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Why we don't use winglets (DarkAero 1 Wing Design)
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- เผยแพร่เมื่อ 13 ส.ค. 2024
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If you’re interested in aviation, you’ve probably spent enough time looking at airplanes to notice there's a huge variety in the size and shape of airplane wings. Long wings, short wings, folding wings, swept wings…. if you can imagine it, someone's probably already built it and tested it. But why are there so many different wing configurations, and how do engineers come up with all these designs for airplane wings? Let’s look at the wing design for the DarkAero 1 to begin answering these questions.
0:00 - Intro
0:28 - Design Requirements
1:45 - DarkAero 1 Wing Design
2:06 - Lift, Drag, Angle of Attack
2:46 - Lift Equation
6:18 - Stall Characteristics
7:59 - Drag Equation
9:16 - Parasitic Drag
11:42 - Lift Induced Drag & Winglets
13:59 - Summary
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A complete wing design explanation and engineering lesson in less than 15 minutes. Brilliant! Thanks Riley!
I was truly amazed, really brilliant!
Now for the spar and internal wing designs. I'm pulling up my cozy chair.
Your wing design is great.
I will share with you a technique never considered in wing design before.
The technique is called
"Constant lift wing"
With this design, one can never stall another AIRCRAFT .
I will let you and your viewers do the brain storming. Smiles 😁😁🤗
@@balikis ok
I won't let you get any more grey hairs in figuring it out.
As you know, when the rear of the wing is lowered, you get lift and when that envelope of angle is exceeded, one get a stall.
The wing lift concept works in the dame principles as FLAPERONS.
EXCEPT in the wing lift concept works normally on take off snd landing wit or without flaps extension.
But in straight and level flight the entire wing which ha a pivot point in the leading edge, will allow rear of the wing to have a travel of 20 degrees.
When the rear of yhe wing is in the up position, the aircraft should pick up an additional 20 kots in speed, and less fuel consumption because of less drag.
When the rear of the wing is in the down position yhe aircraft will be 20 knots slower. More fuel consumption due to mote drag.
Cessna high wing aircrafts do have a on the ground configuration adjustments.
These aircraft van be adjusted for speed, but will need more runway for take off.
Or
Can be adjusted for load carrying and take off distance will be significantly shorter eith maximum load.
If these adjustments could be made in flight, it would be like having overdrive on your aircraft. 🤗😉🤔😁😀
So, in a nutshell, constant wing lift can convert a standard wing design into a laminal flow wing.
🤔🤔 About it.
@@jetski7611 Rear of wing going up or down is what is technically calld angle of attack
I'm a mechanical engineer who works in a field related to aircraft. I have no formal training in aeronautics and found this explanation of wing design to be one of the best I've ever seen. Well done, and thank you.
Finally, a simple explanation of progressive stall along a wing
If you aren’t an aerospace engineer, how do you know it’s one of the best presentations…
@@TheBrokenFarmer "[...] and found this explanation of wing design to be one of the best *I've ever seen.* [...]"
Also being a mechanical engineer OP likely had this taught in a general aspect, not specialized form as you would if you went for aeronautics specifically, I did in fact have classes about fluid dynamics which involved much of what was shown here and thus can tell it was done very well, reasoning behind choices well explained and just enough told to not be excessive like a class or too superficial like some Tiktok.
@@Kalvinjjthat’s fine. And I didn’t intend my comment to be offensive. I am an aerospace engineer. I can’t remember what I thought about the video. I watched it a while ago. I just thought your comment was kind of amusing.
I am an old fart that loves aviation and greatly admires and respects what you are accomplishing! Your Monday morning engineering explanation of wing design was way over my head but very understandable. You have the unique ability to break very complex engineering concepts into at least relatable concepts. As a former AutoCad instructor myself, teaching adult learners, this is not easy.
Thank you and I look forward to more!
Most impressive part is free handing the perfect airfoils on the white board! Love seeing the progress and detailed explanations!
That was about as thorough of an explanation I have ever seen, on understanding the lift and drag principles behind the design of wing. Excellent video!
What a great concise refresher course.
Being able to rapidly and clearly summarize convoluted technical concepts shows you really know your… stuff. You'd be a top-notch teacher.
(I hope this will make some of the armchair QBs think twice before chiming in with their (generally uninformed) criticisms).
Fantastic job putting all of the calculations into layman's terms! I think that I can speak on behalf of the rest of your viewers, we are anticipating the next episode. Keep up the good work!
that whiteboard layout is totally optimised for the lesson at hand....well done😳
Awesome explanation. Really appreciated the explanation for the absence of winglets, that makes so much sense now.
Great job. I assume you have presented this at your workshops. You were able to lay this out in a very efficient presentation. If your wing design performs as well as this clip you guys are in great shape! Love the content🙂 And the DarkAero. Go DA Go!!
MEng in Aerospace Engineering here. You will not find a better overview of wing design philosophy for people fresh to the topic on the Internet. Expertly broken down and explained
If I were teaching this I’d use Raymer’s book but play this at the start to get everyone aligned before getting into so many details that you can’t see the shape of the forest anymore…
@@Georgewilliamherbert oh for sure. I'll adjust my comment as I really meant a kind of introductory overview as it gets people fresh to the topic familiar with a lot of the important aspects and how they interaft/affect eachtother in a well-presented and easy to understand way.
This is an excellent lecture and a very interesting airplane. Two comments second-order aspects of wing design: First, wing stall characteristics are also important because they couple to the horizontal stabilizer via the downwash field behind the wing. An inboard stall reduces the downwash at the tail, resulting in pitch-down. This softens the stall behavior and causes a lot of stick travel and force before full wing stall. In contrast, a stall at mid semi-span may result in a strengthened downwash at the tail. As the mid-wing starts to stall, the airplane pitches up and the stall can then be very sudden with little stick travel or force. Second point: You note that induced drag can be reduced by increasing aspect ratio. This may or may not be true according to what you hold constant. I find that it a better mental model is that induced drag force is reduced by increasing wingspan. Primary elements of induced drag force are lift (weight), span, and dynamic pressure. Given these, aspect ratio has nothing to do with it. I wish you good progress with the project!
I am a mechanical engineer for farming equipment from Germany.
This content here is pure gold!
Thank you very much!
I've been an airplane nut for 66 years and even worked for Boeing for 22 years (not in design engineering). I've never heard all this explained in one sitting and I must say you did it very succinctly. Thank you for that. Did you select a pretested NACA airfoil or did you do a custom?
I recall them mentioning a NACA 6-series, but my memory could be off. Not sure if that's at root or tip.
@@dudea3378 the so-called „drag bucket“, which is the flattened part at the bottom of the C_D curve, where drag pretty much stays at a constant minimum for a small range of AoA (very beneficial), does indeed suggest a NACA 6-series airfoil, since that’s a pretty distinguishing trait of these high laminar flow airfoils.
he only mentions laminar flow airfoils not a specific NACA series or number
NACA airfoils are from the 70s. There are better tools out there for better airfoil designs.
@@ChrisParayno realy I thought they were 50s at least for the 4 digit series. But yeah there are better airfoils for specific jobs than NACA.
Really really intresting! When I met you guys in the beertent at Oshkosh and you told us about your plans I couldnt believe it but you guys really made progress and you make it understandable aswell!
Phenomenal video, and a world class lesson from Ryley. 11/10. Keep up the amazing work 👍
Best ‘Engineering Explained’ tribute I’ve seen so far :D
Fantastic vid and a concise, cogent explanation of the concepts 👌🏽
My impression is that winglets are about as efficient in drag-reduction as a lengthening of the wingspan by the length of the winglet.
So in principle you use winglets when you have limitations for the wingspan, like for passenger jets at the terminals, or for the 15-meter-limit for gliders.
... or the "two-car garage" limit mentioned in this video. Roll rate is also a consideration.
That's probably the best explanation of the Lift-Drag math in the whole Internet. Thank you, guys, very-very much.
Another way to reduce lift-induced drag is to use a more tapered wing planform. This reduces tip-vortices without requiring an overall high aspect ratio. However, sharply tappered wing planforms aggrivate the tip-stalling tendencies. Good aerodynamic design (to meet desired performance criteria) is all about balancing the various factors to achieve the best result. Nice video, well presented and good explanations of the design choices that were made with the DarkAero.
Very well done! It has been maybe forty some years think I've thought about the basics, Thank for bringing all the basics back to the front of the room. Your quick direct talk covered maybe a week of lectures from the sixties. Well done! The science is really all the same whether flying a Dark Aero 1, F-117, F-35 or a B-787.
You guys are so intelligent and know your stuff, you inspire me as I am a freshman in college and want to become a mechanical engineer soon.
Student engineer and these videos are absolutely fascinating your videos need to be shown to students in the gauntlet to show just how cool engineering is! Super motivating stuff see these videos thanks guys!
Stellar presentation! You've nailed it facilitating engineering discipline of compromise relationships of target performances. As always, I love spending time with you guys... Thank you for sharing...
I'd be very interested to hear about the design decisions you made on the other end of the wing. Dealing with interference drag and the wing intersection with the fuselage is very much an art. There's so many variables at play, the angle of incidence at the root, the fillet radius, the fuselage taper or lack thereof, even the position of the cockpit bubble has an effect.
What a great video. So much information condensed and made simple enough for anyone to grasp. General Aviation is in need of new designs with the latest and greatest technology and you guys are at the forefront. Respect
Keep doing these educational videos ⚡🙏🏻
Thanks! A flashback to my undergrad aero class in the spring of ‘84. That class basically served to convince me that specializing in aerodynamics was not a path I’d be going down🙂 Ya make it seem easy!
I'm an Aeronautical Engineer and there are a lot of things to consider when it comes to Aircraft Design and believe me it's not an easy task to manipulate all those parameters. The way this guy explains it is very much easier than listening to aircraft performance all night long! You'll be able to understand complicated things such as Cl/Cd max and how to compensate for that form drag or also known in the textbooks as "profile drag". Well done, good sir!
PS. I just have one question. With regards to winglets, did split-scimitar winglets ever crossed in DA wing design? Like the one in B737 Max's winglets.
I noticed several moments where it looked like a brother was having some fun, trying to make you lose your focused, professional delivery. You seemed to be fighting a grin… with great determination 😂
We love you guys 😎🎩♠️💙
This is the best concise and clearest video lesson on wing aerodynamics I've seen on TH-cam. Well done!
People of the sky are always pleasant to listen.
Best wishes!
best 15 minutes on aerodynamics i have seen in my life.
Did a design study for retrofitting a small bizjet with winglets as my Master AE thesis. Basically a winglet extends the wing so increases the aspect ratio, just in a different direction, which means you lose some efficiency as the lift vector also changes. So the more you cant (angle) the winglet the more you lose, or to go into a different direction: The best winglet is actually just extending the wing (so 0° can't). Which ties in nicely with this video explanation. You increase AR a little but you do gain parasitic drag. Plus winglet also increases bending moment on the wing, requiring to beef up the structure though there is then an advantage of canting the winglet as it puts the center of lift from the winglet closer to the original wing tip, reducing the bending moment impact compared to a flat wing extension. Not an issue usually though for short GA wings. Last advantage of winglet is keeping wing so span in check if (parking) space requirements need to be considered.
All depends what winglet design you are using. Canting the trailing edge of the winglet slightly inwards towards the fuselage can actually provide an "induced thrust" due to the spanwise flow interacting with oncoming flow and using the winglet like a wing, creating a portion of lift acting inline with the thrust axis. Ideally, the best wings are designed such that you don't need a winglet which is what happened with the 787 after the 737-MAX's winglet process. Currently doing a CFD & wind tunnel analysis of different winglet designs (fenced, scimitar, blended, spiroid) effects and can confirm that it is a "turd polishing" mechanism for poorly designed wings lol.
@@ioanefiso6314 oh yeah, that was basically one notion... Not needing winglets is the best, i.e. extending the wing, though of course at some point bending moments/material strength become and issue taking over.
Your 15 minutes explanation was better than the weeks it took to explain it on the flight academy I went to. It could never interest me. Now I was even wandering what some factors, you didn’t explain, could mean. Looking forward to your next video. Thanks 👍
Nice explanation. It's good practice to design the wing root to stall before the tip, but it's also a matter of how much sooner (in degrees). Even with ailerons in the neutral position, a stall of the left wing root before the right wing root would result in a loss of lift, and an increase in induced drag on the left wing. Gravity would accelerate the airplane downward while slightly yawing and rolling it to the left. At low airspeed, a modest yaw rate and roll rate could increase angle-of-attack enough to stall the entire left wing, out to the tip. With high stall speeds, the angle-of-attack change is smaller.
I loved this video, which was very information-dense without being at all intimidating. Thank you. Another airplane that sometimes has winglets that actually make it SLOWER is the Lancair IV, which needs them at high altitude for yaw stability. A term you didn't mention and pretty much hasn't been mentioned since the 1930s is SPAN LOADING (weight per unit of span length) which is incredibly useful for comparing designs. We talk today about aspect ratio but it allows designs to get too heavy. My old friend Lyle Powell built a heavy 180hp Glasair with two-foot wingtip extensions while my short-wing 150 hp Glasair was built extra light. OUR SPAN LOADINGS WERE IDENTICAL, which bugged the heck out of Lyle as I flew alongside sipping gas.
Would you be able to make a video about why you chose split flaps? By the time air gets to the flaps the top of the wing is no longer laminar flow. So why not use fowler flaps or plain flap?
I found the split flap choice interesting, too; I would be interested in the answer.
Fowler flaps would provide more wing area at low speed than high speed, helping the compromise between high speed drag and stall speed, but presumably were eliminated based on complication.
Everything in one take. That’s amazing!
Great talk, I'd also like to contribute and mention that different airfoils have different levels of longitudinal stability. My very favorite is the tip air foil used on the B-29 bomber, the E220 air foil is a reflex type air foil, its a very fast airfoil but is also very stable. It does require a lot of precision in manufacturing though and is easy two get wrong. You defiantly have a much wider tolerance with the symmetrical NACA foils and they do preform satisfactorily.
After sitting in to a couple of lessons hearing about lift/drag etc. This is by far the best ever.
Thank!
This is great! I wish your video was around when I was graduating HS. It would have made a change in my career path.
This is a great lesson about airfoil design, honestly might send this to some of my student pilots!
Super good explanation of the many criteria of wing design fundamentals. The take away…… compromise is inherent in any wing design.
This took me back 45 years to my engineering course work designing airfoils using Fortran IV and a large room sized IBM 370 main frame. Looking forward to the next episode.
Thank you!
With a trolley loaded up with shoe boxes full of punch cards
@@peterk2455 Yessir!
Amazing aero lesson wasn't expecting this from this video but it was a great explanation!
What a coincidence, I'm studying aerodynamics right now for my CPL and was kind of procrastinating on youtube. Now you're explaining to me what I've been reading the past few days. Thanks a lot!
Would love to hear more about why you chose split flaps.
+1
And I'd really like to see some CFD studies to back that all up. I can help with that if you don't already have it.
I would like to hear the same. In my experience, split flaps add as much drag as lift. I find split flaps generally just add drag and stability in the approach and landing. It’ll be interesting to find if there is a significant difference Vs to Vso.
Excellent video man! Ive always wondered why ALL airplanes dont have winglets because Ive only seen aircrafts benefit from having them. Loved the explanation!
Awesome video. Takes me back to USN Aero Class from 38 years ago. Why split flaps? I did not hear that discussed.
Washout at the tips also serves to reduce the chances of flutter. As a hobby I design, build and fly model aircraft and currently working on a 6 meter glider that at the root has the SD7037 airfoil with 8.28% thickness stroked to Clark-Y at 10.53% thickness at the tips with a washout of 1 degree.
Great video. This is why you only see winglets on airplanes that cruise at low indicated airspeeds where induced drag is significant, mostly jets that fly above 30000 ft. Whitcombe called them "tip sails" originally, because they work like a boat sail close hauled, generating *thrust* from the tip circulation via a lift vector that is inboard and forward, as well as creating an "outwash" (sideways downwash) that weakens the core of the vortice. The effect is like a span increase without increasing bending, and even a little net thrust benefit that is more than the winglet's own parasite drag. But useless on a low altitude airplane, unless you are trying to optimize for climb, or just because they look cool.
a perfect lesson in compromise in design. Super interesting, your wing looks beautiful
That was good. I did not expect the reason for not having winglets to be quite so straightforward.
Love how excited these guys are to geek out over specs.
Wow. Need I say more?
Best explanation of anything ever - prove me wrong in a future episode!
Keep coming, Dark Aero is not only designing a great aircraft, but inducing love for engineering
Thanks. Great level for us techies who are not aerodynamic engineers.
This 1 video has taught me more than 4+ weeks of my Aerospace Engineering Degree. DAMN is this fun, decently informative and prefectly balance. More Power to you guys, keep up the good stuff Subbed!
Fantastic video! Can’t wait for the test flights.
I designed the air foils for the Space Shuttle and all of the SpaceX rockets and for the X-wing Fighter for the Rebels. This is by far the BEST wing design explanation I have ever seen in this galaxy.
And I have oceanfront property in Arizona.
Take a look at the scrappy bush plane. Can take off and land slowly on rough terrain. Much more versatile than a tarmac plane
I remember reading an article that the better finish on a wing surface is actually not a glass smooth - but one that creates a defined boundary layer. The primary reason this was not done on airlines (according to the article) - was the cost to create the surface was very expensive. I will see if I can find the article as I was shocked!
Small groups or individuals have made all the leaps in aviation. Everytime I looked for the missed scientific evidence, you guys addressed my concerns. There was an internet hustler who started taking many thousand dollar down payments from hopefully people. He was a computer guy. His use of bots for positive reviews in comments, production of slick videos ,and attacks on me for pointing things out that couldn't work, were not tested...etc. Since you guys have blended carbon fiber with other metals was my biggest concer
Damn, this is like Engineering Explained for aircraft. I like it!
Please keep doing videos like this. Love it! Thank you.
Onca again, awesome video, can’t wait to see DA1 flying
Such a succinct explanation of so many different principles ... very well done! Hard to find a video that tells you so much in under 15 minutes.
As a non-pilot admirer of aircraft, this was a fantastic presentation that at no point did I feel underwater. Thank you!
What a great presentation! This helps explain how historically, large airplanes started having relatively smaller wings. As flap design progressed, the wings could be that much less of a compromise between cruise and low speed for take-offs and landings. So more elaborate flaps and other high-lift devices allowed wings to be optimized for cruise, so wings started "shrinking" over time for a given airplane size. Unfortunately this won't translate for an airplane as small as this one, since the complexity, weight and drag of intricate high-lift devices would negate their benefit.
Is this guy a professor? He knows everything!
Love this - so a few tangible follow-ups that I'm excited to see flush out in flight testing of the DarkAero 1:
1. What is the cruise speed? (assuming it's the airspeed that correlates to the lowest total drag in the bottom right chart on your whiteboard)
2. What is the stall speed? (ideally the stall speed with full flaps) You guys are smart and safe and I'm sure you are designing for a pretty low stall speed to compete with the microlights coming out of Europe
3. What is the never exceed speed?
TNE is TBD. The other information is right on their website.
They will publish conservative estimates at this point but the real numbers won't be known until flight test is complete.
Best cruise is never at lowest total drag, it's usually to the right (faster than at that point). That would be best endurance.
Thank you for the clarity and logical progression in your explanation
Wow, talk about efficiency... that was an outstanding and crystal-clear explanation of the process. Thank you for this. :-)
Awesome video. I feel smarter for just watching this!
40 years ago I took physics of flight, aerodynamics and advanced aerodynamics as part of my aeronautical science degree. Dr. Ravinga never explained any of the above as well as you did in a 14 minute TH-cam video. Your students are lucky to have you.
Wing Aerodynamics 101 complete.... where do I get my certificate? ;) But seriously, thanks for all the information you share with us. Very neat stuff!
can you put a canopy ( like over the cockpit ) over that light to smooth the shape? Also I originally learned that winglets reduce weight. You basically bent up your wing tip to reduce the leverage on the wing root. For this reason blended winglets are the natural way to do it. Problem is that we are no sensitive on yaw.
Been following the build from the beginning, you guys are putting out great content keep it up ! 🤘🏾
In your “forces” drawing, lift should be perpendicular to the chord line, not the drag vector. I suppose it would be convenient if you could ignore induced drag though :)
I notice the 787 wings are NOT mounted horizonal but at almost 3deg up.
ie, in horizontal flight, there is always trim built in.
So refreshing after watching the infamous Raptor build series.
Absolutely outstanding presentation
Leading edge powered split flaps !
Makes me more into aerospace engineering than i was before. Excellent video!
Nice explainer for summarizing the tradeoffs. Well done
your way of explaining these topics is super awesome and understandable. Great job and wish you the best
I’ve watched every video. I’m really glad you guys decided to video this process.
There goes 45 minutes of my life...
...because you know I am going to have to pour over this AT LEAST 3 times!
🤓😂
Really well done! I've been following you guys for a while and thinking you really had the right idea with this plane from the beginning. I may never be able to afford your plane but this little lesson here will help me build better RC planes. And now I have a little bit better idea why one of my RC planes would drop the wing right before it stalled, I'm so glad to experience that on RC plate instead of the real thing!
Thanks for trip down memory lane of fluid mechanics
This was super interesting and very well explained. Most of the stuff you talked about was new to me, yet the way you explained it made total sense in the end to me. Cheers to you!
The best explanation of wing design fundamentals I’ve seen! Great job breaking down formulae into understandable terms. Keep up the great educational content, you guys are great at it!,
have extendable wings. add some extra length for slow long cruising and landing slowly.
One thing i dont get: At 12:54 you show that the induced drag decreases as an inverse square, which doesnt make any sense, at least according to the formula. The induced component is part of the drag coefficent with is MULTIPLIED by v squared not divided by. So the induced drag also increses by the square. Am I missing something? Or maybe are you accounting for a lower angle of attack at high speeds? But even then, you would not have a reduction of induced drag...
I’d love to see a video like this for the propeller design.
funny that the picture for tip vortecies was an air tractor, i used to work for the company that prodiced all their composite pieces inlcluding the wingtips
Really interesting!! Looking forward to seeing a high speed taxi test, can’t be long now??
You're a great teacher and explainer... loved your presentation