Wilson's Bedouin Executive GT

From Autocar Magazine, Week ending 17th December 1970



Rather disappointing engine conversion offers small gains in performance and mpg, and requires premium fuel. Tinted windows for a black world. Tape stereo and radio, and a television option, in an £1,892 10s 6d package deal

PROMPTED BY increasing demand for the more expensive motor caravans, Wilsons introduced earlier this year a number of modifications for the Bedford Bedouin coachbuilt design. All the items are available separately, or the whole caravan may be ordered with an even fuller list of options at a total price of £1,892 10s 6d. In this form it is called the Executive and has a distinctive matt radiator grille. There is also, at £100 extra, a conversion for the 2-litre engine. The Bedouin with the Executive specification in full, and with the GT engine, has been submitted by Wilsons Motor Caravan Centre for a brief test.

To deal first with the engine conversion, we must confess to being a little disappointed. The modifications include a twin-choke Weber carburettor, higher compression ratio and revised induction. For the third time in our experience of the Bedford van, the bonnet release catch was not working, so we were only able to see the engine conversion by removing the cowling in the cab. This is enough to show the difficulty which lack of space makes in any attempt to modify the power unit, and the right angle junction in the air inlet cannot do much for efficient breathing. The table shows the small improvement in performance which resulted, and the gain in fuel consumption was offset by the need to use premium fuel instead of regular.

Not apparent from the figures alone is the fact that the vehicle felt much crisper and more responsive, and it was not until performance figures were taken that it was found that the improvements were more marginal than had been expected.

Air silencing was less effective on the modified engine, and a lot of induction hiss could be heard on light throttle openings, changing to a throaty roar under full power. The power brakes are a useful improvement on the Bedouin.

It is surprising how greatly the tinted windows alter the external appearance, but inside the effect is a little funereal, and the interior is very dark. Whatever the weather, you take your own dull day along with you. However, many people will no doubt value the privacy, especially when eating meals in the caravan, when one feels much less like a goldfish in a bowl. We were informed that the suppliers of the tinted glass have been requested to make it less dark on future production.

This is not the first time that a motor caravan has been offered with a tape stereo unit, but one would have thought that one of the combined tape and radio units would have been preferable to the two separate items listed at a total price of £86. Further, the stereo was not working, and both units were out of reach of the driver. Wilson's now offer Sony portable television as an alternative to the tape stereo and the tinted glass which seems a much more sensible option for a motor caravan. When this option is specified the Executive costs £1,869, showing a reduction of £23 10s 6d. There are difficulties of thief—proofing a television in a motor caravan, but half the battle is for the set always to be stored out of sight when not in use.

In the full specification of the Executive there are a number of lesser items, such as a fire extinguisher, gas refrigerator and tax for four months, in the attempt to offer a really comprehensive specification without extras; and the price has been maintained in spite of an increase in the basic cost of the Bedouin.

The idea of tailor—made modifications for a motor caravan is attractive, and there is considerable scope. This is quite a good start, but we would like to see some more practical refinements, such as the pressurized hot and cold water system of the Landliner, a conversion to servo-assisted disc brakes, and a more effective increase in power in future modifications. No doubt Wilson's will be looking again at the luxury market to see what further developments can be made for even greater comfort and refinement.

Rolls Royce make a Wankel

From Autocar Magazine, Week ending 17th December 1970.



Rolls-Royce Make A Wankel

Original two-stage diesel design

By J. R. Daniels, BSc

Alone among British firms, Rolls-Royce have shown an abiding interest in the Wankel principle. After six years of research. details are revealed which shows the originality of their work and its promise for the future

WE have long deplored the fact that Britain's motor industry has chosen, by and large, to ignore the Wankel engine. By following a policy of masterly inactivity they may be saving development effort and leaving themselves the option of taking up the rotary engine if it becomes really attractive; but this sort of approach is at present tightly controlled by the licensing arrangements centred on NSU. The only two British licence-holders to date are Perkins and Rolls-Royce, and only Rolls have done any serious development work. For a long time their approach was shrouded in secrecy, except for whispers that their thinking was highly original and intended primarily for application to military vehicles.

Details of their six—year development programme, however, have recently been given in a paper delivered to the Institution of Mechanical Engineers by F. Feller, C Eng, MIMechE. The story is something of a classic, starting with basic research on modified NSU engines and culminating in the design of a 350 bhp engine for military vehicle use. Even at this stage, Rolls-Royce regard the story as only half-written; much more development will be needed before the projected engine becomes a full production unit, even for the Army, while commercial prospects are even farther off.

The basic Rolls requirement was for an engine of small size and low fuel consumption. Existing standards were set by the opposed—piston two—stroke, and it was decided in 1964 by the Military Vehicles Engineering Establishment that it would be worth trying the Wankel engine as a diesel, for the sake of economy and the ability to operate on a wide range of fuels.

In fact, the Wankel in its familiar form makes a poor diesel. Its geometry makes it difficult to obtain a high enough compression ratio, and the long, thin combustion chamber has a poor surface—to—volume ratio (which results in high heat losses and poor combustion). Changing the geometry to push up the compression ratio results in a much bigger engine and an even worse surface-to-volume ratio, and so another solution was sought. The obvious answer was to pre—compress the ingoing air, by means of a Roots blower, a turbocharger, or a positive-displacement unit. Since the Wankel is itself a positive-displacement machine, the most elegant solution was to run two Wankels in series, as it were, with the first merely serving as a compressor for the second, in which combustion would take place. The first unit would then complete the thermodynamic cycle by acting also as the expansion stage for the exhaust gases.

The compressor stage must actually be larger than the combustion stage, since the initial compression depends directly on the relative size of the two units. In effect, one chamber of the compressor feeds air into the much smaller chamber of the engine proper. The basic compression ratio of the combustion stage is thus multiplied by the ratio of the displacements of the two units.

Physically, the compressor does not have to be very much bigger than the engine to give a multiplication of two or three. Together, the two-stage engine turns out to be little bigger than the equivalent single—stage one (since, as already explained, the latter must be made much bigger to obtain the same compression ratio). At the same time, the two-stage engine has a much better——i.e. lower surface—to-volume ratio.

Work was thus concentrated on the two-stage layout, with a three-rotor design as a back-up. This had separate rotors of simpler design to serve as the inlet compression and exhaust expansion stages. In the event, this alternative was not needed, but after a period in engineering limbo it is now being studied as an advanced exercise by the Royal Military College of Science.

Basic studies

Aside from the design of the two-stage engine, a great deal of basic research has been done on both combustion and on apex seal design. The combustion research resulted from the decision to use direct fuel injection rather than to` have a pre-combustion chamber in the wall of the rotor housing; there were. several design disadvantages, including leakage past the tip seals and difficult starting, which overruled the possible advantages of pre—combustion.

Combustion conditions in a Wankel are very different from those in a conventional reciprocating engine. Instead of the nice, stable column of air in the centre of the combustion chamber, and the very low piston speed around top dead centre when the fuel injection takes place, the chamber and its charge of air are travelling past the injector very fast indeed. These conditions are not necessarily worse for combustion; it was just that the engineers were working in a field where very little was known, compared with the extensive work which had been done on the reciprocating engine. Such work as had been done on the Wankel related to the petrol-burning, spark—ignition engine.

Using a small NSU Wankel engine as a test bed, 30 different combustion chamber shapes were tried, along with six different fuel injector positions. Some of the combinations were incompatible, but even so, over 100 different arrangements were tried before the best chamber shape was arrived at. In this design, the fuel is injected into a relatively wide recess carefully shaped to induce air swirl. Air for the combustion process comes from above the trailing half of the rotor, and squirts into the area through a narrow delivery channel.

It must be emphasized that this research applies to the Wankel in its diesel form, and it remains to be seen how much of it may be applied to the four-stroke petrol engine.

Seal research

While the combustion test work was going on, the little Wankel engine had to be modified to withstand diesel operating conditions. An early change was made from carbon to steel tip or seals, and it was found necessary to make new seal springs out of Nimonic 90 nickel alloy.

Early studies showed signs of misfiring which were soon traced to seal misbehaviour. Since the seals cannot be a perfect fit in their rotor-tip slots, they were tilting and jamming. The solution here (also adopted by NSU before the appearance of the Ro80) was to machine slots in the leading face of the seal to admit high—pressure gas underneath it and force it upwards into contact with the rotor housing. Later, a tendency of the seals to lose contact with the rotor housing as they passed into a lower-pressure area was overcome by recessing the trailing edge of the slots. This resulted in a 30 per cent improvement in low-speed fuel consumption. A further development was the use of a stepped apex seal, retaining the advantages of the recessed slot while also reducing the seal mass.

Again, these studies were carried out with the diesel engine in mind; but it would be surprising if designers of passenger-car Wankels did not take them into account in future.

Engine developments

The first Rolls—Royce development engine was the R1 which was conceived purely as a research tool. With a compressor stage of 1,126 c.c., and a combustion stage of 500 c.c., it produced over 50 bhp and achieved specific fuel consumptions of better than O.5lb/bhp/hour. Among other things, it was used to develop the best inter—porting arrangement between the two stages.

The R2 engine was the alternative three-stage layout, built but not investigated in detail. R3 refers to a combustion stage only, which is being used as a basic unit to build up a range of engines; it has a displacement of 1,216 c.c., and has produced 180 bhp at 4,500 rpm under test conditions.

The remaining engine of which details may be given is the 2—R6. This is a military engine formed of two banks of a two—stage engine. Each high pressure (combustion) stage has a displacement of 1,265 c.c., and is fed by a low-pressure stage of 3,250 c.c. The design power is 350 bhp at 4,500 rpm, for a weight of 939lb-a spectacular power-to-weight ratio for a diesel.

Rolls—Royce emphasize that this engine is not even running as yet, and that it will be some years before it sees even military service. But it is encouraging to see at least one British firm indulging in advanced and original Wankel research.

All the same

From Autocar Magazine, week ending 17th December 1970.

ALL THE SAME

That's the trouble with our cars

By J. R. Daniels, BSc.

What has led Britain's car makers to try to outdo one another in utterly conventional engineering and styling? There has to be a way out, but there are risks involved.

I was driving a Triumph Toledo earlier this year. The car was not to be announced for another month, yet nobody spared it a glance on the road. An isolated experience? Far from it; nobody looked at the HC Viva either, and only two people realized the Hillman Avenger was something they hadn't seen before. In fact, it was obvious that as far as the great mass of the population was concerned, all three cars looked pretty much the same as most other cars.

lf the firms producing them are to be believed, each of those cars represented a unique set of virtues, suiting it best to the needs of many—if not most—family motorists. So why on earth is it necessary for them to look like four peas out of the same design pod?

One is driven to wonder how these cars are to be sold. Since they all look the same to the untutored eye, it can be said that none of them appeals more than the others—none of them will sell itself in the face of the opposition, so to speak. The selling must be done for the car—but how? By undercutting the market? Ridiculous; the economic pressures don't permit it. By dint of superior reputation? l’m sorry, but don't make me laugh.

All that is left are conventional advertising and promotion techniques. For the rest, there's a massive reliance on brand loyalty, still one of the most potent sales factors in this country. Of course, it helps to have the cars available when people want to buy them. Failure in this respect explains some, but by no means all, of the drift towards foreign cars in 1970.

Origins and explanations

There are five British entries in the supposedly hotly contested 1100-1300 family saloon class. The newest Viva is a straight replacement for the old one, continuing the line started in 1963 with the angular HA model. ln many ways, the Viva has been the styling leader for cars in this class throughout most of the past decade.

When Ford's Escort emerged to replace the Anglia, it looked like a slightly crude, bulbous copy of the HB Viva; a pity, because the Anglia had been a distinctive design. What went on under the skin was another matter, but then there are thousands of motorists who are far more concerned with what their car looks like than anything else.

Even though the Hillman Avenger was not a replacement for anything, but intended to give the Rootes—Chrysler faithful a chance to buy something bigger than an lmp and smaller than a Hunter, it emerged looking far too much like a Viva or an Escort. Why? Apparently because somebody had decided that to compete with a car, you have to look like it.

When the Triumph Toledo was introduced, we had our fourth virtually identical car. This body shell had a slightly odd lineage; basically a squashed version of the Triumph 2000, it was treated to a new nose with the near—obligatory little rectangular headlamps. Thus endowed, it looked a good deal more like the other three than had its predecessor, the front—drive 1300. And in so far as the Toledo can be regarded as a Herald replacement, we have yet another case of the "Standard British Small Car" supplanting a highly individual design.

Has nobody the courage to build a car which looks different? Are the customers so regimented that they would refuse to buy something which stood out from the common herd? Well, consider the one car in this class which is different, the Austin-Morris 1100/1300. You can't mistake it for anything else. It was originally introduced as a rival for the Cortina, only the Cortina has grown up so fast that comparisons are no longer apt. Hard—headed fleet managers refuse to consider the Austin-Morris car for presumably good reasons of their own, and yet it still sells in Britain in larger numbers than any other car.

One would like to think that there was a lesson here for all car—builders. Yet the most open of motoring secrets is that the Austin—Morris ADO 28, due to emerge in the first half of 1971, will be a thoroughly conventional car aimed at the fleet market and the conservative user. Engineering aside, would anybody like to bet that the average Briton will be able to tell the ADO 28 from an Avenger or a Viva at 100 yards?

Continental variety

This horrid uniformity seems not to afflict our cousins in the Common Market. The three biggest producers. Fiat, Renault and VW, pursue different lines. Fiat's 128 (and the earlier 124) are stark. clean three-box designs. So was the Renault 8: but the newest Renault, the 12, is a highly individual and a very sensible shape. Volkswagen still depend on the Beetle which is equally individual if not as sensible.

The smaller ECM producers do not slavishly follow one of their big three. Simca's 1100 is a five-door fastback; Peugeot's 204 leans more to the conventional, but only on the surface. NSU and DAF have their own views, and the Citroen GS is the most way-out of all. Only Opel and Ford Germany remain faithful to convention, and they are a special case in several ways. Not only are they American-controlled, but the German market has never much cared for cars as small as this anyway. Opel have done nothing to update the Kadett for several years, while Ford Germany build the Escort to take care of the demand.

The upshot of all this is that the ECM car buyer has a choice of shapes from which to choose. It is not so much a good thing in itself; but it underlines the fact that the cars really are different, encouraging him to shop around intelligently to find the one which suits him best. This in turn must encourage the car builders to look for fundamentally new solutions, instead of fiddling round trying to improve the ride a bit here, keep out a bit more noise there, save a few pounds weight and always—but always—cheeseparing pence off everything.

The styling is no more than the outward sign of a whole attitude of mind. ln many ways, though, styling is the easiest thing to change. lf the designers were willing, they could at least try to make their cars lock different, even if fundamental differences were longer in coming. Somehow we have to break out of the stalemate caused by market research feeding on the results of its own findings.

Not just the styling

It isn't just a matter of finding a pretty shape. People have to sit in those cars for hours at a time, and the Standard British Car just doesn't fit them, especially if they are ill-advised enough to sit in the back. A couple of minutes' sketching should convince anybody that, if they are to sit properly, the back passengers must sit at least as high and preferably higher than the driver. Yet our car roof slopes downwards towards the rear from its highest point over the driver's head (Fig. 1). This is no good from any point of view except that of the conventional stylist. It makes for poor aerodynamics (boundary layer separation can take place at almost any point on the roof), and causes a dreadful headroom problem for the back passenger. In an endeavour to restore some room, several firms seat the rear passenger too low (Fig 1A), so that he ends up in an unstable and uncomfortable knees-under-chin position.

The sensible approach is to have a roof line which rises gently towards the rear, as far as the point where it is aft of the rear passengers' heads. After that, there is much to be said for dropping the line sharply. By doing this, you pin down the boundary layer separation point and stop it shuffling noisily backwards and forwards along the roof. One car which employs just this approach is the Renault 12.

There are various ways of finishing off the back end aft of this sort of roof (Fig 2). One possibility is the reverse-rake window of the old Anglia, which again was a highly sensible design in many ways. Other possibilities are the 'notchback' in the manner of the Simca 1100; the true straight-line fastback; or the more humpy approach seen in the Renault 16.

There seems also to be a universal determination to build cars lower and lower. Taking the Fiat 500 and the Chevrolet Impala as being the smallest and largest practical cars, the Chevrolet is nearly twice as long as the Fiat, and almost 50 per cent wider; yet it is only an inch higher! Every so often we lay hands on something higher—built than average, like the Range Rover. When we do, we are apt to revel in the superb view which makes traffic driving easy, and in the decorum with which the vehicle can be entered. lt is surprising, too, how iittle seems to be lost from the handling, at least where normal, sane driving is concerned.

The same might well be said of performance and fuel consumption penalties caused by the increased frontal area. This may well matter for those few genuine GT cars which are actually
used as such, but is that a good reason for trying to turn honest family saloons into styling imitations of them?

One thing we are all short of is road space. Fig 3 shows (admittedly by using two extreme cases) that the lower the car, the longer it must be to carry the same people in comfort. The first designer to add rather that subtract height will be performing a social service, as well as gaining some useful sales points.

Engineering, too

The Avenger, Toledo and Viva all have four-cylinder, in-line, ohv engines, front-mounted and driving the back wheels. All have live back axles, located by four trailing links. The Toledo and the Viva have similar front suspensions as well—although the Avenger uses MacPherson struts. The Escort lines up pretty well with the other three. Again, it is the Austin—Morris 1100 which offers the alternative of transverse engine, front wheel drive and hydrolastic suspension. The example set by Issigonis with this car has been followed with enthusiasm on the continent. The Fiat 128, Simca 1100 and Feugeot 204 all follow its broad principles, while the Renault 12, Citroen GS, Volkswagen K70 all use front wheel drive, with rumours of Alfa Romeo preparing to follow suit. Back in Britain, we often ask about front wheel drive. The typical answer goes like this: "Ah, but you would see all the front wheel drive development cars we have run! But the cost engineers can never get within £20 of the equivalent conventional car . .

We have heard this from many engineers, (not that we have ever actually been shown the development cars!). What we are still disposed to argue is their definition of equivalent. Front wheel drive cars have inherent advantages in terms of providing decent passenger space. Since they leave the back end free for a good but simple independent suspension, they should ride better as well. lt is also relatively easy to get them to handle and hold the road well, although not as easy as some people thought when the Mini was the only example they had to work from.

True, a conventional equivalent can be produced—but it takes a good deal of engineering, unless your definition of equivalent stops at square inches of car and cubic centimetres of engine. If we are not careful, we alone will remain convinced that front wheel drive is uneconomic. Even the Japanese are getting in on the act, and up to now they have been the epitome of conservatism in small car design. There is, surely, still room for the slightly better car at the slightly higher price?

The market was once full of firms looking for a slot in the market—an unfulfilled need. When it
worked, the formula could be a very successful one: the Cortina, the Rover 2000, the Ford Mustang are pre-eminent examples. Now, it appears, one goes bald-headed for a share in an existing market, hoping that a slight price advantage, a favourable press reception and (with luck) no teething troubles and no strikes will add up to a couple of percentage points gained on the sales front. What one does not do is take anything which might be construed as a risk.

Slot—seeking

Table 1 shows how closely matched are the five British cars in the 1100-1300 class. Wheelbase and track are the really significant dimensions, since they tend to govern the amount of interior space. Overall length is a much less reliable guide, since it can so easily be boosted by an unreasonable amount of boot or an empty stylist-special nose.

It is surprising how much difference to interior space can be made by increasing the wheelbase by a couple of inches. There is of course still scope for ingenuity within a given wheelbase; otherwise the Austin 1100 would be no more roomy than the Escort. Looking at the table, one can see how there is an element of slot-seeking with the Avenger, which is aimed between the Escort—Viva and Cortina-Victor markets. Even so, it comes perilously close to the Hillman Hunter, which appears to be under-sized for its class (Table 2).

ln this class, the Maxi offers an impressive space advantage, though the same cannot be said of the slightly bigger 1800 vis—a-vis the Vauxhall Cresta and particularly the Ford Zodiac. This big—car class, however, is becoming increasingly depopulated; the real Austin—Morris contender is the 3-litre, now on its way out. lt may well turn out that the 1800 is about as physically big as anybody will want a car within the foreseeable future. The really big cars lose a lot of their meaning if they take up more road space without being really commodious inside.

It seems that the tendency of cars to conglomerate into groups has left a hole or two to fill; one below the Escort—Viva group, and one above it: with the growth of the Cortina—the Victor was already quite big—the Avenger is not quite big enough to fall square in the gap. Above the Cortina-Victor, the Austin—Morris 1800 is very well established and not too far above; but it might be worth speculating on the form of a conventional—type car in the same bracket. At the same time, consider whether the Maxi was pitched too close to the 1800 in size, since its dimensions put it much closer to its big brother than to its smaller one, the 1300.

Table 3 shows the main foreign competition in the Escort-Viva class. One or two of the cars—Citroen GS, Peugeot 204 and Simca 1100—-are really large enough inside to qualify
as gap-fillers. It is really their limited engine size which leads to our thinking of them in this
class, but then the ECM attitude to engine size is rather different.

At the bottom of the table, note the three smaller Japanese cars, about the right size to fill the sub-Escort gap. There is a staggering similarity between the three from an engineering point of view, emphasising the extent to which their major firms have pursued a policy of matching development for development.

Table 4 shows some of the main foreign competition in the Cortina-Victor class. One point of interest is that it is in this class that technical innovations——overhead cam engines, independent rear suspensions and so on get a real run for their money: and again, five of the cars have front wheel drive.

Laying down a policy

I long for the day when a policy will be laid down for project engineers, designers and marketing men. It would go some way towards ensuring genuine technical and styling competition, to the benefit (I am sure) of the customer. lt would go something like this:

1) Look for gaps in the market, taking the physical size of the car as the yardstick—and the wheelbase as the main criterion of the car's size.

2) Ensure that the car is recognisable in its own right; try to give the sales people some real interior room to boast about.

3) Achieve comfortable seating by using height. Take the overall height of the preceding model as the absolute minimum for the new car.

4) Introduce sufficient technical innovation to give the sales people a real talking point. It doesn't have to be whole—hog stuff like a Wankel engine and hydrostatic four wheel drive. The trends are already being set, and the introduction of the right advanced feature will set people thinking even if they could never point to it under the bonnet.

My gap-filling projects in table 1 have this sort of approach in mind. I am convinced, for instance, that proper independent suspension has to come, with or without front wheel drive. I cannot really see that the current rash of four—link live axles is anything but a dying fling. Where engines are concerned, l have stuck my neck out and postulated a flat-four and a flat-six linked by a building-block arrangement so that the six is, in effect, one and a half of the four—cylinder unit.

Although Volkswagen and Porsche have carried the flat—four banner for many years, I am also encouraged by the brilliant little engine in the Citroen GS, and the fact that light aero-engines have used this layout almost universally for many years and in power outputs up to 200bhp. What l have not done is to go any further and add shapes to the ideas; although Geoff Howard's essay into the mid-engined sports car, published last week, serves notice that we are ready and willing to indulge in further prompting. It would be nice to think that somewhere, someone in the industry—preferably the British industry—is already thinking in terms of breaking out of his engineering straight-jacket. lf this tirade does anything to help him, it will have served its purpose.

Dubfreeze 2008

The 2008 VW season got underway last weekend with the annual Dubfreeze event in Staffordshire. It's a swapmeet with trade stands and a small show and shine indoors, but as is often the case all the most interesting stuff was outside in the car park.

Click for the gallery...

This twin-engined Mk1 Golf was fantastic:


A few non-VW gems lurked about, including this Triumph TR6:


and this Cortina Lotus:


The year really gets going with the Easter Thunderball at Santa Pod, can't wait!