Don,

I would not use microballoons. Microballoons actually weaken epoxy, as we learned the hard way back in the '70s. Cabosil, cotton flox, or milled glass would be a much better choice. I usually mix enough in to make it the consistency of tooth paste, unless I need it to flow some. In that case I make it thinner. Microballoons are good for fillets or filling wood grain or weave in fiberglass. Your choice, your model, but them's the facts...

I was in New Orleans the week after Katrina, getting the railroad running again... and I have nothing good to say about it, so I'll say nothing at all......

Jack

Thanks Jack. What about just using straight epoxy?

Nevermind, I have located some milled glass .

Don

Straight epoxy is OK but can be brittle... Still better than microballoons...

See ya...

Jack

Nah, Jack and i will have to disagree a little on this one, a mix of microballons that makes your epoxy not as thick as toothpaste but gives it a somewhat whitish colur will be very strong and just fine. If nothing else my O3 wing build has been proof of that, and say at least a dozen or more other planes I've had during my life not to mention the rebuild work I have had to do on different glass boats.

The trick is not to mix to much into the epoxy, and mix it all VERY well for at least 5 minutes. But, to each his own.

Steve's correct if you don't put too much in, it's OK. If you really load it up, it is weakened. I believe Dr. Drela commented on this some time ago...

I just potted my 17/32 tubes into my wing roots for my Hawk build. I used a bit of milled glass and some Cabosil, but it has to flow some so I heated it as it went in... It went off a little faster than what it's supposed to... which just meant I didn't have to wait as long to do the other side... not a bad thing. I am going out to bend my joiner.

Left to do are: Fit wings and joiner to fuselage; Fit stab; Fit rudder; Make servo tray; Fit and rig spoilers; Cover; Install push rods; Balance; Fly... All the parts are made... If I was going to be home this week, I'd finish her... Alas, duty calls...

Jack

You forgot to list one thing Jack...



Take Pictures of it!

Jeff

Talcum powder is another very good additive to epoxy, we used to use this back in my Skiff sailing days for filling "combat" holes and scrapes.
Very light and strong, but yes to the previous post, only use enough to slightly thicken.
Dale

Question on the OlyIII , i have a Marks Models Windfree (orininal kit) in the box but really like the looks of the OlyIII would it be pheasable to make the wings striaght with out the poly and then add the flaps and ailerons ,
i had an olyII when i was in high school and a windfree always did like the straight style wings

Thanks

John

Way back in the seventies and early eighties, I participated in F3B Team Trials and made it thru to the finals three times. Imagine doing this with woody sailplanes back then, before carbon, we were all learning with each wing failure as we turned Base B in the Speed runs, what worked and what didn't work.

Lesson # 20040092 : brass tubes surrounded by any 30 minute and up cure time epoxy, mixed or not mixed ( reasonably ) with Mirco Balloons, placed between the spars with 1/16 plywood horizontal shear webs on both sides of the brass tube and attached to the sides of the spars do not break when the wing rod is inside the brass tubes and the plane is negotiating the speed turn a Base B. ( RCC Group's longest run on sentence ).

Because,the weakest bending ( break ) point is located at the ends of the brass tubes.

So once we figured that out, it became all about the size and strength of the wing rod. And then we discovered the use of carbon.

Ray
Sky Bench
http://www.skybench.com

Hi Ray, sorry to get off topic, but heck, this whole thread is a wandering goat! and thats a good thing.
I am looking at building my 2m Bird with joiner rods that are rectangular hardened plate steel that fits into 11mmx2.2 mm rectangular brass tubing that is available in Aus from a local RC retailer. I am considering the length of both the rect tube and solid joiner that might be best suited to the standard 2M Bird wing build. I might add the 0.014" Dave Brown carbon caps to the 2M bird spars after witnessing how they helped my OlyIII wings hold together after a fast verical impact and some genuinely strenuous launches, and I mean heavy launch pressure from F3B winch and histart, histart always won the altitude with its light line so far.
How does 3" of rectangular rod and tube per wing sound for the capped 2M bird?

Here's a few pix of what I've done to ready the tube box on my first panel. Please let me know if you see something . The tube is tacked in place and is leveled and square...should be good to go .

Looking good Don! I like the carbon pad idea. Should make for a strong connection AND spread the load out a little better on rough landings.

Jeff

Olyers,

I noticed on the plans that the rear W-11 ply spar brace shows to be shorter than the front. Is this for ease of making the spoiler control horn clearance? I saw no reference to this anywhere although I am deaf, dumb and blind (tooted) after about 6:00pm .

Don

Originally Posted by atmosteve

Hi Ray, sorry to get off topic, but heck, this whole thread is a wandering goat! and thats a good thing.
I am looking at building my 2m Bird with joiner rods that are rectangular hardened plate steel that fits into 11mmx2.2 mm rectangular brass tubing that is available in Aus from a local RC retailer. I am considering the length of both the rect tube and solid joiner that might be best suited to the standard 2M Bird wing build. I might add the 0.014" Dave Brown carbon caps to the 2M bird spars after witnessing how they helped my OlyIII wings hold together after a fast verical impact and some genuinely strenuous launches, and I mean heavy launch pressure from F3B winch and histart, histart always won the altitude with its light line so far.
How does 3" of rectangular rod and tube per wing sound for the capped 2M bird?

are you saying a 6 inch wing joiner ???

Ray
Sky Bench
http://www.skybench.com

Ray, thats right. Do you think 6" is a little to excessive and weighty?