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High aspect ratios I have compared probably the simplest Savitsky equation to the high aspect ratio calculation in Fluid-Dynamic Drag by S. F. Hoener. I found that somewhere before an aspect ratio of 5 the Savitsky calculation gave a higher lift coefficient than airfoil theory would give for...

Just sail on the internet.

foil modification I've been messing with foil modification at the design tab in JavaFoil. It seems easy to use, once I figured it out, but maybe doesn't do everything I was hoping. I was able to take a 2 element combination and modify element 1, while the software kept track of the...

not trash My most memorable encounter with stuff in the water wasn't trash. It was on a 36 lead mine on Long Island Sound. It must have been memorable too, since this was around 1971. We were sailing along in a race, under spinnaker I think, when all of a sudden we started braking to a stop...

Trash It's not just trash that's a problem. Some lakes get covered with algae every summer and I don't think anything can sail. I think I have heard that Volvo Ocean racers have hit and injured whales. Similar to a Manta ray and a moth, but is the problem the hydrofoil, or just that...

insanity A slightly tweaked definition of insanity is to post the same thing over and over and expect different results. I'll add a definition of abuse, which is to post the same thing over and over with no expectation of change...

For these plots the gap between elements was opened up to 5 units and the pivot was moved to the leading edge of the flap. The drag at high CL is better, but also the performance is smoother, so that pitching of the boat or small changes in trim won't cause sharp changes in results.

1st plots I' going to do two posts. In each the mast and flap are both 50 units wide and the flap is deflected 20 degrees. In this post the undeflected gap between the two is 1 unit and the flap pivot is 45 units from the mast leading edge. The main thing I don't like is the big jump in...

Sounds good to me. A Z on the sail would work.

foil tips Rick, I will have to play some more, but I now see I wasn't paying enough attention to all the boxes on the modify page. I had been scaling and moving the two elements independently, but hadn't seen that I could change the thickness too. I'll play some more, but it does still...

Good, or bad? Rick - Thanks for the answer. I'm encouraged and discouraged. I'm encouraged because I now think I see a path to evaluating a simple 2-element wing design, but discouraged by seeing the work involved, at least in JAVAfoil. I did runs where I took 2 equal cord foils, played...

OK, another idea I hesitate to post here, since the last post was almost a day ago and letting this thread die would be the kindest act, but I had another idea and well, I couldn't resist. There is a class today where: - There has been a history of innovation including a huge step forward...

I'm messing around with JAVAfoil, specifically looking at creating simple combinations of 2 zero-camber foils. To start though I thought I'd just create a NACA 0012 foil in Excel, import it and compare it to the one that JAVAfoil creates. It looks like the spacing of points in the x...

You can't get there from here I admit that I'm repeating myself, but I don't think there is much chance of the C-class taking off. Initially the only boats you might race against only meet every couple years, if that often. A-Class actually has fleets in at least a few places in the world...

Pivoting foil It's amazing, how did you copy it from me before I wrote it?

DSS tri application The DSS does seem to have some credibility. The problem for a tri though is that you would like a relatively long foil for efficiency and it won't fit inside the hull. I think I have a solution that is an improvement for all DSS systems and also lets it work on a tri...

Unawing? Is this implying that there is/should be a gap between the sail and wing mast of a unisail, so that the two can act like a wing and separate flap? If so, it seems like it might be possible to get significantly higher lift coefficients out of a soft sail. I can imagine you might...

resources I'm actually caught up now, but it's hard to go through the posts without looking up some of the terms, and as a result I came across some interesting sites. The first is a paper on a model for sail performance. It's by Krebber-Hochkirch and extends the work of Hazen and Jackson...

wing design "No, but max diameter for the spar is only needed where stiffness must be maximized in order to avoid buckling, it can be reduced elsewhere towards the ends with no penalty in weight as far as I can see. That method would allow having max diam. structural spar halve way between the...

6m class A laser has a 20' mast height, or 6m. Something near there might be a reasonable limit for the smallest class of this type. I think though that it would become a weight watchers class. For a 6m class I imagine a very light 16' cat with an Opti sailor on a trapeze. A very...