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- Apr 7, 2008
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I'm doing a complete rebuild on my AS1. I now have a full set of plans to compare what I have on this plane and what I should have on this plane. I'm not sure why I'm writing this, whether I'm looking for advice or just posting this to see what any of you gurus have to say. The first thing I found that's not to plans is the horizontal stab. mounts. They were built correctly, but for God knows what reason, the builder bent the top longerons down at station 6 so that they go into the tail post 3/4" lower that plans. That put the aft stab. mount 5/8" lower than plans making the forward stab. mount 3/8" higher than the rear instead of 1/4" lower as called for in the plans. I'm told that the forward part of the stab. is designed to be a little lower that the rear spar so to put a little negative pressure on the stab. The guy that flew it back from No. Carolina said after 22 landings and T.O.'s that it was hell to keep the tail down during the mag. checks.
The next thing I found was the center wing section was set 1" off center to the right, which meant the wings were offset also. That's why I have had to rebuild the 'I' struts. With everything offset, the old angles on the the 'I' struts would no way fit back in and in fact were a 1/2" different in height when set side by side.
Setting the wings up to re-weld the 'I's, the first thing I found was although the right wings were perpendicular to the frame, the left upper wing was 1/2" forward and the lower left was 2" aft of square. The distance from each lower wingtip to the tail post was exactly the same which questions how straight the frame was welded up. The guy obviously did not look down the trailing edge of both wings, but just went for the tip to tail measurement. This had to be fixed by elongating the bolt holes so I could shift the top wing back and the lower wing forward, then tig welding the holes back to round. I had cut off the old square tubing on the 'I's and made new, hoping to use the old expensive oval tubes. After setting the lower wing dihedral to 2 deg. and then trying to fit the old cut 'I's to the new square tubes, they were far too short. About an inch too short which meant the builder had to have had over 3 deg. of dihedral. The insidence was also off. 2 degrees instead of 1 1/2. If I wanted to correct this it would mean welding new bracket(s) on the frame so I said the heck with that.
The funny thing about all of this is the plane flew just great. I could hands off while looking at a chart and she would go straight and level. Even the 'I' struts, when I took them off didn't have even one washer under the square tubes. Go figure. Either these little bipes have a lot of latitude for being built bent, or someone got real lucky and canceled out a lot goofs.
Any comments except for "You should have left it alone" are welcome.
Garry
The next thing I found was the center wing section was set 1" off center to the right, which meant the wings were offset also. That's why I have had to rebuild the 'I' struts. With everything offset, the old angles on the the 'I' struts would no way fit back in and in fact were a 1/2" different in height when set side by side.
Setting the wings up to re-weld the 'I's, the first thing I found was although the right wings were perpendicular to the frame, the left upper wing was 1/2" forward and the lower left was 2" aft of square. The distance from each lower wingtip to the tail post was exactly the same which questions how straight the frame was welded up. The guy obviously did not look down the trailing edge of both wings, but just went for the tip to tail measurement. This had to be fixed by elongating the bolt holes so I could shift the top wing back and the lower wing forward, then tig welding the holes back to round. I had cut off the old square tubing on the 'I's and made new, hoping to use the old expensive oval tubes. After setting the lower wing dihedral to 2 deg. and then trying to fit the old cut 'I's to the new square tubes, they were far too short. About an inch too short which meant the builder had to have had over 3 deg. of dihedral. The insidence was also off. 2 degrees instead of 1 1/2. If I wanted to correct this it would mean welding new bracket(s) on the frame so I said the heck with that.
The funny thing about all of this is the plane flew just great. I could hands off while looking at a chart and she would go straight and level. Even the 'I' struts, when I took them off didn't have even one washer under the square tubes. Go figure. Either these little bipes have a lot of latitude for being built bent, or someone got real lucky and canceled out a lot goofs.
Any comments except for "You should have left it alone" are welcome.
Garry
