Vortex Generators

Author Topic: Vortex Generators  (Read 26814 times)

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Offline easyrider

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« on: February 23, 2005, 12:01:16 PM »
I know this has been a topic many times.
I am considering putting V.G's on my canard.
I have a LongEZ with a GU canard.
I am considering V.G's instead of the more costly alternative of a Roncz.
What's the trade off?
Easyrider

Offline Dave in Eugene

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« Reply #1 on: February 23, 2005, 03:17:29 PM »
I am installing mine this week. I'd love any advice from those who have done it & I will relay my experiene when I am done.

I told build time on a Roncz is aprox 175-200 hours and some still have slight rain affect.

Love to hear what you learn. Dave
408 EZ Long EZ 0235-L2C / Great American 62X62 / IFR / GU canard

Offline Dj Rise

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« Reply #2 on: February 23, 2005, 04:14:56 PM »
I put them on about two years ago. On my Long with GU canard. I had very little pitch change in rain even before that. With the VG's. I gained no speed. I lost almost 10 mph on landing speed, and gained a lot of Canard athority at lower speeds. No change in trim settings in the rain. I think Waiter has them on his bird also.

Offline Waiter

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« Reply #3 on: February 23, 2005, 05:51:01 PM »
I have the Rontz canard, and no VGs installed.

Waiter
LongEZ-RG   >>    N961EZ
O-320 160hp  >>    MT Constant Speed Prop
F-16 Performance, On a Piper Cub Budget
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Offline Dave in Eugene

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« Reply #4 on: February 23, 2005, 09:59:51 PM »
DJ,

I am interested to hear where you placed your VG's.

From the literature that I got, it is the recomendation to place them on the back 1/3rd of the chord of the canard. From my limited amount of aerodynamic knowlege I would assume that this does nothing to increase lift or slow stall speed.

The article that I read says that lift is decreased in the rain because water sheets from the rear of the canard to the front and disrupts the laminar flow of the air. The aft placed VG's disturb the air so that it doesn't allow for sheeting....makes sense to me.

There are explicet directions not to place the VG's on the leading edge of the canard as it could change the dynamic of the canard stalling 1st which could be very dangerous (deep stall). I have seen pics of VG's nearer to the leading edge of the canard (on an airshow EZ site) made me wonder how the pilot / builder figured out the relationship between the stall speed of the canard and the main wing...

Thanks for your input
408 EZ Long EZ 0235-L2C / Great American 62X62 / IFR / GU canard

Offline Drew

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« Reply #5 on: February 23, 2005, 10:03:35 PM »
I have the GU canard.  The first time I flew into a puffy cloud (I was hands off at the time), the plane went into enough of a nose dive to lift me out of my seat.  My first time I flew IMC in my longez, I would go from full forward trim to full aft trim.  This was really a lot of workload for IMC flight.  I put on the vortex generators and it cured the problem (maybe a very slight trim change----but nothing to get worried about.
Drew Swenson
Cozy N171ML

dj ries

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VG's
« Reply #6 on: February 24, 2005, 10:13:04 AM »
Dave, I don't know about other Long-EZ'z. I was very careful when I instaled my canard after reading CP 35 page 2, 01/1983. In short it said the Long's with the most pitch down in rain was caused by not fitting the Canard per plans. I used a transit to make sure. I guess it worked cause I had little or no pitch down in rain without VG's. I put the VG's on to get more pitch athority at slower landing speeds. They do that. Another thing I changed that I feel helps is the Strong electric pitch trim. It so much better than the per plans system.
In short I can't tell you why they work. They just do. There are drawbacks with VG's. First, you can't sit on the Canard anymore.  You can't keep people from touching them.

Offline easyrider

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« Reply #7 on: February 24, 2005, 11:03:21 AM »
Drew
Thanks for the reply
I am looking to decrease pitch change in rain.
Where did you position the VG's and what type did you use?
Regards
Easyrider

Offline Drew

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« Reply #8 on: February 24, 2005, 04:24:07 PM »
You can get them from: http://www.mywebco.com/cci/
The leading edge goes on the 50% chord.  A template is supplied with the kit that gives you the correct angles.  You can eyeball the 50% chord by looking at the end of the canard and looking for the fatest section of the wing (laminar flow wings usually have the thickest part of the wing at the 50%chord as opposed to the quarter chord).  Mark a spot on the canard where that thickest part is.  Then measure the distance from the elevator "notch"----the back of the canard but not the elevator---to the spot that you marked.  Transfer those dimensions to the inner portion of the canard and to the other side of the canard.  Snap a line and start laying down VGs.  Don't use the glue, too easy for kids (and adults) to pull them off.  VGs are like magnets to fingers.  Everyone wants to pull on them.  People would get really mad at me for fingering their car the way that some finger my plane-----for some odd reason, people think that fingering planes is ok----oh well.  The clear silicone works great---you have to be pretty determined to get one of those off.
Drew Swenson
Cozy N171ML

Offline Daniel Tyrkiel

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« Reply #9 on: February 24, 2005, 09:16:30 PM »
I'm not a builder nor an owner yet, but I found a great aerodynamics site by Martin Hepperle http://www.mh-aerotools.de/airfoils/turbulat.htm
The above link will get you to a nice explanation what turbulators do. It's a model airplane site, but model planes fly the same just with smaller Re numbers  :wink:
Think for Yourself, Question Authority...

dave

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« Reply #10 on: February 27, 2005, 07:13:17 PM »
hello,
   i have GU canard...and i have vortex generators..installed on the wings and the canard...after an encounter with jim price...at my airport ..he was enroute to michigan...,, i got slightly lower take off speeds...no drag...and  much gentler...landings....
   the vg's for rain is a bit diffrnt...in position and amout...

Offline Dave in Eugene

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« Reply #11 on: February 27, 2005, 07:17:29 PM »
DAve can you tell me more about the position and the amount that you used for your vg installation. Also more specifics about affect in rain.

Thanks,

Dave
408 EZ Long EZ 0235-L2C / Great American 62X62 / IFR / GU canard

DAVE

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vg's
« Reply #12 on: February 28, 2005, 12:15:10 AM »
hello dave in eugene,

      the VG's for rain...are installed  After the 50% part of the chord..the backside  ( counting from the leading edge)....they are installed  closer to the outboard  and only 5" apart....angle is 20 degrees...
   ive seen 3-4 per side.......

Offline Dave in Eugene

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« Reply #13 on: February 16, 2006, 11:56:59 PM »
A long time since I posted about this one. I still haven't put on the VG's and I am working up the courage. Can anyone who has installed VG's on the back of the canard comment? I am just a bit nervous.

thanks,

Dave
408 EZ Long EZ 0235-L2C / Great American 62X62 / IFR / GU canard

Offline Drew

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« Reply #14 on: February 17, 2006, 01:41:17 PM »
Nothing to be nervous about.  If your canard is built correctly and the incidence correct---and you are within your CG limits---then you will have no problems.

Put the vgs where the directions say to put them (50% chord).  Use clear silicone.  I have flown my Longez a lot---both before and after vgs----no detrimental effects.  Cured rain problems.
Drew Swenson
Cozy N171ML