Vunderfoil

[burchas]

As mentioned in the OP we can now hot swap sections (downloads, scans, tweens, morphs, banana) and export to all common file types, so if we have software we can simulate.  I put in a ticket with Autodesk regarding their CFD.  It appears to be windows only??  but I still have a windows machine here if needed:).  Fusion has built in simulation features which are excellent but not applicable for wind or fluid.  I found a Fusion app store extension but it is goofy.  Fusion has a simulation extension https://www.autodesk.com/products/fusion-360/simulation-extension?term=1-YEAR&tab=subscription , which I now want for other uses but it doesn't do wind or fluid AFAICT.  I see them moving towards a unified cloud based platform for everything (which is what Fusion 360 is becoming) so hopefully the CFD will become tightly integrated soon.  I know that I would spring for the simulation extension pack if this were there.  Here is there CFD.  It looks extremely fiddly, even by Autodesk standards and I think it would be a great job for Bill.  Hah!

Admin, how did you go about choosing Fusion-360 as your tool for this endeavor?
Reading through your challenges it sounds like Rhino3D offer a path with less resistance:

- Widely used in the Marine world (including America’s Cup)
- Good community support on that segment
- Mac compatible
- Nemo plugin for everything marine design including Hydrofoils
- A selection of CFD plugins
- Pay to own license rather then a blood sucking subscription model

Hope that helps

[jondrums]

These guys do a lot of computer analysis. Might be able to get some tips from them. This is the only thing I could find of it with an easy search. The designer has posted on other forums talking about it though.

https://www.indefoil.com/foildesign/mast-thickness-drag

I happen to know for a fact that the fellow designing INDE foils is using XFLR5, which is a front end for XFOIL CFD codebase to analyze not just the foil section but the entire mast, fuse, wing and tail

[Admin]

These guys do a lot of computer analysis. Might be able to get some tips from them. This is the only thing I could find of it with an easy search. The designer has posted on other forums talking about it though.

https://www.indefoil.com/foildesign/mast-thickness-drag

I happen to know for a fact that the fellow designing INDE foils is using XFLR5, which is a front end for XFOIL CFD codebase to analyze not just the foil section but the entire mast, fuse, wing and tail

Thanks Jon, I really appreciate the suggestion.  This will be fun to use.  I did some searching and it appears (where full wings are involved) that XFLR5 acts as the wing creation tool.  It looks like it is primarily allows for basic extruded or surfaced sections or joined sections created this way at angles.  We already have data for thousands of existing sections and for straight extrusions of those sections.  That is where our section choice is currently beginning (along with what is already known to be in use).  I am not finding any example of flowing curve structures like we use for our foiling sports or any way to create that in this software.  I am also not finding any way to import our outside created structure (or grouped structures, which is really where we need to be).  Maybe that functionality exists but Google and the support docs are not readily clear on that.

Wings with our flowing 3D curves are actually very challenging to create and control in software while maintaining section integrity.  You have to use a different tool path (other than simple extrusion or surfacing).  What he  does in this video (essentially import two dat section files and then straight surface them) can't be used to create our wings.  Neither can the next two easiest tool paths in outside CAD software.   He is using one section for the wingtips and another for the root so he essentially has infinitesimal sections in between.  I wonder what Inde is using this for.

[Admin]

Admin, how did you go about choosing Fusion-360 as your tool for this endeavor?


Hope that helps

Thanks burchas, it all helps!

We use Fusion 360 at work for product design, so we are already paying for it
 
I like to gripe about it, but it is also amazing.  I will check out Rhino for sure.  It looks like we can import our files for use with their plug ins.  That would be really cool.

[tarquin]

Messaged a couple of friends and they both said the same thing.
 If you can copy something accurately that works do it.
 Then decide what you want to change.
 That's when it gets difficult. You can't just make a foil longer or shorter etc. You have to change the chord.  Don't waste money on CFD until you really know what you are doing and get the most out of it as well. So I was wrong there.
 So in general it looks like you are on the right track.
 Then the build is important. No point spending a fortune designing something that flexes or twists. Again you are on it .

[Admin]

Messaged a couple of friends and they both said the same thing.
 If you can copy something accurately that works do it.
 Then decide what you want to change.
 That's when it gets difficult. You can't just make a foil longer or shorter etc. You have to change the chord.  Don't waste money on CFD until you really know what you are doing and get the most out of it as well. So I was wrong there.
 So in general it looks like you are on the right track.
 Then the build is important. No point spending a fortune designing something that flexes or twists. Again you are on it .

Thanks Tarquin,
I really appreciate it.  It sounds like you have a group of sailors at he forefront of sail foiling there.  Those guys (AC and similar) are on their own in designing foiling gear.  I am amazed by what they have accomplished.  The more I dig in to this the more I realize how unique our foiling actually is.  Our center of gravity is in constant motion, pumping very unique, and each discipline is its own design sphere.  I will look at a CFD but I expect a steep learning curve there as well.  Garbage in...

[Admin]

This is a 425 that I worked up this morning in Fusion.  Sadly, I can't print it in a single piece, so I cut it up a bit for easier and more accurate gluing before it goes to prepreg.  I can hear it printing in the background in PA-CF 🙂.   I did a 360 yesterday in a single piece that weighs 36 grams and is rideable as is.  For the larger front wings I am going to keyhole the joints so they slide-lock together during gluing and before prepreg.

[Admin]

Here is the freshly printed core, just out of the printer still up on supports.

[PonoBill]

Well, I made an eyeglasses case and a hinged box, so I've caught back up to about where I was three years ago.

[Admin]

Well, I made an eyeglasses case and a hinged box, so I've caught back up to about where I was three years ago.

This is actually a terrible time for you to be stuck over there in Bora Bora.  Enough basking already, I need you back in the USA, and quick.  We have foils to build and I have a zillion questions for you.

This little magic Bambu box that you suggested is outrageous.  I love it.  Possibly to an unhealthy level.  Still working on best settings, and of course the actual prints have pointed out spots where I need to improve the files.  2 steps forward, 1 st...or is it... 

Right now I have set the pedestal max width at a diminutive 12 mm in preparation for your blade fuselage.  Please send me a sketch of what you have in mind for that.  Flex is really uncharted territory for our sports but It is really interesting.  The effects of wingtip flex on vortices is fascinating.  It seems like the current thinking is flex=bad but that doesn't seem universally true for all component parts and may offer great benefits if well considered. 

This whole project has my mind lit up.  I love that feeling.  I finally have given in to Fusion 360's parametric timeline (which I have always dreaded).  The ability to change things in the past and have those changes alter all downstream changes is trippy in itself but it used to blow me up in a lot of scenarios.  now, with AI (deep learning, whatever we call it now) it intuits my desired result remarkably well. So freaking cool. 

[PonoBill]

Yeah, I reset my Fusion 360 skill level to less than zero when I wandered off to do electronic stuff two years ago, but the key to Fusion is parametric design. The first thing I do is figure out the parameters, including any offset for designing multiple parts. Using a construction line with a specific dependent length parameter (like length *.1 of the first part) to create points that you can use as constraints keeps parts from colliding when you make them bigger. You don't need to know the values, though you need to plug in a guess. Another key is deciding which parameters are dependent (can be calculated from other parameters). And then setting constraints as you draw. You've obviously figured a lot of this out, but defining parameters is a huge timesaving. It all but eliminates having start all over when you fucked something up. Especially when, as you point out, you go back in the timeline to rework something. Or just change parameters to change the scale.

I need to pick an effort and stick with it. I'm relearning Fusion 360 at the same time that I'm trying to make InfluxB (a time-series database) work with my Node-red and MQQT embedded systems projects. And I'm replacing the microinverters in my PV power system, and of course, getting in the water as much as possible.

I have to admit, I feel a bit constrained here in Bora-Bora, and I'm not really going to be unhappy to leave early so Diane can get her knees replaced. I've gone so far as to suggest she move up the schedule. This stuff is fairly thrilling. The entire print-to-ride concept is nuts but doable.

The fuselage I've been envisioning is pretty simple--slender bars in either a T or 90-degree X cross-section with the edges tapered to decrease drag. I thought we'd be building it up from carbon bar stock, but we could certainly try printing it. If that doesn't work it could be easily molded, either prepreg or carbon forging. The T would be easy to tune for horizontal and vertical flex, and X would add torque tuning.  Your plugin wing idea would work well with both, though I think that might be more suitable for the tail and look for a way to plug the fuselage into the front wing directly into whatever added wing structure holds the mast. Probably just a bulge like I think you were considering for the mast location for the Axis advanced fuselage.

Yeah, the Bambu Labs printer is remarkable. I'm stuck here with a funky old Prusa printer that feels like an old flip phone compared to an iPhone. The core tech still works, but that's all.

Oh, and flex is inevitable. The earth flexes when we walk on it. The distance is probably around a planck length, but when you apply a force everything flexes. Theoretical bullshit aside, I think what we need to do is decide where and how the flex occurs. Obviously aircraft wing designers have to include flex in their designs, anyone with a window seat in a commercial jet has seen that. The difference is just scale.

[PonoBill]

I just showed Diane your work. She compared it to my eyeglass case and gave me a special olympics hug.

[Chan]

I have to admit, I feel a bit constrained here in Bora-Bora, and I'm not really going to be unhappy to leave early so Diane can get her knees replaced. I've gone so far as to suggest she move up the schedule. This stuff is fairly thrilling.

I just picked up the Winter issue of the gorge magazine featuring an article on Winter SUP which has a classic picture of of you leaning in to check out the weather forecast up on the monitor at Big Winds, taken by the multi-talented Jennifer Gulizia (see pg 41).

[PonoBill]

You may have seen this video, I doubt you'll be printing multi-color santas but the ability to control up to 16 filament choices automatically and precisely select where each will be used in the slicer is simply insane. I'm wrestling with getting a Babu Labs printer for Maui. It's silly to do that, but what the fuck. Some of the stuff I print has extensive support. Using something like Polycarbonate for support guarantees you'll spend a lot of time with an exacto and sandpaper. Printing support filament, either breakaway or soluble, is an incredible feature. For that matter switching out filaments to take advantage of other mechanical properties would be interesting.

For anyone wondering why the Bambu Labs printer is so exciting when they can print perfectly well with their 200-buck Creality Ender, take a look at the level of tech in this printer. Fucking amazing. I'm surprised that the general 3D print world isn't going nuts over this, but I know a lot of people have spent a lot of time optimizing what they have. It's a Ford 1990 F150 vs Cybertruck.

[Admin]

Here is a reverse engineer of an Axis tail to get the pedestal right for tails.  I started with a scan, matched the profile and outline and tugged a little.  I will set the height and incidence  and then run the top contours off of each individual foil so, this will act as our start template.  I printed this draft with super light infill (essentially hollow) in PA-CF, but even so, there is no way I can flex it by hand.  Ooooh! my tenderloin is done!
Happy X-mas guys!