Finally, wing mold closed up and all set for the evening. I'll be like a kid in a candy store when I get up tomorrow because I can't wait to see the results!

Once again, great job!!!

I am in the middle of making a plugs for my 35% Extra 300SX.
The plug for the fuse is 89" long and is a monster, while my wing plug is has a 44.5" span and is 23" at the root and 13.5" at the tip. The wing plug will be used to make both the right and left wing, so the plug has to be perfectly symetrical and is taking a long time to produce. I am making hollow core wings and am very excited about them.

The fuse and wings will be Nomex Honeycomb sandwiched with 1.4oz prepreg glass on a 45°.

Once the plugs are done, then I can experiment with using contest balsa and other materials as the core material to cut down the cost.

Keep up the good work!!!

Darrin C

First of all, great work! Can't wait to see the wings come out of the mold!

This is too ironic. I've just been doing research and getting advice on how to do wing molds, and then you post all this... Perfect!

More, more, more!
Thanks.

Mike,

I was wondering when you would find this.

He has some great pics!

Darrin C

I just pulled the wing out of the mold this morning ... Nice! A little heavy, but not bad for the first wing. I'll take some photos when I get home tonight. Gotta run off this morning...

Michael

Hi Darrin,

Yeah, this is cool. I'm finally going to do my first wing molds this spring, (for my "Pattern" design) and so this article is a great reference.

Okay.. final results are in... Wing came out pretty good. It's about 6 oz over what my foam wing weighed, but that is not surprising since some of the things are way overdone on this wing. Next will be at least 6 oz lighter! Live and learn

Here's some photos. I apologize for the lighting. It's hard to shoot this white surface in the garage with flourescent lights and I'll take some better ones in a few days. It was a long day today and I'm going to be a couch potato for the rest of the night...

Profile of the laminar flow airfoil

The benefit of composite wings - Skin hinging! Hinge is the upper surface of the wing.

Wing outline, from the top. The green is the mold release film (PVA). You can see where I started to peel it up. Normally, it has to be washed off with soap and water, but I guess I put it on thick enough.

Profile of the wing. Note that there are 4 servo hatch bays. There will be flaps and ailerons on this wing. Both the flaps and ailerons will be used to help the airplane turn in what is called "camber changing". About 5 degrees of downward deflection on both ail and flaps will be used when the elevator is pulled up, creating lift.

Mold release being lifted off.

Wing leading edge before trimming and one of the servo hatch bays. I cut it out to take a peek inside the wing.

Wing LE closeup.

This shows the thickness of the glass which is on the edge of the mold. It adds 1/32" to 1/16" thickness to the wing.

Bad photo, but it shows the wing profile. It's fresh out of the mold with the flashing untrimmed.

Well, that's it for the night...

Great Work! I look forward to seeing the next steps, assembly, flying, etc..

Thanks for all the great photos. I wish more people who do plugs and molds would post some information like this, so we could all improve what we do.

Michael,

Looks great. That laminar airfoil looks like the one you sent me about a year ago. It looks to be a variant of Naca 66. Very similar to the Vortex and Neme-Q Q500 planes.

I see you primed it in the mold, do you have plans of painting and clearcoating in the mold also?

Let me know if you would be interested in selling one of these planes? We don't race Giant Scale racing up here, but I've always liked that plane and would love to have a composite one.

Hi Daven,

The airfoil is probably the same or close to what I sent you. Did you build a wing with it? I sent it to several people and have heard nothing back.

I started with a Nasa-Langley nlf-213 and modified it to get what is there. I played around with another airfoil since I designed this one that is much better, but I was not about to re-mold the fuselage to make it fit!

I have had thoughts about producing it, but don't have the time. I have several people in the past that I have promised it to and told them that it would be awhile. I need to get those out of the way first. I'll probably have to outsource it if I do. This summer I may have some time to write a manual,etc. Right now my schedule changes week to week.

The model actually isn't giant scale. This is small in comparison. A giant scale racing Tsunami would have a 91" or so wingspan. This one is only like 55".

I have not yet painted a mold like you described. I still get imperfections and bubbles,etc - but I'll get better as time goes on. I like to take small steps. Plus, I am actually trying to stay away from a lot of the paints out there, so minimizing the stuff that I am near health wise is a plus. I' m young and would like to live long, so I try to be careful. This hobby actually exposes you to a lot of "nice stuff"...

Michael

I did not cut any cores with your airfoil. For National competition I have pretty much gone to purchased composite planes. I just don't have the time, or building skills to compete with the Chuck Bridges of the world. And with the new Lanier $110 Q500 arf available for local club races, I probably won't be doing a whole lot of Quickee building.

I agree with you about the nasty chemicals that many of us use. I have an issue with CA, and the PPG Deltron paint I use is terrible.

If you change your mind on kitting this bird, I would send you a deposit tommorrow.

Will you be at the JR Gold Cup Q40 Race in Phoenix this weekend? I'll be flying down tommorrow.

I didn't organize my emails from back when I was sending out the airfoil and never found out if anyone had good luck with them, so that's why I asked.

I'm just afraid with the stuff out there that I'll harm myself. I've used PPG once or twice and don't want to intentionally kill myself. I used to use hobbypoxy every so often before it went away, but was surprised to read the clear coat label in that it had a form of cyanide in it!

I'll let you know if I get ready to make one for you. I intentionally took off serious racing (the giant scale) this year so that I can finish my last year of college. I tend to get too distracted if I'm competing and I don't need to be in the garage laying up planes like crazy either!

I won't be at the JR cup. I'm not avidly into QM, but maybe one day! Wouldn't mind going to one. If it was earlier this year, I could have probably went because I had a free ticket to use up and have a friend in Phx.

Michael

Mluvara,

You might want to consider using Prepreg fiberglass and carbon fiber. This material already has the epoxy in the cloth and allows you to preform very consistent back to back layups. The cost is comparable if not cheaper in the long run than wet layups.

You cut your cloth to size, lay in the mold, vacuum bag it and put in the oven under vacuum and bake it at around 260°F for approximately one hour. You can make a oven out of insulation board found at you local Home Depot ect... and use halogen spot lamps for the heat source.

The downside is that you have to store the prepreg at freezing, but if you look in your local paper or trading post and you can find a deep freeze very inexspensively ($50 to $75).

As long as you vent the oven, I believe that prepreg is the least hazardous way to preform epoxy based layups and is the only way to go for long term use.

Just a idea,

Darrin C

One question,

What are you doing to the 1/16" balsa to keep it from absorbing to much resin? My experiance shows me that the balsa acts like a sponge.

I have heard of people using AquaNet hairspray in the purple bottle, they spray it on until it pools, then once dry, lightly sanding it, repeating this a couple of times.

I would love to hear so other ideas!

Darrin C

I think I can answer this for you since I'm Mike's brother and I was the extra set of hands while laying up the wing, which is MINE!

The peel-ply basically sucks up all the extra resin that is atop the balsa while being forced down in the vacuum. As you noticed there also is some paper towels used there, which are basically a breather, but when you pull the peel ply out, its generally got a LOT of epoxy on it..

I'm sure I can be wrong and my brother will elaborate.. I worked on the wing today and took some pics with the camera, and I'm sure he'll post them later tonite!


Chris

Darrin,

I really didn't address the problem of the balsa soaking up the resin. I realize that it is a sponge, but wanted to see how this came out the first time before I started experimenting. My first composite layup was with a stabilizer and it came out pretty good. We used balsa on that one and I have stuck with it. Eventually, I would like to use divinicel <sp?> foam and see what happens.

Seeing as how this wing came out super strong, I might try 1/32" balsa next time to give it less area to soak into. I'm a little leary as to to that thin though.

On the prepreg front, there's one problem. I did not postcure the mold, so I would have to take the mold up above the 260 you described with the plug back in it in order to bake the wings I would be bagging at a later time. It is an interesting idea and I may oneday try it.

Also not sure if I need a deep freez and exhaust hood in my garage! If I were a composite guru doing it every day, then maybe so.

Thanks for the insight. I'm learning every day!

Michael

One bit of advice on the Divinycell, you must fill the cells in the outer layer of the foam or you will be back to having a sponge that soak up your resin. Right before you lay up your piece, mix up a thick slurry of epoxy and microballons, spread this on to the Divinycell with a putty knife and fill the holes in the foam. Then proceed with your layup as normal. You will be amazed how much lighter this way comes out!!!

Darrin C

What about Rohacell? Do you have to do the same thing?