04-14-2007, 02:10 AM
I wanted to build an electric F4f wildcat out of eps foam. I was planning on making a 3 channel bird. Any suggestions on where to get plans for the wildcat. And also how do you find out what postion you mount a motor on an rc plane with all the things that go along with motor mounting.Plus what is the easiest way to calculate your center of gravity. Can I just weigh everything and draw it out? Any help would be appreciated. Also what is the best paint to use on foam. I dont want a bright pink wildcat.
05-04-2007, 11:43 PM
The AMA web site should have plans available for you on that one: http://www.modelaircraft.org/
The white beaded foam is eps, the pink is polystyrene and is heavier and not my first choice to work with, stick with the eps and it will be light.
Along mounting the gear, look to what is already working mainstream, there is no one way that works on all designs accross the board and you should be able to find the plans/specs for the full size bird which will be similar. I'll take for example one plane that there is some debate over the COG, it has a 7" deep wingspan and the reccomended cog mark is 2", yet I found 1.5" to be a much better fit, especially since I'm powering it up with brushless/lipo, yet the original is based upon nimh and brushed so a large difference in power to weight ratio.
Krylon H20 is a good paint to go with if you are looking for something out of the can, acrylics are also a readily available choice that won't harm the foam. Felt pen can also be used if you are wanting to be weight concience about it all, or if you are using eps, a couple of colored strips of tape will do the job for orientation sakes.
I'll also throw in a few more tips, packing tape really helps strengthen up the structure, many people will tell you to use the 3m 777 on the foam prior to laying down the tape, 3m 777 melts the foam guys and is NOT reccomended to use at all, Wilsonart h20 is an excellent contact cement that's water based if you require something to lay down on the foam prior to adding packing tape, but if you properly press down on the tape as you apply it, it shouldn't lift up off of the foam. Ultracoat is another option, but I'm not a huge fan of that for foam, it tends to contort the structure as it shrinks and you do risk melting the foam since it's heat activated not to mention the weight added. If you spackle it, do so very, very sparingly, it will significantly weight the plane down if you are going for perfection in that area.
That said, I found building in modular fashion aids in overall strength, for example, if you build a rudder, encase it in packing tape and do the same with the fuse, when you attach the two together, you are only glueing tape to tape, this provides a superior bond, and especially if you are using hot glue, instead of having to fix broken foam, you are simply reattaching the modules back together should you crash it. This also helps when you are mounting a firewall, once it's glued in place, you can even add another layer of packing tape over it to improve it's strength significantly.
I hope this info helps, good luck with the project!
05-04-2007, 11:49 PM
Thanks a lot. Yeah I have to buy another 3 channel or 4-ch radio. So this project will not be fast going
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