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Monday, July 31, 2023

Penthouse

Penthouse (pronounced pent-hous)

(1) An apartment or dwelling on the roof of a building, usually set back from the outer walls.

(2) Any specially designed apartment on an upper floor, especially the top floor, of a building.

(3) A structure on a roof for housing elevator machinery, a water tank etc.

(4) Any roof-like shelter or overhanging part.

(5) In Real Tennis, a corridor having a slanted roof and projecting from three walls of the court.

(6) As mechanical penthouse, a floor, usually directly under a flat-roof, used to house mechanical plant & equipment.

(7) A special-interest magazine, aimed at a mostly male audience and published in several editions by a variety of owners since 1965.

1520–1530: Despite the appearance penthouse is not a portmanteau (pent + house) word.  Penthouse is an alteration (by folk etymology) of the Middle English pentis, pentiz & pendize (and other spellings), from the Old French apentiz & apentis (appendage, attached building), the construct being apent (past participle of apendre (to hang against)) + -iz (the French -is ) from the unattested Vulgar Latin –ātīcium (noun use of neuter of the unattested –ātīcius, the construct being the Latin -āt(us) (past participle suffix) + -īcius (the adjectival suffix)).  Old French picked up apentis from the Medieval Latin appendicium (from the Classical Latin appendo (to hang) & appendere (to hang from).  A less common alternative variant to describe a shed with a sloping roof projecting from a wall or the side of a building was pentice.  Penthouse is a noun; the noun plural is penthouses.

1965 Iso Grifo Bizzarini A3/C, Le Mans, 1965.

One of the most admired of the trans-Atlantic hybrids of the post-war years (1945-1973) which combined elegant coachwork, (hopefully) high standards of craftsmanship and the effortless, low-cost power of large-capacity American V8 engines, the Iso Grifo was produced between 1965-1974 by the Italian manufacturer Iso Autoveicoli.  Styled by Bertone’s Giorgetto Giugiaro (b 1938) with engineering handled by the gifted Giotto Bizzarrini (b 1926), the Grifo initially used a 327 cubic inch (5.3 litre) version of the small-block Chevrolet V8, coupled with the equally ubiquitous Borg-Warner four & five speed manual gearbox or robust General Motors (GM) automatics.  Later, after some had been built with the big-block Chevrolet V8, GM began to insist on being paid up-front for hardware so Iso negotiated with the more accommodating Ford Motor Company and switched to 351 cubic inch (5.8 litre) versions of their 335 (Cleveland) engine.

1955 Iso Isetta.

Iso was already familiar with the mechanical configuration, production of their Rivolta coupe, equipped also with the Chevrolet 327, having begun in 1962.  The Rivolta, let alone the Grifo was quite a change of direction for Iso which until then had produced a variety of appliances, scooters & moto-cycles, it’s most famous product the Isetta, one of the generation of “bubble cars” which played such a part in putting Europeans back on (three or four) wheels during the re-construction of the post-war years.  Surprisingly, despite the prominence of the Isetta name and the Italian association, barely a thousand were actually manufactured by Iso, the overwhelming majority produced in many countries by BMW and others to which the a license was granted.  Powered by tiny two and four-stroke engines, their popularity waned as “real” cars such as the Fiat 500 (1955) and later the Mini (1959) emerged; although costing little more than the bubble cars, they offered more space, performance and practicality.  By the early 1960s, the bubble cars were driven almost extinct but, as a tiny specialized niche, they never completely vanished and the Isetta is enjoying a twenty-first century revival as model urban transportation, including the option of electric propulsion.

1968 Iso Rivolta.

The Rivolta was thus quite a jump up-market and, while the engine wasn't the bespoke thoroughbred found in a Ferrari or Aston-Martin, the rest of the specification justified the high price.  Unlike some of the British interpretations using American V8s, Iso insisted on modernity, the platform probably the best of the era, the body welded to a pressed-steel chassis, a combination which proved both light and stiff.  Just as importantly, given the high rate of corporate failure among those attracted to this potentially lucrative market, it was cost-effective to manufacture, reliable and easy to service.  Probably the feature which let it rank with the most accomplished of the era was the sophisticated de Dion rear suspension which, combined with four wheel disc brakes, lent it a rare competence.  The de Dion design was not an independent arrangement but certainly behaved as if it was and, despite what Mercedes-Benz claimed of their beloved swing-axles, was superior to many of the independent setups on offer.  A noted benefit of the de Dion system is it ensures the rear wheels remain always parallel, quite an important feature in an axle which has to transmit to the road the high torque output of a big V8, a lesson Swiss constructor Peter Monteverdi (1934–1998) applied later in the decade when he went into production using even bigger engines.  Iso, with a solid base in accounting and production-line economics, ran an efficient and profitable operation not beset by the recurrent financial crises which afflicted so many and the elegant Rivolta was a success, remaining available until 1970.  Some eight hundred were sold.

1967 Iso Grifo Series One.

The Rivolta’s platform proved adaptable.  In 1965, Iso released the Grifo coupé, more overtly oriented to outright performance and strictly a two-seater.  With lovely lines and a modified version of the Rivolta’s fine chassis, the Grifo was another product of the fertile imaginations of Giugiaro & Bizzarrini but, in something not untypical in Italian industry of the time, the relationship between the latter and Iso’s founder Renzo Rivolta (1908–1966) soon became strained and was sundered.  Bizzarrini would go on to do remarkable things and Iso’s engineers assumed complete control of the Grifo after the first few dozen had been completed.  Bizzarrini had pursued a twin-stream development, a competition version called the A3/C with a lower, lightweight aluminum body as well as the road-going A3/L and when he decamped, he took with him the A3/C, to be released also under his name while Iso devoted its attentions to the A3/L, again using engine-transmission combinations borrowed from the Corvette.

1964 Iso Grifo Spider.

The Grifo weighed a relatively svelte 1430 kg (3153 lbs) in what must have been a reasonably slippery shape because the reports at the time confirmed some 240 km/h (150 mph) was easily attained, an increase on that managed by the Corvette and, when configured with the taller gearing the factory offered, the factory claimed 260 km/h (162 mph), was possible.  A test in the UK in 1966 almost matched that with a verified 161 mph (259 km/h) recorded and two year later, the US publication Car & Driver 1968 tested a 327 Grifo but didn't to a top-speed run, instead estimating 157 mph (253 km/h) should be possible given enough road.  There were surprisingly few variations, fewer than two-dozen made with a targa-style removable roof panel and a single, achingly lovely roadster was displayed on Bertone's stand at the 1964 Geneva Motor Show; it remained a one-off although a couple of coupés privately have been converted.

1970 Iso Grifo Series Two.

The bodywork was revised in 1970, subsequent cars listed as series two models.  The revisions included detail changes to the interior, improvements to the increasingly popular air-conditioning system and some alterations to the body structure, the hydraulics and the electrical system, most necessitated by new regulatory requirements by some European countries but required mostly in an attempt to remain compliant with the more onerous US legislation.  The most obvious change was to the nose, the headlamps now partially concealed by flaps which raised automatically when the lights were activated.  Presumably the smoother nose delivered improved aerodynamics but the factory made no specific claims, either about performance or the drag co-efficient (CD) number.

1972 Iso Lele & 1972 Iso Fidia.

In 1972, an unexpected change in the power-train was announced.  After almost a decade exclusively using Chevrolet engines, Iso issued a press release confirming that henceforth, the series two Grifo would be powered by Ford’s 351 cubic inch (5.8 litre) 335 series (Cleveland) V8.  In the state of tune chosen by the factory (essentially the same as fellow Italian specialist De Tomaso were using in their mid-engined Pantera), the Ford engine was similar in size, weight to the small-block Chevrolet and delivered similar power and torque characteristics so the driving experience differed little although there were 22 high-performance Leles using a tuned 351, all with a ZF five-speed manual gearbox.  The other improvement in performance was presumably Iso’s balance sheet.  The switch had been made because internal policy changes at GM meant they were now insisting on being paid up-front for their product whereas Ford was still prepared to offer an invoice with a payment term.  The change extended to the other models in the range, the Lele coupé and Fidia saloon and while the Chevrolet/Ford split in the Lele was 125/157, the circumstances of the time meant that of the 192 Fidias made, only 35 were fitted with the 351.

1969 Iso Grifo 7 Litre (427).

One of the trends which made machines of the 1960s so memorable was a tendency never to do in moderation what could be done in excess.  In 1968, Iso announced the Grifo 7 Litre, built following the example of the US manufacturers who had with little more than a pencil and the back of an envelope worked out the economics of simple seven litre engines were more compelling than adding expensive components like overhead camshafts and fuel-injection to five litre engines.  Petrol was, of course, cheap and limitless.  Petrol actually wasn’t as cheap in Italy or the rest of Europe but Iso’s target market for the Grifo was those who either could afford the running costs or (increasingly) paid their bills with other people’s money (OPM) so fuel consumption wasn’t something often considered.  The new version used a 427 cubic inch (7.0 litre) version of the big-block Chevrolet V8, bigger and heavier than the 327 so the driving characteristics of the nose-heavy machine were changed but contemporary reports praised the competence of the chassis, the de Dion rear-end notably superior in behavior compared with the Corvette’s independent rear suspension although some did note it took skill and often a sense of restraint, effectively to use the prodigious power.  Tellingly, the most receptive market for the Grifos, small and big-block, was the Federal Republic of Germany (FRG, the old West Germany) with its network of highways without the tiresome speed limits elsewhere imposed and (even in Italy), often enforced.  The autobahn really was the Grifo's native environment.   

1970 Iso Grifo Can Am (454).

Faster it certainly was although the factory’s claim of a top speed of 186 mph (a convenient 300 km/h) did seem optimistic to anyone with a slide-rule and there appears not to be any record of anyone verifying the number although one published test did claim to have seen well over 255 km/h (150 mph) with the Grifo still "strongly accelerating" before “running out of road”.  It had by then become a genuine problem.  Gone were the happy times when testers still did their work on public roads; increased traffic volumes by the late 1960s meant the often deserted stretches of highway (in 1956 an English journalist had taken a Mercedes-Benz 300SLR Coupé to 183 mph (294 km/h) on the autobahn) were now rare but whatever the terminal velocity, nobody seemed to suggest the 7 litre Grifo lacked power.  In 1970, after Iso’s stock of the by-then out-of-production 427 were exhausted, the big-block car was re-named Can-Am and equipped instead with a 454 cubic inch (7.5 litre) version, the name an allusion to the unlimited displacement Group 7 sports car racing series run in North America in which the big-block Chevrolets were long the dominant engine.  Despite the increased displacement, power actually dropped a little because the 454 was detuned a little to meet the then still modest anti-emission regulations.

1971 Iso Grifo Can Am (454).

Unlike the 427 which breathed through three two barrel carburetors, the 454 was equipped with less intricate induction, a single four barrel and, officially, output dropped from 435 horsepower to 390 but, these were gross (SAE) numbers and Detroit’s high-performance engines in this era were rated at something around what a manufacturer thought would be acceptable (all things considered), rather than an absolutely accurate number but the 454 certainly was just a little less potent than the 427 although it's probable few owners often went fast enough to tell the difference.  What didn’t change between the 7 Litre and the Can Am was its most distinctive feature, the modification to the hood (bonnet) made to ensure the additional height of the 427's induction system could be accommodated.  The raised central section, the factory dubbed "the penthouse".

Penthouse on 1969 Iso Grifo 7 Litre (427).

Not everyone admired the stark simplicity, supposing, not unreasonably, that Giugiaro might have done something more in sympathy with its surroundingsCritics more stern would have preferred a curvaceous scoop or bulge and thought the penthouse amateurish, an angular discordance bolted unhappily atop Giugiaro’s flowing lines  but for those brought up in the tradition of brutalist functionalism, it seemed an admirable tribute to what lay beneath.  The days of the big-block Grifo were however numbered.  In 1972, with Chevrolet no longer willing to extent credit, and Ford’s big-block (429 & 460) engines re-tuned as low-emission (for the time) units suitable for pickup trucks and luxury cars, the Can-Am was retired.  So the small-block 351 Grifo became the sole model in the range but it too fell victim to changing times, production lasting not long beyond the first oil shock in October 1973 which made petrol suddenly not only much more expensive but sometimes also scarce and the whole ecosystem of the trans-Atlantic machines became threatened and in little more than a year, Iso was one of the many dinosaurs driven extinct.  Decades later, the survivors of the 412 sold are highly desirable; fine examples of the small-block Grifos attract over US$500,000, the few dozen penthouse cars can sell for up to a million and the rare early A3/Cs for well over.

Not fans of brutalist functionalism were the Lancia-loving types at Road & Track (R&T) magazine in the US.  Late in 1974, R&T published their 1975 buyer’s guide for imported and domestically-built smaller cars (R&T neither approving of nor understanding why anyone would wish to buy a big American car) and surprisingly, there were reviews of the Grifo, Lele and Fidia although the last of these sold in the US some two years earlier had been titled as 1973 models, the company having never sought to certification to continue sales although, given nothing had been done to modify them to meet the new safety regulations, that would likely have been pointless unless the strategy was to seek a "low volume" exemption, something improbable by 1975.  The distributors had however indicated to the press all three would return to the US market in 1975, supplying publicity photographs which included a Series II "penthouse" Grifo although the big-block cars hadn't been built in Italy since 1972.  A further complication was that during 1974, Ford had discontinued production of the high-performance 351 (the "Cleveland" 335 series) V8 so it wasn't clear what power-train would have been used.  Others had the same problem, De Tomaso (which withdrew from the US market in 1974) switching to use tuned versions of the Australian-built Cleveland 351s but for Iso, the whole issue became irrelevant as the factory was closed late in 1974.  R&T's last thoughts on the penthouse appeared in the buyer's guide:

"However, the clean lines of the original Grifo have been spoiled by that terrible looking outgrowth on the hood used for air cleaner clearance.  For US$28,500 (around US$150,000 in 2024 $ although direct translation of such a value is difficult to calculate because of the influence of exchange rates), a better solution to this problem should have been found."

View from the penthouse in which Lindsay Lohan lived in 2014, W Residences, Manhattan, New York City.

Sunday, July 9, 2023

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.