Final Weight: 7.5" LOC Airframe + Soller Composite Fiberglass

[wonderboy]

I am in the process of building a longer upper airframe for my LOC 7.5" Doorknob. I know that the technique of using the Soller Composite fiberglass sleeve is covered pretty well already on the forum, so I'm not going to repeat the steps on how to do it. However, I did want to report out my weights in case anybody is curious. Just to restate what's already been said in those threads: the Soller Composite sleeve works really well and provides a great finished product. I highly recommend it.

A couple of items of note:
I peeled the glassine from the airframe which removes some weight. The airframe as delivered weighed 750g. Peeled it weighed 694g. Also, after wetting out the cloth I squeege all excess resin off/out of the cloth. I use an old hotel room key/credit card for this. I curve the plastic with my fingers to match the curve of the airframe and pull from the center out to each end. I continue doing this until no more resin piles up. Of course, you can overdo this step and make the layup too dry. You'll notice this if the nice brown airframe color stops showing through the cloth and it looks white. This is too dry.

Here were my materials and final weight:

• LOC 7.5" airframe, 30" long, glassine peeled: 694 g
• Soller Composites 7" 10.3 oz fiberglass sleeve: 131 g
• West Systems 105/206: 209 g remaining in layup

FINAL CURED/TRIMMED AIRFRAME WEIGHT: 1034 G

Second note: It took me about 450 g of resin to wet out the cloth (9 pumps). The weight of resin called out above is simply calculated based on the difference in the final weight and the airframe and fiberglass weight. This tells you how much resin can be pulled back out once everything wet out. In my case, over half of the resin came back out. I probably could have been more patient and worked a little more slowly when wetting out the cloth to not have used so much resin. However, I wanted to make sure the resin really was able to soak into the cardboard airframe as well and give a good bond.

Hope this data can help somebody who may be curious about the weights. I do plan on doing a couple more weigh-ins during the body work process. Obviously, I've got a lot of fiberglass weave to fill in. I plan on using thinned Elmers carpenter's wood filler (CWF). I'll report back my weights once this is done and the tube is primed.

 

[BDB]

Thanks for the info. I'm planning to do my first Soller sleeve layup in the near future. Do you hang yours vertically to cure and did you consider using shrink wrap tape?

 

[wonderboy]

I performed the layup horizontally, and then hung it vertically to cure.

When I first built my LOC Doorknob, I used the shrink tube. It gave great results, but took me quite a while to shrink down. I was using an R/C Airplane monokote heat gun. It honestly took me longer to shrink the heat shrink then it did to layup the glass.

I've also helped a friend glass 3 or 4 tubes (same LOC 7.5" airframe) and we heat-shinked those too. My friend had a much better heat gun and it seemed to go much quicker.

This very last time, I was all set to shrink tube it, but it was getting late and I noticed that the layup was sitting perfectly and looked really smooth and nice already. I decided to just let this one be and see how it came out. I DID hang it up vertically though for two reasons.
1: I was working in my basement and with the A/C running it is probably 65 degrees down there. I wanted the resin to have a warmer temp to cure a little faster and perhaps a little more solid. So I moved it to my garage, and hanging it was the easiest way to set it out there.
2: I wanted to make sure that gravity didn't pull the glass off of the tube on the bottom side since I wasn't using the shrink tube.

I definitely think the shrink tube is good, but perhaps not mandatory to get a good result.

If you use it (and if it's your first time) my advice:

• Center the heat shrink on the tube as best you can. I don't mean longitudinally, but rather radially. Try to avoid having to shrink the tube all on one side of the airframe. Make it so that you have to shrink it all the way around the circumference. (not sure if I'm making sense trying to describe this, if not ask and I'll try to clarify)
• Don't Panic! When I first hit the shrink tube with the heat gun my very first time, it crinkled and shrunk into a complete rats nest of mess. I thought I'd ruined it. However, just continue gently heating and shrinking all around the circumference and it WILL smooth out.
• Start in the middle (longitudinally) of the airframe and work to the ends to avoid trapping air.
• You can really put the heat to the tube when there is airframe backing it up. Be careful over any fin cutouts. You can't put nearly the heat into these areas without melting through. The body tube/fiberglass/resin sinks a lot of heat out of the shrink tube and really make it forgiving (very difficult to melt through). As soon as you get to the fin cutouts, WATCH OUT. It will melt VERY easily with nothing backing it up.
• Peel the heat shrink off as soon as you are cured enough to trim (leather stage). My friend let his cure/sit several days (just due to not being able to get to it due to work) and the heat shrink was very difficult to remove.

 

[rhoward99]

I just glassed the 30" tube for my 7.5" LOC Patriot, and I am surprised to see that I had very similar as you! This was my first time ever glassing, BTW.

7.5", 30" long airframe, glassine removed
6" Soller Composite light sleeve, 9.6 Oz
West 105/206 epoxy

I glassed and cured horizontally. I wrapped with Mylar until the leather stage, then cut and removed the excess fabric, and peeled the Mylar off.

I used 9 pumps of epoxy (!) and my final mass was 1035 g, although there is a slight overhang of fabric that still needs to be trimmed.

Two questions:

1) Where did you find shrink that would fit around the airframe?
2) Will you fill the weave, and if so, will you use microballons? If so, what do you recommend?

Thanks for the info!

Regards,
Rick

 

[wonderboy]

Hi Rick

Congrats on not being a fiberglassing newbie anymore!

1) Soller Composite sells the shrink sleeve on their website. https://www.sollercomposites.com/ShrinkTubing.html . I normally use it when I glass the airframe, however, I decided to leave it off on this go-around. In the end, I wish I'd have used it. The tube came out fine, but the ends had a bit of excess epoxy that needed a bit more sanding/filling then the rest of the airframe. My experience with the shrink tube is that it gives a very uniform surface over the entire airframe.

2) I definitely fill the weave of the cloth (it would look pretty bad in my opinion to leave it "raw"). The way I squeegee off all the excess resin really makes the weave of the cloth very pronounced. My technique has been to use alternating layers of filler primer (Rusto Automotive Filler Primer) and Elmers Carpenters Wood Filler (CWF). I apply a slightly thinned CWF with a credit card / bondo spreader. I sand this down until all of the CWF is gone except in the cloth weeve. I repeat this process by first applying a coat of primer and more more CWF (after primer dries), then sanding down until almost all of the CWF and primer are gone. I keep going with this until the light primer coat comes out smooth (no more weave showing). The primer step really shows you when you've got the weave filled. Once I'm able to prime without seeing weave, I'll put the primer on a little heavier and block sand the body tube so that it is nice and flat (along the axis).

The first time I did this, it seemed to only take a couple cycles of prime/fill/sand and then I got a smooth surface. On this last tube, it has seemed to take at least 3 cycles. I just may not have been using the CWF as effectively. I was trying to be very careful not to overdo it to avoid having to sand so much off.

I kept track of some of the weights during this process to see what the contributions were of the different finishing steps.

• Starting point - Glassed and Trimmed Airframe: 1034 g
• 1st Round - CWF filler applied: 1076g / Sanded back down: 1040g
• 1st Round - Primed and Sanded: 1070g
• 2nd Round - Filled, Primed, Sanded: 1078

...lots more in between...

• Final Ready for Paint Weight: 1152g

So, all this filling and priming added 118g to the airframe (4.1 oz) which I figure isn't too bad, although I did just calculate it at 10% of the overall final weight which isn't trivial.

 

[jimzcatz]

Sollar stuff rocks, but I CAN'T believe people insist on peeling glassine!!!! A simple damp sponge will remove it without having to cut anything. Damp, not soaking wet. It's not going to hurt your paper tubes.

 

[rharshberger]

Sollar stuff rocks, but I CAN'T believe people insist on peeling glassine!!!! A simple damp sponge will remove it without having to cut anything. Damp, not soaking wet. It's not going to hurt your paper tubes.

Lots of people are unaware that glassine is just paper, to be exact supercalendared paper ie rolled at very high pressure which creates a glossy finish and water will remove said glossy finish.

 

[wonderboy]

Do you view the peeling as a problem or a negative, other than the perceived difficulty in accomplishing it?

For me, peeling the glassine is SUPER simple and typically doesn't require any cutting other than using the edge of a knife just get a nice clean start on the peel. Once started, the peel goes incredibly easily and quickly. I've read about, but haven't tried the "damp rag" technique. I find the peeling technique leaves a really nice raw surface that accepts the laminating epoxy very well.

My guess is that I can peel the tube quicker than you can "damp rag" it off... (No, that's not a challenge)

 

[rhoward99]

I've tried the damp rag technique to remove the glassine sheen on other projects, and it worked. And, the remaining finish even had some of the "fuzziness" feel that you get when you peel it completely off. My primary reason for removing it (as in my above post) is because that is how Soller suggests prepping the tube when glassing it using their socks.

 

[wonderboy]

I'll have to try that technique one of these times just to expand the repertoire.

 

[pathtouch]

Just adding some data incase others come to the thread to estimate weights. I used Total Boat epoxy and two wraps of 6oz fiberglass on 7.5" LOC tubes and got the following weights. Converting to grams my 30" tube came in around 1100g which is a little heavier wonderboy and rhoward99 but I suppose I have a little more cloth.