Bede BD-4C Custom Front Seat Support

If you have been following my progress building my Bede BD-4C airplane for long, you may have wondered if I quit or vanished or what. I have not posted an update on the project in almost four months. No, I did not quit but I did have a death in my family which kept me from working on my plane for a long time. Even now, I have less free time than I did, due to the fallout from that event.

Over the last few weeks, I have gotten to work on a few pieces of the plane. The front seat support is finally done, as are the bases of the front seats. All of those pieces back from the welder. I also have the shoulder belt attachment for the rear seats back from the welder.

Here is the front seat support in the Bede BD-4C. I have set tracks on the pilot’s side and set the base of the pilot’s seat on top of the tracks. In this photo, the tracks are extra long because I have not yet cut them to length. (You can click this photo, or any other, to see a larger version.)

Here is a close-up of the tracks, cut to length. You can see the holes drilled into the support. I will rivet the tracks to the support using cherry rivets, which are strong enough for an application such as this.

The front ends of the tracks have a pair of holes where a “stop” can be attached, to keep the seats from sliding off the front of the tracks. Since I cut the tracks short, I had to drill and tap new holes in the back ends of the tracks.

This was new to me; I had never used a tap before. This hole is for an 8×32 bolt and the tap calls for using a #29 drill bit. I was dismayed to find that my drill set included two #30 bits and no #29 bit. Since the #30 is just a measly .0075 inches smaller, I thought it might work anyway. Wrong! Fortunately, I tested in a scrap piece of seat track because I broke the tap trying to cut the threads in the too-small hole. I trip to Menards and four bucks scored me a replacement 8×32 tap with a #29 drill bit. The right tools made short work of making the holes.

The main part of the seat support rests on top of the landing gear box, the piece of structure to which the main landing gear is attached. The front of the seat support slides into a pair of brackets that are attached to the fuselage walls. Here is the bracket on the pilot’s side, sitting just above the pulley for the aileron cable.

On a couple of off-evenings, when I was waiting for the welder to finish up the steel parts pictured above, I started working on the floorboards. Lots of people use 3/4 inch aluminum honeycomb because it is light and strong. I am using 3/4 plywood because a) the original BD-4C plans call for plywood, and b) I had some sitting my garage. I might swap it out for aluminum honeycomb sometime in the future.

Making floorboards gave me an excuse to mount my dado blade on my table saw. That’s a cool blade that I don’t get to use very often and it was perfect for cutting grooves in the bottoms of the floorboards. There are rivets sticking up through the fuselage skin. The grooves allow the floorboards to sit flat on the skin, instead of having all of the weight on the heads of the rivets.

Here is the bottom of a piece of the floor, with the grooves, and a shot of two of the boards in place in the plane.

I stole one other evening to install a vinyl tube through the fuselage, from just behind the baggage compartment all the way to the tail. It is held in place with adel clamps and has a pull-string through it. Should I ever need to run an electrical wire to the tail, now I have the means to do it.

Here is the back of the tube, with the aviation-grade kitchen twine cable-tied in place.

My safety harnesses (seat belt + shoulder belt combination) arrived today. I will post pictures of those, along with the attachments, soon.