SMALL WONDER

L.J.K SETRIGHT

From: Car Magazine - January 1967

 

Once upon a time there was a Phoenician princess whom Zeus seduced by disguising himself as a bull. On him she rode all the way to Crete, where she bore Minos, and Rhada­manthus, and - Sorry, that was different Europa, and a differ­ent kind of bull. This is the story of a delicate little slip of a thing from Norfolk, in whose belly turns the product of a clandestine alliance with a Frenchman, so that she must now be driven out of her native land. This sad little Story shows how unjust are the ways of the world, for her fast and sophisticated sister, freely available (at a high price) to all who desire to ex­perience the excitement she can offer, is allowed to remain at home and flaunt her derriere in the faces of those who pur­sue her, and has already dis­played herself able to outstrip her most accomplished rivals.

 

The Europa of Zeus was mythical but the Europa of Lotus is hard fact. Getting hard facts about it is far from easy, however, even when you go to its designers for them. The trouble is that, like so many cars today, it is the result of team­work, with only the team boss knowing all the answers and he away on the other side of the world for the Tasman racing season. But my visit to the new Lotus factory at Wymondham near Norwitch was worthwhile, for as soon as I entered the door I began to see why the Lotus

succeeds in being so small, so light, so close-fitting. The office block there is the ultimate in open planning - one huge room, splendidly lit, beautifully ap­pointed, with clusters of desks and drawing boards for all the commercial and design staff, and with doors opening into the workshops. And did you know, the designers and development engineers are all little men, trim and slim and bantam-sized like Chapman himself? Small wonder that when I levered myself into the Europa I found its headrest behind my shoul­ders, my head up near the roof.

 

Small wonder: is that the Lotus in a nushell? Chapman has always worked on the basis of making his cars ultra-light ultra-low-drag affairs with refined suspensions, end then seeing what sort of engines and gearboxes, doorknobs and window-winders, he can get at bargain rates. He certainly hit a good bargain with Renault for the Europa: along with the en­gine and transmission come a number of other oddments like the radiator fan and the door locks. The engine itself is a commendable thing, not to be dismissed as something merely cheap. He shopped around for some time, and In fact toyed with several alternative engines as possible power plants, including the Hillman Imp.

 

 

Renault’s R16 is no ball of fire in ordinary trim. A power output of 58.5bhp is unlikely to make even something of Lotus proportions go very quickly. But, for the Europa, Renault raise the compression, install bigger valves and a fiercer camshaft, slap on a different carburetor, and up goes the output by a third. Immediate evidence under the lid of the engine compartment is the row of holes drilled along the intake pipe for the air cleaner, to allow more air to enter; a closer look reveals yet another intake pipe added dia­metrically opposite, to ensure that the 60 horsepower air cleaner does not strangle the 82 horsepower engine. There will be 100bhp before very long.

 

A look at the tachometer gives further clues. The standard R16 gives peak power at 5000rpm; the Lotus version peaks at 6000 and may be taken briefly to 6500. The crankshaft satisfies current fads in having five main bearings, an arrangement that is not always as good as it sounds; but the crankcase is a splendid example of struc­tural stiffness. Most crankcases are stiff enough in the plane of the cylinders, but very often they are much more flexible (perhaps five times more) in other planes. Sometimes the crankcase walls and flanges, and also the main bearing webs, are carried down below the main bearings in order to add stiffness; sometimes the crankcase is given external ribbing or box-section reinforcement for the

same purpose. The R16 block is a pressure die-casting in light alloy, and it has all the ­features: exterior stiffening abounds, for that is the easy way to do it in die-casting, and the skirts are as deep as the Empress Josephine’s. This counts for a lot in any engine with only four largish cylinders, for such engines suffer much greater bearing loads and deflections than engines of similar power and size but more cylinders. Even so, the Renault crank is limited to 6800rpm, the valve springs being arranged to lose touch with the cams at that point. This allows the engine to hold together and the Renault warranty to hold good.

 

In the Lotus 47, the racing version of the Europa, the engine is the twin cam Lotus Ford with fuel injection; it is also strong, not because it is as clever but because it is much more massive. It is bolted firmly into the chassis, where it adds torsional stiffness - it such a tight fit that it could not be allowed to rock anyway. Cur­rent GP cars have rigidly mounted engines, but the old front-engined GP Lotus 16 had its Climax on flexible bearers (Gad! Does Doctor Kinsey know?), and the chassis tubes had to be bent (bad, that, in a spaceframe) in order to clear the carburetors at full rock. The Renault has to be mounted flexibly, in order to isolate the inevitable four-cylinder vibration, so it is hung on a pair of modi­fied Anglia bearers at each side, with a standard Renault rubber et the tail of the gearbox. This brings fresh problems: the drive shafts act as upper links in the suspension, the lower links are pivoted beneath the gearbox, but the radius arms are located on the chassis. Only with diffi­culty have the awkward inter­actions between suspension and engine-wobble been eliminated. The pivots for the radius arms, well forward on the chassis, embody some very bunjee rubber that also helps to give longitudinal compliance to suit the radial-ply tyres.

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These tyres are 155 x 13 Dunlop SP41. This size was only recently arrived at, for original trials were done with SP41s and Firestone F100s both of 165 section. They were all right, but a bit too good in resisting the imperfections of the steering and suspension geometry instead of flexing to accommodate them, so the more slender and compliant 155 section replaced them. Radials are in any case much less sensitive than cross-ply tyres to vari­ations in camber, so they come in handy on the Europa, whose front end in particular is not terribly precise. This is not en­tirely the fault of the Alford and Alder Triumph-style compon­ents that figure so widely in it, for the upper wishbone is spec­ial and could have been arranged to keep the outer front wheel mount nearly upright on corners. Apparently the trouble was that the pedals got in the way of the steering rack, which could not be poisoned quite ideally. The result is that a bit of extraneous steering is introduced by sus­pension movement. At least, that is what I was told by one of the young, neat, Chapman-­sized engineers to whom I talked at Wymondham. The other, of apparently equal age, precision and size, was sure that the problem had been over­come by raising the wishbone pivot axes, for it is the height of the steering rack, that is most critical, its position in the fore and-aft sense being somewhat less important.

 

Once or twice these two top men were at variance. If Chap­man picks them by size, at least he doesn't brainwash them! It was not easy to tell which was giving me pucks facts end which was resorting to bull; I talked with them severally rather than jointly. Tweedledum said that the torsional softness of the basic spinal box in the frame was something like 5000lb ft/deg, falling off rapidly in the arms that fork to each side of the engine so that the overall stiffness was akin to that of the more cruciform Elan frame. Tweedledee thought the frame stiffness was only about 1400lb ft/deg (Lotus claimed 4500 for the Elan when it was introduced) in the Type 47 racing version, whose rear hoop-like bulkhead gives it perhaps 10 percent more stiffness than the frame of the Type 46 road Europa with its simple transverse bracer.

 

 

Anyway, there are in life other things than torsional stiff­ness. Our Mr. Moss put in a record lap in the Brussels GP in 1961 driving a Lotus whose frame had a torsional stiffness of only about 300lb ft/deg! Everyone says that stiff frames go with soft springs, pliable frames with hard springs - but that type of Lotus had just about the softest ride in racing, with spring frequencies of about 60c/sec. Nowadays the GP cars are up again to about 82c/sec, and the Europa’s racing sister the Type 47 has 100c/sec springs front and rear (some slight differential is usual to avoid pitching difficulties). So what about Europa proper, the Typo 46? The answer is about 69-71, the same as the Elan. The Type 46 is lighter than the Elan, and because of this it has apparently not been able to give quite so good a ride; but a ride nearly as goad as the Elan's is still very good indeed.

 

The Elan had to be a lot cheaper than the Elite. Now the Europa has to be a lot cheaper than the Elan. It shows in some details: the rear brakes are drums from Triumph, and have to be equipped with high ­friction linings and an oversize cylinder (0.75in rather than 0.71 to get somewhere near balanc­ing the power of the front discs. At least this helps the handbrake. Money has been saved in other departments too: trim is vestigial, finish elemental, bum­pers are Ford, and the Europa buyer saves the cost of a radio because the grp (glassfibre to you) body is so transparent to interference as to make the fitting of radio a waste of time. Do not despair; Tweedeldum is working on it right now.

 

One thing Lotus have not skimped is the provision of sound-deadening. With the cylinder head inches from the driver's ear this is imperative. There is an inch-thick layer of felt backing the body diaphragm that separates the engine room from the wheelhouse, and quantities more of similar stuff around the back­bone tunnel. This tunnel contains several services – hot and cold water, hydraulic pipes, wiring, etc – and is fairly effectively sealed at each end to prevent draughts finding their way into the cockpit. Virtually the only air to enter comes from the nose intake, passing via a Ford heater fan to a plenum chamber ahead of the facia. From this chamber it may continue cold through Renault butterfly-nozzles in the facia, or it can negotiate a central duct that leads it through a heater matrix.  The plenum chamber is also a luggage compartment, but even when apparently full of luggage it still allows the air to circulate. There is another luggage box of very generous size in the tail of the car.

 

Felt, heater system, luggage boxes and such things add up to a surprising lot of weight. The absence of these things from the Type 47 explains why this car weighs less than the Type 46, despite a heavier engine. You see, the R16 engine is very light: in standard form it weighs only 203lb, giving a specific engine figure under 3.5lb/bhp that comes down to about 2.5 in the Lotus version. Even complete with transmission, the thing only scales about 265lb. The Ford is quite a bit heavier, and the racer also has the additional burden of more complex suspension and big rear hub carriers carrying disc brakes – it is in fact the first Lotus to have the rear discs in the semi-inboard position, between outer universal and hub carrier, where they can be cooled more easily. The suspension is essentially similar to the type 41, which in case you have lost count is the Formula 3 car: and Tweedledee was standing no nonsense about imperfect geometry at the front of this one. The pedal assembly is the usual racing kind, with three pedals hanging from a carrier that also supports the three hydraulic master cylinders – clutch, brakes and brakes, front and rear systems being coupled by a balance beam – and the whole lot slides on runners for reach adjustments. The apparatus does not get in the way of the steering rack, which is precisely where it should be.

Other details of the racer include obvious things like an oil cooler in front of the fanless water hear exchanger, right-hand drive instead of left, a pair of light alloy 10 gallon fuel tanks, magnesium wheels with vast 8 ½ and 10in rims wearing Firestone 13in tyres, and transmission by Hewland. The bodywork is thinner, but still strong enough to stand being driven into straw bales and things (thinks of everything, does ‘dee), and is bonded to the chassis to make for a bit more stiffness. The racer is just a bit more tail heavy than the Type 46, which has a front/rear distribution of about 45/55, just like all the best GP cars of the last 15 years or so regardless of whether their engines came before or behind the driver.

 

It is in having the engine aft that the Europa is so special, of course, Chapman has been toying with the idea for years, who has not? – and it is long overdue, though goodness knows he has had plenty of other things to keep him busy. In a single-seater the rear-engine layout has been obviously preferable for a long time, but the advantages are not so clear with a two-seater. In the first place, a prop shaft can pass down the middle between the seats, so the elimination allows no saving of frontal area as it does in a single-seater. In the second place, it is usually easier to find enough room for an engine between the front wheel arches than it is to find room for two pairs of feet. In the third, plumbing is easier with a front engine, especially for heaters. But the Europa is 4in lower than the Elan, significantly lighter, and there is no cramping of the feet. Maybe the wider track is the answer, but the Elan at 47.5in was always a bit narrow-gutted anyway: with GP cars reaching out to 60in tracks, the 53in of the Europa seem reasonable and proper. What is more, the vacant bonnet can be made a lot lower, doing great good by giving better penetration of the air. Remind yourself that the drag coefficient is sometimes called the coefficient of penetration, and the picture becomes clearer: the most significant thing about the Europa is the very low aerodynamic drag of the body. As a production car the Europa is in a class of its own: the Citron DS is unusually good at 0.38, the Porsche even better, the Elan belies it’s appearance with a wholly creditable 0.34, but the Europa puts them all into the blunt instrument category, its drag coefficient working out to within a whisker of 0.3.

 

This drag coefficient business needs a spot of clarification for the figure can vary quite a lot according to how it is obtained. If a full size car  is tested in neutral conditions with a calibrated engine and transmission then there is no doubt about the result: but wind-tunnels can give rise to unjustifiable optimism. In particular, the way that the road is represented can make a big difference to the figures. If the wind-tunnel model is mounted on a flat plate, the boundary layer behavior is not to scale: do with the road surface altogether, and vortex formation behind the vehicle is affected: place two identical models with all wheels touching )the ‘mirror image’ system) and turbulent flow between them spoils the results, while, although theoretically perfect, the representation of the road by a sort of roller blind is beset by practical difficulties in stopping it flapping. One way or another, results can vary by 10percent.

 

The Europa was tested as a quarter-scale model in the MIRA tunnel, correction factors for which are known, and the resultant figure of 0.3 will not be far adrift. The same tunnel gave 0.33 for the Elan, which turned out to be a genuine 0.34, for example. One of the things that cannot be checked with a model is the drag losses in the cooling system, which in most cars amount to about 30percent of the total, as the wind goes through the radiator and blasts around under the bonnet looking for the way out. The Europa has s completely ducted system that exhausts into the low-pressure region inside the right front wheel arch, and is likely to prove even better than other ducted systems which have been known to reduce cooling dorag to below six percent of the whole.

 

The shape of the nose isn’t everything. The roof line, the window contours (the prototype had Perspex side windows whose shape Triplex are unable to match in glass) and the tail are all of importance. Especially the tail: Lotus found that the low-pressure area between the rear window was causing a breakdown in flow, so they stuck a shallow transverse spoiler across the rear edge of the afterdeck, put some holes in the deck lid for air to flow up from the engine room, and pronounced themselves well pleased with the results. Those high rear quarters, tantamount to fins, will do a good job of keeping the center of pressure from creeping forwards at high speed, so directional stability should be food even in crosswinds.

 

According to Motorcar, the drag coefficient (Cd) of the Europa is 0.29. Tweedledum thinks somebody got them at cross purposes: apparently there was an experiment made with a Persplex fairing that extended the roof line backwards to about the plane of the rear axles and reduced the coefficient to 0.295. Setright is pleased to offer this as a gratuitous demon tweak for the racing fraternity.

 

Let us not, however, run away with the idea that, because the Europa is so much better than everything else at present, it is an all time best. Decades ago, when Chapmen was a little boy, Daimler Benz modified a Mercedes Benz 158 saloon in ways that brought the Cd down from 0.55 to 0.295. Earlier still, Professor Kamm’s K-Wagen (a specially modified bodied 3.5litre BMW) registered 0.23. The Germans have always been good at this, both I practice(the VW Beetle is surprisingly good) and in theory: the experimental Gottingen car had a Cd of only 0.19. But beggars cannot, according to the axiom, be choosers: of all production cars the Lotus Europa is outstanding: and in one respect it is superior to all the old-time wonder cars, for it has much smaller frontal area. It must not be overlooked that a reduction in frontal area gives precisely the same benefits as a corresponding reduction in drag coefficient, with fewer directional stability problems entrained.

 

What, in sum, is it all worth? Even taking the somewhat flattering view that 0.4 is a representative Cd for current cars, the Lotus profits from its shape (assuming unchanged frontal area and weight) to the extent of needing 18percent less tractive effort at 100mph. At other speeds the difference will be of similar magnitude but not quite the same, because of the complications of rolling resistance. Put another way: on 82bhp the Europa could go jolly fast. In fact, it is undergeared with acceleration in mind, but economy at part-throttle cruising should be its strong suit. It all puts me in mind of the observations of Mr. D. W. Sevier in a 1954 ImechE  paper on aerodynamics: ‘Since an external form with a Cd of 0.21 is will within the realms of scientific development, and could be acceptable to the public.   .it seems that a car (with a Cd of 0.4) which is fairly representative of present day light fast cars needlessly donates 23percent of its available power to the dictators of fashion’.

 

In Britain, dictators of a different sort make anything over 70 illegal but even at this absurd speed the good shape of the Europa will aid acceleration. It is not simply the power/weight ratio that determines acceleration at other than very low speeds: what counts is the ratio of weight to surplus power available. With a low-drag body the surplus is much more substantial, and the Europa should reach its frantic flat-out 6500 in top (115mph actually) very briskly indeed.

 

I hope it is as brisk in going into production. Tweedledum was bemoaning difficulties that stood in the way: component suppliers who were unable or unwilling to hold specified tolerances were one of his biggest bugbears. There are sundry other odds and ends to be cleaned up: the lower extremities of the rear hum carriers must be cropped to give a better ground clearance and at the same time improve the look of the rear by getting the bottom suspension link higher; final arrangements have to be made for the heater fan; there is electrical screening to consider. And what about a brake servo? Pedal pressures are getting rather high at 110lb of 1g. Chapman likes to save money and add reliability by eschewing servo aids, but doing it all by high-friction linings can be expensive and unstable: anyway the Type 46 has to have the hardest possible linings for the front brakes in the interests of optimum balance.

 

When these things are sorted out, or possibly before, production will gradually quicken. Not that it will matter to us for a year or so, since only foreigners (which does not include Americans, strange as that may seem) will at first be allowed to buy the Europa. ‘Contrariwise,’ continued Tweedledee, ‘if it was so, it might be: but as it isn’t, it ain’t. That’s logic.’ What he meant is that if you have £2600 you can order a Type 47 rhd racer right now.