Re: [Phys-l] Bernoulli, Coanda, or Lanchester-Prandtl

[Bernard Cleyet <bernardcleyet@redshift.com>]

My point to RAFT is not to use a reference that is claimed, by knowledgable people, wrong.

However, JD's reference to statement:  
> One can go further and say that the spoon effect has got nothing
> to do with the mechanism by which wings produce lift (which has
> also got virtually nothing to do with the Coanda effect). 

Indicate he didn't read Terry's page carefully, as he wrote, In addition to his spoon error:

 "Just so you know, there is no Coanda lift on an airfoil."

And, inter alia,:

More misleading "lift" explanations

      Clashing Balloons: Hang two balloons from strings an inch or so apart. Blow a stream of air between them and they move together. Now, I show a wind sprite in the picture, but if one is not around do it yourself.

http://www.terrycolon.com/1features/ber.html

--------------------------

On 2011, Sep 01, , at 10:14, LaMontagne, Bob wrote:

> I'm having a hard time visualizing this. Are you floating the bowl of the spoon in a container of water?
>
> Bob at PC


Initially, except, I'm rather certain it'd sink.  Better cut off the handle, attach three threads to the edges and pulley it up w/ a force gauge.  Even better (JD's experiment.?) have the water smoothly flowing at various rates.

bc

--------------------------

On 2011, Sep 01, , at 10:47, John Denker wrote:

> On 09/01/2011 06:36 AM, chuck britton wrote:
> > This 'Back of spoon pulled into stream of water' is a very poor 
> > (perhaps wrong?) illustration of the Coanda Effect
>
> Agreed.  The spoon effect has got nothing to do with Coanda.
>
> > since the 
> > 'Entrained Fluid' would be air which doesn't provide enough reaction 
> > force. 
>
> That argument is correct and sufficient to prove the point.
>
> Also by looking at the water downstream you can see that there's
> no entrained air.
>
> > Surface tension is a better explanation of this observed 
> > effect (IMHO).
>
> Also correct.  I've done some experiments.
>
> One easy experiment is to measure the magnitude of the spoon
> effect as a function of the velocity of the water stream.  It
> doesn't scale the way the Coanda effect would scale.
>
> One can go further and say that the spoon effect has got nothing
> to do with the mechanism by which wings produce lift (which has
> also got virtually nothing to do with the Coanda effect).  So
> explaining lift in terms of Coanda as illustrated by the spoon
> is completely wrong twice over.
>
> ============================
>
> Whatever happened to the idea of "check your work"?
>
> Isn't that supposed to be taught in 2nd grade and every grade
> thereafter?
>
> Feynman said that if you want to be a scientist, "The first 
> principle is that you must not fool yourself -- and you are
> the easiest person to fool."
>  http://www.lhup.edu/~DSIMANEK/cargocul.htm
>
> Science is a collection of procedures for finding the right
> answers and avoiding mistakes.  The first principle for
> preventing mistakes is to realize that mistakes are possible.
> So check your work!
>
> These guys who publish articles explaining lift in terms of
> Coanda as illustrated by the spoon ... did they think about it
> even for a femtosecond?  Did they even /consider/ the possibility
> that they might be making a mistake?
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