Shanksow, On that thrust tube, I just curved a plastic sheet to fit into the back of the plane, and pushed it in till it reached the fan unit, and while holding it in place I dropped c.a. in around where it touched the fan to hold it in place. I trimmed the back in to shape of the rear of the plane and dropped c.a. around the edges to hold it in place. The plastic dose not reach around to the top of the fuse. to make it a simple installation. I put the cone on the end to drop the exit down from 3in. to 21/2in. and c.a. it into place. My first thrust tube was made out of balsa and c.a. thin wicked down into it. It took 5 min to make and install this.