactured vehicles as well. While GM dropped its sponsorship for the 2009 season due to financial issues, the GM branding was not removed from the fountain. Instead, signs for Chrysler and Ford were also added to the display, along with the message "The Detroit Tigers support our automakers." In 2010, GM returned to sponsoring the display, now known as the Chevrolet Fountain.


title: Comerica Park

text: A completely redesigned and upgraded left field video display debuted for the 2012 season. The serif "TIGERS" wordmark was removed and replaced by cursive lettering that can also display graphics and video. An analog clock below the Tigers wordmark and above the Comerica Park logo was also removed. An HD LED display was installed, which was much larger than the three displays that had been there for years. The previous scoreboard used light bulbs – still a popular scoreboard technology around the time the park opened, though they were quickly aging as LED displays became available and were installed around other Major League ballparks. The scoreboard was also raised in an effort to address complaints that the scoreboard was too far left and thus obstructed by the left field upper deck. Along with the replacement scoreboard, all remaining bulb fascia scoreboards were also upgraded to LED.


title: Comerica Park

text: In 2014, the Tigers announced a $4 million renovation to Comerica Park's Pepsi Porch. This renovation included the removal of the bleachers that once occupied the space and the addition of new stadium seats. The plan also included new high top tables, a new bar in the middle of the porch, couches and lounge chairs, as well as a fire pit. The bleachers that once occupied the area were moved to the space above The Jungle restaurant and bar.


title: Comerica Park

text: In contrast to Tiger Stadium, which had long been considered one of the most hitter-friendly parks in baseball, Comerica Park is considered to be extremely friendly to pitchers. Except for dead center field—420 feet (128 m) versus Tiger Stadium's 440 feet (134 m)—the outfield dimensions were more expansive than those at Tiger Stadium. This led to complaints from players and fans alike. Most famously, Bobby Higginson sarcastically referred to the venue as "Comerica National Park".


title: Comerica Park

text: Before the start of the 2003 MLB season, the club moved the distance from left-center field from . This also removed the flagpole from the field of play, originally incorporated as an homage to Tiger Stadium. Two years later, the bullpens were moved from right field to an empty area in left field created when the fence was moved in. In place of the old bullpens in right field, about 950 seats were added. This made one of the most pitcher-friendly ballparks transform into the third most batter-friendly (with extra bases also taken into account).


title: Comerica Park

text: In the layout of the playing field at Comerica Park, when a player is at bat, the direction he is facing looks farther to the south than at any other ballpark.


title: Comerica Park

text: Public transportation for the park is available via the Detroit People Mover station at Grand Circus Park and the QLine at the Montcalm Street station, in addition to SMART, which runs regional routes from the suburbs, and DDOT.


title: Comerica Park

text: In 2005, Comerica Park hosted the 76th MLB All-Star Game, the first to be played in Detroit since 1971. In the Home Run Derby, held the day before, Bobby Abreu slammed 24 home runs in the first round, breaking the previous record of 15. Abreu won the Derby over Tiger Iván Rodríguez, hitting a then record 41 homers during the event. In the All-Star Game, the American League won 7–5 with Miguel Tejada winning the game's MVP Award.


title: Comerica Park

text: The first playoff game at Comerica Park was played on October 6, 2006 against the New York Yankees. On October 21, 2006, Comerica Park hosted the first World Series game in the history of the ballpark (Game 1 of the 2006 World Series).


title: Comerica Park

text: On June 12, 2007, the first no-hitter was thrown at Comerica Park by Justin Verlander. The Tigers won the game 4–0 against the Milwaukee Brewers. It was also the first no-hitter thrown by a Tiger in the city of Detroit since Virgil Trucks accomplished the feat in 1952.


title: Comerica Park

text: In 2008, the Tiger statue at the main entrance of the ballpark was dressed with a Detroit Red Wings jersey as the Red Wings were playing against the Pittsburgh Penguins in the Stanley Cup Finals. The jersey is usually worn by the Spirit of Detroit, but it was undergoing restoration during that time.


title: Comerica Park

text: On August 15, 2011, Minnesota Twins slugger Jim Thome became the eighth player in baseball history to hit 600 career home runs.


title: Comerica Park

text: Comerica Park hosted its second World Series in 2012, with the Tigers getting swept by the San Francisco Giants.


title: Comerica Park

text: On April 23, 2022, Tigers slugger Miguel Cabrera became the 33rd player in Major League history to get his 3,000th hit with a single in the first inning off of Colorado Rockies pitcher Antonio Senzatela.


title: Comerica Park

text: On February 9, 2012, NHL commissioner Gary Bettman announced that Comerica Park would host the Hockeytown Winter Festival in concert with the 2013 NHL Winter Classic held at Michigan Stadium. The festival was to include events such as games between teams in the Ontario Hockey League, the American Hockey League, the Great Lakes Invitational, youth hockey games, and the NHL alumni game. Due to the 2012–13 NHL lockout, the festival was cancelled. The festival was rescheduled for December 2013. An outdoor rink was set up on the infield of the ballpark for public skating and hockey games.


title: Comerica Park

text: On July 19, 2017, Comerica Park hosted its first ever soccer game between Roma of the Italian Serie A League against Paris Saint-Germain of France's Ligue 1 in the 2017 International Champions Cup tournament.


title: History of radar

text: The history of radar (where radar stands for radio detection and ranging) started with experiments by Heinrich Hertz in the late 19th century that showed that radio waves were reflected by metallic objects. This possibility was suggested in James Clerk Maxwell's seminal work on electromagnetism. However, it was not until the early 20th century that systems able to use these principles were becoming widely available, and it was German inventor Christian Hülsmeyer who first used them to build a simple ship detection device intended to help avoid collisions in fog (Reichspatent Nr. 165546).


title: History of radar

text: True radar, such as the British Chain Home early warning system provided directional information to objects over short ranges, were developed over the next two decades.


title: History of radar

text: The development of systems able to produce short pulses of radio energy was the key advance that allowed modern radar systems to come into existence. By timing the pulses on an oscilloscope, the range could be determined and the direction of the antenna revealed the angular location of the targets. The two, combined, produced a "fix", locating the target relative to the antenna. In the 1934–1939 period, eight nations developed independently, and in great secrecy, systems of this type: the United Kingdom, Germany, the United States, the USSR, Japan, the Netherlands, France, and Italy. In addition, Britain shared their information with the United States and four Commonwealth countries: Australia, Canada, New Zealand, and South Africa, and these countries also developed their own radar systems. During the war, Hungary was added to this list. The term "RADAR" was coined in 1939 by the United States Signal Corps as it worked on these systems for the Navy.


title: History of radar

text: Progress during the war was rapid and of great importance, probably one of the decisive factors for the victory of the Allies. A key development was the magnetron in the UK, which allowed the creation of relatively small systems with sub-meter resolution. By the end of hostilities, Britain, Germany, the United States, the USSR, and Japan had a wide variety of land- and sea-based radars as well as small airborne systems. After the war, radar use was widened to numerous fields including: civil aviation, marine navigation, radar guns for police, meteorology and even medicine. Key developments in the post-war period include the travelling wave tube as a way to produce large quantities of coherent microwaves, the development of signal delay systems that led to phased array radars, and ever-increasing frequencies that allow higher resolutions. Increases in signal processing capability due to the introduction of solid state computers has also had a large impact on radar use.


title: History of radar

text: The place of radar in the larger story of science and technology is argued differently by different authors. On the one hand, radar contributed very little to theory, which was largely known since the days of Maxwell and Hertz. Therefore, radar did not advance science, but was simply a matter of technology and engineering. Maurice Ponte, one of the developers of radar in France, states:


title: History of radar

text: But others point out the immense practical consequences of the development of radar. Far more than the atomic bomb, radar contributed to the Allied victory in World War II. Robert Buderi states that it was also the precursor of much modern technology. From a review of his book:


title: History of radar

text: In 1886–1888 the German physicist Heinrich Hertz conducted his series of experiments that proved the existence of electromagnetic waves (including radio waves), predicted in equations developed in 1862–4 by the Scottish physicist James Clerk Maxwell. In Hertz's 1887 experiment he found that these waves would transmit through different types of materials and also would reflect off metal surfaces in his lab as well as conductors and dielectrics. The nature of these waves being similar to visible light in their ability to be reflected, refracted, and polarized would be shown by Hertz and subsequent experiments by other physicists.


title: History of radar

text: Radio pioneer Guglielmo Marconi noticed radio waves were being reflected back to the transmitter by objects in radio beacon experiments he conducted on March 3, 1899 on Salisbury Plain. In 1916 he and British engineer Charles Samuel Franklin used short-waves in their experiments, critical to the practical development of radar. He would relate his findings 6 years later in a 1922 paper delivered before the Institution of Electrical Engineers in London:


title: History of radar

text: In 1904, Christian Hülsmeyer gave public demonstrations in Germany and the Netherlands of the use of radio echoes to detect ships so that collisions could be avoided. His device consisted of a simple spark gap used to generate a signal that was aimed using a dipole antenna with a cylindrical parabolic reflector. When a signal reflected from a ship was picked up by a similar antenna attached to the separate coherer receiver, a bell sounded. During bad weather or fog, the device would be periodically spun to check for nearby ships. The apparatus detected the presence of ships up to , and Hülsmeyer planned to extend its capability to . It did not provide range (distance) information, only warning of a nearby object. He patented the device, called the "telemobiloscope", but due to lack of interest by the naval authorities the invention was not put into production.


title: History of radar

text: Hülsmeyer also received a patent amendment for estimating the range to the ship. Using a vertical scan of the horizon with the "telemobiloscope" mounted on a tower, the operator would find the angle at which the return was the most intense and deduce, by simple triangulation, the approximate distance. This is in contrast to the later development of pulsed radar, which determines distance via two-way transit time of the pulse.


title: History of radar

text: In 1915, Robert Watson Watt joined the Meteorological Office as a meteorologist, working at an outstation at Aldershot in Hampshire. Over the next 20 years, he studied atmospheric phenomena and developed the use of radio signals generated by lightning strikes to map out the position of thunderstorms. The difficulty in pinpointing the direction of these fleeting signals using rotatable directional antennas led, in 1923, to the use of oscilloscopes in order to display the signals. The operation eventually moved to the outskirts of Slough in Berkshire, and in 1927 formed the Radio Research Station (RRS), Slough, an entity under the Department of Scientific and Industrial Research (DSIR). Watson Watt was appointed the RRS Superintendent.


title: History of radar

text: As war clouds gathered over Britain, the likelihood of air raids and the threat of invasion by air and sea drove a major effort in applying science and technology to defence. In November 1934, the Air Ministry established the Committee for the Scientific Survey of Air Defence (CSSAD) with the official function of considering "how far recent advances in scientific and technical knowledge can be used to strengthen the present methods of defence against hostile aircraft". Commonly called the "Tizard Committee" after its Chairman, Sir Henry Tizard, this group had a profound influence on technical developments in Britain.


title: History of radar

text: H. E. Wimperis, Director of Scientific Research at the Air Ministry and a member of the Tizard Committee, had read about a German newspaper article claiming that the Germans had built a death ray using radio signals, accompanied by an image of a very large radio antenna. Both concerned and potentially excited by this possibility, but highly skeptical at the same time, Wimperis looked for an expert in the field of radio propagation who might be able to pass judgement on the concept. Watt, Superintendent of the RRS, was now well established as an authority in the field of radio, and in January 1935, Wimperis contacted him asking if radio might be used for such a device. After discussing this with his scientific assistant, Arnold F. 'Skip' Wilkins, Wilkins quickly produced a back-of-the-envelope calculation that showed the energy required would be enormous. Watt wrote back that this was unlikely, but added the following comment: "Attention is being turned to the still difficult, but less unpromising, problem of radio detection and numerical considerations on the method of detection by reflected radio waves will be submitted when required".


title: History of radar

text: Over the following several weeks, Wilkins considered the radio detection problem. He outlined an approach and backed it with detailed calculations of necessary transmitter power, reflection characteristics of an aircraft, and needed receiver sensitivity. He proposed using a directional receiver based on Watt's lightning detection concept, listening for powerful signals from a separate transmitter. Timing, and thus distance measurements, would be accomplished by triggering the oscilloscope's trace with a muted signal from the transmitter, and then simply measuring the returns against a scale. Watson Watt sent this information to the Air Ministry on February 12, 1935, in a secret report titled "The Detection of Aircraft by Radio Methods".


title: History of radar

text: Reflection of radio signals was critical to the proposed technique, and the Air Ministry asked if this could be proven. To test this, Wilkins set up receiving equipment in a field near Upper Stowe, Northamptonshire. On February 26, 1935, a Handley Page Heyford bomber flew along a path between the receiving station and the transmitting towers of a BBC shortwave station in nearby Daventry. The aircraft reflected the 6 MHz (49 m) BBC signal, and this was readily detected by Arnold "Skip" Wilkins using Doppler-beat interference at ranges up to . This convincing test, known as the "Daventry Experiment", was witnessed by a representative from the Air Ministry, and led to the immediate authorization to build a full demonstration system. This experiment was later reproduced by Wilkins for the 1977 BBC television series "The Secret War" episode "To See a Hundred Miles".


title: History of radar

text: Based on pulsed transmission as used for probing the ionosphere, a preliminary system was designed and built at the RRS by the team. Their existing transmitter had a peak power of about 1 kW, and Wilkins had estimated that 100 kW would be needed. Edward George Bowen was added to the team to design and build such a transmitter. Bowens’ transmitter operated at 6 MHz (50 m), had a pulse-repetition rate of 25 Hz, a pulse width of 25 μs, and approached the desired power.


title: History of radar

text: Orfordness, a narrow peninsula in Suffolk along the coast of the North Sea, was selected as the test site. Here the equipment would be openly operated in the guise of an ionospheric monitoring station. In mid-May 1935, the equipment was moved to Orfordness. Six wooden towers were erected, two for stringing the transmitting antenna, and four for corners of crossed receiving antennas. In June, general testing of the equipment began.


title: History of radar

text: On June 17, the first target was detected—a Supermarine Scapa flying boat at range. It is historically correct that, on June 17, 1935, radio-based detection and ranging was first demonstrated in Britain . Watson Watt, Wilkins, and Bowen are generally credited with initiating what would later be called radar in this nation.


title: History of radar

text: In December 1935, the British Treasury appropriated £60,000 for a five-station system called Chain Home (CH), covering approaches to the Thames Estuary. The secretary of the Tizard Committee, Albert Percival Rowe, coined the acronym RDF as a cover for the work, meaning Range and Direction Finding but suggesting the already well-known Radio Direction Finding.


title: History of radar

text: Late in 1935, responding to Lindemann's recognition of the need for night detection and interception gear, and realizing existing transmitters were too heavy for aircraft, Bowen proposed fitting only receivers, what would later be called bistatic radar. Frederick Lindemann's proposals for infrared sensors and aerial mines would prove impractical. It would take Bowen's efforts, at the urging of Tizard, who became increasingly concerned about the need, to see Air to Surface Vessel (ASV), and through it Airborne Interception (AI), radar to fruition.


title: History of radar

text: In 1937, Bowen's team set their crude ASV radar, the world's first airborne set, to detect the Home Fleet in dismal weather. Only in spring 1939, "as a matter of great urgency" after the failure of the searchlight system Silhouette, did attention turn to using ASV for air-to-air interception (AI). Demonstrated in June 1939, AI got a warm reception from Air Chief Marshal Hugh Dowding, and even more so from Churchill. This proved problematic. Its accuracy, dependent on the height of the aircraft, meant that CH, capable of only , was not accurate enough to place an aircraft within its detection range, and an additional system was required. Its wooden chassis had a disturbing tendency to catch fire (even with attention from expert technicians), so much so that Dowding, when told that Watson-Watt could provide hundreds of sets, demanded "ten that work". The Cossor and MetroVick sets were overweight for aircraft use and the RAF lacked night fighter pilots, observers, and suitable aircraft.


title: History of radar

text: In 1940, John Randall and Harry Boot developed the cavity magnetron, which made ten-centimetre ( wavelength ) radar a reality. This device, the size of a small dinner plate, could be carried easily on aircraft and the short wavelength meant the antenna would also be small and hence suitable for mounting on aircraft. The short wavelength and high power made it very effective at spotting submarines from the air.


title: History of radar

text: To aid Chain Home in making height calculations, at Dowding's request, the Electrical Calculator Type Q (commonly called the "Fruit Machine") was introduced in 1940.


title: History of radar

text: The solution to night intercepts would be provided by Dr. W. B. "Ben" Lewis, who proposed a new, more accurate ground control display, the Plan Position Indicator (PPI), a new Ground-Controlled Interception (GCI) radar, and reliable AI radar. The AI sets would ultimately be built by EMI. GCI was unquestionably delayed by Watson-Watt's opposition to it and his belief that CH was sufficient, as well as by Bowen's preference for using ASV for navigation, despite Bomber Command disclaiming a need for it, and by Tizard's reliance on the faulty Silhouette system.


title: History of radar

text: In March 1936, the work at Orfordness was moved to Bawdsey Manor, nearby on the mainland. Until this time, the work had officially still been under the DSIR, but was now transferred to the Air Ministry. At the new Bawdsey Research Station, the Chain Home (CH) equipment was assembled as a prototype. There were equipment problems when the Royal Air Force (RAF) first exercised the prototype station in September 1936. These were cleared by the next April, and the Air Ministry started plans for a larger network of stations.


title: History of radar

text: Initial hardware at CH stations was as follows: The transmitter operated on four pre-selected frequencies between 20 and 55 MHz, adjustable within 15 seconds, and delivered a peak power of 200 kW. The pulse duration was adjustable between 5 and 25 μs, with a repetition rate selectable as either 25 or 50 Hz. For synchronization of all CH transmitters, the pulse generator was locked to the 50 Hz of the British power grid. Four steel towers supported transmitting antennas, and four wooden towers supported cross-dipole arrays at three different levels. A goniometer was used to improve the directional accuracy from the multiple receiving antennas.


title: History of radar

text: By the summer of 1937, 20 initial CH stations were in check-out operation. A major RAF exercise was performed before the end of the year, and was such a success that £10,000,000 was appropriated by the Treasury for an eventual full chain of coastal stations. At the start of 1938, the RAF took over control of all CH stations, and the network began regular operations.


title: History of radar

text: In May 1938, Rowe replaced Watson Watt as Superintendent at Bawdsey. In addition to the work on CH and successor systems, there was now major work in airborne RDF equipment. This was led by E. G. Bowen and centered on 200-MHz (1.5 m) sets. The higher frequency allowed smaller antennas, appropriate for aircraft installation.


title: History of radar

text: From the initiation of RDF work at Orfordness, the Air Ministry had kept the British Army and the Royal Navy generally informed; this led to both of these forces having their own RDF developments.


title: History of radar

text: In 1931, at the Woolwich Research Station of the Army's Signals Experimental Establishment (SEE), W. A. S. Butement and P. E. Pollard had examined pulsed 600 MHz (50-cm) signals for detection of ships. Although they prepared a memorandum on this subject and performed preliminary experiments, for undefined reasons the War Office did not give it consideration.


title: History of radar

text: As the Air Ministry's work on RDF progressed, Colonel Peter Worlledge of the Royal Engineer and Signals Board met with Watson Watt and was briefed on the RDF equipment and techniques being developed at Orfordness. His report, "The Proposed Method of Aeroplane Detection and Its Prospects", led the SEE to set up an "Army Cell" at Bawdsey in October 1936. This was under E. Talbot Paris and the staff included Butement and Pollard. The Cell's work emphasize two general types of RDF equipment: gun-laying (GL) systems for assisting anti-aircraft guns and searchlights, and coastal- defense (CD) systems for directing coastal artillery and defense of Army bases overseas.


title: History of radar

text: Pollard led the first project, a gun-laying RDF code-named Mobile Radio Unit (MRU). This truck-mounted system was designed as a small version of a CH station. It operated at 23 MHz (13 m) with a power of 300 kW. A single tower supported a transmitting antenna, as well as two receiving antennas set orthogonally for estimating the signal bearing. In February 1937, a developmental unit detected an aircraft at a range of 60 miles (96 km). The Air Ministry also adopted this system as a mobile auxiliary to the CH system.


title: History of radar

text: In early 1938, Butement started the development of a CD system based on Bowen's evolving 200-MHz (1.5-m) airborne sets. The transmitter had a 400 Hz pulse rate, a 2-μs pulse width, and 50 kW power (later increased to 150 kW). Although many of Bowen's transmitter and receiver components were used, the system would not be airborne so there were no limitations on antenna size.


title: History of radar

text: Primary credit for introducing beamed RDF systems in Britain must be given to Butement. For the CD, he developed a large dipole array, high and wide, giving much narrower beams and higher gain. This could be rotated at a speed up to 1.5 revolutions per minute. For greater directional accuracy, lobe switching on the receiving antennas was adopted. As a part of this development, he formulated the first – at least in Britain – mathematical relationship that would later become well known as the "radar range equation".


title: History of radar

text: By May 1939, the CD RDF could detect aircraft flying as low as and at a range of . With an antenna above sea level, it could determine the range of a 2,000-ton ship at and with an angular accuracy of as little as a quarter of a degree.


title: History of radar

text: Although the Royal Navy maintained close contact with the Air Ministry work at Bawdsey, they chose to establish their own RDF development at the Experimental Department of His Majesty's Signal School (HMSS) in Portsmouth, Hampshire, on the south coast.


title: History of radar

text: HMSS started RDF work in September 1935. Initial efforts, under R. F. Yeo, were in frequencies between 75 MHz (4 m) and 1.2 GHz (25 cm). All of the work was under the utmost secrecy; it could not even be discussed with other scientists and engineers at Portsmouth. A 75 MHz range-only set was eventually developed and designated Type 79X. Basic tests were done using a training ship, but the operation was unsatisfactory.


title: History of radar

text: In August 1937, the RDF development at HMSS changed, with many of their best researchers brought into the activity. John D. S. Rawlinson was made responsible for improving the Type 79X. To increase the efficiency, he decreased the frequency to 43 MHz ( 7 metre wavelength ). Designated Type 79Y, it had separate, stationary transmitting and receiving antennas.


title: History of radar

text: Prototypes of the Type 79Y air-warning system were successfully tested at sea in early 1938. The detection range on aircraft was between 30 and 50 miles (48 and 80 km), depending on height. The systems were then placed into service in August on the cruiser and in October on the battleship HMS "Rodney". These were the first vessels in the Royal Navy with RDF systems.


title: History of radar

text: A radio-based device for remotely indicating the presence of ships was built in Germany by Christian Hülsmeyer in 1904. Often referred to as the first radar system, this did not directly measure the range (distance) to the target, and thus did not meet the criteria to be given this name.


title: History of radar

text: Over the following three decades in Germany, a number of radio-based detection systems were developed but none were true radars. This situation changed before World War II. Developments in three leading industries are described.


title: History of radar

text: In the early 1930s, physicist Rudolf Kühnhold, Scientific Director at the "Kriegsmarine" (German navy) "Nachrichtenmittel-Versuchsanstalt" (NVA—Experimental Institute of Communication Systems) in Kiel, was attempting to improve the acoustical methods of underwater detection of ships. He concluded that the desired accuracy in measuring distance to targets could be attained only by using pulsed electromagnetic waves.


title: History of radar

text: During 1933, Kühnhold first attempted to test this concept with a transmitting and receiving set that operated in the microwave region at 13.5 cm (2.22 GHz). The transmitter used a Barkhausen–Kurz tube (the first microwave generator) that produced only 0.1 watt. Unsuccessful with this, he asked for assistance from Paul-Günther Erbslöh and Hans-Karl Freiherr von Willisen, amateur radio operators who were developing a VHF system for communications. They enthusiastically agreed, and in January 1934, formed a company, "Gesellschaft für Elektroakustische und Mechanische Apparate" (GEMA), for the effort. From the start, the firm was always called simply GEMA.


title: History of radar

text: Work on a "Funkmessgerät für Untersuchung" (radio measuring device for research) began in earnest at GEMA. Hans Hollmann and Theodor Schultes, both affiliated with the prestigious Heinrich Hertz Institute in Berlin, were added as consultants. The first apparatus used a split-anode magnetron purchased from Philips in the Netherlands. This provided about 70 W at 50 cm (600 MHz), but suffered from frequency instability. Hollmann built a regenerative receiver and Schultes developed Yagi antennas for transmitting and receiving. In June 1934, large vessels passing through the Kiel Harbor were detected by Doppler-beat interference at a distance of about . In October, strong reflections were observed from an aircraft that happened to fly through the beam; this opened consideration of targets other than ships.


title: History of radar

text: Kühnhold then shifted the GEMA work to a pulse-modulated system. A new 50 cm (600 MHz) Philips magnetron with better frequency stability was used. It was modulated with 2- μs pulses at a PRF of 2000 Hz. The transmitting antenna was an array of 10 pairs of dipoles with a reflecting mesh. The wide-band regenerative receiver used Acorn tubes from RCA, and the receiving antenna had three pairs of dipoles and incorporated lobe switching. A blocking device (a duplexer), shut the receiver input when the transmitter pulsed. A Braun tube (a CRT) was used for displaying the range.


title: History of radar

text: The equipment was first tested at a NVA site at the Lübecker Bay near Pelzerhaken. During May 1935, it detected returns from woods across the bay at a range of . It had limited success, however, in detecting a research ship, "Welle", only a short distance away. The receiver was then rebuilt, becoming a super-regenerative set with two intermediate-frequency stages. With this improved receiver, the system readily tracked vessels at up to range.


title: History of radar

text: In September 1935, a demonstration was given to the Commander-in-Chief of the "Kriegsmarine". The system performance was excellent; the range was read off the Braun tube with a tolerance of 50 meters (less than 1 percent variance), and the lobe switching allowed a directional accuracy of 0.1 degree. Historically, this marked the first naval vessel equipped with radar. Although this apparatus was not put into production, GEMA was funded to develop similar systems operating around 50 cm (500 MHz). These became the Seetakt for the "Kriegsmarine" and the Freya for the "Luftwaffe" (German Air Force).


title: History of radar

text: Kühnhold remained with the NVA, but also consulted with GEMA. He is considered by many in Germany as the Father of Radar. During 1933–6, Hollmann wrote the first comprehensive treatise on microwaves, "Physik und Technik der ultrakurzen Wellen" (Physics and Technique of Ultrashort Waves), Springer 1938.


title: History of radar

text: In 1933, when Kühnhold at the NVA was first experimenting with microwaves, he had sought information from Telefunken on microwave tubes. (Telefunken was the largest supplier of radio products in Germany) There, Wilhelm Tolmé Runge had told him that no vacuum tubes were available for these frequencies. In fact, Runge was already experimenting with high-frequency transmitters and had Telefunken's tube department working on cm-wavelength devices.


title: History of radar

text: In the summer of 1935, Runge, now Director of Telefunken's Radio Research Laboratory, initiated an internally funded project in radio-based detection. Using Barkhausen-Kurz tubes, a 50 cm (600 MHz) receiver and 0.5-W transmitter were built. With the antennas placed flat on the ground some distance apart, Runge arranged for an aircraft to fly overhead and found that the receiver gave a strong Doppler-beat interference signal.


title: History of radar

text: Runge, now with Hans Hollmann as a consultant, continued in developing a 1.8 m (170 MHz) system using pulse-modulation. Wilhelm Stepp developed a transmit-receive device (a duplexer) for allowing a common antenna. Stepp also code-named the system "Darmstadt" after his home town, starting the practice in Telefunken of giving the systems names of cities. The system, with only a few watts transmitter power, was first tested in February 1936, detecting an aircraft at about distance. This led the "Luftwaffe" to fund the development of a 50 cm (600 MHz) gun-laying system, the "Würzburg".


title: History of radar

text: Since before the First World War, Standard Elektrik Lorenz had been the main supplier of communication equipment for the German military and was the main rival of Telefunken. In late 1935, when Lorenz found that Runge at Telefunken was doing research in radio-based detection equipment, they started a similar activity under Gottfried Müller. A pulse-modulated set called "Einheit für Abfragung" (DFA – Device for Detection) was built. It used a type DS-310 tube (similar to the Acorn) operating at 70 cm (430 MHz) and about 1 kW power, it had identical transmitting and receiving antennas made with rows of half-wavelength dipoles backed by a reflecting screen.


title: History of radar

text: In early 1936, initial experiments gave reflections from large buildings at up to about . The power was doubled by using two tubes, and in mid-1936, the equipment was set up on cliffs near Kiel, and good detections of ships at and aircraft at were attained.


title: History of radar

text: The success of this experimental set was reported to the "Kriegsmarine", but they showed no interest; they were already fully engaged with GEMA for similar equipment. Also, because of extensive agreements between Lorenz and many foreign countries, the naval authorities had reservations concerning the company handling classified work. The DFA was then demonstrated to the "Heer" (German Army), and they contracted with Lorenz for developing "Kurfürst" (Elector), a system for supporting "Flugzeugabwehrkanone" (Flak, anti-aircraft guns).


title: History of radar

text: In the United States, both the Navy and Army needed means of remotely locating enemy ships and aircraft. In 1930, both services initiated the development of radio equipment that could meet this need. There was little coordination of these efforts; thus, they will be described separately.


title: History of radar

text: In the autumn of 1922, Albert H. Taylor and Leo C. Young at the U.S. Naval Aircraft Radio Laboratory were conducting communication experiments when they noticed that a wooden ship in the Potomac River was interfering with their signals. They prepared a memorandum suggesting that this might be used for ship detection in a harbor defense, but their suggestion was not taken up. In 1930, Lawrence A. Hyland working with Taylor and Young, now at the U.S. Naval Research Laboratory (NRL) in Washington, D.C., used a similar arrangement of radio equipment to detect a passing aircraft. This led to a proposal and patent for using this technique for detecting ships and aircraft.


title: History of radar

text: A simple wave-interference apparatus can detect the presence of an object, but it cannot determine its location or velocity. That had to await the invention of pulsed radar, and later, additional encoding techniques to extract this information from a CW signal. When Taylor's group at the NRL were unsuccessful in getting interference radio accepted as a detection means, Young suggested trying pulsing techniques. This would also allow the direct determination of range to the target. In 1924, Hyland and Young had built such a transmitter for Gregory Breit and Merle A. Tuve at the Carnegie Institution of Washington for successfully measuring the height of the ionosphere.


title: History of radar

text: Robert Morris Page was assigned by Taylor to implement Young's suggestion. Page designed a transmitter operating at 60 MHz and pulsed 10 μs in duration and 90 μs between pulses. In December 1934, the apparatus was used to detect a plane at a distance of one mile (1.6 km) flying up and down the Potomac. Although the detection range was small and the indications on the oscilloscope monitor were almost indistinct, it demonstrated the basic concept of a pulsed radar system. Based on this, Page, Taylor, and Young are usually credited with building and demonstrating the world's first true radar.


title: History of radar

text: An important subsequent development by Page was the duplexer, a device that allowed the transmitter and receiver to use the same antenna without overwhelming or destroying the sensitive receiver circuitry. This also solved the problem associated with synchronization of separate transmitter and receiver antennas which is critical to accurate position determination of long-range targets.


title: History of radar

text: The experiments with pulsed radar were continued, primarily in improving the receiver for handling the short pulses. In June 1936, the NRL's first prototype radar system, now operating at 28.6 MHz, was demonstrated to government officials, successfully tracking an aircraft at distances up to . Their radar was based on low frequency signals, at least by today's standards, and thus required large antennas, making it impractical for ship or aircraft mounting.


title: History of radar

text: Antenna size is inversely proportional to the operating frequency; therefore, the operating frequency of the system was increased to 200 MHz, allowing much smaller antennas. The frequency of 200 MHz was the highest possible with existing transmitter tubes and other components. The new system was successfully tested at the NRL in April 1937, That same month, the first sea-borne testing was conducted. The equipment was temporarily installed on the USS "Leary", with a Yagi antenna mounted on a gun barrel for sweeping the field of view.


title: History of radar

text: Based on success of the sea trials, the NRL further improved the system. Page developed the ring oscillator, allowing multiple output tubes and increasing the pulse-power to 15 kW in 5-µs pulses. A 20-by-23 ft (6 x 7 m), stacked-dipole "bedspring" antenna was used. In laboratory test during 1938, the system, now designated XAF, detected planes at ranges up to . It was installed on the battleship USS "New York" for sea trials starting in January 1939, and became the first operational radio detection and ranging set in the U.S. fleet.


title: History of radar

text: In May 1939, a contract was awarded to RCA for production. Designated CXAM, deliveries started in May 1940. The acronym RADAR was coined from "Radio Detection And Ranging". One of the first CXAM systems was placed aboard the USS "California", a battleship that was sunk in the Japanese attack on Pearl Harbor on December 7, 1941.


title: History of radar

text: As the Great Depression started, economic conditions led the U.S. Army Signal Corps to consolidate its widespread laboratory operations to Fort Monmouth, New Jersey. On June 30, 1930, these were designated the Signal Corps Laboratories (SCL) and Lt. Colonel (Dr.) William R. Blair was appointed the SCL Director.


title: History of radar

text: Among other activities, the SCL was made responsible for research in the detection of aircraft by acoustical and infrared radiation means. Blair had performed his doctoral research in the interaction of electromagnet waves with solid materials, and naturally gave attention to this type of detection. Initially, attempts were made to detect infrared radiation, either from the heat of aircraft engines or as reflected from large searchlights with infrared filters, as well as from radio signals generated by the engine ignition.


title: History of radar

text: Some success was made in the infrared detection, but little was accomplished using radio. In 1932, progress at the Naval Research Laboratory (NRL) on radio interference for aircraft detection was passed on to the Army. While it does not appear that any of this information was used by Blair, the SCL did undertake a systematic survey of what was then known throughout the world about the methods of generating, modulating, and detecting radio signals in the microwave region.


title: History of radar

text: The SCL's first definitive efforts in radio-based target detection started in 1934 when the Chief of the Army Signal Corps, after seeing a microwave demonstration by RCA, suggested that radio-echo techniques be investigated. The SCL called this technique radio position-finding (RPF). Based on the previous investigations, the SCL first tried microwaves. During 1934 and 1935, tests of microwave RPF equipment resulted in Doppler-shifted signals being obtained, initially at only a few hundred feet distance and later greater than a mile. These tests involved a bi-static arrangement, with the transmitter at one end of the signal path and the receiver at the other, and the reflecting target passing through or near the path.


title: History of radar

text: Blair was evidently not aware of the success of a pulsed system at the NRL in December 1934. In an internal 1935 note, Blair had commented:


title: History of radar

text: In 1936, W. Delmar Hershberger, SCL's Chief Engineer at that time, started a modest project in pulsed microwave transmission. Lacking success with microwaves, Hershberger visited the NRL (where he had earlier worked) and saw a demonstration of their pulsed set. Back at the SCL, he and Robert H. Noyes built an experimental apparatus using a 75 watt, 110 MHz (2.73 m) transmitter with pulse modulation and a receiver patterned on the one at the NRL. A request for project funding was turned down by the War Department, but $75,000 for support was diverted from a previous appropriation for a communication project.


title: History of radar

text: In October 1936, Paul E. Watson became the SCL Chief Engineer and led the project. A field setup near the coast was made with the transmitter and receiver separated by a mile. On December 14, 1936, the experimental set detected at up to range aircraft flying in and out of New York City.


title: History of radar

text: Work then began on a prototype system. Ralph I. Cole headed receiver work and William S. Marks lead transmitter improvements. Separate receivers and antennas were used for azimuth and elevation detection. Both receiving and the transmitting antennas used large arrays of dipole wires on wooden frames. The system output was intended to aim a searchlight. The first demonstration of the full set was made on the night of May 26, 1937. A bomber was detected and then illuminated by the searchlight. The observers included the Secretary of War, Henry A. Woodring; he was so impressed that the next day orders were given for the full development of the system. Congress gave an appropriation of $250,000.


title: History of radar

text: The frequency was increased to 200 MHz (1.5 m). The transmitter used 16 tubes in a ring oscillator circuit (developed at the NRL), producing about 75 kW peak power. Major James C. Moore was assigned to head the complex electrical and mechanical design of lobe switching antennas. Engineers from Western Electric and Westinghouse were brought in to assist in the overall development. Designated SCR-268, a prototype was successfully demonstrated in late 1938 at Fort Monroe, Virginia. The production of SCR-268 sets was started by Western Electric in 1939, and it entered service in early 1941.


title: History of radar

text: Even before the SCR-268 entered service, it had been greatly improved. In a project led by Major (Dr.) Harold A. Zahl, two new configurations evolved – the SCR-270 (mobile) and the SCR-271 (fixed-site). Operation at 106 MHz (2.83 m) was selected, and a single water-cooled tube provided 8 kW (100 kW pulsed) output power. Westinghouse received a production contract, and started deliveries near the end of 1940.


title: History of radar

text: The Army deployed five of the first SCR-270 sets around the island of Oahu in Hawaii. At 7:02 on the morning of December 7, 1941, one of these radars detected a flight of aircraft at a range of due north. The observation was passed on to an aircraft warning center where it was misidentified as a flight of U.S. bombers known to be approaching from the mainland. The alarm went unheeded, and at 7:48, the Japanese aircraft first struck at Pearl Harbor.


title: History of radar

text: In 1895, Alexander Stepanovich Popov, a physics instructor at the Imperial Russian Navy school in Kronstadt, developed an apparatus using a coherer tube for detecting distant lightning strikes. The next year, he added a spark-gap transmitter and demonstrated the first radio communication set in Russia. During 1897, while testing this in communicating between two ships in the Baltic Sea, he took note of an interference beat caused by the passage of a third vessel. In his report, Popov wrote that this phenomenon might be used for detecting objects, but he did nothing more with this observation.


title: History of radar

text: In a few years following the 1917 Russian Revolution and the establishment the Union of Soviet Socialist Republics (USSR or Soviet Union) in 1924, Germany's "Luftwaffe" had aircraft capable of penetrating deep into Soviet territory. Thus, the detection of aircraft at night or above clouds was of great interest to the Soviet Air Defense Forces (PVO).


title: History of radar

text: The PVO depended on optical devices for locating targets, and had physicist Pavel K. Oshchepkov conducting research in possible improvement of these devices. In June 1933, Oshchepkov changed his research from optics to radio techniques and started the development of a "razvedyvlatl’naya elektromagnitnaya stantsiya" (reconnaissance electromagnetic station). In a short time, Oshchepkov was made responsible for a technical expertise sector of PVO devoted to "radiolokatory" (radio-location) techniques as well as heading a Special Design Bureau (SKB, spetsialnoe konstruktorskoe byuro) in Leningrad.


title: History of radar

text: The "Glavnoe Artilleriyskoe Upravlenie" (GAU, Main Artillery Administration) was considered the "brains" of the Red Army. It not only had competent engineers and physicists on its central staff, but also had a number of scientific research institutes. Thus, the GAU was also assigned the aircraft detection problem, and Lt. Gen. M. M. Lobanov was placed in charge.


title: History of radar

text: After examining existing optical and acoustical equipment, Lobanov also turned to radio-location techniques. For this he approached the "Tsentral’naya Radiolaboratoriya" (TsRL, Central Radio Laboratory) in Leningrad. Here, Yu. K. Korovin was conducting research on VHF communications, and had built a 50 cm (600 MHz), 0.2 W transmitter using a Barkhausen–Kurz tube. For testing the concept, Korovin arranged the transmitting and receiving antennas along the flight path of an aircraft. On January 3, 1934, a Doppler signal was received by reflections from the aircraft at some 600 m range and 100–150 m altitude.


title: History of radar

text: For further research in detection methods, a major conference on this subject was arranged for the PVO by the Russian Academy of Sciences (RAN). The conference was held in Leningrad in mid-January 1934, and chaired by Abram Fedorovich Ioffe, Director of the Leningrad Physical-Technical Institute (LPTI). Ioffe was generally considered the top Russian physicist of his time. All types of detection techniques were discussed, but radio-location received the greatest attention.


title: History of radar

text: To distribute the conference findings to a wider audience, the proceedings were published the following month in a journal. This included all of the then-existing information on radio-location in the USSR, available (in Russian language) to researchers in this field throughout the world.


title: History of radar

text: Recognizing the potential value of radio-location to the military, the GAU made a separate agreement with the Leningrad Electro-Physics Institute (LEPI), for a radio-location system. This technical effort was led by B. K. Shembel. The LEPI had built a transmitter and receiver to study the radio-reflection characteristics of various materials and targets. Shembel readily made this into an experimental bi-static radio-location system called "Bistro" (Rapid).


title: History of radar

text: The "Bistro" transmitter, operating at 4.7 m (64 MHz), produced near 200 W and was frequency-modulated by a 1 kHz tone. A fixed transmitting antenna gave a broad coverage of what was called a "radioekran" (radio screen). A regenerative receiver, located some distance from the transmitter, had a dipole antenna mounted on a hand-driven reciprocating mechanism. An aircraft passing into the screened zone would reflect the radiation, and the receiver would detect the Doppler-interference beat between the transmitted and reflected signals.


title: History of radar

text: "Bistro" was first tested during the summer of 1934. With the receiver up to 11 km away from the transmitter, the set could only detect an aircraft entering a screen at about range and under 1,000 m. With improvements, it was believed to have a potential range of 75 km, and five sets were ordered in October for field trials. "Bistro" is often cited as the USSR's first radar system; however, it was incapable of directly measuring range and thus could not be so classified.


title: History of radar

text: LEPI and TsRL were both made a part of "Nauchno-issledovatelsky institut-9" (NII-9, Scientific Research Institute #9), a new GAU organization opened in Leningrad in 1935. Mikhail A. Bonch-Bruyevich, a renowned radio physicist previously with TsRL and the University of Leningrad, was named the NII-9 Scientific Director.


title: History of radar

text: Research on magnetrons began at Kharkov University in Ukraine during the mid-1920s. Before the end of the decade this had resulted in publications with worldwide distribution, such as the German journal "Annalen der Physik" ("Annals of Physics"). Based on this work, Ioffe recommended that a portion of the LEPI be transferred to the city of Kharkiv, resulting in the Ukrainian Institute of Physics and Technology (LIPT) being formed in 1930. Within the LIPT, the Laboratory of Electromagnetic Oscillations (LEMO), headed by Abram A. Slutskin, continued with magnetron development. Led by Aleksandr S. Usikov, a number of advanced segmented-anode magnetrons evolved. (It is noted that these and other early magnetrons developed in the USSR suffered from frequency instability, a problem in their use in Soviet radar systems.)


title: History of radar

text: In 1936, one of Usikov's magnetrons producing about 7 W at 18 cm (1.7 GHz) was used by Shembel at the NII-9 as a transmitter in a "radioiskatel" (radio-seeker) called "Burya" (Storm). Operating similarly to "Bistro", the range of detection was about 10 km, and provided azimuth and elevation coordinates estimated to within 4 degrees. No attempts were made to make this into a pulsed system, thus, it could not provide range and was not qualified to be classified as a radar. It was, however, the first microwave radio-detection system.


title: History of radar

text: While work by Shembel and Bonch-Bruyevich on continuous-wave systems was taking place at NII-9, Oshehepkov at the SKB and V. V. Tsimbalin of Ioffe's LPTI were pursuing a pulsed system. In 1936, they built a radio-location set operating at 4 m (75 MHz) with a peak-power of about 500 W and a 10-μs pulse duration. Before the end of the year, tests using separated transmitting and receiving sites resulted in an aircraft being detected at 7 km. In April 1937, with the peak-pulse power increased to 1 kW and the antenna separation also increased, test showed a detection range of near 17 km at a height of 1.5 km. Although a pulsed system, it was not capable of directly providing range – the technique of using pulses for determining range had not yet been developed.


title: History of radar

text: In June 1937, all of the work in Leningrad on radio-location suddenly stopped. The infamous Great Purge of dictator Joseph Stalin swept over the military high commands and its supporting scientific community. The PVO chief was executed. Oshchepkov, charged with "high crime", was sentenced to 10 years at a Gulag penal labor camp. NII-9 as an organization was saved, but Shenbel was dismissed and Bonch-Bruyevich was named the new director.


title: History of radar

text: The "Nauchnoissledovatel'skii ispytalel'nyi institut svyazi RKKA" (NIIIS-KA, Scientific Research Institute of Signals of the Red Army), had initially opposed research in radio-location, favoring instead acoustical techniques. However, this portion of the Red Army gained power as a result of the Great Purge, and did an about face, pressing hard for speedy development of radio-location systems. They took over Oshchepkov's laboratory and were made responsible for all existing and future agreements for research and factory production. Writing later about the Purge and subsequent effects, General Lobanov commented that it led to the development being placed under a single organization, and the rapid reorganization of the work.


title: History of radar

text: At Oshchepkov's former laboratory, work with the 4 m (75 MHz) pulsed-transmission system was continued by A. I. Shestako. Through pulsing, the transmitter produced a peak power of 1 kW, the highest level thus far generated. In July 1938, a fixed-position, bi-static experimental system detected an aircraft at about 30 km range at heights of 500 m, and at 95 km range, for high-flying targets at 7.5 km altitude. The system was still incapable of directly determining the range. The project was then taken up by Ioffe's LPTI, resulting in the development of a mobile system designated "Redut" (Redoubt). An arrangement of new transmitter tubes was used, giving near 50 kW peak-power with a 10 μs pulse-duration. Yagi antennas were adopted for both transmitting and receiving.


title: History of radar

text: The "Redut" was first field tested in October 1939, at a site near Sevastopol, a port in Ukraine on the coast of the Black Sea. This testing was in part to show the NKKF (Soviet Navy) the value of early-warning radio-location for protecting strategic ports. With the equipment on a cliff about 160 meters above sea level, a flying boat was detected at ranges up to 150 km. The Yagi antennas were spaced about 1,000 meters; thus, close coordination was required to aim them in synchronization. An improved version of the Redut, the Redut-K, was developed by Aksel Berg in 1940 and placed aboard the light cruiser "Molotov" in April 1941. "Molotov" became the first Soviet warship equipped with radar.


title: History of radar

text: At the NII-9 under Bonch-Bruyevich, scientists developed two types of very advanced microwave generators. In 1938, a linear-beam, velocity-modulated vacuum tube (a klystron) was developed by Nikolay Devyatkov, based on designs from Kharkiv. This device produced about 25 W at 15–18 cm (2.0–1.7 GHz) and was later used in experimental systems. Devyatkov followed this with a simpler, single-resonator device (a reflex klystron). At this same time, D. E. Malyarov and N. F. Alekseyev were building a series of magnetrons, also based on designs from Kharkov; the best of these produced 300 W at 9 cm (3 GHz).


title: History of radar

text: Also at NII-9, D. S. Stogov was placed in charge of the improvements to the "Bistro" system. Redesignated as "Reven" (Rhubarb), it was tested in August 1938, but was only marginally better than the predecessor. With additional minor operational improvements, it was made into a mobile system called "Radio Ulavlivatel Samoletov" (RUS, Radio Catcher of Aircraft), soon designated as "RUS-1". This continuous-wave, bi-static system had a truck-mounted transmitter operating at 4.7 m (64 MHz) and two truck-mounted receivers.


title: History of radar

text: Although the "RUS-1" transmitter was in a cabin on the rear of a truck, the antenna had to be strung between external poles anchored to the ground. A second truck carrying the electrical generator and other equipment was backed against the transmitter truck. Two receivers were used, each in a truck-mounted cabin with a dipole antenna on a rotatable pole extended overhead. In use, the receiver trucks were placed about 40 km apart; thus, with two positions, it would be possible to make a rough estimate of the range by triangulation on a map.


title: History of radar

text: The "RUS-1" system was tested and put into production in 1939, then entered service in 1940, becoming the first deployed radio-location system in the Red Army. About 45 "RUS-1" systems were built at the Svetlana Factory in Leningrad before the end of 1941, and deployed along the western USSR borders and in the Far East. Without direct ranging capability, however, the military found the "RUS-1" to be of little value.


title: History of radar

text: Even before the demise of efforts in Leningrad, the NIIIS-KA had contracted with the UIPT in Kharkov to investigate a pulsed radio-location system for anti-aircraft applications. This led the LEMO, in March 1937, to start an internally funded project with the code name "Zenit" (a popular football team at the time). The transmitter development was led by Usikov, supplier of the magnetron used earlier in the "Burya". For the "Zenit", Usikov used a 60 cm (500 MHz) magnetron pulsed at 10–20 μs duration and providing 3 kW pulsed power, later increased to near 10 kW. Semion Braude led the development of a superheterodyne receiver using a tunable magnetron as the local oscillator. The system had separate transmitting and receiving antennas set about 65 m apart, built with dipoles backed by 3-meter parabolic reflectors.


title: History of radar

text: "Zenit" was first tested in October 1938. In this, a medium-sized bomber was detected at a range of 3 km. The testing was observed by the NIIIS-KA and found to be sufficient for starting a contracted effort. An agreement was made in May 1939, specifying the required performance and calling for the system to be ready for production by 1941. The transmitter was increased in power, the antennas had selsens added to allow them to track, and the receiver sensitivity was improved by using an RCA 955 acorn triode as the local oscillator.


title: History of radar

text: A demonstration of the improved "Zenit" was given in September 1940. In this, it was shown that the range, altitude, and azimuth of an aircraft flying at heights between 4,000 and 7,000 meters could be determined at up to 25 km distance. The time required for these measurements, however, was about 38 seconds, far too long for use by anti-aircraft batteries. Also, with the antennas aimed at a low angle, there was a dead zone of some distance caused by interference from ground-level reflections. While this performance was not satisfactory for immediate gun-laying applications, it was the first full three-coordinate radio-location system in the Soviet Union and showed the way for future systems.


title: History of radar

text: Work at the LEMO continued on "Zenit", particularly in converting it into a single-antenna system designated "Rubin". This effort, however, was disrupted by the invasion of the USSR by Germany in June 1941. In a short while, the development activities at Kharkov were ordered to be evacuated to the Far East. The research efforts in Leningrad were similarly dispersed.


title: History of radar

text: After eight years of effort by highly qualified physicists and engineers, the USSR entered World War II without a fully developed and fielded radar system.


title: History of radar

text: As a seafaring nation, Japan had an early interest in wireless (radio) communications. The first known use of wireless telegraphy in warfare at sea was by the Imperial Japanese Navy, in defeating the Russian Imperial Fleet in 1904 at the Battle of Port Arthur. There was an early interest in equipment for radio direction-finding, for use in both navigation and military surveillance. The Imperial Navy developed an excellent receiver for this purpose in 1921, and soon most of the Japanese warships had this equipment.


title: History of radar

text: In the two decades between the two World Wars, radio technology in Japan made advancements on a par with that in the western nations. There were often impediments, however, in transferring these advancements into the military. For a long time, the Japanese had believed that they had the best fighting capability of any military force in the world. The military leaders, who were then also in control of the government, sincerely felt that the weapons, aircraft, and ships that they had built were fully sufficient and, with these as they were, the Japanese Army and Navy were invincible. In 1936, Japan joined Nazi Germany and Fascist Italy in a Tripartite Pact.


title: History of radar

text: Radio engineering was strong in Japan's higher education institutions, especially the Imperial (government-financed) universities. This included undergraduate and graduate study, as well as academic research in this field. Special relationships were established with foreign universities and institutes, particularly in Germany, with Japanese teachers and researchers often going overseas for advanced study.


title: History of radar

text: The academic research tended toward the improvement of basic technologies, rather than their specific applications. There was considerable research in high-frequency and high-power oscillators, such as the magnetron, but the application of these devices was generally left to industrial and military researchers.


title: History of radar

text: One of Japan's best-known radio researchers in the 1920s–1930s era was Professor Hidetsugu Yagi. After graduate study in Germany, England, and America, Yagi joined Tohoku University, where his research centered on antennas and oscillators for high-frequency communications. A summary of the radio research work at Tohoku University was contained in a 1928 seminal paper by Yagi.


title: History of radar

text: Jointly with Shintaro Uda, one of Yagi's first doctoral students, a radically new antenna emerged. It had a number of parasitic elements (directors and reflectors) and would come to be known as the Yagi-Uda or Yagi antenna. A U.S. patent, issued in May 1932, was assigned to RCA. To this day, this is the most widely used directional antenna worldwide.


title: History of radar

text: The cavity magnetron was also of interest to Yagi. This HF (~10-MHz) device had been invented in 1921 by Albert W. Hull at General Electric, and Yagi was convinced that it could function in the VHF or even the UHF region. In 1927, Kinjiro Okabe, another of Yagi's early doctoral students, developed a split-anode device that ultimately generated oscillations at wavelengths down to about 12 cm (2.5 GHz).