Saturday, February 21, 2009

wingtips

Ok so i have been slack. I still dont even have a mould for the new hull or even a block or foam. absolutely no progress there. the 3d file is router-ready but thats about it. Had a few projects that took over and now that theyre done im back at uni and so progress i fear will be slow. 

anyway ive been still tinkering with the blue boat - broke the gantry and it was off the water for a while and now its fixed back up again, a truly crap repair job later. one of the things i did was redistribute some area between the foils, just for the sake of an experiment. so i cut 100mm off the rudder span and added that to the centreboard, in the form of these wingtips. 

 Everyone i talk to says "wingtips are tricky, you need to do 3d analysis and work out the nature of the vortex at the design speeds etc." Anyway i pretty much ignored the advice of everone who knew what they were talking about and just designed some in rhino that looked good, cut them out, took a mould etc. I think they came up pretty good, the foil sections are pretty accurate at least. and they seem to work too, subject to a bit more testing, two things have happened; the boat launches much better and at lower speeds, and the hum that i used to have is gone. also there is no noticeable loss in stability from a smaller rudder (550 span i think) and it all feels smoother, and the boat want to go straighter. i could be kidding myself about that last bit. foiling manoeuvres were easier. also i have a new wand which i reckon is my best one so far, with a paddle about 200mm from a very flexy tip. If i do anything else i may want to extend the flap onto the wingtip, i dont seem to have quite as much response.

anyway heres a pic of my wingtip, if anyone wants one for their old and shit square foil let me know and ill make you a pair of blanks, im keen for another opinion. chord is like 115mm or so.