An explosion sound that is felt on the ground, caused by the shock wave of a supersonic aircraft. When the shock waves of an aircraft flying at supersonic speed (2 to 5 times the speed of sound) are generated from various parts of the aircraft, they merge at a sufficient distance from the aircraft to form two approximately cone-shaped wavefronts. This causes two consecutive instantaneous pressure rises at the point where the wavefront passes on the ground, which is felt by the human body as an impact sound (explosion sound). This pressure rise is usually 1 to 2 hectopascals, for example, 14.7 kilograms per square meter (similar to nearby thunder) at an altitude of 6,100 meters, and 4.9 kilograms per square meter (similar to distant thunder) at an altitude of 12,200 meters. Although the numerical value is not so large, it is felt as a loud sound. Since the explosion sound is felt suddenly, it has a large psychological impact on people and animals, and if the strength increases, it can have a negative impact on buildings, such as breaking window glass. The strength of the boom varies depending on the aircraft's flying altitude, Mach number (flight speed), size and weight of the aircraft, etc., so its effects can be eliminated by selecting the aircraft's shape, flying speed and flight course. [Kazuo Ochiai] ©Takashi Aoki Shock waves caused by supersonic flight (sonic boom) Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend |
超音速航空機の衝撃波によっておこされ、地上で感じられる爆発音。超音速(音速の2~5倍の速度)で飛行する航空機の機体各部から生じた衝撃波は、機体から十分に離れた場所では統合されて近似的な円錐(えんすい)状の二つの波面を形成する。このため、地表におけるその波面の通過地点では2回の連続した瞬間的な圧力上昇を生じ、人体には衝撃音(爆発音)として感じられる。この圧力上昇は通常1~2ヘクトパスカル、たとえば飛行高度6100メートルでは14.7キログラム毎平方メートル(近くの雷程度)、1万2200メートルでは4.9キログラム毎平方メートル(遠雷程度)で、数値的にはそれほど大きなものではないが、音としては大きく感じられる。突然爆発音を感じることになるので、人や動物に与える心理的な影響は大きく、強さが大きくなれば窓ガラスの破損など建物にも悪影響を及ぼすようになる。ブームの強さは航空機の飛行高度、マッハ数(飛行速度)、航空機の大きさ、重量などにより変化するため、航空機の形や飛行速度、飛行コースを選択してその影響を除くことができる。 [落合一夫] ©青木 隆"> 超音速飛行による衝撃波(ソニックブーム… 出典 小学館 日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について 情報 | 凡例 |
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