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.
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.
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.
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 cm
3 (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.
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.
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 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).
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.
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.
