hello, i don't know if the latest thinking is any different than 60-90's thinking, but here is a link to a foil that would work pretty well for a rudder. http://marlongofast.tripod.com/zipped_aeronotes/NACAfoil.htm 6% may be a hair thin, but a naca63 series foil will be good for rudder and board. keep in mind that hand shaping may not yield a perfect replica of whatever foil you are trying to shape. if you find the ultimate foil to replicate you would need to use a cnc machine to create it if you want valid test results for that particular foil. you can make templates for the foil you choose to check a hand shaped blade.
NACA 12. from what i've learned on the subject. this is a good basic profile. i used www.flyingfoam.com Bob there was a very nice and the price was right. maybe check with hobie as to what there foil is so they match the wells. i had Bob cut the cores. this is for a dagger board. as for rudders a naca 12 s/b close. maybe something slightly thicker/shorter chord. let the pro's chime in but i belive naca 12 is what is used on the inter 20 daggers. the rudders are a much more complex foil
The naca 63 and 64 series are becoming more popular, especially for higher speed sailing boats.
If you can't be bothered putting a somewhat tricky concave section in, as the 63 or 64 series sections do, the 12 series is more than appropriate.
Profile wise, parallel for most of the length with tapered tips. The tips are pretty much up to your preference as there are a lot of different theories about.
The original H20 daggerboard shape was hand crafted by Phil Edwards. The rudders are certainly quite different than the daggers. We are expecting to be given the go ahead to race the 20 with the same blade as on most other Hobies, so the EPO2 will be a good choice. They work very well on the 20. We can not offer any help on either foils specs / dimensions. There are no "plans" on them. Both are readily available for purchase, so if this is a "project"... have fun with it and let us know what you ended up with.
It's probably of little use, but I'm using a 63-010 NACA foil section for our US1meter keel (www.teamseacats.com). This is the section I really want but may have to go a tad bit thicker (perhaps to a -015) in order to get the structure needed inside the keel. I'm working out the details of the lead bulb/keel/hull structure on the computer for the next couple of weeks. The 63 series is a good all-round lifting foil with a good average between drag and high-ish stall angle....though I wonder if sacrificing a little drag in return for a high stall angle is really that important on a daggerboard.
Typically you start with a complicated formula or x&y coordinates to draw the foil. I've got the 63 series setup in a 3-D design table such that I can change any parameter (including the % of thickness). How long and what thickness do you want (10% is pretty standard)? I'll be glad to give you a 1:1 drawing.
Jake Kohl
Re: Foil Profile
[Re: Jake]
#100343 03/16/0707:41 AM03/16/0707:41 AM
Setting it up in a spreadsheet and printing the outline for a chord of 290mm is relatively trivial, if you dont want to wait until monday. Are you going to use the 63-008 as daggerboards?
Yes thats possibly going to be the plan, I have on good authority from someone you and I both know Rolf that 8% would be fine, although he was thinking 0008 series section, but I've drawn it out and looked at factory boards and they look nothing alike, so I thought I'd compare them to the 63008 section and see what they look like.
I have a set of timber boards that should do the job for starters but once I've gotten the shape worked out, I'm planning to make a mould and my own boards.
Regards
Matt Harper
Homebuilt Taipan 4.9
AUS 329 'GOT WOOD' SEEDY PIRATES RACING TEAM
Yes thats possibly going to be the plan, I have on good authority from someone you and I both know Rolf that 8% would be fine, although he was thinking 0008 series section, but I've drawn it out and looked at factory boards and they look nothing alike, so I thought I'd compare them to the 63008 section and see what they look like.
I have a set of timber boards that should do the job for starters but once I've gotten the shape worked out, I'm planning to make a mould and my own boards.
Regards
Attached at 2:1...I could almost make this 1:1 and fit...however, watch your paper sizes, this is the US 8.5" X 11" sheet size.
Jake Kohl
Re: Foil Profile
[Re: Jake]
#100353 03/20/0701:29 AM03/20/0701:29 AM
Thanks for that, I think I would have been able to take 1:1, I'm not much with computers, but I'll have a play later and see if I can enlarge it. The drawing I mean <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />
Regards
Matt Harper
Homebuilt Taipan 4.9
AUS 329 'GOT WOOD' SEEDY PIRATES RACING TEAM