/sci/ - Science & Math

[Anonymous No.10131872]

Redpill me on winglets. Is there any formal theory of how to design these things, or is it all trial and error of getting them to cancel wingtip vortices? Trying to make my RC model more efficient.

[Anonymous No.10131889]

>>10131872
>implying aeronautical engineering has ever had a rigorous theory
it's trial and error bro. aeronautical engineering has always been a theoretical clusterfuck to the high heavens. the legend is that to this day, airplane engineers argue about why aerofoils work

[Anonymous No.10131903]

>>10131889
Well all the papers I've read so far seem to indicate that when it comes to designing winglets for a specific wing, it's trial and error. Could you point me to any resources?

[Anonymous No.10131932]

>>10131889
Aerofoils are like an inverted wing and push things down

>>10131872
When a plane flies, the pression below the wing is stronger, that creates the vortex things. You could make a longer wing to reduce the vortex but winglets do the same thing in less space and look cool.

[Anonymous No.10131943]

>>10131932
Wings are aerofoils. How do wings work? Don't tell me to goggle it. I have heard way too many contradictory explanations.

[Anonymous No.10131945]

>>10131932
But how do I design them in an optimal way? When I try making them in XFLR5 they usually just end up adding to the induced drag unless I get lucky.

[Anonymous No.10131949]

>>10131932
>and look cool.
No they don't. They're the plane equivalent of naruto running.

[Anonymous No.10131953]

>>10131949
>They're the plane equivalent of naruto running.
Fucking dead.

[Anonymous No.10131961]

>>10131943
The planes get fast and they move their tip a bit up. The air touches under the wing and holds the plane in the air. Try putting your hand out of a car when it's fast to see it better.
>>10131945
Bend the wing and make the winglet be close to 5° We don't have any equations yet
>>10131949
B-but Naruto running is cool!

[Anonymous No.10131975]

>everybody in this thread right now

[Anonymous No.10131980]

>>10131975
You are in this thread too

[Anonymous No.10131981]

>>10131980
Me on the left

[Anonymous No.10131983]

>>10131961
>make the winglet be close to 5°
Do you mean 5 degrees twist, or 85 degrees dihedral?

>>10131975
Care to contribute?

[Anonymous No.10131991]

>>10131983
Dihedral, you don't need the twist
>>10131981
Me on the right

[Anonymous No.10132010]

>>10131991
Should I use a symmetric foil?

[Anonymous No.10132023]

From a mathematical point of view it's just finding the solution of a differential equation.
But the equation is too complicated for a purely theoretical solution, so we use approximations and simulation. Another problem by doing that is that even if we can run our simulation and find a solution, there might be other solutions.

[Anonymous No.10132029]

>>10132010
I think a semi-symmetrical one that is a little thinner on the bottom would be better but a symmetrical one is good too

[Anonymous No.10132033]

>>10132023
>math
>math
>math
>math
>fuck
>derivative was done wrong

[Anonymous No.10132042]

>>10131991
Me in the middle.

[Anonymous No.10132046]

>>10131872
I'm in an aircraft design course and have no fucking idea.

[Anonymous No.10132057]

>>10132042
Closest left to middle

[Anonymous No.10132077]

>>10132057
fuck, you took grug? bastard....

[Anonymous No.10132086]

>>10132046
well shit

[Anonymous No.10132093]

>>10132086
I can check my textbook for you.

[Anonymous No.10132099]

>>10131872
>is there any formal theory of how to design these things

Copy nature

[Anonymous No.10132102]

>>10132093
My textbook is not helpful, sorry.

[Anonymous No.10132111]

I thought a wing was half a Venturi the air on the top has to go as fast as the air on the bottom and therefore, must speed up and this create a low pressure on the top of the wing. There is probably some dumb math with using surface areas. But winglets are pretty much just flat vertical shit to keep the air from slipping off the wing and reduce inconsistencies in pressure differential.

[El Arcón No.10132217]

>>10131872
>any formal theory of how to design these things
Navier-Stokes

[Anonymous No.10132232]

>>10132217
Unironically kill yourself schizo.

[Anonymous No.10132236]

>>10131949
Those are swept wings you big dumbo, doubly so for ones where the root is thinner than the tip.

[Anonymous No.10132275]

>>10132236
>the root is thinner than the tip

[Anonymous No.10132323]

>>10131872
It depends on the aircraft. The wings mediate air pressure, not all are the same because the payload they're carrying isn't the same. Some airplanes need to good fast so they have shorter wings and a thin fuselage. Large slow planes have larger wings that capture more area of air pressure which causes more lift. It is trial and error because there is no "one size fits all" when if comes to aircraft. The USA tried to create a "one size fits all" plane and it was an engineering nightmare that never ended up doing any of things it was supposed to do efficiently and more effectively than already existing aircraft. A "jack of all master of none" type.

[Anonymous No.10132559]

>>10131872
>Redpill me
GTFO pill-popping /pol/esmoker

[Anonymous No.10132588]

>>10132111
>low pressure meme
its just a tilted plate that accelerates air down making a reaction force. the airfoil shape stops separation on the back of the plate

[Anonymous No.10132607]

>>10132588
Wrong

[Anonymous No.10132628]

>>10132607
elaborate (faggot)

[Anonymous No.10132849]

>>10131949
>They're the plane equivalent of naruto running

[Anonymous No.10133127]

>>10132588
Yeah that's what he said, low pressure area
Those are the same fucking thing

[Anonymous No.10133254]

>>10131949
Best post in weeks

[Anonymous No.10133565]

TLDR: Don't bother, doesn't make sense for RC.

Aerospace Engineer here. While I mostly design satellites, I know a bit about aerodynamics. Here is the first paper I found on winglet design. http://www.diva-portal.org/smash/get/diva2:547954/FULLTEXT01


In general, we first start with ideas about vortex mitigation with minimal additional parametric drag and then try several different approaches using computer simulations. While there is trial and error, it certainly isn't guess and check. Also, I really wouldn't recommend putting winglets on an RC model, unless you just like the look.

This guy even flew a model aircraft across the ocean without winglets. https://en.wikipedia.org/wiki/The_Spirit_of_Butts%27_Farm

Also, on a higher level we all agree on how aerodynamics work. We just disagree on the easiest way to fake an accurate simulation on a computer and the easiest way to explain aerodynamics to laypeople. If you really want, I could try to explain, without the simplifications that leads the general public to expect that we have no consensus about what is happening, but it is a long and rather tricky explanation that took me a whole class to learn in college.

[Anonymous No.10133571]

>>10131872
it's something about vortex created under a wing that goes in the opposite sides

[Anonymous No.10133592]

>>10131872
It's easier to design than you'd think. As you know, every wing has a dihedral, sweep, taper and twist. For winglets, twist will be always 0, and as a first approximation you can assume the sweep will be same as the original wing. You can design thus try different dihedrals and taper ratios to try to get higher L/D using a simple panel code.

[Anonymous No.10133734]

>>10133565
>TLDR: Don't bother, doesn't make sense for RC.
But induced drag is highest at low airspeeds. If anything, wouldn't it make more sense to use them on RC than on full scale aircraft? XFLR5 is showing that up to 75-80% of my drag is coming from induced drag.

[Anonymous No.10134275]

Why not put angled blades on the wingtip so that the vortex swirls around them and it acts like a turbine, regenerating thrust from the energy lost due to induced drag?

[Anonymous No.10134467]

>>10133127
low pressure area is the same as accelerating air downward? no it's not. that goober doesn't even know the air has to move down for the wing to have an upward force

[Anonymous No.10134619]

>>10131872
>winglets
When will they learn?

[Anonymous No.10135133]

>>10134275
W-would this actually work?

[Anonymous No.10135301]

>>10131872
>Trying to make my RC model more efficient.
Just make them detachable. That way you can try testing without them, and with them in various sizes.
Also, it works for paper planes.

[Anonymous No.10135310]

>>10134275

kek

10/10 would fail you again on the midterm exam

[Anonymous No.10135898]

>>10135310
Why? Winglets designed with a toe angle regenerate thrust (AKA most winglets).

[Anonymous No.10135926]

>>10133565
Ye go ahead i wanna hear it

[Anonymous No.10135929]

>>10134275
pls stop

[Anonymous No.10135954]

>>10135310
>>10135929
Then explain how this works you illiterate fags
>https:// ntrs.nasa.gov/ search.jsp ? R = 1 9 9 1 0 0 6 3 9 9 1
>Wingtip vortex turbine investigation for vortex energy recovery

[Anonymous No.10135978]

>>10134275
Why not just circumvent the whole problem by cutting the tip off the wing?

[Anonymous No.10135980]

Winglets. When will they learn?

[Anonymous No.10136248]

>>10135310
>>10135929
>>10135954
BTFO
T
F
O

[Anonymous No.10136494]

>>10133734
XFLR5 is garbage

[Anonymous No.10136579]

>>10131943
Wings work by pushing air downwards

[Anonymous No.10137065]

>>10136494
Why?

[Anonymous No.10137073]

>>10131949
>They're the plane equivalent of naruto running
Jesus Christ how will the aviation industry ever recover from this crippling blow? Might as well pack it in and go back to trains and boats folks.

[Anonymous No.10137083]

>>10131872
is this rc model for a personal hobby or is it for a class

just wondering

Typically the idea is extending the wing the most reduces the turbulence and area effected
But you have to consider not unbalancing the plane in the process
I've had the idea of a circular wing for a while and working on a model but I have no idea of the mechanical implementation. The idea is the right geometry wouldn't have an edge to shed vortices but the challenge is distributing the airfoil around the circle to best spread the lift

[Anonymous No.10137379]

>>10131872
In most cases you'd get better results it you just make your wings longer with none of this winglets bullshit. They put them on airliners because of wing span constraints imposed by existing airports and relevant facilities. Also the picture is highly exagerrated, while the winglets do reduce wingtip vortices and related induced drag, it's in the order of like 5%, which might be interesting for a commercial airliner, but a complete waste of time and effort for a diy rc aircraft, given you're lucky if you don't actually make things worse instead since you have to ask about it on 4chan.

[Anonymous No.10137479]

>>10132628
>faggot
Why the homophobia?

[Anonymous No.10138393]

>>10137083
>is this rc model for a personal hobby or is it for a class
A bit of both.

[Anonymous No.10139080]

>>10137065
Vortex panel methods are for niggers and faggots too dumb or lazy to use real CFD software.
Ansys Fluent student's version is free by the way so it's not like cost is an excuse.

[Anonymous No.10139703]

>>10139080
What if I don't have the computer for that?

[Anonymous No.10139731]

you fags still use winglets? LOL join the wave of future

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160003578.pdf

[Anonymous No.10139739]

>>10137083
>wouldn't have an edge to shed vortices
no

[Anonymous No.10140131]

>>10139703
500k cells usually take less than half an hour to compute on a single core. Unless you're optimising a design/transient problem that's sufficient.
2D problems aren't an issue at all.

[Anonymous No.10140424]

>>10131949
kek, winglets eternally btfo

[Anonymous No.10140558]

>>10131889
>airplane engineers argue about why aerofoils work
It's mostly because they are brainlets who cannot figure out that pressure differential and conservation of momentum are just two different mathematical approaches to modelling the same system with different degrees of granularity

[Anonymous No.10140564]

>>10131872
Just like anything in engineering, it's a mix of science and voodoo. Science helps you establish ground rules and test designs, the voodoo appears in exploring the infinite solution space for local minima that suit your cost-time-quality criteria.

[Anonymous No.10140726]

>>10131872
Someone pls gib analytical solution to navier stokes

[Anonymous No.10140748]

>>10135978
Or, in all seriousness, make the wing loop-shaped so that there are no wingtips at all?

[Anonymous No.10140762]

>>10140748

[Anonymous No.10141053]

>>10139731

[Anonymous No.10142410]

No wingtips
https://en.wikipedia.org/wiki/Closed_wing

[Anonymous No.10142768]

>>10133565
>Also, on a higher level we all agree on how aerodynamics work.
in the red corner: extremists who claim that everything from airfoils to sails works because muh Bernoulli. in the black corner: an airfoil cut from a circular cylinder, parallel with the axis of the cilinder, which flies like a brick.

[Anonymous No.10142770]

>>10131872
when will winglets recover?

[Anonymous No.10142795]

Anyone who says Bernoullli, how can planes fly upside down?

[Anonymous No.10142815]

>>10131943
They work by magic.

[Anonymous No.10142878]

>>10140748
That's not practical because then much of the lift generated by your wing is wasted sideways. You could just use a way smaller wing.

[Anonymous No.10142892]

>>10131943
The airfoil pushes air particles down to accelerate the wing up. It's just that with fluid dynamics being as complicated as they are there are all sorts of secondary interactions between air particles themselves that mean just using an angled flat plate to generate lift is really inefficient compared to using an airfoil specifically designed to keep the flow hugging the surfaces. It's generally more practical to think of the air flow redirection in terms of the pressure differential generated - which is a mathematical abstraction

The reason there is disagreement about this shit is that engineers are brainlets who do not understand that mathematical models are just that - purely semantic constructs that exist in people's heads to approximate some observed phenomenon to a desired degree of accuracy.

[Anonymous No.10142910]

>>10131949
There goes the thread. Pack it up.
We've just been meme'd on

[Anonymous No.10142935]

>>10131943
Wings make air fall down instead of the plane, that's all there's to it. Bernoulli, airfoils, and all the other complicated stuff are just different ways to have a more detailed look into certain aspects of the whole thing. The only ones who argue about those are brainlets who can't see the forest for the trees.

[Anonymous No.10142936]

>>10142795
The same way they usually do. Tilt it downwards enough and the air will start to move faster on the pressure side generating negative lift.

[Anonymous No.10142949]

>>10142936
The air moving faster on the upper side and the pressure differential is just a consequence of the fact that you're redirecting it downwards.

[Anonymous No.10142954]

>>10142949
The downwards redirection is just a consequence of the fact that you're creating a pressure differential.

[Anonymous No.10142965]

>>10131991
>Dihedral, you don't need the twist

Kite designer here, I have nothing really to add to the thread at this point but just enjoy seeing the word "dihedral."

Carry on...

[Anonymous No.10142997]

>>10131889
>the legend is that to this day, airplane engineers argue about why aerofoils work
No qualified aerospace engineer argues about this. Hell, no one that has taken Fluids I & II should be confused as to why airfoils work.

[Anonymous No.10143011]

>>10131872
There are FAA advisory circulars available as on line PDFs. (AC 43 13 1B) for example. Used for the training of aircraft mechanics. It may be a better place to look. There have been several good answers here that are always met with another skillfully calling them a retard.

[Anonymous No.10143017]

>>10131949
hey mom, I'm in the screencap.