Complex Carbon Fiber spoiler/wing

[mjalaly]

Hey so i am new to the forum and i was looking for suggestions on how to go about a new layup. As a background, i have made a handful of carbon parts so i am familiar with the process (i also know a guy who has written 3 books on it so that helps!) but i am stuck on how to go about this part.

So the hardest part is that i am trying to do it without molds since it will be one off. The rough shape of the part is 50" x 8.5" x 4" (overall height) x .500thk

My plan was as follows

1. glue together two pieces of pink foam

2. Carve and sand the top half to shape

3. layup two layers of carbon on the top half (for strength)

4. Carve the bottom once cured

5. layup two layers of carbon on the bottom

6. trim to size

7. layup a “pretty layer” for the a finished look

I am trying to avoid vacuum bagging since i would get wrinkles on the surface.

Will this work or does anyone have a better idea? Should i cut it all out at once and wrap in carbon?

[carbonBullet]

I think if you lay up one side it may warp? But with no vacuum maybe not too much. Without molds, and no vacuum. I don’t really see a different way, but thats just my opinion.

[mjalaly]

yeah i think if I was to cut the whole thing out initially, then yes, i think it may warp (especially under vacuum) but if I leave most of the material in I don’t think there will be an issue.

[fasta]

If the wing is straight?

One method I have heard of is to cut the profile from a foam block with a wire cutter.

Make sure the block is well oversize so that there will be large off cuts from the top and bottom. These are like female moulds.

Then layup the actual foam wing and wrap it with release film.

Then sandwich the wing in-between your female foam blocks and envelope vacuum bag the whole thing.

The finished part will have a release film surface that can be further finished or wrapped with a final cosmetic layer too??

[mjalaly]

yeah a straight wing would be simple… also i think with your process i need multiple pieces right? And they would need to match so that i don’t trap resin.

[Focus]

I have successfully bagged a couple of sets of glider wings that are curved. I used 60 psi foam that was cut with a hot wire for the cores. The wing halves were vacuum bagged similar to the method described here: http://www.pilotsguide.com/rc/vacbag.shtml

That website talks about using mylar that is 0.007" thick. The mylar that I use is 0.014" thick, but I was forming the wing on 9 foot radius. The mylar does resist being bent to that radius. Your wing looks like it has a tighter bend so a thinner mylar (or more flexible material) would probably be helpful.

I’ve attached a few pictures showing the finished product and the process.

I suspect that a similar process might work for your wing, but it would require some experimenting.

[fasta]

The pieces will match perfect with this method.

When the wing is cut from a block that one cut creates both the wing and the female parts from the one block with just a wire cut thickness difference. You get the wing, a top female and a bottom female. Then you are basically reassembling the block pieces with carbon and release film in-between.

[mjalaly]

The pieces will match perfect with this method.

When the wing is cut from a block that one cut creates both the wing and the female parts from the one block with just a wire cut thickness difference. You get the wing, a top female and a bottom female. Then you are basically reassembling the block pieces with carbon and release film in-between.

Again look at the shape. Yes i am aware that the hot wire will make two half’s but then there is a second and third operation perpendicular to the first cut.

Yes if it was a simple wing that would work but look at the profile. There isnt a good way to cut the shape since you need to move the wire in two different planes. The shape also changes in both directions that the wire cannot compensate for.

If i can get access to a friends cnc router then yes i can do it this way… but that may not happen.

[mjalaly]

I have successfully bagged a couple of sets of glider wings that are curved. I used 60 psi foam that was cut with a hot wire for the cores. The wing halves were vacuum bagged similar to the method described here: http://www.pilotsguide.com/rc/vacbag.shtml

That website talks about using mylar that is 0.007" thick. The mylar that I use is 0.014" thick, but I was forming the wing on 9 foot radius. The mylar does resist being bent to that radius. Your wing looks like it has a tighter bend so a thinner mylar (or more flexible material) would probably be helpful.

I’ve attached a few pictures showing the finished product and the process.

I suspect that a similar process might work for your wing, but it would require some experimenting.

The mylar wont conform to my shape… i tried.

[fasta]

Again look at the shape. Yes i am aware that the hot wire will make two half’s but then there is a second and third operation perpendicular to the first cut.

Yes if it was a simple wing that would work but look at the profile. There isnt a good way to cut the shape since you need to move the wire in two different planes. The shape also changes in both directions that the wire cannot compensate for.

If i can get access to a friends cnc router then yes i can do it this way… but that may not happen.

Sorry I had not even looked at the pictures.

Your shaping method would work, but I have a similar method you could try.

Making a wood/mdf jig that you can use to laminate layers of foam to the correct thickness. So if your wing is 50mm thick you might use 4 layers of 12mm or 1/2" thick foam and vacumm bag this onto your jig so it forms the bent profile of the wing accurately. Then taking it a step further you could also add a couple of layers of carbon or glass at the centreline so that the laminated shape would also have a composite fin in the middle that might help as a reference for shaping both sides?