By Bill Evans, EAA Chapter 266, EAA 794228
I went for a speed flight a few weeks ago, just to see what sort of top speed I might get at full throttle. I got, say, 160 mph at 3200 rpm. It has run faster, but only if I lower the nose just a tad to get to 180 before leveling off at 3300 rpm. I’ve changed facet fuel pump models more than once in an attempt to get the power I expect from the upgrade to a more powerful engine.
I was thinking more about CHT 275 F and EGT 1375 F than fabric, but I did notice a flicker of a fabric tape and heard the tiniest flick on the left side. Surely a tape is nothing.
When I climbed out of the cockpit after landing, I then saw the left side of the fuselage looking nasty, with bits of tape streaming back. I cut off the streamers and put the aircraft away.
The fall weather has given warning that it will turn here if it has not already. Whatever is to be done, the wings needed to come off first. Thus, my friend Steven Craig and I went out to Lancaster just to pull the wings off. Jim Aylesworth and his friend Bob were circling above in his Stinson 108. Jim re-covered his Stinson a year or two back. It looks good, and I believe he used the Stewart system.
After landing, Steven had the taper pins pulled out, so the four of us lifted and hung the wings, each weighing 37 pounds. As an aside I asked Jim how long it took him to strip fabric from his Stinson. It was 1345. He replied that we had 15 minutes and should start. We brought out the short knives and by 1400 had 80 percent of the old fabric off the Sonerai and in the garbage. Jim and Bob left then, but Steven and I continued, and by 1430 had about 99 percent of the fabric off. Some strips are riveted on, and the rivets needed drilling. I saw slight surface rust on the tubes for the stabilizers. They are painted with zinc oxide. After prepping the fuselage for re-covering, eight days were used to re-cover the fuselage. The elevators and stabilizers not included will follow shortly. Fuselage top tapes were glued and bonded on day nine.
The Stewart system is nice to use because none of the chemicals are toxic. You can use them day in and day out, and your skin and lungs are not adversely affected. I wear gloves anyway, but Gord, my buddy on the project, usually doesn’t.
The blue stuff you see pictured is EkoBond, which is a water-based glue costing about $100 per liter. Water is used for cleanup. A brush can be made to last for a week or more.
On inner tubes and areas where the fabric touches, I apply cloth tape with adhesive on one side. The fabric can slide over the tapes a little during shrinking. Sixty yards costs about $15. On the tail surfaces, the taped areas are held in place with lacing. I use a modified seine knot tied the way EAA teaches it. I use the flat lacing from Aircraft Spruce. It is very thin but will not break in your hands, and it costs about $60 a spool. There is really no acceptable alternative.
The process is to wipe the tubes with acetone to remove old glue residue and then paint the glue onto the edge tubes, over which the fabric is to be folded. It may take 30-45 minutes for the glue to become tacky enough for the fabric to stick. If it’s not straight it can be pulled off and reapplied, which is nice. Once in place, a small iron set to about 2 is used to bond the glue to the fabric. Where possible, the fabric is stuck to three sides of tubes. It takes some time for the glue to set enough for shrinking. Usually I wait until the next day. I use a household iron calibrated to 2.3 to get 250 degrees Fahrenheit, which is the temp I use for the first shrinking. The fabric shrinks slowly, but the iron never stops moving anyway. It may take five or six passes before the fabric is a bit taut.
Adjacent fabric panels are overlapped about 2 inches. Once again, glue is applied to the first panel and allowed to dry before ironing the adjacent panel in place. In addition 2- to 4-inch-wide tapes are used to cover the panel joints. I also put a tape down the centerline of the belly panel. Tapes can be bought from Spruce, but they can also be cut with pinking shears from leftover fabric. I bought Wiss pinking shears online for $12. In my humble opinion, there are none better.
Fabric replacement requires patience and planning. Often, new areas can have glue applied in preparation for applying fabric, but not always.
In the turtledeck area, I glued the fabric to the forward or flat face, then used the small iron to shrink the curved section to lie flat on top of the turtledeck. It takes maybe five minutes to shrink it in this way. Once it lies flat, glue is applied to the fuselage under the fabric. When tacky, it can be bonded to the turtledeck. Done carefully, the result is very nice.
Anytime glue residue builds up on the fabric, a gum eraser can be used to remove the dried glue. It works well if you use it carefully.
We did nearly all of the fabric panel edge tapes. Bottom of left side is the last one to do. The aft panel gives access to connect the horizontal stabilizer and connect the electric stab trim actuator to the stab.
