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.

Dome

Dome (pronounced dohm)

(1) In architecture, a vault, having a circular plan and usually in the form of a portion of a sphere, so constructed as to exert an equal thrust in all directions.

(2) A domical roof or ceiling; a polygonal vault, ceiling, or roof.

(3) Any covering thought to resemble the hemispherical vault of a building or room; anything shaped like a hemisphere or inverted bowl.

(4) In water management, (usually in dam design), a semidome having its convex surface toward the impounded water.

(5) In crystallography, a form having planes that intersect the vertical axis and are parallel to one of the lateral axes.

(6) In geology, an upwarp (a broad anticline (a fold with strata sloping downwards on each side) caused by local uplift).

(7) In geology, a mountain peak having a rounded summit (a structure in which rock layers slope away in all directions from a central point).

(8) As vistadome, in passenger vehicles (usually railroad cars), a raised, glass-enclosed section of the roof of, placed over an elevated section of seats to afford passengers a full view of scenery (not usually truly in the hemispherical shape of a dome).

(9) In horology, the inner cover for the works of a watch which snaps into the rim of the case.

(10) A building; a house; an edifice (obsolete except as a literary device).

(11) As heat dome, a meteorological phenomenon in which the interplay of high & low pressure atmospheric systems interact to produce static, warm air over a large area.

(12) To cover with or as if with a dome; to shape like a dome.

(13) To rise or swell as a dome.

(14) In slang, a person's head (the form chrome dome used of the bald).

(15) In slang (both military and in some criminal classes), to shoot in the head (often in the form “got domed”).

(16) In African-American slang, to perform fellatio upon.

1505–1515: 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).  Dome is a noun & verb, domed & doming are verbs and domelike, domical, domish & domesque are adjectives; the noun plural is domes.

By the 1650s, the formalized use in architecture ensured the meaning was (more or less) standardized as “a round, vaulted roof, a hemispherical covering of a building” and thus the ultimate specialized evolution from the Greek dōma (a house, housetop (used especially of those with a roof “in the eastern style”), from domos (house), from the primitive Indo-European root dem- (house, household).  The medieval use of the German dom and Italian duomo as verbal shorthand for “cathedral” (essentially a clipping from “house of God”) was picked up in the imperfect way so many words entered English to describe architectural features in the style of hemispherical cupolas, the domes at the intersection of the nave and the transept, or over the sanctuary, characteristic architectural feature of Italian cathedrals.  The sense in English of “a building, a house” had been borrowed in English as early as the 1510s and was used mostly of stately homes and it endures but only as a literary device and it’s rarely seen outside of poetry.

The shape occurs to one degree or another in nature and is common in man-made objects and the built environment so dome is an often seen modifier (cake dome, pleasure dome, lava dome; onion dome et al) and appears in the opening lines of one of the most cherished fragments of English verse: Kubla Khan (1797) by Samuel Taylor Coleridge (1772-1834).

In Xanadu did Kubla Khan
A stately pleasure-dome decree:
Where Alph, the sacred river, ran
Through caverns measureless to man
Down to a sunless sea.

Some of the use has also been opportunistic and not especially domical.  Vistadomes were raised, glass-enclosed sections built into the roofs of railway carriages, placed over an elevated section of seats to afford passengers a better view of the scenery.  The idea was picked up by General Motors, the Oldsmobile Vista Cruiser station wagon (1964-1977), the Buick Roadmaster Estate (1991-1996) and the Scenicruiser busses (1954-1956 and made famous in the Greyhound livery some wore until the 1970s) all used raised, partially-windowed sections although none were officially described as “domes”.

The Hagia Sophia, now the main mosque in Istanbul; the minarets were added after the fall of Constantinople to the Ottoman Turks in 1453 and there are many architectural critics who maintain visually they improve the balance of the structure.  The illustration on the right shows how the Byzantine engineers used pendentives to make the construction of domes possible.     

Domes however are most associated with grand-scale, representational architecture (although quite a few builders of McMansions found them hard to resist).  One intriguing aspect of structural engineering upon which the integrity of a dome depends on what are called pendentives (the triangular segments of the lower part of a hemispherical dome left by the penetration of the dome by two semicircular vaults intersection at right angles).  Dating from 1727, pendentive was from the mid-sixteenth century French pendentif, from the Latin pendentem (nominative pendens) (hanging and the source of the English “pendulous”), the present participle of pendere (to hang) from the primitive Indo-European roots pen & spen- (to draw, stretch, spin).  What pendentives permit is the use of a circular dome over a square void square room or an elliptical one over something rectangular room.  Pendentives, (geometrically the triangular segments of a sphere), taper to points at the bottom and spread at the top to establish the continuous circular or elliptical base as required.  As structural supports, pendentives distribute the bulk of a dome’s weight to the four corners (the strongest points) and ultimately to the piers and the foundations below.  The classic example is the Hagia Sophia, the sixth century Byzantine cathedral at Constantinople (modern day Istanbul).  It was converted into a mosque when Constantinople fell to the Ottoman Turks in 1453 and, after a century-odd as a museum, is again a mosque.

Scale model of Germania.  Hitler would spend hours pondering the details but in 1945, he spent even longer looking at the model of what was planned for the Austrian city of Linz where he'd decided to have his tomb installed.

Domes have long been a favorite of emperors, dictators and those other megalomaniacs: architects.  A truly monumental one would have been the Volkshalle (People's Hall and known also as the Große Halle (Great Hall) & Ruhmeshalle (Hall of Glory), the centerpiece of Adolf Hitler’s (1889-1945; Führer (leader) and German head of government 1933-1945 & head of state 1934-1945) never realized plan to re-built Berlin as Germania, a worthy Welthauptstadt (world capital) of his “thousand year Reich”.  Although Albert Speer (1905–1981; Nazi court architect 1934-1942; Nazi minister of armaments and war production 1942-1945) was Germania’s chief architect, in some aspects he was really a glorified draftsman, correcting the technical errors in the drawings passed to him by the Führer who had be sketching parts of the design since the early 1920s.

Even by the standards of the super-dimensionality which was characteristic of the Third Reich, the domed hall would have been extraordinary.  The oculus would have been 46 m (151 feet) in diameter which would have accommodated the entire rotunda of Hadrian's Pantheon and the dome of St Peter's Basilica.  The  250 m (820 feet) diameter of the dome was (and this was a signature of Speer’s approach), bigger even than Hitler had requested and he was much displeased to learn of a rival architect’s plans for a dome 15 m (49 feet) greater in diameter to sit atop the city’s new railway station.  As things turned out, none of the grandiose structures were ever built and although a tinge of regret can be found in Speer’s post-war thoughts, even he admitted the designs were a failure because of “their lack of human scale”.

Berlin's rebuilt Reichstag with steel & glass dome.

Berlin did however eventually get a new dome, albeit it one rendered not in granite but the glass and steel the Führer thought was fine for factories and warehouses but which would have appalled him as a method of construction for public, representational architecture.  Plonked atop the rebuilt Reichstag, it was said to symbolize the reunification of Germany although quite how it managed that has never really been explained although the distinctive structure has become a city landmark and people seem to like it.  A clever design, it sits directly above the chamber of the Bundestag (the lower house of the bicameral federal parliament) and permits public observation, the clever design also reducing energy use by optimizing the input of natural light while moving shrouds minimize glare and heat-soak.

Cinerama Dome, Los Angeles in 1965, the year of its greatest commercial success.

The Cinerama Dome movie theatre sits on Hollywood’s Sunset Boulevard.  Opened in 1963, the Cinerama Dome introduced a new concept for film projection, a curved screen which sat inside a geodesic dome based on the design developed by US systems theorist & architect Richard Buckminster Fuller (1895–1983), one attraction of which was such things could be built at lower coast and in much less time than a conventional theatre building.  Intended to be the first of perhaps thousands around the planet, it was built in a still remarkable four months but it remains the only concrete geodesic on the planet and while it has operated intermittently since being closed during the COVID-19 pandemic, its future is uncertain and although it will probably be preserved as a historic building, it’s likely to be re-purposed as retail or restaurant space.

Lindsay Lohan at the Scary Movie V premiere, Cinerama Dome, April 2013.

The end of the line for Cinerama is another marker in the evolution of the technology which underpinned the evolution of the US economy from one based on agriculture, to one increasingly industrial to one geared around the military & entertainment.  In the 1950s, cinema’s greatest challenge came from television and the film studios fought back by creating differentiation in their products.  The venture into 3D proved a cul-de-sac for a number of reasons but one thing cinemas could do was make their big screens huge and during the 1950s the wide-screen Cinemascope enjoyed a boom.  However, there was a limit to how much screens could grow, hence the interest in Cinerama which projected onto a curved screen designed to take advantage of the way the human eye sees and processes images, the system at its best when provided by three synchronized projectors.  The idea lives on in the curved screens which have become popular among gaming freaks who enjoy the sense of “envelopment”.  It was also the era during which populations moved further from city centres into suburbs and thus, cinemas also needed to move, more of which (but often smaller) would be required.  Thus the attraction of the geodesic dome came which, largely pre-fabricated, was cheap to produce and quick to assemble.  However, Cinerama was expensive to film, to print, to produce and the sheer size and weight of the prints meant it was costly even to ship the material to venues and the conversion process to something which could be used with conventional projection.

Heat Domes

July 2023 Global heat map from the Climate Change Institute, University of Maine, USA.  For those unconvinced, Fox News continues to provide alternative facts.

The “heat dome” is a weather phenomenon, the physics of which has for decades been understood but of late the term has entered general use as much of the northern hemisphere has suffered from prolonged, unusually high temperatures, July 2023 measured as the hottest month ever recorded.  A heat dome occurs when a large, high-pressure system traps and concentrates hot air in a specific region, leading to prolonged and extremely high temperatures. Under a heat dome, the atmospheric pressure aloft prevents the hot air from rising and dissipating, effectively acting as a lid or cap over the area, thus the image of a dome sitting over the land.

The UK's Royal Meteorological Service's simple illustration of the physics of a heat dome.  Heat domes are also their own feedback loop.  A static areas of high pressure which already contains warm or hot air trapped under the high will become hotter and hotter, creating a heat dome.  Hot air will rise into the atmosphere, but high pressure acts as a lid and causes the air to subside or sink; as the air sinks, it warms by compression, and the heat builds. The ground also warms, losing moisture and making it easier to heat even more.

Superleggera

Superleggera (pronounced soo-per-lee-ghera)

(1) In automotive coach-building, a method of construction which combined a framework of thin steel tubes with aluminum outer panels, producing a lightweight structure.

(2) In recent years, a designation used as a model name to refer to a “lightweight” vehicle even if not a classic superleggera structure.

1935 (a patent for the technique issued in 1936):  From the Italian superleggera (super light) (feminine singular of superleggero), the construct being super- +‎ leggero.  Super was from the Latin super-, from the Proto-Italic super, from the primitive Indo-European upér (over, above) which was cognate with the Ancient Greek ὑπέρ (hupér) (above) and the Proto-Germanic uber (now familiar in English and translated as “over” although this doesn’t wholly convey the sense in Modern German).  Leggero (light in weight, slight, thin) was from the Old French legier, from the Vulgar Latin leviārius, from the Latin levis, from the Proto-Italic leɣis, from the primitive Indo-European hlengwih-, from hléngus, from hleng (lightweight). The cognates included the Sanskrit लघु (laghú), the Ancient Greek ἐλᾰφρός & ἐλᾰχῠ́ς (elaphrós & elakhús) and the Old English lēoht (the ultimate source of the English light).  Superleggera is a noun & adjective; the noun plural is superleggeras (or in the Italian the masculine plural is superleggeri, the feminine plural superleggere).

Carrozzeria Touring and superleggera

It was in 1926 that two Milanese lawyers discussed how bored they were with mundane, if lucrative, legal work and much preferred the exciting world of the automobile, the industry then something like that of IT in the early twenty-first century in that a critical mass of users had been established, growth was consistent and new ventures were coming and going amid a milieu of M&A (mergers & acquisitions).  The lawyers negotiated a controlling interest in Milan-based coachbuilder Carrozzeria Falco, changing the company’s name to Carrozzeria Touring.  Contracts to provide bodywork soon followed including from some of the industry’s major manufacturers including Citroën, Isotta Fraschini & Alfa Romeo and for some time they continued to adopt Falco’s methods which was an adaptation of the “Weymann” system which involved laying fabric over lightweight frames supported by a traditional separate chassis.  Touring produced elegant coachwork of a high quality and attracted the patronage of both Benito Mussolini (1883-1945; Duce (leader) & prime-minister of Italy 1922-1943) and Victor Emmanuel III (1869–1947; King of Italy 1900-1946) although perhaps more influential was the Queen who was often photographed alighting from one of Touring’s large cars, a more imposing sight than the exit of her diminutive husband.

1938 Alfa Romeo 8C-2900B LeMans with Touring Superleggera (left), a wrought-iron artwork installation based on the idea using the Volkswagen Beetle as a model (centre) and Lindsay Lohan with conventional (body-on-chassis) Beetle (Herbie: Fully Loaded (2005)).

Touring proved innovative in its use of strong, lightweight alloys to support the fabric skins and they enjoyed much success also in applying the technique to aircraft components such as wings and fuselages but during the 1930s with both the military and civilian airlines wanting to fly higher, faster, for longer and in all weather, the shift was beginning towards all-metal construction.  This was an organic evolution of the Weymann technique but the weight and other characteristics of sheet aluminum differed greatly from stretched-fabric and the system needed substantially to be re-engineered and it was the lessons learned from fabricating fuselages which led to Touring developing superleggera, the design patented in 1936.  The essence of superleggera was a skeleton of small diameter tubes which formed a body’s core shape, to which were attached thin aluminum-alloy panels which provided both aerodynamic form and strength.  Compared with earlier methods, as well as being inherently light, the method afforded great flexibility in fashioning shape and Touring took advantage of the properties of the metal to create both complex and flowing curves.  Some of their cars of the era did have lovely lines and in addition to the collaboration with Alfa Romeo which yielded sports cars, gran turismo machines and racing cars, the house attracted business from Lancia, Bianchi and others.

1938 Lancia Astura IV series coupé by Touring (left), 1949 Ferrari 166mm barchetta by Touring (centre), and 2014 Ducati 1199 Superleggera (right).

In the post war years, an era in which demand was high and regulations rare, the number of cars built according to the superleggera system increased as Touring licensed the use of its patent to others including Hundon in the US, Pegaso in Spain and Bristol, Aston Martin & Lagonda in England.  Bristol particularly took to the idea because of their long experience with airframes but perhaps the most influential stylistically was the 1948 Ferrari 166 MM Touring barchetta, a charismatic shape which provided a template which would remain recognizable in Ferraris for a quarter-century, the motif of the egg-crate grill still in use today.  While superleggera was unsuited to volume production, for the exclusive ranges at the upper end of the market it was ideal and both Lamborghini and Maseratis emerged built with the technique.  Although the two are sometimes confused because there are visual similarities under the skin, the space-frame method differs in that it can support the whole structural load whereas a superleggera is attached to an existing chassis.

1960 Aston Martin DB4 GT Zagato (left), 1961 Aston Martin DB4 Convertible (centre; the Volante designation wasn't then in use) and 1965 Aston Martin DB5 Saloon.

In the public mind, the most enduring connection was with Aston Martin which was granted a license to use the design and the Superleggera construction method at its Newport Pagnell plant for a fee of £9 for each of the first 500 bodies and £5 for each subsequent unit and the DB4 & DB5 (the latter made famous in the early James Bond films) were both built thus.  However, they represented something of the end of the era because governments were starting to pass laws which demanded road cars attain a certain degree of crash-worthiness, something the superleggera technique couldn’t be adapted conform to without sacrificing the very lightness which was its raison d'etre.  Additionally, the manufacturers were moving swiftly to replace body-on-frame with unit-construction.  Touring attempted to adapt to the changing environment by offering its services as a coach-builder for small, exclusive production runs and made the necessary capital investment but it had become crowded field, the supply of coach-builders exceeding the demand for their skills.  Touring ceased operations in 1966 but four decades on, there was an unexpected revival of the name, the company re-established as Carrozzeria Touring Superleggera, offering automotive design, engineering, coach-building, homologation services, non-automotive industrial design, and the restoration of historic vehicles.  A number of very expensive one-off and limited-production ventures for Maserati, Alfa Romeo and Bentley followed but what attracted most comment was the Sciàdipersia, shown in coupé form at the Geneva Motor Show in 2018, the cabriolet introduced the flowing year.  Based on the underpinnings of the Maserati Grantourismo, although owing no visual debt, it was very much in the tradition of the three Maserati 5000 GTs Touring built in 1959-1960, the first of which had been ordered by the Shah of Iran.  Superleggera however is now just a name with an illustrious history, the method of construction no longer in use and when used as a model designation, it now simply denotes what a literal translation of the Italian suggests: lightweight.

The original Maserati 5000 GT "Shah of Iran" by Touring (left; chassis #103-002) and Touring's Maserati Sciàdipersia in coupé form (centre; 2018) and roadster (right; 2019).

Vickers Wellingtons (B-series, Mark 1) during production, the geodesic structure visible, Brooklands, England, 1939.

There are obvious visual similarities between the classic superleggera method and the geodesic structure used in airframes and some buildings, most famously the “geodesic dome”.  The imperatives of both were strength both aim to create strong and lightweight structures, but they differ in their specific design and application.  As used in airframes, the geodesic structure consisted of a network of intersecting diagonal braces, creating a lattice framework which distributed loads as evenly as possible while providing a high strength-to-weight ratio.  This was of great significance in military airplanes used in combat because it enhanced their ability better to withstand damage better, the stresses distributed across the structure rather than being restricted to a limited area which could create a point-of-failure.  The geodesic framework was based on geometric principles which had been developed over centuries and typically employed hexagons & triangles to render a structure which was both rigid & light.  Superleggera construction differed in that it involves the creation of a lightweight tubular frame, covered with aluminum body panels of a thinness which wouldn’t have been possible with conventional engineering.  The attraction of the superleggera technique was the (relatively) minimalistic framework supported the skin, optimizing weight reduction without compromising strength.  So, structurally, the difference was the geodesic design used a network of intersecting braces to form a lattice, while the superleggera construction used a tubular frame covered with panels.

Geodesic

Geodesic (pronounced jee-uh-des-ik or jee-uh-dee-sik)

(1) In spherical geometry, a segment of a great circle.

(2) In mathematics, a course allowing the parallel-transport of vectors along a course that causes tangent vectors to remain tangent vectors throughout that course (a straight curve, a line that is straight; the shortest line between two points on a specific surface).

1821: A back-formation from geodesy (a branch of science dealing with the measurement and representation of Earth, its gravitational field and geodynamic phenomena (polar motion, Earth tides, and crustal motion) in three-dimensional, time-varying space and with great (and "down-to-earth" as it were) practical application in surveying.  The adjectives geodesical & geodetic had first appeared in 1818 & 1819 respectively, both from geodetical which had been in use since the early seventeenth century.  All the forms are derive ultimately from the Ancient Greek γεωδαισία (geodaisía) from γῆ (geo) (earth) + δαιεῖν (daiesthai) ("to divide" or "to apportion") and the use in English was most influenced by the French géodésique, dating from 1815.  In general use, the word entered general use after 1953 when it was used of the "geodesic dome" (a structure built according to geodesic principles); despite the earlier use in wartime aircraft construction, the use there was only ever "engineer's slang".    Geodesic is a noun & adjective, geodesicity is a noun, geodesical is an adjective and geodesically is an adverb; the noun plural is geodesics.    The alternative adjectival form geodetic appeared in 1834 but fell from use by mid-century.  

Four-dimensional space-time.

Geodesic describes the curve that locally minimizes the distance between two points on any mathematically defined space, such as a curved manifold; essentially the path is the one of the most minimal curvature so, in non-curved three-dimensional space, the geodesic is a straight line.  Under Albert Einstein's (1879-1955) theory of general relativity (1915), the trajectory of a body with negligible mass on which only gravitational forces are acting (ie a free falling body), defines the geodesic in curved, four-dimensional spacetime.  Dictionaries and style guides seem to prefer “space-time” but scientists (and space nerds) like “spacetime” and because it was one of them who “invented it”, it seems polite to ignore the hyphen.  The term, a calque of the German Raumzeit (the construct in English being (obviously) space + time) first appeared in a paper by German mathematician Hermann Minkowski (1864–1909), published in the Philosophical Review.  The existence of the noun plural "spacetimes" does not imply something to do with the so-called multiverse (in cosmology, a hypothetical model in which simultaneously more than one universe exists) but rather that there are different space-times created in different places at different times.

General relativity fan girl Lindsay Lohan in optical illusion dress from the Autumn-Winter collection of interior designer Matthew Williamson (b 1971), illustrating an object causing the curvature of spacetime, Gift Global Gala, Four Seasons hotel, London, November 2014.  An “optical illusion dress” is one which uses a fabric print or other device to create the effect and differs from an “illusion dress” which is made with skin-tone fabrics placed to emulate the wearer’s own flesh.

In Einstein's theory of general relativity, gravity is treated not as a force as had been the historic understanding explained in the writings of Sir Isaac Newton (1642–1727) but rather as a curvature of spacetime caused by the presence of mass and (thus) energy.  The Sun, being a massive object, causes a (relatively) significant curvature in the surrounding spacetime and the Earth, as it moves through this curved spacetime, follows a path (a geodesic) which manifests as what appears to be an “orbit” around the Sun.  It is this curvature of spacetime that is perceived as the “gravitational pull” of the Sun on the Earth, keeping it in a (relatively) stable and predictable orbit.  Einsteinian physics supplanted Newtonian physics as the structural model of the universe and nothing has since been the same. 

Hull of Vickers R.100 Airship.

Sir Barnes Wallis (1887-1979) was an English engineer, best remembered as the inventor of the bouncing bomb used by the Royal Air Force in Operation Chastise (dubbed the "Dambusters" raid) to attack the Ruhr Valley dams during World War II and the big Tallboy (6 tonnes) and Grand Slam (10 tonnes) deep-penetration "earthquake" bombs.  Wallis had been working on the Admiralty’s R.100 airship when he visited the Blackburn aircraft factory and was surprised to find the primitive wood-and-canvas methods of the Great War era still in use, a notable contrast to the elegant and lightweight aluminum structure of airships.  He was soon recruited by Vickers to apply his knowledge to the new generation of fixed-wing aircraft which would use light alloy construction for the internal structure.  His early experience wasn’t encouraging, the first prototype torpedo bomber, which used light alloy wing spars inspired by the girder structure of R.100, breaking up mid-air during a test-flight.  Returning to the drawing board, Wallis designed a revolutionary structural system; instead of using beams supporting an external aerodynamic skin, he made the structural members form the aerodynamic shape itself.

The geodesic structure in an airframe.

The principle was that the members followed geodesic curves in the surface, the shortest distance between two points in the curved surface although he only ever referred to it in passing as geodetic; it wouldn’t be until later the label came generally to be applied to the concept.  As a piece of engineering, it worked superbly well, having the curves form two helices at right angles to one another, the geodetic members became mutually supporting, rendering the overall framework immensely strong as well as comparatively light.  Revolutionary too was the space efficiency; because the geodetic structure was all in the outer part of the airframe meant that the centre was a large empty space, ready to take payload or fuel and the inherent strength was soon proven.  While conducting the usual wing-loading stress tests to determine the breakage point, the test routine was abandoned because the wings couldn’t be broken by the test rig.

Vickers Wellseley.

The benefits inherent in the concept were soon demonstrated.  Vickers’ first geodesic aircraft, the Wellesley, entered service in 1937 and in 1938, three of them, making use of the massive fuel capacity the structure made possible, flew non-stop from Ismailia in Egypt to Darwin in Australia, setting a new world record distance of 7,158 miles (11,265 km), an absolute record which stood until broken in 1946 by a Boeing B-29 Superfortress; it remains to this day the record for a single-engined aircraft with a piston engine, and also for aircraft flying in formation.  While the Wellesleys were under construction, Wallis designed a larger twin-engined geodetic bomber which became the Vickers Wellington, the mainstay of the RAF’s Bomber Command until 1943 when the new generation of four-engined heavy bombers began to be supplied in in the volume needed to form a strategic force.  Despite that, the Wellington was still used in many roles and remained in production until after the end of hostilities.  Over eleven-thousand were built and it was the only British bomber to be in continuous production throughout the war.

Vickers Wellington fuselage internal detail.

The final aircraft of the type, with a more complex geodetic structure was a four-engined heavy bomber called the Windsor but testing established it didn’t offer significantly better performance than the heavies already in service, and the difficulties which would be caused by trying to replicate the servicing and repair infrastructure was thought too onerous so it never entered production.  Post-war, higher speeds and operating altitudes with the consequent need for pressurised cabins rendered the fabric-covered geodetics obsolete.

Aston Martin DB4 GT Zagato (one of 19 in the "Continuation Series", production of which began in 2019) during construction, an aluminium panel being attached to the superleggera frame, Aston Martin Works, Newport Pagnell, Buckinghamshire, England.

There are obvious visual similarities between the classic superleggera method and the geodesic structure used in airframes and some buildings, most famously the “geodesic dome”.  The imperatives of both were strength both aim to create strong and lightweight structures, but they differ in their specific design and application.  As used in airframes, the geodesic structure consisted of a network of intersecting diagonal braces, creating a lattice framework which distributed loads as evenly as possible while providing a high strength-to-weight ratio.  This was of great significance in military airplanes used in combat because it enhanced their ability better to withstand damage better, the stresses distributed across the structure rather than being restricted to a limited area which could create a point-of-failure.  The geodesic framework was based on geometric principles which had been developed over centuries and typically employed hexagons & triangles to render a structure which was both rigid & light.  Superleggera construction differed in that it involves the creation of a lightweight tubular frame, covered with aluminum body panels of a thinness which wouldn’t have been possible with conventional engineering.  The attraction of the superleggera technique was the (relatively) minimalistic framework supported the skin, optimizing weight reduction without compromising strength.  So, structurally, the difference was the geodesic design used a network of intersecting braces to form a lattice, while the superleggera construction used a tubular frame covered with panels.

Velocity

Velocity (pronounced vuh-los-i-tee)

(1) Rapidity of motion or operation; swiftness; a certain measurement of speed.

(2) In mechanics and physics, a measure of the rate of motion of a body expressed as the rate of change of its position in a particular direction with time.  It is measured in metres per second, miles per hour etc.

(3) In casual, non technical use, a synonym for speed.

1540-1550: From the Middle French vélocité, from the Latin velocitatem (nominative vēlōcitās) (swiftness; speed), from vēlōx (genitive velocis) (swift, speedy, rapid, quick) of uncertain origin.  It may be related either to volō (I fly), volāre (to fly) or vehere (carry) from the primitive Indo-European weǵh- (to go, move, transport in a vehicle) although some etymologists prefer a link with the Proto-Italic weksloks from the primitive Indo-European weg-slo-, a suffixed form of the root weg- (to be strong, be lively). Although in casual use, velocity and speed are often used interchangeably, their meanings differ.  Speed is a scalar quantity referring to how fast an object is moving; the rate at which an object covers distance.  Velocity is the rate at which an object changes position in a certain direction. It is calculated by the displacement of space per a unit of time in a certain direction. Velocity deals with direction, while speed does not.  In summary, velocity is speed with a direction, while speed does not have a direction.  Velocity is a noun; the noun plural is velocities.

Great moments in velocity stacks

Velocity stacks (also informally known as trumpets or air horns) are trumpet-shaped devices, sometimes of differing lengths, fitted to the air entry of an engine's induction system, feeding carburetors or fuel injection.  Velocity stacks permit a smooth and even flow of air into the intake tract at high velocities with the air-stream adhering to the pipe walls, a process known as laminar flow.  They allow engineers to modify the dynamic tuning range of the intake tract by functioning as a resonating pipe which can adjust the frequency of pressure pulses based on its length within the tract.  Depending on the length and shape of the stack, the flow can be optimized for the desired power and torque characteristics, thus their popularity in competition where the quest is often for top-end power but the flow can also be tuned instead to produce enhanced low or mid-range performance for specialized use.

1973 McLaren M20C.

The 1968 McLaren M8A was built for the Canadian-American Challenge Cup (the Can-Am) and used a new aluminum version (later sold for street use as the ZL1) of the 427 cubic inch (7.0 litre) big-block Chevrolet V8.  Dry sumped and fuel injected, it was rated at 625 bhp.  A series for unlimited displacement sports cars, the wonderful thing about the Can-Am was the brevity of the rules which essentially were limited to (1) enclosed body work and (2) two seats (one of which was close to a fake).  With engines eventually growing beyond 490 cid (8.0 litres) and reaching close to 800 horsepower, the McLarens dominated the series for five years, their era ended only by the arrival of the turbo-panzers, the turbocharged Porsche 917s which in qualifying trim generated a reputed 1500 horsepower.  The McLarens remained competitive however, the final race of the 1974 series won by a McLaren  M20.    

1970 Ferrari 512S.

Ferrari built 25 512S models in 1969-1970 to comply with the FIA’s homologation rules as a Group 5 sports car to contest the 1970 International Championship for Makes.  It used a five-litre V12 and was later modified to become the 512M which, other than modified road cars, was the last Ferrari built for sports car racing, the factory instead focusing on Formula One.

1965 Coventry Climax FWMW flat-16 prototype.

Coventry Climax developed their FWMW between 1963-1965, intending it for use in Formula One.  A 1.5 litre flat-16, both the Brabham and Lotus teams designed cars for this engine but it was never raced and the engines never proceeded beyond the prototype stage.  Like many of the exotic and elaborate designs to which engineers of the era were attracted, the disadvantages imposed by the sheer bulk and internal friction were never overcome and the promised power increases existed in such a narrow power band it’s usefulness in competition was negligible.  Even on the test-benches it was troublesome, the torsional vibrations of the long crankshaft once destroying an engine undergoing testing.  It was Coventry at its climax; after the débacle of the FWMW, the company withdrew from Formula One, never to return.

1970 Porsche flat-16 prototype.

Porsche developed their flat-16 in the search for the power needed to compete with the big-capacity machines in the Can-Am series.  Unable further to enlarge their flat-12, their solution was to add a third more cylinders.  As an engine, it was a success and delivered the promised power but the additional length of the engine necessitated adding to the wheelbase of the cars and that upset their balance, drivers finding them unstable.  Porsche mothballed the flat-16 and resorted instead to forced-aspiration, the turbocharged flat-12 so effective that ultimately it was banned but not before it was tweaked to deliver a reputed 1500+ horsepower in Can-Am qualifying trim and, in 1975, at the Talladega raceway it was used to set the FIA closed course speed record at 221.160 mph (355.923 km/h); the mark stood for five years.

1966 Ford 289 V8 in GT40 Mk 1.

Not all the Ford GT40s had the photogenic cluster of eight velocity stacks.  When the Ford team arrived at Le Mans in 1966, their Mk II GT40s were fitted with a detuned version of the 427 cubic inch (7.0 litre) big-block FE engines used on the NASCAR circuits and instead of the multiple twin-choke carburetors with the velocity stacks familiar to the Europeans, it was fed by a single four barrel unit under a fairly agricultural looking air intake.  On the GT40s, the velocity stacks looked best on the 289 and 302 cubic inch (4.7 & 4.9 litre) small-block Windsor V8s, the ones built with the four downdraft Weber carburetors thought most charismatic.

1967 BRM H-16.

In typically English fashion, the 1949 BRM V16 is celebrated as a glorious failure.  In grand prix racing, it failed for many reasons but in one aspect, it was a great success: the supercharged 1.5 litre engine generated prodigious, if hard to handle, power.  Not discouraged, when a three litre formula was announced for 1966, BRM again found the lure of sixteen cylinders irresistible though this time, aspiration would be atmospheric.  It actually powered a Lotus to one grand prix victory in Formula One but that was its sole success.  Although nice and short, it was heavy and it was tall, the latter characteristic contributing to a high centre of gravity, exacerbated by the need to elevate the mounting of the block to make space for the exhaust system of the lower eight cylinders.  It was also too heavy and the additional power it produced was never enough to offset the many drawbacks.  Withdrawn from competition after two seasons and replaced by a more conventional V12, the FIA later changed the rules to protect BRM from themselves, banning sixteen cylinder engines.

1969 Ferrari 312P.

Build to comply with Group 6 regulations for prototype sports cars, the Ferrari 312 P was raced by the factory towards the end of the classic era for sports car racing which dated back to the early 1950s.  Fielded first with a three litre V12, it was re-powered with a flat-12 in 1971 and has often been described as the Ferrari Formula One car with bodywork and while a simplification, given the engineering differences between the two, that was the concept.  It appeared on the grid to contest the World Sportscar Championship in 1969, a return from a year of self-imposed exile after one of Enzo Ferrari's many arguments with the FIA.  Needing reliability for distance racing, the Formula One engine was slightly detuned and, as in the open wheeler on which it was based, acted as an integral load-bearing part of the structure.  Unlike Ferrari's earlier sports cars, this time the classic array of Webber carburetors was eschewed, the velocity stacks sitting atop Lucas mechanical fuel-injection.

Albert Einstein, Lindsay Lohan and velocity

Velocity plays is a critical component in Albert Einstein’s (1879-1955) Special (1905) & General (1915) Theories of Relativity.  , profoundly influencing our understanding of space, time, and gravity.  In the Special Theory of Relativity, there is an explanation of the perception of “simultaneity”: events simultaneous in one frame of reference may not be simultaneous in another frame moving at a different velocity.  The critical implication of this wais that time was absolute but depends on the relative motion of observers.  This means a moving clock runs slower than one which is static (relative to the observer).  History’s second most quoted equation (number one said to be “2+2=4” although this is contested) is Einstein’s expression of mass-energy equivalence (E=mc²) which shows that mass and energy are interchangeable.  The significance in that of velocity is that as an object's velocity approaches the speed of light, its relativistic mass increases, requiring more energy to continue accelerating.  From this Einstein deduced the speed of light was the “universal speed limit” because for this eventually to be exceeded would require the input of an infinite amount of energy.  Whether such a state might have been possible in the first fraction of a second during the creation of the current universe remains a matter of speculation but as it now exists, the limit remains orthodox science.

The role of velocity in the General Theory of Relativity remains fundamental but is more complex still.  In addition to the dilation of time sue to relative motion, there is also “Gravitational Time Dilation” (due to relative motion, gravity itself causes time to dilate).  Objects moving in strong gravitational fields experience time more slowly than those existing in weaker fields.  Radically, what Einstein did was explain gravity not as a force (which is how we experience it) but as a curvature of space-time caused by the effects of mass & energy and the motion (and thus the velocity) of objects is is influenced by this curvature.  The best known illustration of the concept is that of “Geodesic Motion”: In curved space-time, a free-falling object moves along a geodesic path (the straightest possible between the points of departure & arrival). The velocity of an object influences its trajectory in curved space-time, and this motion is determined by the curvature created by mass-energy.

Two of Lindsay Lohan’s car most publicized car accidents.  All else being equal (which, as Albert Einstein would have explained, probably can’t happen), if an object is travelling at a higher velocity (in the casual sense of "speed"), the damage will be greater.  In these examples, at the point of impact, the Porsche 911 (997) Carrera S (2012, left) was travelling at a higher velocity than the Mercedes-Benz SL 65 AMG roadster (2005, right).

In classical (pre-Einstein) mechanics, the explanation would have been an object traveling at a higher velocity would have its kinetic energy increase quadratically with velocity (ie double the velocity and the kinetic energy increases by a factor of four.  In relativistic physics, as an object's velocity approaches the speed of light, its relativistic mass increases with velocity and relativistic mass contributes to the object's total energy.  For velocities much less than the speed of light (non-relativistic speeds (a car, even with Lindsay Lohan behind the wheel)), the increase in mass is negligible, and the primary difference is the increase in kinetic energy which follows the classical equation.  However, at velocities approaching the speed of light, both the kinetic energy and the relativistic mass increase significantly.  In a car crash, the main determinate of an impact's severity (and thus the damage suffered) is the kinetic energy:  A car traveling at a higher velocity will have significantly more kinetic energy, so any impact will be more destructive; the kinetic energy is determined by the square of the velocity meaning small a small increase in velocity results in a large increase in energy.  So, on the road, it’s really all about energy because the velocity attainable (relative to what’s going to be hit) means any increase in mass is going to be negligible.  However, were a car to be travelling at close to the speed of light the relativistic mass greatly would be increased, further contributing to the energy of the crash and making things worse still.