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Weekly Online LessonOnline Lesson ArchiveGrade Level: 9-12
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Jet Engine Technology
On
November 1, 2001, a HyShot supersonic combustion ramjet (scramjet) capable
of flying more than seven times the speed of sound was launched on the
back of two rockets at a Woomera testing area in Australia. The test flight
failed, but scientists were upbeat about their efforts to achieve the
world's fastest combustion flight.
The scramjet propulsion system uses different kind of technology
than traditional rockets. Instead of carrying both fuel and oxygen to
ignite, the scramjet uses oxygen in the atmosphere. To get the oxygen
to ignite the fuel, it needs to take the oxygen into its combustion chamber
at extremely high speeds. The HyShot scramjet is designed to combust at
Mach 7.6, nearly eight times the speed of sound. The speed of sound is
about 1,200 km (750 miles) per hour.
Unlike today's jet engines, the scramjet has no moving parts so it won't burn up at extremely high speeds. The technology could one day be used to dramatically reduce flying time, cutting a London to Sydney flight to two hours.
In this week's online lesson you will learn about jet engines and the emerging scramjet technology.
The Gas-Turbine Primer
Jet
engines are a type of gas-turbine engine in which air is pressurized,
mixed with fuel, and then burned. The resulting hot gas is allowed to
escape and perform various kinds of work, such as propelling a commercial
jet airliner forward. To learn more about gas-turbine theory and history,
visit Basic
Gas-Turbine Theory. This page features helpful graphics and simple
explanations that make the technology easy to understand.
Browse through the gas-turbine engine illustrations, and then focus on the history section on the second half of the page. What is the earliest known example of jet propulsion? Who patented a design for the first jet aircraft engine in 1930?
Glenn Research Center Tutorials
You
can learn more about the basics of gas-turbine
propulsion at NASA's Glenn Research Center. This tutorial briefly
discusses the physics of propulsion and gives an overview of jet engines
since World War II. What is Newton's third law, and how does it apply
to jet engines?
Click Next to move from there to Gas Turbine Parts. This page shows a static image of a Pratt & Whitney F100 engine used in the F15 and F16 fighter aircraft. There are six main parts common to all jet engines, as you can see from the labels on the graphic. What is the function of each part?
Static graphics are fine, but you can see the jet engine in action by clicking animated version. Use the controls below the graphic to animate the image (for example, click Turn Engine to see the compressor and turbine blades in motion).
UTC Discovery Center
The
United Technologies site (parent company of jet engine manufacturer Pratt
& Whitney) features a discovery center with a great How it Works
section on Jet
Engines. First read the paragraph in red (below the engine illustration)
and the introduction below it for an overview on jet propulsion. Now comes
the fun part. Scroll back up to the top of the page and roll your mouse
pointer over the numbers 1 through 6. You will see an animation and explanation
of that element. What does each part do? How much air passing through
the engine is bypass air? How much of the overall thrust does bypass air
provide?
If you're really interested in jet engine technology and want more details (but without all the technical language), try the Rolls-Royce How a Gas Turbine Works tutorial. Start with the Introduction and click Next Page at the bottom of each page to continue through the tutorial.
Hypersonic Air-Breathing Engines
If
you have time for one more site, read the February, 1999 Scientific American
article by Charles R. McClinton entitled "Air-Breathing
Engines." This article isn't exactly up-to-date, but McClinton
gives a good description of how ramjet and scramjet engines work and why
they can attain such high speeds. What advantages do air-breathing engines
have over rocket engines?
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Learners Online, Inc.