CL Aerobatics
fiberglass cloth. The ends can be reinforced with thin plywood or aluminum rings.
Ben Cleveland, Leesburg FL, recently described the method he uses to build P-30 fuselages. His version offers a couple of clever ideas. Following is his method.
Use 1/32 sheet balsa, brushing on a single coat of dope on one side. After the dope dries, soak in water and roll around a form. (Aluminum tubing works better than a dowel. Bind with an elastic bandage, but don’t pull it too tight.) After the balsa dries, remove from the form and glue the seam. Sand smooth.
For extra strength, Ben adds 1/8-inch-wide strips of 2.9-ounce fiberglass cloth at the front and at the motor peg location. (As with many P-30 fliers, Ben uses a full-length motor.) He also adds two 1/8-inch-wide strips at the pylon location. The carbon cloth is applied with epoxy laminating resin, blotted with a paper towel to remove excess epoxy and reduce weight.
After the epoxy hardens, Ben covers the tube with lightweight Oracover transparent polyester film. This is an adhesive-coated, iron-on material available in yellow, blue, orange, and two shades of red. You can order it from Hobby Lobby, 5614 Franklin Pike Cir. Brentwood TN 37027, or www.hobbylobby.com.
Unlike tissue and some other plastic films, Ben feels that the Oracover adds significantly to the strength. “It pre-loads the tube,” he said. “It’s amazingly stiff and strong. Since no dope or other finish is required, the weight can be low and predictable. I’m coming out lighter than with Micafilm,” he added.
On the subject of tubes, Thurman Bowers, New Smyrna Beach FL, offers yet another variation. Instead of doping the balsa sheet before wetting and rolling, he coats the inside of the tube after rolling. This makes the rolling operation easier and reduces chances of the balsa splitting.
“I use dope in the tubes much like cleaning a rifle,” said Thurman.
He pours a small quantity of full-strength dope in the tube, then takes a household sponge and cuts a rough ball that requires slight compression to fit in the tube. He uses a length of 1/4-inch dowel to shore the sponge, which quickly becomes saturated with dope, back and forth a few times, adding dope at either end as required.
After the dope dries, he sands the inside of the tube using synthetic steel-wool pads. These resemble a kitchen scrubbing pad but have abrasive grains bonded to synthetic fibers. Their main use is in furniture stripping and refinishing with water-soluble products. The brand he found at the local home center is All-Gator Grit by All. A package of a dozen 2-x-4-inch pads is approximately $4.
“To use the 400 (fine) grit which I guess to be the equivalent of 220-grit sandpaper,” said Thurman, “I just crumple a piece of the pad into a ball, compress it enough to fit in the tube, and run it back and forth with a dowel. Since all surfaces and fibers are coated with abrasive and the ball is a tightly fit, it does a great job of sanding the doped surface inside the tube. My most recent tubes were put through this process twice, which seemed to stiffen them considerably and serves as a barrier to tube and moisture.”
Transcribed from original scans by AI. Minor OCR errors may remain.
