Quote:
Originally Posted by Piwoslaw
How about A-B-A testing:
Two identical teardrops (same size, weight, etc.).
One teardrop has pointy nose added.
Drop from tall tower.
Tower height small to ensure subsonic speed at bottom.
Wife at bottom with stopwatch.
Pad and pencil (or spreadsheet).
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Those are what bullets are. It is well known that pointed bullets are faster, even the subsonic airgun pellets, and they penetrate any fluid with less resistance, including water and air.
The problem is that if the point is too long, it causes directional instability. Pointed nosed tear drops dropped from a tower wouldn't fall straight without tail fins like a dart to make them spiral.
And depending what speed they are operated at, there are diminishing returns where the extra surface area causes more friction.
Looking back at that chart, you can see that the highest value of pressure, either positive or negative, is directly in front of the traveling sphere, where the surface is at a 90 degree angle to the oncoming air. The lowest pressure is not behind the ball, but at the point in front where the airflow is about half way between perpendicular and parallel with the surface.
By making the nose of bullets and airplanes parabolic rather than hemispherical, both the pressure and the volume of the pressurized air in front of the object are greatly reduced.