29-12-2012, 06:07 PM
A NASA Guide to Engines
A NASA Guide to Engines.pdf (Size: 4.62 MB / Downloads: 109)
HISTORY OF PROPULSION FOR AVIATION
Throughout man’s history there has been a constant
need for power to move. Whether to hunt for
food, to escape predators or enemies, to plow a field,
to take goods to trade, to go to war; there has always
been a need to get from one place to another.
ANIMAL POWER
Initially the only power available was your own
muscles or the muscles of some beast of burden. One
could go faster by riding a horse. More power could
be had by using teams of horses or oxen or hundreds
or even thousands of people, but there were certainly
limitations as to what could be done and how fast it
could be done.
WATER AND WIND
Water travel allowed for more speed and greater
loads, but one had to either row, sail, or go with the
current. Men did learn how to sail against the wind, but
the wind does not always blow. They built canals to go
where they wanted, but speed was a limitation.
STEAM ENGINES
The first steam engine was called an aeolipile
(“wind ball”) and was invented by a Greek, Hero of
Alexandria, in the 1st century AD. Steam entered a ball
and exited from one of two bent pipes. This caused the
ball to spin, but it was only used as a toy. The first steam
device to do actual work wasn’t invented until 1698: An
engine developed by Thomas Savery in England was
used to pump water out of flooded mines. Refinements
to the engine were made by Thomas Newcomen in
1712 and James Watt in 1769.
INTERNAL COMBUSTION PISTON ENGINES
During the period of time from 1860 to 1900 a
number of creative people developed a variety of
reciprocation piston engines that burned fuel within
cylinders. The first patent for such an engine was by
Samuel Morey of the United States in 1826. In 1858,
Belgium-born Jean Lenoir patented a double-acting
piston engine that ran on coal gas. He applied it to a
three-wheeled vehicle that he drove 50 miles in 1862.
The French inventor Alphonse deRochas created a piston
engine that compressed the gas within the cylinder
before ignition and placed it on a wheeled vehicle in
1862. Siegfried Marcus in Austria did the same in 1864.
When removed from a museum cellar in 1950 Marcus’s
vehicle was still drivable!
TURBINE ENGINES
By the middle of World War II, nearly every variation
of piston engines had been investigated. To get
more power required more cylinders; this meant more
cooling would be needed, and there was also a limit to
the speed at which propellers could turn. As the tips
approached the speed of sound, shock waves develop,
which cause a loss of performance. Thus propellers
had to actually be geared down as engine revolutions
per minute (rpm) increased.
ROCKET ENGINES
During World War II, the Germans developed a
rocket-propelled plane called a Komet. It was very fast
but ineffective mainly due to high fuel consumption.
After the war, the Bell Aircraft Company built the
rocket-powered Bell X–1. Launched from a B–29
bomber at 23,000 ft, the “Glamorous Glynnis” piloted
by Chuck Yeager reached a speed of Mach 1.06, or
1.06 times faster than the speed of sound. This broke
the sound barrier for the first time.