The Editor Recalls Some Attempts to Get Rid of the Reciprocating Engine
With the Turbo-cars very much in the news and the hum of gas-turbines in aeroplanes a familiar daily sound, it seems odd that all attempts to market a pure turbine-car have so far come to naught, although Chrysler listed one for a while. The Wankel rotary engine is to be found under the bonnet of a 1979 Mazda which you can purchase as it once was in NSU models, and, as I have just observed, exhaust-driven turbines to drive superchargers of piston-engines are becoming increasingly the in-thing. But in spite of much highly commendable experimental, and some development, work, the true turbine has only once, to my knowledge, been installed in a car available on the open market (the Chrysler). That has not been for want of trying, as I hope to show.
During the last war Germany investigated the possibilities of using gas-turbines instead of piston-engines in her heavy tanks and special military vehicles. The ability of the gas-turbine to consume low-quality fuels in a unit giving a power:weight advantage must have seemed attractive. Especially as there were some additional benefits, like a simple installation, saving time and cost in its manufacture, easy to maintain and dispensing with a complicated transmission system. If the economy-objective heat-exchanger was not used, the gas-turbine could be expected to be less vulnerable than a piston-engine and much easier to install and remove. Alas, dust was the enemy of the turbine in military usage, for the turbine draws in some ten times the weight of air that is required by a piston power unit, causing rapid wear factors.
It seems that German authorities, looking for a 1,000 h.p. unit, tried five different schemes. There was also a private-venture 320 h.p. turbine intended for vehicle installation. The end of the war came too soon to exploit any of these, but a BMW combustion chamber was made for one of them. So it was in Britain, and at the Rover Company of Solihull, that the next advances were made. Rover’s had been entrusted with developing the pioneer Whittle jet-propulsion units and they later made aircraft turbines until Rolls-Royce took over, because Rover’s were required to manufacture tank engines. They had already produced a straight-through combustion system superior to the former reverse-flow pattern, in conjunction with Joseph Lucas Ltd. After peace had again broken out, Rover’s got down to a vehicle gas-turbine unit. It was intended for the production Rover 75 chassis, to replace its six-cylinder piston-engine. The turbine measured 34″ x 20″ x 18″, weighed 475 lb. (a saving of some 300 lb. over the complete piston-engine and gearbox), this weight including the turbine’s built-in 20:1 reduction-gear. This two-shaft turbine ran at 55.000 r.p.m., later reduced, and it developed about 100 b.h.p. This was a significant break through, especially as Rover’s were sufficiently confident to submit their first gas-turbine car – JET 1 – to an RAC officially-observed test. This took place at MIRA on March 8th, 1950. The test was not concerned with speed, as such, but in the course of it the turbine Rover attained more than 85 m.p.h. at a compressor-turbine speed of 35,000 r.p.m. and it accelerated from 0-60 m.p.h. in 14 seconds, smoothly and with no objectionable noise or other factors, although there was no silencer. The turbine “lit-up” at 10,000 r.p.m., and to attain idling speed took 13.2 seconds, the Rover moving off in a total of 16.6 seconds. The day after this convincing baptism the car was driven at speed on Silverstone circuit – it was a most enthralling open two-seater version of “Cyclops”-Rover 75, with two aeroscreens and decked quarters under which cover lived the mysterious turbine. Someone should make an external replica of it!
To Rover’s eternal credit, development work was continued and just over two years later the same car with the same standard chassis except for newly-adopted Girling disc brakes, was taken out to the Jabbeke motor race in Belgium to establish the very first gas-turbine class records. A new single-chamber turbine running up to 39,500 r.p.m. compressor speed and developing 230 b.h.p. on the test bench, had been installed. The final drive ratio was 17.745 to 1, in conjunction with 4.875 reduction gearing and a 3.64 to 1 back-axle ratio. The driver held the compressor speed to 37,500 r.p.m. and covered the two-way kilometre at a mean speed of 140.433 mph, and the two-way mile at a mean speed of 137.403 m.p.h. These were officially-observed World’s records. Next day, realising that the Rover T8 turbine was giving ample power, the car’s axle-ratio was raised to 3.275 to 1 and the aforesaid speeds were increased to an official 151.965 m.p.h. and to 151.196 m.p.h. respectively. Impressive!
If we gloss over gas-turbines developed about this time for commercial-vehicle installation, such as the Barr, White and Leach Contrax, and the first successful lorry of this type, the American 10-ton articulated Kenworth powered by a Boeing 502 gas-turbine, which was followed by a prototype French Laffly turbine-powered 10-tonner, these actual lorries appearing in 1950 and in 1951, respectively, we can pass to further gas-turbine car experiments and demonstrations.
Here I must digress backwards in order to commend the initiative of the British Automobile Racing Club, which in September 1946 had offered an award of not less than £1,000 for the first car with a non-reciprocating prime mover (of other than steam, electricity or direct-air propulsion) to win a 30-mile race at Goodwood at not less than 60 m.p.h. Joseph Lowrey, ever ingenious, had hoped to borrow and enter the Rover turbine record-car but this never happened and apparently no race would have been held for just a lone runner, anyway. (I should not have reminded you of this, perhaps, because all I have to do is to borrow a Mazda RX-7, persuade a few NSU Ro80 owners to join in, and I might have £1,000 in my pocket – except that Goodwood as a race-course is now closed. . . .)
The next gas-turbine car to appear seems to have been a Gregoire-Hotchkiss exhibited at the 1952 Paris Salon, powered by a 100 h.p. SOCEMA triple-combustion-chamber unit fed by a centrifugal compressor. This drove via a 5:1 reduction gear and a propeller shaft to a disc clutch, Cotal electro-magnetic gearbox and a Telma electro-magnetic brake, all behind the driving seat, in an assembly on the de Dion back axle.
By this time General Motors, Ford and Austin had shown interest. A Chrysler experimental project with a 370 h.p. turbine appeared in 1954, its kerosene-burning single-stage unit having a nozzle temperature of 815 deg. C and running modestly at around 13,000 r.p.m. and lighting-up at only 3,000 r .p .m., to idle at 8.000 r.p.m. The drive was to a de Dion back axle via a two-speed-and-reverse gearbox. This cigar-shaped job was run at the GM proving ground. Chrysler used a heat-exchanger and claimed a fuel consumption the equal of a piston-engine, and an ability to run on anything from gasolene to heavy oil. Their 32″ x 33″ x 28″ single-stage power turbine was in series with the compressor turbine, drove through a 2:1 gear, and saved 200 lb. when installed in a Chrysler Belvedere sports coupe, for which a reverse gear was added. I remember driving one of these turbine Chryslers on Surrey roads. Also in 1954, the Austin Motor Company put a 125 h.p. turbine with heat-exchanger into a Sheerline saloon, for experimental evaluation. It used a three-stage turbine driving a two-star compressor, then a separate power turbine. That year Fiat, not to be outdone, had shown a rather luridly styled and lined turbine coupe at the Turin Show. It had a rear-mounted two-stage compressor/two-stage turbine set up, producing some 200 b.h.p. at a compressor speed of 22,000 r.p.m. No gears were used apart from the down-step, so there was two-pedal control. The chassis had a de Dion back axle, a tubular frame, all-round independent suspension and was given a tunnel-tested body with tail tins. As there was no heat-exchanger fuel consumption was double that of a piston-engined car. The air intake was in the nose, the exhaust duct in the rear, pointed upwards as on the Rover. Turbine nozzle temperature was some 800 deg. C. This sleek Fiat was demonstrated at Turin Airport before the Show doing 135 m.p.h.
In 1955 – Jubilee Year – Austin demonstrated their Sheerline Turbine, TUR 1, before a large assembly of employees and guests on a disused airfield, of which our picture is a reminder, although it was still a closely-guarded secret, and Rover showed their civilised T3 turbine coupe at the Earls Court Show. In 1956 Renault entered the turbine arena. With a very well-streamlined, all-enveloping racing single-seater Etoile Filante, powered by a Turbomeca, built largely of duralumin and magnesium alloys and weighing 950 kg., this was really an experimental vehicle. I saw it do some demonstration laps at a Continental circuit before a Grand Prix and at the Bonneville Salt Flats it took the World’s gas-turbine record to 191.2 m.p.h. It is now in the Renault Museum in Paris.
The greatest breakthrough to date came in the years 1963 and 1964, at Le Mans, when the gas-turbine Rover-BRM ran in this classic race. As a formula to equate its power unit with a piston-engine could be agreed, it ran first as a demonstration, driven by Ginther and Graham Hill, who coped nobly with the new techniques demanded and not only averaged 93.2 m.p.h. for the 24 hours, but finished in 7th place, tying with an AC Cobra. In 1964 the Rover-BRM wasn’t sufficiently ready to give another such convincing demonstration before race-goers, but in 1965 it fully vindicated the delay. Now equipped with a heat-exchanger to reduce its thirst for paraffin, the car was driven by Graham Hill and Jackie Stewart as a normal Le Mans competitor. It finished the race in 10th place, was 3rd in its class, having averaged 98.88m.p.h. It was managed by Wilkie Wilkinson and used fuel at the rate of 13.52 m.p.g. (176 1/2 gallons of paraffin) for the 2,370.7 miles covered. It would have done even better, no doubt, had not the compressor developed trouble and the jet-pipe temperature overheated. As it was, this remarkable Rover-BRM did not need a tyre change, consumed only three pints of oil, and in ten pit-stops required only a change of back brake pads. If driving was no easy task, due primarily to turbine-lag when the throttle was closed, clearly no reliability problems remained.
Enough has been written to show that the gas-turbine car is no freak. So it is rather astonishing that it has yet to surface as a commercial proposition. The closest Mercedes-Benz., those talented engineers, have come to it publicly is with the Wankel-powered C-Ill. Although the Wankel rotary engine and the turbochargers have to some extent made the grade, the pure turbine has not. But that 1965 Le Mans performance by the Rover-BRM, aided by an American heat-exchanger (when, incidentally, the car was 9th in the Thermal Index contest and the first British car to finish the race) makes me proud to run a Solihull-engineered car.—W.B.