- This topic has 12 replies, 7 voices, and was last updated 15 years, 11 months ago by
.
-
Posts
-
What is the best way to make a rolled balsa tube for the fuselage?
😕This is the edited version.
Use a straight form. I recommend conduit pipe. I use a piece of 7/8″ for P30 fuselages.
Select a sheet of light straight (A) grained balsa and apply two coats of nitrate dope on ONE SIDE ONLY!!! The sheet will start to curl.
Cover the doped side with tissue with the grain of the tissue running lengthwise. Allow to dry 24 hours.
Now, bring a pot (teapot with a spout preferred) to boil.
Place the fuselage blank in the bathtub, and pour boiling water on it. It will now curl into a tube practically on it’s own.
Place the blank on the form and secure with gauze, Ace Bandage or other soft but wide device. Allow to dry at least 24 hours. I take mine up into the attic to gain a bit more drying from the heat.
Take off the gauze, bandage, whatever.
With a single-edge razor blade, cut carefully through the overlap so as to create a butt joint for the seam.
Now, carefully slide the blank off the form and hit it with CA every few inches. Watch that you don’t allow the CA to seep down the joint and bond the blank to the form.
Once the blank is off the form and the entire seam is sealed with CA, slide it back on the form and cover the outside with tissue. This time, cut the tissue into 2 inch wide strips and wind the tissue around the blank on a 45 degree angle with the long axis of the tube. You want a bit of overlap of the tissue wraps.
Allow to dry overnight and you have a nice, light, and rigid tube.
Cut to length, add reinforcing, hardware and wing/stab/fin mounts and enjoy. 🙂
I use the same method except I scarf splice the seam. Sand one edge of the sheet to a taper, going in about 1/4 of an inch in. This leaves one edge looking like a wedge. Wrap the mandrel, or form with wax paper. When you get the wood out of the tub, apply white glue on the wedge . Wrap with an Ace bandage as you roll the wood around the mandrel. When dry, sand the top part of the sheet to match the tube.
This joint seems a little stronger than a butt-type.I agree with Dean and I scarf the joint like Bill. For a P-30 form I use copper water pipe.
When possible, I prefer a “B” grain wood, it results in a stiffer tube – not so squishy. To check the wood, cut an inch or so off the end of the sheet, soak it in water and wrap around the form. If it cracks, you need to lean toward more “A” grain.
When using the Ace bandage, don’t wrap it too tight or the fabric will imprint on the wood.
As I take the bandage off, I replace it with a few rubber bands to keep the shape while on the form. Like Dean does, slide it off the form and glue a section at a time. Keep rolling the rubber bands back on the form to keep the shape.
I place the lapped seam on the bottom because it’s a little stronger. Also if it warps, it will probably be up and down rather than to the side. No bananas, please!
– Norm
Not to worry about wrapping tight and getting imprint on wood – After it is dry and you’ve glued it, simply run a wet finger over the entire surface and watch the imprint disappear as the compressed wood is relaxed. This is an old woodworkers trick for dents, etc… even on hardwoods prior to finishing – and sure enough it really works well on balsa. Whatever you do, don’t try to sand out the imprint – you’ll lose almost 1/3 the thickness of a 1/32nd sheet tube.
i just thought i’d pass along a neat tip i learned from an old time modeler and friend.
he got me re-forming balsa, and any other wood by soaking with amonia, and putting the wood on, or in the shape you want and let dry. he explained the amonia breaks down the celulose, and then as it evaporates, the celulose “glues” the fibers back together again, with the fibers being in the new configuration. i’ve been using this for about thirty years now and never had any warps occur later on….. even put a permanate curve in a two by six pressure treated board for the deck out frontusing amonia.. just have to be real careful about inhaling!!
anyway, i’m new to the forum and just wanted to say “howdy”!! 😀
billHey Titusville,
Are you coming to the meet this weekend at Palm Bay?
Reply to my email: flydean@worldnet.att.net
hey dean, didn’t know there was one this weekend. haven’t talked to brian in a long time. did you ever meet Brian Malin? i’m finanlly getting a bunch of issues cleared up and can get back to building and flying again….
i haven’t been there in a while either, have to find my way back!!
thanks, bill
hey dan, i apologize if i borrowed your signature……i didn’t read many posts before i registered…..
i’ll fix it, thanks, bill
Bill, i don’t see that you’ve snagged my signature. Dean is the guy who explained about the importance of caps for Free Flight.
thanks dan….
hey dean, i’ve known brian for about 16 years now. he’s really great people!! he was one of the founding members of our club here at Kennedy Space Center. i’ve built a couple of his kits, and still have the .020 size “Timer’s Nightmare”, i built from his prototype plans years ago…..
we have aquired a new field, or piece of ground, from the Kennedy recreation organization and when some of the work there is complete, we’ll have room for some limited Free Flight…….short D/T’s will have to be used…..haha
thanks, bill
- You must be logged in to reply to this topic.