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Votex Generators
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gdh(at)isp.com
Guest

Posted: Wed May 09, 2007 3:38 pm Post subject: Votex Generators

All,

 Has anyone installed Vortex Generators on their  Europa Aircraft??  If not, why not?  If you have, would you please  share your findings?

 Thank you very  much.

 Dale Hetrick

 Europa XS, Tri-Gear, Jabiru

 80 hours

   [quote][b]

ptiller(at)lolacars.com
Guest

Posted: Thu May 10, 2007 12:20 am Post subject: Votex Generators

Hi,



Why would you install vortex generators on a Europa?  VG's are an aerodynamic fix to help when you've got it wrong (i.e flow separations ahead of ailerons etc).  From what I've read, Don Dykins got it right and I can't see a need for adding anything else (other than decent wing/fuse seals that have been discussed earlier).



Phil

Visit -  www.EuropaOwners.org

rampil

Joined: 04 May 2007
Posts: 870

Posted: Thu May 10, 2007 7:22 am Post subject: Re: Votex Generators

VGs are most appropriate for non-laminar flow wings to induce more

laminar-type flow.  Unless you have a really crappy fill and paint job,

vgs won't help a europa much.  Phil is right, read a copy of Dykin's

book on the Europa wing.

_________________
Ira N224XS

fklein(at)orcasonline.com
Guest

Posted: Thu May 10, 2007 9:43 am Post subject: Votex Generators

On Thursday, May 10, 2007, at 01:20  AM, flyingphil2 wrote:



 	  Quote: 	
		    From what I've read, Don Dykins got it right...


	


..with the possible exception of fuselage/wing interference drag...IMO 

most probably the present configuration suffers due to a concern 

regarding kit component manufacturing and trailering considerations in 

that a generous fillet/fairing is sadly missing...



Fred



do not archive

ami(at)mcfadyean.freeserv
Guest

Posted: Thu May 10, 2007 12:57 pm Post subject: Votex Generators

Essential to getting a reasonable and  consistent amount of air through my (rather small) cockpit NACA vents!  (which are located in the "standard" position).

  

 Do NACA vents have a critical Re above which they  don't work well?

  

 I have a suspicion that a VG ahead of the  NACA on top of the cowl may be beneficial too, as this vent seems to stall at  high AoA (i.e. when pulling in to the climb without change of airspeed the WoT  revs are not maintained meaning (on mine) that hot under cowl air is being  consumed, rather than cool air from outside).

  

 Need to find out for sure.

  

 Duncan McF.

 [quote]   ---

grahamsingleton(at)btinte
Guest

Posted: Thu May 10, 2007 1:39 pm Post subject: Votex Generators

Ira

VGs were applied to the wing and canard of a Long EZ, which has laminar 

sections on both, to reduce stall speed, the VGs re energise the laminar 

boundary layer and help to prevent separation after the max thickness 

point of the section. Stall was reduced by 7 kts.

Graham



rampil wrote:

 	  Quote: 	
		   

 

 VGs are most appropriate for non-laminar flow wings to induce more

 laminar-type flow.  Unless you have a really crappy fill and paint job,

 vgs won't help a europa much.  Phil is right, read a copy of Dykin's

 book on the Europa wing.

 

 --------

 Ira N224XS

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=112028#112028

 

 

 

 

 

 

 

 

 

 

 


	


-- 

Graham Singleton



Tel: +441629820187

Mob: +447739582005

fklein(at)orcasonline.com
Guest

Posted: Thu May 10, 2007 4:56 pm Post subject: Votex Generators

On Thursday, May 10, 2007, at 02:41  PM, Graham Singleton wrote:



 	  Quote: 	
		   VGs were applied to the wing and canard of a Long EZ, which has 

 laminar sections on both, to reduce stall speed, the VGs re energise 

 the laminar boundary layer and help to prevent separation after the 

 max thickness point of the section. Stall was reduced by 7 kts.

 Graham


	


	So here's a question...



Is it conceivable that adding VGs to the Europa could reduce the stall 

speed sufficiently to meet the LSA requirements?

gdh(at)isp.com
Guest

Posted: Thu May 10, 2007 5:13 pm Post subject: Votex Generators

Duncan,

 It would be worth trying.  It should only  require a few VG's.

 Dale

 [quote]   ---

gdh(at)isp.com
Guest

Posted: Thu May 10, 2007 5:15 pm Post subject: Votex Generators

Graham,

My goal is to reduce the stall speeds sufficiently to "maybe" qualify for 

the LSA designation.  Having slower approach speeds would be a big plus as 

well.

Dale

---

gdh(at)isp.com
Guest

Posted: Thu May 10, 2007 5:18 pm Post subject: Votex Generators

Fred,

I.m told that the VG's can ruduce the stall speeds by as much as 12 mph, 

aircraft dependable of course.

I'm thinking seriously of giving it a try.

Dale

---

keithhickling(at)clear.ne
Guest

Posted: Thu May 10, 2007 11:43 pm Post subject: Votex Generators

Do they increase drag at higher speeds?



Keith Hickling.



---

ptiller(at)lolacars.com
Guest

Posted: Fri May 11, 2007 1:34 am Post subject: Votex Generators

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

Visit -  www.EuropaOwners.org

fklein(at)orcasonline.com
Guest

Posted: Fri May 11, 2007 7:12 am Post subject: Votex Generators

Phil,



The resourceful minds plugged into this forum never cease to amaze 

me...thanks for sharing your knowledge of VGs.



Would you care to opine as to the aerodynamics of the 

wingroot/flap/fuselage intersection and what might be done to reduce 

drag in this area?



Fred

A194



On Friday, May 11, 2007, at 02:33  AM, flyingphil2 wrote:



 	  Quote: 	
		   



 I'm an aerodynamicist by trade and so here's my answers to the points 

 above:

gdh(at)isp.com
Guest

Posted: Fri May 11, 2007 7:21 am Post subject: Votex Generators

Keith,

Not according to their information.

Dale

---

gdh(at)isp.com
Guest

Posted: Fri May 11, 2007 7:34 am Post subject: Votex Generators

Phil,

Thank you very much for your insight on VG's.  Guess I had better wait until 

after you run your simulations before adding them.

Thanks again,

Dale

---

ptiller(at)lolacars.com
Guest

Posted: Fri May 11, 2007 8:15 am Post subject: Votex Generators

Hi Fred,



Well my thoughts on this would be as follows:



1.  Is there a problem in that area?  Oil flow tests would show up any separations in that area or maybe someone with a dirty aircraft has flown through rain and has some pictures of the surface flow patterns that were left.  If there is no obvious problem then I'd leave it alone.



2.  If there is a problem then making a really good job of the wing fillets would be the best approach and maybe trying to maximise the radius of that fillet (larger radius = better).  The problem with a large radius is what happens when you come to the trailing edge of the wing (or in the Europa's case, where the wing ends and the flap starts).  You need to lose that large radius and run it out to nothing smoothly.



3.  Sealing the wing against the fuselage would definitely be good.  On gliders, we use PVC tape but that only works if you have a small 'wing stub' moulded into the fuselage that the wing butts up to.  On a Europa I would say that some high density foam on the inside of the wing root fillet would do the trick and when the wings are fitted, the foam is compressed and thus forms a nice seal.  I.m not sure what gaps people have between the fuselage and the wing fillets but try and keep them as small as possible.



In terms of drag reduction I would have thought that there is little to do on the Europa.  It's already an excellent design and the use of composite materials (and ability to build almost any shape) helps this.  Compared to some homebuilts on the market using the same engine, it has to be a very efficient machine.  Having said that, you notice the difference on a glider if the wing roots are not taped and the controls are not sealed and so all these little bits of attention to detail would add up and help reduce the drag that little bit further.



Actually, that's an interesting point above.  Out of all the homebuilts powered with a 912S, there can't be many aircraft that are faster than a Europa.  There is the DynAero MCR1 (which I had an amazing flight in once) and that is very fast but look at the size of it - it's tiny.  Anyone have any other comparisons?



Phil

Visit -  www.EuropaOwners.org

rparigor(at)suffolk.lib.n
Guest

Posted: Fri May 11, 2007 8:19 am Post subject: Votex Generators

A few negatives to keep in mind with Vortex generators:



Cleaning = PIA

Waxing = PIA

Painting = PIA



Another thing to break



Ron Parigoris

rampil

Joined: 04 May 2007
Posts: 870

Posted: Fri May 11, 2007 9:40 am Post subject: Re: Votex Generators

Re Conversion to LSA specs



Europa04 and Custom Flight Creations (AKA Europa USA)

currently has Bud Yerly working on a new wing design to meet

the LSA spec and be easier and less expensive.



As I noted previously in the forum, Bud is the only guy I who has a 

degree in ->Low Speed<- Aeronautical Engineering from the US Air 

Force Academy.



Bud's work so far with E04 has enabled the company to reduce the 

kit price by $8k.



The new wing is still in the design phase, so bugging Bud or E04 is not

likely to be fruitful.

_________________
Ira N224XS

grahamsingleton(at)btinte
Guest

Posted: Fri May 11, 2007 9:57 am Post subject: Votex Generators

Phil

the nioest wing root I've seen is Ted and Justin's, small radius at the 

LE, large at the TE. picture attached. imho this is the way to do it, 

the fillet needs to be flexible to allow wing bending without crushing 

the fuselage side, so no more than 3 plies of BID at the edge. There are 

several Europas with this style but only Ted's has the elegant change of 

radius moving aft.

Easier to rig a wing done like this too, something to line up with as it 

goes in.

Graham



flyingphil2 wrote:

 	  Quote: 	
		   

 

 Hi Fred,

 

 Well my thoughts on this would be as follows:

 

 1.  Is there a problem in that area?  Oil flow tests would show up any separations in that area or maybe someone with a dirty aircraft has flown through rain and has some pictures of the surface flow patterns that were left.  If there is no obvious problem then I'd leave it alone.

 

 2.  If there is a problem then making a really good job of the wing fillets would be the best approach and maybe trying to maximise the radius of that fillet (larger radius = better).  The problem with a large radius is what happens when you come to the trailing edge of the wing (or in the Europa's case, where the wing ends and the flap starts).  You need to lose that large radius and run it out to nothing smoothly.

 

 3.  Sealing the wing against the fuselage would definitely be good.  On gliders, we use PVC tape but that only works if you have a small 'wing stub' moulded into the fuselage that the wing butts up to.  On a Europa I would say that some high density foam on the inside of the wing root fillet would do the trick and when the wings are fitted, the foam is compressed and thus forms a nice seal.  I.m not sure what gaps people have between the fuselage and the wing fillets but try and keep them as small as possible.

 

 In terms of drag reduction I would have thought that there is little to do on the Europa.  It's already an excellent design and the use of composite materials (and ability to build almost any shape) helps this.  Compared to some homebuilts on the market using the same engine, it has to be a very efficient machine.  Having said that, you notice the difference on a glider if the wing roots are not taped and the controls are not sealed and so all these little bits of attention to detail would add up and help reduce the drag that little bit further.

 

 Actually, that's an interesting point above.  Out of all the homebuilts powered with a 912S, there can't be many aircraft that are faster than a Europa.  There is the DynAero MCR1 (which I had an amazing flight in once) and that is very fast but look at the size of it - it's tiny.  Anyone have any other comparisons?

 

 Phil

 

 

 

 

 

 

 Visit -  www.EuropaOwners.org

 

 

 

 

 

 

 

 

 


	


-- 

Graham Singleton



Tel: +441629820187

Mob: +447739582005

Ted_Gladstones_wing_root_em.jpg

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karelvranken(at)hotmail.c
Guest

Posted: Fri May 11, 2007 1:09 pm Post subject: Votex Generators

Phil, Graham and all,

In attachment my solution for the wing root drag problem. While building I 

fixed the fairing as well to the wing as to the fuselage and cut it vertical 

with the wing root. Then I reinforced both to become entire part and 

sufficient solid. I also prolonged the upper side at the fuselage to cover 

the gap for the flap torque tube so that no spoiled fuel or water could 

penetrate the fuselage. This solution gave me some advantages:

- the fuselage is certainly reinforced

- the rigging of the wing is easier because you see exactly were the root 

has to meet

- sealing with tape is easy as I did before with my gliders.

Thank you Phil for your much apreciated intervention.

Karel Vranken.

---

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