Friday 22nd January 1954
General Montors demonstrated the XP21 Firebird – the first gas turbine car unveiled in the United States (Chrysler’s first turbine-powered car debuted to the public a couple months later, in March 1954) – in New York City. Power came from a GM-designed GT-302 Whirlfire Turbo-Power gas turbine engine, which utilized a two-stage design incorporating both a gasifier section and a power section. Unlike a jet airplane, which uses thrust for propulsion, the Firebird concepts relied upon this thrust to drive a power turbine, which in turn was linked to a transmission that powered the driven rear wheels. Output was rated at an impressive 370 horsepower, once the gasifier turbine spooled to 26,000 RPM and the power turbine was spinning at a more relaxed 13,000 RPM. Like a conventional piston engine, idle speed of the GT-302 engine was considerably lower, but in this case that’s a relative term, as the gasifier turbine still spun at 8,000 RPM.
From the beginning, the Firebird I was all about performance, and early estimates put the car’s theoretical top speed at somewhere above 200 MPH. Plans were made for the car to be tested at the Indianapolis Motor Speedway by noted racing driver Mauri Rose, but before this could happen, Charles McCuen, then a vice president in charge of GM’s Research Laboratories, crashed the prototype at the Milford Proving Ground. Unfamiliar with the acceleration of gas-turbine vehicles (and their lack of engine braking), McCuen found himself unable to slow for a corner, and the low-slung Firebird concept passed beneath the safety barrier on the outside of the banked turn. The executive was seriously injured in the crash, though he would later recover and return to GM. A new body was produced for the Firebird, which was eventually repaired for testing by Rose. Shaken by the car’s first crash (and likely out of additional spare parts), GM mandated that there would be no high-speed testing, a fact which surely frustrated Rose.
As with any pioneering idea, the Firebird I had its share of problems. Its output proved to be too much for the two-speed transmission, and project leader Emmett Conklin reportedly experienced wheelspin when shifting into second gear (an attention-getting prospect at 100 MPH). The car was particularly noisy, guzzled fuel, and produced exhaust temperatures of over 1,000 degrees Fahrenheit. As a testbed for GM’s gas turbine engine technology, however, the Firebird accomplished its mission in proving that such an engine could be adapted for automotive use; optimization was another matter entirely.
In 1956, GM introduced its second Firebird concept car, known internally as the XP-43 and constructed under S.O. 2683. Unlike the performance-oriented original, the Firebird II was built to demonstrate what the family car of the future might look like, assuming, of course, it relied on a gas turbine engine for propulsion. Now adapted for four passengers with an oversize bubble roof, the Firebird II looked more like an automobile than a fighter aircraft, but the high-tech features envisioned by GM were straight out of the space age.
Designed for “the highway of the future,” the Firebird II featured sensors that allowed it to follow an electric wire embedded in the roadway, overseen by a network of Autoway attendants. Though that particular future didn’t evolve quite the way GM had envisioned, the Firebird II did show off a remarkable amount of technology, including a self-leveling air/oil suspension; “anti-skid” brakes; disc brakes with a floating rotor design; a rear-facing camera system for improved visibility; a luggage platform that rose from the trunk, simplifying the loading and unloading process and a titanium skin (on the display car only) that offered the strength of steel with the weight of aluminum. Its most innovative feature, however, was a regenerative system that cooled the exhaust to reduce danger while pre-heating air entering the compressor for improved fuel economy. The ingenious system quieted the car as well, and contemporary reports claimed that the car’s GT-304 Whirlfire engine (reduced in output to a more manageable 200 horsepower) was now nearly as quiet and nearly as fuel efficient as a conventional piston engine.
The final Firebird model would be the Firebird III, constructed in 1958 as XP-73 under S.O. 90238. If the original Firebird was about performance and the second Firebird was about practicality, the final Firebird was Harley Earl’s best effort to bring these two worlds together. Perhaps the most conventionally styled Firebird of all (except, perhaps, for its seven fins designed to add stability), the final version of the series boasted a twin bubble cockpit design that was “flown” on the road via a “Unicontrol” joystick instead of conventional controls. Accelerating required the driver to push the stick forward, braking required it to be moved to the rear, and a change in direction was accomplished by moving the stick to the left or to the right. The Firebird III earns the distinction of being the first electronically controlled car, and it also relied on primitive computer systems to temper driver input to avoid a loss of control.
Power came from a further evolved gas turbine engine, and its GT-305 Whirlfire engine now produced a balanced 225 horsepower. The engine was also 25 percent lighter than its predecessors, while producing a further 25 percent improvement in fuel economy. To power systems unrelated to propulsion like power steering, brake pumps, wing-mounted air brakes (a feature common to all Firebird models), the self-leveling air/oil suspension and the air conditioning compressor, the Firebird III utilized a separate gasoline-powered 10hp twin-cylinder engine, designed for fuel-efficiency.
Like the Firebird II, the Firebird III featured sensors for Autoguide routing and Cruisecontrol that allowed for autonomous operation. First shown at the 1958 Motorama, GM dusted off the Firebird III for exhibition at its final Motorama event in 1961. Today, all three cars are part of the collection at the GM Heritage Center, and they’re occasionally displayed at car shows and concours d’elegance events from coast to coast.
Though the future didn’t happen quite as GM’s engineers imagined, today the role of the Autoway attendant is in part filled by OnStar. Anti-lock brakes and electronic stability control are now mandated in new cars, and fly-by-wire throttles have long replaced mechanical connections between accelerator and throttle. Global Positioning Systems allow drivers to route themselves from point to point via a choice of roads, and even display roadside necessities in advance of each and every exit. Communication for the car isn’t a challenge these days, either, as virtually everyone of kindergarten age and above owns a cell phone, the bulk of which can be paired with modern automobiles via Bluetooth.
Gas turbine engines never saw production, and GM’s Firebird concepts didn’t get all the details of the future correct, but it’s hard not to be impressed with the amount of features the concepts did predict, decades before they became commonplace.