fuselage cross members and tailpiece

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jeffreyK
Posts: 43
Joined: Wed Jan 15, 2020 9:41 pm

fuselage cross members and tailpiece

Post by jeffreyK »

I have finished the sides of the fuselage and now having issues with where to put all the cross members. Looking at Diagram #1 and #4 there are measurements but not for the "long" fuselage. I do notice markings for the wheel crossmembers and the dual control diagram shows where they will be in relation to the vertical spars but all of the others (particularly those aft of the pilot seat) would be at different distances than mentioned. I've found three links on crossmember questions but they don't seem to really answer my question beyond the position of the wheel braces.

Secondly, looking at tapering the tail down to a half inch on both sides for an inch width (at the tail end) epoxied together leaves considerable room for potential slop in the tailpost. I was thinking of possibly cutting out my tailpiece spar and epoxy a new one on after tapering the longerons and spar #14 on each side. If I start with a tailpiece 1"X1-1/4" I can taper it to meet the longerons and be 1" at the end. I'm thinking this way the tailpiece will be solid and I'll have a more solid construct holding the third rudder hinge.

Any feedback appreciated.
Earl Brown
Posts: 69
Joined: Mon Nov 04, 2019 12:24 pm

Re: fuselage cross members and tailpiece

Post by Earl Brown »

The crossmembers go across the fuselage where the vertical side member junctions are, just like they do on the "short" fuselage.
DSC_0150.jpg
I left the tailpost off until the sides were glued together, then glued in a solid piece of wood and shaped it to the fuselage sides.
mdwray
Posts: 3
Joined: Sat Jan 14, 2023 6:42 pm

Re: fuselage cross members and tailpiece

Post by mdwray »

What are members opinions on the alternative ways of installing the tail post - add a tail post to both fuselage sides, chamfer down to 1/2 ", glue together at same time longerons are glued together OR glue longerons together and add one piece/solid tail post.?
jeffreyK
Posts: 43
Joined: Wed Jan 15, 2020 9:41 pm

Re: fuselage cross members and tailpiece

Post by jeffreyK »

I believe different builders took different approaches to this issue. I took a lot of time, made a jig to guide the saw and used a Ryoba razorsaw to make the scarf joints. This epoxied together nicely with a large glued surface. Because it tapers there are two new issues. A filler strip is needed to have a flat surface at the tail for the third rudder hinge. This of course has to be in line with the aft end of the vertical stabilizer so all the hinges line up. The second issue I faced was the brackets above and below the horizontal stabilizer won't lineup. I made angled shims which I epoxied in place where these brackets bolt to the fuselage. It worked out nicely for me. Now they line up above and below the horizontal stabilizer. I'm sure there are others who found other ways of reaching a workable solution.
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