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I have replaced the original Kolb supplied gap seal. I used the original as a pattern and made the new one from unsealed light weight red Dacron. Because the fabric is not sealed, it has a tendency for the leading and trailing edges to vibrate or buzz during flight.
The trailing edge was easily constrained by sewing some Velcro to the middle of the trailing edge. A longer mating piece of Velcro was glued on the top of the motor mount support tube. This lets one stretch the trailing edge to the rear and fix it to the tube, and it eliminates trailing edge flutter. |
At cruise the air passing over and around the pilot's head helps cause leading edge to flutter with a very annoying buzzing sound. While fabricating the new gap seal, a large buttonhole was placed in the front hem next to the Velcro. A 17.5-inch long 5/16-inch OD tube was inserted through the buttonhole into the hem.
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To keep the tube from slipping out of place, a safety pin was passed through the fabric and on through a hole drilled sideways through the tube. The tube stops all the buzz from over the pilot's head.
While cruising at 5,200 rpm, sound level at the top of the stick was 105 db. This as good as the FireFly was after carving "Power Tips" on a three blade propeller. Currently the FireFly is running a two blade propeller without "Power Tips". |