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Messages - MikeLima

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31
Realistically I’ll never try the whole thing, but maybe running it through the water holding it shimmed and not might be interesting to feel….

32
During my most recent prone session I had a repeat of my most common failure: getting repeatedly launched at take off. I had forgotten the tail I’ve been using(with 1° less downforce shim): a chopped 220 kujira which is probably ~200cm2.  So instead I used a 178 with no shim, with the 1095. It was a pretty stark difference, particularly since my technique isn’t to the point where I can adapt well. Kujira foils are supposed to be front foot heavy, Armstrong not so much(I’m on an Armstrong board). So to get them to work together I’ve got the mast all the way back, the mast shimmed for less AOA, and had usually been shimming the tails, with some success.

But this experience got me to thinking about tails in a new-to-me way. From the time I first looked at a foil setup, I’d taken it as a given that the tail creates some amount of downforce. Then, while discussing his Armstrong setup with another member of our crew, he said something about a neutral tail. I was confused at the time, but now it’s dawning on me that there is a greater diversity of tail dynamics than I had previously known. So how do you quantify what a tail is doing in a standard way, since shimming a tail is only relative to the standard setting for that tail and fuselage?

My best guess so far has been to attach a fuse to a mast in such a way that the fuse is free to pivot up and down, and put it over the side of a boat with a tail and no front foil. If the fuse remains horizontal* then its a neutral tail, with varying angles showing varying behaviors of the tail. Would such a test show Armstrong staying level*, and Takuma riding tail down? It would also be neat to change tails and shims and see how all those change things…….

*actually, horizontal meaning: at the same angle that the fuse is at with a given foil, given rider weight, I guess in the middle of the foil’s speed range**? Maybe a second mast with a digital level(phone) for accurately measuring it’s angle.

**A bit of a tangent here: if a tail is neutral in the middle of a foil’s speed range, would that mean that at higher speeds, it would start to create downforce, but lift at lower speeds, because of the changing angle of the fuse? I’ve noticed kujira’s angle of incidence changes as you move outward. Would a similar shape be helpful for a tail meant to be neutral, in order to smooth out the transition from - to + lift?

Anyhoo, food for thought I guess.

33
Since I don’t know his name, I’ll call him “grey hoodie guy on jd follow cam”, he seems to be into experimenting with wing flagging, and on one recent video he has his wing leash attached to the front handle so it hovered as far over his head as the leash allowed. Since the leash isn’t that affected by waves that could be an idea?

34
So I’ve tried it a couple of times with a base shim(front), and it really settles it down to the point that I can now stand up on my board. Even with the 1210, which is supposed to have more initial lift than the 1095. Now I have to work kind of hard in small waves to get it off the water, so I might start my mast migrating forward!

35
Exactly, and yes that’s who he was talking to.

36
Pono, in your equation above, I assume foil factor means thickness or some other value based on foil section?

And concerning turning, a while back there was a discussion on the progression project about initiating turns. I don’t remember exactly what was said, but it made me watch closely, and it looks like many are yawing the board out(which can happen quickly), so their body is leaning in, and then roll the board under them through the turn. It reminds me of pushing motorcycle handles in the opposite direction that you want to go, so you can initiate the lean.

37
Classifieds / Reedin Super Wing X: 3.6 and 6M
« on: March 13, 2022, 01:56:05 PM »
The 6 has so far been used for 15 minutes or so, the 3.6 more so but in very good shape.

These are fast, and point higher than any other wings I’ve used, and it’s nice to see through the whole canopy. However, I believe they are hard to hold onto with winter gloves, so I want to sell to somebody in a warmer place. I’ve made modifications to my 4.7, which I’m keeping, that make them much better in various respects, but I thought I’d sell them in factory shape and let someone else decide on their own.  Shipping included.

6: $1,350 (new $1,500)
3.6: $1,150 (new $1,400)

38
I think you are missing that for our sport - everything we do would be considered "low speed" as far as physics is concerned.  So I really don't think we'll see speeds such that drag is reduced by going to low-aspect foils.

I’m reading the Hail Mary Project, and in it relativistic speeds are discussed, including it’s effects on time, but what was new to me was that as you decelerate, objects in front of you get farther away, despite the fact that you are approaching them at unfathomable speed. But I think this is faster than most wing foilers!

39
I have no idea, but nerding out is one of the reasons I love foiling.

Btw, what is the source for that graph?

40
To be sure, this is 99% an intellectual exercise. But, if I WERE downwinding in the middle of the ocean I’d sure as sh!t stay damn close. And if a squall came through or something else happens, then out comes the ais mob beacon, or use meshtastic. Boarding is indeed a question I’ve been pondering.

The original question still puzzles me however, as I’ve seen kayakers out in waves and they were hard to see, and go in a straight line. Seems like a thing that should exist.

41
A month back or more I dragged my 4.7 through some smallish surf and back. On the way out one wave did catch it a bit awkward. I don’t know if that’s why but when packing up after I noticed that the batten pockets were coming undone on the front on one side, back on the other. I wasn’t terribly surprised as my time as a sailmaker made be aware that abrupt changes from rigid to soft material lead to problems, which is why, for example, wires have a little rubber thing coming out of the plug with it. Otherwise you create a hinge point where all the force is concentrated. I had noticed the battens were huge when I first looked it over.

Once they were coming off I eventually decided to take them all the way off, since the warranty plan was to take it to a local sail loft anyway, and I started wondering how much of their flaccid flagging was due to the battens, enough so that I abandoned the warranty. Since it seems xply doesn’t like luffing, some battens are required, and nice and quiet, I replaced the giant ones with 12” tapered battens, depending on the pocket itself for the remaining length to the fold strip. This saves a 1/4 lb of weight at the trailing edge of the wing, and I’m sure some improvement in flagging was achieved, and the fluttering is increased but marginally.

The other issue I’ve had with the wing, especially in winter, is the narrow gap under the handle, and the angle of the handle where I want to hold it. Up front the handle is sloping away from me so it’s more like climbing a rope than grabbing a handle, if you know what I mean. Since the warranty issue was moot, I CUT THE CORE OF THE FRONT HANDLE, and created a brace with moldeable plastic, so that the handle is held away from the strut, and at a better angle. The Velcro in the handle cover holds it together just fine.


42
I get the point about sounding alarms on other’s boats given all the frequent course changes, I hadn’t thought of that. As a boat owner with an MFD that displays ais targets I can attest that would be annoying. I also emailed a boating supplier, and they said it doesn’t exist. Reprogramming an MOB beacon sounds interesting but beyond the effort I’m willing to put in. It probably wouldn’t transmit course and speed so wouldn’t trip close approach alarms.

One of the inspirations for the idea was thinking about a transatlantic trip next year, and wondering if there was any “safe” way to get some downwinding in en route. I’ve seen videos of people activating those ais beacons while out of range of any boats in the middle of the ocean. Something like this would be needed as there is no cell service for find my friends that’s for sure.

43
I’ve seen vhf handhelds that receive ais and display other boats, but not that transmit without distress.

That idea sound interesting pono, but one of my goals is to become visible to other boats too. And does it work without cellular coverage. It is true that for a group dw Apple Watches and find my friends can be handy. But other boats wouldn’t be aware without visual. In Maine that could be an issue someday.

44
I woke up wondering if a thing exists and a short search came up with nothing. Either a handheld vhf or other device that transmits an AIS signal WITHOUT sounding a distress call. So that you, out in the ocean, maybe in the fog, likely obscured by waves, show up on the screens of nearby boats. Such a thing would be handy for a lot of situations, including allowing the mothership to keep track of everyone on a downwinder. Maybe radar reflectors tucked behind the LE too…

45
You don't need the battens to be full length, or full size. They aren't tensioned. I'd probably just try short battens and keep going longer until they seem good. Kite carbon fiber rod--for actual kites--works great.

Of course! That sounds perfect!

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