[Phys-L] Re: the plane truth

[Bernard Cleyet <bernardcleyet@REDSHIFT.COM>]

John's barn door, as wing, reminds me of kites.  They have lotsa lift
and are usually quite flat.

Now my question:  A spherical, He filled, balloon tethered will be
brought down, say the tether to 45 deg.?, by a stiff wind.  How may one
design a balloon to be less affected by wind?

I thought drag may be reduced by using a lenticularly shaped balloon and
lift increased by using the balloon to tether a kite.

Comments and assistance please.

bc, who thinks the only reason wings are thick is to hold fuel (joke)

John Denker wrote:

> Roger Haar wrote:
>
>
>
> >        Airplane wings are actually fairly complex.
>
> Fluid dynamics in general is horrendously complex.
>
>
>
> > Air
> > moving faster over the top is fairly simple.
> > Consider a wing that has the following
> > cross-section.  A one meter long straight flat
> > bottom and a half circle on top.  The air passing
> > along the bottom travels a 1 meter path length.
> > The air that starts at the leading edge and goes
> > over the top travels a distance of pi/2.  This is
> > not a very good wing, but it illustrates the
> > idea.
>
> No, that is a completely bogus wing and is completely
> false and misleading with respect to what's really
> going on.  For one thing, it makes a completely false
> prediction about the dependence of lift on angle of
> attack.
>
> This "wing" has been re-invented many times.  Even
> Albert Einstein got in on the act, proposing _multiple_
> bumps on the top side.  It remains, however, completely
> bogus, as Uncle Al soon realized.
>
>
>
> > ( My favorite quick demo of this is a spoon in the
> > flow of a facet the is only partially open.  Hold
> > the spoon vertically by its handle. Have the water
> > flow over the curved bask of the spoon. The spoon
> > will be pulled into the stream, and you can see
> > the deflection of the stream of water.)
>
> Also completely bogus.
>   http://www.av8n.com/how/htm/spins.html#sec-teaspoon-effect
>
>
>
> >        Air that is split by the passing of a wing, does
> > not have to rejoin at exactly the same place.  The
> > upper air might lag a bit, but the amount of lag
> > cannot continually increase, otherwise there would
> > eventually be a huge pile of air someplace.
>
> Diametrically false.  The air going over the top arrives
> at the back substantially _earlier_ than the corresponding
> air passing under the wing, as required by the Kutta-Zhukovsky
> theorem.
>   http://www.av8n.com/how/htm/airfoils.html#sec-k-z
_______________________________________________
Phys-L mailing list
Phys-L@electron.physics.buffalo.edu
https://www.physics.buffalo.edu/mailman/listinfo/phys-l