Moss’s early experiments failed; his machine guzzled too
much fuel and produced too little power. But his patent
and his revolutionary compressor design were sound and
found many applications: from supplying air to blast
furnaces to powering pneumatic tube systems. He didn’t
know it, but he had pointed the way to the jet engine
before the Wright Brothers even took off.
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In November 1917 – at the peak of World War I
- GE President E.W. Rice received a note from
National Advisory Committee for Aeronautics, the
predecessor of NASA, asking about Moss’s radial
compressor. WWI was the first conflict that
involved planes and the agency wanted Moss to
improve the performance of the
Liberty
aircraft engine. The engine was rated 354
horsepower at sea level, but its output dropped
by half in thin air at high altitudes. Moss
(right in the picure above) believed that he
could use his compressor to squeeze the air
before it enters the engine, making it denser
and recovering the engine’s lost power.
Using a mechanical device to fill the cylinders
of a piston engine with more air than it would
typically ingest is called supercharging. Moss
designed a turbosupercharger that used the hot
exhaust coming from the
Liberty
engine to spin his radial turbine and squeeze
the air coming inside the engine. In 1918, when
he tested the design at 14,000 feet on top of Pike’s Peak, Colo.
The engine delivered 352 horsepower, essentially
its rated sea level output, and GE entered the
aviation business.
The first Le Pere biplane powered by a
turbosupercharged Liberty engine took off on
July 12, 1919. “The General Electric
superchargers thus far constructed have been
designed to give sea-level absolute pressure at
an altitude of 18,000 feet, which involves a
compressor that doubles the absolute pressure of
the air,” Moss wrote.
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In 1937, on the eve of World War II, GE received
a large order from the Army Air Corps to build
turbosuperchargers for Boeing B-17 and
Consolidated B-24 bombers, P-38 fighter planes,
Republic P-47 Thunderbolts, and other planes. GE
opened a dedicated Supercharger Department at Lynn, Mass.
In 1939, Moss proposed to build one of the first
turboprop engines. Trained as a gas turbine
engineer, he later joined the National Aviation
Hall of Fame.
But GE’s aviation business was just getting
started. In 1941, the
U.S. government asked GE to
bring to production one of the first jet engines
developed in England by Sir
Frank Whittle. (He was knighted for his feat.) A
group of GE engineers called the Hush Hush Boys
designed new parts for the engine, redesigned
others, tested it and delivered a top-secret
working prototype called I-A. On October 1,
1942, the first American jet plane, the
Bell XP-59A, took off from
Lake Muroc in
California
for a short flight. The jet age in the U.S. had begun.
The demand for the first jet engines, called J33
and J35, was so high that GE had a hard a time
meeting production numbers and the Army
outsourced manufacturing to General Motors and
Allison.
GE decided to double down and invest in more jet
engine research. The J33 and J35 engines used a
radial - also called centrifugal - turbine to
compress air, similar to the design that Moss
developed for his turbosuperchargers. But GE
engineers started working on an engine with an
axial turbine that pushed air through the engine
along its axis. (All jet engines use this design
today.) The result was the J47 jet engine that
powered everything from fighter jets like the
F-86 Sabre to the giant Convair B-36 strategic
bombers. GE made 35,000 J47 engines, making it
the most produced jet engine in history.
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The J47 also found several off-label
applications. The Spirit of America jet car used
one, and a pair of them powered what is still
the world’s fastest jet-propelled train. They
also served on the railroad as heavy-duty snow
blowers.
In 1948, GE hired German war refugee and
aviation pioneer Gerhard Neumann, who quickly
went to work on improving the jet engine. He
came up with a revolutionary innovation called
the variable stator. It allowed pilots to change
the pressure inside the turbine and make planes
routinely fly faster than the speed of sound.
When GE started testing the first jet engine
with Neumann’s variable stator, the J79 (see
below), engineers thought that their instruments
were malfunctioning because of the amount of
power it produced. In the 1960s, a GE-powered
XB-70 Valkyrie aircraft was flying in excess of
Mach 3, three times the speed of sound.
The improved performance made the aviation
engineers realize that their variable vanes and
other design innovations could also make power
plants more efficient. Converting the engines
for land use wasn’t difficult. In 1959, they
turned a T58 helicopter engine into a turbine
that produced 1,000 horsepower and could be used
for generating electricity on land and on boats.
A similar machine built around the J79 jet
generated 15,000 horsepower. In Cincinnati, where GE Aviation moved from Lynn in teh 1950s, the local utility built a
ring of 10 J79 jet engines to power a big
electricity generator.
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The first major application of such turbines,
which GE calls “aeroderivatives” because of
their aviation heritage, was as power plants for
the Navy’s 76,000-ton Spruance-class destroyers.
The turbines now also power the world’s fastest
passenger ship, Francisco. It can carry 1,000
passengers, 150 cars and travel at 58 knots.
Today, there are thousands of
aeroderivatives working all over the world. Most
recently, they have been helping Egypt’s growing
economy slake its thirst for electricity.
At the same time, GE Aviation is working on
the next-generation jet engine called
ADVENT, or Adaptive Versatile Engine
Technology (above). “To put it simply, the
adaptive cycle engine is a new architecture
that takes the best of a commercial engine
and combines it with the best of a fighter
engine,” says Jed Cox, who leads the ADVENT
project for the U.S. Air Force Research Lab.
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