REFLECTOR: Cowl Vortex generators

[Douglas Holub]

There was a seminar at Oshkosh 2007 about cooling canard aircraft and one of 
the slides showed VGs on the side of a cowl. The oil streaks showed that the 
VGs did indeed keep the air attached as the cowl curved around.

Doug Holub
28.6 hours to go
----- Original Message ----- 
From: "Rene Dugas" <dugasd at bellsouth.net>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Sunday, March 29, 2009 1:21 PM
Subject: Re: REFLECTOR: Cowl Vortex generators


> Vortex generation got me to thinking about keeping air flow attached  for 
> a longer arc near the prop between the exit holes in the cowl and  the 
> prop. If the airflow stayed attached longer it might supply less 
> disrupted air to the prop. This may be too close to the prop root to  make 
> difference. It might increase the drag by forming more vacuum but  that 
> might improve cowl evacuation.  VG's leading the NACAs helps. Two  pairs 
> on each top and two on the lower cowl 6 or 8 inches forward of  the 
> groove-might have a benefit. I've thought whether our exits should  be 
> rectangular to decrease air flow disruption.  Food for rumination.  Also 
> would VG's 6" forward of the ailerons make them more effective at  slow 
> speeds similar but for different reasons to fences.
>
> Rene' Dugas
> Sent from my iPhone 3G
>
> On Mar 28, 2009, at 8:37 AM, Scott Derrick <scott at tnstaafl.net> wrote:
>
>> As ken says, the factory has a template set for placing the VG's.  I
>> believe you normally get a set of  factory  VG's with the  templates.  5
>> years ago I convinced them to sell me the templates, sans VG's for a
>> reduced price.  Maybe you can do the same..   Most of their cost was  in
>> the placement engineering and testing so the reduction in price wasn't
>> enormous, which was fine by me.
>>
>> Personally, I wouldn't  install them without the factory templates.
>> They ran the numbers and tested that placement.  Maintaining the lift
>> ratio between the canard and main wing is paramount and must be
>> maintained to prevent a main wing stall.
>>
>> Scott
>>
>> KMis178813 at aol.com wrote:
>>> Tom
>>>   The factory has a template your looking for. The VG's that you can
>>> get from them come with a template as a kit. The VG's don't cost that
>>> much, knowing were to put them    priceless. Sounds like a Master  card
>>> commercial.
>>>     Ken
>>>
>>> In a message dated 3/27/2009 9:24:59 P.M. Eastern Daylight Time,
>>> tomcat05 at comcast.net writes:
>>>
>>>    Thx Scott--this was the link I forgot to add:
>>>
>>>    http://stolspeed.com/stolspeed-vortex-generators
>>>
>>>    They seem to be better than the factory ones I've seen. If I go  this
>>>    route is there a template available somewhere for a Velocity??   Tom
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