Greenhouse

Greenhouse (pronounced green-hous)

(1) A structure usually with a skeletal frame supporting panes of glass, Perspex or other translucent materials in which conditions such as temperature, humidity and irrigation are maintained within a desired range, used for cultivating delicate plants or growing plants out of season.

(2) In UK military slang, the clear material of an aircraft’s cockpit (now rare).

(3) In automotive design, the glass (and Perspex) between the beltline and roofline (also called the "glasshouse").

(4) In surgical medicine, a structure shielding an operating table and designed to protect from the transmission of bacteria.

(5) In climatology, as “greenhouse effect”, a description of the general global consequences of the increasing atmospheric concentrations of “greenhouse gases”, notably carbon dioxide (CO₂), methane (CH₄) et al).

(6) In climatology, a hot state in the global climate.

(7) To place (plants) in a greenhouse and (figuratively), to nurture something in some way to promote growth or development.

1655–1665: From the late Middle English greenhouse (house for growing greens), the reference to the vegetables grown (the produce of various colors but much of the foliage was green during the growing process).  The construct was green + house and the form green-house, while now less common, still runs in parallel.  Green was from the Middle English grene, from the Old English grēne, from the Proto-West Germanic grōnī, from the Proto-Germanic grōniz, from the primitive Indo-European ghreh (to grow).  The related forms include the North Frisian green, the West Frisian grien, the Dutch groen, the Low German grön, green & greun, the German grün, the Danish & Norwegian Nynorsk grøn, the Swedish grön, the Norwegian Bokmål grønn and the Icelandic grænn.  The noun use to refer to the color developed from the earlier references to vegetables and having “grened”.  House was from the Middle English hous & hus, from the Old English hūs (dwelling, shelter, house), from the Proto-West Germanic hūs, from the Proto-Germanic hūsą (and comparable with the Scots hoose, the West Frisian hûs, the Dutch huis, the German Haus, the German Low German Huus, the Danish hus, the Faroese hús, the Icelandic hús, the Norwegian Bokmål hus, the Norwegian Nynorsk hus & Swedish hus).  The Germanic forms may have been from the primitive Indo-European skews & kews-, from skewh & kewh- (to cover, to hide).  The word supplanted the non-native Middle English meson & measoun (house), from the Old French maison (house).  The now rare (and effectively probable extinct) plural housen was from the Middle English husen & housen.  In the Old English the nominative plural was hūs.  Greenhouse is a noun & verb and greenhousing & greenhoused are verbs; the noun plural is greenhouses.

Greenhouse: The Orchid House, Kew Gardens.

As structures used to create artificial, environments, optimized for the cultivation of plants, greenhouse has several synonyms.  The earlier noun conservatory dates from the 1560s in the sense of “a preservative”, a development of the adjectival use (having the quality of preserving), from the Latin conservator (keeper, preserver, defender), an agent noun from conservare.  The meaning “a place for preserving or carefully keeping anything” emerged in the 1610s and when used for the growing of flowers & vegetables, such structures came in the 1650s be called greenhouses.  In English, the formal use in musical education as “a school of music; a place for the performing arts” dates from 1805, from the Italian conservatorio or the French conservatoire (places of public instruction and training in some branch of science or the arts, especially music), from the Medieval Latin conservatorium.  The first places so described were Italian and the word came into use in France after the Revolution (1789); the Italian word was used in English after 1771.  Among gardeners and horticulturalists, by the mid-nineteenth century earthier terms such as “planthouse” and “hothouse” were in use, even in places of serious scientific study such as London’s Kew Gardens (the Royal Botanic Gardens) which, for practical reasons, adopted for various greenhouses pragmatic descriptions such as “Palm House”, “Orchid House” et al.

Lindsay Lohan with a pair of ratchet loppers, pruning cuttings for the potting shed, May 2015.

A twentieth century coining was the “poly house”, an allusion to the use of thick, translucent polythene which in the 1930s, supplied at low cost in rolls by the US petrochemical industry, was instant popular, enabling greenhouses to be built quickly and cheaply.  The related “poly tunnel” & “poly-tube” described the use of the same material to produce even smaller micro-environments with the fabrication of long, “roofs” (semi-circular with the appearance of a tube although without a base) which covered the rows of plants; depending on the crop, such structures could be only a few inches high.  There was also the “potting shed” which was different in that it wasn’t a place with any form of climate control and simply a place a gardener (professional or amateur) could work with their tools, pots etc falling conveniently to hand.  “Potting shed” however has been a “loaded” euphemism and metonym since the publication of DH Lawrence’s (1885–1930) Lady Chatterley's Lover (1928) which wasn’t generally available in the UK until 1961 when R v Penguin Books was decided.  That was a test case of recent legislative amendments in which a jury found the novel satisfied the new provision that the work was “in the interests of science, literature, art or learning, or of other objects of general concern”.  According to some (and they still exist in the Conservative Party), society has since been in decline.  In the novel, more was fertilized in the potting shed than the plants.

August 1912: By the time reports about global warming appeared in the popular press, understandings of the basics of human-induced climate change had been understood for almost a century.

Most reputable sources define the greenhouse effect (on Earth and other heavenly bodies) as something like: “The radiative effect of all infrared absorbing constituents in the atmosphere”.  The operation of the greenhouse effect is not unique to the Earth of the post-industrial revolution but what makes it historically unusual is (1) the rapidity of the increase in atmospheric greenhouse gases (GHGs) and (2) that so much of the increase is due to human activity (mostly the burning of fossil fuels).  In the early nineteenth century, French scientists had published papers describing what would later come to be known as the greenhouse effect, deconstructing the consequences of differing compositions in the Earth’s atmosphere and it was a Swedish meteorologist who first applied the term “greenhouse”, an example of the use of a term the general population would find more accessible than the sometime arcane language of science.  The term “greenhouse seems first to have appeared in print in 1937 but for decades, perception of the phenomenon as a problem was restricted to a handful of specialists and even in the scientific community there were many who viewed it as something benign or even beneficial, there being an awareness a rising temperature would make more of the planet habitable and the increasing volume of CO₂ would encourage plant growth, thus benefiting agriculture.  At the time, climate science was in its infancy, satellites and the big computers needed to model the climate system were decades away and the data on which to develop theories simply didn’t exist.  Additionally, it wasn’t until well into the second half of the century those emissions began radically to increase, the assumptions long that any possible problems probably wouldn’t emerge for centuries.

A chilly looking Greta Thunberg (b 2003), during School Strike for Change, protesting against global warming outside the Swedish Parliament, November 2018.  On 3 January 2024, the world's most famous weather forecaster turned 21.

So “greenhouse effect” never really worked as a term successfully to convey the degree of seriousness the issue deserved.  Accordingly, academics, the activist communities and sympathetic journalists began in the late 1970s to use other words but “global warming” although accurate, really wasn’t much of an improvement because “warm” is a generally “positive” word, used to covey the idea of “kindness, friendliness or affection” and while many people probably thought their climate was already hot enough, more (especially those in the “global north”) would probably have welcomed generally warmer weather.  So that didn’t gain the necessary traction and by the early 1990s, “climate change” began to be used interchangeably with “global warming”, the old “greenhouse effect” by now abandoned.  The scientific rationale for this was that in the narrow technical sense, global warming describes only increased surface warming, while climate change describes the totality of changes to Earth's climate system.  However, until well into the twenty-first century, for most of the population in the First World, what in retrospect have come to be understood as manifestations of climate change, things were hardly obvious.  By the 2020s, the linguistic implications in messaging seemed finally understood and “climate crisis”, “climate emergency” and “climate catastrophe” became the preferred terms and while the “climate change deniers” seem now less numerous (at least some perhaps having perished from heat stroke or drowned in one of the “once in 500 year floods” which seem now frequent).  In the political discourse, "climate crisis" and "global heating" seem now the popular forms. 

The Automotive Greenhouse

1970 Series 2 Fiat 124 Coupé (left) and 2022 Chevrolet Camaro ZL1 1LE (right).

The Fiat and Chevrolet represent two approaches to the coupé greenhouse (styled also as the "glasshouse") and both attracted some comment from critics, the Fiat because it was judged around an inch (25 mm) too high to achieve aesthetic success and the Chevrolet because it was too low (the estimates of by how much varied).  The Italian car however was much admired and enjoyed strong demand for most of its life (1967-1975 and given what followed the end of production was probably premature), and at least some of the success was attributable to the comfortable cabin with its generous headspace and the greenhouse which provided outstanding visibility in all directions, am important aspect of what was coming to be understood as “passive safety” (as opposed to “active safety” elements such as seat-belts or crumple-zones).  The low roof-line on the Chevrolet was thought by some to give the car a “cartoonish” quality although it’s a subjective judgment whether that detracted from the look and certainly it lent the thing a low-slung, sporty appearance which was after all presumably what most appealed to the target market.  The practical drawback was the abbreviated greenhouse meant a dark cabin and some compromise in the ease of ingress & egress although descriptions suggesting the space was “claustrophobic” or “oppressive” seem hyperbolic.  As a retro take on the original Camaro (1967-1969), the fifth (2010-2015) & sixth (2016-2024) generation models were well executed although greenhouse and other details unsettled some.  Ms Thunberg approves of neither although, depending on how one deconstructs the numbers, it's debatable which contributes more to the climate crisis.

Standard and Spezial coachwork on the Mercedes-Benz 300d (W189, 1957-1962).  The "standard" four-door hardtop was available throughout the run while the four-door Cabriolet D was offered (off and on) between 1958-1962 and the Spezials (landaulets, high-roofs et al), most of which were for state or diplomatic use, were made on a separate assembly line in 1960-1961.  The standard greenhouse cars are to the left, those with the high roof-line to the right.

The 300d (W189, 1957-1962) was a revised version of the W186 (300, 300b & 300c; 1951-1957) which came to be referred to as the "Adenauer" because several were used as state cars by Konrad Adenauer (1876–1967; chancellor of the FRG (West Germany) 1949-1963).  Although the coachwork never exactly embraced the lines of mid-century modernism, the integration of the lines of the 1950s with the pre-war motifs appealed to the target market (commerce, diplomacy and the old & rich) and on the platform the factory built various Spezials including long wheelbase "pullmans", landaulets, high-roof limousines and four-door cabriolets (Cabriolet D in the Daimler-Benz system).  The high roofline appeared sometimes on both the closed & open cars and even then, years before the assassination of John Kennedy (JFK, 1917–1963; US president 1961-1963), the greenhouse sometimes featured “bullet-proof” glass.  As well as Chancellor Adenauer, the 300d is remembered also as the Popemobile (although not then labelled as such) of John XXIII (1881-1963; pope 1958-1963).

Two from the Daimler-Benz Spezial line: The 1965 Papal Mercedes-Benz 600 (W100) Landaulet (left) built for Pope Paul VI (1897-1978; pope 1963-1978) (left) and the one-off short wheelbase (SWB) 600 Landaulet (right) built for racing driver Graf von Berckheim (Count Graf Philipp-Constantin Eduard Siegmund Clemens Tassilo Tobias von Berckheim, 1924-1984).

The Papal 600 used the higher roof-line which was a feature of some of the Spezial Pullmans & Pullman Landaulets.  The attractions of the high-roof coachwork was (1) greater headroom which afforded more convenient ingress & egress (a practical matter given the cars were sometime parade vehicles used by royalty and military dictators, both classes given to wearing crowns or big hats) and (2) the extended greenhouse made it easier for crowds to see the occupants.  Count von Berckheim's car used the standard roof-line and was the only SWB Landaulet, the other 59 all built on the LWB Pullman platform.

Tumblehome

Tumblehome (pronounced tuhm-buhl-hohm)

(1) In naval architecture, an inward and upward slope of the middle body of a vessel; of the sides of a ship: To incline or slope inwards, to contract above the point of extreme breadth.

(2) A conceptually similar shape applied, in reverse, to the upper body of an automobile.

1828: A compound word, tumble + home.  Tumble was from the Middle English tumblen (to fall over and over again, tumble), frequentative of the Middle English tumben (to fall, leap, dance), from the Old English tumbian, from the Proto-Germanic tūmōną (to turn, rotate).  It was cognate with the Middle Dutch tumelen and the Middle Low German tumelen & tummelen.  Home was from the Middle English home, hom, hoom & ham, from the Old English hām (village, hamlet, manor, estate, home, dwelling, house, region, country), from the Proto-West Germanic haim, from the Proto-Germanic haimaz (home, village), from the Proto-Indo-European tḱóymos (village, home), from the root tḱey-.  The (rare and probably extinct) alternative spelling is tumble home.  Tumblehome is a noun; the noun plural is tumblehomes.

The meaning of the word tumblehome has been well understood from its first appearance in the early nineteenth century but the origin has never been obvious.  Shipbuilders had for centuries been using variations of the design for a number of reasons but the first known instance of the word dates only from 1828 and then without explanation, suggesting the term may already have been in common use, at least within the industry.  An 1848 reference from a shipwright does however hint at some sense of novelty, noting “… the upper works usually incline towards the middle line, or as it is termed “tumble home”.  The word “tumble” to refer to the sides of ships appears to have been used at least as early as 1687 but the compound tumblehome seems not to have emerged for another hundred and fifty-odd years.  The idea always summoned was of the imagery of the sides of a ship “tumbling down” the slope created but why “home” was added remains a mystery, the assumption being it was based either on (1) an association with certain domestic architectural styles of the time (2) the romantic notion of the sea, to which the tumblehome falls, being "home" for sailors or  (3) the idea of a dilapidated house in the throes of "tumbling down", fallen bits an pieces accumulating at the bottom.

Big ships and fast cars

In automotive design (upper), the term is applied when the width of the cabin (cockpit or glasshouse) reduces as the height rises.  Although curved glass in the side windows of cars began widely to be adopted in the mid-1960s, thus creating a mild tumblehome effect, the term is applied only when it is sufficiently severe to be apparent to casual viewers.

In naval architecture (lower), the geometry is reversed, a tumblehome define as a hull which flares out as the sides approach the waterline.  Although in some vessels, the effect is barely detectable by the naked eye, it’s a technical term and applies to all hulls which dimensionally qualify.  The opposite, the classic shape for ships’ hull, is called the flare.

USS Brooklyn, 1896.

Tumblehome, unless taken to extremes, was functional in that it improved stability in warships under sail; sailing ships heel (they tend to lean over when moving) and tumblehome reduced this.  At the time, the biggest contributor to a warship’s mass on the upper decks was the guns and a tumblehome design, moving the centre of gravity lower, allowed armament to be maintained or even increased without further loss of stability.  Additionally, there was the benefit of making it harder for boarding parties to climb aboard.  In commercial shipping, vessels were long taxed on the basis of the square footage of a ship’s deck and fat ships with a pronounced tumble carrying the same freight but taxed less, were attractive.  Government fiscal policy thus influenced and distorted design and engineering principles in the same way tax arrangements of windows affected architecture and those on cylinder bores (adversely) affected engine design.

Lamborghini LP500 Countach prototype, 1971.

The Countach had one of the most extreme implementations, the angle meaning it was possible for only part of the side-window to be lowered but at least the Italians were more thoughtful than the Germans; in 1954, facing a similar challenge with the side-glass on the 300 SL (W198 1954-1957) gullwing, Mercedes-Benz simply fixed the panes, ventilation provided only by small quarterlights.  Neither flow-through ventilation or air-conditioning was available so driving in a gullwing could be hot and sticky experience and there's a reason they're sometimes seen being driven (at low speeds and not on public roads) with at least one door open. .  The tumblehome is used by high-performance cars because of the aerodynamic advantages it confers, reducing frontal area an allowing the curve of the greenhouse to be optimized for air-flow, lowering resistance.  Because of great advances made during the late twentieth century, refinements to tumblehomes no longer deliver the 3-5% improvements in a drag coefficient (CD) which once was possible, engineers now pursuing factional gains.  The origins in cars however lay in the quest for more interior space and for mass-market vehicles, bulging out the sides gained the odd vital inch and the technique, combined with curved side glass, has become almost universal although there has been the odd deviation.  Stylists are predicting tumblehomes are likely to become more exaggerated as sides need to be bulkier to meet more rigorous side-impact regulations and roof-lines are lowered slightly in the quest to reduce drag.

Lindsay Lohan in tumblehome blonde wig.

What professional hair stylists call “the tumblehome” is a triangulated shaping which is most cases can’t be achieved without an expert application of product and when sported by models on photo-shoots, it’s common for the angles and an illusion of volume to be achieved with engineering no more complex than a sheet of cardboard (cut to suit) being attached with hairclips to the back of the head.  The look can however be achieved with synthetics which can be persuaded sustainably to behave in a way human hair naturally resists and Lady Gaga (b 1986) made a tumblehome wig a signature feature of her “Fame Monster” period (2009-2010).  With natural hair, a tumblehome with hair a little shorter than that of Lady Gaga’s wig is sometimes technically achievable given the right hair and a generous use of product the sideways projection would be noticeably less.

Lady gaga in Fame Monster mode.

The tumblehome style with the exaggerated elongations al la Gaga is rarely seen and usually represents a lot of work.  However, many take about as much effort to avoid the similar geometry of the “pyramid head”: a triangular shape with a flat crown area which flares to a wide bushy shape at the ends.  A function of length and weight for those with curly hair, pyramids happen usually when the strands are of almost uniform length and the curls tend to “stack”, the weight meaning the roots sit flattest on the scalp while towards the ends where the effective volume (hair + space) is greatest, the curled strands move sideways, unlike the behavior of straight hair which is purely downwards.

Lindsay Lohan with pyramid head, Saturday Night Live, 2004.

Stylists recommend layers as the best tactic to minimize the triangulation, the strategy essentially to create longer, diagonal layers to frame the face, meaning the remaining curls “sit into each other”.  What this does is simply physics, the layering on the surface reducing the weight, increasing the percentage of the volume on the crown area and although some are resistant, the best results will probably be achieved if the hair is cut dry because it will be presented at its natural weight.  When wet, the moisture content will disguise the extent of the left-right movement and exaggerate the up-down.  The shorter the layers of course the more effective the amelioration but this can be too radical for some so clients need to be turned into realists.

Wankel

Wankel (pronounced wahng-kuh)

A type of rotary internal combustion engine, first produced 1961, named after its inventor, German engineer, Felix (aka Fritz) Wankel (1902-1988).

The Wankel engine is a type of internal combustion rotary engine, one of many based on the a rotary principle, the Wankel using an eccentric drive to convert pressure into rotating motion.  The design was conceived by German engineer Felix Wankel, an eccentric, though clearly gifted, self-taught engineer who was an early convert to National-Socialism (linked with a right-wing political movement in 1921) who joined the NSDAP (the National Socialist German Workers Party which would become the Nazi Party) the following year.  It’s important not to make too much of that, the party in its early days an aggregation of factions which were, literally more nationalist and socialist in character than anything like the racist and ultimately genocidal thing into which the Nazis evolved under Adolf Hitler (1889-1945; Führer (leader) and German head of government 1933-1945 & head of state 1934-1945). 

But an enthusiastic Nazi Wankel certainly was although that didn’t protect him from falling victim to the internecine squabbles which would beset the party to the very end, expelled from the party in 1932 after feuding with his Gauleiter (the regional party boss) who, after Hitler came to power in 1933, succeeded in having Wankel jailed although, under less unpleasant conditions that those tossed into concentration camps.  Indeed, while in prison, he was able to continue working on his rotary engine, a patent for which had been granted to him in 1929.

Felix Wankel admires a shaft.

Wankel though had friends in the party, one of whom approached the Führer, stressing the importance of the amateur engineer’s contribution to German industry and that proved enough to secure his release.  He worked on a variety of projects during the 1930s, some on contract for BMW but mostly for the military including on seals, something which years later would absorb much of his energy at that of many others.  Despite his efforts for the Reich, his attempts to rejoin the party were rebuffed but his friends did gain him the honorary rank of Obersturmbannführer (Lieutenant Colonel) in the Schutzstaffel (The SS (Security Squad or Section), originally Hitler's personal security detail which evolved into a vast party security apparatus and later a parallel army almost a million strong) although his career in the "black mist" wasn't long, Wankel expelled within two years.  The records were lost in the confusion of war so the reasons aren’t known but while it’s tempting to wonder just how ghastly one has to be to be thought too evil for the SS, given the lack of any subsequent punitive action against him, it’s likely he just lost out in another of the squabbles that were so common in the Nazi system, the structures of which actually encouraged internal conflict.

It didn’t stop the Nazi state funding his research including what he was then calling his “rotary motion engine” although progress was slow and slow for a reason, the fundamental flaw in the design not resolved until the 1950s when another engineer, less visionary but more practical, rectified the fault.  Wankel's rotating cul-de-sac was far from unique in wartime Germany, the interest of the regime in technical innovation and the gullibility of party officials drew cranks, con-men and inventors inspired and otherwise.  Among the projects which received interest and sometimes cash from the state was a “non-combustible” material called durofol (which would catch fire), a scheme to create liquid fuel from the roots of fir trees (which consumed three times as much energy as it produced), the production of alcohol from bakery fumes (apparently that one was quickly rejected), a “death ray” championed by notorious drunkard Reichsleiter Robert Ley (1890–1945; head of the German Labour Front 1933-1945), which turned out to be impossible to build or even test, a plan to turn the atmosphere into a conductive element using ionization (which at least has a theoretical basis even if impossible) and the mysterious “Gerloff miracle pistol”, the records for which were lost.  Compared to some of these, Wankel’s engine (which didn’t work) probably appeared quite promising.

Gleitkufenboot (skid boat).

Wankel had other projects too, one of which he would, like his engine, later revisit.  This was the Zischboot (Hiss boat), intended as a small, high-speed torpedo-boat for the navy, a kind of hydrofoil that used clusters of skis.  In the 1970s, Wankel would display a prototype (now called the Gleitkufenboot (skid boat)), powered by an impressively powerful Mercedes-Benz four rotor Wankel engine.  Wankel claimed not only was it impossible to capsize the boat but that it was unsinkable, a notable feature said to be borrowed from certain sea creatures, air-intake "nostrils" with flaps controlled by sensors to ensure no water could penetrate when driving through waves.

Wankel survived the war and suffered not greatly in the denazification process the allied occupation authorities ran to weed out the worst of the worst, his work as an engineer suggesting someone unpolitical and being expelled both from the party and the SS probably helpful in mitigation.  In that he was lucky; had the investigators dug deeper they would have discovered Nazi-era Wankel held some fairly unsavory views and had expressed them more than once.  In the new Germany, those opinions he either no longer held or kept to himself, in 1951 obtaining a position with NSU as a technical consultant.  NSU were interested in his rotary motion engine.      

1957 NSU Prinz.

NSU (the name an abbreviation of "Neckarsulm", the city in which the factory was located) began in 1873 as a knitting machine manufacturer which in 1886 branched out into the production of bicycles and so successful did this prove that by 1892, the knitting machines were abandoned, the factory converted wholly to the building of bicycles.  The first NSU motorcycles appeared in 1901 and were both popular and profitable, encouraging the company in 1905 to enter the potentially even more lucrative market for cars.  Between then and the end of World War II (1939-1945), there were ups and downs but NSU survived and, in December 1946, resumed building bicycles and motorcycles, commercial vehicle production starting in 1949.  These efforts proved successful and the company, by now a significant beneficiary of Wirtschaftswunder (the post-war German "economic miracle"), was by the mid-1950s the world’s largest maker of motorcycles and profitable enough for car production to resume in 1957.     

1958 NSU Prinz Sport.

The car was modest enough, tiny and powered by a 600 cm³ (37 cubic inch) air-cooled twin cylinder powerplant which was essentially two motorcycle engines joined by a common crankcase.  As was fashionable in small European cars of the era, the engine was at the rear, something which would prove a cul-de-sac, most manufacturers outside the Warsaw Pact soon convinced to abandon the idea.  That disenchantment actually extended to Porsche which had the 911’s replacement in production by the mid-1970s, only to find out just about every soul left on the planet who still thought rear-engined cars a fine idea were Porsche 911 buyers who insisted nothing else would do.  The customer being always right, the 911 survives to this day and that a rear-engined machine can be as well-behaved as 911s now are will be no surprise to those familiar with modern electronics but Porsche, remarkably, had engineered a high degree of predictability into its behavior even before computers were robust and fast enough to do the job.  In 1958, NSU didn’t face the same issues of high-speed handling, the new Prinz (Prince) having but 20 bhp (15 kW).  It was wholly utilitarian but suited to the times and sold well, national success (and growing incomes) meaning within a year, the idea of a more profitable up-market version became attractive.  Although little more than an Italian-styled body atop the existing underpinnings and never a huge seller, the Prinz Sport remained in production for a decade and its lightweight and slippery shape made possible an impressive top speed of 75 mph (120 km/h).  By 1968 over twenty-thousand had been built and it was the Prinz Sport NSU used as the basis for the world’s first Wankel-engined car.

The rotary engine, light, powerful and with few moving parts had interested NSU which saw the potential for motorcycles but they also quickly identified the fundamental flaw in the design which Wankel had never resolved: both rotor and rotor housing rotated, each on different axes, creating an assembly almost impossible to keep in balance as well as necessitating an additional housing.  While Wankel proceeded along his path, publicized by NSU in 1954, another NSU engineer, Hanns Dieter Paschke (1920-1999), unbeknown to Wankel, was developing his own version (KKM 57), displayed in 1957 as the DKM 54 at the NSU Research & Development Department in Versuchsabteilung.  Before long, the concept would be refined in that the single housing became static and only the rotor rotated, Wankel’s original vision intriguing but perhaps, even now, impossible to build as a practical working device and NSU devoted some years to making their version exactly that.  In 1964, it was released to the public.

1967 NSU Spider.

In 1964, the Western world was not so laden with rules and restrictions (for good and bad) and it was possible to sell for use on the public highways what were essentially prototypes in development and that the NSU Spider certainly was.  It was also a seen by NSU as an advertisement on wheels, a showcase not only for their upcoming models but also to encourage other manufacturers to buy licenses to produce their own Wankels, an option that would be exercised by many, including Alfa Romeo, Curtiss-Wright, General Motors, Daimler-Benz, Rolls-Royce and Mazda.  For whatever reason, BMW, Felix Wankel's Nazi-era employer, declined.  Citroën, an outfit with a reputation for the quirky, were enthusiastic enough to set up with NSU a Swiss co-venture to pursue the technology.  More than most, the French would come to rue the day they ever heard Wankel’s name.

Skoda (rear) engine bays, the conventional (piston) engine (left) vs the single-rotor Wankel (right).

Although the project never progressed beyond the prototype stage, the Czech manufacturer Skoda was apparently the first to have running vehicles with a rotary engine installed (a complete engine said to have been running as early as 1961) but in 1964, the NSU Spider was the first to go on sale.  It used a single-rotor, water-cooled engine and was easily distinguishable from the Prinz Sport because it was a soft top cabriolet, apart from which it was substantially the same car with only detail differences in styling and specification except it was offered only in red or white.  One other change was definitely apparent however, power had jumped to a heady 50 bhp (37 kW) at a surprisingly low 5,500 rpm, enough to propel the Spider to close to 100 mph (160 km/h) for anyone on the autobahn prepared to push the little machine to the limit.  Never expected to be a big seller, fewer than 2500 were built between 1964-1967, its purpose more to whet the public appetite for what NSU intended to be their entry into the burgeoning middle-class mass market.  Additionally, though not at the time discussed, the Spider’s engine, while at a stage of development beyond being a prototype, was not ready for release to a public using it in a wide variety of ways in different climates in different countries.  The Spider’s customers unwittingly were also NSU’s development test team, something which later in the century would become a handy business model for many software companies.

Given the specifications of the Wankel NSU would produce in the future, it may that the Spider’s single rotor powerplant wasn’t an ideal a test bed for the customers to debug but problems in design and the choice of materials were identified and, where possible, within the limits of metallurgy and the realities of economics the lessons learned were applied.  Nor was the Spider’s specification static, the experiences of the customers applied to improve not only longevity but also power, the later cars enjoying a slight increase in capacity, output now 54 bhp (40 kW) at 6,000 rpm, 4 bhp perhaps not impressing all but it was close to 10% more and although the factory didn’t claim any increase in attainable speed, the most recent Spider owners presumably got there a little more quickly.

1967 NSU Ro 80 (1967-1977).

If the spider had generated interest, the NSU Ro 80, released in 1967, was a sensation.  Even without the novelty of the rotary engine (without which all concede it would doubtless have been a success), it would have made quite an impact.  The body, which does not look out of place even in the twenty-first century, was a modernist masterpiece, trendsetting in a way the 1955 Citroën DS (often called the déesse (literally "goddess")) was just too extreme to be yet more aerodynamically efficient, the Ro 80’s drag coefficient (CD) of .354 just a fraction better than the French car’s .359.  Beneath the skin, the futurist vision continued, the efficient front-wheel-drive packaging in the vanguard of adoption by larger vehicles, four wheel disk brakes (inboard at the front), a semi-automatic transmission, power-assisted rack and pinion steering and all independent suspension.  Reviews upon release were sometimes ecstatic, the only criticism from some who found the interior austere but it was era in which only the most expensive German cars were fitted-out with much beyond the starkly functional; NSU’s designers looked to Le Corbusier and Gropius, not the Jaguar Mark X.

The Ro 80 won the 1968 European Car of the Year award and buyers seemed as impressed as the many journalists who voted NSU.  Out on the autobahns, the twin-rotor engine was a smooth, quiet and a delight to use, the slippery shape meaning the 113 bhp (85 KW) it generated from a comparatively small 995 cm³ (61 cubic inch) displacement allowed it to match the speed of cars with even three times the capacity, the turbine-like feel encouraging a disregard for the 6500 rpm redline which it seemed to exceed without complaint.  The honeymoon didn’t last.  Critics began to notice it was good to match larger six cylinder cars in performance but it came at the cost of a thirst many V8 owners didn’t suffer.  Nor was the Ro 80, so at home cruising at 100 mph (160 km/h) on the autobahn, quite as happy in the stop-start urban conditions where the modern German motorist was now spending much time, some finding the previously admired semi-automatic transmission clumsy to use, the experience jerky.  The Wankel engine didn't deliver much much low-speed torque and drivers had to adjust their technique; those used to the more effortless performance of the 2-3 litre engines most often found in this class of car found negotiating their commute through a succession of red traffic-lights harder work than before.    

Nothing is perfect and such was the appreciation of the Ro 80’s virtues these drawbacks may have been overlooked or at least endured but what couldn’t be forgiven was that the Wankel engines were frequently, numerously, rapidly and expensively failing and, being within the warranty period, it was NSU which bore the cost to repair or replace.  That was bad enough but the car was quickly gaining a reputation for unreliability and sales were falling, exacerbating the financial strain NSU was suffering from all the warranty claims.  Nor was the once profitable motorcycle business there to subsidise the four-wheel venture, production having ended in 1968 to allow the company to focus on the Ro 80.  The problems hadn’t been wholly unexpected, just underestimated; NSU’s engineers had warned the board the engine wasn’t yet ready for production and needed at least months more durability testing and development but, perhaps remembering the relatively smooth introduction of the Spider, and certainly seeking cash-flow, approval was given for a debut in 1967.

It wasn’t difficult to work out where the problems lay which was mostly in the high wear of the apex seals and consequent damage to the rotor housing.  Essentially, the seal failure destroyed the engine, necessitating a replacement and it was not uncommon for replacement engines also to fail and require replacement, again under warranty.  For a small company with limited resources, it was unsustainable and NSU was soon unviable, the takeover by Volkswagen in 1969 said to be a "merger with Audi" only an attempt to glue a veneer of corporate respectability on what was the takeover of a distressed competitor.  It was unfortunate.  In just about every way except the flawed engine, the Ro 80 was years ahead of its time and deserved to succeed.

1967 Mazda Cosmo.

The issue was the engine at that stage of its development given the metallurgy of the time rather than NSU because Mazda, which had in 1961 purchased a licence to produce the Wankel, were suffering the same problems in the Cosmo sports car, introduced also in 1967.  The Cosmo however, was a low-volume model and Mazda had other, profitable ranges on sale and so could absorb the cost of fixing failed Cosmos.  Mazda did seem to learn from the NSU experience however.  When they put the Wankel into volume production, the vehicles initially were offered either as a rotary or with a conventional piston engine, an approach which seemed promising but such was the fragility of the Wankel, even that had to be abandoned.  Mazda, after putting Wankels even into small trucks and busses, realised that for consumer vehicles, it was a niche product and restricted it to specialist sports cars.  The problems didn’t go away, but, for a while, they became manageable.

Mazda RX-7 (the Porsche 924-928 inspired second generation (1985-1992) model) in Lindsay Lohan's music video clip First (2005).

The Cosmo's spiritual replacement was the RX7, a two door coupé (there was a short run of roadsters in the second generation) built over three generations between 1978-2002.  With over 800,000 produced, it's probably still the machine most identify with the Wankel engine and was the car which came closest to gaining the mainstream acceptance which had eluded earlier models such as the RX-2 (Capella), RX-3 (Savanna) & RX-4 (Luce), probably because reliability had significantly improved and those buying relatively expensive sports cars were more tolerant of the higher fuel bill and in fairness, much of the competition offering similar performance returned fuel consumption which was little different.  It was replaced by the RX-8 which proved (thus far), the swansong for the Mazda rotary on the streets.     

1972 NSU Prinz 1200 TT.

Remarkably, Audi-NSU, although axing the outdated rear-engined Prinz range, maintained the troublesome Ro 80 in production and despite its thirst it survived even the first oil crisis which killed off so many others.  Although most of the old NSU manufacturing capacity had long been given over to the Audi production line, it wasn’t until 1977 the last Ro 80 was built, the decade’s total production of 37,000-odd a disappointment for a car expected to ship more than that every year.

Despite NSU’s takeover in 1969 in the wake of the problem, even in the early 1970s, many major manufacturers were still convinced the Wankel's many advantages would render the piston engine obsolete and embarked on large, and expensive, development programs.  In this they were encouraged by the legendary optimism and confidence of engineers who so often think any engineering problem can be solved with enough time and money.  However the problems, seal wear, emissions and high fuel consumption proved insoluble and the projects which hadn’t been abandoned didn’t survive the first oil crisis.  Apart from the odd small-volume independent, only Mazda persisted. 

Notable Wankel Moments

1974 Mazda Rotary Parkway 26 Minibus (1974-1976).

The Mazda Cosmo was shown only weeks after the NSU Spider. Twice the capacity of the NSU, it was much more ambitious and though also troubled, its low volume meant the rectification was manageable.  Only Mazda has produced Wankel engines in large quantities and they've offered the power-plant in sports cars, racing cars, sedans, coupés, station wagons, pick-up trucks & buses, the last two perhaps a curious place to put an engine not noted for its prodigious torque.  Others, with varying degrees of success, have put them in automobiles, motorcycles, racing cars, aircraft, go-karts, jet skis, snowmobiles, chain saws, and auxiliary power units.

1976 Mazda RX-5.

Even Mazda, which has at least partially solved most of the problems, currently don't have a Wankel in production; the last, used in the RX-8, unable to meet the latest EU pollution standards.  Despite this, Mazda claim to be committed to the Wankel and the factory say development is continuing, in 2016 showing the RX-Vision, hinting it could be on sale as early as 2020.  The COVID-19 pandemic put that at least on hold and concerns about CO₂ emissions may mean the Wankel's historic automotive moment, which lingered for so long, may finally have passed so whether Mazda really solved the problem of toxicity may never be known. 

1975 HJ Mazda Roadpacer (HJ & HX, 1975-1977).

Even Holden fans, as one-eyed as any, don’t have fond memories of the HJ Premier.  Usually, all they’ll say is its face-lifted replacement, the HX, was worse.  Its engines strangled by the crude plumbing used in the era to reduce emissions, driving an HX wasn’t a rewarding experience so there might have been hope Mazda’s curious decision to use the HJ (and later the HX) Premier as their top-of-the range executive car, complete with a smooth two-rotor Wankel, might have transformed the thing.  That it did but the peaky, high-revving rotary was wholly unsuited to a relatively large, heavy car.  Despite producing less power and torque than even the anemic 202 cubic inch (3.3 litre) Holden straight-six it replaced, so hard did it have to work to shift the weight that fuel consumption was worse than when Holden fitted their hardly economical 308 cubic inch (5.0 litre) V8 for the home market.  Available only in Japan and sold officially between 1975-1977, fewer than eight-hundred were built, the company able to off-load the last of the HXs only in early 1980.  The only thing to which Mazda attached its name not mentioned in their corporate history, it's the skeleton in the Mazda closet but does have one place in history, the footnote of being the only car built by General Motors (GM) ever sold with a Wankel engine.

Mercedes-Benz C-111 (1968-1970 (Wankel versions)).

Although the C-111 would have a second career in the late 1970s in a series of 5-cylinder diesel and V8 petrol engined cars used to set long-distance speed & endurance records, it's best remembered in its original incarnation as the lurid-colored ("safety-orange" according to the factory) three and four-rotor Wankel-engined gullwing coupés, sixteen of which were built.  The original was a pure test-bed and looked like a failed high-school project but the second and third versions were both finished to production-car standards with typically high-quality German workmanship.  Although from the school of functional brutalism rather than the lovely things they might have been had styling been out-sourced to the Italians, the gullwings attracted much attention and soon cheques were enclosed in letters mailed to Stuttgart asking for one.  The cheques were returned; apparently there had never been plans for production even had the Wankel venture proved a success.  The C-111 was fast, the four-rotor version said to reach over 300 km/h (190 mph), faster than any production vehicle then available.

Herr Wankel’s personal R107 (350 SL) fitted with 4 Mercedes-Benz Rotor Wankel (KE-413).

Less conspicuously than the C-111s in lurid safety orange were the roadsters which Mercedes-Benz used as Wankel test-beds.  The first used the W113 (1963-1971) platform, remembered now as the first “pagoda” and while it would never have been suitable as a production car, it apparently wasn’t as unbalanced as the sole W113 fitted with the 6.3 litre (386 cubic inch) M-100 V8 used in the big 600 Grossers and the 300 SEL 6.3 which the test drivers described as "exciting but unstable".  Still, the Wankel W113 proved quite a bit faster than the 280 SL and as a proof of concept was judged a success.  The W113 though had never been intended to use anything but a straight-six whereas the successor W107 (1971-1989) was designed from the start with an engine bay and transmission tunnel which would accommodate either a V8 or the Wankel with its high central power take-off.  The W113 had used a three rotor unit (M 50 F) but R107 had four (KE-413) and delivered considerably more power than the 3.5 litre (215 cubic inch) & 4.5 litre (275) V8s used in the production models and not until the adoption of 5.0 (305) & 5.5 (339) V8s in the 1980s would the performance be matched.

Four rotor Wankel engine (KE-413, left) and the unit installed in Herr Wankel’s 350 SL.

Yet however successful the proof of concept may have been, the early skepticism mentioned by the combustion chamber specialists was vindicated because as they pointed out the chamber was "...the central feature of the combustion engine.  The priority is to produce an optimum design so as to achieve the most favorable thermodynamic efficiency."  By that they meant "...as complete combustion of the fuel as possible” and not only was this not happening with the Wankel, their point was that fundamental aspects of the design meant it could not happen, something which manifested in high fuel consumption and difficulties in meeting the exhaust emission standards due to all the non-combusted hydrocarbons.  Modest in their demands in the early 1970s, the US regulators had already provided a decade-long roadmap which would make the rules so onerous there was then no realistic prospect the Wankel could ever be made to comply.  The engineers were confident they could produce a smooth, reliable and powerful Wankel, albeit a thirsty one, but knew they could never make it clean.  All of the factory’s W113 & R107 test-beds were scrapped when the project was cancelled but Felix Wankel’s personal R107 SL survives.  He obtained a four rotor unit from Mercedes-Benz, had it installed by technicians at his institute and in 1979, the trade journal Auto Motor und Sport published their road-test of the unique machine, reporting a 0-200 km/h (120 mph) time of 25.9 seconds and a top speed of 242 km/h (150 mph).

Citroën GS (GX) Birotor (1973-1975), Frankfurt Motor Show, August 1973.

Sometimes one gets lucky, sometimes not.  In the US, Ford introduced the new, small and economical Mustang II a few weeks before the first oil shock in 1973 and had a big hit (something sometimes forgotten by those who so decry the Mustang II and condemn it a failure).  In Australia, about the same time, Leyland announced the big new P76, a selling point its V8 engine.  The P76 wasn’t without faults and may anyway have failed but the timing didn’t help and it didn’t last long, shortly taking with it whatever remained of Leyland Australia.  In France, in October 1973, the very month in which events in the Middle East triggered the first oil shock, Citroën's thirsty GS Birotor went on sale.  Shown at the Frankfurt Motor Show in August, the reception had been generally positive, most complaints being about the aesthetic; all the Birotors appeared to be painted in shades of brown, a color which seemed to stalk the 1970s.

Mechanically though, even before going on sale, some with high hopes for the Wankel were disappointed, the Birotor not realising the promise of smaller, lighter packages.  Despite the compact size, the engine would fit in the GS’s engine bay only transversely so Citroën’s signature inboard disk brakes couldn't be used for the first time since the pre-war Traction Avant. That necessitated a different subframe, a wider track, and bigger wheel arches than the standard GS.  Combined with other detail differences, it bulked the rotary-powered GS up to 690 lb (290 kg) more than the standard GS, compelling the addition of anti-roll bars to reduce the increased propensity towards body roll.  Another mechanical aspect not much discussed at the time was the Wankel's high exhaust emissions.  In one of many possible illustrations of how the politics of the matter has changed, it was a time when the exhaust pollution rules imposed by the United States appalled Europeans because of the way they made the detoxed cars behave.  Not wishing to sacrifice power, in Europe, drivers for years enjoyed un-emasculated engines and accepted the higher emission of CO₂ and other pollutants as part of life.  Widespread interest in climate change, then the concern of a handful of specialists looking at what was called the "greenhouse effect", was a generation away.  Despite cubic money being spent, it was one aspect of the Wankel that was never fixed and was the final nail in the coffin of Mazda's RX8.    

Known also as the GZ, the Birotor replaced the noisy but robust and economical air-cooled flat four used in the GS on which it was based and cost about 70% more.  The Wankel engine was the first fruit of the NSU-Citroën joint venture and, being of small capacity, attracted lower taxes than a similar piston-engined car.  However, it suffered the problems endemic to the Wankel: ruinously high fuel consumption and chronic unreliability caused by wear of the rotor seals and the damage this caused to the housing walls.  Citroën had looked at the Ro 80's issues and had included an additional oil pump to improve seal lubrication but the problems persisted.  Internal documents later revealed that just as at NSU half a decade earlier, there were those within Citroën who understood, long before the release, that a disaster was impending but a combination of corporate inertia, an unwillingness to admit failure and a number of contractual obligations meant the Birotor went on sale.  Within months the extent of the problem was realized.  Although only a few hundred had found buyers, broken ones were being towed to dealers around the country and owners were irate.  Early in 1975, Citroën dropped the model, offering to buy back all the 847 made, running or not, customers given a full-refund.  Most agreed and Citroen scrapped every one they could, hoping everyone would forget they ever existed.  A remarkable third of owners declined the offer and many survived in private hands; among Citroën aficionados they’re a collector’s item though probably more displayed as a curiosity than driven.

A twelve-rotor motor intended for marine applications.

The low weight, compact profile, small number of moving parts and very high specific output of the Wankel has always attracted engineers.  The Wankel turned out to be well suited to applications where it could be maintained at a constant speed for long periods, the problem of unburnt fuel in the exhaust substantially resolved, improving emissions and fuel consumption.  Wankels lose efficiency dramatically when they are revved up and down as they are in the normal use of a passenger car but in boats and aircraft where engine speed tends to be constant for long periods, they can work well.  In airframes especially, where weight is so critical, the inherent advantage of the vastly superior power to weight ratio can be compelling.

1989 Norton 588.

One of the many companies to purchase a licence from NSU was English motorcycle manufacturer BSA (British Small Arms) and this became the property of Norton when it absorbed BSA in 1973.  Norton’s troubled history in the 1970s had little to do with the Wankel but after bankruptcy, it was revived on more than one occasion and during one of those escapades, it made almost a thousand Wankel motorcycles.  Other manufacturers dabbled with Wankels and Suzuki actually made some 6000 RE5s between 1974-1976 but the best of the breed were thought to be the Nortons, even though they were admitted to be early in the development cycle.  The Wankel was a more reliable thing by the time the Nortons were made but they suffered the underlying problem of all road-going applications: the advantages just weren’t enough to outweigh the drawbacks, added to which, piston engines continued to improve.  Norton allowed the project to die but did use the Wankel technology to develop a line of UAV (unmanned aerial vehicles, sometimes called drones) engines that proved successful; weighing only 22 lb (8.2 KG) yet producing 38 bhp (28 kw) they proved ideal for the task.

1972 Chevrolet Corvette XP-895 Prototype.

In 1972, spooked a bit by the news Ford would be offering the mid-engined De Tomaso Pantera through Lincoln-Mercury dealers, to steal a bit of the thunder, Chevrolet dusted-off and displayed a mid-engined Corvette prototype, production of which had been cancelled because of the cost.  It was shown again in 1973, this time with a four-rotor version of the Wankel GM had been developing in a number of configurations.  After the Wankel project was aborted, there were plans to use the body with a V8 to replace the existing Corvette, a release penciled in for 1980 but again, costs and concerns about sales potential aborted the idea.  It meant the already long-serving Corvette stayed in the line for fifteen years, not replaced until 1983 and not until well into the next century was a mid-engined version released.