Sunday, October 10, 2021

Fabricating and fitting the F-712D elevator stop - 4 hours

Looking around for the angle material for the F-712D and I just cant find AA6-125X1X1 1/4. However I have the same thickness material in a larger size. AA6-125X1 1/2X2 (Something like that) which was scrap from an early part of the fuselage build.  The angle will work just great as I can cut it down. The inside radius is a bit thicker, so in order to make it work I just need to increase the dimensions very slightly. 

I did a rough cut of the angle with exaggerated dimensions.  I will trim it down after I have drilled the mounting holes.

After marking and measuring everything. It was time to start drilling #40 pilot holes. 

Next I started opening up the holes for AN3 bolts. Stepping each one up #40 to #30, to #21 (Which allows a #8 screw for perfect alignment and "clecoing") and finally reamed to 3/16"


 Now its time to set the 1/4" offset on the vertical stab. Using lines I had previously drawn when setting the horizontal stabilizer. I can easily set the offset. But I just was hit with a huge crap. When trimming the VS-702 I set the proper height according to a straight VS. However...those measurements change when you begin the offset. I had good edge distance on the  F-781Vert. Stab attach plate, but as soon as I moved the 1/4" offset....nope. 

I dug out some 0.063" material that I have and cut out a new F-781Vert. Stab attach plate. I then moved all the rivet holes up about 3/16". Bent the plate between two pieces of oak and bingo bango. Done. 


 The drilling of the attach plate to the VS-702 is fairly easy after this. The front of the VS is aligned with the 1/4" left offset. A straight edge held to the hinges at the VS rear spar to set the proper height of the front of the VS. Clamp it all down and drill with the 90deg pneumatic drill.  

After that's done, I removed everything allowing good access to use a drill jig and upsize the attach plate/HS mounting holes to 3/16"


 In case you are wondering....I use a ton of washers during preliminary assembly so I don't use/abuse the nylon locknuts. I want to reuse the nuts for final installation and I feel much better about it when I know the nylon is "new and untouched"