Design by: James Huber
From: BD-4 Newsletter 21, Sept., 1993, text by Roger Mellema
In the last newsletter, I talked about the clever, individually adjustable, for all sized humans, sort of light weight seats that Jim Huber designed. The nice thing about these seats is that they not only move a reasonable amount fore and aft, but they also change height and seat angle. They are designed to accommodate the Air Force standard "large and small" human. Jim is using the basic seat from another airplane and just added all of the lower structure. In the upper figure note that the lower seat position is shown in lighter lines and I did not show the telescoping adjuster tube. The lower figures show the front and rear support tubes as viewed from the rear. All tubing sizes and some approamate lengths are shown to get you started. Changes can be made to fit the spare 4130 you might have lying around and also to better fit your physique.
The two 4130 tubes (0.875" and 1.5") that the seat "posts" rotate about go all the way across the cabin. The seats adjust independently but must be adjusted while on the ground. A screw jack arrangement could be fitted for adjustment while flying.
All steel parts are 4130. Flat pieces are 0.125" thick. Hardware is all AN-4. The most difficult part of fabrication is welding the end of the 0.5" pieces to the larger tubes. The welding distorts the tubes and causes slag to form on the inside. This slag has to be removed so that the tube will slide over the large tubes that reach across the cockpit. If you want to lubricate (motion is negligible), do it with something that is waxy. You don't want it getting over upholstery and clothes.
Below is the second page from the newsletter article with
the drawing. Click here to see a larger scale copy of
the drawings (you'll need Adobe's PDF Reader 
).
Ed.: This modification will only work with the taildragger configuration!
Click on the pictures to see a larger image.
Here are two pictures from Jim's setup. The second picture is just a detail view of the first.
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Click on the pictures to see a larger image.