Brief Description: Cutting hull for mounting airframe
OK... this Step 12 of Section 5 is really challenging. You have to visualize what is happening in three dimensions, get the geometry into your head, then roll the tape. The boom tube is pinned back at the transom so the front of the airframe is rotating down off that centre point. This means that the bulkhead tube will shift backwards from its initial position sitting on the lip of the hull. I suppose because every FRP hull is slightly different PA doesn't give exact dimensions for the hull cutouts for this in the manual. I found that the aft sides of my bulkhead tubes were 1.5" forward horizontally from the upswing in the hull lip when the tube was sitting on the top of the lip. I drew the lines down from the tube as described in step 12. Then, forwarned by other build loggers and "Nelson" Glen, I marked my cuts back 1/4" and went at it with the Dremel. But I still had to trim the back edge repeatedly to get the whole frame to sit onto the hull stringers as it should. My final position suggests that I should have cut the forward vertical line at 3/8" back from the front edge starting line (and down 2.5") and the aft vertical line at 2.5" from the aft edge starting line (and down 2 5/8"). I didn't need the spacer blocks mentioned in step 13.3. I tried using putty as described in step 14.1 but this turned out to be a messy waste of time. Drilling the 1/4" holes to secure the frame to the hull stringers per steps 14.2 and 14.4 was a bit problematic but I managed with a standard drill. An angle drill would have been a great help, but that is another tool for another day. I shudder to think of how I will get the nuts onto the forward bolts later in the build. Many build loggers describe installing aluminium plates along the hull stringers at the bolt locations to somehow absorb impact load from the hull to the frame. To me this sounds like a difficult and useless complication as the plates, metal or otherwise, will just serve as spacers. So I will use the spacers provided. Step 16.3 is clearly wron
