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.
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.
@@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!
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!
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!
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!
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.
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.
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.
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!!
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.
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!
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.
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.
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.
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.
Excellent video man! Ive always wondered why ALL airplanes dont have winglets because Ive only seen aircrafts benefit from having them. Loved the explanation!
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.
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...
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
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 😎🎩♠️💙
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!
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.
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.
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!
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?
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!
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.
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!
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!
Thanks! Good review of the basics - but thin on the wingtip design choice factors. Yes, nice intro of induced and parasitic drag all to get to the 30 seconds of punch-line between 13:30 and 14:00. Glossed are factors that let winglets deliver 5-10% less cruise drag for airlines (also operating way out to the right on you drag chart). Additionally, common wingtip designs are not considered (ie hoerner, blended, canted etc). I guess the question the comes to mind is: why squared rather than any of the many tip designs will proven to reduce low angle of attack (cruise) drag?
13:45 with wingtips you reduce the induced drag that is true. But here is the magic part. With wingtips you can "fill" your wing with higher lift coefficient. And you can build a smaller wing or a wing with less aspect ratio. In the end a good airplane is a trade off design. You have structural weight, wingtips add weight, but a smaller wing reduces it. Find the best solution
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!
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 👍
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.
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!
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!
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!,
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.
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 UA-cam video. Your students are lucky to have you.
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.
Just for understanding: Is the plane most efficient at cruise speed or at that lower minimum drag point? I am assuming your engine is optimized for cruise speed. Would an electric one shift the efficiency point of distance per energy down towards that minimum drag point?
Thanks for the great video. Have you considered tapering the tips (keeping the same wingspan)? It should give you a somewhat better climb-rate, without any loss at the top end.
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.
This is really well done. I dont know much about aerodynamics, but I understood almost everything you said. Really great explanation!! Thanks so much!!
The next time your around a Cirrus take a really close look at that wing. They have a different chord/shape and twist. New designs also narrow the fuselage behind the wing, Diamond is a really good example of that. It improves airflow and reduces drag. And I think it's TBM/Mooney that has a twist wing to improve roll control. Just adding a "wiglet" is not always a good thing. Cessna Jet's is an example! JMHO's --gary
Your wing tips are blunt with just 1" radius transition from horizontal to vertical. Is this for ease of building or an aero design for max performance?
*Video Summary: Why we don't use winglets (DarkAero 1 Wing Design)* *Key Points:* - *Design Requirements:* DarkAero 1 aims for high-speed, long-range flight with a stall speed less than 60 knots. The wing should have a progressive stall from root to tip. - *Lift and Drag:* Two fundamental aerodynamic forces. Lift is governed by air density, velocity, wing area, and lift coefficient. Drag is similar but focuses on drag coefficient. - *Trade-offs:* High-speed cruise conflicts with low stall speed. The wing design is an iterative process to balance these conflicting requirements. - *Stall Behavior:* A progressive stall is desired, starting at the root and moving towards the tip. Different airfoils are used at the root and tip to achieve this. - *Efficiency and Drag:* Aim to minimize both parasitic and lift-induced drag. Aspect ratio and airfoil selection are key. DarkAero 1 uses laminar flow airfoils and composite materials for smoothness. - *Why No Winglets:* Winglets would increase parasitic drag more than they would reduce lift-induced drag, making them inefficient for this design. - *Software Tools:* Modern software is used for analysis, not for initial design. The design is based on equations and iterative calculations. - *Conclusion:* The design involves many trade-offs, and everything is a balance between lift and drag. Future videos will discuss structural considerations.
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 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.
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!
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!
Most impressive part is free handing the perfect airfoils on the white board! Love seeing the progress and detailed explanations!
I am a mechanical engineer for farming equipment from Germany.
This content here is pure gold!
Thank you very much!
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!
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!
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.
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.
Best ‘Engineering Explained’ tribute I’ve seen so far :D
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.
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.
That's probably the best explanation of the Lift-Drag math in the whole Internet. Thank you, guys, very-very much.
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!!
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.
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!
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.
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.
This is the best concise and clearest video lesson on wing aerodynamics I've seen on UA-cam. Well done!
Phenomenal video, and a world class lesson from Ryley. 11/10. Keep up the amazing work 👍
Fantastic vid and a concise, cogent explanation of the concepts 👌🏽
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.
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.
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.
Excellent video man! Ive always wondered why ALL airplanes dont have winglets because Ive only seen aircrafts benefit from having them. Loved the explanation!
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.
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...
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
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 😎🎩♠️💙
After sitting in to a couple of lessons hearing about lift/drag etc. This is by far the best ever.
Thank!
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!
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.
Thank you for the clarity and logical progression in your explanation
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.
Keep coming, Dark Aero is not only designing a great aircraft, but inducing love for engineering
Super good explanation of the many criteria of wing design fundamentals. The take away…… compromise is inherent in any wing design.
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.
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!
Love how excited these guys are to geek out over specs.
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.
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!
Keep doing these educational videos ⚡🙏🏻
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.
a perfect lesson in compromise in design. Super interesting, your wing looks beautiful
Everything in one take. That’s amazing!
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!
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!
People of the sky are always pleasant to listen.
Best wishes!
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.
Thanks! Good review of the basics - but thin on the wingtip design choice factors. Yes, nice intro of induced and parasitic drag all to get to the 30 seconds of punch-line between 13:30 and 14:00. Glossed are factors that let winglets deliver 5-10% less cruise drag for airlines (also operating way out to the right on you drag chart). Additionally, common wingtip designs are not considered (ie hoerner, blended, canted etc). I guess the question the comes to mind is: why squared rather than any of the many tip designs will proven to reduce low angle of attack (cruise) drag?
13:45 with wingtips you reduce the induced drag that is true. But here is the magic part.
With wingtips you can "fill" your wing with higher lift coefficient. And you can build a smaller wing or a wing with less aspect ratio.
In the end a good airplane is a trade off design.
You have structural weight, wingtips add weight, but a smaller wing reduces it.
Find the best solution
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!
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 👍
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.
Awesome video. Takes me back to USN Aero Class from 38 years ago. Why split flaps? I did not hear that discussed.
Makes me more into aerospace engineering than i was before. Excellent video!
Superb !! Just amazing how rich the content is !
Nice explainer for summarizing the tradeoffs. Well done
Had to subscribe. Such brilliant videos with technical solutions clearly explained for all to understand. Beautiful aircraft
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!
This is great! I wish your video was around when I was graduating HS. It would have made a change in my career path.
Please keep doing videos like this. Love it! Thank you.
Been following the build from the beginning, you guys are putting out great content keep it up ! 🤘🏾
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!
That was good. I did not expect the reason for not having winglets to be quite so straightforward.
Fantastic video! Can’t wait for the test flights.
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!,
Amazing aero lesson wasn't expecting this from this video but it was a great explanation!
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.
Nicely explained. It shows that you understand what an aircraft design is all about.
Excellent explanation of a complex engineering topic. Well done!
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 UA-cam video. Your students are lucky to have you.
You're a great teacher and explainer... loved your presentation
As a non-pilot admirer of aircraft, this was a fantastic presentation that at no point did I feel underwater. Thank you!
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.
Just for understanding: Is the plane most efficient at cruise speed or at that lower minimum drag point?
I am assuming your engine is optimized for cruise speed. Would an electric one shift the efficiency point of distance per energy down towards that minimum drag point?
Absolutely lovely presentation - thanks!
Thanks for the great video. Have you considered tapering the tips (keeping the same wingspan)?
It should give you a somewhat better climb-rate, without any loss at the top end.
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.
This is really well done. I dont know much about aerodynamics, but I understood almost everything you said. Really great explanation!! Thanks so much!!
Fascinating, thank you. Appreciate the aeronautical engineering lecture. Looking forward to the next video.
Absolutely beautiful explanation! Keep up the great work!!
The next time your around a Cirrus take a really close look at that wing. They have a different chord/shape and twist. New designs also narrow the fuselage behind the wing, Diamond is a really good example of that. It improves airflow and reduces drag. And I think it's TBM/Mooney that has a twist wing to improve roll control. Just adding a "wiglet" is not always a good thing. Cessna Jet's is an example! JMHO's --gary
Your wing tips are blunt with just 1" radius transition from horizontal to vertical. Is this for ease of building or an aero design for max performance?
*Video Summary: Why we don't use winglets (DarkAero 1 Wing Design)*
*Key Points:*
- *Design Requirements:* DarkAero 1 aims for high-speed, long-range flight with a stall speed less than 60 knots. The wing should have a progressive stall from root to tip.
- *Lift and Drag:* Two fundamental aerodynamic forces. Lift is governed by air density, velocity, wing area, and lift coefficient. Drag is similar but focuses on drag coefficient.
- *Trade-offs:* High-speed cruise conflicts with low stall speed. The wing design is an iterative process to balance these conflicting requirements.
- *Stall Behavior:* A progressive stall is desired, starting at the root and moving towards the tip. Different airfoils are used at the root and tip to achieve this.
- *Efficiency and Drag:* Aim to minimize both parasitic and lift-induced drag. Aspect ratio and airfoil selection are key. DarkAero 1 uses laminar flow airfoils and composite materials for smoothness.
- *Why No Winglets:* Winglets would increase parasitic drag more than they would reduce lift-induced drag, making them inefficient for this design.
- *Software Tools:* Modern software is used for analysis, not for initial design. The design is based on equations and iterative calculations.
- *Conclusion:* The design involves many trade-offs, and everything is a balance between lift and drag. Future videos will discuss structural considerations.
Brilliant content! Can’t wait to get back for the second course on mold design sometime soon.
Amazing lesson. So much value in this short video.
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...
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.
Great explanation of wing design, in a nice short video, fantastic!
This is a great lesson about airfoil design, honestly might send this to some of my student pilots!
Loved every minute of this video. Thank you very much guys for shearing all this info!
Can you place electric motors, with propellers, on the end of the wings to counteract wing tip drag?
I’d love to see a video like this for the propeller design.
Excellent and clear tutorial. Thank you, I learned something!
Take a look at the scrappy bush plane. Can take off and land slowly on rough terrain. Much more versatile than a tarmac plane