The Art of Tissuing
 

I mentioned tissuing in another thread and really recommend it. You can't beat using Jap tissue and dope to cover large balsa surfaces. The work is minimal and the surface is smooth and strong. I initially used Jap tissue on competition BG's, but it works great on sport models as well. I use Bob Park's instructions from the October 1970 issue of Model Rocketry magazine. You can download it from Sven's Ninfinger.org site.

I still have lots of high quality Japanese tissue left over from my "stick and tissue" FF airplane days. I would like an alternative to the dope though. That stuff really stinks and you need a well ventilated are when using it.

alternative to the dope
 

As long as you are not using it on an airplane. 70% white glue to 30% water will work. Its too heavy for use on stick and tissue planes but for rockets it not enough of a weight problem. Sometimes you will have to play with mixture depending on brand of glue though.

You could try using a thinned down white glue for the leading and trailing edges and a glue stick (the purple ones that dry clear) for the fin surface. I use the glue sticks to adhere the tissue to the wings and the fuselage of all of my ff planes. It works quite nicely without the wrinkling you may get from using the thinned white glue on a large flat surface.

EJS

Thanks for the tip. I happen to have one of those glue sticks so I'll give it a try.

Another possibility that I picked up in my model airplane days is light glass cloth.

Get some 2oz glass cloth, a bottle of 3M (or similar) spray adhesive, a bottle of thin cyano glue, some laminating epoxy resin, some paper towels, and some 200 grit sandpaper.

Lightly spray the balsa with the spray adhesive. Cut some glass cloth to size. Stick the glass cloth onto the balsa (it should lightly stick due to the spray adhesive). Make sure the glass is touching the balsa (ie no "bubbles"). Dribble on enough cyano to wet the cloth. Let cure. Mix epoxy and apply to glass. Blot out excess epoxy. Let epoxy cure. Sand lightly with 200 grit paper, finish using your favorite method.

This method adds very little weight but adds a lot of "toughness" to the balsa structure.

IIRC I picked it up in "Flying Models" magazine back in 1989 or so.

Welcome aboard, dosco!

Good to see a fellow winger with the craving for BP...

I'd be careful about using 2 oz cloth... :eek:

You might prefer to use 0.75 oz, or even 0.6 oz, cloth instead. 2 oz is very heavy stuff, and soaks up resin like a sponge. Might be OK for models using, say, I-N power ranges, but not for 1/2A - F. :rolleyes:

Alternatives would be silk, or even silkspan. ;)

Craig McGraw

Good point. I undoubtedly mis-remembered. D'oh!

Thanks for the correction! I indeed was thinking the light-stuff. Apologies.

No problem. In truth, though, for what we do with these models, I think FG cloth, even the lightweight stuff, is horribly overkill for the weight penalty it introduces, not to mention the extra work it requires. I know some builders like to use epoxy sparingly for certain applications, like fin attachment or motor mounting, but my opinion is it's just too bloody heavy. Especially when used at the tail of the rocket. :(

I've seen models from an Alpha on up that had been "glassed". Nice finishes, but twice the mass. They make great hanger queens... :eek:

On high-performance "C", "D", and up models, I might agree that a small strip of 1 oz or 2 oz cloth at the base of the fins, used strictly as a reinforcement device, is cheap insurance against a fin detachment. I might also agree that the use of silkspan on the large surfaces of the fins applied with clear dope -- not resin, or white glue -- and a little talcum powder mixed in can help smooth out the surface and cover the grain without the associated weight penalty. But to completely coat the body and fins of a model with resin, even if you sand off most of it, still adds that much extra weight for the motor to overcome, because you still have to paint the model on top of the resin.

I tried a similar technique using water-based polyureathane (Polycrylic). The finish, once my wrist came back to normal after all the sanding it required, was glass-smooth. Sanding resin is no easier -- I also build RC planes, and have used FG with resin, there's no significant difference in the work required... :(

Was it worth the trouble? Don't know -- I haven't finished sanding the rest of the body or the booster yet (Estes Astron Omega clone). Only managed to finish the payload body before my wrist complained...

I think just taking more time building the model, using lightweight fillers and surfacing compounds like Elmer's Fill-N-Finish, then priming and spraying with good-quality paints, does as good a job without the excess work or weight. If you're building a catalog model which will never see a motor or go into the air, it might be worth the effort. Maybe. But for a flying model rocket, weight is a killer.

Craig McGraw

I couldn't disagree more. Since I don't have the data, though, the next set I do I will perform a before and after measurement.

Besides which, putting the ultralight stuff on thinner balsa yields a stronger, lighter fin than using thicker balsa. Plus it reinforces the basla across the grain, preventing split fins.



Well, that's overkill (obviously) on an Alpha. An "E" powered ship is a different story.



Reread my post. You stick the stuff on with thin cya and then "fill" the weave with epoxy. However, it is vital that you blot the excess epoxy from the fin - or as you stated - the weight goes way up. In addition, the blotting precludes post-cure sanding. I've also used this method to reinforce a Coupe d'Hiver (rubber powered FF ship, 10g rubber) prop blade set.

Dope isn't the same as epoxy.



I agree that weight is a killer. However, if you're smart about it, you can build a stronger fin using thinner balsa, and get something that is lighter than a thicker "equivalent."

Like I said, the next set I'll weigh them and get you some data. Hell, I'll throw in a load test for free and we can discuss the results.