THAT was a long time ago ... I started playing with CFD and must admit it's quite some work, but fun ! After fiddling with 3D, I am now playing with XFOIL, to compare some foil shapes.
I put up a little excel sheet to transform the xfoil variables into somthing standard. I also read on the net that the Ncrit variable should be put to around 3 to have a water behaviour of the turbulence. If you have any other advice, I'm interested of coarse.
Meanwhile, I'm nearly done installing a little room where I hope I'll be playing around with epoxy soon. We saw a very usefull Youtube vid http://www.youtube.com/watch?v=mROBlWIu8q4 of the beaver hull bluiding and it opened my eyes a bit. I'll have to build a team too and we'll probably just copy all the rest... One thing I didn't understand is why they put a layer of aramid under the nomex ; you know ?
Stay tuned, post a comment, happy christmas.
Hi,
ReplyDeletefalls nicht bekannt:
http:// xflr5.sourgrforce.net/xflr5.htm
Ist viel komfortabler
Gruß Chris
I'm one of the guys in the YouTube video. The idea with the Kevlar layer was to help keep the water out and to toughen the thin carbon skin. We used 5.7oz/sq yard carbon cloth. With one layer there are thousands of pin holes that take a lot of filling just to keep the water out of the boat. The Kevlar was 1.7oz/sq yard and has very tight weave; more efficient than lots of epoxy and filler.
ReplyDeleteJohnz, thanks for this nice video. I think you could have made plenty of small nail holes (1 or 2 psqin) in your Nomex core so that the excess resin of outer/underneath skin could be sucked up/through those holes by inner/above bleeder mat. This is how kiteboards are made. Just my 2c.
ReplyDeleteHi,
ReplyDeleteNcrit = 3 should be ok. I did some research on the purpose and values of Ncrit for my own XFOIL simulations. It's a value to set the initial disturbance causing turbulence. According to a paper, the MIT's water tunnel Ncrit = 2.623.