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Re: Europa-List: Votex Generators

Subject: Re: Europa-List: Votex Generators
From: flyingphil2 <ptiller@lolacars.com>
Date: Fri, 11 May 2007 12:33:53

This is developing into quite a discussion.  I'm an aerodynamicist by trade and
so here's my answers to the points above:

1.  If someone wants to try VGs on a Europa then go ahead but I suspect they 
won't make any difference.  The wing design is far more advanced than those 
seen on www.landshorter.com which tend to be things like the Kitfox etc.  VGs 
may improve flow over the ailerons which will make the aircraft feel better at 
slow speeds and will improve controllability near the stall.  With a poor wing 
design they may reduce the stall speed.  Don Dykins used a lot of his (and his 
department's) experience in the Europa wing and that was previously used on 
aircraft like the BAe 146 and early Airbus.

2.  Graham is right about the Long Eze and the way in which the VGs helped.  I
guess the laminar region on the canards was probably the first 25% of the chord
and there was a trailing edge separation.  The Europa is designed to have a
larger laminar region with no separation and so the VGs will not help in this
case.

3.  To reduce the stall speed on the Europa you would need to have a more 
powerful
flap with maybe an additional 'flap vane' ahead of the main flap or something
like leading edge slats.  You could try a 'blown' wing as well if you were
keen.  

On another point:

NACA intakes are designed to be an efficient and low drag intake method.  The 
edges
of the intake generate small vortices which the flow down the intake and
they work very well indeed if positioned in the right place.  I think Duncan's
issue may be down to a positioning problem and you won't improve the flow down
that duct with a VG at high aoa if the flow isn't going that way in the first
place.  That brings me on to another point.  I routinely run large computer
simulations of external aerodynamic cases in my job.  I'm quite keen to look at
a Europa but need some CAD geometry.  The factory doesn't have any as the moulds
were hand made so my question is has anyone, who has too much spare time
on their hands, made a good quality CAD representation of a Europa?  I know 
there
are some models floating round for flight simulators but they are far too
basic for what I would need.

Regards,

Phil


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