Radome

Radome (pronounced rey-dohm)

A dome-shaped device used as a protective housing for a radar antenna (although the word is loosely used and applied to structures of varied shapes in which radar equipment is installed).

1940–1945: A portmanteau word, a blend of ra(dar) + dome.  In electronics, radar is a device for determining the presence and location of an object by measuring the time for the echo of a radio wave to return from it and the direction from which it returns and in figurative use refers to a means or sense of awareness or perception.  Dating from 1940-1945, radar was originally the acronym RADAR which was creation of US scientific English: RA(dio)D(etecting)A(nd)R(anging).  In the way English does things, the acronym RADAR came to be used with such frequency that it became a legitimate common noun, the all lower-case “radar” now the default form.  Dating from 1505–1515, dome was from the Middle French domme & dome (a town-house; a dome, a cupola) (which persists in modern French as dôme), from the Provençal doma, from the Italian duomo (cathedral), from the Medieval Latin domus (ecclesiae; literally “house (of the church)”), a calque of the Ancient Greek οἶκος τῆς ἐκκλησίας (oîkos tês ekklēsías).  Radome is a noun & verb; the noun plural is radomes.

Spherical radomes at the Pine Gap satellite surveillance base, some 11 miles (18 km) south-west of Alice Springs in Australia's Northern Territory.  Officially, it's jointly operated by the defence departments of the US and Australia and was once known as the Joint Defence Space Research Facility (JDSRF) but, presumably aware nobody was fooled, it was in 1988 renamed the Joint Defence Facility Pine Gap (JDFPG).  The Pine Gap facility is a restricted zone so it's not a tourist attraction which is unfortunate because it's hard to think of any other reason to visit Alice Springs.

Lindsay Lohan on the cover or Radar magazine, June-July 2007.  The last print-edition of Radar was in 2008; since 2009 it's been released on-line.

Radomes don’t actually fulfill any electronic function as such.  They are weatherproof structures which are purely protective (and on ships where space is at a premium they also protect personnel from the moving machinery) and are thus constructed from materials transparent to radio waves.  The original radomes were recognizably domish but they quickly came to be built in whatever shape was most suitable to their location and application: pure spheres, planars and geodesic spheres are common.  When used on aircraft, the structures need to be sufficiently aerodynamic not to compromise performance, thus the early use of nose-cones as radomes and on larger airframes, dish-like devices have been fashioned.

North American Sabre:  F-86A (left) and F-86D with black radome (right).

Introduced in 1947, the North American F-86 Sabre was the US Air Force’s (USAF) first swept-wing fighter and the last trans-sonic platform used as a front-line interceptor.  Although as early as 1950 elements within the USAF were concerned it would soon be obsolete, it proved a solid, versatile platform and close to 10,000 were produced, equipping not on US & other NATO forces but also those of a remarkable number of other nations and some remained in front-line service until the 1990s.  In 1952, the F-86D was introduced which historians of military aviation regard as the definitive version.  As well as the large number of improvements typical of the era, an AN/APG-36 all-weather radar system was enclosed in a radome which resembled an enlarged version of the central bosses previously often used on propellers.

What lies beneath a radome: Heinkel He 219 Uhu with radar antennae array.

The size of the F-86D’s radome is indicative also that the now familiar tendency for electronic components to become smaller is nothing new.  Only a half decade before the F86-D first flew, Germany’s Heinkel He 219 Uhu had entered combat as a night-fighter, its most distinctive feature the array of radar antennae protruding from the nose.  The arrangement was highly effective but, needing to be as large as they were, a radome would have been impossible.  The He 219 was one of the outstanding airframes World War II (1969-1945) and of its type, at least the equal of anything produced by the Allies but it was the victim of the internal politics which bedevilled industrial and military developments in the Third Reich, something which wasn’t fully understood until some years after the end of hostilities.  Remarkably, although its dynamic qualities should have made volume production compelling, fewer than 300 were ever built, mainly because Adolf Hitler (1889-1945; Führer (leader) and German head of government 1933-1945 & head of state 1934-1945): (1) was less inclined to allocate priorities to defensive equipment (attack always his preferred strategy) and (2) the debacle of the earlier Heinkel He 177 Gref heavy bomber (which he described as “the worst junk ever manufactured) had made him distrustful of whatever the company did.

Peak dagmar: 1955 Cadillac Series 62 Coupe de Ville.

As early as 1941, the US car industry had with enthusiasm taken to adorning the front of their vehicles with decorative conical devices they intended to summon in the minds of buyers the imagery of speeding artillery shells, then something often seen in popular publications.  However, in the 1950s, the hardware of the jet-age became the motif of choice but the protuberances remained, some lasting even into the next decade.  They came to be known as “dagmars” because of the vague anatomical similarity to one of the early stars of television but the original inspiration really had been military field ordnance.  Cadillac actually abandoned the use of dagmars in their 1959 models (a rare example of restraint that year) but concurrent with that, they also toured the show circuit with the Cadillac Cyclone (XP-74) concept car.

1959 Cadillac Cyclone (XP-74) concept car.

Although it was powered by the corporation’s standard 390 cubic inch (6.5 litre) V8, there was some adventurous engineering including a rear-mounted automatic transaxle and independent rear suspension (using swing axles, something not as bad as it sounds given the grip of tyres at the time) but few dwelt long on such things, their attention grabbed by features such as the bubble top canopy (silver coated for UV protection) which opened automatically in conjunction with the electrically operated sliding doors.

1958 Edsel Citation Convertible (left) and 1964 GM-X Stiletto, a General Motors (GM) "dream car" built for the 1964 New York World's Fair.

Most innovative however was a feature which wouldn’t reach volume production until well into the twenty-first century: Borrowing from the North American F86-D Sabre, two radomes were fitted at the front, housing antennae for a radar-operated collision avoidance system (ROCAS) which fed to the driver information on object which lay in the vehicle’s path including distance and the length it would take to brake, audible signals and a warning lights part of the package.  Unfortunately, as was often the case with the concept cars, the crash avoidance system didn't function, essentially because the electronics required for it to be useful would not for decades become available.  As the dagmars had, the Cyclone’s twin radomes attracted the inevitable comparisons but given the sensor and antennae technology of the time, two were apparently demanded although, had Cadillac more slavishly followed the F-86D and installed a single central unit, the response might have been even more ribald, the frontal styling of the doomed Edsel then still being derisively compared to female genitalia; cartoonists would have had fun with a Cyclone so equipped seducing an Edsel.  In 1964, there's never been anything to suggest GM's designers were thinking of the anatomical possibilities offered by an Edsel meeting a Stiletto.