Jetrader - January/February 2012 - 20

aviation history

History of Radar in Aviation
Director, By Bill Bath, Appraiser Fellow-Administrative Director, Bill Bath, l a i ecto ISTAT International ISTAT International Appraisers’ Program A I e In the 1950s, we were frequently told 950s, 5 radar had been invented in Britain. Wrong. been be It was the investigations into the use of e radio waves to detect ships in poor visibiles ity at the beginning of the 20th century e b that lead to Christian Hülsmeyer receiving to ng g a German patent in 1904. Although the p the the radio tube (UK: valve) had not yet been e (UK: valve) UK: UK a developed, the device could detect a ship d, he device up to a range of 3,000 meters. In 1920, 1920, ange nge 3,000 meters. In 1920, ,000 eters. RC Newhouse of U.S. Bell Labs got a ou se u patent for his experiments, which led to r his the radio altimeter. Then in 1928, the UK altimeter. t HM Signal School was awarded a patent Signal School ign igna S for radio loc tion experiments by one of radio loca i locatio its scient ists L.S. Alder. While performscientists, e t ts, ing radio an radio g r ad antenna measurements at an airﬁeld in 1930, the U.S. Naval Research ﬁ d in 1930, 9 Laboratories scientists noticed that metal Laborator es scientists b rato e tori aircraft cro sing the beam affected the airc t crossing rcraft rossi rc transmissions signiﬁcantly. The German transmissions a i is Navy was resea Navy was researching remote radio measura e earching ing tech ogy in 1933 and the Soviets ing technology n echnolo by 1934 ha already a device to detect 1934 had already 4 a aircraft up to a range of 70 kilometers; airc a aircraft p by 1939, 10 countries had rudimentary 1939, 10 countries 939, o operational radars employing different oper ational radars mploying ifferent op erat ional radars employing dif ferent systems of radio wave propagation. The German experiments by Dr. Rudolf Kuhnold in 1924 using a new, powerful radio tube developed by Phillips, was getting good quality returns from a battleship at 7 miles, but more importantly, during the tests an aircraft was detected when it ﬂ ew through the beam. The result was that by July 1938 the German Freya unit was superior to the British sets sup erior p except it could not calculate altitude; for nav al defense it was sufﬁcient to r naval a detect British coal ship convoys sneakdetect etect ec t ing t hrough the English Channel after the through thro fall of France in 1940. Unaware of the fall f al l existence of this unit, the British Admiex is tence xs n ralty wanted to show they owned the ralt y wanted alt w straits and elected to use ships instead s t r aits st rait s d t of t he e xcellent r ail system to the westf the excellent rail he xc lent a nt ern power stat ions. JU87 dive bombers er er n power stations. w at t bomber s bers r decimated the convoys while ﬂock s of decimate decimated the convoy s while ocks of i convoys while cks Messerschmitts diverted the attention of Mess s Me sserschmitts ess sser British ﬁghters. Br it ish t In addition to the Freya, in 1939 GerIn addition d many had Telefunken 50 cm 8 kW Würzny had y ad burg-A units linked to their anti-aircraft burg-A burg-A units rg guns with a detection range of 30 kilon ns wit h t meters; t he parabola dish both sent and mete the ters; received; modiﬁed with a rotating dipole received; modiﬁ ecei d m eiv the over la t overlapping the o e l apping beams gave an accuracy of 0.5 degrees and 100 meters. When a f 0.5 deg 5 egrees RAF bomb was shot down in May 1940 RAF bomber mber while hidden in cloud, Reichsmarschall while hidd hile hidden dden Hermann Göring boasted that no enemy Herm n ö Her ann Göring aircraft wou ever ﬂy over Germany. airc raft ould aircraft would In 1935, Sir Robert Watson-Watt 1935, 3 (1892-1973) (1892-1973) produced his famous mem892-197 ) orandum etting necessary orandum sett ing out the nece ssar y or dum setting out the necessary research to solve the shortcomings of current developments to make Radio Direction Finding as it was then called, the key element in the defense against enemy air and sea attacks. He decided to use the target’s wings as a horizontal aerial and an emitting wavelength of 25 meters, which would avoid commercial radio signals and employ horizontal polarization ith stacked aerials. polarization with stacked aerials. The polarization w it h st acked aerial s. T he rapid progress in Britain’s development of the detection system was the decif s the h sion s ion to use only parts that were reado were re ily ily available; the motto was “the best “ th the was wa s the enemy of good.” At Daventry a t Daventry in in early 1935, using the BBC’s broadBBC ’s BC BC s cast c ca s t as a beam and a Heyford bomber, Heyford bomber, or d o Watson-Watt Wat son-Watt got a clear response on the response on on e n cathode-ray c athode-ray tube. In May 1935, 75-foot th th 1935, 75-foot 35, masts by De December ma s ts had been erected and by December the sc entis ts ere determinin aircraft t h sc ient ists were determining airc raft the scientists were determining aircraft scie i height to Having height to within 1,000 feet. Hav ing got eight a v in the t the attention of the government, money government, money me was was forthcoming for erecting a chain of s erecting chain ting ti g ha a 360-foot 360-foot transmitting masts (choice of 0 ma st s ( hoic o a s (choice c 20-55 2 5 20 -55 MHz) and lower receiving aerireceiving e ei ng als a whose al s whose pulse signals were fed into were f ed e d wooden there WAAFs w d wooden huts at their base; t here WAAFs here e (Women (Wom (W m ( Women Auxiliary Air Force) performed ) perf or med p er f or rfor the the arduous work of deciphering the decipher i g p pherin blips blips on the scopes for size of the incomlips f the incomh inc ing force, ing force, range, altitude and friend from n o d friend f rom ie foe f oe (i foe (intercepting ﬁghters reﬂ ected back eﬂ ected back cted a muc stronger pulse known as IFF). In much n s IFF ). FF) the lter t the ﬁlter room excavated some 40 feet some 4 0 f eet o e under, under under, Bentley Priory (1766) at Stanmore, at St anmo Stanmore, triangulation stations gave triangu tr iangulation from two stations gave the o direction the enemy force and plotdirectio direct on of t he enemy f orce and plot nemy orce lotted on a huge map table using croupier rakes. Details were passed to the operations rooms at Sector, Group, and Fighter Command HQ, all of whom had identical map tables. From the balconies the controllers could see the disposition of their squadrons: available, cockpit readiness or airborne. The Germans never connected the signiﬁcance signiﬁc ance of the tall radar towers and signiﬁc ance of the tall r adar towers and adar ower s the RAF’s ﬁghters waiting for them until

20 The ofﬁcial publication of the International Society of Transport Aircraft Trading
http://www.ISTAT.org
Jetrader - January/February 2012

Table of Contents for the Digital Edition of Jetrader - January/February 2012
