REFLECTOR: Vortilions and/or VG's?

[Jim Agnew]

Greg,
 
I measured a 23 1/2 degree spanwise flow near my ailerons with the vortalons and VGs.on my 173 Elite.  This was relative to the trailing edge.
 
Jim

Greg Poole <gpoole at zeta.org.au> wrote:

Sure would be interested to see some pictures of tufts on various wing combos at various speeds with / without VGs, Vortilons & lower winglets. Anybody got a camera, some sticky tape and some wool thread?

 

Greg in Sydney


 

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Al Gietzen
Sent: Wednesday, 20 July 2005 10:53 AM
To: 'Velocity Aircraft Owners and Builders list'
Subject: RE: REFLECTOR: Vortilions and/or VG's?

 

 

VGs energize the boundary layer and keep it attached longer and so delay 

the onset of stall. I've never heard of them doing anything measurable 

to inhibit spanwise flow. Vortilons OTOH were put there specifically to 

inhibit spanwise flow and are most active on the lower (high pressure) 

wing surface. I don't know how they delay boundary layer separation 

except as an incidental benefit of reduced spanwise flow.

 

IIRC vortilons and VGs pretty much address different issues ... Jim S.

 

I’ll respectfully disagree on this one.  Tuft testing by the guys here in the San Diego EZ-squadron (on both Vari-EZ and Long-EZ) found that the ONLY span-wise flow that showed up was on the upper surface of the wing, under where the flow had separated at high AOA.  It would begin inboard near the fuselage, and spread outward (and thicken) as AOA increased.  

 

I also recall reading (I don’t know where) that the reason Rutan added the vortilons was to create vortices OVER the wing at high AOA to provide better aileron authority (presumable because it inhibited span-wise flow near the trailing edge which ‘masked’ the ailerons).

 

I think it reasonable to extrapolate that behavior to the Velocity wing.

 

Al

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James F. Agnew
Jim_Agnew_2 at Yahoo.Com
Tampa, FL
Velocity 173 Elite Aircraft Completed & Flying
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