Quote:
Originally Posted by JJW
The thread has progressed somewhat but I have a question which is somewhat related to the original question. I got to talk to an aerospace engineer once when I was a kid, and I asked how a rounded shape could be as aerodynamic as a cone shape (I think I said "more pointy" at the time) on the nose of model rockets. His response was that the round shape presented the same amount of area to the oncoming air as the pointy one, and slower than the speed of sound, they both did about as well to push the air to the sides of the rocket body.
Can anybody elaborate on if my memory from when I was about 11 is any good? If that is correct, and knowing a bit more now, it seems to me that the blunt shape does the job of getting the air attached to the sides via less surface area, and therefore less viscous drag than a long pointy cone-like shape which would have the same cross sectional diameter. (I'm a software engineer, not a mechanical engineer, so please excuse any confused terminologies!)
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It is spelled out in text that in subsonic flow,all streamlining basically occurs at the rear of the body(presuming flow is attached in the fore-body).At MACH 1 or higher,everything has to do with the nose.A convex hemisphere nose is considered more than adequate to guarantee fore-body attached flow in subsonic flow,and the air prefers the acceleration profile it provides over that of a straight walled conical nose section.Hucho's book demonstrates how little smoothing of leading edges is necessary for attached flow in the VW Rabbit development.A few chips off the ol' block is all that's necessary.