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.
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.
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.
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. Wholly unrelated to knitting machines, motor-cycles & cars, NSU (non-specific urethritis) was the old term for NGU (non-gonococcal urethritis), an inflammation of the urethra not caused by gonorrheal infection. In post-war Germany, it's used also as the initialism of Nationalsozialistischer Untergrund (National Socialist Underground), a general term for neo-Nazism and other fascist organizantions & movements.
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.
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.
The NSU Spider should not be confused with NSW’s spiders of which there are quite a few. Of the order Araneae, spiders are air-breathing arthropods (the usual reference to them being arachnids is a bit vague) and Australia is home to many, the most venomous of which is the Sydney funnel-web (Atrax robustus), found in New South Wales (NSW) in forests as well as populated urban areas. They prefer to burrow in humid sheltered places but it’s not uncommon for them to wander into suburban backyards and sometimes they have to be rescued from swimming pools. Human encounters are however relatively rare but they’re noted for their aggression if a threat is perceived so caution is recommended, their highly toxic venom produced in large amounts and the remarkably large fangs (larger than a brown snake, another of Australia’s many dangerous species) can be deployed with sufficient force to pierce human finger & toenails. Although measuring only 15-35 mm (.6-1.4 inch), their venom contains a compound which attacks the human nervous system & internal organs, a strike from a male able to kill an adult although since anti-venoms became available in 1981, no fatalities have been recorded. The Sydney funnel-web is the deadliest spider in Australia.
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.
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 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.
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.
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
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.
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.
Most Holden fans, as one-eyed as any, don’t
have fond memories of the HJ (1974-1976) Premier. Usually, all they’ll say is its face-lifted replacement, the HX (1976-1977), was
worse. With its chassis not including the "radial tuned suspension" (RTS) which lent the successor HZ (1977-1980) such fine handling and with engines strangled by the crude plumbing used in the era to reduce emissions, driving the HJ or HX really wasn’t a rewarding
experience (although the V8 versions retained some charm) 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 anaemic 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 even 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.
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.
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 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).
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.
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.
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