Rear seat position

[kconner]

I finished building both seats and they turned out pretty good. I read previous posts about cracks when using 2024 T3 so I used .050 5052 half hard and it worked great. When the rear seat is placed on the crossbar support as per the drawings it will not reach the cross member where it attaches at the top of the seat. I am aware that drawings were revised in the past and the cross member at the top of the rear seat was moved aft so the seat could be reclined. It can not be reclined and the top be secured to the cross member without the seat bottom getting into the torque tube and upper elevator control cable. If you move the seat aft it interferes with the upper pulley on the end of the torque tube. CRAP! My choices were to build a rear seat with the seat back angled more rearward or redesign the seat support and use the seat which was built per drawings. Any one else have this problem? I'm sure I'm not the first. I ended cutting out the rear seat support and building new structure and use the seat I'd already built.

Kevin Conner

[Jackal]

In building my seats I did find that they did not work out per the geometry shown in the top left of page 21, and also that the geometry for the two seats was different, one from the other. I also found the 2024-T3 to crack. I ended up using the bottom and backs (the flat pieces that were left over when all of the bends fractured in two) and then made the side pieces again from 5052-H32 and bade the bends on those pieces, overlapped the bottom and back "panels" and riveted them along those edges. Also, instead of making the side piece of the bottom and back attached together (and to the seat back) as shown per plans I made them separate so I ended up having a back panel, a bottom panel, a left and right bottom side and a left and right seat back side as well as the "lip" piece that goes across the front of the bottom, and small strip that was bent and went along the back where the seat bottom and seat back came together, to attach them there. It sounds like a lot more complex, but it really worked well, but did take more rivets, actually looks more "aircraftish" though I think. By making the side pieces as separate pieces you can adjust the "recline angle" built into the seat. The side pieces overlap and I riveted them in that overlap area with the seats "installed" in the airframe. (Note the seat bottom assembly must be slightly wider (or narrower) than the seat back assembly so one can fit inside of the other at the overlap). Its really surprising how much changing that angle changes where the seats contact the cross tubes they attach to. The recline angle of the pilot is set not so much by the "recline angle" built into the seat but by how far forward you pull the seat bottom along the cross tube that it attaches to. Of course moving this requires the recline angle built into the seat to change somewhat, that is why it is so handy to by able to adjust that in the airframe and then set it (by drilling and riveting) after it all works out.

I actually built a set of crude plywood mockups to sort out what was most comfortable for me before building the aluminum seats.

For what its worth, what I ended up with was: (As far as I can tell my fuse was built exactly per plans)

Front seat was 14 1/2" (wider made it hard to get my feet around) wide and aft seat 16 1/2"
Fwd seat recline angle (built into seat) was 10.5 degrees and aft seat 16 degrees
The mounting crossbar for the seat bottom on the fwd seat crossed the seat 10" fwd of the back of the seat bottom and on the aft seat the mounting crossbar crossed the seat bottom 13 3/8" fwd of the rear of the seat bottom.

Don't drill the mounting holes until seats are placed in fuse.

The above geometry will define where the seat back falls on the back mounting crossbar and also the pilots actual recline angle. That was what I found most comfortable for me and it does not interfere with the torque tube assembly (at least it did not with mine (but close) which was also per plan.