depron ribs and formers

svaughn · Post by **svaughn** » Thu Apr 02, 2009 7:53 am

Hi,

I'm toying with the idea of using 2mm depron instead of balsa for some of the ribs and formers of a 501 P-40 to make it lighter. I expect the ribs in the middle of the wing will need to be balsa as will the formers in the front of the plane.

Does anyone tried this or heard about someone else trying it?

Also, what do you use to glue depron to balsa?

dbcisco · Post by **dbcisco** » Thu Apr 02, 2009 4:00 pm

You need foam safe CA ("crazy") glue or Gorilla Glue. Regular Crazy Glue will melt it and most glues won't stick well. I prefer CA because it is much lighter.

For real stength area (but heavy) I use 5 minute epoxy.

I made the wings and tail for my SE5 with depron (see my thread).

svaughn · Post by **svaughn** » Thu Apr 02, 2009 8:56 pm

Thanks dbcisco,

I've seen the Gorilla glue. I think I will give that a try first.

Yes,, I saw your SE5A. Very cool. That is really what made me think of using depron.

I have heard that depron is hard to finish. That is why I'm thinking about using it for formers and ribs. They are on the inside and don't need to get a finish. Also I don't think a lot of stress is put on these parts.

Do you think the foam that McDonald hot cakes are sold in is similar to depron? How about the average foam plate?

dbcisco · Post by **dbcisco** » Thu Apr 02, 2009 9:18 pm

You are correct about the finish of foam products. I did the wings for flying and with a flat finish it looks OK. I also did an RC WWI German tank completely in depron, again flat finish isn't bad. My friend suggested covering the foam with coverlite if I need a shiny surface. Since I do electric instead of rubber power I can get away with the extra weight if needed.

I really like working with foam even though "purists" might not appreciate it.

. I will probably do the SE5 wings in traditional methods for "show" when I get tired of flying (crashing?) it. I am going to do the same for the DR1 this summer. I also have plans for a 40" completely depron DR1.

The Camel is to nicely scale and I might build it as an all balsa static only model, but that is next winter's project.

kittyfritters · Post by **kittyfritters** » Sat Apr 04, 2009 12:36 am

Gorilla Glue is a polyurathane glue that is very similar to foam insulation. In fact, when it dries, any excess glue outside the joint turns to foam and is easily sanded away. It does need clamping and is "kicked off" by moisture which is why I use it for wet laminations. Once dry it is totally waterproof. I'm not sure if it will stick to Depron. I suggest wearing vinyl gloves when working with it.

I use Uhu Creativ for styrofoam when working with foams. It is a sort of high teck rubber cement. It is available at Michael's and other craft stores.

svaughn · Post by **svaughn** » Mon Apr 06, 2009 12:07 pm

Thanks again for the input.

I purchase a fastdrying version of the Gorilla Glue (seehttp://www.gorillaglue.com/glues/fastcure/ for the 'precision glue-pen' container. It works pretty well.

I only did half the wing so far. This left wing frame (with the foam ribs) is less that 2 grams.

Also, I used foam from foam plates instead of depron from a hobby shop. This foam is about 1mm thick. It seems to be very adequate for the ribs.

I should mention, the ribs are not purely foam. I used 1/16 insq balsa between the front edge and back edge. The foam is glued to the top of this. It seems like a very workable configuration. The foam cuts very easily and the notching tool I used for balsa ribs and formers works pretty well on the foam too.

Have to get the plane done and see if it will fly.

svaughn · Post by **svaughn** » Mon Apr 06, 2009 12:09 pm

sorry. some how I didn't get the url right. It is http://www.gorillaglue.com/glues/fastcure/index.aspx

dbcisco · Post by **dbcisco** » Mon Apr 06, 2009 12:36 pm

I use meat trays (heavy and strong), poster boards (light and floppy), insulation (solid but "flakey"), packing material (variety) etc.. I have yet to "buy" any foam products.