edwarda10pilot

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Richard:
I am not trying to persuade you from using the veil but my experience with it would sugest that it might take a fair amount of urethane to "fill" the weave. You might be able to apply a very thin coat of urethane and then use something like a sandable primer to fill the weave. The problem is that as with glass cloth, you must be very careful not to sand thru the application coat of urethane or epoxy as this will cause a bunch of little fibers to pop up and the only way to prevent a sandpaper like final finish is to apply more of the urethane.

i have talked with others that have used the West Systems and it is avery bit as capable as the System Three. There are those that have sugested that to save weight, one should reduce the epoxy by 50% but I have tried this and I was not happy with the results. With PPG and previously with the Dupont clear urethanes, I have found that if you do not add enough catalyst it might never harden. You can over catalyze it and it will harde but under catalyzed it might never cure. It will seem as though it is hard but it will not stand up to fuel as well as the correctly catalyzed clear. I do not have any experience with any urethanes other than PPG and Dupont.

What brand of urethane are you using? Please let us know how the process works. If you don't mind, a few lessons learned on painting. If flying a glow plane the you should make the base coat (whatever the primary color is) a single stage paint (this means that the paint does not require a clear coat. Your paint friend will understand the difference between single stage and two stage). A single stage paint as mentioned is one that does not require a clear coat to seal it while a two stage paint is a base coat (the color coat) and the clear coat which seals the base coat. Using a single stage paint that has had a catalyst added to it will seal the wood and veil from the fuel. You acn then use the color froma two stage paint for all of the trim colors. The advantage to this is that it is a lot like a lacquer in that it dries very quickly and can be masked off for the next trim color fairly quickly (usually less than an hour). This allows you to spary a number of trim colors on the plane very quickly (I have done five colors in one day using two stage). Then once the paint has dried for the recommended time, you can apply a clear coat to seal everything. One thing to note is that when you spray a single stage color or the two stage color you must thin the paint to spary it. When yo do this, roughly half of the paint is thinner which evaporates. When you spary the clear coat on you do not reduce it so be careful in that whatever the clear coat weighs when you spray it n is the amount of weight you will add to the plane (been there, done that). For my clear coat, I lightly mist on one coat, let it "flash" for about 15 minutes and then I put a little heavier coat on, but you must be careful not to put too much on. Attached are a couple of photos of two pattern planes that are glassed and painted using the method described. Just FYI, the third photo is of a Sommenzini Yak that is ultracoat white and all of the other colors are PPG paint (single stage).

I see that you live in Colorado Springs. I used to live in Denver (1990 to 1995) and used to drive to Colorado Springs to fly with Greg Moore and Ivan Munninghoff. Ivan, Herb Heaton (from the Springs) Dean Lassek (from Denver) and I did four of the very first ducted fan big birds. I was heavily into jets at the time and we decided to build a 120" span A-10 designed by a guy by the Name of Josh Harel. THe planes had OS 91's dynamax fans and weighed between 43 and 53 pounds and flying at 7000 or 5600 ft (Denver) was a real challenge. I also flew one of my Tom Cook Jet Model products F-4 at the local airport. That plane at 33 lbs was a real handful until Ivan and I determined tha thte CG was 1.5" too far aft (shown incorrectly on the plans). Once we recalculated the CG the plane was fun to fly but very difficult to take off and land. Sorry to get off thread but I thought I would ask if you know Greg Moore?

Ed

kingaltair

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Ed....What kind of glass cloth, and "systemthree" epoxy would you recommend for glassing the wing joint in a built-up wing? I have a built-up King Altair wing, (74" span) on the board right now. It is also produced by Jeff at "Classic R/C" and is built very much like the Simla wing.

Thanks

Duane

edwarda10pilot

My Feedback: (3)

Duane:

A built up wing is alittle different than a foam wing in that a built up wing typically had a plywood dihedral brace which tends to add great deal of strength to the wing. When I glass the center of a builtup wing I typically use 3 or 4 oz cloth that is about 3" wide. For a foam wing, there is usually a very small dihedral brace or none at all and consequently, the center section glue joint and cloth is terribly important. What I have done before is to use 3 or 4 oz cloth about 3 or 4" wide across the wing center section. Some people have suggested 6 oz cloth but I don't think that heavy a cloth is required. I have found that traditional epoxies (the 5, 15 and 30 minute stuff) are too viscous to flow thru the cloth and peneterate the wood deeply enough to form a strong joint. I use either the system 3 clear coat (or the West System equivalent) as it is fairly thin and penetrates very well or use the Zap Zpoxy. IF neither of these are available, you can use the 30 minute epoxy and thin it with denatured alcohol. It is important that you DO NOT use any of the Isopropyl alcohols as they have some amounts of water in them. Any water in the thinning agent will prevent the epoxy from hardening completely. I have also used acetone to thin epoxy but you must thin the epoxyacetone combo in a glass container as it will melt anything else. Denatured alcohol and acetone are available in quart cans from Lowes or Home Depot. If you choose to thin the 30 minute epoxy and although it is a bit of an effort and takes a little additonal time, I would mix up a small test batch and ensure that it dries and hardens. Additionally, you also want to test the strength of the attachment between the cloth and the wood. If you try to pull the cloth off the wood and it comes off without any of the wood grains on the cloth, the joint is not structurally sound. This is important since it IS the strength of the wing joint. Please also remember that the cloth across the wing center section joint is done against bare wood and has not had balsa rite or clear dope applied (as I mentioned previously). Once the cloth is applied to the center section then the film or glass can be applied.

I hope that everyone who reads my posts understand that what I am offering here are simply my experiences and opinions. I realize that everyone has different experiences and there are many different ways to do things. My experiences is based on more than 50 years of building free flights, control line and pattern models but it is just that, my experience and certainly not the only way to do something. I say this because I have made suggestions on RCU threads before and been criticized for my approach so I just want all to know that I am simply offering my life experiences.

Hope this has been helpful. If you choose to discuss things that you don't care to make a post on then contact me at: [email protected] and I will try to help as best I can.

Ed

rg1911

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Ed,

I confess that I, too, am a bit concerned about how much urethane or epoxy the carbon will suck up. It is, however, very thin (you can see through it), so I thought I'd give it a try. I'll also weigh the test piece before and after.

The brand of 2-part urethane I found in town is Original KlearKote number 5185. It has a VOC (whatever that is) of 4.4. The hardener is the medium, number 5187. It's mixed 4-to-1. Not sure how long it takes to cure; the label is printed in 2-point type and not hugely informative. I'll check the web for more info.

If you know Larry Laughlin, he's about the only club member who seems to know how to paint, so I was going to approach him for lessons if the Ultracote covering doesn't work.

Yup, I know Greg Moore. He's been doing a fair amount of writing for one of the magazines and often is testing a new plane seconds before the editorial deadline.

Ivan was one of the finest gentlemen I've know. Less than a month before he died, he was teaching me how to do consecutive slow rolls. (And kicking me when I pooched things. An effective teaching mechanism.) Never drank or smoked. The only reason for his lung cancer we can think of is a lifetime spent sanding glass and painting without a mask. I think he also was the last "builder" the club had. ARFs have pretty much taken over; so there really is no-one here I can hit up for help. Thank goodness for this thread!

Ivan and Dan Brunson did a fair amount of work together, and Ivan's son, Paul, was Dan's pilot-of-choice when he did aerial photography. Dan now owns the only good hobby shop in town, Pikes Peak RC Hobbies. He and his dad converted their photo studio building, which they had owned since the 50's, so Dan's not paying rent or a lease. I can walk out the door for less than ordering from Tower. I'll have to ask Dan if he remembers the A-10.

Cheers,
Richard

edwarda10pilot

My Feedback: (3)

I thought I would offer one additional comment regarding finishing. In one of my previous post on this thread I showed a picture of a Sommenzini Yak that I had stripped and recovered with white Ultrocoat. The other colors on the plane (red, silver and black) are all PPG single stage paints. I have seen some post by people asking how to prepare film covering for paint and if there is interest, I can make a post explaining the process. I know that this thread is about the Simla build so I do not wish to hijack the thread.

Ed

edwarda10pilot

My Feedback: (3)

Richard:

I am not familiar with the urethane you have so I don't think that I can be of much assistance. If you choose to have someone paint the plane, do not use an automobile paint and body guy (unless they are modelers) since they tend to put a lot of paint on the model. If Lary can not paintthe model, let me know and I have a good friend in Dallas that has apinted a lot of models and he may be able to help. Send me an e-mail (no PM's please) and I will give you his contact info.

I agree that Ivan was one of the nicest people I have had the pleasure of knowing. He was always willing to help. I remeber him telling many stories (some not appropriate for this family type forum) about training people how to fly full scale fighters. He had some interesting and also at times very funny stories about teaching the south Vietnamese to fly the absolutely huge T-28. I am fortunate to have a friend here in San Antonio who is a lot like Ivan in that he is retired Air Force. Additionally he is an aero engineer so I can bounce design questions off of him (much as I did with Ivan). The guy here in town is also the holder of two DFC's (distinguished flying cross) medals for flying a C-130 into Khe San (SP) during the Tet Offensive. He flew 1300 mission in C-130's in Vietnam and is truly interesting individual to talk to.

Let me know if I can help and I will do my best. If any of you wish to "talk' (as in on the phone), send me an e-mail ([email protected]) and I will provide my home phone number. In the body of any e-mails please put something like " airplane question" or similar so I will not delete it as spam.

Ed

rg1911

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Ed,

I wouldn't consider any tips on finishing as hijacking the thread.

Would anyone else?

Cheers,
Richard

rg1911

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A few posts ago I reported that, trying to gain a bit more working time, I ended up not adding enough hardener to the filler I'm using, so it didn't cure completely. I finally thought to call the Bondo tech support, and a helpful gentleman in Atlanta suggested I try acetone.

That did, indeed, do the trick and I was able to remove all the uncured filler. (The only other choices were to make a new rudder or attack the filler with hammer and chisel.) The acetone also removed the surrounding primer, but did not affect the existing cured filler.

Cheers,
Richard

billberry189

My Feedback: (1)

Ed,

I would tend to agree with your comment about an auto body and paint guy applying too much paint to a model; however, since I began modeling about ten years before I became an auto body and paint guy I am a bit more sensitive to the weight issues involved in painting an R/C model. True, I never have been as concerned with weightas I am with this build and much of what I am using is somewhat experimental as far as weight is concerned. That having been said, the process that I am using for my Simla has added only 2.5 ozs. to the bare balsa fuselage. That includes 0.5 oz fiberglass, two sanded application urethane clearcoats for the glass, and two finish urethane clear coats. I thinned all four clear coats 10% with urethane reducer, and mixed clear to catalyst at 4:1. I suspect that after finish sanding that 2.5 oz weight will drop by 0.5 to 0.75 ozs.

I also lean toward a base coat/clear coat system for the reasons you stated earlier. One can apply multiple color patterns in a relatively short period of time with very little weight build up since they are thinned at about 1:1 and you get 50% flash off of the reducer. The break lines from color tocolorare also easier to eliminate with the base/clear system. And since I finish sand and buff my paint jobs even more material is removed without disturbing the color coats. I like to think of it as custom painting on a diet.LOL

I, in no way, am claiming that this is a superior method of finishing an R/C model. It is just the way that I like to do it and now I am experimenting with ways to make it lighter. I seriously doubt that I will ever compete in pattern flying(ie-contest flying) that will require me to have the absolutely lightest plane that I can come by. For me, the weight issue is more about the challenge than the necessity.

Bill

rg1911

My Feedback: (1)

Just a quick comment here about the KlearKote urethane and catalyst. It is nasty stuff. Treating it like I do small amounts of regular paint, I mixed up a small test batch in the basement and applied it to a test piece. The entire basement is now just about uninhabitable and I have a headache and every window open.

Everything is now outside.

I used a small plastic container as a measure, and the urethane/catalyst ate through it in about a minute.

I have learned my lesson!

Richard

kingaltair

My Feedback: (4)

REMEMBER ...We build models for FUN...right?? That's what I tell myself every time I drop a little, (valuable and irreplacable) screw, bolt or other piece on the floor of my shop, and it always bounces into some location where I can't find it. I ask myself WHY I'm doing this?? Answer....I can't do a loop with a stamp collection.

Another thing...why is it that most of the time you can't quite reach the area you're forced to work in? But that's another issue.

Duane

rg1911

My Feedback: (1)

Duane,

One word: Murphy.

But your comment about small spaces got me thinking that now, while spaces are still open, would be a good time to think about servo placement and linkages in the fuse. I was planning on pull-pull on the rudder and using the internal control horn for the elevator. With the large engine and mount, the throttle and nose-gear linkages could be tough. So I don't reinvent the wheel, are there any photos of successful setups?

And the way Bill is storming along, I suspect I'll be tail-end Charlie on this build. So let me thank everyone for all the help they've given me. I'd still be puzzling over the plans and directions without the contributors on this thread. As it is, I actually can envision the day when my Simla flies.

Cheers,
Richard

billberry189

My Feedback: (1)

Richard,

Nasty stuff indeed. I have been doing this urethane finishing for so long that I almost have become immune to the odor. However that does not mean that I don't take steps to make sure that I use it ina well ventilated area. I apologize for not mentioning that I do all my urethane procedures outside, and that I let it set up while it is outside before I bring it back into the house. My Bad!

Today I'm doing a little finish sanding on the fuse and tail feathers before painting while I'm waiting for my wing sheeting to arrive. According to UPS, that should be tomorrow.


Bill


PS-In over forty years of working with these catalyzed materials I cannot remember ever having a hardening problem. But that doesn't mean that I won't in the future so thanks for the research tip on the acetone cure.

rg1911

My Feedback: (1)

I'm going to add the second coat on the second side of the test piece, but right now, my impression is that the carbon veil is soaking up a lot of the urethane. (I even had put down a seal coating on the bare balsa to start.) According to the information on the web site, it won't be ready for sanding until tomorrow, but Ed probably is right that the weave will need to be filled with something, such as sandable primer. Or I'll need to go back to glass. Or even, much as I hate to say it, make sure the balsa surfaces are perfectly smooth and use only the Ultracote.

Well, I have been using this project to test several ideas. I can't expect all of them to work perfectly.

Cheers,
Richard

kingaltair

My Feedback: (4)

Cheer up Richard..Jeff tells me there are up to 50 Simla(s) already spoken for, and people are receiving theirs almost every day, (probably), so you are on the cutting edge, being only the second Simla built since the prototypes that we know about. Naturally ALL the Simla builders should view this thread because it contains so much indispensable "good stuff". This thread is a "DO NOT MISS" for all Simla builders.

We need to get Jeff to "guest-visit" this thread and comment...I hope he'd approve. I don't think we've said any "bad stuff" about him.
Duane

billberry189

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Ditto to all that. Remember, Richard, I'm the exception rather than the rule here since I am retired, single, with agrown child and 24/7 to devote to whatever. Maybe I should go get a job so I can slow down a bit.Just kidding there. Although, the added income would not hurt. It is all in good fun and should stay that way. And consider this. How long I'm going have to wait before we all get together after I have finished my build. Who knows, with thatmuch time I might windup crashing it beforethe event andhave to build another one.

kingaltair

My Feedback: (4)

It took me six months, and that was "pushing myself" somewhat from time to time. Still "billberry" is "slower" than he said he'd be at first...you're already at a month. I knew you couldn't do it in two weeks, (unless you had those unpaid "elves" of yours).

It took me two weeks just to cover and paint mine. The radio and linkages take a while as well.

Still, you are the fastest builder I've ever seen...bar none. Waiting around for stuff to arrive probably has slowed you some.

Duane

rg1911

My Feedback: (1)

And we're lucky that Bill has to wait 12 hours for his urethane to cure before sanding. (At least that's what my instructions say.) He probably sprays his parts with kicker first, because thin CA is just too slow.

I think Bill's idea that he should get a job so he has to slow down is a good one.

Cheers,
Richard

billberry189

My Feedback: (1)

Duane and Richard,

You are very funny guys!Humor has a way of curing all things bad. It's not often that one can be so well informed and laugh at the same time. What a great thread!!!! I have no doubt that when we can all get together it will be a fun filled time!

Bill

billberry189

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Duane,

For what it is worth, I usually install all the necessary hardware for the radio during the build, so that when I am done painting it only takes a short time to have the servos, receiver, switches, and battery buttoned up and ready to go. It's just the way I plan things out while I am building. That's why I asked for an interior photo earlier in the build thread. I alsoinstall the servos and receiver on one board to make installing and removing them quick and easy. That leaves theplacement of thebatteries to adjust the CG. It's a bit like modular construction.

kingaltair

My Feedback: (4)

Did I provide you with one from my prototype, or did I refer you to Kevin's...his is neater than mine anyway, but I have been meaning to take pictures of the hatches, and include a couple interior shots.

I still need to discuss those wingtips...they will present a bit of a surprise.[X(]

Duane

billberry189

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Well, even though hurricane Irene is long gone and only whispered by the Florida coast, it has managed to have an effect on my Simla build. I was supposed to receive my wing sheeting today, but due to transportation difficulties for which Irene was completely resposible, I won't receive my sheeting until late tommorow. Oh well, that should make you guys happy. One more day with an anchor tied to my tail.

On the other hand, I was poking around my old stuff and found an old Top Flite Taurus wing kit. Most of it had been scavenged except for the ribs. Sooooo, it occurred to me that I could use the left over Simla wing sheeting from Jeff's kit to build a Taurus fuselage, pick up a few wing spars and wing tips, and voila, a Taurus in the making. Whay do you think? 

rg1911

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A great idea, Bill. Anything to slow down your Simla build.

rg1911

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Results of a limited test of .3-ounce carbon veil with 2-part urethane and Ultracote.

I covered a relatively small piece of scrap balsa on two sides with the veil and urethane. Before treatment, the balsa plus the veil registered as .2 ounces on my digital postal scale. (In hindsight, I probably would have gotten a more useful reading if I had set the scale to grams.)

I applied a base coat to the balsa, followed by the veil with 2 coats of urethane on one side and three coats on the other side.

After 24 hours, I sanded one side smooth using 220-grit paper. There was no indication that I had sanded into the veil (hard to tell with black), so I deliberately sanded well into the veil on the second side. That side also sanded smooth with no indication of broken hairs, even under magnification.

The weight of the test piece after all this was .3 ounces. Although that is a 50-percent increase, I would want a larger test sample and a more careful application of the urethane before I accepted that result.

I then applied a scrap of Ultracote to the test piece. No problems were experienced, but I noted that the surface is *slightly* rough or pebbly in appearance, and there is no way the Ultracote will ever come off. I suspect that the cause of the appearance is having not sanded the test piece absolutely smooth. I also suspect that one way to deal with this is to seal the edges and then tighten the Ultracote with a heat gun, rather than pressing it into the surface.

I'll perform a larger test now that I've pieced together the jigsaw puzzle that the front half of my Stik became after it lost the battle with a pole.

My tentative conclusion is that the carbon veil plus urethane plus Ultracote will work.

Cheers,
Richard

rg1911

My Feedback: (1)

Bill,

Since it's clear that I'll need to apply the urethane outside, this weekend I will build the stand you kindly described and photographed. Based on your experience, is there an optimum level at which the fuse/plane should be placed? For instance, right at eye level? X-inches below eye-level? Somewhere around my belt line?

Did you glue the parts together or does the stand just rely on tight fits?

Thank you,
Richard