Snaps

[Jerry Budd]

Not quite.

A wing is stalled when the lift curve slope changes sign, meaning 
that a further increase in angle of attack (AOA) results in a 
reduction in lift, due to increased separation of the airflow 
disrupting the pressure distribution over the top of the wing.  The 
AOA (also refered to as "alpha" in the flight test world) at which 
the lift curve slope changes from positive to negative is where the 
maximum lift coefficient (CL-max) of the wing (or vehicle) is reached 
and is typically found to occur around 18 to 30 degrees alpha.  It's 
a function of a whole lot of things like aspect ratio, planform, 
control surface deflection, Reynolds #, Mach#, etc.  It is NOT a 
function of airspeed.

But I digress...

Jerry


>I was taught that a wing is stalled when it will no longer support the
>aircraft in flight. You would be losing altitude if in level flight until
>airflow is returned over the wing to support the weight of the aircraft.
>Granted this is over simplification but when you ask about laminar flow
>separation I understood that you can have separation when in a well trimmed
>plane and still not lose much altitude but I believe this is getting into
>semantics and not germane to models being judged for snapping or not
>snapping.
>
>                          del
>                NSRCA - 473
>----- Original Message -----
>From: "Adam Glatt" <adam.g at sasktel.net>
>To: <discussion at nsrca.org>
>Sent: Wednesday, April 14, 2004 10:44 AM
>Subject: Re: Snaps
>
>
>>  Isn't the definition of a stalled wing just that it doesn't have laminar
>>  flow?  That is entirely possible in a downline with sharp elevator input
>  > (think less extreme version of a TOC plane's parachute or wall).

-- 
___________
Jerry Budd
mailto:jbudd at qnet.com
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