Hangar Flying => Hangar Flying => Topic started by: av-mech on August 13, 2011, 08:38:38 PM
Title: Bill and his fins
Post by: av-mech on August 13, 2011, 08:38:38 PM
Bill,
Do you have any pictures of the trailing MLG wheel fins that I have read about? I came across one of the many excellent articles you have written where you mentioned these as being not much worse than a set of pants.
Title: Re: Bill and his fins
Post by: Bill James on August 14, 2011, 11:27:20 AM
I'll look Arnold. The MLG trailing fins were worth about 8 mph over having nothing but the tires. They were't worth the harassment from the fast guys. I put on a regular set of wheelpants that were worth about 12 mph. Now i have Hertzler's small wheelpants that show about 15 mph benefit. Sam James has those molds now. The nice thing about the trailing pants was that you could stand on the tire. While using his small wheelpants, I think I use slightly larger tires than Hertzler right now. His and Klaus's are the ones to look at.
I once heard of someone putting plastic broom thistle-like filler in the space between the wheelpant hole and tire. Whew. Wonder what percentage of a mph that helped. I still have a few things like that on the list but am glad that i got the simple basic plane in the air 15 years ago. Lots of good flying, earlier. There is plenty of time for those extra things on cold or rainy days once the plane is flying. I started fabricating the trailing pants during the 40 hour restricted period. Like most everyone, i expected to fly that off in 4 days. But on some days, after an hour of flying i was ready to RTB and work on some of the 3rd List things. And maybe catch a sunset run later.
Title: Re: Bill and his fins
Post by: av-mech on August 14, 2011, 12:48:50 PM
Bill,
Thanks for the reply. I was planning on buying a set of pants from Sam James, you say those are the early Hertzler design? I know what your talking about concerning the list of things to do, I have a big one going now. I actually had to put my Vari in another hangar after our return from Osh as it was to distracting to have around and was keeping me from getting customer work done. Once I get caught up though......I have spent a lot of late nights researching and I find it amazing how much aerodynamic efficency is still left to get out of a stock Varieze, pants, cooling, boundry layer stuff etc...... For me this is where the fun is, I really like solving problems and improving perfomance maybe more than simply flying around. I like flying but I think I like problem solving more.
Title: Re: Bill and his fins
Post by: easyrider on August 15, 2011, 01:58:13 PM
If you believe all the stories of speed improvements most Long's and Variz's must be approaching 500kts by now. easyrider
Title: Re: Bill and his fins
Post by: av-mech on August 15, 2011, 05:26:20 PM
easyrider,
I have to laugh.......I was just talking with a friend of mine and I commented that if I were to believe the numbers associated with each common improvement, I would be going 300 mph!! Every common improvement seems to yield between 8 and 12 knots. So with wheel pants and inner fairings, MLG fairings, downdraft cooling, hertzler prop and hershey kiss spinner I have an speed improvement of about 40 to 60 kts!! Not to mention that going faster will unload the prop and allow it to turn faster making more horse power....Look out Klaus I'm coming for ya!!
Title: Re: Bill and his fins
Post by: Bill James on August 16, 2011, 08:07:42 PM
A friend is always after me to know how fast the plane really is. I answer with the latest "on paper" speed. Funny, he is always 30 kts faster than me - on paper :)
Title: Re: Bill and his fins
Post by: Bill James on August 16, 2011, 08:21:11 PM
What i really want to see sometime is how my plane does next to a stock LongEZ at minimum speed. I think that's part of the reasoning behind the LongEZ, to fix the slow flight and landing characteristics of the VariEze. At 4500 feet altitude or so, calm day, cool :) , both planes already checked out for safe, good slow flight characteristics, and just see how a VariEze with vortelons and TE fins compares at minimum speed to a Stock LongEZ at minimum speed. Not maneuvering, just slow flight. Not that it matters, i think we are all pretty happy with our birds, but i wonder if and how much the VariEze improvements over the years have helped it compared to the first flights. Surely lots of you already know how this stacks up. Just one of those things it would be fun to do.
Title: Re: Bill and his fins
Post by: Bill James on August 16, 2011, 08:24:22 PM
Just to be specific, Gary Hertzler mentioned that Sam James now also had his smallest size wheel pant mold, so i am guessing that Sam has at least three sizes of Hertzler-designed EZ heritage pants. Wonder when the next craze in wheel pant design will appear.
Title: Re: Bill and his fins
Post by: go ez on August 17, 2011, 01:50:08 AM
I agree with your thinking Bill
The landing brake and wing improvements have made a significant difference to the Eze at reasonable weights compared to the early fast landing speeds, poor visibility on approach and Dutch roll wing rock that plagued the early days.
Clearly the Long is ultimately capable of carrying significantly more weight than the Eze but a well built clean Eze with more fuel capacity seems to be very capable now. I believe the Eze's higher wing loading makes riding in turbulence more comfortable than the Long. It is smaller and hence (as we get older) more manageable on the ground too.
Ref speed mods - the speed benefit of each mod may well be true but you cannot just linearly add each speed benefit. As the aircraft speed builds up, the actual benefit of a drag reducing mod diminishes such that a mod that (say) on its own gains 5 kts from (say) an original cruise of 140kts to 145kt, whereas if that mod were applied to a cruise speed of 145 kts (due to other mods) may gain only 3 kts to 148 kts :)
Title: Re: Bill and his fins
Post by: Bill James on August 18, 2011, 10:52:03 AM
3 kts? I'll take it! :)
Title: Re: Bill and his fins
Post by: cloudman on August 18, 2011, 10:52:58 AM
What i really want to see sometime is how my plane does next to a stock LongEZ at minimum speed. I think that's part of the reasoning behind the LongEZ, to fix the slow flight and landing characteristics of the VariEze. At 4500 feet altitude or so, calm day, cool :) , both planes already checked out for safe, good slow flight characteristics, and just see how a VariEze with vortelons and TE fins compares at minimum speed to a Stock LongEZ at minimum speed. Not maneuvering, just slow flight. Not that it matters, i think we are all pretty happy with our birds, but i wonder if and how much the VariEze improvements over the years have helped it compared to the first flights. Surely lots of you already know how this stacks up. Just one of those things it would be fun to do.
Bill, In past years with my Varieze I have been interested in lowering my touchdown speed and improving forward visibilty. Originally with wing cuffs, I would experience wing rock around 80 mph indicate on final approach. During this process my forward visibility was gone when getting down to 70 mph at touchdown....so I recall looking to the side to view the runway ! When vortilons replaced the wing cuffs, I noticed better forward visibility along with less wing rock on final. When I replaced the Varieze's lower winglets with LongEz style ones there was considerable improvement with both wing rock and forward visibility. Since I thought I was really on a roll (improvement wise) I added trailing edge fences. Since I could only estimate their sizes, I made them extra large and cut them down in stages. Without the LongEz lower winglets the fences probably would have been effective, but did not seem to make any improvement in what I was after. In fact on takeoff in a good crosswind, without correction the plane would weathevane into the wind and actually head into the wind vs normally climbing straight down the runway. After several years the trailing edge fences are just about gone except for the ones just outboard of the ailerons. I expect that they may provide some extra aileron response. Also, the total combo made my plane really bounce around in rough air....much more than previously. Also, quite a few years ago I made a couple of dozen vortex generators that were temporarily attached to the wings. They have spent more than a dozen years in a jar on my workbench. Just seemed to dirty up the wing too much so I did not really give them a good test. As far as being able to touchdown slowly, I expect that the idle thrust of an engine/propeller combination limits that quite a bit. My effort over the years to lower the touchdown speed has been two-fold. To minimize the energy in case I have to make an off-airport landing and survive....... and to make the first turn-off so I do not have to taxi so far ! Happy flying........ Wayne Johnson Varieze 725EZ.......first flown Corona, CA in 1981
Title: Re: Bill and his fins
Post by: Bill James on August 18, 2011, 08:34:24 PM
Wayne- At Oshkosh this year Klaus told me in no uncertain terms to do the lower winglets, similar to his. He feels it is a safety item. For years I have had the carved foam shapes sitting on the shelf … you know how that is :) I do benefit from the TE Fences, regularly flying approaches ten mph slower, and I believe a similar takeoff benefit. Per your experience with both, starting with the fences already, I may not benefit as much from the lower winglets. We’ll see.
An interesting note, to me anyway, is that with the TE Fences, while the plane is comfortable at ten mph slower approach speed, the nose is actually higher. I watched this with a string attitude indicator on the side windows, without and with the TE Fences. So for my part, the TE fences allow higher attitude on approach, and more comfortable. A side note, immediately after doing the final paint on the plane I flew it once without the six vortelons just to see what the difference was. Never again.
They told me that after years of flying with white primer, going to the new slick paint might have been a slight factor in changing the VariEze’s slow speed characteristics. Unrelated, some said that the plane was faster in the primer and would probably lose some speed with final paint. I think that was during the golf ball dimple craze. Ha. Don’t they know that every mod is worth 2 Kts? Anyway, love those vortelons.
So like you, am always in the hunt for lower touchdown speeds. Moving through similar cycles as you describe, I have designed three flap systems, fun but not worth the effort. One of them is pretty enticing. However, the flap mod would probably ground the plane for a long time, with unknown potential. Looking at it from my perspective, maybe understanding things a little more, the goal moved from slower landing speed, to a lower touchdown nose attitude. I think, but wonder, if the TE Fences would be even better at a slightly lower nose attitude. So much more in the noggin but I will go easy on you and take a break here.
And anyway, in the meantime, adequate landing roll improvement has been made by just getting better at some of that pilot stuff like being set up right for the approach early. Specifically – it helps now to use a little nudge of power just before touchdown to slow the rate of descent. Logic keeps hollering at me that adding power has to increase my touchdown speed, but the experts say that power = altitude and pitch = speed. And that has been my experience. Doing this, with the goal of not raising the nose, the approach speed is slowed. And - when you land and get to the hangar and the brakes are normal, why mess with success? Time for some ginger snaps-
Title: Re: Bill and his fins
Post by: cloudman on August 19, 2011, 12:17:47 PM
Bill, I expect that I would have left the trailing edge fences on ( at least longer for more evaluation ) except for the violent bouncing around I had coming back from Spokane one summer afternoon. I suspect that with the LongEz lower winglets and the fences I had increased the side wind loads on the plane too much. Not being a professional aeronautical engineer type...that is just my guess. Anyhow, I spent an hour trying to climb up high enough to get above the turbulance while keeping the plane upright. Usually, I have tried to fly earlier in the day (or later ) when expecting those conditions and have avoided the really rough air. Happy flying ! Wayne Johnson
Title: Re: Bill and his fins
Post by: Bill James on August 20, 2011, 01:21:35 PM
Wayne, In the same vein as your impression, I do feel that the TE fences are an overall advantage, helping the wing to physically work better at higher AOAs. I appreciate your thoughts and experience. It will be interesting to see what adding the lower winglets does.
We do have to laugh about the performance claims on these planes. But. Two weekend observations come to mind: Arnold, your mentioned averaging about 165 mph, probably representative of many ezes at altitude and at peak or lean of peak. It got my attention at airport breakfast conversations this weekend listening to pilots of other types mention how many fuel stops they had to make on their way home from Osh, and their speeds. Made me feel pretty …blessed? And on the way home from that breakfast, sailing around the south side of Dallas/Fort Worth, hearing Spinks Tower call me out as traffic for a Cessna inbound on the ILS, crossing his path at his one o’clock. The Cessna said something like, “I’ve got him in sight, he’s a fast mover, no problem.” No bragging here. It just is what it is. At cruise I often breathe a sigh of perturbation because the ASI says 165 instead of 250. It helps to figure the TAS :) It would also probably be leveling to make the same flight in my previous Cessna-120 :) If you’re building, like they say, hang in there, do something every day :)
So to my original thought. On landing, I got to work on the landing sequence again. It’s kinda like back when studying leaning, initially being told to just pull the mixture back until it starts to run rough and richen it a little. Then to be thorough, I gathered and read a two-foot stack of material on leaning. After digesting the documented data, now I just pull the mixture back until it starts to run rough. Same with the landings, a lot of preparation and then a simple result. In several conversations over last winter I had mentioned how much I enjoyed the easier landings in the cool temps and dense air, and how that with the coming of summer temps I would have to re-learn how to land in the hot dissipated air. In fact, saddling up for a hot day flight, there are several hot weather “there I was” stories, along with my own experiences, that rise up to remind me to take heed. In particular, I am cautious of and work to avoid low-speed high-bank angles. However, even with record breaking temps here, for some reason this year the landings have been OK. Maybe it is productive to again work through the intricacies of how the plane lands, to separate the event into several layers... Maybe like reviewing the fuel system operation. I guess maybe all that falls into the “Being ahead of the airplane” category.
Title: Re: Bill and his fins
Post by: easyrider on August 20, 2011, 02:58:36 PM
Bill What did Klaus say about the lower winglets, does he mean the plans version? I remember reading a Burt Rutan article on why they are important but I can't remember where it was. I have a standard plans built LongEZ which is slightly heavy, the builder lined the cabin with sound deading material. I have trailing edge fences just outboard od the ailerons, they definately improve low speed handling. I flew for about 3 years without a speed brake and it definately improved my landing technique and a conversion to Grove Wheels and brakes handles the stopping distance. I fitted the electric speed brake after I nearly ran off the end of the runway at Friday Harbor. There is a line of trees on approach which if you are landing flat you have to pull up to miss, the extra height is difficult to loose without a brake. Enjoy your postings Don Denhard LongEZ 93EZ
Title: Re: Bill and his fins
Post by: Bill James on August 20, 2011, 05:06:29 PM
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 :)
Title: Re: Bill and his fins
Post by: LongEZDaveA on August 20, 2011, 08:08:40 PM
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.
Title: Re: Bill and his fins
Post by: easyrider on August 21, 2011, 12:55:23 PM
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
Title: Re: Bill and his fins
Post by: Bill James on August 21, 2011, 03:02:38 PM
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."
Title: Re: Bill and his fins
Post by: BruceS on August 23, 2011, 06:48:36 PM
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.
Title: Re: Bill and his fins
Post by: LongEZDaveA on August 25, 2011, 09:47:46 PM
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.
Title: Re: Bill and his fins
Post by: Bill James on September 02, 2011, 10:20:35 AM
>>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 :)