Composite Building Newsgroup

[Eckertwa]

I am building a Jabiru J230 but I am pretty inexperinced with fiberglass. Unfortunately, there isn't much of a support group for Jabiru builders. Can anyone recommend a newsgroup or other resource for composite building?

Wayne

[Frank Giger]

The KR community is pretty large and from everything I've heard really helpful when it comes to matters of laying down glass.

[1600vw]

I am in the process of learning this myself. I lean here or look to these for a lot of help. If you do not know about these wibinars you are in for some very good info. I enjoy watching them if for no other reason then to learn something.


http://eaavideo.org/video.aspx?v=3618162628001

Tony

[Bob H]

I've done lots of composite mfg work and can probably answer questions. Built a Pulsar. If you want hands on direction, EAA classes are good. If you want more of a technical education, Andy Marshall's book "Composite Basics" is good.

[Eckertwa]

Hello Bob,

One of my big hang ups is the finishing process. I've taken the EAA's two day seminar on composites and the short one at Oshkosh (a couple of times). These were great for the learning the basics of layups and joints but they didn't go over the finishing.

One of the first steps in my Jabiru construction manual was to sand down the interioir of the pre made fuselage. They stated this is needed to clean up any rough fiberglass that might cut or scratch you in the building process. I couldn't help myself; I turned a three hour sanding task into 30 hours of turd polishing.

I'm also concerned that I might leave things too rough and regret it when it is time to do the finishing.

As as you can imagine, not knowing where I should be on the "make it smooth" or "slap it together" scale has me somewhat paralyzed in my kit building progress. Any advice?

I also have questions about: fuel tanks, hard points, trim tabs, and other misc items.

Ill look into getting Andy Marshall's book.

[Byron J. Covey]

One of my big hang ups is the finishing process. I've taken the EAA's two day seminar on composites and the short one at Oshkosh (a couple of times). These were great for the learning the basics of layups and joints but they didn't go over the finishing.

http://curedcomposites.com/finish.html


BJC

[griffin800]

Good reply, but for the previous post, it's ok to sand off bits of fiberglass weave that sticks up from the surface. It's not ok to sand into the weave of the cloth or you'll reduce the strength of the glass.

Bill H.

[cub builder]

Hello Bob,

One of my big hang ups is the finishing process. I've taken the EAA's two day seminar on composites and the short one at Oshkosh (a couple of times). These were great for the learning the basics of layups and joints but they didn't go over the finishing.

One of the first steps in my Jabiru construction manual was to sand down the interioir of the pre made fuselage. They stated this is needed to clean up any rough fiberglass that might cut or scratch you in the building process. I couldn't help myself; I turned a three hour sanding task into 30 hours of turd polishing.

I'm also concerned that I might leave things too rough and regret it when it is time to do the finishing.

As as you can imagine, not knowing where I should be on the "make it smooth" or "slap it together" scale has me somewhat paralyzed in my kit building progress. Any advice?

I also have questions about: fuel tanks, hard points, trim tabs, and other misc items.

Ill look into getting Andy Marshall's book.

As previously mentioned, avoid sanding into the weave of the fabric.

Be fearless when working with fiberglass. There is nothing you can screw up so badly that you can't grind it off and build it up again.

When finishing, use a cheap rattle can of spray on primer to check your work. If you think it looks good, or you want to see how good (or bad) it looks, spray a light coat of cheap primer over the part. All the imperfections will suddenly come into focus. You're going to sand off the primer anyway, so there is no need to use an expensive primer.

Pinholes are easy. I brush on a coat of really cheap Rustoleum high fill primer bought at the local autoparts store. Then I brush on some more while it's still wet. Then I brush on some more again while it's still wet until I have a half dried slurry of primer. I squeegee the primer back and forth over the pinholes until it starts to get too thick to work. Let dry for 30 minutes or so, then wet sand with 220 wet. Again, expensive primer isn't required as you will sand off everything except the primer that is left filling the pinholes. After wet sanding, shoot a light coat of cheap rattle can primer as it will show any remaining pinholes. Wet sand the cheap primer back off, and repeat the process if you still have any pinholes. It's inexpensive, and quick.

Finish on fiberglass is never perfect. You just reach a point where you are tired of sanding and want to fly, so you prime and paint.

Feel free to peruse my personal web site (http://jeffsplanes.com) as there are some areas that cover a lot of glass work that I've done when modifying the KR that I built many years ago. I never put the original photos on line from when I built the plane as photos were still done with film back then, so I didn't take as many and never scanned the ones I have in for the web site. :D

-Cub Builder

[Byron J. Covey]

Feel free to peruse my personal web site (http://jeffsplanes.com) as there are some areas that cover a lot of glass work that I've done when modifying the KR that I built many years ago.

-Cub Builder

Nice web site, with lots of interesting items.

Thanks, Cub Builder.


BJC

[Eckertwa]

Thanks for the two websites. Both will be very helpful.

I've ordered the Composite Basics book as well as Composite Materials: Fabrication Handbook #1. I found the later on the EAA website.

[griffin800]

>>Finish on fiberglass is never perfect. <<

With composite finishing, learn from the boat builders and the Corvette guys. Lots of time has been spent by both learning to properly finish fiberglass. It can look better than any other construction material if you learn how. Lots of info online too.

Btw, auto shop supply houses, most decent sized cities have them and online too, are a great place to purchase finishing supplies inexpensively.

Bill H.

[foolonthehill]

My goodness, I wouldn't advise learning from the Corvette guys! Maybe they've improved over the years, but my experience with them is they're a bunch of tiger hair throwin' bondo butchers.
I'm not the last word in composites by a long shot, but I did work for about 30 years at Rockwell International, and then Boeing; after they bought Rockwell's aerospace division, in advanced composites.
I built the Space Shuttle, B-1B bomber, and a lot of other stuff before I went out on my own.
Currently, I build composite components for Jabiru, North America, and I build the entire airframe for the Arion Lightning aircraft, and a number of other parts, pieces, cowls, etc, for other aircraft companies.
I'm also co-author on a couple of composite patents.
If I can help you out, let me know. I don't have a web page developed yet, but we do have a FB page, AM Composites, if you'd like to take a look there.

[griffin800]

My goodness, I wouldn't advise learning from the Corvette guys! Maybe they've improved over the years, but my experience with them is they're a bunch of tiger hair throwin' bondo butchers.
I'm not the last word in composites by a long shot, but I did work for about 30 years at Rockwell International, and then Boeing; after they bought Rockwell's aerospace division, in advanced composites.
I built the Space Shuttle, B-1B bomber, and a lot of other stuff before I went out on my own.
Currently, I build composite components for Jabiru, North America, and I build the entire airframe for the Arion Lightning aircraft, and a number of other parts, pieces, cowls, etc, for other aircraft companies.
I'm also co-author on a couple of composite patents.
If I can help you out, let me know. I don't have a web page developed yet, but we do have a FB page, AM Composites, if you'd like to take a look there.

I'm not saying learning from how Corvettes are built, hardly, really poor quality, I am saying learning from the guys that refinish Corvettes. Some of those spending $80k for a car want it to look like it's worth that much.

Bill H.

[Byron J. Covey]

Beautiful, smooth, glistening finishes (as seen on many auto restorations) can be an indication of an overly heavy finish. The airplane builders who achieve that degree of finish without lots of filler are the ones that impress me.


BJC

[cub builder]

The point I apparently failed make is that with repeated filling and sanding, the finish can be very high quality. But the builder will always see imperfections in his own work that nobody else will notice. The amateur builder can quickly build to a nice finish, but if you want perfection, it takes a lot longer as there will always be minor imperfections you could fix. I'd rather paint and fly than spend the next year sanding and filling repeatedly. Thus the statement about getting tired of sanding and filling in search of perfection, so you paint and fly. The point at where you decide to stop sanding and start shooting paint is different for every builder. But I would bet that every single builder that has built a glass plane could walk up to their plane and point out at least 10 imperfections or mistakes they made while finishing, even though very few people would notice any of them.

My own glass plane is full of imperfections. But it's good enough to have garnered a number of awards at numerous fly-ins. While the awards are a nice complement to my work and greatly appreciated, they were never my goal.

-Cub Builder

Perfection is the enemy of good enough. :D

[George Sychrovsky]

If you are filling and sanding repeatedly it means you are doing it wrong.

[griffin800]

>> But the builder will always see imperfections in his own work that nobody else will notice. <<

Oh yes, absolutely. I know where the flaws are and see them all the time, no one else ever sees them.

A problem with composites, much like other building methods is the finish you'll easily obtain results in the work you've done previously. If you're very careful while you're laying up the glass, you'll have a much better surface to finish later and a much easier job getting that finish. If you're in a rush and sloppy with the glass, you can still get a decent finish but you'll pay for your rush job getting that finish.

Bill H.

[Eckertwa]

Hello Cub Builder,

I really liked your KR website but what I am most interested in was your elevator trim tab. I am planning to put a trim tab similar to that on my Jabiru.

I was planning to put the servo entirely in my elevator but your example of making it exposed and flush mount is intriguing. Is that working well? I may still mount it inside my elevator but I haven't figured out the mounting yet. I was thinking of making it accessible by removing the trim tab to expose a pocket but I haven't figured out how to mount it. I want to avoid any exterior screws or hardware if possible.

What material do you recomend for the trim horn? From the looks of the photo, it looks like you used metal. I assume I will try to layup the horn but I am not sure how I will do it yet. Any suggestions?


Wayne

[Eckertwa]

http://curedcomposites.com/finish.html


BJC

I really enjoyed reading the webpage on finishing composites. It made the process sound very straight forward.

With my Jabiru, the interior of the cabin is raw cloth and epoxy, no topcoat. The manufacturer recommends covering the entire interior with carpet. I don't like this option and would like to finish the epoxy in most areas. Is the micro solution the best option for filling the fabric weave and overlaps? There are a lot of tight, inside turns that don't have a lot of access. Sanding the fiberglass burs was hard enough, I imagine sanding micro solution smooth in these areas will be very challenging.

Thoughts and comments?

[Marc Zeitlin]

The manufacturer recommends covering the entire interior with carpet. I don't like this option and would like to finish the epoxy in most areas. Is the micro solution the best option for filling the fabric weave and overlaps?Carpet is heavy.

You've got a few options. Here are two.

Rough up the surface with 80 grit, then apply West 105/206 and micro in a relatively thin layer. But only do this in places where the surface will be visible AFTER all the upholstery and access panels are installed, as well as headliner, etc. IOW, ONLY where the surface will be visible in the finished airplane. This will minimize the surface area to deal with. Then sand the micro, prime and paint.

Alternatively, you can just rough up the surfaces (same surfaces as described above) and then paint with Zolatone or the functional equivalent, and a clearcoat. Some of the spatter paints are very nice, and do a good job of hiding the weave. If you're trying to win Grand Champion at OSH, this won't be good enough, but if you just want something that looks good and doesn't take forever to do, it's fine.

My $0.02.

[cub builder]

Hello Cub Builder,

I really liked your KR website but what I am most interested in was your elevator trim tab. I am planning to put a trim tab similar to that on my Jabiru.

I was planning to put the servo entirely in my elevator but your example of making it exposed and flush mount is intriguing. Is that working well? I may still mount it inside my elevator but I haven't figured out the mounting yet. I was thinking of making it accessible by removing the trim tab to expose a pocket but I haven't figured out how to mount it. I want to avoid any exterior screws or hardware if possible.

What material do you recomend for the trim horn? From the looks of the photo, it looks like you used metal. I assume I will try to layup the horn but I am not sure how I will do it yet. Any suggestions?


Wayne

Wayne,

I mounted the servo in the elevator on both of my planes. If you look at the last page of the SuperCub project, you'll see virtually the same mod done to both planes. Just that the Supercub was done with 4130 steel and fabric rather than wood and glass. The SuperCub needed the trim control installed on both sticks, so includes the Ray Allen relay deck in the installation and a couple of stick handles with the chinaman hat trim button along with a PTT button. The Ray Allen Servo actuated trim tabs work well in both planes.

I used a strip of 4130 steel with a radius bend at the bottom and a couple of holes drilled in the bottom, then bedded in glass fibers and resin for the trim horn. I did the same with the SuperCub except that the 4130 trim horn is welded in.

-Cub Builder

[Yellowhammer]

Bob,
I am about to start building my Pulsar kit that I acquired from a gentleman who has completed less than 10% of the build. Aero Designs kit # 277 I believe. WOuld you be willing to allow me to cross reference you from time to time?
Thanks

[Bob H]

Sure. Contact me at bobh5@earthlink.net.

[Yellowhammer]

Yes sir will do and thank you very much.