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

```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