What is prepreg carbon plate and where do you get it?

[soholingo]

Mark Drela mentions 'prepreg carbon plate' in his description of how to build a wing joiner Joiner build pdf (http://www.charlesriverrc.org/articles/allegro2m/joiner_build.pdf) . I have never heard of this nor do I know where to obtain it. Can someone tell me where to get it? Thanks

jay

[davidfee]

Prepreg carbon plate is, well, carbon plate made from prepreg carbon, rather than a wet layup which was vacuum bagged. In other words, it's not the decorative panel stuff you see the RC car and heli guys using.

Prepreg already has a slow-setting, high-temp cure epoxy "impregnated" in it. For this reason, it must generally be stored in a freezer, or on dry ice. It is usually (but not always) a unidirectional "fabric," where all the fibers run in the same direction. In most cases, prepreg will come rolled up on a plastic or wax-coated paper backer.

The immediate benefits of this are that less time can be spent doing the layup, but also the resin ratio is already much better than most humans can easily achieve. Also, with straight fibers (rather than a woven fabric) the parts will be stronger for the same weight. However, the high-temp cure epoxy means that any tooling and mold release you are using must be capable of withstanding >250F for extended periods.

You can buy prepreg from several of the online composites vendors, such as CST. They will ship it to you in a styrofoam box filled with dry ice pellets. You then have to keep it cold until you use it. You can just clamp several layers between two aluminum blocks to make your joiners. I have never seen a +/- 15 degree plate offered commercially. Normaly they are just +/- 90.

You might shoot Dr. Drela an e-mail, or make a post on one of the Yahoo groups for his designs for more specific help.

-David

[soholingo]

Dave you are the man... I don't know why I don't just call you when I have a question...

j

[davidfee]

Haha Maybe I just spend too much time online. ;)

[jofo1]

Dave you are the man... I don't know why I don't just call you when I have a question...

j
If you call him then the rest of us miss out on some learning...thx to both of you for the Q and the A.

jofo

[davidfee]

Stop... you're going to make me blush! ;)

Seriously, I am only an example of what happens when you spend several years researching composite techniques and then try some of them. I'm no expert.