VEZE wing fences

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Offline Barney

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VEZE wing fences
« on: October 20, 2007, 08:14:42 AM »
Ref: http://www.b2streamlines.com/WingFences.pdf

Opinions, suggestions "how to build & attach"?

Thanks,
Barney

Offline Bill James

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VEZE wing fences
« Reply #1 on: October 20, 2007, 09:15:41 AM »
Howdy Barney
Used tow layers BID for the fences. The outside shape was trimmed using parallel straightedges laid on top of and under the wing alongside the fences. So the fences begin just aft of the thickest part of the wing cord. The aft edge of the fence is the depth of the cord. Heard they should extend aft of the wing trailing edge a couple of inches.

For a mounting flange, consider laying up one or two layers BID in place on the protected wing covered with a layer of Peel Ply. After cure, remove from wing. Remove the peel ply and install the flange base with corner tapes. Don't have to stand on your head to do lower flange this way. Replace on the protected wing for cure.

Far as i know there is no published location demension. Equa-distant seems to work fine. Instead of putting one right next to the winglet, I considered the winglet as a 4th fence. Great idea to get perpendicular installation using the string and newspaper technique.
Good flying
Bill James, Fort Worth VariEze N95BJ
Downdraft Plenums, QuickCowls
There was supposed to be anhedral?
ATP, Society of Flight Test Engineers

Offline walter

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Fence Layout
« Reply #2 on: October 20, 2007, 09:52:30 AM »
Try this! Frank P. gets all the credit!

Walter

Offline Bill James

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VEZE wing fences
« Reply #3 on: October 20, 2007, 10:24:20 AM »
Barney,
After perusing the link on your post, it looks like you may be talkng about something i have never seen on an EZ...yet. If so, 'never mind' on my response  :)
Good flying
Bill James, Fort Worth VariEze N95BJ
Downdraft Plenums, QuickCowls
There was supposed to be anhedral?
ATP, Society of Flight Test Engineers

Offline Barney

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Fences
« Reply #4 on: October 20, 2007, 10:25:42 AM »
I have attached one fence similar to Frank P's diagram just outboard of each aileron.  These have proven to be very effective.  This may be a case where a little more (fence) may be even more effective.

From the referenced article:
"Wing fences are generally more effective when they wrap around the
leading edge;" and from observation of the MiG-15 and Falcon 20 which both have full span fences, I'm wondering if more fence on the VEZE might produce an even better result.

I have baggage pods installed which provide somewhat of a fence on the underside of the wing, but from what I understand fences are more efficient on the top of the wing to prevent span-wise airflow from drifting outboard on a swept wing.

Many heads may make light work - keep the suggestions coming.

Offline walter

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VEZE wing fences
« Reply #5 on: October 20, 2007, 10:31:09 AM »
Keep us posted if you pursue it!

Walter

Offline Barney

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VEZE wing fences
« Reply #6 on: October 21, 2007, 06:13:11 PM »
I decided in a fence 2.5" high, full chord to just past the rear edge of the wing, just outside the aileron on top with just a few inches under neath in the front.

I'll try to post a picture here (too much sun in the background)of the template I'm making.

[/img]

Suggestions for material and how to attach the fence?

I'm thinking either aluminum (harder to finish) or a few plies of fiberglass.

The small rear fence was just a piece of aluminum attached with silicone adhesive sealant.

Suggestions to either epoxy or silicone the fence in place?

All suggestions much appreciated.

Barney

Offline Barney

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fences
« Reply #7 on: October 21, 2007, 08:50:02 PM »
Interesting article: spanwise flow & tufting (inhouse, too)

http://www.ez.org/tufting.htm

Offline Bill James

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VEZE wing fences
« Reply #8 on: October 25, 2007, 05:14:57 PM »
Looking through your full wing fence notes some more brings several wonderings to mind.
The proven vortelons and trailing edge fences are certainly effective, each on their own end of the cord. For one thing, you wonder if the full fences as in your picture would be even more effective in taming spanwise flow. Second, you wonder about the net result of the added drag. So many things going on out there!

Three, it has occurred to me that if installed on the wing root or cowl the full fences might also help in directing the air into the prop better.

Forth, if some larger fatter TE fences work better, how about the full fences?

Maybe minus one, at the same time its interesting and prudent to notice that the Ezes have flown with these smooth wings for about thirty years. Success works.

Another wondering is triggered, related to the effects of the wing being in the canard's airflow. The full fences would certainly be somewhat influenced. Again, the net effect would be interesting. Hope you have a sharp eye and pencil.

I once heard that the Eze wings worked better because of the canard's special influence. The value of that comment was worth at least what i paid for it. I think there is a sliver of truth in that pie that would need to be picked out delicately.
Some have raised the canard tips. On the other hand, in the NASA VariEze wind tunnel testing seems i read that they remounted a canard on the lower side of the fuselage and it made little difference.
On my VariEze, visible with yarn, the curved canard tips produce a relatively small three inch vortex back to the wing. Surely that's good, and resulted in at least another 5 extra knots!
Of the various efforts to effect or minimize or recover from the canard flow, they all seem to have worked. Aren't we all smart  :)

Thanks for triggering our interest. Will look forward to hearing about what you learn.
Bill James, Fort Worth VariEze N95BJ
Downdraft Plenums, QuickCowls
There was supposed to be anhedral?
ATP, Society of Flight Test Engineers

Offline Bruce Hughes

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VEZE wing fences
« Reply #9 on: October 26, 2007, 11:41:17 AM »
To all readers/posters:

For some reason this software no longer makes an automatic
return.   The result is some extremely difficult to read email.

PLEASE get into the habit of hitting return after around 60-70
letters.   Otherwise I just cannot take the time to move your
text from side to side to read it.

Maybe your computer does the automatic return.   PLEASE
have mercy on those of us that do not have that feature.

Of course I could just stop reading  ez.org   :(

Thank you for your effort everyone.....

Bruce Hughes  :D
Yelm, WA
Longeze N199BH
retired
taught at Maui Community College

Offline cts

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VEZE wing fences
« Reply #10 on: October 26, 2007, 05:18:13 PM »
Bruce - your software may not be really broken. It could have more to do
with the inclusion of in line pictures in the posting. Since the picture now
makes the browser think that the page is as wide as the pic, it thinks it
has plenty of room before it has to wordwrap.

Walter and Barney could help out by setting the display sizes of their
pictures (if the forum software will accept those html tags) or they could
crop the pictures before including them with an inline post.

Of course, you could always  purchase a wider moniter. A 25 incher could
also double as a TV.  ;-)

(Then again - hitting CRLF every 72 characters or so would ensure that all
of our posts are backward compatable for those of us using laptops
and "older" computers.  But - it is a really hard habbit to get back into
since I threw out the old Corona.)

Offline Jack

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VEZE wing fences
« Reply #11 on: October 27, 2007, 07:02:02 AM »
Quote from: Sonset
Barney,
After perusing the link on your post, it looks like you may be talkng about something i have never seen on an EZ...yet. If so, 'never mind' on my response  :)
Good flying


This goes back a few years when I was out on the West Coast visiting Klaus Savier. He had installed wing fences on his Veri.  Check out his website for further details.  Trust me here, Klaus is a serious speed freak and he added fences for a reason.

I haven't installed any on my Long because have heard they might not do much.  Tis something in the future I might try and damn sure talk to someone with a Long that has installed them.

Jack

Offline flyingwaldo

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Klaus
« Reply #12 on: October 27, 2007, 10:04:27 AM »
Klaus told me they would be a benefit on my Long EZ when I asked him about them at a fly-in.

Offline Bill James

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VEZE wing fences
« Reply #13 on: October 27, 2007, 10:20:01 AM »
Jack-
Hope the full fences work out to be beneficial.
I put the TE fences on the VariEze when they were recommended after flying without them
for about 5 years.
I would certainly agree with the repored benefit on liftoff and approach speed in the VariEze.
They are off being painted right now and there is a difference.

In practice i have noticed how often i am not interested in being in the minimal speed range where
 they have the most effect.

For example, in sporty landing conditions, i have learned to add about ten
 mph to the final approach speed. That learning experience included making a short field landing
just for fun, with a cross wind over trees and buildings. Burble. Should have learned from experience on
that one from someone else's experience  :)
And on a normal takeoff i put the elevator an inch low and let the
nose lift and the plane lift off when it is ready. The climbout speed is comfortable at about 150 mph.
I have noticed that if i pull the nose off 'early' and waddle through the acceleration,
that there is much less energy developed than i like.

I have also talked with folks that almost always do minimum speed takeoffs and landings
and 85 mph climbouts where the fences are of significant benefit.  
And I believe that they are a benefit on approach and climbout
even though i don't always operate the plane at the slow end as much.

After painting the bird i made one flight without the vortelons. That was enough.

Good flying.

Bruce, thanks for the suggestion on returns, was bugging me too but didn't know the
complex solution  :)
Bill James, Fort Worth VariEze N95BJ
Downdraft Plenums, QuickCowls
There was supposed to be anhedral?
ATP, Society of Flight Test Engineers

Offline Jack

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VEZE wing fences
« Reply #14 on: October 29, 2007, 06:18:01 PM »
Quote from: Sonset
J
I have noticed that if i pull the nose off 'early' and waddle through the acceleration,
that there is much less energy developed than i like.

)


I have done more than a few runway flights in the 3 new projects we have built and found it that use full throttle to your magic number and pull it off at idle to find out what happens.  You want that extra energy to blow through stall speed and have a little extra.  I spent 12 years flying in the Navy and was a maintenance check pilot along with a ferry pilot.  In the ferry world we were damn near test pilots because of the junk we had to fly and the numerous problems they could pose.

Main point being, if you have a serious cross wind for takeoff, add some knots and yank it off.  EZs are known to have a somewhat weak nose gear and you want to keep it with the least stress you can.

Landing in a serious crosswind a few tricks are in order.  Add a few knots, look for a building or hangar to block the wind, and once you land put the nose down firmly and keep it there.

My record in my Long was 20 knots at 90 degrees.  In a C-130 it was over 60 knots at 90 degrees and I had condition levers in full reverse and two in the flight range.

To paraphrase an old movie line, "you have to know your limitations".

Drew and I had a discussion on wing fences for Longs.  He wasn't thrilled with them with his Long at the time.  Since I am an old Naval Aviator, flying at min speed for landing is a given.  Added energy in an EZ just adds more rollout and more braking. Recall the old adage of runway behind you doesn't help at all.  Too much speed just adds to wasted runway.  

I have a little time to hit this forum am out of the sandpit for leave. At the moment am hanging my wings up to clear out some room in my garage.

Cheers;

Jack