E-Racer Blended Winglet and Interference Drag CFD Analysis

[@ttystikkrocks1042]

Well that was fun for someone with functionally zero design experience. Thank you for making it accessible and interesting!

[@nicki8731]

As a 15 year old with the attention span of a chicken nugget, I though this video was gonna be boring asf because it's a 600 sub channel and an 18 minute long video. Dude, you did amazing! I sat though the whole thing and enjoyed it! Thank you so much :D If you're wondering why I clicked, I saw a plane with a mustache. How could I resist?

[@Blakearmin]

This comment just made my night! Stay awesome, kid. :)

[@nicki8731]

@@Blakearmin :D

[@maxgood42]

Oh right now I see it , Awesome 🤣🤣 It's a country plane it's not a mustache , it's a BULLBAR.

[@percthirtington4588]

Dude, you put in so much work on your own; I can only imagine how much more awesome the GA community could be with more people like you improving the daily flight experience one step at a time. Amazing work!

[@Triple_J.1]

The reason there is so few brilliant people applying themselves to this area, is because there is little to no money in it. Homebuilders stubbornly refuse to hand over any money for ideas or proven concepts. If you publish a finding in a book, a dozen "experts" will show up touting the benefits as if it was their idea. And other homebuilders will ask for the details without purchasing the book. They will ONLY spend money on physical components or supplies. And Aircraft Spruce is the primary source and beneficiary of half a century of countless thousands of peoples innovation.

[@anthonyb5279]

@@Triple_J.1 This is what I do for a living. People who build RVs and KitFoxes are like that. Reno Racers pay for the good research.... well the ones that run up front do. I have had many RV builders tell me I'm irresponsible for not using a proven design. They quote that universal authority of "They say", I stop them there. I reply, "I AM THEY that say." Then some one quietly tells them I work for NASA. They Go off in a huff because they can't tell me my own business. Then I can complete the talk on CFD for there EAA chapter in peace. There are really only one or 2 of those guys in any EAA chapter. No I don't charge them what I charge Boeing they can't afford that. I just want them to make the best aircraft they can and know it will be safe to fly.

[@Triple_J.1]

@@anthonyb5279excellent! Renos top Unlimited and Sport Gold, and F1 aircraft are some of my favorite designs. Just looking at the details one can learn so much.

[@the.dialogue41]

I work on cars and I have to say I’ve been watching a lot of Aviation channels and this is by far the most detailed video I’ve seen on Aircrafts mainly one’s aerodynamic behaviour. My friend got me into planes and I want to learn how to fly let alone work on planes. This is the channel to grow my knowledge with no doubts.

[@tanguaygt]

I would suggest searching the KZbins for Mike Arnold videos addressing interference drag as well. He has passed but someone is doing a great job of archiving his recordings. In addition to increasing radius, experiment veritical placement in relation to the main wing ie: placement of max thickness of vertical compared to main wing, moving the location of the vertical fore and aft to see results. Try to keep the frontal area constant and see what you get.

[@WalkerWeathers]

Great ideas for future studies. Those Mike Arnold videos are fantastic

[@soconnoriv]

came here to say that! I believe he called 90 degree angles “nozzles”

[@Triple_J.1]

Interference drag is extremely easy to reduce with geometry. Given a known airfoil pressure-distribution, create a junction that does not add significantly to the peak velocity. The pressure distribution of the fuselage side or junction should have a pressure dip aligned with the peak, so the velocity effects do not become additive. Think of it like this: Airflow speeds up over the wing. Airflow also speeds up around the fuselage. Where the two meet, airflow is substantially faster than free stream. Meaning substantially more drag, as that area sees an airflow of a much higher speed than vehicle forward speed.

[@BrianRhodes9763]

@@WalkerWeathers If you need help with SolidWorks give me a shout out. I use SW and CATIA, I may be able to give you a hand.

[@l-vaeronautics2734]

Mike Arnold referenced the text "Fluid Dynamic Drag" by Hoerner. Excellent, excellent read!

[@ibonitog]

Hey great investigation and video! I see that you've kinda struggled with getting good CFD data. I'm a PhD student studying turbulence modelling in CFD and if you're interested we could discuss some of your results and get your CFD game to the next level :) Wish you all the best and continue your awesome work!

[@thorntontarr2894]

Here's hoping he takes you up on your offer as entry level CFD has a low information yield w/r time consumed. However, this video show the author/producer has great good basic skills.

[@anthonyb5279]

You learning COMSOL?

[@RCP-1136]

I was wondering how hish mesh looked like, the periodic nature of some results could indicate a too low resolution.

[@ellmister]

This was really cool to watch. Documenting the whole process from start to finish was really something else. Nice worK!

[@Kralasaurusx]

Wow! The quality and depth in this video is like that of a master's thesis. I can only imagine how much time and effort went into it, but I'm sure the skills you learned along the way will be useful for all sorts of other things down the line. And who knows - it might even save someone's life, knowing to avoid the potential stall situation. Nice work.

[@daveduncan2748]

On the Cessna wing-fuselage intersection (6:26), a small fairing to be attached to the rim of the door between the upper edge of the window and the top of the door. Whether that would be large enough to be significant is still a question. There would also be a small interference near the front edge of the door as it hinges out, but that could be minimized. Given the size of the wing strut fairing and landing gear strut fairing, and the gap between the fuselage and landing gear strut fairing, it seems like a small fillet fairing on the top of the door would still be helpful in reducing drag.

[@taraweathers1606]

Bravo! A very helpful study. I have a new appreciation for how the slightest angle can make a difference. It’s important to do research. Thank you for doing this.!

[@mytech6779]

There are some other side-effect variables to consider.(Grow test-matrix, grow!) The way it appears that you created these curves is to basically cut the corner; which slightly reduces frontal area, it also reduces effective horizontal wing area(similar to the way it reduces effective vertical surface). the other effect is that at high AOA the curve tends to dumps air from the lower surface. Whether these side effects are significant and how they could be compensated through changes in cord and span, is the question of course. I know for a simple winglet, which is not a vertical stabilizer, a simple increase in wingspan is generally more efficient than a winglet of similar frontal area and mass. The exceptions are cases where the bending stress on the wing causes disproportionate added structural mass.(Which is all quite dependent on wing thickness, struts, intended mission, initial aspect ratio, and so on.)

[@KiyoshiKatu]

Fantastic video, keep up the good work. It's super awesome to see that you even had to teach yourself CAD for this. It's always great to see someone go to such lengths to test their knowledge on their own, and even better to see them share those findings with others!

[@gmanvaca8269]

Pretty cool. Wish we knew this in 83 when we built our eze. At that time the straightest build was the fastest due to having the less trim tab factored in to fix crooked builds. We used a builders sight to shoot straight lines and to get the eze as square as possible. 75% we ran at about 190 that was a stock veri eze, no starter, 100hp Lycoming with a prop we bought from Rutan him self. Out of 6 eze’s at the airport ours was the quickest. That radius curve at the winglets would have been interesting.

[@WalkerWeathers]

With the vertical stabilizers moved backwards from the main wing on the Long-EZ, Mark Zeitlin did not believe a curve would be effective in decreasing drag. It would be an interesting test though.

[@anthonyburke5656]

You may think I’m nutz, but I saw winglets on HUGE ceiling fans in the Martin Baker factory at Denver, many years before they appeared on aircraft wings

[@douginorlando6260]

I held a sheet of paper around a fan. It detected airflow. As expected, the fan was blowing air out strongly on the exhaust side(about 60 degrees), but was drawing air in from all other directions (about 300 degrees). The fan would obviously make a poor propeller because it was pulling in some air from the side towards the fan that should have been pushing out air away from the fan. Winglets were an obvious solution way back then before winglets were a thing.

[@kcnmsepognln]

I watched something about the Beechcraft Starship and ended-up here. Even for someone with only a layman's understanding of the subject, I found this very accessible as well as informative. Strong work, thanks!

[@ЕвгенийШевченко-я3б]

Man, you are good, in your standing to get result, even if first long-term tries did not gave you the success.

[@jimgordon7305]

Insightful. Due to Mike Arnold's videos I knew how to decrease interference drag for low wing airplanes. You raise a valuable point for high wing airplanes too.

[@skytrainii8933]

I did this work for the Model 60 Lear Jet. Take a look at the blending on this aircraft vs. the Longhorn wing (model 55 and model 35). There was considerable interference drag on the Longhorn. Not only did we blend the wing into the winglet sail; we controlled the stream-wise pressure distribution by varying the section cord length. The result is what we called the Ogive trailing edge. This matched the wing's center of pressure with the winglet's center of pressure. We gained a whole point of drag reduction doing that.

[@peterbuckton7672]

Or - move the vertical stabiliser backwards about 10 inches, to a foot (ish). Have a look at the current iterations of the wing-foils on the Americas cup yatchs if you dont understand what I mean. This seperates fore/aft the two areas of max interferance between the two foils (vertical and horizontal).

[@Triple_J.1]

This is simply locating the area of minimum pressure on each foil away from each other. So as not to cause an additive acceleration of airflow.

[@maxenielsen]

Very good work!! My work in RF has me running lots of 3D electromagnetic simulations using Ansoft HFSS. Also I run multi-dimensional simulations of circuits using Keysight ADS and Cadence Spectre. So I totally get the trades between accuracy, simulation size, time, and tool capabilities - along with licensing restrictions. Kudos to you for persistence and for developing good insight. I think what happens a lot with running simulations is that one’s biological neural net gets trained. That training, I think, is a primary benefit of using simulators. They may not always provide accurate results. But they will definitely educate your mind about trends. A lot of times this training on trends and principles leads to innovation. Again, great work well explained.

[@operator8014]

Solidworks cfd module has a tool in it to perform analysis across a range of model values. If you build your model so it can update based on table values, you can give the cfd the value that you want to sweep through, it will give you data for all values within the rqnge you specify. It takes FOREVER, but at the end, you can just change the blend radius value and see the updated CFD results without needing to rerun your analysis for each value you want to see. It's also good for finding transition values that you otherwise might miss, as it will focus analysis more on value ranges that show large step changes.

[@tinolino58]

Great findings! Love it! The next step on a ERacer is to eliminate the canard configuration and therefore get a much smaller mainwing.

[@WalkerWeathers]

That would certainly decrease drag, but I'm probably not skilled enough to deal with the other problems that would create

[@mike_oe]

How would that not change the whole stability situation thus requiring a completely new wing design?

[@tinolino58]

@@mike_oe I was joking! Yes canards are inefficient configurations. To much wing surfaces in order to create dynamic stability. Usually they have small cabins and composite surfaces to compensate the drag.

[@volkerracho7257]

Thank you so much for your impressive work on this question! it helped me a lot to understand the aerodynamic issues around winglets better!

[@pctrashtalk2069]

It sounds like a good improvement. One potential problem could be the rudder cable would somehow need to be raised to the new higher lower rudder location or some sort of extension of the rudder horn perhaps on a tube would have to be figured out.

[@WalkerWeathers]

Probably an extra bend in the nylaflow tubing to get the cable to the higher position, but I have not decided yet. Thank you for the suggestions

[@pctrashtalk2069]

@@WalkerWeathers What if you made the outer curve start a bit lower to allow the rudder to be a bit lower? It needs to be flat for the hinges. The rudder cable is in a nylon like tube so it could curve a bit.

[@AwestrikeFearofGods]

I like that you even mentioned "diminishing returns", which are returns, nonetheless. Modern designs like the Boeing 787 wing, seem to indicate that the largest practical radius is optimal. A square has more perimeter than its inscribed circle. Besides reducing interference drag, increasing the winglet radius also reduces frontal area. Less frontal area means less drag. Structurally, it results in less mass, less cost in (composite) material, and the removal of a difficult-to-layup joint.

[@justincase5272]

Outstanding! I've been pushing this for years, ever since working through some computer (Fortran) simulations in the 1980s. We examined winglets whose root chord equaled the wingtip's chord. As for the other parameters: Winglet tip chord: 0% (sharp point) to 200% of winglet root chord Winglet angle relative to horizontal: -120 degrees to 120 degrees Winglet angle of attack relative to winglet root (straight ahead): -30 degrees to +30 degrees Winglet twist relative to winglet angle of attack: -45 degrees to +45 degrees We were exploring extremes and quirks, and really wanted to know what might happen if the winglet were not only canted down, but so much that it was tucked under. Might their be benefits of exploring configurations well outside the boundaries of conventional wisdom, which suggest about a 60 degree angle up and about a 3 degree outward twist? We initially ran it as 1% and 1 degree increments. We quickly realized the PC could not handle 259,200,000 data points! So, we adjusted the increments to 10% and 10 degrees, 25,900 data points, and found no benefits of strange dimensions outside of conventional wisdom. We then re-ran the simulation using 1% and 1 degree increments to +/- 10 units either side of the identified peaks. So, another 160,000 data points. I do not recall the exact final figures, but it's of little consequence as far better simulations and testing have been done since. Besides, we were running this on IBM PCs, the original 4.77 MHz models, and with 640k RAM and 360k floppy drives, no less! I do, however, recall that it was around the following: Winglet tip chord: 42% of winglet root chord Winglet angle relative to horizontal: +47 degrees Winglet angle of attack relative to winglet root: -6 degrees Winglet twist relative to winglet angle of attack: -3 degrees We only explored the reduction in induced drag at POH-published standard-day cruising airspeed at mid-point of a leg of a distance commensurate with normal loading and enough fuel for 80% of MGTOW. Again, we developed the software and equations from earlier published models, so it was more of an exercise in how to conduct simulations than in finding the right answer. Over the years, however, I've been pleasantly surprised to find we were on the right track. I wish we could have have analyzed curved winglets, but we couldn't find any such published equations. Even if we had, it would have required vastly more processing power than we had at our disposal.

[@WalkerWeathers]

That is some fascinating research. Great idea to test all possible configurations just in case some genius design is hiding in a place we wouldn't think to look. I imagine the processing times were painful on such a setup.

[@spondonste]

You might also want to investigate prandtl style wingtips just inboard of the tip and prior to the winglet. This will locally reduce the pressure variance (local to the wingtip) between the upper and lower airfoil surfaces. This tip design could also incorporate winglets with less form drag.

[@RulgertGhostalker]

good work taking it from a suggested radius to showing a law of diminishing returns curve. i am sort of following the DBT Areo development work....that may be introduced as a kit at some point.

[@elighcs4822]

The detached flow you saw at 12 degrees aoa is not necessary a main wing stall. Since it was a small region near the back of the wing, and only a small spanwise section it may have just been local seperation, which the pilot would feel as buffeting.

[@claudiusraphael9423]

Fantastic! Now, - since you had to learn using the software specifically for this purpose - how about a compact tutorial that touches explicitly only basic modelling and setup of simulations?

[@watashiandroid8314]

And thank you for taking the time and effort to make this video and present your research! It has the same vibes as "Think Flight" videos. I really like this type of video. I remember reading or watching something from Mark Zeitlin where he presented his belief that a blended winglet would not appreciably benefit a Cozy since the Cozy already had a good design where the vertical leading edge began aft of the main wing's leading edge. That is possibly something to look into as it would probably be lighter and easier to build.

[@ColinsMarine]

Very interesting. I was wondering if you had also considered a couple other questions. What would happen if you canted the winglets out a small amount but used a smaller radius, I.E. put a 3-4 degree outward can’t but only used a 6” radius. Also in the winglets, if you moved them back slightly, if you look at the winglets of the Long EZ compared to the E-Racer you’ll notice that the Routan winglets actually trail behind the wing (most likely to get them in cleaner air and make the more effective) You’ve done excellent and very thorough analysis, thank you

[@dronepilot260rc]

This is amazing! I flown a flying wing with both wingtip winglets and without and I noticed the winglets caused significant drag

[@WalkerWeathers]

Good to know. I wonder why it does that for a flying wing

[@Native_love]

Wonderful video! Reminds me of the wind tunnel testing before computers - oh how we've grown! Great job buddy! Excellent methodology!

[@Blakearmin]

This was awesome! I appreciate your intrepid masochism in learning that software and the charming quirks you encountered in them.

[@dansmusicuk1]

Very well done. Your time and effort is much appreciated.

[@atatoraman9257]

You can try running the simulation with time steps and iterations. That would let the simulated flow stablize more quickly.

[@sodster68]

Interesting, thanks for sharing! Have you considered investigating the effects of moving the fins back a bit? Having to perpendicular surfaces with increasing pressure, i.e flow passed the thickest point, promotes separation. An example of solving this kind of separation, and associated drag, problem can be seen in designs where the fuselage max width is located aft of the wing. That reduces the need for fillets.

[@n.elliott9122]

Out standing. I believe the canard plane has been attempted in various forms. Even a jet, perhaps. It does seem that for a 4 seater multi composite structure. Supporting a turbine would be doable if, similarly designed like the SF50 in turbine placement and tail design. Your video was spectacular. Please continue to share.

[@999knives]

Great video but Bernoulli Principle 4:57 doesn't explain lift as lift is also produced by flat wings and symmetrical wings

[@kevin-pk6hd]

This is fascinating, I wonder if additional gains can be had with some canard fairings. Also makes me wonder how much a typical 172 has at the root

[@Humble_Electronic_Musician]

Thank you for taking us on our journey and thinking process

[@briankenney4287]

I have a question for you to ponder. I don't need to know your answer but felt I it would be good to mention it. Studies done on winglets by NASA showed that they reduced drag on the wing tips but in doing so they reduced the directional stability of the aircraft because that drag is a stabilizing factor in yaw stability. It was stated in that report that additional vertical surface may be necessary to compensate. Your study is different because the winglets are the vertical surfaces and there is not another vertical surface to help with yaw stability. That may make your case even more critical (or not). So my question is; Have you considered the effects of the modification you are proposing to make on the airplanes yaw stability?

[@ammerudgrenda]

This may not be an issue on a canard airplane since the vertical surface is located aft of the aircraft cg. On a conventional airplane, the vertical surface (winglet) ahead of the cg would definitely be destabilizing in yaw.

[@briankenney4287]

@@ammerudgrenda Well i am glad you answered as your response kind of confirms that you haven't considered it.

[@THarSul]

i wonder if the larger leading radius would work better if you were using a conical curve instead of a cylindrical curve, so that it tapers to a point at the trailing edge, giving you more vertical real estate for the vertical stabilizer. would be a harder shape to fabricate, but i would imagine it has better performance on paper.

[@spartan3299]

On the Cessna, could a faring be placed on the door?

[@WalkerWeathers]

In theory? Yes. In practice? Probably not. Cessnas are frequently flown by student pilots and heavily abused. A door fairing would not survive long in that environment

[@HelpOrNot]

A fatal accident is reported to have been caused by flutter in a blended wing/stabiliser design. I was talking to an ez builder about your video and he told me that blended wing/stabilisers become very sensitive to flutter due to the decreased stiffness of the wing/stabiliser interface. He told me there was a fatal accident caused by this in a long-ez. I've asked him to share a report about the incident and will share it here if he is able to find it. You can easily test the inherent difference in stiffness with a folded paper model

[@thomascharlton8545]

Seems like loss of rudder area could be mitigated to some extent by using a longer rudder chord length?

[@WalkerWeathers]

A small change to the chord length could certainly be effective, but too much would compromise the structural integrity of the vertical stabilizer. It does not have an internal structural member; instead, the outer skin takes all the structural loads

[@kyivstarnet7806]

Wow, so much work done by yourself, and resulted in success! I admire you!

[@Londubh]

16:50 If the problem with increasing the radius is the loss of control surfaces, you should test the different lengths of rudder for a specific radius. For example, if you feel that a 12" radius starts to compromise the control surface too much, try 12" of radius, but bump the tip of the winglet up 3". Likewise, you could try 15" with +3" and +6" inches of overall winglet height. That would result in the same amount of control surface as with the 9" radius, which, in turn, might allow you to keep (most of) the L/D improvements of the larger radius, without compromising handling.

[@whatsthepointanymore]

Higher airspeeds may require more structure be added to wing root. More speed = more lift = more stress. The Velocity XL is my dream plane.

[@cabdouch]

Evidently, Van's has studied "Wing-Root" fairings to add a curve. They found that it actually caused more parasitic drag. Perhaps because the air over the fuselage starts well before the wing, that it is less important there. Awesome work on the wingtip though. On my Cessna T210, I have a STOL Leading Edge Cuff that also came with Down-Turned Winglets. So after viewing your video, I wondered if upward or downward would matter. Given that there is higher pressure below the wing, I would think that downward turning would be better (given ground clearance. It appears that studies to confirm that downward turning works better than upwards turning concerning parasitic drag only Great work, fascinating video

[@johnelliott4521]

See your point on curture, decreasing cotol efficiency, but icreasing height of winglet should correct for that. Grat job, hate to think of the effort you put in.

[@AndyRRR0791]

Nice work. There's still lots left on the table. The AoA of the winglet can be set to provide some net thrust because the induced flow at the winglet is no longer axial and so can provide enough of an angle to generate a lift vector that tilts forward enough to be useful. This is a pretty crap explanation but might help give you the idea. Also, you may find that a panel code such as is available in something like Aeolus or XFLR5 might be more useful for doing the bones of this type of analysis since it is much less computationally intensive and thus you can iterate many more times. Good luck with your investigations!

[@weshull1494]

Great video. Very easy to follow, even for a layman such as myself.

[@friedtomatoes4946]

It's when looking at these tools that I'm happy I used to work with converge science. It has adaptive resolution for simulation. So an areas with low compressibility and interest it only simulates it something like two to three inches whereas areas of interest it can simulate with resolutions finer than millimeters. It also has the ability to do moving surfaces. Requires a supercomputer to run and an expensive license but boy is it powerful. Still takes hours and hours to set up a run only for it to maybe fail halfway through but when it works it's amazing

[@daszieher]

4:44 you might discover that lift does not wor the way you think it does: By "slicing" through the air, the wing accelerates the air downward actually using both surfaces of the wing. The acceleration of air "particles" along the flight path over the top surface of the wing is only a result of the general downward acceleration. From a static frame of reference the wing even accelerates the air forward due to the friction you mention. In the end, the idea derived from Bernoulli's principle that a wing creates lift from "underpressure" above its surface by accelerating the air above it against the direction of flight will not yield nearly enough lifting force. Wind channel observations do not necessarily provide all insight necessary to understand the total balance of (kinetic and pressure) energy states of the air surrounding the wing. 😊

[@rowerwet]

So why don't H and V stabs have small winglets the way the wing does? Seems like there could be an efficiency gain there...

[@PatHaskell]

Couldn’t you make the fairing part of the outside door top?

[@NotSean269]

@walker Weathers damn man! Killed it on this, was wondering what if you put the rear canard on the top so almost like a cesna canard thing, give everyone epic views but could also add a while cargo area at the rear under where the engine could go. and do the winglets work in reverse so have them pointing down since the wing is now much higher?

[@taiming71]

Very interesting video. The big question is how to get it pasted by the FAA and ensuring it is strong enough.

[@bobjoatmon1993]

All the homebuilt aircraft like this are classified 'Experimental' and not type certified by the FAA. They may advise and assist you but the aircraft isn't licensed as a production aircraft so you don't have to have a licensed A&P, you ARE, as builder your own maintenance mechanic. It does make it a bit more complicated to sell the aircraft on to another person. By owning and flying a homebuilt aircraft you are assuming most of your own risk and liability

[@sysfx]

Wondering about a parabolic winglet curve, i.e. from 12" radius to 6" radius. It makes the ratio (local radius/local airfoil span) less variable.

[@WalkerWeathers]

That is a really good idea

[@sysfx]

@@WalkerWeathers negative dihedral angle reduces the curve's length. Something else to play.

[@alaintonatihulopezcaillas2368]

This is April of 2023 and I have seen the video just today, I know it's been months from your post, but I think I can help a little. Your vertical winglets are intended to keep drag reduced, give stability and tilt the aircraft, right? But there's a close up where it seems the profile cut to be a little flatten outboard and a little bumpy inboard, so it looks like having a few lift inboard and crossed lift up with the wing. My proposal to improve your work is to use a symmetrical NACA profile at the winglets. This way, you don't fight lateral lifting at any circumstances. I know you did this almost a year ago... But I believe this might be helpful. Thanks for reading. Greetings!

[@alaintonatihulopezcaillas2368]

Oh yeah! By the minute 05:30 you can see what I saw. There's the lifting profile at the winglets causing the crossed lift. There is where I'd put a NACA 00 profile (just the strength, not the wind force) Great job, BTW!!!

[@Oatmealism]

Wonder if you could run similar tests but to a boxed wing to see if there are any benefits to making a boxed wing aircraft

[@edcew8236]

Fascinating! But the Bearcat has no wing root fairings... is that similar?

[@Triple_J.1]

Wow, lots of work! Reducing the interference drag by blending the intersection to a generous radius is well proven in several blended winglet studies. Hoerner also deals with the subject empirically, if you consider the wing and winglet to be two struts. What would be interesting and arguably more useful to other builders is a structural analysis on the new winglet, and determine what radius is acceptable from a builders perspective. And how the new spar would be constructed.

[@jamesringler987]

Who is hoerner

[@Triple_J.1]

@@jamesringler987 Google: "Hoerner Drag".

[@OtherTheDave]

Serious question here… why not make the internal radius as big as you want and just make the vertical stabilizer taller to compensate for height that’s lost to the curve. There’d be more surface drag, but you’d also decrease the drag from the joint.

[@WalkerWeathers]

The reason I chose not to go with this route is rudder deflection inducing roll. The higher the vertical stabilizers, the more roll they make in addition to yaw when rudders are used.

[@OtherTheDave]

@@WalkerWeathers Ah, ok, thanks!

[@MrJay_White]

what about building the curve into the wing, having it curve down before coming back up into the stabiliser?

[@Jagdtyger2A]

The fairing on the Cessna could just as easily ave been part of the door if they truly wanted to get rid of interference drag at that point of the fuselage/wing junction

[@frictionhitch]

I wonder what results you would get with fences added to the underside of the wing. Perhaps the stall is partially due to vacuum created by the air on the underside running spanways toward the wing tips? Just a thought. People report better performance with the fences so maybe you should rerun your wing with them.

[@jeffandreson]

On the 172 could a curved lip at the top of the door help the airflow between the wing and slab door while still allowing the door to open?

[@Sharft6]

at 1:34 there are some small winglets pointing straight down below the main wing. I remember reading somewhere that some builders omit these which can have some serious safety concerns in specific scenarios but I forget which. Anyway assuming he lower winglet is necessary, I wonder what the best bends would be for each, one curvy, the other straight? or both curvy? or both straight?

[@alanbradbury2829]

Hi, very interesting and helpful. What do you think or a wingtip root mounted propeller, mainly in the pusher configuration? Do you think this can reduce vortices? I understand that this is not able to provide a rudder effect but I am considering drone designs where the effect of a rudder comes from vectoring fans, these may even be on the wing tip. I am hoping that pusher configuration has the same effect as a puller configuration at reducing vortices but with laminar flow wing. In thinking about your design, I wonder if suction within the wing via a very slender fan and holes to suck boundary layer off could also eliminate interference drag at the winglet root.

[@WalkerWeathers]

When you asked this I immediately thought of Think Flight and RC Test Flight. They do videos like this and I found one that somewhat answers this exact question. kzbin.info/www/bejne/jJqcd6R_dqxjiMksi=ojulLXlNsmQ6u1S5 Based on that, I think you get benefits of tip mounted props even in the pusher configuration. They are small benefits, but drag reductions nonetheless. Having some kind of active suction to reduce pressure increases at the joint is an interesting idea. Unfortunately it is too much for most CFD tools as you have to choose between an internal or external analysis. Such a test would involve both. I’m sure there is a way to do it, but I think practical testing on drones would be the best way. Another thing to consider is would the fans draw more power and therefore consume more fuel than a more efficient winglet intersection? These are fascinating questions to think on. I wish I could give a better answer than more questions.

[@MikeNugget]

You can try cloud GPU services for complex calculations, i.e. AWS NISP instance.

[@nterry894100]

Don’t know where you would put your fuel tanks in this plane, but if not in the wings, try a parallel curve on the bottom side of your chord and see what happens to lift. Reason is that it is not Bernoulli, but Coanda and Newton that better explain the reasons for flight.

[@joshieeee20]

Now I've never used these CFD programs or any others but what I'm assuming is the simulation area bounding box looks a bit large, but remember ive never done CFD just generally interested in this sort of thing.

[@WalkerWeathers]

The larger the bounding box, the more realistic the simulation, but a larger box also requires more processing power. I followed some recommendations I found online related to the wing span of the aircraft and my computer fortunately had enough processing power to handle the size.

[@joshieeee20]

​@@WalkerWeathers I figured youd need some extra space i just didnt think it was that much, but whoever made the reccomadations probably knows more than both of us so ill take their word till i find something suggesting otherwise, thanks for the quick reply!

[@UndulatingOlive]

Would it be daft to have a scoop in the high pressure corner of the winglet that could be directed internally of the wing to another portion of the wing and dispersed, say under the wing?

[@WalkerWeathers]

I do not think that is a bad question. It’s honestly a good thought that has me curious. Sadly such a test involves fluids flowing both outside and inside the object, which is beyond the capabilities of the CFD tools I have access to. They can only do an internal or external analysis, but not both at the same time. We might need actual wind tunnel tests to answer the question. Do some research on the Bugatti Model 100 aircraft. It used something like what you suggested for engine cooling and drag reduction.

[@UndulatingOlive]

@Walker Weathers The 100 is where I got the idea from As well as other various racing tech I just don't have the means to build and test aircraft at the moment, though even a model RC version should see benefits

[@WalkerWeathers]

@@UndulatingOlive my email should be in the description. If you want to try some wind-tunnel tests in the future, I would be willing to work with you

[@UndulatingOlive]

@@WalkerWeathers Appreciated, though I've no experience in the maker world, let alone aircraft creation and RC, but I do enjoy the theoretical side of it all, and I get satisfaction vicariously through watching others experiment Maybe one day I'll invest in the practical side

[@markplain2555]

Huh. I have a glider and retro fitted winglets. Drag is everything to us. I don't have to worry about vertical stabilizer (I still have a rudder). I'm probably going to review the angle blending my wing to the winglet. Thanks.

[@jsheridan9110]

Clear, Concise and professional. Good Job.👍

[@randybentley2633]

A point of pondering. In a box wing configuration where the verticle connecting Winget is also acting as a rudder, would both the upper and lower connection points benefit from a curve, or just the lower one?

[@delschier1419]

Great work and interesting! I don't think I am going to blend the winglets on my Cozy IV, it is fast enough :). I understand how much work that must have been. I tried to model a reverse scoop for my oil cooler use a freeware 2D CFD program. Gave up and just made a cardboard one and flew. My son did his senior engineering with CFD modeling. He had to design a cooler for a nuclear reactor. He had to use the schools super computer to do the model in a reasonable time without errors.

[@watashiandroid8314]

I remember seeing something from Mark Zeitlin where he presented that the Cozy already had a good design where the winglet is set aft of the main wing's leading edge and that a blended winglet would not appreciably benefit a Cozy.

[@shark3D]

what about a curve which isnt equally cutting into the stabilizer vs the wing? (starts with a light curve of the wing sharpening as it approaches the stabilizer)

[@GreenGj-]

Its like a long EZ, but faster. My experience with a long EZ left a good impression, and it is a really nice and responsive plane

[@wewillrockyou1986]

Very good investigation. One thing I wonder is if you would have run those 12 degree simulations at a lower airspeed whether the flow would not have separated. 12 degrees AoA at the cruise speed would be a very high wing loading, not realistic for most stall situations which occur close to 1g at normal aircraft weight.

[@windwardpro]

Very interesting. But in your description of lift from a wing, why did you not mention flow turning?

[@borgheses]

what does serrations on the trailing edge of the stabilizer do to the CFD, and if the serrations are vibrated, what happens? at what frequency does the vibration speed match the airflow, and how could you calculate the vibration speed and mode to shed vortices?

[@borgheses]

think of the piezo electric fans, then make them microscopic. just needs to be a vortex generator on a microscopic scale across the trailing edges.

[@Nando-gc8kb]

Hey, I saw the mesh you generated for your CFD simulations. Small problem with it, you didn't add any inflation layers (aka prism layers) to capture boundary layer behavior more accurately.

[@SiliconRiot]

Couldn't you make a longer winglet to add more rudder or design the rudder to hang off the back of the winlet so the blended area doesn't affect it...?

[@MarkShinnick]

Beautiful work, thanks bunches:)

[@lelievre12]

Wow a really great video. I actually have an SQ2000 which originally had E-Racer style wings. I have since changed these for hand layup blended winglets built by Jack Morrison himself. I think they are the 9" radius. They were not only much lighter, but will have the drag improvements you report as well. Am looking forward to the finished aircraft. For photos and details feel free to PM me.

[@aviator267]

This man understands

[@feedingravens]

My God, I was already interested in planes when the VariEze was still new - such videos show me how old I am. I have seen a few numbers about winglets, and from what I seem the rise in efficiency the winglet brings is about the same when you would lengthen the wing by the length of the winglet, i.e. increase the aspect ratio. So that would be the better road to go, lengthen the wing. But many planes have other restrictions regarding wing length, and then the winglet is the right choice. Like on a passenger jet where the place (= width) on the airport terminal is restricted, or when you have a restriction like the 15 Meter-glider class.

[@thorntontarr2894]

Outstanding work presented, well done. A comment from ibonito seems to offer access to more powerful CFD which will improve your results which you clearly understand. If this is your master's thesis, I "grant" you that degree with high distinction.

[@Alumni6042]

Do you think that you're findings would apply to a blended winglet? I've noticed on the blended winglet that the upper winglet has a sharper (lower number) angle than the lower winglet. I ask, because I want to build composite wings for an RV-6, and incorporate a blended winglet. I would appreciate any input that you might have.

[@c_schelli96]

Thank you for putting so much work into this project, I found it very interesting!

[@azertyQ]

not an airplane designer... but could the smaller vertical stabilizer issue be fixed by switching from only having the trailing section of the stabilizer actuate to having the whole surface rotate? (IIRC the f16 uses this for its horizontal tail sections (but for different reasons ??))?

[@GoCreateSomething]

So, why not keep the entire height of the vertical winglets and add a separate curved section between the wing and winglet? Wouldn't that maintain the same amount of rudder authority? Then you could use any curve you wanted.

[@Exaris79]

The design is actually the successor to Japan's WWII Mitsubishi Zero fighter called the Shinzen. The Shinzen prototype design which initially had an aft push prop but next version was with a primitive jet engine or rocket.

[@larsmurdochkalsta8808]

That 12° AOA separation is interesting. Has anyone done active vortex generators for low speed flying? Or is that just generally not a thing? Also, I would be super fascinated to see a blended endplate or blended dual winglet version of this. I really need to get a laptop good enough to start doing CAD lol

[@parrotraiser6541]

If you have access to an aircraft, some tuft tests might help validate ot correct the calculations. (Reality aways has the last word.)

[@GimbleOnDew]

Love your use of Kerbal Space Program