Whistling in the dark
Gas turbine racers were hot news for a few experimental years. Gordon Cruickshank explains
Gas turbines in cars just don't work. If they did we'd all be running one today. But over three decades, from the 1950s on, engineers on both sides of the Atlantic put immense resources into trying to marry an aircraft engine to a road vehicle. And turbine cars twice came within a gnat's crochet of pulling off victory in the Indianapolis 500. So what finally wore them down and ended years of development?
First, why go to all this effort? Easy: turbines are simple. Think of an exhaust turbocharger. Hot exhaust gas spins the turbine on one end of the shaft; the turbine fixed on the other end hauls in air, compresses it and forces it into the engine, which burns it and produces hot gas to continue the cycle. Now imagine short-circuiting the engine completely and feeding the incoming air straight to the exhaust turbine — only you inject some fuel and light it before it gets there. Now you have huge amounts of hot gases gushing through, about nine times more than you need to spin the compressor, in fact. Install a third, separate set of turbine blades for all those hot gases to spin, connect that to the wheels, and you've just made a gas turbine vehicle. It's almost a supercharger without the engine; you've simply dumped all those heavy parts like cranks and pistons.
That is why, as the technology emerged after 'WWII, engineers became so keen on turbines. One fifth of the moving parts of a piston engine. Nothing sliding back and forth; the parts are lightly stressed, so the unit is light. There are no cranks, pistons or valves, so there's minimal friction and, apart from its high-speed bearings, no need for an oil system. Or a cooling system — the air flowing through it keeps it stable. There's virtually no vibration; it isn't fussy about fuel. Any flammable liquid will power it, from avgas to after-shave — including diesel. It runs very lean, so it emits almost no noxious CO gas. It needs no warming up; you can't over-rev it, and it needs little maintenance. Above all, it's compact: today you can even buy a motorcycle powered by a 300hp gas turbine.
Even better, because that third turbine isn't mechanically connected to the first two, you don't need a clutch: the hot gas functions like the torque converter in an automatic, allowing slip between the two parts. Your turbine can idle or rev up with the car stationary, or can spin at its optimum torque revs no matter what speed the car is doing — ergo, no gearbox, just a fixed geartrain to reduce the turbine's 50-60,000rpm working regime to useable revs.
Of course, nothing's perfect. All those tiny turbine blades demand precision engineering and high temperature resistance. Throttle response is slow, which affects driveability and doesn't make for rapid racing starts. Most of all, a gas turbine swallows a lot of fuel. This was the biggest problem facing the Rover and Chrysler engineers who were the first to try to make it work
Rover became involved in 1939 when the government asked it to develop Frank Whittle's new idea for a jet engine. The project passed to Rolls-Royce in 1942, but the expertise remained, and Rover began a road car project immediately after the war ended. A P4-based car, JET 1, surfaced in 1950; two years later it was uprated from 100 to 230bhp and set a turbine car record of 152mph. The trouble was that it was doing about 6mpg. Consumption was radically improved by fitting rotating heat exchangers to absorb heat from the exhaust and release it to the intake air; this both halved fuel thirst and cooled the exhaust gases. (Contrary to popular opinion, turbine exhaust can be cooler than from a piston engine.) Rover was convinced it could work on the road, but it never happened: build cost and fuel thirst were just too steep.
But to prove that its technology worked, Rover decided to hit the track. Teaming up with BRM, Rover built a lumpy-looking mid-engined device and entered it for the 1963 Le Mans 24 Hours. Running as car 00 — there was no equivalence formula to allow it to compete for prizes — it performed respectably (if 7mpg can be respectable) with Graham Hill and Richie Ginther aboard. Had it been a formal entry it would have finished seventh. Rover took the revised car back to Le Mans for '64, but it was damaged in transit and didn't run. For '65, however, there was a new deal: a handsome new shape and an official entry. This time Jackie Stewart joined Hill, finishing 10th. The rewards just didn't merit the effort, and Rover called a halt. Hill, though, remained an enthusiast and would race 'jet cars' again.
In the USA, Chrysler bore the turbine torch through the 1950s and '60s, putting a succession of prototypes on the road from '54, and even giving 50 turbine cars to guinea-pig drivers. Using heat exchangers Chrysler dragged the fuel consumption close to piston cars, and also tackled another turbine drawback — lack of engine braking—with a clever variable nozzle system which also improved throttle response. It still wasn't enough; those 50 turbines of '63 remain the nearest thing to a turbine production run.
Record cars don't have such exacting needs, and two European manufacturers used turbines to set records in the Fifties.
In France, the shapely SOCEMA-Grégoire turbine coupe wowed the press at the 1952 Paris Show, but was little more than a PR exercise. Four years later Renault revealed its Etoile Filante (Flying Star). A pure record car, this packed a Turbomeca aircraft engine of 270bhp in a smooth centre-seat machine, which went to Salt Lake, Utah and took four world records at up to 192mph. In 1954 Fiat unveiled La Turbina, a Dan Dare body on an 8V chassis with a 190bhp turbine in the back. Unusually, Fiat routed the exhaust straight out of the tail, hoping for extra thrust; despite the common misnomer 'jet car', a turbine car drives purely through gears to the wheels. There was frankly little innovation in either machine and no pretence at future production; instead they showed that an existing aero engine was a simple route to power. From here on, all turbine competition cars did that.
Turbines work best at fairly steady revs — which is why they're ideal for aircraft. But there is one branch of racing where engine speeds hardly vary — oval racing. Specifically, Indianapolis. And that's where the gas turbine did, finally, almost come good.
First out of the blocks was John Zink, a regular Indy entrant, who in 1962 put a turbine in one of his Trackburner Specials. It failed to qualify, and Zink later crashed it on his Oklahoma ranch. Four years later the Jack Adams team inserted a 1250bhp General Electric turbine in a Demler roadster chassis. Fearing its power-to-grip ratio, USAC banned it before it even had a chance to qualify.
Then in 1967 Andy Granatelli stepped up. Speed record veteran, successful team manager and a PR ace, Granatelli reckoned a turbine could upset the ‘Indianapplecart’. At the time there was no equivalency formula between piston and turbine engines, so there would be no power limit on a turbine. With very high power outputs you need to be thinking of four-wheel drive to cope, and Granatelli had experience with his 4WD V8 Novi Ferguson Indy machines. He handed a Pratt & Whitney ST6B-62 engine to Ken Wallis, a self-styled engineer in the Paxton division of Granatelli's STP company who had been consultant on the Novis, and gave him free rein. The aim was to ready the car for '66, but Wallis was not good on schedules; in fact the Paxton STP was completed by Granatelli's team.
Granatelli had theorised earlier about putting the engine alongside the driver, and this suited the long gas turbine. Wallis put pilot and engine either side of a central backbone, with the exhaust firing upwards out of a vent by the driver's car. The turbine (red-lined at 57,500rpm) drove through multiple reduction gearing to a Ferguson 4WD system, though at a claimed 550bhp and a more probable 480 'Silent Sam' actually had less power than its conventional rivals.
Alongside the whistling aero engine Granatelli put Indy hero Parnelli Jones, who proceeded to qualify sixth and then lead most of the race. At last the turbine evangelists were proving their faith. Except that, with seven miles to go, a gearbox bearing failed. A five-buck part, nothing to do with the exotic power source... Jones later attributed his performance not so much to his power unit but to 4WD, which allowed him to pick any line around traffic. But some people had been impressed — Colin Chapman, for one, whose fertile brain began to scheme what became the Lotus 56. It was a sounder design than the Paxton, and he quickly forged a link with Granatelli.
Ken Wallis, as a result, went to Carroll Shelby, glowing from a Le Mans win, and persuaded him to build a team of turbine contenders for 1968. Goodyear provided the cash, and Shelby signed Denny Hulme and Bruce McLaren. The cars looked like wheeled spacecraft, again with engine alongside driver, but they were weighty and the backbone chassis flexed: they weren't nearly fast enough. McLaren described one after testing as being "like a cross between a Sherman tank and a Formula Ford". And they weren't legal. To even the field, USAC had now throttled the intake area for turbines, which crippled the big GE T68 aero-engine; unknown to Shelby, Wallis had 'adjusted' things to restore intake area, and power. When Shelby discovered this, just before scrutineering, he had to get out smartish; he withdrew his entry, citing safety concerns.
What Shelby didn't reveal was that there was a second project — an astonishing turbine Can-Am car. Unhampered by power restrictions, this would have a central T68 unit with the full 1100-plus bhp, torque-adjustable hydrostatic drive to hydraulic motors in all four wheels, and traction warning systems, all enclosed in a coupe body with lay-back driving position. On hold during the Indy project, this technofeast died with the oval racer, by which time Wallis had moved on, to design a steam-powered Indy racer...
But a team of turbine cars did contest Indy in 1968. Granatelli and Chapman teamed up to field the Lotus 56— a scarlet wedge with a chimney behind the driver's head. It was compact and logical, integrating Ferguson 4WD in a symmetrical, low-drag layout. Chapman achieved this by reversing the turbine, which inhaled from the tail and drove from the front end (behind the driver) via a Morse chain to the centre diff, with propshafts running fore and aft. Though the restrictions limited power to around 400bhp, well down on the field, Joe Leonard's 56 took pole at a record 171.599mph, with Graham Hill just behind. Though Hill crashed after a suspension breakage, Leonard was leading with about 10 laps to go when the yellow flags came out; forced to run slowly, a small drive component for the fuel pump overheated and failed. Leonard and Art Pollard in the third car both rolled to a halt. The wonder power source had flamed out again.
Full of conviction, Granatelli ran the 56 in road races in 1968 — they were barely competitive, until USAC rule changes effectively hobbled turbines forever. Formula One, though, allowed for greater power, so Chapman revised the car into the 56B for 1971. A series of failures and crashes obscured its potential, though in the rain-lashed Dutch GP Dave Walker was lapping faster than anyone else. But when he spun at Tarzan a potential win went up in smoke. So did Chapman. By the time the 56B turned in its one good result — second in an F5000 race at Hockenheim piloted by Emerson Fittipaldi — Chapman had lost interest and abandoned his proposed, much lighter 2WD car. The 56B remains the sole turbine machine to contest a grand prix.
Turbines popped up again at Indy, though, in 1969, when Jack Adams financed the Wynn's Storm Special, a Thunderbirds-style device like a grounded jet fighter with an Allison helicopter turbine in the front, driving all four wheels. Ak Miller drove, but failed to qualify. A year after, the Adams team installed the Allison in a Gerhardt chassis, which Leon 'Jigger' Sirois still couldn't qualify at Indy. Rick Muther tried again in '71, unsuccessfully, but did take an eighth in a USAC race at Trenton. Sirois remained a believer longest, racing a turbine dirt car into '72.
Oddly, while oval racing seems the best match for turbine characteristics, it was in Group Six sportscars that a kerosene-burner left the biggest vapour trail. Conceived by Philadelphia-based racer and engineer Ray Heppenstall, the Howmet TX project pre-dated the STP Paxton, though it didn't compete until '68. Heppenstall convinced the Howmet engineering combine that racing was good PR, but remained the mechanical brains.
He commissioned race car maker McKee to adapt an existing chassis to a Continental helicopter turbine, driving the rear wheels. The unit equated to 2960cc, and gave 235bhp with a truckload of torque, so there was no gearbox, just drop gears allowing ratio changes for different circuits. An electric motor provided the compulsory reverse gear. Otherwise the muscular TX was fairly conventional — barring the roof airscoop and the triple outlets firing a fierce heat shimmer above the tail.
Heppenstall's biggest trick was to cut throttle lag with a wastegate system; the engine spent more time at full revs, the gas flow being diverted to or away from the power turbo via the throttle pedal. It made the TX more driveable — but twice it stuck on high power, causing crashes in the Daytona 24 Hours and the BOAC 500 at Brands Hatch. But the two cars generally qualified well; at the Guards Cup at Oulton Park Hugh Dibley was secondfastest, and was lying fourth when the starter failed during a pitstop. The near-misses finally became a quartet of clean victories in a summer of US road races where, by winning the Heart of Dixie, Heppenstall became the first driver to win a race in a turbine car.
Two more FIA events remained. Howmets finished third and 12th in the Watkins Glen Six Hours (the only FIA sportscar points for a turbine), and then in September the team set off to Le Mans; the 24-hour classic had been postponed from June due to les événements the student riots of 1968. With proven success behind them, things looked good; but they began to go wrong from the start. Chassis No 1
(Dibley/Bob Tullius) broke a wheelbearing after two hours and fell so far back it was disqualified. No2 lost power early on, but struggled on until night, when Dick Thompson rolled at Indianapolis. That name was never lucky for turbine cars... By '69 Howmet had been bought over, and racing was canned.
Turbines are now banned in F1 and Indy racing, while among record machines true jet cars such as ThrustS SC have overshadowed turbine LSR devices like Donald Campbell's Bluebird CN7 and Don Vesco's Turbinator, current holder of the wheel-driven record at 458mph. Road car research continues, but with the urge to develop non-petroleum fuelled vehicles, turbines are on the back-burner.
But that hasn't stopped Project 1221. This Italian combine is working on a 1500bhp, 270mph supercar with a mid-mounted turbine, and hints that Le Mans might be on the schedule. Sounds unlikely? Project 1221's chief engineer is Ferrari legend Mauro Forghieri...
Our thanks to Karl Ludvigsen for his help with this feature