Third time charm

[Andy Walker]

I have not been happy with my spar tunnel build, and have basically built and re-built it three times now. I finished up the version 3.0 build on Monday (only dimpling remains to be done), and I think finally I'm happy with it. Maybe I was being too paranoid about it, but I really want the part where the wings attach to be as well done as possible... :lol:

Anyway, I have a few tasks left to do, then I can rivet and make the horrors of plans page SNX-F11 a dim memory... 8-)

[142YX]

what were your errors that prevented you from sticking with version 1 and 2 if you dont mind me asking?

I have also made several parts two or three times.

[Andy Walker]

The first one was probably actually okay, but I didn't like the large size of my sheet metal holes after dimpling, so I decided to re-make the fore and aft sheet metal, and the holes mating the forward tunnel to the top aft angle were too close to the edge, and I worried about strength (Kerry at Sonex agreed). In the process of mating the existing parts to the new parts, some holes in the thicker parts got enlarged, and I decided to re-make them. Then I realized I had some significantly out of round countersinks on one of my rear wing attach angles, which would have compromised the strength of the rivet joints. SO I decided to re-make that angle, but if you look at the plans you'll see that angle attaches to a LOT of stuff (side skin, aft tunnel skin, shear plate, and three different gussets), so it was a very long and slow process getting that angle properly drilled to where it would mate with all those parts keeping the geometry correct and not enlarging any holes.

In the end, I'm very happy with my result, it just took a while to get there... :roll:

[142YX]

one of my "i hate the way this came out, but i am going to live with it" parts was the sparbox sheet. I am not quite sure where the error originated, but my entire forward fuselage floor skin is about 1/8" too far back from where it should be. It probably occurred way back when i was building the aft fuselage and positioning that floor skin. This didn't result in being a big deal, except for the spar box. The side to side rivet line along the floor is also too far aft, because that floor skin came pilot hole'd. My rivets just barely clear the forward radius where the spar box meets the floor. If they were just 1/32 or so farther back, it would have been bad news for me.. i believe to the tune of a new floor skin, lower longerons, and sparbox. I slept on that one for a while.. but eventually convinced myself it was ok.

[Andy Walker]

one of my "i hate the way this came out, but i am going to live with it" parts was the sparbox sheet. I am not quite sure where the error originated, but my entire forward fuselage floor skin is about 1/8" too far back from where it should be. It probably occurred way back when i was building the aft fuselage and positioning that floor skin. This didn't result in being a big deal, except for the spar box. The side to side rivet line along the floor is also too far aft, because that floor skin came pilot hole'd. My rivets just barely clear the forward radius where the spar box meets the floor. If they were just 1/32 or so farther back, it would have been bad news for me.. i believe to the tune of a new floor skin, lower longerons, and sparbox. I slept on that one for a while.. but eventually convinced myself it was ok.

Interesting...how's the front look, where the floor skin meets the firewall, lower motor mount brackets, etc? No problems with having not enough skin for your fasteners?

[rizzz]

one of my "i hate the way this came out, but i am going to live with it" parts was the sparbox sheet. I am not quite sure where the error originated, but my entire forward fuselage floor skin is about 1/8" too far back from where it should be. It probably occurred way back when i was building the aft fuselage and positioning that floor skin. This didn't result in being a big deal, except for the spar box. The side to side rivet line along the floor is also too far aft, because that floor skin came pilot hole'd. My rivets just barely clear the forward radius where the spar box meets the floor. If they were just 1/32 or so farther back, it would have been bad news for me.. i believe to the tune of a new floor skin, lower longerons, and sparbox. I slept on that one for a while.. but eventually convinced myself it was ok.

I had a similar experience in the last few weeks but in my case it were only the pilot holes in the floor skin to attach the aft tunnel web assembly that were too far aft (and I mean really too far aft, my holes lined up with the edge of the flange on the aft tunnel web assembly). Strangely enough the forward tunnel Z and all the other holes were perfectly positioned.
It turned out my floor skin was just made incorrectly, those holes were just drilled too far aft.
I just remade the floor skin, this was fairly easy since I could use the old one as a template (but not for that line of pilot holes that was positioned incorrectly off course, I had to reposition those).
All turned out well in the end.
http://www.mykitlog.com/users/display_l ... 1277&row=4
http://www.mykitlog.com/users/display_l ... 1508&row=3
http://www.mykitlog.com/users/display_l ... 1545&row=2

[142YX]

Interesting...how's the front look, where the floor skin meets the firewall, lower motor mount brackets, etc? No problems with having not enough skin for your fasteners?

The front was no issue at all.. didn't even notice there was a problem until i went to install the sparbox. Ill try to grab a picture today when i go to the hangar

[Andy Walker]

Interesting...how's the front look, where the floor skin meets the firewall, lower motor mount brackets, etc? No problems with having not enough skin for your fasteners?

The front was no issue at all.. didn't even notice there was a problem until i went to install the sparbox. Ill try to grab a picture today when i go to the hangar

Cool, glad it all worked out! My issues are hopefully behind me and I can get on to the next mistake. :lol: