speedracerntrixie

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LOL Ken. If I was to do that I would end up with a 14 lb turd. With a little luck I can hit it with the first application of primer. I have all the materials for the mold and first couple of fuselages on the way. The first fuselage will most likely end up being unusable. The plan is to lay up the first one lighter then what I think will work. From there I can determine exactly where the structure needs more strength and where it does not. I think that is a better approach then making a heavy one and trying to figure out where to remove weight. Just think about how much better it would fly at 10 lbs as opposed to 11 lbs.

Pylonracr

Cool it is almost done. Now all it needs is a coat of paint. That shouldn't take more than 6 months or so...................

Scott

kenh3497

OR..... 90% done and 90% left to go!

Ken

born2build

I once framed up a kit in one weekend (G.P. Sportster 60). I call it "binge-building."
So, how come it took me a month to finish it?
By the way, I thought all modern pattern ships were biplanes...what with those funny little wings stuck to the canopy.
Don't bother, I'll find my own way out! Tens across the board!

speedracerntrixie

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LOL the Nevada boys sure are fired up. I have to admit that I used to be much faster with my builds. These days I work on stuff when I feel like doing so. They come out much nicer.

born2build

I never build because I feel I should. I only build when I feel like building. The Sportster was the exception, not the rule.
Besides, it's a fairly simple build. Not to mention I had built one before.
The aircraft pictured is a Great Planes T-Craft converted to electric. With a 56" wingspan, she comes in at 3lbs, 4 oz. Yeah, that'll do.

Pylonracr

Who you callin' a boy there son?????????

born2build

Um, I think he's calling us boys, "Junior." Ha! Truth to tell, I'd rather be called one of the boys than an old geezer. At this stage, I'll take what I can get!
So, how's it goin' upstate? Got your winter projects lined up?

speedracerntrixie

My Feedback: (29)

Well Scott, we do play with toy airplanes right? LOL.

Not much happening right now except for wrapping the fuselage plug in a layer of 3.7 oz plain weave glass. Got the top and bottom done on Thursday and Friday, this morning I feathers all the raw edges and have applied the first side. I have to wait at least 24 hours to feather the overlap edge on top of the turtle deck and fin LE. My plan is to go flying in the morning and then to the sanding and final side tomorrow evening.

I did pick up a 1.5 gallon laminating resin kit for the mold. I thought it would be a good idea to try some out to make sure it would work as expected. It turned out pretty low viscosity, saturated the cloth really well but the pot life for a 2 oz mix was only about 20 minutes. It was a bit warm 75 degrees. I did manage to get a couple wheel pant halves layed up before the resin started to gel. My normal lay up is a surface layer of 1.4 oz followed by 2 layers of 3.7 oz. the resin did seem to B stage for quite a while. After 3 hours it was still quite pliable and not quite cured enough to trim the edge flush with the mold. I pre heated the oven to 150 then shut it off and placed the molds inside for 1/2 hour. The resin reacted very well to the short post cure and I was able to get the excess glass trimmed and the wheel pants joined. Tomorrow I will de mold the parts and hopefully have a better idea how well the resin system performs.

The low pot life may not be much of an issue for making the mold but could be a big issue with making the fuselage. I have a couple things I will try. The first is to do a lay up when the weather is cooler then a layup with reducing the hardener by 5% ( suggested by the manufacturer ) and I will also try a layup with the mixed resin being slightly thinned with alcohol. I'm not a huge fan of the latter but I have done it with some applications and not had any noticeable ill effects. The biggest issue I have had with that is a thinned resin system seems to interact with PVA and wax to make parts a bit stubborn to get out of tooling. Since all the parts for this project will be layed up on top of a coat of Klass Kote primer, that is a non issue.

Pylonracr

Unfortunately I always have my projects lined up. Final touches on a Cap 232 for my flying partner, should be done mid week. 2 composite 426 race planes for my buddy, a QM40 for the same guy, a 426 plane for me (Thanks Shawn), an F1 Little Toni for me.....................

Shawn, when you mix the resin, put the cup in a bowl of ice to slow it down. As long as it is fairly thin resin you can slow the exotherm dramatically without thickening the resin much. I agree on thinning the resin, I avoid it at all costs. Some resin manufacturers state it is OK, some do not. I have a hard time with the manufacturer saying to reduce catylist by 5% to slow cure. How will this effect the final polymer cross link? What resin is it? I mixed up a few grams of 635 with medium today and at around 65 ambient it was an hour and a half before it gelled off, the stated pot life is 25 minutes at 25C (77F).

Yes Shawn, the Cap is the wing you made me a year ago...........

Scott

speedracerntrixie

My Feedback: (29)

And you say I build slow.........hahahaha.

I had forgotten about the cup in ice thing that you had told me about. That may be a really good idea. Keeping it cold and then when I get it in the mold it will generate much less heat until I can get my lay up done and under vacuum then get it into a hot box. I'm going to have to build a hot box large enough to hold the entire fuselage mold. I will obviously post cure the mold at a slightly higher temp then what I cure the fuselage.

As of right now Im going to go forward with the mold production with the resin I just got by mixing small batches and keeping it cold. The fuselage production at this point will most likely be done in MGS. I am certain that the more working time I have the lighter I can make the fuselage.

Pylonracr

My hot box is pretty simple. I don't know if you paid much attention to it when you were here. It is 1 1/2" foil faced rigid foam insulation. The bottom is on my table saw table and shimmed flat with a couple sheets of paper. I put a sheet of 1/4" glass on top to bag flat stuff to and to bag wings on. The box is more insulation board glued together with liquid nails and pinned with 3" deck screws (1/4" dowels about 3 or 4" long would work. Mine is 2' x 4' about 18" tall. Heat is a 60 watt light bulb on a greenhouse heater thermostat. It will maintain 110F when you can see your breath in my garage overnight.

And I'm not slow i"m thorough. Get it right.................

Scott

Art ARRO

My Feedback: (5)

Scott,
Can you post a photo of your hot box? I'm considering building one for our long winters here in Central NY. Also, where did you get the greenhouse heater thermostat. Any info would be most appreciated.
Regards,
Art ARRO

Pylonracr

Art, I will be happy to. It is in use at the moment, but if you can wait a day I will send you some. I will dig around and find where I got the thermostat as well.

Scott

speedracerntrixie

My Feedback: (29)

Well, some good news. I got that wheel pant out of the mold this morning and it looks great! I am very happy with the quality of the resin system I got. I am going to lay up another part with it later today while chilling the resin as Scott suggests to see if I can stretch the pot life.

Pylonracr

Shawn, there is one more thing I do. Whenever I mix resin I always mix it fairly well and let it rest for a few minutes and mix again. This is fairly standard. If it is even remotely warm in my shop I let it rest in the freezer for 3 to 4 minutes before mixing again, I basically stop the exotherm before it begins. Keep the cup cold while you use it and you should have much longer pot life. Of course you need to pay attention to resin temp if you do this so it doesn't get too cold and not wet out the fabric.

Scott

kenh3497

On thinning resin.... The only place I have ever thinned resin is when glassing over balsa with 3/4 oz. or lighter cloth. In my opinion this thin layer of resin and cloth will give the thinning agent has enough time to evaporate out of the resin before it starts to set. I personally would not take a chance on a layup in the mold making process as the layers will build much faster than the thinning agent can evaporate.

A bit of conjecture on my part about reducing the hardener to increase set times is the downside is it may take a few more moldings to breakin the mold. I'm thinking out loud on this point.

Ken

speedracerntrixie

My Feedback: (29)

As I have been applying the 3.7 oz cloth to the fuselage plug I have been thinning the Tap Marine grade resin by 10%. No issues at all in part to what you are saying Ken. The alcohol has enough time to flash off before the crosslink process is too far done. I reduced the resin for better wet out which saves a bit of time. To be clear, I would never thin the resin when making tooling even though I will not be building up very many layers of cloth at any given time. I think we all at one time or another imagined that once mold production has begun that you need to continue through to the end. Not really nessesarily true. What I plan to do is have the plug all ready to go the night prior, spray on the surface coat ( Klass Kote clear with carbon powder added), then when that tacks up I will run a couple strands of 6K carbon fiber tow into the corner of the plug and parting flange followed by a fillet of epoxy, carbon powder, milled fiber and cabosil. Once that tacks up I will brush on a slurry of epoxy, milled fiber and cabosil and while wet I will put on the surface layer of cloth which will be 3 layers of 1.4 oz cloth. End of day one. I will come back the next day and lay up 4 layers of 3.7 cloth in a 0, 45,135 and 90 degree orientation. Day 3 will be 4 layers of 10 oz cloth in 90, 135, 45, and 0 degree orientation. I will let that sit for a week and then repeat on the other side. Far too often someone will build up too many layers and create an exothermic reaction that not only creates ripples on the mold surface but in most cases makes the realease film inoperable.

speedracerntrixie

My Feedback: (29)

As I have been applying the 3.7 oz cloth to the fuselage plug I have been thinning the Tap Marine grade resin by 10%. No issues at all in part to what you are saying Ken. The alcohol has enough time to flash off before the crosslink process is too far done. I reduced the resin for better wet out which saves a bit of time. To be clear, I would never thin the resin when making tooling even though I will not be building up very many layers of cloth at any given time. I think we all at one time or another imagined that once mold production has begun that you need to continue through to the end. Not really nessesarily true. What I plan to do is have the plug all ready to go the night prior, spray on the surface coat ( Klass Kote clear with carbon powder added), then when that tacks up I will run a couple strands of 6K carbon fiber tow into the corner of the plug and parting flange followed by a fillet of epoxy, carbon powder, milled fiber and cabosil. Once that tacks up I will brush on a slurry of epoxy, milled fiber and cabosil and while wet I will put on the surface layer of cloth which will be 3 layers of 1.4 oz cloth. End of day one. I will come back the next day and lay up 4 layers of 3.7 cloth in a 0, 45,135 and 90 degree orientation. Day 3 will be 4 layers of 10 oz cloth in 90, 135, 45, and 0 degree orientation. I will let that sit for a week and then repeat on the other side. Far too often someone will build up too many layers and create an exothermic reaction that not only creates ripples on the mold surface but in most cases makes the realease film inoperable.

Scott, a couple notes on mixing, at work we have mixing machines, we will weigh out our adhesives in a cup, put the lid on and then select a mixing profile for that specific adhesive and batch size. We are finding that to get consistent results we even have to mix our batches of epoxy the same every time. We have also found that on the occasion when the wrong mixing profile is selected and the epoxy is mixed too long for the batch size that it can reduce the pot life by 50%. That can really suck when bonding material of 4,000 sq in of area. I found that as that applies to what I do at home I had not been mixing my epoxies enough, I now may be overcompensating and mixing too long. I will be doing some more experiments over the next week.

For now the plan is to let the fuse cure for a couple days, maybe carry it around in the car for elevated temp and then start blocking it out on Wednesday afternoon. My goal is to get some primer sprayed on it over the weekend.

Pylonracr

Interesting information on mixing. I had no idea that you could mix resin too much. I was always afraid of not mixing thoroughly enough, which is why I mix - rest - and mix again. I wonder if it applies to all resin systems. I may have to experiment with my 635 and see how much difference it makes in the small batches I usually mix.

Scott

kenh3497

That is interesting about mixing! I've often thought of a tiny mixer that would accept individual cups the would roll the cups much like a miniature concrete mixer. The rolling action should minimize air entrainment and still do a good job of mixing.

I've noticed that when stirring a mix I will see definite lines in the mix as the two parts combine. As the two parts become more thoroughly mixed the lines disappear and the concoction becomes more and more clear. I use the clear appearance that the mixing is complete. I thin stir for a few more seconds for good measure the proceeded to use the mix.


Ken

Pylonracr

Art, here are a few pictures of my hot box. As you can see it is somewhat less than attractive (Shut up Shawn) but it works well. I can't get the center picture to load correctly rotated, but you get the idea. My thermostat is a Surestat 130P which appears to have been replaced by the TS306H. Scroll down the link and you will find it. It is a remote sensor and in one of the pictures you can see the remote probe inside the box.

Greenhouse Controls - Thermostat Controllers from ACF Greenhouses

speedracerntrixie

My Feedback: (29)

So, from 115 miles away you can hear what I am thinking?? Ha ha

Pylonracr

Yup, you are predictable..................

Scott

speedracerntrixie

My Feedback: (29)

Comes with age........... at least you will never guess the planned color scheme for this airplane.