MIRO 2

[CSpaced]

I used the roller when I repaired my composite edge, it worked really well and it was much easier to apply an even coating of epoxy. I never thought about rolling off the excess onto a paper towel - good tip!

[Rod]

Im doing wing skins now.
First trued the edges with the edge sander. I have always used a straight edge and knife but I have found the sander a bit better as the blade has a tendency to follow the grain rather than the straight edge.

[Rod]

Join enough balsa for 2 skins minus the leading edge (or trailing edge) sheet. Tape lightly on one side and turn over and fully tape the other side. This side should become the outside as there will be less glue on the surrounding wood.

[Rod]

Turn back over and remove the small pieces off tape. Then hang over the table edge to expose the edge so the glue can be applied. Use aliphatic and apply with a small squeeze bottle. Cut a little nick in the spout so you can use it as a guide on the edge of the wood. You can then apply a bead of glue in one smooth motion (you can see from the motion blur that I do this operation very quickly).

[Rod]

Once all the glue joints are done and the sheets are back flat on the table glue should squeeze out of the joins. Remove this carefully to avoid spreading the glue around as much as possible. I use a thin piece of plastic to scrape it up. Gently wipe as much glue off the joins with a paper towel. Leave for 15 minutes or so then sand the joints with fineish sand paper say 320 grit. The idea is to get sanding dust into the glue joint and fill any gaps. Leave for 45 minutes or so the turn over and remove the tape. Do the same again with the sand paper. Dont forget to mark the inside of the sheet. Cut the sheet in half on the diagonal and glue on the leading edge. Remember to cut one sheet on the diagonal one way and the other sheet on the diagonal the other way. Think about it. So you get 2 pairs with inside the right way round. Weight of 4 skins is 195gms bare and 202gms with dope

[Rod]

Weren't happy with the wing cores so I got some SL (superlight) foam from my local supplier. New cores are 89gms each as opposed to 100 gms for the earlier ones

[Imac Kiwi]

Looking good Rod, now all you need is a YS 170 powerhouse to pull that puppy!!

[Rod]

Hi Alan
No 170, but have the next best thing a YS 160 with short Hatori muffler.

[Rod]

Haven't been happy with my mold release system. It works OK as long as I put plenty of PVA release on, but I have been experimenting with the Zyvec system from Fibreglass supplies and it works really well. So I have stripped the fuse mold and applied the Zyvec sealer and release.

[Rod]

Cores are ready for bagging. Changes will be lighter glass reinforcement (75gm glass) well towelled off. And lighter weight carbon uni spar. I wont need to sand a groove for the carbon.

[Rod]

Out of the bag and the weight is 234gms. 26gms lighter than the original wing panel.

[brusty]

Hi Rod, Very interesting post, its good to hear how others approach the same ends. I have recently completed a composite moulded scratch 2.800 meter Turbo Raven, and like you, have changed to using 12kg white foam for the cores. It certainly saved quite a bit of weight, but gave me some grief with crushing, especially as I used 1.5mm divinicell as the skin. I found it necessary to fit temporary hard balsa root and tip ribs to stop the ends crushing, and kept the pressure at about 8 ins. The only problem then was that the bond became a little suspect, I used epoxy wetted out 1.5 ounce cloth as the adhesive to form the inner layer of the laminate. When applying the outer layers of cloth 2x 2.3 ounce, I was able to lift the pressure up to 10 to 12 lbs.

In the light of this experience, for all the saving, I think i would stay with the 16kg foam next time, and just hotwire a bit more out of the finished wing. I am also considering applying the skins with Gorrilla glue, I did a test sample, and there was little difference in weight, and the penetration and adhesion of the polyeurathane glue was excellent. Then the ouside i might use a layer of 2.3 ounce and a layer of 0.75 under the mylars. What are you thoughts?

Regards, Barrie.