REFLECTOR: sparrow strainer (old post)

Pat Shea reflector@tvbf.org
Fri, 23 May 2003 11:41:32 -0700 (PDT)


Hi Alex,

I was thinking the reason the strainer is offset down
and back below the elevator/flap is to get it out of
the localized flow. It's not offset much, so you're
probably right. Thanks for the explanation.

Pat
 
--- Alexander Balic <alex157@direcway.com> wrote:
> Pat,
> The angle of the strainer to the line of flight is
> not really relevant
> because at the location of the sparrow strainer, the
> airflow is following
> the "elevator" (really flap), not the airflow at the
> leading edge of the
> canard, so it will stay relatively at the same angle
> of attack to the
> localized flow regardless of both aircraft angle of
> attack, and flap
> position. The reason that this airfoil is useful, is
> because at higher
> speeds, the flap sees a higher flow velocity, and
> tries to move upwards into
> the low pressure area behind the canard ( which
> would require stick UP/flap
> down to correct) so the sparrow strainer is inverted
> to help push the flap
> down, away from the tendency to float up into the
> low pressure area - I
> think that the problem that we are having here is
> that we think of the
> "elevator" as an "elevator" when it is actually a
> lift enhancing device for
> the canard, and therefore should be referred to as a
> flap, but since moving
> it results in pitch change, I can not really argue
> with the definition, but
> I think that we all must really think about what is
> going on aerodynamically
> to understand the purpose of the  trim system.
> 
> Alex



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