George Lednicer wrote:

To all,
Everyone talks of the speed of sound and how the prop tip must be kept below
the speed
of sound (which is correct )- to the novice/uninformed this is only half the
info in regard to
understanding WHY !
Although I don't really understand it all, the reasons or explanations given
to me are:-
1. The prop tip does some crazy things when it exceeds the sound barrier
(I found this one really informative)
2. The prop loses lift when it excceeds the sound barrier
3. Things go into reverse when the sound barrier is exceeded

Now that I have been told these things I feel totally and fully informed -I
don't think !!

However it does give me some understanding, if someone wants to expand upon
this
I would be forever grateful.
George(down under)

When I was in college studying physics my professors would tell me these things
and I felt the same way. Here is how it works. Some guy tried it and that is what
happened :-) So another guy tried it and it happened to him too. Several others
also tried it with the same results and it became a law of physics. Nothing more
nor less than this. Why it does what it does is another matter.
See the page below from the classic book "Theory of Wing Sections"
by Abbott & Von Doenhoff

The ratio of the diameter to the circumference of a circle is
pi. Why! Some Greek guy drew a bunch of different size circles in the sand 
several thousand years ago  and measured the circumference and the diameters 
and found that they all came out to the same ratio 3.1416xxxxxxxxxxxxxxxx

Paul Lamar
 
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