Regards the IMPACT thread. A friend of mine recently built the IMPACT (without instructions since there were none at the time), and installed the adjustable stabilizer in his. On the maiden flight, the whole tail of the model nearly came off due to flutter. The whole stabilizer fluttered, and cracked the fuse circumferentially around the front of the fin. He throttled back and made it back safely but the damage to the fuse was quite severe. However the wings, stabs and rudder are all serviceable

I looked inside the broken fuse and saw that there was no reinforcement around the tail anywhere. He was lucky the whole tail did not come off in flight. A warning to everyone who will build an adjustable stab version of this plane. Fuse needs reinforcement in the aft end. I understand that there are factory instructions on-line now, and the aft reinforcement is spelled out. You should heed the warning and build it strong in the tail.

After considerable arguing with the factory reps, he just got a replacement fuse and he asked me to build the adjustable stab for him. I have just completed installation of the adjustable stab in the new fuse. It requires a tail post support block exactly 33.5 mm tall, under the tail post. The tail post was made vertical by using a 1/32" shim on the left side of front engine/chin cowl area.

The stab aligns at zero degrees with this 33.5 mm support block in place, and the front engine area supported as explained above. The bottom of the fuse must be in contact with the flat bench. I run my height gauge scriber along the fuse sides in the back, scribing the stab center lines, both sides. Table surface is plate glass and facilitates height gauge movement. Very light scratching was done to the fuse sides with the carbide scribe, and then the scratch was penciled in for visbility. Very thin, about the tickness of a human hair.

Inside the fuse, I supported the tail with a bulkhead in front of the fin, and a horizontal balsa brace from the bulkhead to the tail post. It was fitted to touch both fuse sides all the way to the tail post and to slightly bulge the fuse sides out to fit the stab perfectly. The carbon stab tube and 1/8" adjuster rod are epoxied to the brace.

The stab roots needed a little sanding to get proper triangulation. I am happy with the installation result.

BTW- the way I align the tail post center line with the stab centerline is through the use of a large 30" plexiglas isosceles triangle I made a long time ago specifically for this critical alignment. The triangle "height" is scribed in and is perpendicular to the large side or base. A series of parallel lines to the base are scribed onto the plastic with the back of a x-acto knife, and all scribed lines are penciled in. It makes perpendicular alignments a cinch and takes all the guesswork out.

The wing will be installed later. Wing alignment is easy once the stab and fin are aligned. Hope this helps some of you putting the IMPACT or any other model together

Matt Kebabjian