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![]() "markvictor" wrote in message oups.com... 3721 mph, but that would be in a submarine, not on the surface, at sea level, the nasa standard table puts SOS at sea level in daytime at 761mph...so that is what a surface vessel would have to achieve to break the sound barrier; even a displacement hull is still floating on the surface of th water, so it wold be subject to gas physics.A boat on the surface is exerting a fixed force on the water (in a perfect world), this force remains more or less constant, varying onle due to lift and loss of it while moving, this will not generate a fast enough shock wave through water to cause a "sonic boom" 741 mph in air at normal sea level pressure. In water at the surface, and for a long ways down, the density does not change much, the speed of sound would be 3000+ mph. Is why when diving, you can not tell which way a boat or sound is coming from. Ears, are not built to differentiate the time difference between the ears at those speeds. Air gets out of the way at supersonic speed, or the plane could not get through the air above the speed of sound. Sound is a pressure wave, and at the speed of sound all the pressure of the sound waves, piles up on the plane. So lots of buffeting and control surfaces lack response. Above the speed of sound, the pressure wave falls away from the plane to the rear. Similar to the bow way, now that I think about it. You have to climb the wave,and after you start to plane, you have left the bow wave behind. Takes power to overcome the bow wave pressure, but once on plane, you would require less power to stay on top. Of course to get on plane, you have to use enough power to lift the boat vertically some distance. |
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