Bill and his fins

[Bill James]

Don-
On the lower winglets, I believe Klaus feels that they add stability at the slower speeds. We were talking VariEzes, not LongEZs. I asked him how big to make them for my VariEze and he said about the size of his, which are relatively small. I don’t know of anyone else that has worked on this area on the VariEze and I appreciate Klaus’s experience. From what I have heard and understand, the lower winglets make sense on both planes, reducing the flow of the higher pressure air under the wing around up over the wingtip to the lower pressure on top. But the upper winglet already there doing some of that. I guess more is better. Plenty to ponder  
On the LongEZ lower winglets, I did hear a comment by Burt on the ramp at his birthday. We were standing by a LongEZ and someone asked him what he thought about not installing the lower winglet. This one had lower winglets.
My interpretation here!!  -
It seemed to me like it was the first time Burt had thought about not installing the lower winglet. I guess he was thinking about other things a lot       He looked at the winglet for a moment and ran his fingers over outside joint between the winglets (where there are several overlapping plys) and then the inside corner of the lower winglet, and said something like, “Well, I guess you could live without the structural strength of the lower winglet,” and he looked up and down the winglet several times.
I was surprised that he was thinking and answering related to structural strength of the attachment rather than the aerodynamics. First time i had heard someone do that. By the way he gently pushed inward on the upper winglet, I definitely got the impression that both the upper and lower winglet were intended to contribute to the upper winglet not failing inward, a new thought for me. In the moment, I could see how the lower winglet did in fact add significant strength of the upper winglet. While i mention nothing useful here, the response from The Designer changed how I think about how well I understand structural things    
Then Burt said something about Nat Puffer doing some tests that seem to show they are a benefit. Then he said something about plenty of people flying LongEZs without lower winglets. So as to aerodynamic enlightenment, no cigar, but a cautious step back for me.  
Sounds like you approach your landings with appropriate attention. Pun intended. Great fun, huh. Good luck.
We each start out our Eze journeys with such grand advantage. Then we frown at not being privileged at every turn. Shame on us  

[LongEZDaveA]

I built my Long without the lower winglets, so I don't have data to compare on before or after.  So far, I have not added lower winglets (right or wrong) in an effort of drag reduction.  I have found that there is significant upward flow on the bottom of my rudders.  I think that I will be able to reduce drag by adding some variation of lower winglets.  Currently, when the air flows upward on my rudders, it runs into the flat bottom of my rudders.  I believe I will benefit from a small drag reduction when I put "winglets" in place that reduce this drag.

[easyrider]

Bill
Thanks for the feedback on lower winglets.
I was thinking aerodynamically I know mine are structually sound because the builder was at an airshow/Flyin and a LongEZ did a high speed pass and a winglet came off with drastic results.The builder went home and added more layups to the wing winglet junction!
Blue skies and tailwinds.
Don Denhard
Longez 93EZ

[Bill James]

Dave, your LongEZ winglets were generating quite a bit of discussion at Oshkosh, all I heard was good of course, wondering how much of what was going on with the flat bottoms of the rudders was positive and how much of the airflow if any was negative.  It would be interesting to be able to see the air actually moving around there, and somehow measure the benefits. Who is going to come up with a way for us to do that in a garage?  
The key phrase on all this seems to be "attached airflow."

[BruceS]

Would using the gull wing style like Jack Morrison did on his first E-Racer help in drag reduction on the Vari's? If I can recall correctly(which is not so good sometimes), he said he picked up about 12 knots when he changed over to the gull wing style. As for strength of the winglet, he carried the wing spar up through the winglet.

Bruce

[LongEZDaveA]

Bill,

I would have loved to have been a fly on the wall to hear the discussions about my winglets!  I'm sure they are not optimal and that's all I'm sure of.  I hope to improve on them, but that probably won't happen before my Reno trip.

[Bill James]

>>Bruce said, "Would using the gull wing style like Jack Morrison did on his first E-Racer help in drag reduction on the Vari's?"
The general comments I overhear indicate that the wing/winglet intersection is more of an issue when the thickest part of both cords are aligned, or close to aligned.
The undesirable effect is that after the air passes over the highest point of the adjacent cords, there is a negative slope in that inside corner on both winglet and wing surfaces, resulting in separation, that dratted drag, and worst of all… those horrid curly oil flows for everyone to see  
Evidently the closer the max cord heights are, the worse it is.
The VariEze winglet is installed pretty far aft on the wingtip, so the max winglet cord thickness is near the trailing edge of the wing, and the airflow can kinda alternate past them. I believe that the E-Racer intersection design has both max thicknesses very closely aligned, and that the LongEZ and Cozy are in between. One would expect that the E-Racer type attachment could benefit from the blended winglet intersection the most, the VariEze the least. {there was a very interesting glitch here for a while, much better than i usually come up with. Sorry if you missed it   }
I think we are witnessing a learning curve   on the wing/winglet intersection. At some point a significant shape or element will begin to appear at fly-ins. Or not. Would love to hear more-learned opinions...
I have had dramatic success in vanquishing curly oil flows in a particular area.  
…Only to have one of the gurus’ at the next fly-in (still ten feet from the airplane) point to a newly contaminated location around the corner where the air molecules have craftily repositioned and recruited. How could I have not seen that?

       Bruce, that’s what I hear.

I am often reminded of the VariEze at the early-90s KC-GIG with raw foam lower winglets and a weathered raw patch on the nose, and a 2000 hour patch on the headrest