Bede BD-4C Construction: Day 1

I spent the day at Bede Corp, helping construct the wings of my Bede BD-4C. For a complete newbie like me, it was quite the experience and I sure learned a lot. For instance, assembling the wings is pretty straightforward if you have done it before and have all of the jigs, clamps, and tools readily at hand. I cannot imagine how much longer it would have taken to do at home what I accomplished in less than a day with Rob’s help and Bede’s jigs.

This will almost certainly be my longest construction blog posting. As I get further into the project, I will be spending as much time as possible actually constructing the plane and much less time documenting the process. I’m sorry, Gentle Ready, but better I should be honest with you now that disappoint you later.

Rob and Steve, both on Bede’s staff, were hugely patient with me as I struggled to understand the project and to do as I was told. By the end of the day, with Rob’s help, I had two wings moving along nicely toward something that I would be willing to trust my life to. And, with Steve’s help, I am gaining a better understanding of how the pieces should actually be assembled to create a flying airplane.

Rob started me out replacing Clecoes with pop rivets to permanently fasten the rear spar to the back of the ribs of the right wing. I got my first object lesson in the joys of pneumatic tools. This job was a breeze with the aid of compressed air. When I was done, the wing looked like this.

I then moved on to enlarging the holes in the ribs for the left wing so that they would fit onto the main spar. Apparently, the inner walls of the tubular spar are precisely dimensioned but the wall thickness is not precise so the outer shape is not a perfect cicle. Since the ribs are precisely cut on a CNC machine, the holes need to be tweaked slightly.

Unfortunately, I did not get the hole large enough on rib #9, so we wasted a bunch of time trying to get the rib lined up properly on the spar. When it just would not go, I removed ribs 9 through 13 from the spar, reworked the hole on 9, and put them all back on. The result looked like this:

Much measuring ensued to assure that the jig was perfectly aligned with the spar so that the wing would be true (no wash-out). With that done, it was time to precisely position the ribs. The wing skin comes in three pieces, two four-foot wide sections and a two-foot wide section. At each seam, there are a pair of doubled-up ribs so that there is plenty of surface area for bonding. These double ribs should be exactly aligned with the skin seams so we measured, measured, measured and carefully clamped and measured some more. It looked like this.

The single ribs are spaced 12″ apart but their position is not critical, since there is no seam in the skin, and they are completely invisible. Consequently, there is no need to clamp them in place.

With the ribs in position, it was time to mix ProSeal. Jim Bede, Jr. had assured me that ProSealing is straightforward but I was dubious, since I have read so many horror stories from RV-ers who struggled to seal their fuel tanks. Having been through the process, I now agree: it’s easy. The tricks seem to be a) measuring by weight (not volume) with an accurate, digital scale, and b) applying the ProSeal with a gun instead of popsicle sticks. I used a pneumatic gun but a squeeze gun would have worked, too.

After running a bead of ProSeal with the gun, it was a quick job to smooth it into a neat fillet with a popsicle stick.

With the ribs all bonded into place, the wings looked like this and we were done for the day.

That left time for conversation with Steve about where to pick up the construction when the kit is delivered to me in October. It seems that starting at the rudder pedals and then working through the control systems outward and rearward will do nicely. Once I reach the wings, for instance, I can construct and attach the flaps and ailerons. When I reach the tail, I can build and attach the horizontal stabilator trim tab and rudder. Fuselage skins go on last, since they, like the wing skins, are bonded in place.

I also got a chance to talk with Jim Bede, Sr. about the landing gear legs. These beasts are made from 3M S-Ply (f/k/a Scotch Ply). Regular fiberglass is about 50% glass and 50% resin. The S-Ply is about 78% glass and the fibers are unidirectional, with the exception of two thin sheets on the outsides of the legs. These outer layers have diagonal grain to add torsional strength to the legs.

Tomorrow: bonding the skins the fuel tanks and maybe some landing gear work.

I have lots more pictures in my N114AC Bede BD-4C Construction photo gallery.