I think the decision of what kind of seat is  every bit as important a decision 
as to what resin or wood we use in our airplanes. I would say that there is 
little argument as to the simplicity of the stock sling seat but if you are 
going beyond that then it should require some real thought especially when you 
consider the possibility of having a real bad day and then that seat may be the 
only thing between you and concrete.

I have resized and attached a photo of my two seat designs that I came up with. 
The first one is the grey composite seat. Made by just cutting and fitting foam 
between the spars all the way down to the bottom of the fuselage with cutouts 
for the cross members of the fuselage floor so the entire seat bears on the 
spars and bottom skin. Since it is solid foam I liked the idea that should I 
have that bad day the glass would probably fail pretty quickly but the foam 
would continue to absorb a load assuming it stays in place. I am 6'-5" and I 
have already deepened my fuselage to get the required headroom that I am going 
to need while wearing a headset . Even by doing this I had to cut down the 
depth of the seat as much as possible to get my butt as close to the bottom as 
I could. By doing this I effectively destroyed the ability of my seat to take 
any real load. As it loads up it will "form" itself to the available area 
between and over the spars. As the load increases the bottom of the fuselage is 
going to flex and the only thing that will hold the seat is the spars. Each 
side of the seat becomes a shear web at this point but because of the depth of 
the seat its load carrying ability is zilch almost regardless of how thick I 
make them. And since most of the load of my reclined body will be on the aft 
portion of the seat this is even worse.

Now look at the aluminum version and remember this is really all because of my 
height. By using a 1/8" sheet on the bottom I can get my butt as close as I 
want it to be to the bottom of the fuselage. I then used the same thickness of 
sheet to make 2" deep sheer webs on each side of the seat. These span the full 
length from spar cap to spar cap and then over the edges of both. The bottom 
has an "H" pattern of 1" x 1" x 1/8" angles that span from sheer web to sheer 
web and the cutout for the stick is lined in the same material. Also by bending 
the aft part of the seat from the bottom slope to the horizontal I create 
additional stiffness. The back of the seat is the same back as used on the 
composite seat and is hinged for access behind them. Believe it or not there is 
not much if any difference in weight between the two once the lightening holes 
are cut. Both versions use the same cushions so it is fairly comfortable but 
the load carrying capabilities are miles apart.

And if you think this welding is bad you should have seen the intake manifold 
on the old Subaru, downright breathtaking.

Stephen Teate
Paradise, Texas

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