The tubes should parallel with the bottom longeron of the fuselage and parallel with each other.
To save some time, I purchased the pre-made seat frames and attachment hardware from Avipro.
The front seat slide rails are attached to a couple of 3/4" x .049" 4130N
steel tubes that are welded in between the cross tubes between stations "C"
and "D" of the bottom fuselage frame as shown here. For now I just
tack welded these tubes in place until I am certain everything is fitting
correctly::
The tubes should parallel with the bottom longeron of the fuselage and
parallel with each other.
Next, the seat slide rails were inserted into the seat bottom mount and taped
into position at about the mid-way point of the slide. They were taped
into position with the steel plates parallel with each other but perpendicular
to the seat bottom:
The seat was carefully positioned with the seat rails sitting center on top
of the tubes on the fuselage.
With everything centered, the front seat slide retaining clips were positioned
between the top tube of station "C/S" and slipped over the seat slide plates.
They were then tack welded in place to prevent movement:
The seat slide rails were then tack welded at the front and rear corners:
Now, with everything just tack welded for now, the seat was checked to make certain it would slide forward and back without binding.
Once, everything looked right, the seat slide rails and mounting tubes were
finish welded. They were welded full length on the outside and a couple
of 1" long beads were run on the inside of each seat rail:
To make adjustment possible, a series of 3/16" holes were drilled at 1"
intervals:
For, now I'm just using a 3/16" bolt but will later replace it with a 3/16"
clevis pin with a pull ring.
Here is the completed front seat
installation:
