madyottie 82 Posted November 23, 2019 Share Posted November 23, 2019 Hi all, I'm trying to locate an article on foil shapes from Australian Sailing magazine, February 1998, about foil sections, by a guy called Neil Pollock. Following an awesome little regatta last weekend, I find myself in need of another rudder, this time complete and near indestructible. Evidently I needed much more glass near the stock. Pollock's article was a then-new formula for calculating shapes for flat sided foils, which had proven to be better than the NACA sections. If anyone has a copy, I'd really like to steal it. Quote Link to post Share on other sites
MartinRF 53 Posted November 23, 2019 Share Posted November 23, 2019 Does this help even if it is not the article you are looking for? http://www.boat-links.com/foils.html Added 11 h later: Why do you need flat-sided foils? Class rule? Beating my own drum (yes, about dagger boards but still true for rudder blades): http://hem.bredband.net/b262106/pages/daggers/index.html /Martin Quote Link to post Share on other sites
madyottie 82 Posted November 26, 2019 Author Share Posted November 26, 2019 Sorry for the delayed response, big days! Moving on... Pollock did a huge amount of practical testing and found what seemed to be the best section for stall resistance, drag etc had flat sides, which went against all previous research. From memory, his initial idea was for 470 foils, which require flat sides with limited shaping. Again from memory, he then went on to high performance boats and found the flat sides outperformed the NACA 00xx sections. He also coined Pollock's law... If practice conflicts with theory, theory is wrong. Not an actual law, but still something I tend to utilise. Moving on further... I recently built a super light rudderblade for my Noelex 22, about 25-30-45% le/flat/te which balanced and gripped well but due to the limitations of the rudder stock, and me not having time or sense, was way underbuilt and snapped off in a prestart. Since I'm starting again, I thought I should try to find the formula's and put some real effort in, as well as some carbon. If I can't find the article, I'll try to replicate the broken one, but stronger. Then I'll build a stock to match. Quote Link to post Share on other sites
crump 2 Posted November 27, 2019 Share Posted November 27, 2019 There's a bit of a related topic over here where I'm trying to dig up any info I can on designs that worked well for a D28 boat. If you have any suggestions there it would be appreciated to! http://crew.org.nz/forum/index.php/topic/17300-davidson-28-rudder-lore/ Quote Link to post Share on other sites
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