Spychalla Aircraft

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After the waxing it is time to spray on the tooling gelcoat. I use a polyester based orange tooling gel. It is mixed with 2% MEKP Catalyst and sprayed on with a pressure pot. I have a 1 qt. pressure pot attachment for my BINKS Model 7 spray gun. The whole set-up can run $300 or more if you don't have one, yet you can't spray the gelcoat without it. The gelcoat goes on thick and then cures for about 1.5 hours. Then mix the same gelcoat with cabosil filler to make a paste that is used to fillet the sharp areas of the part where it would be tough to roll the glass into. You can apply the paste liberally over the hardened gelcoat. This is followed by 2 - 3 layers of 2 oz./sq.ft. chop strand mat rolled in place with general purpose polyester resin. The key to laminating a mold is to wet the glass with resin before you put it on the mold. We roll the resin into 8" X 8" pieces of the chop strand on a table, and then transfer it to the mold and roll the air out of it. From the pictures you can see that it is a messy process. When done we leave it cure overnight.

Leo

Spychalla Aircraft

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First Mold half is done. Cured up perfectly. I used a diamond cut-off wheel to trim the excess glass from the perimeter. The waxing worked well and my divider boards popped off very easily. You can see from the picture that it leaves a gelcoated fiberglass flange around the entire perimeter. Location pockets are now part of the mold. Today we waxed the rest of the plug and laminated the second half of the mold. The process is exactly the same as for the first half. Tomorrow we will pop the plug out of the mold. It will be a very exciting day. I will post pictures.

Leo

Heavy Date

Gonna be a busy winter for me I can tell already.

Thanks for showing us the steps to make a glass fuse. Very interesting!
Timing could not be better, I'll just be finishing my B-17 and will have a clean table waiting for the next project.
Hans

t_burley

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Hans, what about that PCM

Leo, Zach, nice work![8D]

Spychalla Aircraft

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Ahhh! This is a stage that I love. Popping the mold off the plug. It is the moment of truth regarding all the work we've pumped in. It all worked out and the mold halves released just fine. It will still be nearly 3 weeks until we laminate the first fuselage. Relief areas need to be added for the bottom hatch and the tailcone. Plus we have a 10 day family vacation that is going to interrupt things. However, we are pleased with the progress and on schedule for what we are seeking to accomplish. It is a good day.

Leo

F4u5

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saramos

[:@][>:][&:]

Spychalla Aircraft

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Zach used the same mold making process this week to make a separate mold for the belly pan access hatch and the tail cone. We won't be posting any progress now until after Aug. 11th due to a family vacation. At that time we should be getting into the lamination of parts off these molds.

Leo

Veltro

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u2fast:

I ran into a company at the AMA show in Ontario, CA, named FlyingFoam.com that will cut cores from your dimensions or plan. I believe the quote is free. They were doing demos and their CNC foam cutting machine was very impressive. Their pricing was quite reasonable, too. You may want to check them out. I'm probably going to build my wing from wood since I have the Bob Holman laser kit but my friend prefers foam and is seriously considering using this company.

- Jay

u2fast

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thx for the info, i havent decided, built up is fine with me too. barry

Canuck1

Great thread!! I have been wanting to do exactly what you are demonstrating. I do have a couple questions regarding the process.

1. Is a gell coat required after the application of the waxing? I was wondering if you could use very light cloth (.75oz) to do the initial first coat of glass matt, then adding to it to build up the thickness desired? I am asking this due to not having all the fancy equipment, and the knowledge of gell coat.

2. I am not to sure of the exact requirement of those small round rubber pieces you placed on the parting board, I assume it is for alignment later?

3. After the first side was glassed to the desired thickness, did you remove the centre cardboard pieces? Did you use the existing lip due to the glassing as the centre line for the other side?

4. Last question, Would it be an option to cut the fuse in 1/2, (down the centre line) mount it to a hard board, then glass both sides independantly? I have heard some fellow modellers discuss this method and I was wondering what your opinion on this is?

These questions may seem dumb, however I am curiuos to the exact steps. You guys are doing a great job and I am following this thread, as it gives me some inspiration.

Craig

Spychalla Aircraft

My Feedback: (34)

Craig,

Here are the answers to you questions below, numbers correspond to your numbered questions:

I am glad other modelers may benefit. That is what it is all about. Maybe it will help somebody and boost the hobby.

1. Gel coat is not absolutely required. You can make molds directly by glassing the surface. I can see 3 drawbacks of your method. You may get some print through from the glass in your mold on to your parts, the mold is not as repairable, and it will be harder to see air bubbles while you are laminating against the mold surface. Gel coat helps you avoid all these things.

2. The small round rubber pieces are just drafted pegs. They align the mold halves together. You could achieve the same principle a dozen different ways. This method is just quick and easy.

3. Yes, the center board was removed. Thrown away. The new lip of the first mold half is your new center board for the other side. A perfect matched fit.

4. You could cut or build a part in 2 halves. It is possible, but maybe more difficult. Here is why. As soon as you cut or build a curved shape like a fuse in halves, it is going to warp. Guaranteed. An eigth inch will kill you on a project like this. Think about it. You need a glove fit of the mold halves to pull this off. If you can get a perfect matched fit then go for it. If not, then consider my methods.

Leo

NickC5FE

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Let me just say......AWESOME WORK. Looks great. Nick

FalconWings10

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Looks like Century Jet and Robart are going to be selling ALOT of those new landing gear systems! I've got my fuse on hold to see how this turns out. Leo, you are the man!

Spychalla Aircraft

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We are back from vacation and back at the process of finishing off this Wildcat mold project. The tailcone mold was the latest completion. The small mold is complete and a step was added to the back section of the main mold to provide an overlapping bond joint. By the end of this weekend we should have laminated and pulled the first sample fuselage. The first one is going to me used for evaluation of the mold and for making templates for the internal formers.

Leo

FalconWings10

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Leo, can you tell yet how light the aft moment will be?

Spychalla Aircraft

My Feedback: (34)

Well we all know the deal on a Wildcat... Make the tail as light as possible. Less weight will mean less lead in the nose. Doug Imes has a G-62 and 2.2 lbs. in the nose to balance his built-up wooden fuse. The goal here is to be lighter than built-up. Ultimately we won't know until somebody finishes an airframe. My goal is to evaluate the laminate thickness on the tail and judge it for rigidity and strength. This is all that can be achieve during this stage.

Leo

Canuck1

Cant wait to see the progress with the fuselage. Great work!!

Craig

RickVB

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Could this explain the "banana" shaped fuses you see from outfits like IMP sometimes?

Spychalla Aircraft

My Feedback: (34)

We laminated and pulled the first fuse from the mold. It is really cool. I will take pictures and show you how we do it on fuse #2 or 3. This one is just practice. I like the laminate schedule and thickness. Overall it feels light. The tail is only 2 layers of 6 oz. so it is thin and flexible, but I think we have to keep it that way so it does not get tail heavy. One or two formers may be required in the aft section to stiffen it up. I created an F4 Bulkhead pattern for mounting the gear. It also allowed me to figure out how we are going to transfer the load from the spar to the fuse. You can see from the pictures what I've got planned. It is built outside the fuse and then glassed in with the spar in place so it locates accurately. Pulling the first fuse damaged the mold in some small areas. We had a few undercuts that hung-up on us. Zach is going to repair them tomorrow.

Leo

carlbecker

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Leo,
Looking very nice. Just a suggestion about the landing gear mounting beam. I have had a rough landing with mine and the aluminum plate I used took most of the abuse. I did not make it removable which made the repair harder. Currently I use ply sockets and just bolt the mounting beam with 4 through bolts. Its strong enough and fails before the gear. The Robart gear is strong but I don't want to stress it more than I have to. I guess if all my landings where perfect then it would not be an issue.

Looks like a good tube mount. I think the fuel tank will fit good behind the wing tube.

Can not wait! Keep up the great work and photos!!

Carl

rrudytoo

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Hi Leo,

Like the rest of the scale rc community, I've been watching your progress with more than a little interest. You have much to be proud of, my friend! It has been a real educaton watching this mold, and now final product, come to life. Absolutely fascinating!

When do you expect to have the 'glass fuselages ready for sale? How long is the waiting list now? And...........how much will you charge for one of the Wildcat fuselages? Inquiring minds want to know.

Thank you for your hard work and knowledge. It has been a real experience keeping up with your post.

Al

Spychalla Aircraft

My Feedback: (34)

Al,

As I have mentioned before, I am walking a fine line here. I am not a paid advertiser, so I have to be careful that this thread does not turn into an advertisement. The moment that it does I know that It will get shutdown. Yet in the meantime I think folks are enjoying it and learning in the process so the thread continues. I'll answer all your questions via a private message, however I believe we will have the technical issues on this fuse figured out this week and be able to make the first decent usable Wildcat Fuse before the end of August. Zach and I need to crank out a dozen of these babies at the moment. It is going to get tough because he heads back to school in 2 weeks. I'll be picking up the ball and burning the midnight oil for some time.

Leo

Spychalla Aircraft

My Feedback: (34)

Stepping back through the laminate process. 1) We wax the mold 5 times for the initial pull. Only once each time after that. 2) We start by applying local 6 oz. reinforcements around the stab. The polyester resin is cured with MEKP at 1%. 3) A filler paste is mixed from polyester resin and White Flocking. White Flocking is a filler material that is bleached sawdust. It looks like flour. Amazingly it is used heavily in the food industry as a filler for cake mix, pudding etc. I bought a 50# bag from a local fiberglass shop for $75. It will last me a lifetime. You mix it to the consistency of axle grease and then smooth it into all the tight fillets and radii. This step reduces air bubbles and fills the areas where you cannot bend the glass. 4) We apply two layers of 6 oz. glass to the whole fuse and then two additional layers of 6 oz. to the front area. Everything from the back of the wing forward. 5) You let it cure for about 1 hr. to a leather like consistency, then you "Green Trim". The green trim is an important step. You can cut the excess off the halves easily with a sharp blade when the resin is just thick enough. Too thick and it is extremely difficult. Too soft and you pull up glass. You'll know from experience when it is just right. A mold half can be trimmed in about 2 min. if you catch it at the right time. 6) You clamp and join the mold halves. I will show that in the next post.

Spychalla Aircraft

My Feedback: (34)

Here are shots of the laminating and after green trim. I learned from a laminating expert that you try not to fight the glass. Work with it. If it bunches up while you wetting it out, just let it. Once it is wetted with resin you can more easily work out the wrinkles and air bubbles out. At a 1% MEKP cure level we have all 4 layers wet before it starts to kick. Patience! Patience! Then you have to know when to get off it. I learned this from a boat builder in Pipestone MN. There comes a point when you focus so hard on fixing one small air bubble or something that you screw up the rest of the part. Quit while your ahead and get off of it!

Leo