diggs_74

After seeing what it costs to get set up with CNC molds and all the expensive materials.... So in an effort to make a "cheap" composite wing I started doing some tests. I used a Bill V. wing core and shucks, 2 oz. cloth inside and outside, wax paper, 1/16" balsa and some cheap rattle can primer.... A vacuum pump would definitely be a help because a guy can only stack so many gallons of paint on his work bench for weight I didn't do anything to the balsa at this point because I didn't want to put that much time in it if it wasn't going to work.

This way is definitely more time consuming, it's kind of a pain to get everything lined up but even if it takes me 10 hours of labor it's only about $30 worth of material....

Any issues anybody sees please let me know... At this point it isn't a big investment, I would rather know now than find out at the field....

splatt

So.... what's that thing going to be ???

diggs_74

This was just a test panel.. I didn't want to waste perfectly good balsa to find out it wouldn't work so I just did a 6" section of the wing. The next step will be to do another one, put in the spar, and put them to together. After all that I will do a full wing and see how that goes. I haven't designed any of the hard points or anything yet...

DHG

My Feedback: (7)

Lee,

I think you're on the right track. FWIW, I lined my shucks with .014" Mylar. I have made glass-skinned shucks in the past and had release issues. There's nothing worse than molding up a beautiful, glossy, pre-painted wing and then having to dent it by inserting a plastic knife to pry it away from the shucks. With the Mylar, you just lift the whole thing out and peel off the Mylar panels.

If you were careful, you might accomplish the same thing using waxed paper or release film instead of Mylar. But I thought Mylar would be preferable because it's stiff, so it'll bridge over little imperfections like stray dust particles & whatnot.

Pre-painting may be a challenge. On my one and only attempt so far at pre-painting the Mylar panels, the paint came right up along with the masking material. This may have more to do with the type of paint or how thick it's applied, or perhaps the amount of wax I put on the Mylar, rather than any inherent problem with the Mylar itself. It's certainly worth another try.

Duane Gall
RCPRO

diggs_74

The wax paper at this point seems to work very well with just the primer... I don't think I will attemp to paint on it just prime to fill the weave. I have already seen what you're talking about with regards to the imperfections and the wax paper not bridging the gaps and bumps and such. I have thought about glassing the shuck just to make it a bit more rigid but I would still use the paper or mylar or whatever. I must say that it turned out 10 times better than I expected it to on my first try. Last night I read through daven's wing mold post just to make sure I wasn't missing anything.

StregaFlyer

Lee,

I have some Q500 wings here that my dad gave me since he doesn't race anymore.. These are normal foam cores, but they are covered with carbon fiber, like what would be used for spars..But they carbon fiber is the width of the wing.. Very nice wings, just curious to see how fast they will be... Also Lee, we have a small wing press i believe it is like 28 inches or so.. It works great on the wings.. I'll get a picture and send it to you so maybe you can construct one yourself... We had a 54" wing press, but my dad cut it in half, got no idea why.....

diggs_74

A wing press would be cool... I did notice in my test piece last night the the surface of the panel looks and feels like a golf ball... I'm not sure if this if from too much pressure or not enough...I'm thinking its not enough. Anyway, I'll get some mylar and use that instead of the waxpaper at least for the side the people will see anyway. I would think the mylar will be stiff enough so that the beads in the foam won't effect the surface of the skins. I will be ordering a vacuum pump and bags and such when I order the mylar.... I need one to do my tails anyway.

diggs_74

I'm in the final stages of getting everything together to do my first "composite" wing... Skins are done and all the lines are laid out for the ailerons and hard points but I've got one issue I need to take care of before I go any further.... Wing tips....

I have concidered a few different methods but all have the same issue, compound curves with balsa. We all know how well that works, especially without a rigid mold and strong vacuum pump. I think I'm going to end up sticking some foam out at the tips and then shape and glass that.... The next question is what shape. I've been looking at a lot of pics of the major composites but there really aren't any good shots of the wing tips. Any thoughts??.

DHG

My Feedback: (7)

Lee,

The Vortex and ShotGun are as good as any. Top view looks like the upper curve of the airfoil, but angled so that the nose of the airfoil is about 1.5 inches inboard of the tail of the airfoil, and the point of maximum span is at the rear corner of the tip.

Front view should be somewhere between a triangular cross-section (the old Scat Cat design) and a half-dowel. Theorists say that having a crisp edge at the centerline of the airfoil is better than a smooth, rounded edge -- something about not encouraging the high-pressure air on the bottom from rolling around the tip to mix with the low-pressure air on top. When it does that, you get more of a tip vortex, which wastes energy.

But, to quote a sailplane guy (I think it may have been Dave Thornburg): "Aerodynamically, the most important thing about wingtips is the distance between them."

Duane Gall
RCPRO

diggs_74

Thanks Duane, that helps a bit.... I think that's something I may be able to pull off in some fashion... The skins I made are about 53" so I would have enough material to do what ever I decided.... Should have something to show after christmas I hope.

diggs_74

After going thru all the motions on my "cheap" composite wing I have decided that A: I need a vacuum pump, #2 I need to be a bit more cafeful reading the tape measure, and Lastly: I should not have worked on it the second day of quiting smoking.....

Both the skins turned out very nice and the spar and core material laid out great.... However, when joining the top and bottom skins over the spar I neglected some details (see #2) and ended up with a nice looking wing that wasn't usable... I then proceeded to stomp it into a few pieces and throw it in the garbage (see Lastly

I have not however given up, I just need to get another core or 2 from my good buddy Bill V. If you're online Bill send me an email as I am currently floating around in southern Cal.

Bill Vargas

My Feedback: (5)

LOL,,, your floating around is an understatement for us here on the west coast!


BV

Bill Vargas

My Feedback: (5)

LOL,,, your floating around is an understatement for us here on the west coast at the moment!


BV

diggs_74

I'll still take rain and 60's instead of snow and 0's

Stikum

If you cut the original cores/shucks out of blue foam, you'd have a much smoother, stiffer mold.....


Edited fo tpyoz

diggs_74

That's a good thought.... What do you think Bill V., could you cut one of you wing cores out of the blue foam??

Mluvara

My Feedback: (10)

Try spyder foam. It has a grain structure that is vertical and helps prevent it from being crushed.

Michael

Bill Vargas

My Feedback: (5)

Hmmmmm, Rain,,, Rain SUCKS!

We've had alot of rain here the past few days. The pic here is the airport at which I work at and about half the runway is under water now. My hangar is now under water also with no relief in sight[:@]

BV

Terryoc

Some pics of my molds and wings I use a blue foam called roofmate grade and have done for many years.
This wing is for F3D but met up with another plane at the wrong spot. The molds have now done 12 wings as have the mylar lining the wing is painted in the mold so to speak the mylar is waxed then painted .
I have a wooden box I made inside the vac bag and the mold goes in on top of it to keep the mold straight ,max vacuum I use is 15hg about minus 8 psi and have had no problem with compression of the mold at this vacuum just make sure the bag does not pull tight accross corners by giving it lots of slack.
The pen lines on the mold are to locate the mylar and are the Leading and trailing edges ,the foam is protected by thin packing tape on the edges to stop the resin sticking to it.
The wing has molded tips but is not so hard because it is only about 10mm thick out there.
The best way I have found to cut the blue foam is very slow with a cold ish wire each cut on this wing takes about 3 minutes.
Hope this helps
Terry

diggs_74

That looks pretty nice Terry.... I think that will definately be worth a try.... I figure since I have all the materials I might as well not quit until they're all gone

[email protected]

Terry does some real nice work, currently running his F3d models in NZ......they are neat, tidy and his moulding is a work of art. You should ask him to do a brief article on his fuselage moulding. I'll leave that to him but it would be worth some time to comprehend what he does. Trevor H

diggs_74

Hey Bill, was that you I saw on the news taxing planes down the highway to get them out up to higher ground in Corona?? I just caught the last bit of the report from there.

Bill Vargas

My Feedback: (5)

Hi Lee, umm, its possible,,, we had newspeople all over the airport yesterday. The 3200' runway has been reduced to about 300' now and the water is still rising. In the pic here(taken yesterday morning) I'm standing just beyond midfield.


BV

diggs_74

What a mess.... You guys got your work cut out for you that's for sure.... I guess I'll take snow any day compared to all the rain...

SSAN

Hey Bill,

Don't get wash away in the flood now. We don't need another statistic and want you here at Speedworld for the Winterfest race.