The term Transonic refers to a range of velocities just below and above the local speed of sound ( generally taken as Mach 0. 8 – 1. 2 ).

It is defined as the range of speeds between the critical Mach number, when some parts of the airflow over an aircraft become supersonic, and a higher speed, typically near Mach 1. 2, when all of the airflow is supersonic.

A smokeless, solid-propellant, booster-sustainer rocket motor propels the missile at speeds over Mach 2.

* Speed: Mach 2. 3

The sound barrier was broken, and after a few false starts due to required changes in controls, speeds quickly reached Mach 2 — past which aircraft can't maneuver to avoid attack.

The BrahMos cruise missile which is a joint venture between India and Russia, is the fastest cruise missile in the world with a top speed of Mach 2. 8-3.

* 1970 – The Soviet Tupolev Tu-144 becomes the first commercial transport to exceed Mach 2.

Because the Mach number is often viewed as a dimensionless quantity rather than a unit of measure, with Mach, the number comes after the unit ; the second Mach number is " Mach 2 " instead of " 2 Mach " ( or Machs ).

Mach received a major boost in visibility when the Open Software Foundation ( OSF ) announced they would be hosting future versions of OSF / 1 on Mach 2. 5, and were investigating Mach 3 as well.

Mach 2. 5 was also selected for the NeXTSTEP system and a number of commercial multiprocessor vendors.

When Mach was first being seriously used in the 2. x versions, performance was slower than traditional monolithic operating systems, perhaps as much as 25 %.

For instance, the L4 kernel ( version 2 ) includes only seven system calls and uses 12k of memory, whereas Mach 3 includes about 140 functions and uses about 330k of memory.

The ratio of the flow speed to the speed of sound was named the Mach number after Ernst Mach, who was one of the first to investigate the properties of supersonic flow which included Schlieren photography techniques to visualize the changes in density.

Because of the increase in drag approaching Mach 1, aerodynamicists and aviators disagreed on whether supersonic flight was achievable.

Image showing shock waves from NASA's X-43A hypersonic research vehicle in flight at Mach 7, generated using a computational fluid dynamics algorithm. On September 30, 1935 an exclusive conference was held in Rome with the topic of high velocity flight and the possibility of breaking the sound barrier.

A contrasting position was taken by Ernst Mach, who contended that all motion was relative.

It was designed to fly below the enemy's radar at speeds above Mach 3 and carry a number of hydrogen bombs that it would drop on its path over enemy territory.

Work on this was delayed for three years due to uncertainty over whether CMU would release the Mach code under a suitable license.

From early on, the Hurd was developed to use GNU Mach as the microkernel.

The engine was intended to switch from jet propulsion to pure rocket propulsion at 26 – 32 km high, by which time the craft would be travelling at Mach 5 to 7.

However, some scientists ( called " relativists " by Mach ), even at the time of Newton, felt that absolute space was a defect of the formulation, and should be replaced.

Mach argued, beginning in the 1880s with The Science of Mechanics ( 1883 ), that the mind had a fundamental structure, and that subjective experience was based on the interplay of parts of the mind.

As a philosopher of science Ernst Mach was a major influence on logical positivism, and through his criticism of Isaac Newton, a forerunner of Einstein's theory of relativity.

Although the existence of molecules has been accepted by many chemists since the early 19th century as a result of Dalton's laws of Definite and Multiple Proportions ( 1803 – 1808 ) and Avogadro's law ( 1811 ), there was some resistance among positivists and physicists such as Mach, Boltzmann, Maxwell, and Gibbs, who saw molecules merely as convenient mathematical constructs.

The first microkernels, notably Mach, proved to have disappointing performance, but the inherent advantages appeared so great that it was a major line of research into the late 1990s.

It was a sardonic response to Mach, which claimed to be a microkernel while being monolithic, essentially unstructured, and slower than the systems it sought to replace.

This is somewhat reminiscent of the early modern ocean sounding unit " mark " ( a synonym for fathom ), which was also unit-first, and may have influenced the use of the term Mach.

The project at Carnegie Mellon ran from 1985 to 1994, ending in apparent failure with Mach 3. 0, which was finally a true microkernel.

Mach was developed as a replacement for the kernel in the BSD version of UNIX, so no new operating system would have to be designed around it.

The Mach virtual memory management system was also adopted by the BSD developers at CSRG, and appears in modern BSD-derived UNIX systems, such as FreeBSD.

Another of the original Mach developers, Avie Tevanian, was formerly head of software at NeXT, then Chief Software Technology Officer at Apple Computer until March 2006.

In theory the microkernel design would allow for all device drivers to be built as servers working in user space, but today most drivers of this kind are still contained in the GNU Mach kernel space.

A small team had built Mach and ported it to a number of platforms, including complex multiprocessor systems which were causing serious problems for older-style kernels.

It is unusual among commercial UNIX implementations, as it is built on top of the Mach kernel developed at Carnegie Mellon University.

( Other UNIX implementations built on top of the Mach kernel are NeXTSTEP, MkLinux Mac OS X and Apple iOS.

Amplitude modulators can be built by putting the electro-optic crystal between two linear polarizers or in one path of a Mach – Zehnder interferometer.

Darwin is built around XNU, a hybrid kernel that combines the Mach 3 microkernel, various elements of BSD ( including the process model, network stack, and virtual file system ), and an object-oriented device driver API called I / O Kit.

NACA built a handful of new high-speed wind tunnels, and Mach 0. 75 ( 570 mph, 920 km / h ) was reached at Moffett's wind tunnel late in 1942.

In the manga and anime this is the car's racing number ; in the film, it is portrayed as the fifth car built in Pops ' " Mach " series of racing vehicles.

In both American comic and movie continuity, Pops is portrayed as having built a " Mach " Series consisting of other variants such as the Mach 4 and Mach 6 in addition to Rex Racer's Mach 1 and the Mach 5.

The car was the only car built in addition to the Mach Five for the movie, and features weapons like machine guns mounted above the cockpit and under the chassis.

After Taylor deploys the device against Speed during the Grand Prix, Speed uses the Mach 6's auto-jacks to flip the cars and reveal the hook to the track cameras, automatically disqualifying Taylor and aiding the case built by Inspector Detector against Royalton.

As the ramjet only operates effectively at high speeds over Mach 1, Bristol built a series of testbed airframes to flight-test the engines.

With Mac OS X, the designers have attempted to streamline certain tasks and thus BSD functionality was built into the core with Mach.

The Mach V models were built with components that Falcon Northwest believed to offer the highest performance in PC games.

Riedl built upon the work of the Viennese school of thought initially typified by Konrad Lorenz, and continued today by Gerhard Vollmer, Franz Wuketits, and in Spain by Nicanor Ursura, skeptical of German idealism, and nourished by the tradition that produced Ernst Mach, Ludwig Boltzmann, Erwin Schrödinger, Karl Popper, Hans Reichenbach and Sigmund Freud.

The second Racer was designed by John Miller in 1927 and built by Charile Mach.