Supersonic speed
Supersonic speed is the speed of an object that exceeds the
Sounds are traveling vibrations in the form of pressure waves in an elastic medium. Objects move at supersonic speed when the objects move faster than the speed at which sound propagates through the medium. In gases, sound travels longitudinally at different speeds, mostly depending on the molecular mass and temperature of the gas, and pressure has little effect. Since air temperature and composition varies significantly with altitude, the speed of sound, and Mach numbers for a steadily moving object may change. In water at room temperature supersonic speed can be considered as any speed greater than 1,440 m/s (4,724 ft/s). In solids, sound waves can be polarized longitudinally or transversely and have even higher velocities.
Early meaning
The word supersonic comes from two Latin derived words; 1) super: above and 2) sonus: sound, which together mean above sound, or faster than sound.
At the beginning of the 20th century, the term "supersonic" was used as an adjective to describe sound whose frequency is above the range of normal human hearing. The modern term for this meaning is "ultrasonic".
Supersonic objects
The tip of a
Most modern
Most spacecraft are supersonic at least during portions of their reentry, though the effects on the spacecraft are reduced by low air densities. During ascent, launch vehicles generally avoid going supersonic below 30 km (~98,400 feet) to reduce air drag.
Note that the speed of sound decreases somewhat with altitude, due to lower temperatures found there (typically up to 25 km). At even higher altitudes the temperature starts increasing, with the corresponding increase in the speed of sound.
When an inflated balloon is burst, the torn pieces of latex contract at supersonic speed, which contributes to the sharp and loud popping noise.
Supersonic land vehicles
To date, only one land vehicle has officially travelled at supersonic speed, the ThrustSSC. The vehicle, driven by Andy Green, holds the world land speed record, having achieved an average speed on its bi-directional run of 1,228 km/h (763 mph) in the Black Rock Desert on 15 October 1997.
The Bloodhound LSR project planned an attempt on the record in 2020 at Hakskeenpan in South Africa with a combination jet and hybrid rocket propelled car. The aim was to break the existing record, then make further attempts during which [the members of] the team hope to reach speeds of up to 1,600 km/h (1,000 mph). The effort was originally run by Richard Noble who was the leader of the ThrustSSC project, however following funding issues in 2018, the team was bought by Ian Warhurst and renamed Bloodhound LSR. Later the project was indefinitely delayed due to the COVID-19 pandemic and the vehicle was put up for sale.
Supersonic flight
Most modern
The
However, in practical applications, a supersonic aircraft must operate stably in both subsonic and supersonic profiles, hence aerodynamic design is more complex.
The main key to having low supersonic drag is to properly shape the overall aircraft to be long and thin, and close to a "perfect" shape, the
See also
- Area rule
- Hypersonic speed
- Sonic boom
- Supersonic aircraft
- Supersonic airfoils
- Transonic speed
- Vapor cone
- Prandtl–Glauert singularity
References
- ^ "APOD: 2007 August 19 - A Sonic Boom". antwrp.gsfc.nasa.gov.
- ^ "F-14 CONDENSATION CLOUD IN ACTION". www.eng.vt.edu. Archived from the original on 2004-06-02.
- ^ Mike May (2002). "Crackin' Good Mathematics". American Scientist. 90 (5). Archived from the original on 2016-03-22. Retrieved 2015-08-26.
- ^ "Hypography – Science for everyone – Whip Cracking Mystery Explained". Archived from the original on 2012-02-17. Retrieved 2008-02-06.
- ^ "Does the Tip of a Snapped Towel Travel Faster Than Sound?".
- ^ "Hornady Ammunition Charts" (PDF). Archived from the original (PDF) on 2007-09-27. Retrieved 2011-11-04.
External links
- "Can We Ever Fly Faster Speed of Sound", October 1944, Popular Science one of the earliest articles on shock waves and flying the speed of sound
- "Britain Goes Supersonic", January 1946, Popular Science 1946 article trying to explain supersonic flight to the general public
- MathPages - The Speed of Sound
- Supersonic sound pressure levels