Visibility of plainly decoupled precursor flow (the pressure measured from compression and subsequent overpressure pulse through the air column in the gun barrel by the bullet prior to bullet exit) is rarely seen in the sound signature of a suppressed small arm weapon system. As always, internal silencer design can significantly influence the measured timing and pressure amplitudes. This is a highly unusual sequence observed when firing subsonic 300 BLK ammunition from a bolt-action weapon system with an attached silencer the precursor flow being plainly visible prior to muzzle blast is a phenomenon resulting from the extremely high flow rate of the OSS technology. The maximum peak pressure amplitude of the first shot the primary muzzle blast flow coupled with the bullet endcap exit event, is measured to be 155.8 dB. Prior to muzzle blast exit, peak precursor flow is measured to reach a peak of 134.9 dB. There are four significant events shown:ĭuring combustion within the weapon system, a 121.1 dB peak is measured.Īs the precursor flow exits the silencer’s endcap vent array, a peak of 128.6 dB is measured. It is the speed traveled by rockets and the space shuttle as they go into orbit.Figure 1 shows a 2-millisecond long sequence of events during the first test shot with the OSS HX-QD 762, as measured 1.0 m left of the muzzle. This is more than five times the speed of sound. This is the speed traveled by most of the commercial airplanes that carry people and cargo. (Speeds listed below are based on Earth’s atmospheric conditions.) The computerized simulations are commonly referred to as computational fluid dynamics, or CFD. Other experimental aircraft tested new materials that could be used to make faster airplanes.Ī third way NASA learns about supersonic flight is through computer simulations. Aircraft such as the XB-70 (also called the Valkyrie) and the X-29 tested new wing designs. Nine years later, in 1956, the X-2 became the first aircraft to reach Mach 3, or three times the speed of sound. In 1947 the first X-plane, called X-1, was the first aircraft to break the sound barrier. The “X” in X-planes comes from the letter “x” in the word “experiments.” X-planes test new designs and new technologies to improve flight. These aircraft are called X-planes because the aircraft are used for experiments. Navy and aircraft manufacturers to build experimental aircraft. NASA has been involved in supersonic flight experiments since the 1940s. Researchers also fly actual supersonic aircraft that have been modified for research experiments. They help researchers to learn more about how an aircraft will fly and to test new designs. Wind tunnels are tube-shaped facilities that move air over a vehicle as if it were flying. NASA researchers can simulate supersonic flight by using small models of aircraft in wind tunnel experiments. NASA studies supersonic flight in three ways. NASA is studying and testing devices that could be used on aircraft to lessen the noise and window-rattling effects of supersonic flight. It is similar to the sharp release of pressure when a pin pops a balloon and makes a loud noise. A sharp release of pressure after the buildup of a shock wave is heard as a sonic boom. The shock wave forms a cone of pressurized air. This force forms a shock wave, much like the wave created by the front, or bow, of a boat moving in water. As objects travel through the air, the air molecules are pushed aside with great force. Air reacts like a fluid to supersonic objects. What Is a Sonic Boom?Ī sonic boom is a loud, thunder-like noise heard by a person on the ground when an aircraft flies overhead at supersonic speeds. That is about half the amount of time it would take typical airliners to fly the same distance. It could fly people from London to New York in less than 3 1/2 hours. The Concorde’s maximum speed was more than twice the speed of sound. The space shuttle orbiter flies at supersonic speeds during portions of its mission.Īn airplane called the Concorde was the most notable passenger airplane to travel at supersonic speeds. Military fighter aircraft also fly this fast. A bullet fired from a gun is an example of an object that flies at supersonic speeds.
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