Re: Archie a non-flyer? (was:Re: origin of bats/reply 2 to TMK)

[jrc <jrccea@bellsouth.net>]

Comments inserted.
JimC

----- Original Message ----- 
From: "Roberto Takata" <rmtakata@gmail.com>
To: "jrc" <jrccea@bellsouth.net>
Cc: <dinosaur@usc.edu>
Sent: Thursday, June 26, 2008 11:23 AM
Subject: Re: Archie a non-flyer? (was:Re: origin of bats/reply 2 to TMK)


> On Thu, Jun 26, 2008 at 7:29 AM, jrc <jrccea@bellsouth.net> wrote:
> > > One will have problem if do not restrict flow direction in the
> > > analysis - specially if consider a flow parallell to gravity
> > > acceleration.
> >
> > One will have a problem if they do restrict flow direction.  With that
> > restriction, you are no longer modeling what's happening to the airfoil.
>
> Nope, since one will analyse lift here. Deviation from horizontal flow
> must be translated into more or less lift - or differential pressure
> over the wing faces.

'Fraid not, Roberto.  You do a vector sum of all the pressures normal to the 
airfoil surface all the way round the airfoil.  If you don't, you will have 
problems.  We're talking about pretty basic aerodynamics here.

> > For a non-cambered wing at positive angle of attack, the leading 
> > stagnation
> > line shifts away from the leading edge to a line on the lower surface 
> > near
> > the leading edge, and the flow above that line reverses, accelerates
> > forward, around the leading edge, and aft over the top of the wing at 
> > high
> > velocity.
>
> Why the air above the stagnation line will accelerate in (I)? And the
> air bellow stagnation line will accelarate in (II)?

Because of the different position of the stagnation line relative to the 
leading edge of the airfoil.

I'm gonna be off-line for a couple of days, but I expect Mike will take up 
the slack, and we usually make similar responses.  Ball's in your court, 
Mike.

All the best,
JimC