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Old Nov 04, 2013, 08:59 AM
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Build of 1.2M (47.25") Foiling Cat

I am using the plans from Chris in Germany with modification's we have discussed. the plans are available FREE here;

http://modelmultis.wordpress.com/get-one/kampai-mini40/

Chris built in 2010 and his build is here;

http://www.rc-network.de/forum/showt...ghlight=Kampai

I decided to start with the foils and after months of research have decided to start with T foils with the Bradford height controls shown below to not only lift the hulls but provide Righting Moment also to help prevent capsize and pitch poling.

https://docs.google.com/viewer?a=v&p...NmI0ZDFmOGM2ZA

I have used naca 0010 and 0008 for the lifting and daggerboard+rudder. Info here;

http://airfoiltools.com/search/index...D=5&yt0=Search

Click on airfoil details, then on that page Reynolds Numbers, then on that page enter your span in meters, speed and down further click on 68 degree water. You will then the efficiency of that foil in water.

I ordered foam cores because I have never been able to hand sand a plug with the tolerance required for this small of a foil and it was MUCH faster to mold.

https://www.flyingfoam.com/

I used their Quick Order EPP cores so I could bend it more than 90 degrees for an L foil down the road. It bends around a 3/4" rod with no problem. But it is a bear to work with, huge holes and very floppy, I spent several weeks filling the holes with spackling compound after spraying them with black paint to ensure I did not sand too far and making sure the were straight.
Next time I will use their EPS or better yet their 25# which has a much finer texture. In Fact I may use that for my wing sail patterns.

Foil molds are done and fiberglass has been infused as a mold test and came out very well.

Currently working on center pod plug and hull plug, both should be done this week.

If your wondering what started this project

Replay: AMERICA'S CUP FINAL - RACE 19 (2 hr 38 min 34 sec)

race starts at 10 minutes.
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Last edited by JIM CALDWELLA; Nov 19, 2013 at 07:44 PM.
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Old Nov 04, 2013, 09:28 AM
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Jim,

Are you planning a single central rudder like Chris, or twin T-foil rudders?

Jim.
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Old Nov 04, 2013, 09:08 PM
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Single rudder.
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Old Nov 05, 2013, 01:36 AM
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T-foil?
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Old Nov 05, 2013, 07:56 AM
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T foil just like the lifting foils, all foils with Bradford System including rudder to help prevent pitch pole I hope.
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Old Nov 05, 2013, 08:43 PM
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Quote:
Originally Posted by JIM CALDWELLA View Post
T foil just like the lifting foils, all foils with Bradford System including rudder to help prevent pitch pole I hope.
========
You're going to use a wand on the rudder foil? What will the set-up be for the angle of incidence of the main foils and rudder foil?
Great project....
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Old Nov 06, 2013, 06:58 AM
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I am not going to use a flap I am going to change the angle of the foil so the incidence will be self adjusting.
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Old Nov 08, 2013, 07:33 PM
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Her are some pic's the infusion of the foil mold test. I was going to take pictures of the infusion but it happened in seconds. Second photo is the start of peel ply tear off.You can see from the last photo I almost shut the resin off too early.
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Old Nov 10, 2013, 03:44 AM
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Rudder with winglets

Jim,

Have you seen this thread of Claudio's? Looks like a neat mechanism for controlling the angle of a T-foil.

Jim.
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Old Nov 10, 2013, 06:28 AM
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Thanks Jim, I had not seen that. but my solution is very similar to the last picture only the uprights on the rudder post will hold the bellcrank for the 440 control rods.
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Old Nov 13, 2013, 07:50 AM
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Center pod.
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Old Nov 16, 2013, 10:01 PM
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Originally Posted by JIM CALDWELLA View Post
T foil just like the lifting foils, all foils with Bradford System including rudder to help prevent pitch pole I hope.
Jim C,

This is just a guess, but I wonder if you are going to run into longitudinal stability problems with both the main foils and rudder foil self adjusting? I'm imagining some sort of feedback instability.

Jim.
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Old Nov 17, 2013, 06:49 AM
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That's a possibility, but different spring rate's should take care of that. Stronger on the main foils for early lift off, lighter on the rudder should change the cycle rate.
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Old Nov 17, 2013, 07:03 AM
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That's a possibility, but different spring rate's should take care of that. Stronger on the main foils for early lift off, lighter on the rudder should change the cycle rate.
Crosswise instability.

Yes, I can see that different spring rates is a good approach.
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Old Nov 17, 2013, 07:35 AM
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Hull plug;
I used 3m 77 to stick the packing tape covered templates to the press board material I used for stations then hot glued the foam between the stations. When I cut the plug off the board the top of some of the templates had disappeared so I had to dig down in the foam to reestablish the lines, then cut foam pieces to fit and fill with spackling compound a reshape. I should have used a stronger glue for the templates.
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Last edited by JIM CALDWELLA; Nov 17, 2013 at 07:43 AM.
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