Almost from the moment the first horseless carriage took to the road, automotive developers have sought alternatives to the reciprocating internal combustion engine that powers our cars even to this day - and, quite likely, for the foreseeable future. Despite its staying power, however, there have been a number of challenges to this time-honoured technology.
A notable advance of the late 1950s was Felix Wankel's work on a rotary engine that today bears his name. The Japanese car maker, Mazda embraced the Wankel engine concept with enthusiasm and was responsible for its refinement and some major engineering achievements, including a hydrogen fuelled version. And in 2008, the company celebrated the 40th anniversary of its first two-stage, Wankel engine-powered production car by introducing a limited edition of the car that put Wankel on the map - the iconic RX-8.
Somewhat earlier– during the Second World War, in fact – the UK’s Rover Car Company was already working to develop a viable piston engine alternative – nothing less than an automotive gas turbine engine. Indeed, Rover’s early work on gas turbines was later transferred to Rolls-Royce, and the rest, as they say, is history.
Rover did persevere, however, and in 1950 unveiled a gas turbine powered experimental prototype car, the Jet 1, which managed to reach a speed of 90mph at an engine speed of 50,000rpm - albeit with a rather disappointing fuel consumption of five, at best seven, miles to the gallon. Jet 1 never advanced beyond the prototype stage and this fine example of British post-war engineering aspiration can now be viewed in all its splendour in the great ground floor exhibition room of the London Science Museum.
Meanwhile, on the other side of the pond, jet propelled automobile fever was also running its course. In the spring of 1954, Chrysler Corporation disclosed the development and successful road testing of a 1954 production model Plymouth sports coupe powered by a gas turbine engine. Later that summer, the car was demonstrated at Chrysler’s proving grounds in Michigan and marked the first attempt by an American car maker to incorporate a gas turbine engine in a production vehicle.
Although it was barely out of Chrysler’s engineering laboratory, the 100hp engine was nothing short of a marvel for its time, addressing the two hitherto insurmountable technical barriers to vehicular gas turbines - high fuel consumption and the problem of extremely hot exhaust gases.
The breakthrough came in the form of a novel heat exchanger, or ‘regenerator’ as Chrysler dubbed it. This extracted heat from the hot exhaust gases, transferring the recovered energy to the air intake and thus raising the gas temperature prior to ignition. This not only conserved fuel but also reduced exhaust temperatures from about 650oC at full power to less than 260oC. At idle, the exhaust temperature was just 76oC, and by the time the gases passed through the exhaust ducts to the atmosphere, the temperature was reduced even further.
But financial problems dictated the course of Chrysler’s automotive gas turbine ambitions and the constraints of a government rescue package put paid to ‘risky’ development work. Chrysler subsequently abandoned its advanced work in this area by around the mid-1970s; further development effort by the industry passed into obscurity – until quite recently, that is.
Nowadays, of course, the aim of engine development is to reduce emissions and achieve super fuel efficiency. The electric motor now seems to be the rotary power source of choice. So, while we might be forgiven for believing that the ambitious jet-propelled automotive era is long past, there appears to be life in it yet – though in a more ‘hybrid’ guise to suit the fashion of the age.
A consortium led by micro gas turbine company Bladon Jets last week secured investment from the Technology Strategy Board to develop an ‘Ultra Lightweight Range Extender’ (ULRE) for next generation electric vehicles. The objective of the consortium, which includes luxury car maker Jaguar Land Rover and the Emerson Group switched reluctance motor specialist SR Drives, is to produce a commercially viable and environmentally friendly gas turbine generator designed specifically for automotive applications.
The ULRE design seeks to couple a Bladon Jets axial flow gas turbine engine with a high speed generator, based on SR Drives’ proprietary switched reluctance technology. The design phase will be overseen – appropriately enough - by Jaguar Land Rover, given the erstwhile Rover Car Company’s involvement in the similarly inspired venture of more than 60 years earlier.
Bladon Jets’ chairman Paul Barrett looks forward to seeing his company’s micro gas turbine engine technology play a significant role in what he believes will herald a ‘renaissance’ of the British automotive industry. In one sense, ‘renaissance’ is the mot juste, given the relative venerability of the gas turbine and the switched reluctance principle. There may be nothing new under the sun but modern versions of these technologies in combination suggest interesting times ahead for automotive power train development.
Les Hunt, Editor
PS - it seems I was rather dismissive of Rover's efforts regarding the development of its automotive gas turbine technology. DPA newsletter reader, Colin Downey has filled in the missing detail with this fascinating acount of what followed after 1950.....
A. 1950.
JET 1. World's first jet car Inboard rear engine, suspension and brakes etc. standard P4.
Compressor turbine 40,000 rpm light-up at 3,000rpm
Power turbine max 26,000rpm idle 13,000rpm
Max bhp 100.
Test speed 85mph. Max mpg 6.
B. 1952.
Updated JET 1. Inboard rear engine.
4-wheel prototype Girling disc brakes.
Turbine specs as above
Max bhp. 230
Test speed 152mph (world record). Max mpg 6.
C. 1952.
T(for turbine car) 2A - like T2, best forgotten. Outboard rear engine.
The Rover T3
D. 1956.
T3. First car specifically designed around gas turbine engine, by Spencer King with Gordon Bashford and Peter Wilks.
Inboard rear engine (2S100 - 2 shaft, lOOhp)
4-wheel drive, fixed diff. Sheet steel frame, glassfibre body (David Bache). DeDion rear suspension, back-angled front forks, 4-wheel inboard Dunlop disc brakes - Most of these innovations were to be used on the P6, seven years later!
Compressor turbine 52,000rpm, light-up 15,000rpm
Max bhp 110
Max mpg 13 (with heat exchanger).
E.1961.
T4. 2 years before production P6. Basic P6 unit body shell with modified nose. Front engine, front wheel drive.
Rear suspension, swing axles with coil springs.
Max bhp 140. Acceleration 0-60mph,8 seconds.
Max mpg 20 (with heat exchanger)
The Rover T4
F. 1963
The Rover-BRM (00) had been driven at LeMans by Graham Hill and Richie Ginther at an average of 108mph (and 7mpg) which would have made it 8th overall, but it was not officially competing, hence the 00 number.
The Rover BRM (pictured above)
G. 1964
Rover-BRM, rebodied by David Bache and Bill Towns, was damaged in transit to LeMans, and did not compete that year.
H. 1965
Increased air-intakes and extra driving lamps, driven at LeMans by Graham Hill and newcomer Jackie Stewart, was 10th overall at 99mph (13.5mpg) in spite of engine damage.
How did these cars behave? Graham Robson describes his first (and only) drive in T4...
"Starting drill is simple but drawn out - turning the key actuates the special Lucas starter motor which winds away for several seconds. A faint, distant whine rises in pitch and intensity before light-up occurs and the engine settles down to 'idle' at 35,000rpm. This is enough to cause the car to creep along the road if the brakes are not applied, as there is about 4bhp residual at idle. To get moving engage forward gear and depress 'loud pedal' - after a jet lag of about 3 seconds, the engine speed rises rapidly to 50,000rpm and the car whooshes off up the road leaving engine noise behind (although this is quite acceptable to passers-by). 60mph is reached in 8 secs (a la 3500S) with very civilized handling.
T3 and T4 were the magnificent swan songs of Rover's gas-turbine cars - whatever happens in the future, Rover were the first and most successful (T4's achievements have never been matched). T3 and T4 happily survive in running condition in the British Leyland Collection, while JET 1 is honorably retired in the Kensington Science Museum.
I am most grateful to Colin for putting the record straight!