Are Skinny Aircraft Wings Better?
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- เผยแพร่เมื่อ 23 ก.ย. 2024
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I once wrote an aspect ratio design analysis program for RC sailplanes The program was based on Martin Simmons book on model aircraft aerodynamics and ran in basic 7 on a commodore 128D, gives you an idea of the vintage. What I found was that for a 100 inch span and fairly light wing loadings achievable in a balsa & spruce construction, sink rate was generally minimised at an aspect ratio between 10 - 13.
Just prior to that, this had in practice work out pretty well for a slow high lift floater flying calm & relatively inactive conditions. The model was a stretched and tapered wing version of a Soar Birdy 86" span with which I got 2nd place in my LSF national soaring comp Jerilderie Australia with just such a model. However, higher aspect ratios resulted in increasingly higher wing loadings and air speeds on an increasingly flatter glide slope. The improved glide slope did not out weight the adverse effect on sink rate due to higher airspeed. However, it did improve the models range and therefore ability to search for lift over a larger area & especially it's ability to do so in stronger wind conditions. So basically, it became a gambling game. I have put quite a lot of effort into optimising height from a bungee launch. I could pretty much get more launch height than than anyone else Because of the high camber wing & more rearward tow hook position, I had to hold a little down trim at the start of the tow to prevent the model doing a premature auto release while climbing vertically. It was astounding how much more height I was getting & there was winging to the committee, but everything was comp compliant. The only difference was that I had put the time and effort into trimming & preparing the equipment to get then best performance out of it that I could.
Anyway, I had 2 models at the time. 100" span using a scaled down Bird Of Time wing section. This is a much less cambered and thinner higher aspect ratio wing than the other model. Bothe models had similar wing loadings but this higher aspect ratio model was notably much faster had had a much flatter glide. It could cover a lot more ground searching for lift. However, that particular competition had cool weather and calm conditions & the floated won out over it by quite a lot.
My opinion though remains that it would have gone the other way if conditions had been windier with more active lift.
For these 2 modes, it would normally be the case that the broader wing should have the less cambered section and the higher aspect wing should be the more cambered section, but this was early days for me, before I read Martins book. It's just that having studied the aerodynamics and then written the program removed the mystery & with it the interest, so I didn't continue to pursue sailplane design. I had also designed a few models with too short a moment arm which unfortunately led to overloaded (stalled) tailplane during F3B speed runs & diving into the deck. Normally the moment arm would be between AC wing and AC tailplane would be 4 times the mean wing chord for most model sail planes. In order to achieve balance with less nose weight, I went for 3 chords, which was fine for normal soaring flight, not fine at speed though. I think the 3.5 chords might have been adequate though. As it was, I would start a ballast loaded speed run and at some point the nose would continue to drop despite up elevator control.
After that I bought a Sirus (2Ch) that someone else built, it clapped it's wings slope soaring over sand dunes. Repaired it, strengthened the wings with a new I beam main spar, redesigned the tips & rebuilt the rudder & tailplane with a geodetic structure. Installed a completely hidden in a closed loop rudder hidden cable system as the fin is suitable thick.
The model died one day when another pilot switched on their TX on an adjacent channel.
I had had many thermal flights well over an hour with that model, only landing to rest my neck.
That model had a fairly high aspect ratio high camber wing. It could cover a lot of ground sniffing out lift, reasonably good upwind speed, not exceptional. It could would loose out against a floater if no lift was found, but most time I'd find lift. It had no provision for ballast though. I had it disappearing into clout a few times. The fully flying tailplane had differential control throw. I could half loop over to inverted to drop out of the cloud base lift & bring it back home. Rudder roll it to upright flight again for landing. All in all it was a rather nice model to fly. see below.
Soar Birdy Var 86 inch Span about 78
drive.google.com/file/d/1UM-ZV-CWWSXPEDwUoD5rfBmplhYUEEB8/view?usp=share_link
Bird Of Time Section 100 in Span about 79
drive.google.com/file/d/1iqbyN6a5l76PElb6qGHS8oobFz6cb9hM/view?usp=share_link
An RC flying wing glider I designed about 77:
drive.google.com/file/d/1s-Z7ob6zHEiKgaB_0w8HHgwYFyc8hrrZ/view?usp=share_link
A Sirus I had in the 80s Many thermal flights well over an hour.
drive.google.com/file/d/1cDgETfMoPqNyu_TfJcuCd4v6dA-A6w60/view?usp=share_link
This post is a goldmine, thank you!!!
@@thinkflight Ta,
Then you may also be interested: I did a statistical analyse aimed to best approximate the "ideal" elliptical span loading with a simple double taper wing. It turns out that the standard deviation on the span loading's departure from elliptical is minimised when the inner panel is a constant chord for 40% of the semi span & the outer panel tapers to 60% of the root chord at the tip. I never built it though. It would be slightly unusual in that the centre panel is shorter than that of most double taper wings & the tip chord somewhat less as well. Most tip chords go to about 70%, maybe even 66,6% (2/3) of the root. Many are scared of tip stall & cautious of making the tip chord too short for that reason, but combining a small increase in camber with a little washout, gives the tip the same AOA and higher Cl max before stall (safe from tip stall), without changing its zero lift reference relative to the rest of the wing. Anyway, it "should" make for a slightly more efficient wing, not that you'd notice really, maybe a few seconds extra duration in dead air.
On the other hand, you'd get a lot more benefit from adopting Prandtl's bell shaped lift distribution at the same root bending moment as that extends the span very significantly reducing induced drag. The maths looks a bit tricky to me though. There is a fair bit on the net about this these days and in English translation no less!
Great breakdown, I think its worth mentioning that swept wings, and the delta wing of your foam model, are generally designed with trans and super sonic effects in mind. Swept wings can lower the effective mach number and delay the formation of transsonic effects. Delta wings keep the wings out of the shock formed by the nose at supersonic speeds and generate lift differently at lower speeds, hence the larger angle of attack
I would like to kwow how a flat wing can acually give any sustentation, 1 of aeronautics and I'm not understanding taht.
Love these technical shorts. I'd love to see some content on how to pick an aerofoil based on the type of model you're building.
Probably a little too niche to put food on the table. Now that I think about it, pretty sure this one was too haha.
@@thinkflight I'll watch it a few thousand times while building my goblin 😅
@@WipeoutFPV I appreciate that!😂
@@thinkflight i was under the impression you're doing all this just for fun. if a little bit of video like this puts food on the table in CA then i wonder what it could do for me living in some cheap place.
Great edit! Good times!
Yes it was!
I just finished my Aerodynamics class. It seems like at low speeds M
The crazy thin wings on the F-104 are a great example of that. Only downside is that they do NOT handle stalls well.
Almost seamless these adlibs (focus on almost) brilliant chaps I am always in awe of your work.
Long skinny wings (high aspect ratio) have lower drag than fat wings (low aspect ratio) also at low aspect wings have greater resistance to stalling, the high aspect can stall unexpectedly. See gliders and jet fighters.
Its interesting how this can change based on scale...from my understanding, once you start getting small enough, leading edge drag starts to become higher than skin drag, so shorter wings start to become more efficient again. ...at least, thats what I remember...yeah dont quote me on that lol
Its more of a reynolds number thing, when the reynolds numbers get really low things become inefficient again so at really small scales, keeping the chord as big as possible becomes your best bet to keep the reynolds numbers as high as possible rather than going for aspect ratio.
At the speeds reachable by our RC airplanes where compressability effects are not a concern a high aspect ratio wing of the same wing area will consistently outperform a low aspect ratio wing even at high speed. The low aspect ratio wing will not have a smaller forward profile area because the thickness of the wing is proportional to the chord length. There's a reason the speed records for RC planes are held by high aspect ratio sailplanes dynamic soaring.
When a lower aspect ratio wing makes sense it's because of structural limits, span limits, stall characteristics, and manufacturability, not because you want to fly faster.
if the wing area is kept contant, there is a point after which an even higher ar will decrease performance due to the decrease in re number, meaning the airfoils stop working properly
so the saying "higher ar is always better" is technically not correct
i once did a number of simulations testing this, on a rectangular planform wing with a wing area of 0.1m² (10cm chord at 1m span)
i varied the ar and aoa and compared performance with L/D
can't remember the airfoil rn
up until an Ar of 25.6 (span 1.6m, chord 6.25cm) L/D kept increasing to a maximum value of 18.5
at higher Ar's L/D dropped again
@@marc_frank If your narrow wing chord is giving you Reynolds number problems just fly faster on cold days to get the Re back up and you're golden! But yes funky stuff starts to happen at low Reynolds numbers and it can make sense to go with a lower aspect ratio wing to avoid that.
@@Dovorans the program i used to simulate these values calulactes performance in stationary flight
meaning it already increased speed for the lower chord wings
the wings above that Ar of 25.6 still performed worse
sorry, your comment is flawed. for one thing, it is not correct to say '...the thickness of the wing is proportional to' wing thickness is a design parameter; it is Expressed as a 'percentage of chord length' !!! this is not the same as saying that there is a proportional relationship between profile thickness and chord length.
@@daviddavids2884 while you are correct, that airfoil thickness is a design parameter, if the chord length is varied without changing the airfoil thickness, chamber, ... (scaling instead of stretching), then airfoil thickness is in direct linear proportional relationship to chord lenght. the scaling factor "airfoil thickness in %" stays the same
this also means, that if the aspect ratio of a wing is changed while keeping wing area and airfoil % thickness constant, the frontal area also stays constant
For your cool flying wing:
How much maH does the 2s lipo you are using have? Also what motor are you using?
You can see the same effect in birds: the long slender wings of an albatross, vs the wings of a peregrine falcon. Another important part of the equation is maneuverability. Multiple factors are at play, but one important aspect is the spatial relation between the center of mass and the center of the lift.
Long thin wings produce less drag, but are much more unforgivable in terms of actually flying them, prone to ip stalls, prone to sudden loss of lift due to the narrow chord, harder to build... There is a lot of pros and cons to a high aspect ratio wing..
Amazing video as always, also loved the YF-23 at the beginning. Just a correction on a tecnical note: multiple time you said that high AR (aspect ratio) is for grater efficiency at lower speed. This is not entirely correct, in fact the AR determines mainly the max aerodynamic efficiency (lift to drag ratio), while the speed where the peak efficiency is achieved is determined by the wing loading (aircraft weight over wing aera). Also sometimes is better to think about not the speed of max efficiency, but rather the dynamic pressure of max efficiency (q = 1/2* TAS^2 *rho); in this way you take out of the equation flight altitude (the higher you fly the lower the air density so the speed of max eff. increases). In my opinion the best way to undesteand intuitively those concept is by "playing" with the equation; I use Desmos for plotting the graps (you can set up sliders to visualize what happens when you change various parameter); than Matlab for more complex optimization.
It would be cool if you could design retractable wings that change the frontal area and aspect ratio of your plane as you change speed
Please share the design for 3d printing or make a build video. Does it really fly for 3 hours with 2s battery? please elaborate it
if the wing area is kept contant, there is a point after which an even higher ar will decrease performance due to the decrease in re number, meaning the airfoils stop working properly
so the saying "higher ar is always better" is technically not correct
i once did a number of simulations testing this, on a rectangular planform wing with a wing area of 0.1m² (10cm chord at 1m span)
i varied the ar and aoa and compared performance with L/D
can't remember the airfoil rn
up until an Ar of 25.6 (span 1.6m, chord 6.25cm) L/D kept increasing to a maximum value of 18.5
at higher Ar's L/D dropped again
Oh, I was about to ask if an infinite wing has zero induced drag, but this answers my question in a way.
That's cool! But for any somewhat normal (or even manufacturable) plane you wouldn't get an aspect ratio of 25, so it's fine to say it, since he said he didn't want to overcomplicate things
@Captive Nut Theoretically the induced drag would be zero yes, but other problems start to emerge (the lower Re number, but mainly structural)
You are also tend towards increasing frontal area with higher Ar. The particular amount depends on thickness and how it varies across the wing for each Ar.
Another issue with the statement is that structurally high AR is not always better. It requires more weight and structure to continually increase AR, but for RC purposes it doesn’t matter much
I smiled through the whole episode all while learning more about aerodynamics! And I did enjoy the montage, keep it coming Think Flight!
Now I wanna make the ~lowest~ aspect ratio wing
I don't know the full extent of what you mean, but with you saying it I want to see it.
Flying broom for next years halloween
The flying wing looks truly awesome.
Very interesting and fun show!!! Your shop is the cat’s meow! I appreciate you explanation of wing design and will implement it on our next balsa glider build!
We are having mathematics, art/ design, fabricate school over the summer. Thanks a ton!!!
That plane with the skinny wing would make a good FPV cruiser glider if fitted with a bigger battery and long range antennas, also if fitting with a 360 degree gimbal for FPV camera with head track on the nose would basically give you the best flight experience but due to FAA regulation would make such flight impossible without the flight clearance waiver. Still would make a good slope or flat land e-glider, now would be nice if plans are available to build one.
guys, nice video, but maybe keep the very obviously fake acting down. we like you guys as you are, technical, nerdy, and detailed. not like a reality show. My two cents anyways
Agreed, it's a bit cringe without the goofyness that some other TH-camrs have that make the cringe palatable. You guys are just too intelligent and methodical and goal oriented for that. Which is completely fine!
God yes. Just good information without wasting our time and brain cells.
I for one love the acting
The acting is terrible, but that’s part of the charm….
Won't stop can't stop :)
You two guys are the coolest bros out there in this aeronerdy youtube world. I wish Samm was still around and that Peter Sripol lived closer to the West Coast.
Did you catch any ridge lift off of that bluff my dude? the efficiency was probably most epic if you did!
It was ALMOST enough lift to go without the motor.
@0:44 y'all protest to fiercely I think. Confident people don't need to spend any amount of time diminishing others and virtue signalling about their manly diet.
the wing is beautiful , so elegant !
You sir have a amazing skill set. I really enjoy your content. Thanks...
its amazing to see ppl creating such creative designs...
You knwo something about to teach you more than primary school when it start with "This video is brought to you by Squarspace"
The mountain in the beginning is in my back yard...too bad I missed seeing the SR cleaning up all that litter!
Surprised you didn't hear it, that thing is LOUD
Great video, footage and explanation
Building skills 100 👍
Acting skills 0 🤣
Come on, maybe 20 of 100? They managed to say the lines and probably even came up with themthemselves. That's more than some would've done
I keep coming back to this video because of the cool music when you are flying at the beach.
I'd love to see a build video on the skinny wing! Particulary on the profile(s) used.
At the speeds these things fly, it really doesn’t matter much.
@@brucebaxter6923 Please elaborate. Having watched the last part of the video several times, it looks like a Clarke-Y, or something similar flat bottom profile.
@@janspoelstra8309
How much detail do you want?
Start with temperature being the speed that molecules move at.
Then brownIan motion being the movement of those molecules.
Then the noise in water pipes when the pipe is small enough or the flow high enough caused by the turbulence as flow changes direction.
Then Reynolds number being the point where a wing moves through air faster than brownIan motion can naturally flow the air around it without becoming turbulent.
Short version, toy planes fly so slow a flat sheet of foam will fly.
Ok, after that the charts are online to determine wing loading by speed and mass and then aspect ratio by speed.
@@brucebaxter6923 You might want to do some research on flying wings before you go making simplistic claims.
@@admacdo
I have.
And for that size and shape a flat plate is good enough.
Larger sizes you need to blend in reflex towards the wing tips, but none of us are building them.
Long skinny wings are definitely good for efficiency, but I've noticed issues with very light planes. When the wing span is large in relation to the airplane weight, the reynolds number is fairly low. Below about 50,000 most airfoil designs have lots of issues, so the L/D is very low. In this case having the airplane fly faster at a lower AoA is better due to the increased reynolds number and therefore increased L/D.
I'd love to see your process for designing when using a computer
Great Collab video, well done fellas!
Low and slow. Beautiful 😊
Nice seeing the Queen Mary some 15 miles to the north, in Log Beach!
I like this partnership
Here's a question: At what *actual* velocities does the crossover happen between induced and parasitic drag? Is this different for our small RC aircraft? How does airfoil shape (or other important factors) effect this? What other important factors contribute?
Obviously, there are (I'm sure) decades of math to figure this out based on as many variables as there are stars in the milky way galaxy.
I would *LOVE* if you could do an in-depth analysis of choosing a specific aspect ratio and/or airfoil shape.
How did you choose the specific wing profile for your high efficiency wing in this video?
@thinkflight What is the music artist & title at the end of the video?
Also, I do really like the color scheme on the slender flying wing.
I love that wing. Efficiency is beautiful
You just described the most commonly described differences between low and high aspect ratio wings.
But, you should also note the reasons why some people have suggested replacing the stubby wings of the F-16 with a delta wing, and why relatively high aspect swept wings might be preferred in some cases vs a delta wing that "fills in" all that space behind the leading edge of the narrow wing.
In other words, there's a lot more to the wing form than just whether the wing is high or low aspect ratio.
Does anyone have the plans for the flying wing or another similar wing please?
I know skinny wings are more efficient, but what about solar powered aircraft? The problem is I'm not a mathematician or an airplane designer so I don't know how to figure this out. I have identified a few issues.
1.Skinny wings are more efficient, but broader wings, for the same length, are stronger and larger so can attach more solar panels but are heavier... I'm getting rocket equation vibes.
2. Do we even want to put solar panels across the entire exposed surface of the wing?
3. Solar panels have essentially fixed weight per unit area, wings do not, or don't have too.
4. Solar panels are also really heavy compared to normal wing structure materials.
I think the takeaway is that solar aircraft have very different design requirements and shouldn't be just 'regular' wings modified for having solar panels.
It depends on how much flying you want to do away from max solar efficiency. If you are flying mid day then yes, maximize area and go with whatever gives you the lightest airframe weight. If you have to fly through the night, you need very long, very skinny, marginal strength wings to minimize sink rate.
Anybody else jealous of what looks like an amazing dynamic soaring spot?
If you have not DSd up there yet I will be very Angry! 😁
Believe that's Chino Hills State Park and yes it's amazing. Every day there was incredibly special. It's a long drive so you'd fly the whole day or until your planes couldn't anymore. The other spot is Huntington Beach across from the power plant. Don't live in CA anymore and mostly fly drones now but fondly remember the incredible slope soaring. Also look up Point Fermin slope soaring.
@@davidbrady5618 the south of the UK doesn't have much in the way of dynamic soaring spots, we have some nice slopes tho. very rare to get a nice sharp ridge in the UK. Unfortunately:(
Could be wrong but the front side is pretty chaotic topographically, don't think there will be much DSing happening there.
The proper term from "skinny" wings is "high aspect ratio" which is the span squared divided by the wing area
I'm loving the content man!
Neat to have the performance of both type of wings demonstrated. Can't wait to see more. Keep the great videos coming!
Doubt you will see this but I was wondering why you designed the low speed aircraft with swept wings. I did an extremely minimal amount of research and found that swept wing designs specifically deal with wave drag from transonic and supersonic flight. In the case of an electric drone, those speeds are not possible.
All I can think about in this video is getting a few more nano goblins and taping them together.
02:21 ...and the Piaggio avanti is loud a fudge
Hello I love that skinny flying wings and I built same type today please I will want to know more and how you found the CG . Am you biggest fan
Wing shape and size comes down to what kind of performance the plane is being designed for, a lot of factors are considered when designing a wing
Awesome video man
An old question: does sweeping back (keeping its transectional profile) increase the wing area without changing its aspect ratio?
no
sweep back make sense only fro flying wing (for stability) and compressible aerodynamics, apart from this only drawbacks
@@antonioesposito8071 also stabilises the yaw axis and improves drag....
@@helicopter234 yeah forgot about the yaw stabilization, but i doubt there is any drag improvement in subsonic scenario
You guys make a great team. Coupla dorks partying with planes. Entertaining.
Man i wanna make that wing so bad
How much does the ballast cost?
''EXACTLY 25 cents''
omg yes. ever since this was shown in the shop tour I've wanted to hear more
Generally, a high-aspect wing-one that has a thinner foil-is more aerodynamically efficient.
High aspect ratio more efficient. Minimum of 4” chord.
I really hope a Strix version of this airplane lands in store soon
I'm a low aspect ratio kind of person lol
It's all about flight envelope. Skinny wings have no air brakes, so they go fast on little power but fall out of the sky at low speed. Wider, thicker airfoils have a wider flight envelope, sacrificing a little top speed but needing more power. Thick and wide airfoils are much more fun to fly.
I’m loving this wing … what … where can I get one it would be perfect for my area SilverWood Lake
Insults vegans in the first minuet. Subscribed
High Aspect Ratio = skinny
I love reading all the comments , seeing everyone accomplishments. lol
i much prefer the thin airfoils, this looks much more elegant in flight
have published the flying wing plans?
You live in Moreno Valley or elsewhere in socal?
Would love a video on pusher vs tractor configuration.
bell shaped or elipse shaped lift distribution?
Soaring Birds use bell shaped of course. - Al Bowers
Would you consider using this platform to test using mid wing mounted motors to counter act the mid wing vortex you noticed in your wing tip mounted motor? I've always wondered if that's the key to efficiency in flying wings. It looks like you either had the same or a similar idea with the vertical stabilizer placement. Just a thought, I'd be very interested in the result. Love your videos! Keep it up!!
Great in-flight footage!
Was that SLO?
Great Video. Need a build video on that one! Wouldn't extending the front end out another inch moving everything slightly more forward create a more balanced load so you don't have to add quarters or will that create more drag causing making it less efficient ???
Yes, if he was trying to perfect the most efficient one yet but remember it's just a one off test vehicle, not the start of a production line.
Remember, "Perfect is the enemy of good" (look quote up)
Balance on an airplane is almost impossible to get right every time. When you change the position of the battery etc. It can be done but it is a test vehicle where the good part is that you can test different batteries and so on
Proper shoes for the terrain. Haha
Looks like you had fun!
is that grey skinny plane 3d printed? if yes how can we gey the stl files
So.. this couldnt be done in Canada legally, as in flying on a beach I think. Is this allowed in US?
I would immediately say yes without seeing the video yet and just pointing to world record in paper planes.
That was my 1st thought as well 'how are you going to land that thing', I mean, those rocks are rather unforgiving.
Is this the Sander of ImmersionRC?
@@thinkflight yessir, guilty as charged!
@@sandersassen I remember you from FPVLab way back. Honestly don't even remember what my screen name was back then....
1:29 i thought my headphones were giving up here
Thats beautiful
I am loving this series
Box Springs Mountain in Moreno Valley/Riverside?
Slope soaring is just the best of flying. Seeking air flows surfing with them I cannot stop doing it (well until my eyes tell me stop with tears)
"Just catch it" he's sokka
Hello, please one question.. How many degrees have the swept wing? And what wingspan have the wing?thanks
You forgot your surfboards...
How about endurance of this long thin wing RC ?
Love comparison videos while teaching aero concept; more please. Also great aerial chase video on the montage. Was that from a quad?
The downside of long skinny wings is that they stall easier.
Hey guys, I am building an RC with Canard and both wing and canard the same size but my question what’s the thrust to weight ration should be to ge a fast small RC? Is it 0.8 of the total weight of the plane? Or less or more ! What’s the rule of thumb plz
Is that one of the hills dynamic soaring gliders use? Looks familiar from videos. Have you ever done dsing?
It is not afaik, and I have never done dsing myself.
Slower flight intrigues me.
Could you make that last airplane at the end fpv? Cause that would be a awesome fpv wing, it's flight characteristics are amazing!!
Sure! I doubt I would enjoy such an aspect ratio for FPV as its a little docile but others may prefer that!
Seems like something that could be good maybe scaled down and like a chill park cruiser? Idk, how small can winged rc aircraft get?
At what velocity does low aspect ratio start to perform poorly
Dare we ask for plans?
Dude you are funny as shit. Lean into that. Love it.
Nah man I'm here for neat projects not bland open mic night
@@nekkowe just trying to give him some confidence to be funny when he wants. But ya it’s the projects and intense attention to detail that make his videos great.
I would love to se a building video of such an aircraft. I men an airplane withe a height expect ratio. Because I am considering to build such an flying wing out of my broken rc plane. Very nice video keep it up 🙂
Summary: at higher speeds, you don't need a lot of wing to produce lift. It creates unnecessary drag.
But honestly, i expected you to talk about skinny wings vs wide wings, while the length is the same.
Can you share the flying wing design directions I want to make one🙂