For those of us who didn't know what these were, you can specify a 4 digit code that corrrelates with an airfoil shape, and here's how it works.
Show HN: Olelo Foil - NACA Airfoil Sim
11–20 of 21 posts
Re: Show HN: Olelo Foil - NACA Airfoil Sim
#12Earlier quoted context omitted.
Also, it looks like you might have a bug in generating the airfoil shape. An airfoil like the 8412, while extreme, is well-defined and constructible from NACA-style combination of thickness and camber forms; but you show it as having a "kink" on the bottom surface, which is definitely not correct.
841220 is interesting, if you want to see what a borg cube aerodynamics might look like.
LOL and it's also completely vertical
Re: Show HN: Olelo Foil - NACA Airfoil Sim
#13Unless you're planning to resolve the boundary layer and model separation (good luck...), you'd probably be better off using panel methods than NS. Look at XFoil or JavaFoil for available implementations.
I just pushed an update using spalart-allmaras turbulence model (somewhere in between NS and panel methods). Also updated the controls to use arrow keys :)
Re: Show HN: Olelo Foil - NACA Airfoil Sim
#14Unless you're planning to resolve the boundary layer and model separation (good luck...), you'd probably be better off using panel methods than NS. Look at XFoil or JavaFoil for available implementations.
Also, it looks like you might have a bug in generating the airfoil shape. An airfoil like the 8412, while extreme, is well-defined and constructible from NACA-style combination of thickness and camber forms; but you show it as having a "kink" on the bottom surface, which is definitely not correct.
Good catch - I'll look into fixing this. thanks!
Re: Show HN: Olelo Foil - NACA Airfoil Sim
#15Figure I'd drop this here - some other projects I'm working on currently:
Seafloor LOD (infinite terrain generator): https://github.com/kanakawai-maui/seafloor-lod
Olelo Honua (free LLM-enabled translation tool): https://www.olelohonua.com/
Re: Show HN: Olelo Foil - NACA Airfoil Sim
#16Earlier quoted context omitted.
Also, it looks like you might have a bug in generating the airfoil shape. An airfoil like the 8412, while extreme, is well-defined and constructible from NACA-style combination of thickness and camber forms; but you show it as having a "kink" on the bottom surface, which is definitely not correct.
841220 is interesting, if you want to see what a borg cube aerodynamics might look like.
841220 is, sadly, not a legal NACA airfoil designator.
There are three major families of procedurally-defined NACA airfoils -- four-digit like the 2412, five-digit like the 23012, and the 6-series like the 64A012.
It looks like this site only expects the four-digit form, and is mis-parsing anything other than that -- which is a pity, because one of the uses of a tool like this is to get a sense of /why/ the 23012 is similar CLmax to the 2412, but with lower moment and a more sudden stall. If nothing else, input validation is necessary!
Re: Show HN: Olelo Foil - NACA Airfoil Sim
#17Earlier quoted context omitted.
Also, it looks like you might have a bug in generating the airfoil shape. An airfoil like the 8412, while extreme, is well-defined and constructible from NACA-style combination of thickness and camber forms; but you show it as having a "kink" on the bottom surface, which is definitely not correct.
Good catch - I'll look into fixing this. thanks!
Yep. If you're generating them yourself, you'll probably want to be careful to follow the NACA method for combining camber and thickness profiles -- basically, running a circle of thickness-profile-defined diameter along the camber line and unioning the areas. The alternative (which is these days sometimes called the Riblett approach) is just to define the airfoil as the camber line plus or minus half the thickness vertically at each point -- which often leads to better airfoils for many purposes, but will disagree with available NACA data, especially w.r.t. nose radius (and thus, critical angle for airfoils which stall near the nose).
If the goal is to allow a user to compare the properties of different airfoils, there's a lot to get right to make sure they actually know what airfoils they're comparing. The alternative is to allow airfoil selection from one of these sites [1][2], which also allow a link to provide comparative analysis.
[1] https://m-selig.ae.illinois.edu/ads/coord_database.html [2] https://bigfoil.com/
Re: Show HN: Olelo Foil - NACA Airfoil Sim
#18Earlier quoted context omitted.
841220 is interesting, if you want to see what a borg cube aerodynamics might look like.
841220 is, sadly, not a legal NACA airfoil designator. There are three major families of procedurally-defined NACA airfoils -- four-digit like the 2412, five-digit like the 23012, and the 6-series like the 64A012. It looks like this site only expects the four-digit form, and is mis-parsing anything other than that -- which is a pity, because one of the uses of a tool like this is to get a sense of /why/ the 23012 is…
Added validation and looking into fully supporting the 5 digit codes - thanks for the feedback!
Re: Show HN: Olelo Foil - NACA Airfoil Sim
#19Unless you're planning to resolve the boundary layer and model separation (good luck...), you'd probably be better off using panel methods than NS. Look at XFoil or JavaFoil for available implementations.
Also, it looks like you might have a bug in generating the airfoil shape. An airfoil like the 8412, while extreme, is well-defined and constructible from NACA-style combination of thickness and camber forms; but you show it as having a "kink" on the bottom surface, which is definitely not correct.
I may have fixed 8412 :)
Re: Show HN: Olelo Foil - NACA Airfoil Sim
#20This is very fun - here's a small feature request: add the ability to define KFM airfoils.
https://en.wikipedia.org/wiki/Kline–Fogleman_airfoil
I experiment with these airfoil designs and it would be very nice to have a smooth way to see the various efficiencies/inefficiencies of various dimensions of KFM airfoil.