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Old Nov 29, 2008, 11:09 PM
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Glassing the P-40 Wing

Well, with the cold weather back in town, I've been spending some time with my P40 again. With the fuselage mould complete, I now have to finish a wing so that I can get on with the moulding.
After months of sanding filler and primer in my spare time, I've come to the point in the road where I'm satisfied that the form of the wing is good enough to lay down some glass cloth. This is always the hardest part for me - moving on. I always want things as close to perfection as I can get them before I lock it in with glass, but at some point you have to just stop and lay the dang cloth down! (Tip symmetry drives me nuts!)

If you're new to this operation, here are some things to note. Most of all, don't be discouraged from trying it! Personally, I think it's a lot easier than film - and there's more sanding fun to be had! lol

- I mixed equal parts of resin, hardener, and methyl hydrate (denatured alcohol in USA) in order to get a nice thin watery consistency. Don't fill the weave, just wet the cloth out and let it dry.

- Don't trim too closely (the weave will move around as you brush and what looks like it may fit, may not by the time that you get there. If you run a sanding block aroung the edge once it's dry, the excess cloth will pretty much fall off leaving a nice edge.

- Start in the middle and work outwards.

- Don't try to do too much area at one time, and don't worry about overlapping sections. You won't be able to see these seams after a finish coat of epoxy later.
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Old Dec 02, 2008, 04:08 AM
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Wing is glassed.
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Old Dec 03, 2008, 05:36 PM
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Scuffed everything up after the cloth was on with some 100 grit and hit it with another thinned coat of epoxy before retiring last night. Found some time this afternoon to get at it with some 150 grit on the longboard and hit it again with some el cheapo primer. Still plenty of work to do, but it's further along than it was...
Of course I had to do the requisite mock up to make sure that the wing still fit the saddle. I'm not happy with fit up front where the bellypan, wing fillet, and leading edge meet up. The fit is still good and tight, but there's room for asthetic improvement. I'll do some more finishing on the underside before getting to those things though.
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Old Dec 05, 2008, 06:14 PM
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...just taking some photos for my own future reference - thought I'd post a couple for those of us who enjoy watching bodywork - personally, I find pictures much more entertaining than the real thing

I actually laid down another super thin coat of epoxy on the top surface of the wing since the last post trying to fill a few minor fisheye type situations, but it didn't really change very much, so I sanded it off, primed it again and was forced to get out the glazing putty this afternoon. Things are moving in right direction again. What am I doing? sanding, sanding, sanding, sanding, sanding.........
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Old Dec 05, 2008, 06:59 PM
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WOW!! I have some learning to do. WOW!!!
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Old Dec 07, 2008, 06:35 PM
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I promise not to make you sit through every step of the finishing process, but people keep asking me how much sanding is really required. I can't give a straight answer, but I should be able to bore you enough to get the idea across! lol Today, I hit the topside again with some glazing putty, and then sanded it with 220 followed by some 600. It's starting to take shape. The underside needs a guide coat of primer before I can tell where I'm at after a couple of thinned coats of epoxy. Actually, I put some microballoons in the last coat on the underside to help with the sanding last time so it shouldn't be too far off. Unfortunately it's below zero out in the shed, so I will have to set up a little spray booth inside the backroom in the basement and ventilate out the window. Stay tuned....
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Old Dec 11, 2008, 02:17 PM
Trampling out the vintage
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Really impressive work. Question for you: How much does your molded fuse weigh, and how does that compare to say a built-up balsa fuse? I'm wondering if this would work for smaller (say 40" wing span") models.

I admire your patience and persistence and willingness to share your knowledge - keep it up!
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Old Dec 11, 2008, 02:52 PM
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Hi Greg, the fibreglass fuse without a firewall or servo tray is about 1/2 the weight of the built up one. I posted a bunch of details already that you can find at the end of page two of this thread.
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Old Dec 11, 2008, 06:27 PM
Trampling out the vintage
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Thanks for directing me to that post, I see what you mean. If you wanted to trade cost for weight reduction, would it be possible to reduce the weight further via say carbon fiber or kevlar, vs. all-fiberglass?

BTW at some point you might want to put something in the "electric warbird" and "scale electric" forums referencing your work. Those modelers like lots of detail while keeping it light. However they seem to work entirely in balsa and foam. For those willing to invest the extra work in a mold, the rewards seem like they would be impressive.
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Old Dec 11, 2008, 06:55 PM
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Truth be told, I just haven't reached that point yet. In the future I will be running some trials that I hope will prove useful for us. I have always been concerned about rf interference from carbon fibre, but lately I have seen a couple of projects and had some interesting conversations that have me rethinking my hesitation in regards to a little feasibility investigation. Another approach that I will be looking into is building an integral framework into the layup to form a load carrying composite structure while decreasing the thickness of what lies in between. This would be a blend of some of the more traditional structures with the material properties of composites. I see some of the glider types moving into this area in their hollow moulded wing structures. Ultimately I hope that this will allow me tune wing loading and strength to a point that I can produce something targeted for intended use or available power. All I can say at this point is that fortune favours the brave, and stay tuned.
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Old Dec 11, 2008, 06:59 PM
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...and of course Rome wasn't built in a day... lol
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Old Dec 12, 2008, 09:55 AM
Trampling out the vintage
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Well it's good to hear that you think there is potential. What I would like to see, as a modeler, is more borrowing of techniques from the composite glider crew by the scale modeling crowd. Your thread and videos are the best job I've seen of doing that. Built-up balsa models with sheeted surfaces can look fabulous when surfaced with fiberglass and detailed, but it takes forever and is prohibitively heavy on models in the 36"-55" span range which are the 'sweet spot' for electric power systems. Foam is lighter than anything but looks inferior to a well-done balsa/fiberglass model and is difficult to repair to a high cosmetic standard. Repair is a fact of life if you fly your models.

Your approach potentially offers the best of both worlds - great detail and light weight. As well as ability to mold replacement parts or whole models due to crash.
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Old Dec 19, 2008, 02:14 AM
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I found a couple of minutes to do some more sanding on the P-40 wing plug this evening. As you can see, there is still much work to be done, but none the less things are shaping up. With the holidays coming up, I hope that I will get a little closer to putting some panel lines etc, in place, but first things first, I must have a flat surface worthy of moving forward.
One of the things that gives me a kick is giving back to a hobby that kept me out of trouble as a kid, gave me distraction from the pressures of studying through my college years, and gave me something to call my own as I let the multinational corporate organizations rape and pillage me for all that my two engineering degrees and experience could yield them. (the trick is most definitely to bend them over first) Throughout this project I've hoped to inspire others. If you are out there and still need some motivation here's something to think about.
It began only weeks after posting the first video to youtube. First it was boat manufacturers, then it was artists. A couple of weeks later it was tool companies in the States, then it was Chinese ARF manufacturers. Today, it was a manufacturer of glass fuses for some of the names that I've only ever read about in Top Gun reports. If you are a young person out there who is looking to start a business, I would have to say that I have never seen market potential like I've seen here. You will not have to search for customers - they WILL contact you - no matter how anonymous you think you are....
Don't let others dissuade you, think it through for yourself. I only wish I had time to help them all.
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Old Dec 20, 2008, 08:54 AM
Trampling out the vintage
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You are working to a very high standard, that wing looks very smooth. While I understand that you are going to use the wing as a plug, could you acually fly this wing on a model?
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Old Dec 20, 2008, 09:14 AM
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Sure thing Greg - Same deal.

Actually, if you want to get technical, I've blocked off the gear mounts, tucked the aileron linkage into the wing, and blocked in the flap servo bays in order to facilitate moulding. But other than that - same thing. If I really wanted to, I could still fly this wing.

Finishing light and bright is really all about building straight to begin with, not about adding alot of filler and primer. Nice smooth rib profiles, and careful attention when sheeting go a long way. That's just my two cents worth for ya there.
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