Author Topic: Print to Ride  (Read 20935 times)

Admin

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Print to Ride
« on: December 24, 2022, 03:40:51 AM »
Getting pretty stoked on what is possible in a print to ride scenario.  Here is an exploded concept of a tail wing and fuselage pedestal.  The whole thing can be printed in carbon in one shot and press fit into the fuselage pedestal shown at bottom.  The carbon rod(s) can be inserted into the printed cavities to get your desired flex.  Cavities that follow the wings curves are easy to set up in software and easy to print as well.  Thanks technology!  Stock carbon rods are available in all sizes and are super cheap so no sense trying to duplicate that.


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Re: Print to Ride
« Reply #1 on: December 24, 2022, 07:38:30 AM »
These bars may be better.  The 2mm bars could go most of the wing length for a 435 wing.

https://www.rockwestcomposites.com/shop/bar-50a

PonoBill

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Re: Print to Ride
« Reply #2 on: December 24, 2022, 08:12:35 AM »
Very cool. Rockwest is a handy source, but expensive. Search for Carbon fiber kite rods and tubes. Tubes are lighter for nearly the same rigidity, rods are bulletproof. I've been buying these for years for RC model wings and quadcopter fuselages. The huge volume of these that are sold makes them dirt cheap. 10 200mmX4mm tubes for ten bucks. These are obviously the least expensive part of this effort, but still...
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

surfcowboy

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Re: Print to Ride
« Reply #3 on: December 26, 2022, 07:57:38 PM »
When you starting to print stuff? I wanna hear about the stress tests. If this works it's a game changer. I'm following this across two platforms now. Come on!! Haha

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Re: Print to Ride
« Reply #4 on: December 27, 2022, 01:05:41 AM »
When you starting to print stuff? I wanna hear about the stress tests. If this works it's a game changer. I'm following this across two platforms now. Come on!! Haha

Hah!  I have the first pocketed one set up to print when everyone is awake :).  I am convinced that we can do something really cool with an easy to print CF outer, and a pocketed stiffener or stiffeners (tops 8 bucks per tail wing).  I have a bunch of possible configurations I want to try ranging from very conventional with an insert to freakishly out there :).  That should allow us to really dial in flex as desired. 

I am not at all convinced that some well controlled flex is not beneficial, especially where active pumping is involved.  There are a bunch of related articles that I have found so far.  Interested to know more.
 https://krex.k-state.edu/dspace/handle/2097/41679
« Last Edit: December 27, 2022, 01:07:57 AM by Admin »

tarquin

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Re: Print to Ride
« Reply #5 on: December 27, 2022, 02:02:54 AM »
Awesome stuff. I agree on the flex for pumping. Even in the front wing. It must give you some help like when the tip of a paddle blade flexes and snaps back.
 Not good for going really fast though.

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Re: Print to Ride
« Reply #6 on: December 27, 2022, 04:00:50 AM »
Awesome stuff. I agree on the flex for pumping. Even in the front wing. It must give you some help like when the tip of a paddle blade flexes and snaps back.
 Not good for going really fast though.

One interesting thing that I have learned from reading is that vortices are most significant and create the most drag at low speed, high angles of attack and under heavy load.  This all screams opportunity to me.  That is basically the exact scenario of getting airborne in our sports and especially pumping, where angle of attack is steep and changing by the millisecond  under full load and at low speed.  It is somewhat counterintuitive but pretty cool when you think about it.

PonoBill

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Re: Print to Ride
« Reply #7 on: December 27, 2022, 07:56:51 AM »
I do most of my printing overnight or when I'm gone. There are some minor fire concerns, but modern printers prevent thermal runaways in various ways and are at least as safe as a coffee maker. All the same, I put my printers on a steel bench with nothing flammable around them and let them rip. Companies like Prusa have hundreds of printers running 24/7 without issue.

The load directions on the wings change substantially between low speed and high. It might be feasible to make a wing that flexes when pumping but doesn't flutter at speed.

I had a firsthand experience with lift vs. angle of attack yesterday. I was winging at Ka'a in light wind. I knew the wind would come up but I got impatient and pumped up my 7.0 CWC. That wing is tough to flip over and I didn't flip it before I got in the water so I struggled a bit to get it flipped. Once I did I had been pushed east from my usual launch spot. I got up and got up onto foil, sheeted in, accelerated, and slammed straight into the stupid bunker (there's an underwater anti-landing bunker left over from WWII). In my defense for that stupidity, yes, I know the bunker is there, but the water is brown and the tide was low. I thought I was clear--I wasn't. Anyway, I took quick look at the foil and it looked OK, so I continued out, and could not get up onto foil unless I had all my weight back on the board. Even then, I couldn't get high enough to clear the swells, which were waist-high at the reef. So I fell and fell. After a lot of flailing around, I came in over the rock garden (always fun) and had to take a blessedly short walk of shame back to my car.

It turns out that whacking the bunker put a nice ding in my front wing, but also bent the baseplate of my mast, which gave me a decidedly negative angle of attack. With all that force it's surprising that it didn't blow the tracks out of the board, but Dave Mel builds some very sturdy boards.

I took the opportunity to do some practical measurements and calculations. Looking at the alpha polar chart of the airfoil I suspect Axis is using, the -4 degree angle of attack I measured with my bent baseplate yielded a 0.0 foil coefficient. I didn't really need to use the foil equation to calculate I had about 0 pounds of lift with the board level (Yeah, I'm reading a lot of articles on wing design)

« Last Edit: December 27, 2022, 08:32:36 AM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

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Re: Print to Ride
« Reply #8 on: December 27, 2022, 09:12:46 AM »
See what happens when you're iced in.  Keeping myself entertained with this idea. I added the Axis style pedestal I did yesterday to a 450 mm tail, contoured it to match this tails size, set the incidence to -1.5, and made a through cavity/tunnel for some 2 x 16 mm unidirectional carbon bar.  This is getting printed now.  I used one section, which is pretty close to a Wortmann 9% Symmetrical section.









« Last Edit: December 27, 2022, 09:21:54 AM by Admin »

PonoBill

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Re: Print to Ride
« Reply #9 on: December 27, 2022, 10:11:31 AM »
Very cool, that should have plenty of beam stiffness. I'm going to have to look at the widths of rectangular bar available. It might be interesting to have multiple tunnels for small bars vertically oriented and use the number and location of the bars inserted for tuning the flex. That would probably be more useful with the main wings.

We'll have to either do a lot of instrumenting and underwater video for testing or find someone who is sensitive to foil performance characteristics who can articulate the differences. My sensitivity is limited to "yeah, it flew" and "no, it didn't".

The road to get down to my flow testing facility (a straight stretch of the Hood River) has actually been paved, so yay, we won't have to risk death to get down there. But it doesn't work well in the spring because of all the glacial till in the water. Visibility 0.
« Last Edit: December 27, 2022, 10:13:21 AM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

PonoBill

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Re: Print to Ride
« Reply #10 on: December 27, 2022, 10:15:14 AM »
You've probably already found tutorials as good or better, but I found this useful for understanding how to use rails: https://productdesignonline.com/fusion-360-tutorials/how-to-loft-in-fusion-360/

The most important issue mentioned is the necessity of ensuring both ends of the rail snap to the profile. If the rail won't snap he uses constraints to make them snap. I've had a lot of trouble getting the lofted surface to connect to the rail. Mine were snapped at the origin but not at the target profile. He also demonstrated the difference in the order of lofting, which I didn't understand, which resulted in some very weird shapes that might be fun to print but are otherwise useless.

The site is generally interesting. The guy is obviously a pro designer.

I also found an interesting hydrofoil foil section. Speer H105. Designed for low Reynolds number foils. There's an interesting article here: http://tspeer.com/Hydrofoils/h105/h105.htm I haven't found a .dat file for it yet but I'll keep looking.

Tom Speer designed airfoils for Boeing and was part of the Oracle AC team. There's some more info on his design on stack exchange: https://engineering.stackexchange.com/questions/36667/what-foil-profiles-does-the-mit-decavitator-or-similar-vehicle-use  That link is a good starting point for a long walk through a lot of posts. It seems Mr. Speer might give us the offsets or a data file in exchange for whatever performance data we can glean. I'm going to have to unearth the Paddle Pod, the data collection system I built for analyzing the Ke Nalu paddles. It has vibration sensors, angle detectors, a very funky load cell made from a ten-buck Chinese digital scale, and other goodies. I've come across it several times when I was searching for other stuff, but if I actually look for it, it might take more time to find than to build another. 

All this searching has led me to create a new online abbreviation: ISIDRC (I'm sure I don't recall correctly).
« Last Edit: December 27, 2022, 11:11:32 AM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

PonoBill

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Re: Print to Ride
« Reply #11 on: December 27, 2022, 11:22:40 AM »
Last but not least it occurs to me that I funded Brother Bobs (stoneaxe) CAM router because I wanted one for foil design but realized he would put it to much better use, and I could ask him to make forms for foils I wanted to build. I've never actually asked for one, but I'm sure he'd be happy to crank some out if print-to-ride turns out to be overly ambitious. He's also a top-level CAD expert--it's what he did for his career, though he seems to be allergic to parametric design since he doesn't do it for a living anymore. The router can cut molds as well as male forms. He can make that thing sing and dance. This was my Christmas present this year--a steampunk humpback.

Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

PonoBill

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Re: Print to Ride
« Reply #12 on: December 28, 2022, 04:11:41 PM »
I was talking with Mark Raaphorst this morning and he told me about a manufacturer in Hood River that makes high-end carbon sail battens using high-modulus T700 uni carbon. RBS (Robichaud Batten Systems). I'd never heard of them but Mark said the battens are unbelievably strong and stiff.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Dwight (DW)

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Re: Print to Ride
« Reply #13 on: December 28, 2022, 05:12:12 PM »
RBS (Robichaud Batten Systems). I'd never heard of them….


Not buying that one Bill. You’re having a seniors moment. haha. You most definitely know who RBS is. There were the best windsurf battens back in the day. You rig everyday right next to their building.  ;D ;D

PonoBill

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Re: Print to Ride
« Reply #14 on: December 29, 2022, 08:30:43 AM »
RBS (Robichaud Batten Systems). I'd never heard of them….


Not buying that one Bill. You’re having a seniors moment. haha. You most definitely know who RBS is. There were the best windsurf battens back in the day. You rig everyday right next to their building.  ;D ;D

Probably, but for a guy as curious as I am I can be incredibly obtuse.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

 


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