The Two Types of Sonic Booms and Strengths

Two types of sonic booms are identified by the US Military, namely the U-wave and the N-wave. The U-wave is a focused sonic boom which created by maneuvering flights and the shock waves are shaped like a “U”. It has positive shock waves, both at the front and the tail of a boom during which peak overpressures increases.
The N-wave is created by steady flying conditions, with N-shaped pressure waves. The N-wave has front shock waves to peak over pressure and follows with a decrease in pressure towards the tail end to return to ambient pressure.
The peak overpressure in an N-wave can vary from under one pound to over ten pounds per square foot, during normal operating conditions. A U-wave’s peak overpressures is double and sometimes up to five times the amount, with the amplified overpressure impacting a small area when you compare it to the exposed area left by the sonic boom.
Realistic flight conditions recently recorded a sonic boom of twenty one pounds per square footage. If a building is in good condition it may still be damaged if flight altitude is low. Buildings in worse condition will suffer some serious damage from a sonic boom of that magnitude. Good buildings can even sustain damage from sonic booms with sixteen pound shock wave overpressure and generally less than sixteen pounds are acceptable to cause little or no damage.
Researchers tested the ultimate strength of sonic boom and without sustaining any injury they measured a massive boom of one hundred and forty –four pounds per square foot. An F-4 aircraft was used during this experiment, travelling at low altitude of hundred feet with speed just higher than the speed of light. Ground motion from sonic boom is generally below two pounds and the U.S. Bureau of Mines finds that well within the accepted structural damage threshold.

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