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Welcome to the NASA's Guide to Hypersonics
Image of hypersonic airplane
Hypersonic aerodynamics is a special branch of the study of aeronautics. The chief characteristic of hypersonic aerodynamics is that the temperature of the flow around the aircraft is so great that the chemistry of the gas must be considered. At low hypersonic speeds, the molecular bonds vibrate, which changes the magnitude of the forces generated by the air on the aircraft. At higher hypersonic speeds, the molecules break apart producing an electrically charged plasma around the aircraft. Large variations in air density and pressure occur because of shock waves, and expansions. Hypersonic aircraft typically have very thick boundary layers along the surface and high heat transfer to the surface. All of these high speed flow phenomena lead to a vehicle design unlike the typical airliner or fighter aircraft.

There are three principle aircraft missions to be considered in hypersonics; re-entry from orbit, hypersonic cruise, and hi-speed accelerator, which can be used as a re-usable booster. The first mission involves slowing a high speed vehicle while the latter two missions require a highly efficient propulsion system. Because of the high stagnation temperatures present at hypersonic speeds, a combination of gas turbine propulsion for low speed operations, ramjets for high supersonic propulsion , and scramjets for low hypersonic speeds has been proposed as a propulsion system. The transitions between the various modes of propulsion is an area of research. The only piloted hypersonic vehicles (X-15, Space Shuttle, and a variety of space capsules) have all been rocket powered.

At this Web site you can study hypersonic aerodynamics at your own pace and to your own level of interest. Some of the fundamental topics included are: isentropic flows, oblique, and normal shock waves, multiple shock interactions, and boundary layers. Because high speed aerodynamics involves the generation of heat, there are many pages devoted to basic gas properties, how those properties change through the atmosphere, and some basic thermodynamics.

This site was prepared at NASA Glenn to provide background information on hypersonic aerodynamics for undergraduates, professionals, and life-long learners. There is a particular emphasis here on the math and science involved with high speed aerodynamics. High school students should be able to make sense of the math and science principles. We include many, small, interactive calculators and simulators which solve the flow equations and are provided to aid your understanding.

This site has been intentionally organized to mirror the unstructured nature of the world wide web. There are many pages here connected to one another through hyperlinks and you can then navigate through the links based on your own interest and inquiry. There is an index of topics that you can access from any page, so you are never more than two clicks away from any other Web page at this site. However, if you prefer a more structured approach, you can also take one of our Guided Tours through the site. Each tour provides a sequence of pages dealing with some aspect of aerodynamics.

NOTICE --- The site has been developed to support Section 508 of the Rehabilitation Act. Many of the pages contain mathematical equations which have been produced graphically and which are too long or complex to provide in an "ALT" tag. For these pages, we have retained the non-compliant graphic at the top of the page and have provided a compliant text version of the equations in the body of the page. In many cases, because of the use of Greek fonts in the graphics, the purely English text version of the equations is slightly different than the graphic version. The differences are noted in the text.

Related Sites:
Beginner's Guide to Aerodynamics
Beginner's Guide to Propulsion
Beginner's Guide to Rockets


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Editor: Tom Benson
NASA Official: Tom Benson
Last Updated: May 07 2021

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