CHRYSLER CORPORATION
Press Information Service
Detroit 31 Michigan
TUlsa 3-4500
HIGHUGHTS OF GAS TURBINE ENGINE DEVELOPMENT PROGRAM
AT CHRYSLER CORPORATION
Chrysler Corporation -- the first major U.S. auto
manufacturer to be awarded prime contracts by the U.S. Government for missile development and production - - has
a long history of interest in the gas turbine engine.
Brief engineering surveys of gas turbine potentialities
for automotive use had been made prior to World War II. These studies showed that although the gas turbine engine
had strong possibilities of being an ideal automobile engine, neither materials nor techniques had advanced to
the point where the cost and time of research would be warranted.
Chrysler Corporation became directly involved, during
World War II, in the development of aircraft turbine engines and superchargers as part of its defense production
program.
Chrysler engineers resumed limited experimental work
on a laboratory auto gas turbine engine in 1945. Also at this time, because of the firm’s early interest in gas
turbine theory, Chrysler was awarded a research and development contract by the U.S. Navy to create a turboprop
engine for aircraft, This program - - although terminated in 1949, due to lack of military development funds in
the pre-Korean War period, -- resulted in the development of a turboprop engine which achieved fuel economy approaching
that of aircraft piston engines and resulted in new knowledge of the perplexing problems involved in translating
gas turbine theory Into practical application.
With this additional experience at hand, Chrysler
research scientists and engineers returned to their original objective -- the automotive gas turbine engine.
Chrysler’s first gas turbine engine was designed
primarily as a laboratory tool to check the performance of various components placed together as a power plant
and to help determine if a small gas turbine based on the regenerative principle would be practical in an automobile.
This engine, rated at 100 true brake horsepower,
was installed in a 1954 standard Plymouth passenger car, the first serious attempt by an American auto firm to
apply a gas turbine engine to an in-production automobile rather than to a special test-bed vehicle.
Later, the success of this first engine was graphically
demonstrated in a transcontinental test run from New York City to Los Angeles in March 1956, using a standard production
Plymouth as a turbine-powered vehicle. Relatively good fuel economy -- 13 to 14 miles per gallon -- was achieved
throughout the trip although this component test engine was not in any sense a developed power plant.
The New York City-Los Angeles run also marked the
first time the continent had been spanned by a turbine-powered passenger car and proved the first practical application
of the regenerative principle in operation over standard U.S. highways.
Through extensive experimentation and design modification,
Chrysler engineers gradually reduced the inherent problems of the gas turbine bit-by-bit. Basing their calculations
on performance results of the 1956 cross-country test run, they decided to enlarge the second engine, developed
in 1957, to get more power and to simplify some of the basic problems encountered in the smaller engine, it was
rated in the 200-horsepower range and in essence, because it was a larger engine, the second generation engine
was easier to work with. It became a more practical laboratory tool and, in the process, eliminated some of the
problems existent in its smaller brother.
To support laboratory findings, the second-generation
gas turbine engine was installed in a standard Plymouth passenger car for operation over a 576-mile highway test,
from Detroit to New York, in December of 1958. The engine achieved economy of 19.4 miles per gallon at a constant
speed of 37 miles per hour and on the return trip achieved 17.25 miles per gallon at an average speed of 52.5 miles
per hour, including stops, city traffic and highway driving.
Successful though it was, and a decided advance over
its predecessor, the second engine was larger than desired for practical passenger car use, Chrysler engineers
decided. So a decision was made to redesign the engine for a third time, making it smaller, incorporating the benefits
of the lessons learned from work on the previous engines.
The result of this design decision was the development
of the third generation of Chrysler gas turbine engines, the present Model CR2A which is a much more practical
device than its ancestors and is essentially intended for use in a passenger car.
Its most satisfying features, Chrysler engineers
say, have been its smaller size, reduced weight (about two-thirds that of a comparable piston engine), improved
economy and particularly its reduction of acceleration lag. (The first gas turbine engine had an acceleration lag
of seven seconds from idle to full-rated output; the second engine required three seconds to achieve maximum vehicle
acceleration; the third engine -- the present Model CR2A -- requires less than one and one-half seconds to accomplish
the same performance,)
The present gas turbine engine has a gas generator
speed of 20, 000 rpm when the engine is operating at idle. When the fuel (gas) pedal in the driver’s compartment
is depressed to accelerate the vehicle, that speed increases to 45,000 rpm within one and one-half seconds, which
is design speed for the engine.
It is this amazing speed-up of moving parts that
accounts for the smooth get away and acceleration rate of the turbine-powered car, Under such acceleration conditions,
the increase in movement is a smooth, steady one for the passenger and driver,
Under present conditions, the piston engine vehicle
might have a slight initial edge on acceleration but it is overtaken by its counterpart turbine-powered car in
a very short time. Within, a matter of seconds, the piston-powered vehicle cannot hope to equal the performance
of the same type of gas turbine-powered vehicle.
Such performance gains result from continued improvement
of compressor and turbine design and higher torque availability, Chrysler engineers point out.
Some of the turbine engine problems solved by Chrysler
research scientists and development engineers since 1945 are astonishing, to say the least.
From the burner through the turbines, there is a
drop in pressure of the gases to atmospheric pressure, but the gases retain large amounts of heat, which would
be wasted if merely allowed to escape through the exhaust pipe. So a device for salvaging this heat is placed in
the path of the out-rushing gases. This component is the famous Chrysler originated regenerator, a form of heat
exchanger. It recovers heat from the hot exhaust gases and transfers this energy to the high-pressure air coming
from the compressor. This lightens the burner’s job of raising the gas temperature for entry to the turbines. The
result is conservation of fuel as well as lower exhaust temperatures.
The key to outstanding performance in the Chrysler
turbine engine Is a variable second-stage nozzle mechanism. This device allows continuous automatic variation of
the nozzle blades with gas generator and vehicle speed, so that the gas flow is directed to the power turbine wheel
blades at an angle of attack optimum over the entire operating range for the achievement of economy, acceleration,
or braking.
Reversing the nozzles makes it possible to obtain
greater engine braking than from a piston engine with a torque converter drive. The braking torque is appreciable
at high power turbine speeds, and a small reverse torque can actually be obtained with the power turbine stalled.
Early in the gas turbine engine development program,
Chrysler project engineers realized they could not use large quantities of high-cost alloys if their turbine engines
were to be mass-produced. For one thing, the free-world supply of some of these alloys would not be sufficient
to meet the requirements of even a small-scale passenger car gas turbine production program.
Therefore, they set out to do the impossible: to
develop a low-cost, low- strategic alloy content material for turbine buckets which would have the high temperature
strength, stress rupture, and creep characteristics of a much used and well-known cobalt-base alloy.
Chrysler metallurgists developed such metals, one
of which has a stress- to-rupture value at high temperature, of 30,000 pounds per square inch and the other equal
to 27,000 pounds per square inch under the same conditions.
Another alloy program by Chrysler metallurgists proved
highly successful and led to the development of an oxidation-resistant material. This material is now used for
the gas turbine engine’s burner liner and in other internal parts.
In the all-important field of fabrication and joining
metals, Chrysler had to develop processes, which would lend themselves to production as well as be reliable.
They found, for instance, that they could either
cast a turbine wheel ring together with alt its blades and weld to it a combined hub and disc of lower alloy, or
cast the entire disc with its blades as a single unit. Both processes have proven feasible for high-production
manufacturing at a modest cost.
As far as Chrysler’s production experts are concerned,
they have to create a textbook on the machines and techniques that have to be devised to build turbine engines
economically. Otherwise, no major technological or material problems now remain which could render production of
the gas turbine engine for passenger car use unlikely. Progress in turbine engine development in the past two years
has far exceeded expectations and the rate of improvement is moving steadily upward with each refinement of the
component engine.
Further improvements in fuel economy, reliability,
performance, simplicity, cost, materials developments and weight (as well, as reduction in size) are inevitable.
Theoretically, a gas turbine engine could run forever
because of It’s simplicity and because it is a frictionless machine. Air and heat (fuel) do the work. Because the
turbine is basically the most simple of man’s power machines (a windmill or waterwheel is a turbine), it has few
working parts.
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