I'm here for ya buddy whatever you need, just keep pluggin away...I know about that "Fiscal responsibility thang!! Reachin it also with my project...
I just have one question...
What are we all going to do with our morning coffee when you finish this blog? I mean ,for a lot of us it is how we start our day!!!


Jim

Here is a rendering of how I might make a skin. I was messing with some .75 ounce cloth and some 1/8" carbon fiber tow. The idea that I am going to test is this. If I run the CF tow nose to tail and set it every inch, and sandwich it between 2 layers of .75 ounce cloth how much with it weigh. The tow will work like little stringers. If I put down mold release on plexiglass, the a very thin layer of resin, next a layer of .75 FG, and then the tow, and another thin layer of resign, then .75 ounce FG, then to complete it the last layer of resin. squeegee off all the resin I can, then vacuum bag it.

The little section I played with was very strong and very light, and with my stringers and spars in my wing, wing support looks great. The only problem I see is that I will only be able to make 2 36"X48" sections a day. It will take about 2 weeks to make all the skins.

Just more R&D.

DAG

Originally Posted by coptercptn

I'm here for ya buddy whatever you need, just keep pluggin away...I know about that "Fiscal responsibility thang!! Reachin it also with my project...
I just have one question...
What are we all going to do with our morning coffee when you finish this blog? I mean ,for a lot of us it is how we start our day!!!


Jim

Well,
About a month after I get done posting my B-36 flights at SEFF 2010 I will start posting pics of my 300" C-130 design . Construction to start fall of 2010.

Thanks, DAG

Thanks Ojimy for the info, I thought I was on the right track.

Thanks, Cherokee Flyer, I just need to make sure I don't cut corners now, and I have to do this bird right.

Thanks guys, DAG

DAG: I think your doing an awesome job on the B36 and I have followed it from the beginning -each day. I was a C119 FE/FM in our unit on the C119C,C119G and C119L. The C's had 4360's just like the B36 and was a torque brute. I retired in 1998 as a Phase Dock -Supervisor on our units C130H's. The C130 300" sounds like an exciting build also. Carl Bachhuber flew his B36B this past Sunday for the first time and is doing more flight testing. Here is the link if you haven't seen pictures of his first flight. http://www.carlb-rcplanes.com/B-36page1.html

Be encouraged and keep up the outstanding work. Walt

Originally Posted by dag214

Here is a rendering of how I might make a skin. I was messing with some .75 ounce cloth and some 1/8" carbon fiber tow. The idea that I am going to test is this. If I run the CF tow nose to tail and set it every inch, and sandwich it between 2 layers of .75 ounce cloth how much with it weigh. The tow will work like little stringers. If I put down mold release on plexiglass, the a very thin layer of resin, next a layer of .75 FG, and then the tow, and another thin layer of resign, then .75 ounce FG, then to complete it the last layer of resin. squeegee off all the resin I can, then vacuum bag it.

The little section I played with was very strong and very light, and with my stringers and spars in my wing, wing support looks great. The only problem I see is that I will only be able to make 2 36"X48" sections a day. It will take about 2 weeks to make all the skins.

Just more R&D.

DAG

To simplify your process you probably should reverse the order of putting down the resin and the first layer of fiberglass since it will soak through. Also the second and third application of resin may not be necessary since the first layer will soak through. You will see how much to apply when you test it.

I dont think the tow will get you anything in compression but it should help in tension. Actually I would be worried about the whole thing in compression. Is the plan to apply this skin over balsa stringers?

How are you bagging it?

Originally Posted by bwalt822

To simplify your process you probably should reverse the order of putting down the resin and the first layer of fiberglass since it will soak through. Also the second and third application of resin may not be necessary since the first layer will soak through. You will see how much to apply when you test it.

I dont think the tow will get you anything in compression but it should help in tension. Actually I would be worried about the whole thing in compression. Is the plan to apply this skin over balsa stringers?

How are you bagging it?

I have made many skins out of FG and have never had it work by putting down the glass first, the idea is to put the resin on the plexiglass like it is a flat surface mold. I let the resin set up just enough to make sure I can't push the cloth through, then put down the cloth, a coat of resin, then the CF tow, next the top layer of FG then let all 3 layers flow together when I squeegee out all the resin I can, then take a section of heavy plastic with a garment bag valve and suck it all out. When done I have a FG panel that kind of lays as if it has wood grain in it. With the tow impregnated into the 2 layer of FG cloth it will give me just enough strength to support the FG skin spanning the 2" between my wing stringers. The reason for this R&D is to save every ounce of weight will trying to make a skin with out any balsa sheeting in the wing.

Thanks, Damon

Originally Posted by charlie11niner

DAG: I think your doing an awesome job on the B36 and I have followed it from the beginning -each day. I was a C119 FE/FM in our unit on the C119C,C119G and C119L. The C's had 4360's just like the B36 and was a torque brute. I retired in 1998 as a Phase Dock -Supervisor on our units C130H's. The C130 300" sounds like an exciting build also. Carl Bachhuber flew his B36B this past Sunday for the first time and is doing more flight testing. Here is the link if you haven't seen pictures of his first flight. http://www.carlb-rcplanes.com/B-36page1.html

Be encouraged and keep up the outstanding work. Walt

I still have no idea how he kept that under 100 pounds. It is fantastic what he built, and the plane looks 110% perfect.

I e-mailed Carl about a month ago asking when he was going to test fly it, but he never responded to my e-mail.

Thanks, DAG

Originally Posted by dag214

I have made many skins out of FG and have never had it work by putting down the glass first, the idea is to put the resin on the plexiglass like it is a flat surface mold. I let the resin set up just enough to make sure I can't push the cloth through, then put down the cloth, a coat of resin, then the CF tow, next the top layer of FG then let all 3 layers flow together when I squeegee out all the resin I can, then take a section of heavy plastic with a garment bag valve and suck it all out. When done I have a FG panel that kind of lays as if it has wood grain in it. With the tow impregnated into the 2 layer of FG cloth it will give me just enough strength to support the FG skin spanning the 2" between my wing stringers. The reason for this R&D is to save every ounce of weight will trying to make a skin with out any balsa sheeting in the wing.

Thanks, Damon

Sorry if I missed it but what kind of resin are you using and what do you mean "never had it work"? Did it not soak through to the other side or did it leave little pockets where the resin didnt completely fill in the cloth? The only cloth that I have had problems with the resin not soaking through have been very tightly woven and thick kevlar cloth. What do you use for a breather and release film?

Originally Posted by bwalt822

Sorry if I missed it but what kind of resin are you using and what do you mean "never had it work"? Did it not soak through to the other side or did it leave little pockets where the resin didnt completely fill in the cloth? The only cloth that I have had problems with the resin not soaking through have been very tightly woven and thick kevlar cloth. What do you use for a breather and release film?

In the past I used PolyEpoxy resin. at the beginning when I used just the cloth it was always to close to the surface, any light sanding (even to just get it ready for paint) made me get into the cloth. And I always had pin holes. I got my idea from watching a guy do a boat hull. He put in a gel coat, let it start to set up then put down the cloth. Looked like glass when it came out.

The way I would get it up was to slightly bend the plexiglass to pop it loss then lift it up. But just the other day I had a true aviation expert tell me all I need to do is hit the edge with my air compressor and it will pop right up.

It may end up to heavy, but I am going to test both PolyEpoxy and the WEST System.

But I have to tell you, my calcs must be screwed up somewhere for Carl's B-36 to weigh under 100 pounds with 6 gas engines and fuel is something. I know my plane is about 3 feet bigger, but he must be a master builder at building it light.

Thanks, DAG

Originally Posted by dag214

Well,
About a month after I get done posting my B-36 flights at SEFF 2010 I will start posting pics of my 300" C-130 design . Construction to start fall of 2010.

Thanks, DAG

C-130? What about the B-47? Better yet, the YB-60, I don't think it's ever been modeled, and you already have 60% of the design done!

I highly recommend the West Systems stuff but you will come to your own conclusion. Easy to get the right mixing proportions, doesnt smell, and it flows well.

When you got the pin holes do you mean holes completely through the fiberglass in between the strands and were you only using a single ply of fabric?

I dont know if you plan to use peel ply or perforated release film with breather but using those will cut down on the resin weight by a lot, maybe up to 20% depending on how wet your layups normally are. Peel ply will also give an excellent rough bonding surface for the inner side of the skin.

You mentioned a garment bag valve. How does that work?

DAG: I don't mean to jump off subject and forgive me. I was involved with the C130's for over 23 years in my career and I believe it will be an awesome build. I went to the Air force Museum in May 2006 and saw the very last C141 fly at her retirement there- the "Hanoi Taxi" 66-0177. What a beautiful majestic aircraft the C141 stretched B and C's were. I think it would make a beautiful RC model. It had the same fuselage cross section as the C130 but, with sweep wings and 4 jet engines and a T-Tail. So many wonderful aircraft out there to chose from and not enough time or $$$$.

I know whatever you build will be done in excellence.

Originally Posted by dag214

But I have to tell you, my calcs must be screwed up somewhere for Carl's B-36 to weigh under 100 pounds with 6 gas engines and fuel is something. I know my plane is about 3 feet bigger, but he must be a master builder at building it light.

Thanks, DAG

you should call him or email him... I'd bet he'd share info.

Dag I must say I've never heard of what you are proposing for a wing skin. Then after thinking about it it does make a lot of sense and I agree with you that it will serve the purpose.The sequence is correct as for putting a thin layer of resin down first and letting it cook. Some time ago I was molding some sail boat hulls and in order to mold it you put in the outer skin in first(gel coat). One time I put in pieces of mahogany in the mold with double sided tape and then some resin then the glass, boy the end result was stunning. Good luck and keep it going. navee8or.