NASA Logo - Web Link to NASA.gov

+ Text Only Site
+ Non-Flash Version
+ Contact Glenn

Go
ABOUT NASA NEWS AND EVENTS MULTIMEDIA MISSIONS MyNASA WORK FOR NASA
Computer drawing of kids page link
This page is intended for college, high school, or middle school students. For younger students, a simpler explanation of the information on this page is available on the Kid's Page.

Photo of a subsonic aircraft
 with some of its characteristics

As an aircraft moves through the air, the air molecules near the aircraft are disturbed and move around the aircraft. Exactly how the air re-acts to the aircraft depends upon the ratio of the speed of the aircraft to the speed of sound through the air. Because of the importance of this speed ratio, aerodynamicists have designated it with a special parameter called the Mach number in honor of Ernst Mach, a late 19th century physicist who studied gas dynamics.

For aircraft speeds which are very much less than the speed of sound, the aircraft is said to be subsonic. Typical speeds for subsonic aircraft are less than 250 mph, and the Mach number M is much less than one, M << 1 . For subsonic aircraft, we can neglect compressibility effects and the air density remains nearly constant.

The first powered aircraft to explore this regime was the Wright Brothers' 1903 flyer. Modern general aviation and commuter airliners continue to fly in this speed regime. At such low speeds, propellers provide a very fuel efficient propulsion system. On the slide we show a C-130 cargo aircraft which is powered by four turboprop engines. The wings of subsonic aircraft are typically rectangular in planform and made of light weight aluminum, although the Wrights used wood and cloth in their wing construction.


Activities:
Guided Tours


Navigation ..

Button to Display Propulsion Index Button to Display Aerodynamics Index Button to Display Hi Speed Aero Index
Beginner's Guide Home Page

 

     First Gov Image


+ Inspector General Hotline
+ Equal Employment Opportunity Data Posted Pursuant to the No Fear Act
+ Budgets, Strategic Plans and Accountability Reports
+ Freedom of Information Act
+ The President's Management Agenda
+ NASA Privacy Statement, Disclaimer,
and Accessibility Certification

 

NASA Logo   
Editor: Tom Benson
NASA Official: Tom Benson
Last Updated: Jun 12 2014

+ Contact Glenn